Immunology Flashcards

Question

Generally how do leukocytes leave the blood vessel to reach the site of infection

Answer 1

Leukocytes adhere to endothelial cell adhesion molecules, which enables them to migrate out of the vascular system and attack pathogens, a process aided by pathogen generated chemotaxins and host chemokines whose expression the pathogen has induced.

Answer 2

complement system, coagulation system, fibrinolytic system and kinin system

Answer 3

Factor XII becomes activated upon contacting negatively charged substances such as collagen, producing Factor XIIa, which results in the production of thrombin, plasmin and bradykinin

Answer 4

Factor XII becomes activated upon contacting negatively charged substances such as collagen, producing Factor XIIa, which results in the production of thrombin, plasmin and bradykinin. Thrombin and plasmin hydrolyse the complement protein C3 to produce active C3a and C3b

Answer 5

C3a stimulates mast cells, C3b attaches to pathogens aiding their destruction by white blood cells and cleaves C5 into C5a and C5b

Answer 6

activates mast cells, is chemoattractant for white blood cells and also activates them

Answer 7

form a membrane attack complex that can attach to bacterial membranes and induce lysis (one subunit of C5b, C6, C7, C8 and 12-18 C9 subunits)

Answer 8

neutrophils

Answer 9

1) PRRs detect PAMPs causing release of TNFα and IL-1 inducing expression of adhesion molecules (e.g. selectins) on the endothelium 2) Neutrophils initially tether to and are captured by the endothelium via interaction between endothelial P-selectin and neutrophil expressed ligands, such as P-selectin glycoprotein 1 (PSGL1). involves interaction between neutrophil expressed integrins eg LFA1 and ICAM1 expressed by the endothelium. 3) Transmigration across the endothelium and basement membrane takes up to ∼15 minutes and requires both integrins and further adhesion molecules such as platelet/endothelial cell adhesion molecule 1 (PECAM1) 4) Numerous chemotaxins (e.g. C5a and the bacteria derived formyl-Met-Leu-Phe, fMLF) attract the neutrophils to the bacteria invader 5) Neutrophils eliminate pathogens via intracellular and extracellular mechanisms

Answer 10

Firm arrest and adhesion involves interaction between neutrophil expressed integrins such as lymphocyte-associated antigen 1 (LFA1) and intercellular adhesion molecule 1 (ICAM1) expressed by the endothelium.

Answer 11

transmigration can occur either paracellularly (between endothelial cells), or transcellularly (through endothelial cells, which takes longer ∼30 minutes).

Answer 12

phagocytosis and killing via reactive oxygen species and antibacterial proteins (e.g. cathepsin, lysozyme and defensins) degranulation to release antibacterial proteins into the extracellular fluid neutrophil extracellular traps (NETs), which are composed of a core DNA element alongside enzymes that immobilise pathogens, thus preventing spreading and facilitating phagocytosis, as well as likely also directly killing some pathogens

Answer 13

Neutrophil dysfunction is thought to be important in the development of sepsis in newborns and neonatal neutrophils fail to form NETs, which likely contributes to newborns being predisposed to infection

Answer 14

receptors for C3a, C5a and IgE, stimulation of these receptors results in release of histamine, heparin, leukotrienes, nerve growth factor and, unusually, pre-formed packets of cytokines.

Answer 15

chemical named for what is usually called histamine, a name resulting from it being an amine occurring in tissues (histos = tissue)

Answer 16

Histamine is formed from the amino acid histidine by histidine decarboxylase at the cellular level histamine is found in 4 cell types: mast cells, basophils, enterochromaffin-like cells (ECL) in the gut and histaminergic neurones in the brain. In mast cells and basophils, histamine is packaged in acidic granules with a high molecular weight heparin called macroheparin

Answer 17

C3a/C5a, SP, and IgE | trigger increased [Ca2+]i which leads to degranulation

Answer 18

C3a and C5a receptors are Gi-coupled; the βγ subunits activate PLCβ and induce intracellular Ca2+ release via IP3 this leads to degranulation and histamine release

Answer 19

SP primarily induces mast cell degranulation, not via neurokinin 1 receptors, but rather Mas-related gene X2 (MrgX2) receptors, which in human mast cells appear to be Gq-coupled resulting in PLCβ/IP3 mediated Ca2+ release

Answer 20

Allergen-induced cross linking of IgE with its high affinity receptor FcεRI induces phosphorylation of the adaptor protein linker for activation of T cells (LAT) that causes activation of PLCγ/IP3 mediated Ca2+ release.

Answer 21

``` true There are four histamine receptors that are GPCRs (H1-4) H1= Gq/11 H2= Gs H3=Gi H4=Gi ```

Answer 22

H1 = Gq/11 -> PLCβ -> IP3 + DAG/PKC (important in inflammation)

Answer 23

Gs coupled so increases AC, increasing cAMP/PKA important for gastric secretion

Answer 24

both decrease AC so decrease cAMP/PKA H3 is an important inhibitory autoreceptor in the CNS H4 is important for chemotaxis/cytokine release

Answer 25

- smooth muscle contraction (H1) in the ileum, bronchioles and uterus - blood vessel dilation, largely mediated via endothelial release of nitric oxide (H1) - itching evoked by activation of distinct sensory nerves (pruritoceptors, H1) - triple response of Lewis (H1) - increased heart rate (H2) - gastric acid secretion (H2) - brain neurotransmission (predominantly H1-3, but also H4)

Answer 26

2 possible enzymes: histaminase -oxidatively deaminates histamine to produce imidazole acetaldehyde, histamine N-methyltransferase -catalyses the transfer of a methyl group on to the nitrogen of the imidazole ring to produce NT-methylhistamine both products are inactive at histamine receptors.

Answer 27

histaminase (also called diamine oxidase) histamine N-methyltransferase (also called imidazole N-methyltransferase)

Answer 28

allergic rhinitis (hay fever) urticaria (incl. dermatographism urticaria) allergies such as nut allergy and penicillin allergy.

Answer 29

include swelling, itchiness, nasal congestion, watery eyes and in non-human animals poor coat quality

Answer 30

throat swells heart rate increases blood pressure drops rapid adrenaline treatment

Answer 31

a group of conditions where too many mast cells are present leading to excessive allergic-type reactions when an attack is triggered by various factors (heat, cold, stress, infection, exercise, drugs etc.)

Answer 32

Often results from a gain-of-function mutation in the receptor tyrosine kinase c-Kit/CD117 (D816V) causing enhanced mast cell proliferation and survival

Answer 33

Mastocytosis resulting from mast cell tumours has also been described in dogs and cats, but, non-cancerous mastocytosis has also been described in dogs, but, where tested, there was no c-Kit mutation

Answer 34

inhibition of mast cell degranulation

Answer 35

Sodium cromoglycate

Answer 36

inhibits mast cell degranulation MOA unclear but decreased Ca2+ influx is seen in mast cell activation in presence of sodium cromoglycate perhaps Sodium cromoglycate inhibits an inward Cl- channel required to maintain a negative enough membrane potential to enable sustained influxes of extracellular Ca2

Answer 37

mastocytosis | available as eye drops for the treatment of hay fever e.g. Opticrom and is occasionally used in the treatment of asthma

Answer 38

true thus β2-adrenoceptor agonists (salbutamol and formoterol) and phosphodiesterase (PDE) inhibitors (theophylline) used in the treatment of asthma are partially efficacious through mast cell inhibition although their main therapeutic action is via bronchodilation

Answer 39

omalizumab recognises IgE, decreases mast cell degranulation because allergen bound IgE induces mast cell degranulation when bound to its receptor FcεRI.

Answer 40

H1-receptor antagonists

Answer 41

salbutamol formoterol phosphodiesterase (PDE) inhibitors (theophylline) both types of drug work by increasing [cAMP] in mast cells to inhibit degranulation

Answer 42

mepyramine rapidly permeated the blood-brain barrier and caused drowsiness, and so were not suited for systemic use,

Answer 43

false not suited for systemic use, but it is still used in topical creams for treating insect bites. First generation drugs are also used in some cold/flu medications to aid sleeping

Answer 44

not cross the blood-brain barrier (terfenadine was the first)

Answer 45

Terfenadine was a blockbuster drug in the treatment of hay fever ($440 million in 1996, the year before withdrawal), but there were increasing reports of people taking it developing torsade de points syndrome (also known as prolonged QT interval) and also reports of sudden cardiac death

Answer 46

inhibits KV11.1/hERG, which is important for repolarisation of the action potential

Answer 47

Terfenadine is a prodrug, metabolised by the 3A4 isoform of cytochrome p450 (CYP450) to fexofenadine, which is the active compound

Answer 48

people with in conditions of diminished p450 3A4 activity (3A4 form of CYP450 metabolises terfenadine to fexofenadine, the active compound) p450 3A4 is inhibited by many drugs, as well as bergamottin, a component of grapefruit juice

Answer 49

non-drowsy and lack cardiac side-effects fexofenadine and loratadine

Answer 50

1: mepyramine 2: terfenadine 3: fexofenadine (also loratadine)

Answer 51

treating hay fever, allergy and urticaria

Answer 52

antihistamines are of little use in treating hypersensitivity reactions in cattle

Answer 53

administered i.m. to counteract systemic vasodilatation and reduction in tissue perfusion. also reduces bronchospasm no: noradrenaline is such a potent vasoconstrictor it causes reflex bradycardia and is thus unsuitable corticosteroid hydrocortisone is often co-administered for its anti-inflammatory effects

Answer 54

imatinib only efficacious in patients not presenting with the common D816V c-Kit mutation.

Answer 55

A combination of H1R and H2R antagonists

Answer 56

a relatively common allergic condition in dogs (~10%) although H1-receptor antagonists can be used they are often inefficacious. Oclacitinib is a beneficial treatment, which works by inhibiting Janus kinases (JAK, greatest specificity for JAK1) A canine monoclonal antibody against IL-31 has also been developed

Answer 57

inhibits JAK JAKs are common to many cytokine signalling pathways associated with allergic skin diseases and thus oclactinib lowers pro-inflammatory signalling and can be used as an alternative to corticosteroids and ciclosporin

Answer 58

parietal cells

Answer 59

are responsible for secreting HCl into the stomach to aid digestion and kill pathogens

Answer 60

in the gastric mucosa secrete HCO3- ions which are trapped in mucous creating a protective barrier (pH6-7)

Answer 61

can contribute to the pathogenesis and pain associated with peptic ulcers and gastro-oesophageal reflux disease.

Answer 62

secrete gastrin on to ECL cells where it binds to CCK2 receptors to produce an increase in ECL [Ca2+], which causes ECL cells to release histamine.

Answer 63

acts at Gs-coupled H2-receptors on parietal cells causing an increasing in cAMP and PKA activity. PKA phosphorylates proteins involved in trafficking of K+/H+ pumps to the apical membrane resulting in enhanced K+/H+ pump activity and thus increased H+ release

Answer 64

it is a negative regulator of H+ release and has both direct and indirect mechanisms of inhibition

Answer 65

activation of Gi-coupled SST2R on parietal cells counteracts the effects of histamine (direct inhibition), activation of SST2R on G and ECL cells reduces gastrin and histamine release respectively (indirect inhibition).

Answer 66

CCK2 receptor antagonist (eg proglumide)

Answer 67

CCK2 receptor antagonist (decreases histamine secretion) however its use in treating peptic ulcers has been surpassed

Answer 68

H2-antagonists cimetidine (Tagamet)

Answer 69

inhibit CYP450 soon had competition from ranitidine

Answer 70

omeprazole

Answer 71

converted to their active form in the acidic environment of the parietal cell and form disulphide bonds with the K+/H+ pump. However, PPIs are broken down by H+, have a slow onset to maximal effectiveness and predominantly metabolised by CYP2C19

Answer 72

CYP2C19 exhibits significant genetic polymorphism producing extensive and poor metabolisers, especially in Asians (1-2% in Europeans vs. ~20% in Asians).

Answer 73

vonoprazan a potassium-competitive acid blocker (P-CAB)

Answer 74

has greater stability than PPIs in H+ and CYP2C19 is less vital in its metabolism

Answer 75

``` PPIs/ P-CABs CCK2 inhibitors H2 antagonists antacids cholinergic blockade vagotomy eradication of Helicobacter pylori stopping NSAID use ```

Answer 76

Gaviscon help neutralise pH in stomach

Answer 77

true acetylcholine stimulation of muscarinic type 3 receptors (M3R) on parietal cells enhances acid release, which is then inhibited by atropine/vagotomy both virtually obsolete

Answer 78

clarithromycin

Answer 79

Helicobacter are not generally thought to be the cause although they are often present, e.g. H. heilmannii

Answer 80

NSAIDs inhibit prostaglandin (PG) synthesis and PGE2 acts on ECL cell EP2/3R to inhibit gastric acid secretion, as well as enhancing mucin (EP4R) and bicarbonate secretion (EP1/2R).

Answer 81

In patients at risk of developing peptic ulcers (e.g. the elderly) or those with gastric complications misoprostol - a synthetic prostaglandin E 1 (PGE1) analogue

Answer 82

a combination of the NSAID diclofenac and misoprostol that can be used in the chronic treatment of rheumatoid arthritis with misoprostol acting as a prophylactic against NSAID-induced ulceration

Answer 83

misoprostol

Answer 84

originally identified as a slow (brady) contractor (kinin) of guinea pig ileum smooth muscle (slow being relative to tachykinins like SP)

Answer 85

by the action of kallikrein upon kininogens, which exist as high- and low-molecular weight forms

Answer 86

Hageman factor/Factor XII to become activated by contacting negatively charged surfaces, such as lipopolysaccharide, collagen or basement membrane. Activated Hageman factor is a protease that converts plasma prekallikrein to kallikrein, which clips HMW-kininogen to bradykinin and LMW-kininogen in tissues to kallidin

Answer 87

by contacting a -ve surface Hageman factor only contacts negatively charged surfaces, such as lipopolysaccharide, collagen or basement membrane when leaking out of leaky blood vessels during inflammation

Answer 88

clipped kininase II

Answer 89

via several peptidases, including serum carboxypeptidase, results in the removal of the C-terminal arginine to form des-Arg-bradykinin, which is an agonist for bradykinin B1 receptors

Answer 90

a peptidyl dipeptidase that inactivates kinins by removing the two C-terminal amino acids, this enzyme is angiotensin converting enzyme (ACE)

Answer 91

bradykinin B1 and B2 receptors and are both Gq-coupled GPCRs

Answer 92

B1 receptors are upregulated during inflammation through the action of cytokines, such as IL-1, and respond primarily to des-Arg-bradykinin (bradykinin itself is a very poor B1 agonist), B2 receptors are constitutively expressed and potently activated by bradykinin and kallidin (des-Arg-bradykinin has virtually no efficacy)

Answer 93

causes an increase in [Ca2+], which activates cytosolic phospholipase A2 (cPLA2) resulting in prostacyclin (PGI2) production and endothelial nitric oxide synthase (eNOS) resulting in NO production PGI2 and NO diffuse to the vascular smooth muscle cell layer and through increasing cAMP and cGMP levels respectively, mediate vasodilatation

Answer 94

no - not only reduce angiotensin II levels, thus reducing vasoconstriction, but they also cause an increase in bradykinin levels and thus enhance vasodilatation

Answer 95

Activation of bradykinin receptors causes activation of nociceptors and drives pain (due to increased [Ca2+]i). Bradykinin also induces nociceptor sensitisation because activation of Gq GPCRs results in activation of PKC, which phosphorylates numerous ion channels involved in the sensation of pain.

Answer 96

C1-esterase inhibitor (C1-INH).

Answer 97

hereditary angioedema HAE, prevalence ~0.01%

Answer 98

mutation in the gene encoding C1-INH causes excessive levels of bradykinin resulting in sufferers experiencing periods of severe and painful swelling

Answer 99

Type I HAE results from mutations that compromise C1-INH synthesis/secretion, whereas Type II HAE results from mutations that produce inactive C1-INH

Answer 100

0.1% but is higher (~0.5%) in African American it is currently poorly understood what makes people susceptible to this, but there are indications that it may be linked to genetic variation in genes that regulate the immune system

Answer 101

recombinant C1-INH, kallikrein inhibitors and the B2 antagonist icatibant can be used anecdotal evidence for efficacy in treating ACE inhibitor associated angioedema.

Answer 102

icatibant (B2 antagonist)

Answer 103

Plenty of research to develop B1 antagonists for inflammatory pain, but none clinically available

Answer 104

a very broad group of proteins that are largely, but not exclusively, synthesised and released by cells of the immune system and generally help to coordinate the immune response

Answer 105

they contain granules containing pre-formed cytokines. Thus, because most cells have to synthesise cytokines, drugs that inhibit cytokine transcription (e.g. corticosteroids, see later) have a major impact on immune responses

Answer 106

over 100 cytokines, some of which are pro-inflammatory and some of which are anti-inflammatory.

Answer 107

interleukins chemokines interferons colony stimulating factors

Answer 108

are IL-1 (actually three cytokines: the agonists IL-1α and IL-1β and an endogenous receptor antagonist, IL-1ra) and TNFα predominantly released from macrophages

Answer 109

promote proliferation and maturation of other immune cells, as well as causing fever (IL-1).

Answer 110

yes | which inhibit cytokine production and inhibit some T-cell responses (e.g. IL-10 and IL-1ra).

Answer 111

originally observed to communicate between leukocytes

Answer 112

non-cytokines also act as chemoattractants and chemokines have other roles, e.g. CCL3 induces mast cell degranulation by acting at CCR1 receptors.

Answer 113

the cysteine residues in the N-terminus of the peptide chain, CXC chemokines have a single amino acid separating the two cysteines, CC chemokines have two adjacent chemokines, C chemokines only have one N-terminus cysteine and lastly, CX3C chemokines have three amino acids separating the two cysteines these classes are also sometimes termed α, β, γ and δ.

Answer 114

(IFN) α, β and γ, the former two have anti-viral activity and the latter has a role in induction of Th1 responses

Answer 115

stimulate the formation of maturing colonies of leukocytes and are primarily used to overcome deficits in a person’s white-blood cell count, e.g. following chemotherapy

Answer 116

Nerve growth factor released from both macrophages and mast cells and is a potent sensitising agent, i.e. it does not excite nociceptors directly, but rather activates signalling pathways that result in a lesser stimulus causing pain

Answer 117

following NGF injection, there is a >5°C lowering of the temperature required to generate pain in humans

Answer 118

mediated by the high affinity NGF receptor tropomyosin-related kinase A (TrkA).

Answer 119

in the treatment of inflammatory pain, blocking the actions of NGF is desirable and anti-NGF monoclonal antibodies such as tanezumab have been developed, but are still in clinical trials

Answer 120

tanezumab inflammatory pain

Answer 121

a protein produced by many cells, which downregulates both inflammatory cell activation and mediator release, actions that are brought about by binding to the GPCR formylpeptide receptor 2 (FPR2)

Answer 122

leukotrienes, platelet-activating factor prostanoids arachidonic acid (exception = PAF)

Answer 123

on demand from membrane phospholipids by the action of phospholipases.

Answer 124

Platelet activating factor

Answer 125

a 20-carbon unsaturated fatty acid containing four double bonds AKA 5,8,11,14-eicosatetraenoic acid eicosa refers to the 20 carbon atoms and tetraenoic to the 4 double bonds and thus lipid mediators are often referred to as eicosanoids

Answer 126

liberation of arachidonic acid from membrane phospholipids and the usual one-step process involves PLA2.

Answer 127

cPLA2 which is activated by a combination of phosphorylation and Ca2+

Answer 128

can be stimulated by a plethora of substances, e.g. bradykinin acting at B2 receptors raises [Ca2+]i TNFα acts at TNFR1 to promote MAPK phosphorylation of cPLA2 at serine 505 and serine 727, as well raising [Ca2+]i via TNFR2.

Answer 129

production of arachidonic acid (prostanoid and leukotriene precursor) and lysoglyceryl-phosphorylcholine (PAF precursor called lyso-PAF)

Answer 130

synthesised by lipoxygenase enzymes from arachidonic acid

Answer 131

cytosolic enzymes, expressed primarily in the lungs and leukocytes

Answer 132

Arachidonic acid is converted by 12-lipoxygenase to produce 12-HETE (hydroxyeicosatetraenoic acid), which is a chemotaxin and 5-lipoxygenase to produce leukotriene A4 (LTA4).

Answer 133

converted in cells expressing the cytosolic enzyme LTA4 hydrolase to LTB4, whereas in cells expressing the membrane bound LTC4 synthase (also called glutathione S-transferase) LTA4 is converted into LTC4, which in turn is cleaved by peptidases to produce LTD4 and LTE4.

Answer 134

the cysteinyl leukotrienes (CysLT)

Answer 135

LTB4 acts at BLT1 and BLT2 receptors, the CysLTs act at CysLT1 and CysLT2 receptors; BLT receptors can be either Gq- or Gi-coupled, whereas CysLT receptors are Gq-coupled. all act on GPCRs

Answer 136

CysLT1: LTD4 >> LTC4 > LTE4 CysLT2: LTC4 = LTD4 > LTE4.

Answer 137

potent chemoattractant and activator of neutrophils and macrophages, it upregulates neutrophil adhesion molecule expression promotes macrophage cytokine release

Answer 138

LTB4 makes LTA4 hydrolase a therapeutic target

Answer 139

caused dermatitis

Answer 140

cause bronchoconstriction, increase vascular permeability mucous secretion

Answer 141

from both mast cells and eosinophils characteristic leukocytes in airways of asthmatics and all CysLTs cause bronchoconstriction

Answer 142

montelukast (CysLT1 receptor antagonist) is used in maintenance treatment of asthma

Answer 143

either 12-lipoxygenase conversion of LTA4 to LXA4 or 15-lipoxygenase conversion of arachidonic acid to 15S-HETE, which is then converted by 5-lipoxgenase to LXA4

Answer 144

binds to the FPR2, Gi-coupled reduces neutrophil chemotaxis and degranulation, as well as acting as an antagonist of CysLT1 receptors

Answer 145

through the action of acetyltransferase on lyso-PAF

Answer 146

it has effects upon a variety of cell types and acts through GPCRs that are variously coupled

Answer 147

increases thromboxane (TXA2) production in platelets can be spasmogenic; chemotactic for neutrophils activates PLA2

Answer 148

experiments in the 1930s showed that semen contained a lipid that could evoke uterine smooth muscle, named prostaglandin (PG) because of originating from the prostate gland

Answer 149

Arachidonic acid is metabolised to prostaglandins by cyclooxygenases (COX) Following the production of PGH2, it is the cell specific enzymes that are responsible for the downstream production of a particular PG or thromboxane

Answer 150

COX catalyses two reactions: arachidonic acid is first cyclised and oxygenated forming the endoperoxide PGG2; the hydroperoxyl in PGG2 is then reduced to form PGH2.

Answer 151

COX-1 is constitutively expressed in many cell types, whereas COX-2 expression is induced in inflammation, although some constitutive expression does occur.

Answer 152

PGs and TX

Answer 153

the number of carbon-carbon double bonds in the final structure

Answer 154

if eicosatrienoic acid (three C=C double bonds) is used in place of eicosatetraenoic acid as a substrate then the resulting PGs have one fewer double bond and are named, for example, PGE1, and if eicosapentaenoic acid (five C=C double bonds) is used as a substrate then PGs have one more double bond and are named, for example, PGE3

Answer 155

varies , PGE2 and PGI2 tend to be produced locally by tissues and blood vessels, PGD2 is predominantly released by mast cells and in chronic inflammation macrophages release PGE2 and TXA2

Answer 156

false | Prostanoids act at GPCRs and some PGs can activate multiple receptors, e.g. PGD2 can activate TP and DP receptors

Answer 157

- DP1, EP2, EP4 and IP receptors are Gs-coupled causing increased cAMP production - EP1, FP and TP receptors are Gq-coupled causing an increase in [Ca2+]i - DP2 and EP3 receptors are Gi-coupled causing decreased cAMP production

Answer 158

- PGD2 = vasodilatation, inhibition of platelet aggregation and relaxation of GI (GI)/uterine muscle via DP1 receptors; bronchoconstriction via TP receptors - PGE2 = bronchial/GI smooth muscle contraction (EP1), bronchodilation, vasodilatation and relaxation of GI smooth muscle (EP2), contraction of GI/uterine smooth muscle and fever (EP3), and sensitisation of nociceptors (EP4) - PGI2 = vasodilatation and inhibition of platelet aggregation - TXA2 = vasoconstriction, bronchoconstriction and platelet aggregation - PGF2α = uterine contraction in humans, bronchoconstriction in cats/dogs

Answer 159

balance between the pro-aggregation effects of TXA2 (produced by platelets) and the anti-aggregation effects of PGI2 (produced by endothelial cells) the balance shifts towards TXA2, platelets aggregate and the damage is sealed.

Answer 160

atherosclerotic plaque rupture damages the endothelium and the platelets adhere forming a clot; part of the clot can break off and block a cerebral artery

Answer 161

fish oil is high in eicosapentaenoic acids resulting in the production of PGI3 and TXA3, TXA2 is far more potent than TXA3, but PGI3 is more potent than PGI2 thus there is an overall tip in the balance towards anti-aggregation and less vasoconstriction

Answer 162

inhibit COX by entering a hydrophobic channel on the enzyme and forming hydrogen bonds with an Arg120, this prevents the entrance of fatty acids, like arachidonic acid, into the catalytic domain and thus PG production is stopped. This inhibition is reversible

Answer 163

COX-1 is constitutive and expressed in many tissues, whereas COX-2 is induced during inflammation. It was thus hypothesised that drugs that only inhibited COX-2 would result in all of the benefits of COX inhibition (analgesia, decreased swelling and antipyresis etc.) without any of the side effects such as gastric bleeding

Answer 164

NSAIDs have to enter the hydrophobic tunnel of COX to reach Arg120 and whereas COX-1 has a narrow tunnel, COX-2 has a wider tunnel. Consequently, drugs have been developed that have bulky sulphur-containing side groups and selectively act upon COX-2, but not COX-1 because they cannot enter the narrow, hydrophobic tunnel

Answer 165

yes Most NSAIDs, such as ibuprofen, are non-selective because they are small and enter the hydrophobic tunnels of both COX-1 and COX-2

Answer 166

generally name ends in -coxib | eg etoricoxib

Answer 167

non-selective: ibuprofen | COX2 selective: etoricoxib

Answer 168

GI bleeding no - accounts for approximately 5000 deaths in the UK each year

Answer 169

adults aged 65+, people with a history of gastric ulceration and those taking NSAIDs chronically yes but must be co-administered with PPIs or with the PGE1 analogue misoprostol.

Answer 170

although COX-2 is upregulated in inflammation, it is also constitutively expressed in some endothelial and vascular smooth muscle cells (e.g. in the kidney) and thus its inhibition results in decreased PGI2 production – PGI2 is vasodilatory and decreases platelet aggregation also inhibiting COX-2 raises levels of endogenous inhibitors of eNOS, which would lead to decreased NO production. Consequently, some, but not all, COX-2 inhibitors have been associated with increased myocardial risk

Answer 171

it was associated with increased myocardial risk (rofecoxib is a selective COX2 inhibitor)

Answer 172

Current guidance suggests that COX-2 inhibitors should be reserved for people suffering from chronic inflammation, e.g. osteoarthritis/rheumatoid arthritis, who are not thought to have a substantial cardiovascular risk and when conventional NSAIDs are thought to pose a high GI risk NB GI problems can still occur with COX-2 inhibitors

Answer 173

perhaps because they interfere with the healing of pre-existing ulcers

Answer 174

false although it was thought that the non-selective NSAID naproxen carried a lower risk, results from a recent large trial comparing naproxen, ibuprofen and a COX-2 inhibitor did not support this hypothesis (the COX-2 inhibitor did however show significantly lowered GI side effects)

Answer 175

Rather than forming a hydrogen bond with Arg120, it acetylates Ser530 and irreversibly inactivates COX, an action that explains aspirin’s long-lasting actions

Answer 176

acetylsalicylate

Answer 177

by donating an acetyl group to COX, salicylate is formed

Answer 178

reversibly inhibit COX (like most NSAIDs) but the concentrations produced are unlikely to have a significant therapeutic effect

Answer 179

platelets express COX-1 and TX synthase and are a major source of TXA2 (induces platelet aggregation and vasoconstriction), whereas endothelial cells predominantly produce PGI2 (inhibits platelet aggregation and vasodilatation); acetylated COX-1 can be replaced by newly synthesised protein in endothelial cells, but TXA2 production by platelets is switched off for their lifetime (~10 days). Therefore, overall switch to beneficial, anti-thrombotic effects, with a lower risk of stomach ulcers (but PPIs are often co-prescribed to limit the risk.)

Answer 180

Although weakly COX-1 selective, aspirin also acetylates COX-2

Answer 181

COX-2 no longer producing intermediates for PG and TXA2 synthesis, but instead 15R-HETE, which is the stereoisomer of 15S-HETE (product of 15-LO conversion of arachidonic acid, which is used to synthesise LXA4 5-LO then converts 15R-HETE to aspirin-triggered lipoxin – ATL, also known as 15R-epi-lipoxin A4, which has similar functions to LXA4.

Answer 182

aspirin triggered lipoxin has similar functions to LXA2 so its production contributes to the anti-inflammatory action of aspirin

Answer 183

GI bleeding (PGs inhibit gastric acid secretion and increase the release of protective mucin), renal insufficiency and nephropathy (PGE2/PGI2 involved in maintenance of renal blood flow), stroke/myocardial infarction (constitutive expression of COX-2 in endothelial/vascular smooth muscle cells, inhibition of which results in decreased PGI2 production, PGI2 is vasodilatory and decreases platelet aggregation), bronchospasm (COX inhibition implicated, mechanism unclear).

Answer 184

Reye's Syndrome Salicylism

Answer 185

occurs almost exclusively in children (hence not recommended for use in children under the age of 16) characterised by hepatic encephalopathy, often occurs when aspirin is taken for treating viral symptoms

Answer 186

yes health warnings in the late 1980s have reduced the cases from 41/year in the 1980s to only 1 case of Reye's Syndrome in 2002 and 3 further suspected cases up to 2009

Answer 187

– essentially the result of an overdose of aspirin, often seen in children or in suicide attempts

Answer 188

a progressive condition resulting from Kreb’s cycle inhibition and uncoupling of oxidative phosphorylation, primarily in skeletal muscle, which causes increased O2 consumption and thus increased CO2 production. CO2 stimulates peripheral and central chemoreceptors resulting in increased ventilatory rate causing respiratory alkalosis, which can be compensated for by increased renal bicarbonate excretion. However, larger doses depress the respiratory centres and CO2 accumulates, which is superimposed upon the reduced plasma bicarbonate to cause respiratory acidosis, which can combine with metabolic acidosis resulting from accumulated acidic metabolites due to disrupted carbohydrate metabolism. Fever and repeated vomiting occur, followed by dehydration, respiratory depression, coma and death

Answer 189

fluids are administered, as is bicarbonate to enhance aspirin elimination, activated charcoal adsorbs aspirin in the GI tract in severe cases haemodialysis may be required.

Answer 190

known as acetaminophen in the Canada, U.S., Iran and Japan

Answer 191

Both names are derived from a chemical name of the drug: N-acetyl-para-aminophenol and N-acetyl-para-aminophenol respectively

Answer 192

it is a v poor anti-inflammatory (but does have good anti-pyretic and analgesic effects)

Answer 193

COX1 and 2 (but not through binding to arginine 120 or acetylation)

Answer 194

through reduction of the active site in COX enzymes required for the production of PGH2 from PGG2

Answer 195

paracetamol inhibits the COX-1 splice variant COX-3 with greatest potency, and COX-3 might be preferentially expressed in the brain, however, COX-3 is likely non-functional in humans due to a shift in the reading frame producing a truncated COX protein.

Answer 196

some paracetamol metabolites have also been demonstrated to have actions that contribute to analgesia

Answer 197

coagulation using hepatic enzymes when these are saturated, oxidases act to metabolise paracetamol to NAPQI, which is usually conjugated to glutathione

Answer 198

there is insufficient glutathione to eliminate paracetamol and NAPQI can oxidise the thiol groups of cellular proteins resulting in major hepato- and renal toxicity

Answer 199

when paracetamol dosage is high enough to saturate hepatic coagulation enzymes needed to eliminate the drug, oxidases (CYP2E1) metabolise paracetamol to NAPQI NAPQI is also formed at therapeutic doses suggesting that other pathways for its formation exist

Answer 200

. Symptoms often do not occur until 24-48 hours post-ingestion and begin with nausea and vomiting and lead to liver failure induced death

Answer 201

If the patient is seen soon after ingestion then prevention of liver damage can be attempted by administering substances that increase hepatic glutathione production, e.g. acetylcysteine

Answer 202

acetylcysteine | increases hepatic glutathione production

Answer 203

Toxicity occurs from as little as 150 mg/kg, for a 65 kg adult = 9.75 g, paracetamol often comes in packs of 16 x 500 mg = 8 g, e.g. not difficult to buy enough to overdose. However, pre-1998, pack sizes were often 100 x 500 mg, legislation in England and Wales restricted over the counter packs in non-pharmacy premises to 16 x 500 mg, studies show that this caused a significant reduction in paracetamol-related deaths

Answer 204

Alcohol can increase risk of toxicity because it upregulates CYP2E1, which converts paracetamol to NAPQI, fasting is also a risk, perhaps because of decreased hepatic glutathione levels.

Answer 205

aspirin is not suitable for use in cats because they lack the ability to conjugate salicylate with glycine. Paracetamol should also be avoided in dogs and especially in cats because they lack enzymes that in humans enable efficient excretion

Answer 206

Phenylbutazone NSAID used for treating horses but causes a plethora of side effects in humans (it is also abused in racehorses, which are regularly tested for bute use).

Answer 207

an NSAID licensed for use in cats and dogs

Answer 208

NSAID used for dogs and horses

Answer 209

because it was detected in serum following clotting of the blood and caused vasoconstriction

Answer 210

after coagulation because platelets contain 5-HT, which is released during platelet activation and aggregation and induces further platelet aggregation, as well as causing vasoconstriction in damaged blood vessels

Answer 211

true but can also dilate | 5-HT can cause both vasodilatation and vasoconstriction depending upon receptor expression

Answer 212

intestinal enterochromaffin cells and in serotonergic neurones of the enteric (and central) nervous system.

Answer 213

from tryptophan through the actions of tryptophan hydroxylase (Tph) and L-aromatic acid decarboxylase (= dopa decarboxylase)

Answer 214

from tryptophan in both serotonergic neurones and enterochromaffin cells.

Answer 215

Tph conversion of tryptophan to 5-hydroxytryptophan

Answer 216

Tph1 is primarily expressed in enterochromaffin cells and Tph2 is predominantly expressed in neurones

Answer 217

false | platelets expresses SERT which take up 5-HT from intestinal circulation

Answer 218

Platelets express a serotonin transporter (SERT) enabling platelets to become loaded with 5-HT when they pass through the intestinal circulation (platelets are not thought to synthesis their own 5-HT), which has a high 5-HT concentration

Answer 219

2 steps: 1) oxidative deamination via monoamine oxidase 2) through oxidation to produce 5-hydroxyindoleacetic acid (5-HIAA) 5-HIAA is excreted in the urine and levels of urine 5-HIAA are a measure of systemic 5-HT synthesis.

Answer 220

- 5-HT1A, B, D – F are Gi-coupled GPCRs (note that there is no 5-HT1C) - 5-HT2A – C are Gq-coupled GPCRs - 5-HT3 is an ionotropic receptor/ligand gated ion channel - 5-HT4 is a Gs-coupled GPCR - 5-HT5A is a Gi-coupled GPCR - 5-HT6 is a Gs-coupled GPCR - 5-HT7 is a Gs-coupled GPCR (2A – C are Gq-coupled GPCRs; 3 is ionotropic; 1 and 5A are Gi GPCR; all the rest are Gs GPCR)

Answer 221

chemicals in the intestine or blood or disturbance of the labyrinth in the ear

Answer 222

the vomiting centre and the chemoreceptor trigger zone (CTZ), both of which are located in the medulla

Answer 223

circulating chemicals can activate the CTZ, which sends signals to the vomiting centre to produce emesis

Answer 224

Both visceral afferents that project to the CTZ and the CTZ itself express 5-HT3 receptors inhibition of these receptors, eg by ondansetron is an effective preventative and treatment of vomiting

Answer 225

chemotherapy-induced nausea and vomiting (CINV), which commonly results from anti-cancer drugs its main site of action appears to be the 5-HT3 receptors in the CTZ

Answer 226

treat nausea and vomiting of most causes e.g. post-surgery, where anaesthetic drugs can lead to emesis.

Answer 227

H1 receptor antagonists (effective against motion sickness and other causes of emesis) non-selective muscarinic receptor antagonists (anti-vomiting/nausea effects via M1 receptors) Dopamine D2 receptor antagonists (act on CTZ)

Answer 228

can cause acute dystonia (due to effects upon dopaminergic signalling in the brain)

Answer 229

Domperidone was designed to be more peripherally selective and is observed to produce acute dystonia less frequently (both are Dopamine D2 receptor antagonists )

Answer 230

no | they appear to lack the brainstem component of vomiting and cannot vomit

Answer 231

no Rodents appear to lack the brainstem component of vomiting and cannot vomit in fact the hypoglycaemia that can result is highly dangerous

Answer 232

horses and rodents

Answer 233

because of a muscle that acts as a one-way valve to allow food down, but not up, the oesophagus – humans have this muscle too, but it is not as strong and thus we can, and do, vomit

Answer 234

a severe headache that occurs in about 1 in 5 women and 1 in 15 men, usually beginning in young adulthood.

Answer 235

with or without aura

Answer 236

a progressive visual disturbance, which occurs in approximately 20% of migraineurs and is followed about 30 minutes later, by the migraine itself

Answer 237

throbbing headache, often starting unilaterally and accompanied by nausea and vomiting, photophobia and prostration; the length of the attack is usually several hours and people may often feel “hungover” following an attack, some suggest that hangovers are a form of migraine

Answer 238

likely derived from the Greek hemikrania, meaning pain on one side of the head

Answer 239

Although migraine can be triggered in some sufferers by specific stimuli (e.g. particular food such as red wine or chocolate), the underlying causes are poorly understood

Answer 240

vascular hypothesis brain hypothesis inflammation hypothesis (The brain and inflammation hypotheses are not necessarily mutually exclusive)

Answer 241

intracerebral vasoconstriction produces an aura and a subsequent extracerebral vasodilatation causes headache

Answer 242

modern measurements have shown that although changes in cerebral blood flow occur during migraine, headache begins during vasoconstriction and not all stimuli that cause similar cerebral blood flow changes produce headache.

Answer 243

– a wave of cortical spreading depression (CSD) spreads across the brain and is associated with the aura component of migraine. CSD is a slowly propagating 2-5mm/min wave of near-complete depolarisation, which results in silencing of neuronal electrical activity for several minutes (hence depression). CSD can be triggered by elevated extracellular [K+], such as that occurring following hyperactive neuronal firing and alongside neuronal depolarisation, ionic imbalance occurs and numerous mediators including H+, glutamate, NO, arachidonic acid, and 5-HT are released. CSD implies an important role for ion channels in migraine, and many preventative drugs work on ion channels.

Answer 244

activation of trigeminal nociceptors that innervate the meninges and extracranial blood vessels (remember, the brain itself is not innervated by nociceptors = no pain) is the initial event in migraine resulting in pain and neurogenic inflammation through CGRP release.

Answer 245

some evidence eg a Cocker Spaniel that would display signs of fearfulness and be very quiet for 1-2 hours before onset of vocalisation, low head carriage, refusal to eat and drink and occasional vomiting. Attacks occurred 1-2 times/month, persisted for up to 3-days and were followed by 1-2 days of quietness before a return to normal behaviour.

Answer 246

Topiramate | opioids and NSAIDs were inefficacious

Answer 247

as CSD occurs there is silencing of the electroencephalograph (EEG), coupled with an increase in [K+] and neuronal depolarisation (shown by a decreased direct-current, DC)

Answer 248

NO, 5-HT and AA can cause activation and sensitisation of nociceptors innervating blood vessels and may even reach meningeal nociceptors due to the disruption of the BBB as a result of upregulation of matrix metalloprotease (MMP)

Answer 249

During migraine, as CSD occurs there is silencing of the EEG, coupled with an increase in [K+] and neuronal depolarisation Also, mediators released, eg NO, 5-HT and AA can cause activation and sensitisation of nociceptors innervating blood vessels and may even reach meningeal nociceptors due to the disruption of the BBB as a result of upregulation of MMP activity Activation of nociceptors results in the release of CGRP, SP and neurokinin A, which further drive inflammatory pain and is enhanced by the activation of a parasympathetic reflex involving activation of the SSN and the sphenopalatine ganglion (SPG) leading to release of VIP, NO, and ACh.

Answer 250

nausea and vomiting is a common feature of migraine

Answer 251

During migraine: the urine levels of 5-HIAA rise and blood levels of 5-HT drop, many successful anti-migraine drugs target 5-HT function

Answer 252

a 5-HT1B/D/F agonist used to treat an acute migraine attack, action at 5-HT1B causes vasoconstriction and 5-HT1D/F agonism inhibits nociceptor activity

Answer 253

vasoconstriction in peripheral vascular beds is an unwanted side-effect and is contraindicated in coronary disease

Answer 254

poorly absorbed when taken orally, does not cross the BBB to any great extent and has short duration of action (t1/2 = 1.5 hours)

Answer 255

orally nasal spray subcut injection

Answer 256

development of selective 5-HT1D agonists has proved therapeutically disappointing, which suggests that 5-HT1F agonists may be fruitful

Answer 257

naratriptan naratriptan has a longer duration of action, can cross BBB and has fewer cardiac side effects

Answer 258

Lasmiditan, a non-triptan 5-HT1F agonist

Answer 259

lasmiditan is 440 times more potent for 5-HT1F receptors compared to 5-HT1B/D receptors and thus does not cause vasoconstriction, it is also far more lipophilic readily crosses the BBB where it inhibits nociceptor activity and CGRP release

Answer 260

can be used to help control acute symptoms

Answer 261

treatment ladder: starts with an NSAID (e.g. ibuprofen), sometimes with an antiemetic, such as domperidone, before moving on to triptans. Use of painkillers should be limited to no more than 2-3 days a week or 10 days a month to prevent overuse and to allow preventative agents the opportunity to work.

Answer 262

to find a drug that suits the individual patient and effective drugs should generally be continued for at least 4-6 months before a trial of discontinuation

Answer 263

``` propranolol amitriptyline topiramate botulinum toxin A erenumab ```

Answer 264

β-adrenoceptor antagonists are thought to work by preventing the extracerebral vasodilation, or by acting on the central catecholaminergic system asthmatics

Answer 265

an antidepressant used, at lower doses, as a migraine preventative

Answer 266

unclear, but is thought to involve inhibition of Nav channels and inhibition of noradrenaline and serotonin uptake

Answer 267

can also be sedative and typically causes a dry mouth due to anticholinergic action

Answer 268

an anti-epileptic repurposed as a migraine preventative acts on numerous ion channels including voltage-gated sodium channels (inhibition) and GABA-A receptors (facilitation)

Answer 269

tingling hands and feet

Answer 270

only advisable in patients suffering from chronic migraine (defined as headaches on 15 or more days/month) and in whom standard preventative agents have failed.

Answer 271

by intramuscular injection to the head and neck

Answer 272

thought unrelated to its muscular relaxant action, but may involve decreased release of neurotransmitters from nociceptors.

Answer 273

during an attack CGRP levels in the external jugular vein are elevated CGRP infusion induces headaches and migraine-like attacks in migraineurs, but not in non-migraineurs.

Answer 274

the former sequestering CGRP, the latter functioning as receptor antagonists small molecule CGRP receptor antagonists

Answer 275

erenumab for preventative treatment of migraine in adults and prophylaxis of migraines in adults who experience at least 4 migraines/month respectively.

Answer 276

Familial hemiplegic migraine, involving migraine and half body paralysis (rare)

Answer 277

true it is common to for migraine with aura to cause one sided sensory symptoms

Answer 278

inherited through mutations in different genes, one of which, CACNA1C, encodes the voltage-gated Ca2+ channel 1.2 α subunit (CaV1.2).

Answer 279

Mutations produce variable effects in channel function and may lead to a lower threshold for CSD initiation.

Answer 280

Although randomised trials have not been conducted, there is some evidence that the CaV inhibitors are efficacious in both aborting attacks and as prophylactics.

Answer 281

CACNA1C - encodes the voltage-gated Ca2+ channel 1.2 α subunit (CaV1.2) and is mutated in FHM TRESK

Answer 282

a 2-pore domain K+ channel plays a role in regulating the resting membrane potential and some dominant negative mutations in TRESK are associated with migraine

Answer 283

regulates resting potential and is expressed by nociceptors and loss of TRESK activity may predispose to migraine attacks

Answer 284

TRESK agonists a potential therapeutic target in the treatment/prevention of migraine.

Answer 285

the induction phase and the effector phase

Answer 286

by an antigen being presented to a naïve CD4+ or CD8+ T cell by an APC (macrophage or dendritic cell), which has ingested a pathogen, breaks it down by proteolysis and then presents peptide fragments

Answer 287

synthesise and express IL-2 receptors and release IL-2, which acts in autocrine fashion (i.e. on itself) causing generation and proliferation of T-helper zero (Th0) cells. Autocrine action of IL-4 causes the production of Th2 cells, which in turn activate B cells to proliferate and give rise to plasma cells that secrete antibodies and memory B cells

Answer 288

activation of complement, labelling of bacteria for phagocytosis, linkage with natural killer cells to kill antibody coated cells activation of mast cells/basophils

Answer 289

B cell proliferation and differentiation.

Answer 290

inducible Treg acts in concert with nTreg cells (naturally occurring Treg) and is responsible for restraining the immune response to prevent excessive immune responses

Answer 291

Like CD4+ cells, CD8+ cells also synthesise and express IL-2 receptors and release IL-2, which acts in an autocrine manner to generate cytotoxic T cells (TC), which kill virally infected cells.

Answer 292

Th1 responses Th2 response

Answer 293

Type 1 (insulin-dependent) diabetes mellitus, multiple sclerosis, rheumatoid arthritis and graft rejection

Answer 294

glucocorticoids is reserved for endogenous steroids that regulate glucose metabolism (e.g. cortisol), whereas corticosteroids includes both endogenous glucocorticoids and artificial steroids, such as prednisolone, that are used in therapy; mineralocorticoids are also a subclass of corticosteroids, but do not concern us here

Answer 295

in the adrenal cortex in response to circulating levels of adrenocorticotrophic hormone (ACTH, released from the pituitary gland)

Answer 296

under the control of corticotrophin-releasing factor (CRF, release from the hypothalamus) and one function of glucocorticoids is to inhibit CRF production and thus their own systemic levels as well

Answer 297

``` decreased uptake of glucose by muscle/fat (consider the impact for diabetic humans), increase gluconeogenesis, increased protein catabolism, decreased protein anabolism redistribution of fat ```

Answer 298

decrease: - influx/activity of leukocytes - activity of monocytes - clonal expansion of T and B cells - pro-inflammatory cytokine production/action (e.g. IL-1, IL-2, IL-5, TNF-α, etc.) - eicosanoid production increase - release of anti-inflammatory factors, e.g. IL-10, IL-1ra, lipocortin 1, annexin-A1 and IκB

Answer 299

to reduced activity of both the innate and adaptive immune response

Answer 300

the glucocorticoid receptor (GRα), which is a nuclear receptor.

Answer 301

GRα is present as homomers in the cytoplasm and are bound to heat shock protein 90 (Hsp90) and other proteins. Binding of ligand to the receptor causes dissociation of Hsp90 and enables ligand-bound GRα to form homodimers, which translocate to the nucleus and can either transactivate or transrepress a wide range of genes

Answer 302

GRα can regulate 1% of the total genome

Answer 303

A, GRα binds to a positive glucocorticoid response element (GRE) within a promoter region for a gene with low transcriptional activity and activates the transcriptional machinery (TM) B, the TM is constitutively driven by transcription factors (TF) and GRα binds to negative GREs (nGRE) causing TF displacement and repression of the TM; C, the TM is driven at a high level by Fos/Jun TFs binding to their AP-1 regulatory site, the effect of which is reduced by GRα binding D, the TFs P65 and P50 bind to the NFκB site promoting the TM, an effect that is prevented by prior binding of GRα.

Answer 304

hydrocortisone rapidly inhibits neutrophil degranulation and neither GRα antagonists nor inhibitors of translation prevent this phenomenon. IgE-mediated mast cell degranulation is rapidly inhibited by corticosteroids in a non-genomic manner, such that membrane impermeable versions of corticosteroids have identical effects to membrane permeable versions, i.e. binding to intracellular GRα is not required. in healthy human volunteers prone to allergic rhinitis, following induction of nasal irritation with a pollen suspension, betamethasone administration markedly reduced nasal itching within 10 minutes, the speed of this response cannot be explained by genomic effects.

Answer 305

- opportunistic infection - thinning of skin and impaired wound healing - candidiasis - osteoporosis - hyperglycaemia – because of glucose metabolism effects (particularly problematic in diabetic humans and animals) - muscle wasting - stomach ulcer - avascular necrosis of the femoral head (rare and idiosyncratic leading to a need for hip replacement) - adverse psychiatric effects, e.g. disturbed sleep and even psychosis

Answer 306

several reasons, including the reduced osteoblast/increased osteoclast activity

Answer 307

suppression of local anti-infective mechanisms when taken orally

Answer 308

a bisphosphonate (bone protection) a proton pump inhibitor (ulcer).

Answer 309

Cushing’s syndrome can develop

Answer 310

from an ACTH secreting tumour

Answer 311

in dogs receiving excessive corticosteroid treatment, or due to ACTH secreting tumours symptoms include: pot-bellied appearance, hair loss (primarily body, not face/legs), polydipsia and polyuria.

Answer 312

can result in acute adrenal insufficiency (Addisonian crisis as the patient fails to synthesise enough steroids (and hence patients carry a “steroid card”) withdrawal should thus be tapered to enable full HPA recovery and schedules are often patient specific.

Answer 313

hydrocortisone (name given to cortisol when used as a medication) is short acting <24hrs dexamethasone (for treating swelling and inflammation in metastatic cancer, ) is long acting with a biological half-life of >48hrs.

Answer 314

for treating swelling and inflammation in metastatic cancer, as well as to Covid-19 patients requiring supplemental oxygen and/or mechanical ventilation

Answer 315

eczema can be treated with a 1% hydrocortisone topical cream

Answer 316

reduce cerebral oedema in patients with brain tumours and those suffering from high altitude cerebral oedema

Answer 317

used to replace physiological levels of endogenous steroids in Addison’s disease (where the adrenal glands fail to produce sufficient steroid hormone)

Answer 318

autoimmune destruction of the adrenal cortex and infection of the adrenal glands by tuberculosis

Answer 319

In the UK, approximately 5.5 million people suffer from asthma, about 1 in 12 people

Answer 320

1) inflammation of the airways 2) bronchial hyper-reactivity (hypersensitivity to irritant chemicals, cold etc. and in allergic asthma, specific allergens) 3) reversible bronchoconstriction

Answer 321

a dendritic cell in the airway submucosa takes up an allergen and presents it to a CD4+ T cell, resulting in the development of a Th0 cell, which gives rise to Th2 Th2 cells: release IL-5 (eosinophil priming) and IL-4 and IL-13 (switch B cells/plasma cells into producing IgE) induce IgE receptor (FcεRI) expression in mast cells and eosinophils high circulating IgE levels also increase mast cell FcεRI expression

Answer 322

causes degranulation and release of histamine and CysLTs, which are both powerful bronchoconstrictors and increase vascular permeability – process is characteristic of the immediate/acute phase of an asthma attack

Answer 323

release IL-4, IL-5, IL-13 and TNFα, as well as a variety of chemotaxins that recruit both eosinophils and macrophages

Answer 324

smooth muscle hypertrophy occurs and the eosinophils recruited to the mucosal surface release CysLTs and granule proteins such as eosinophil cationic protein and eosinophil major basic protein which both damage the epithelium resulting in airway hypersensitivity

Answer 325

epithelial cell loss means that nociceptive C-fibres are more accessible to irritant stimuli, which is an important hypersensitivity mechanism

Answer 326

bronchodilators (predominantly for use in acute attacks) anti-inflammatories (to limit the inflammatory components of both acute and late phases), which are usually taken as prophylactics

Answer 327

not everyone but recommended recommended if a person experiences asthmatic symptoms/uses a bronchodilator more than twice a week, or wakes up once a week with asthmatic symptoms

Answer 328

starts with a short-acting inhaled β2-adrenoceptor agonist used as required (e.g. salbutamol), moving up to a regular inhaled corticosteroid (e.g. beclomethasone) to which a long-acting inhaled β2 agonist (LABA, e.g. formoterol) can be added, then the addition of either a CysLT1 receptor antagonist (e.g. montelukast), theophylline or oral LABA (each can be tried in turn) finally daily oral corticosteroids at the lowest dose that controls the asthma. Omalizumab can also be considered

Answer 329

act upon Gs-coupled β2-adrenoceptors expressed by bronchial smooth muscle to induce relaxation and bronchodilation and β2-adrenoceptors expressed by mast cells to inhibit degranulation

Answer 330

increase adenylate cyclase activity = increase cAMP/PKA = myosin light chain kinase phosphorylation and inactivation

Answer 331

salbutamol is a short-acting drug taken as needed to control symptoms, the maximum effect occurs within 30 minutes and the duration of action is 3-5 hours; formoterol is a LABA used prophylactically and has a duration of action of 8-12 hours.

Answer 332

because its long, lipophilic tail enables it to be incorporated into the plasma membrane, which acts as a drug reservoir, and in addition, the lipophilic tail binds to an extra binding site on the β2-adrenoceptor itself

Answer 333

tremor (excitation of β2-adrenoceptors in skeletal muscle) and tachycardia (excitation of facilitatory β2-adrenoceptors in cardiac noradrenergic nerve terminals).

Answer 334

yes | including the “ultra” long-acting β2-adrenoceptor agonist indacaterol

Answer 335

an inhaled corticosteroid, commonly used in the prophylactic treatment of asthma

Answer 336

action is genomic so are not useful reversing the acute bronchoconstriction during an asthma attack

Answer 337

when treating asthma, can be inhaled directly reduces side effect profile but oral candidiasis (thrush) infections can also occur

Answer 338

Beclomethasone can be combined with formoterol to lessen the number of inhalers used by patients

Answer 339

inhibits PDE to increase [cAMP] and therefore induces bronchodilation/mast cell stabilisation by the same mechanism as β2-adrenoceptor agonists

Answer 340

it is used prophylactically against asthma and not advised in treating acute attacks

Answer 341

commonly cardiovascular, e.g. tachycardia

Answer 342

is metabolised by CYP450, which can be induced/inhibited by many drugs

Answer 343

a CysLT1 receptor antagonist and can induce bronchodilation to treat asthma, less effective than salbutamol and is used prophylactically.

Answer 344

ipratropium (used in management of acute attacks)

Answer 345

a short-acting muscarinic antagonist produces bronchodilation by inhibiting M3 receptors on the smooth muscle

Answer 346

false Sodium cromoglycate is a mast cell stabiliser and can be used prophylactically in the treatment of allergic asthma where mast cells are key players in the pathology, such as in research scientists who develop allergies to laboratory animals.

Answer 347

humanised monoclonal Ab against IgE (5% mouse, 95% human sequence) recommended cases of severe, persistent allergic asthma that are refractory to treatment with corticosteroids and long-acting β2-adrenoceptor agonists.

Answer 348

humanised monoclonal Ab against IgE By binding to the Cε3 region of IgE (part of the heavy chain that binds to FcεRI), omalizumab prevents IgE binding to FcεRI, which reduces FcεRI expression and inhibits allergen induced mast cell degranulation

Answer 349

Omalizumab is built on an IgG framework

Answer 350

given as an injection every 2-4 weeks

Answer 351

only recommended for people who frequently suffer from severe allergic asthma attacks necessitating frequent hospital attendances, where other treatments have failed

Answer 352

Cats can also develop pulmonary conditions showing similarities to asthma and they, like humans, can be treated with β2-adrenoceptor agonist bronchodilators like salbutamol and corticosteroids, such as fluticasone – harder to administer to a cat than a human, but inventions like the AeroKat perhaps make it (slightly) easier.

Answer 353

Recurrent Airway Obstruction (RAO, or heaves), which can be treated with both bronchodilators (e.g. clenbutarol administered orally with feed) and corticosteroids (e.g. fluticasone). In contrast to treating humans, sodium cromoglycate has little efficacy, which likely reflects a more important role for neutrophils than mast cells in the pathophysiology of RAO.

Answer 354

chronic inflammation of the airways and lung tissue leading to narrowing of the airways and shortness of breath.

Answer 355

a) smoking | b) significant contribution from pollutants (e.g. smoke from cooking with wood with poorly ventilation).

Answer 356

asthma: characterised by activated mast cells and eosinophils COPD: enriched in neutrophils and macrophages + fibroblast proliferation (leading to small airway fibrosis)

Answer 357

fibroblast proliferation leading to small airway fibrosis (common in COPD) this is a stark contrast to the reversible inhibition seen in asthma

Answer 358

Whereas bronchial biopsies from asthmatics are characterised by activated mast cells and eosinophils, biopsies from those with COPD are enriched in neutrophils and macrophages airway narrowing is irreversible in COPD but reversible inhibition is seen in asthma Alveolar tissue damage is important in COPD but not asthma whereas small airway epithelial loss is common in asthma (leading to exposure of nociceptors), epithelial cells often proliferate in COPD

Answer 359

not particularly effective because of the limited reversible nature of the bronchoconstriction occurring in COPD They are not recommended for treatment on a regular basis, but can be used in acute exacerbations

Answer 360

the limited reversible nature of the bronchoconstriction occurring in COPD (remember, unlike in asthma that fibrosis also occurs and affects tissue elasticity).

Answer 361

yes: formoterol and indacaterol are used, often in combination with long-acting muscarinic antagonists (LAMAs, e.g. tiotropium, rather than short-acting ipratropium, which is used for treating milder COPD as determined by lung function tests)

Answer 362

in LABA-LAMA combination inhalers

Answer 363

different mechanisms of action leads to additive effects: LABA = β2-adrenoceptor activation = increase AC activity = increase cAMP/PKA = myosin light chain kinase phosphorylation and inactivation + LAMA = M3 inhibition = prevention of PLC activation and IP3 generation

Answer 364

they are largely ineffective, although are used in the treatment of acute exacerbations of COPD, for example when there is a coexistent infection, or where small airway inflammation is predominant

Answer 365

in COPD, there is a reduction in expression and activity of histone deacetylase 2 (HDAC2): superoxide (O2-) and nitric oxide (NO) produced from cigarette smoke and activated immune cells results in the formation of peroxynitrite (ONOO-), which nitrates HDAC2 at the active site leading to its inactivation, ubiquitination and degradation. With lowered levels of HDAC2, there is increased acetylation of GRα, which prevents it from inhibiting NFκB-driven inflammation.

Answer 366

Reversing corticosteroid resistance

Answer 367

yes: used as a sustained release preparation to treat COPD

Answer 368

bronchodilator effects (due to increased cAMP levels) raises cAMP levels in neutrophils and other immune cells causing a decrease in chemotaxis and activation

Answer 369

PDEIV (also main PDE expressed in neutrophils, T cells, ad macrophages) neutrophils highly expressed in COPD specific PDEIV inhibitor roflumilast is approved for treating COPD; it is used as an add on therapy to LABAs.

Answer 370

for those with low blood O2 levels, long-term O2 therapy is used sometimes only necessary during exercise NOT for smokers

Answer 371

O2 and cigarettes do not mix: home O2 therapy should not be prescribed to patients who continue to smoke

Answer 372

when O2 therapy is only necessary during exercise

Answer 373

modulation of neutrophil chemotaxis anti-fibrotic therapy, inhibition of elastase activity

Answer 374

initial trials with CXCR2 antagonists were promising, but were discontinued when larger trials produced negative results

Answer 375

elastase elevated in COPD and may contribute to the development of emphysema

Answer 376

Graves' disease (autoantibodies activate the thyrotropin receptor causing increased thyroxine release) Hashimoto's disease (autoantibodies against proteins involved in thyroxine synthesis, e.g. thyroglobulin; this typically leads first to hyperthyroidism due to cell death and release of thyroxine, followed by hypothyroidism as thyroxine supplies are exhausted and not replaced)

Answer 377

autoantibodies against the nicotinic receptor that prevent the effects of acetylcholine

Answer 378

- primary biliary cirrhosis -> immune attack against bile ducts of the liver) - rheumatoid arthritis -> immune attack on the synovium surrounding joints

Answer 379

1% one third of whom were likely to become severely disabled due to joint damage, prior to the development of disease modifying therapies

Answer 380

a combination of factors that are driven by activated Th1 cells: macrophages are stimulated to release IL-1 and TNFα causing release of metalloproteinases from osteoclasts and fibroblasts that cause cartilage and bone destruction, an effect exacerbated by infiltrated inflammatory cells, e.g. neutrophils release proteases and ROS that both cause damage. Hyperplasia of the synovium also occurs resulting in pannus formation as fibroblast-like synoviocytes proliferate and invade the joint and release proinflammatory cytokines and proteases.

Answer 381

some treat only the symptoms, whereas others reduce disease progression, so-called disease-modifying antirheumatic drugs (DMARDs).

Answer 382

used to relieve pain and lessen inflammation but do not alter the underlying disease process

Answer 383

Diclofenac (or the misoprostol combination drug Arthrotec) has largely been superseded by naproxen etorixcoxib

Answer 384

lower cardiovascular risk COX2 selective so significant reduction in risk of GI bleeding

Answer 385

prednisolone (provides symptomatic relief and suppresses disease activity) Due to the side-effects associated with systemic/chronic corticosteroid use, they are usually only used to treat disease flare-ups, or as a bridging therapy when waiting for a DMARD to take effect

Answer 386

decreased transcription of IL-2, which is important for driving Th cell proliferation, and the decreased transcription of IL-1/TNFα

Answer 387

orally | can also be delivered locally, i.e. intra-articular injections

Answer 388

methotrexate can be used alone or in combination with other DMARDs

Answer 389

folic acid inhibition lowering the production of tetrahydrofolate that is required for purine nucleotide and thymidylate synthesis and thus is anti-proliferative, reducing the immune response

Answer 390

inhibition of dihydrofolate reductase and competition with folic acid transport into cells

Answer 391

3--12 weeks orally to be taken once a week, but can also be administered by weekly subcutaneous injection; weekly administration is important (NOT daily)

Answer 392

bone marrow suppression and GI disturbance weekly folic acid supplement

Answer 393

incorrect daily administration of methotrexate is a recognised prescribing error that can prove fatal due to the profound effects on bone marrow suppression and impairment of immune system function

Answer 394

Sulfasalazine

Answer 395

taken orally daily broken down by colonic bacteria to produce sulfapyridine (a sulphonamide) and 5-aminosalicylic acid (a salicylate) and one likely MOA is that the 5-aminosalicylic acid scavenges ROS released from neutrophils

Answer 396

not until after 3 months

Answer 397

``` GI disturbances, skin rashes, bone marrow suppression hepatotoxicity tears and contact lenses can be stained yellow urine may appear orange ```

Answer 398

malaria (also now used as a DMARD)

Answer 399

As a lipophilic weak base, hydroxychloroquine accumulates in cytoplasmic acidic vesicles, which can reduce antigen presentation by macrophages and reactive oxide species generation in neutrophils

Answer 400

``` ocular toxicity, GI upset, skin reactions, seizures, myopathy, psychiatric disturbance. ```

Answer 401

inhibits dihydroorotate dehydrogenase, a key enzyme in pyrimidine synthesis, and thus it inhibits synthesis of DNA and RNA, with its main effect being on rapidly dividing cells such as B and T cells.

Answer 402

RA Adverse effects include GI disturbance, bone marrow suppression and hepatotoxicity.

Answer 403

biological DMARDS (Anti TNFα therapies, Anti-IL-6 therapy, Anti-B cell therapy, Anti-T cell therapy, Anti-IL-1 therapy) as combination treatments with methotrexate

Answer 404

Etanercept Infliximab adalimumab

Answer 405

a fusion protein of the soluble TNFα receptor and the Fc portion of IgG1, which acts to mop up the high levels of TNFα that occur in RA

Answer 406

monoclonal anti-TNFα antibodies (mAb, chimeric and human respectively) that, like etanercept, sequester TNFα.

Answer 407

allergic reactions, bone marrow suppression, increased susceptibility to infections (particularly tuberculosis and hepatitis B reactivation) MS

Answer 408

several cases of multiple sclerosis have been reported in patients following anti-TNFα treatment for inflammatory arthritis

Answer 409

Tocilizumab (a mAb) targets the IL-6 receptor, inhibiting the action of IL-6.

Answer 410

IL-6 is a pro-inflammatory cytokine and, like TNFα and IL-1 is upregulated in RA. IL-6 also drives the production of c-reactive protein (CRP), which is commonly measured in blood tests, and so tocilizumab tends to be targeted towards patients with significantly elevated levels of CRP.

Answer 411

rituximab (a mAb)

Answer 412

CD20 that is primarily expressed by B cells, can be used in the treatment of RA, its therapeutic effect being through B cell destruction.

Answer 413

increased risk of infection (like all DMARDs) especially, an increased risk of a potentially fatal brain infection called progressive multifocal leukoencephalopathy, which is caused by reactivation of the John Cunningham (JC) virus.

Answer 414

abatacept a synthetic fusion protein of the costimulatory cytotoxic T-lymphocyte protein 4 (CTLA-4) and the Fc fragment of human IgG1

Answer 415

binds to CD80 and CD86 on antigen presenting cells, so interferes with the ability of antigen presenting cells to activate T cells

Answer 416

anakinra a recombinant version of the IL-1 receptor antagonist, which binds to the IL-1R with a higher affinity than IL-1 itself, but does not initiate receptor signalling

Answer 417

On the balance of clinical benefits and cost-effectiveness, it is not recommended for treatment of RA in the UK, but is used in other countries

Answer 418

although usually reserved for treating certain forms of cancer methotrexate can also be used to treat dogs with arthritis.

Answer 419

NSAIDs and corticosteroids

Answer 420

All biological DMARDs are given by injection, either intravenous or subcutaneous, all are expensive. They are all associated with an increased risk of infections. Each class has similar efficacy, but failure to respond to one class does not determine response to another class, so they tend to be tried serially

Answer 421

the immune system is compromised and thus less able to respond to infection

Answer 422

azathioprine methotrexate mycophenolic acid.

Answer 423

via decreasing the transcription of a variety of cytokines, including those that drive Th cell proliferation and those that drive inflammatory responses, (e.g. IL-1 and TNFα), while at the same time upregulating anti-inflammatory factors such as IL-1ra

Answer 424

IL-2 which causes generation and proliferation of Th0 cells and proliferation of Th0 cells into Th1 cells

Answer 425

is a prodrug for 6-mercaptopurine (6-MP), which is converted to thioinosic monophosphate (TIMP), which is converted by two different enzymes to produce two products that inhibit DNA function: Thiopurine methyltransferase (TPMT) converts TIMP to 6-methyl-TIMP (MeTIMP), which inhibits de novo purine synthesis and inosine monophosphate dehydrogenase (IMPDH) converts TIMP to 6-thioguanosine nucleotides (6-TGN), which are incorporated into cellular nucleic acids resulting in inhibition of nucleotide and protein synthesis

Answer 426

by hypoxanthine phosphoribosyl transferase (HPRT)

Answer 427

inhibits cellular proliferation has a greater effect upon rapidly proliferating cells, such as T cells and B cells when activated, and thus azathioprine inhibits T cell and B cell proliferation making it a useful drug in preventing transplant rejection and autoimmunity

Answer 428

IBS RA graft rejection

Answer 429

effects include GI upset, hepatotoxicity and bone marrow depression (you can also get accumulation of cytotoxic 6-thioguanine nucleotide analogues leading to toxicity)

Answer 430

10% TPMT levels vary, 10% of people having very low activity and thus accumulation of cytotoxic 6-thioguanine nucleotide analogues leading to toxicity by checking TPMT levels, or close monitoring of blood counts/liver function on starting treatment

Answer 431

yes as an immunosuppressant

Answer 432

true targets rapidly proliferating cells, such as those of the immune system. It is used in the treatment of many autoimmune conditions such as RA

Answer 433

derived from the fungus Penicillium stoloniferum, which inhibits IMPDH, an enzyme crucial for de novo guanosine synthesis (so has greatest effect on rapidly dividing B and T cells)

Answer 434

used to diminish transplant rejection but also used in autoimmune diseases such as myasthenia gravis.

Answer 435

a prodrug, being converted by hepatic P450 enzymes first to aldophosphamide and then the active phosphoramide mustard (alkylating agent)

Answer 436

has two alkylating groups and cross links guanine in DNA via N7 groups bischloroethylamine undergoes cyclisation, releasing Cl- and forms an unstable immonium cation, the strained ring opens to form a reactive cabonium ion, which reacts with guanine’s N7 to produce 7-alkylguanine. DNA replication is thus defective because 7-alkylguanine pairs with thymine producing substitution of A-T for G-C, it can also cause guanine excision and chain breakage. immunosuppressive effect is due to killing of dividing T and B cells, but this occurs alongside side effects: bone marrow depression, potential infertility, bladder irritation and cancer

Answer 437

its metabolite acrolein activates TRPA1 expressed by bladder innervating nociceptors, acrolein is also present in cigarette smoke and some forms of tear gas

Answer 438

used to treat refractory autoimmune conditions and some cancers

Answer 439

Ciclosporin A | an immunosuppressive isolated from the fungus Tolypocladium inflatum

Answer 440

a cyclic, 11 amino acid peptide predominant action is to prevent T-cell proliferation via suppression of IL-2 synthesis.

Answer 441

increase in [Ca2+]i that stimulates the activity of a serine-threonine phosphatase called calcineurin (CaN), which then dephosphorylates the nuclear factor of activated T-cells (NF-AT) enabling its translocation to the nucleus and consequent upregulation of IL-2 transcription CsA binds to a cytoplasmic protein called cyclophilin (CpN), which is member of the immunophilin group of proteins. The CsA-CpN complex binds to and inhibits CaN, which thus prevents NF-AT dephosphorylation and it is retained in the cytoplasm preventing IL-2 upregulation and is thus used in suppressing the rejection of transplanted organs

Answer 442

atopic dermatitis

Answer 443

FK506 macrolide antibiotic produced by Streptomyces tsukubaensis, which binds to an immunophilin called FKBP

Answer 444

the complex inhibits CaN (similar to the action of the CsA-CpN complex) thus thus NF-AT is retained in the cytoplasm and IL-2 synthesis is inhibited

Answer 445

transplant rejection

Answer 446

a monoclonal antibody against the CD25 alpha subunit of the IL-2 receptor and thus functions as an IL-2 receptor antagonist

Answer 447

it is an IL-2 receptor antagonist. IL-2 receptors are upregulated on activated T-cells and B-cells so basiliximab decreases the incidence and severity of acute rejection following transplantation.

Answer 448

belatacept

Answer 449

fusion protein of the extracellular domain of cytotoxic T-lymphocyte protein 4 (CTLA-4) and the Fc fragment of human IgG1

Answer 450

2 signals: 1) interaction between the major histocompatibility complex (MHC) of the APC with the T cell receptor and 2) interaction between CD80/86 ligands of the APC with CD28 of the T cell Belatacept - acts to bind CD80/86 and prevent T cell costimulation

Answer 451

its activation by CD80/86 sends an inhibitory signal to the T cell has 2 amino acid variations that confer greater affinity for, and slower dissociation from, CD80/86

Answer 452

used in combination with other drugs to prevent graft transplant rejection

Answer 453

can cause activation and proliferation of regulatory T cells, which are involved in preventing autoimmune reactions an anti-CD28 agonist monoclonal antibody TGN1412 was trialled following promising results from non-human animal tests, but was abruptly ended after causing a cytokine storm in humans due to its activating effects being non-selective, i.e. in humans at the dose used pro-inflammatory memory T cells were activated alongside regulatory T cells

Answer 454

maybe but must be administered at lower doses than in original trial to enable selective activation of Treg cells

Answer 455

sirolimus a macrolide antibiotic produced by Streptomyces hygroscopicus, which like tacrolimus binds to FKBP and inhibits mTOR

Answer 456

both bind to FKBP but sirolimus-FKBP inhibits mTOR whereas tacrolimus-FKBP inhibits CaN

Answer 457

mammalian target of rapamycin (mTOR), which is a serine/threonine kinase involved in cell cycle progression and protein synthesis mTORC1 (mTOR complex 1)

Answer 458

binds FKBP, forming a complex which inhibits mTOR, inhibiting mTORC1 especially. this leads to decreased T cell activation and proliferation and a decreased immune response

Answer 459

prevent transplant rejection used to coat coronary stents to prevent restenosis (thanks to its antiproliferative effects)

Answer 460

host organism can be injected with an antigen (e.g. inactivated bacterial toxin), serum extracted from the host would contain antibodies against the antigen, but they would be a mixture of antibodies because numerous plasma cells react to a particular antigen and produce different antibodies

Answer 461

Each serum generated in this manner will be of variable potency and there is only so much serum that can be collected

Answer 462

for generating antibodies for the lab, one standard protocol involves injecting two rabbits with antigen and collecting a total of 75 ml/rabbit over 70 days

Answer 463

fusing single mouse B-cells with immortalised tumour cells to produce a hybridoma that could grow indefinitely to produce a single antibody

Answer 464

mAbs have known potency and there is no limitation to the amount that can be produced.

Answer 465

Mice are firstly injected with an antigen and antibody producing B cells are isolated from the spleen, these are then mixed with myeloma cells (HPRT-ve) in polyethylene glycol to produce hybridomas; hybridomas are selected by growing in a medium containing a dihydrofolate reductase inhibitor, which kills off unfused myeloma cells, whereas hybridomas can create new nucleotides from supplements in the medium because they express B cell HPRT, unfused B cells have a short life and die off. B cells are then screened for specificity (e.g. using an ELISA) and then using limiting dilution individual cells/clones are isolated, which can be propagated and then mAb collected

Answer 466

2 key domains: Fc region - reacts with cell surface Fc receptors that are expressed by neutrophils (FcγRI, respiratory burst and phagocytosis), macrophages (FcγRII, phagocytosis) and natural killer cells (FcγRIII, antibody-dependent cell-mediated cytoxicity, ADCC) Fab- contains the variable and hypervariable regions (also known as the complementarity determining regions, CDR), which bind the antigen in question

Answer 467

a mouse injected with, for example, human TNFα will make mouse antibodies (which can be isolated as mAbs using hybridoma technology) and thus when injected into humans they were observed to produce an immune response in over half of recipients because of the generation of human anti-mouse antibodies relatively low circulatory half-life unable to activate human complement

Answer 468

murine mAb that targets CD3 was the first mAb to be approved for clinical use in humans to reduce acute transplant rejection

Answer 469

Using recombinant DNA technology, the first strategy was to create chimeric mAbs that contained the human Fc region, but mouse variable region (e.g. infliximab). Next, humanised mAbs were developed where only the CDR was of mouse origin and these produce very little immune response (e.g. omalizumab, alemtuzumab and rituximab)

Answer 470

In both chimeric and humanised mAbs, the presence of the human Fc region lengthens the plasma half-life because they can bind to neonatal Fc receptor (FcRn) on endothelial cells and are recycled.

Answer 471

either by using transgenic mice in which the mouse immunoglobulin genes are swapped with the human equivalents, or through phage display adalimumab

Answer 472

By injection every 2 weeks (although this differs greatly e.g., infliximab is administered every 2 weeks and others once per month)

Answer 473

Due to their high specificity, there are few off-target effects, but mAbs that target functioning of the immune system can precipitate latent disease or encourage opportunistic infections.

Answer 474

binds to CD52, an antigen on mature lymphocytes, but not the stem cells from which they derive, and targets them for destruction used in treating chronic lymphocytic leukaemia, cutaneous T cell lymphoma, T cell lymphoma and multiple sclerosis

Answer 475

- ximab = chimeric -axomab = rat/mouse hybrid -zumab = humanised –umab = human

Answer 476

false (but used to be true) Nexvet used a process called PETization to make canine, feline and equine mAbs and was bought out by Zoetis, who have marketed an anti-IL-31 mAb for treating dermatitis in dogs. Publications suggest that anti-NGF mAbs are in late-stage development for treating chronic pain such as that experienced in feline/canine osteoarthritis.

Answer 477

involve stitching together two halves of different antibodies, the idea is that one antibody binds the target cell and the other binds a cytotoxic cell, i.e. the killing machinery is localised to the target

Answer 478

catumaxomab a rat/mouse hybrid mAb that binds epithelial cell adhesion molecule and CD3 on tumour cells and T cells respectively leading to the destruction of the cancer cell

Answer 479

ascite in cancer patients

Answer 480

the Fc portion can bind the Fc receptors on macrophages etc

Answer 481

one that can sequester two molecules simultaneously, e.g. TNFα and IL-1.

Answer 482

most antibodies and serum IgG are fucosylated, but antibodies engineered to be afucosylated have a higher affinity for the FcγRIII on NK cells and overcome competition with serum IgG thus increasing the window of time for ADCC to occur.

Answer 483

Fucosylated Fc causes displacement of the oligosaccharide tree connected to Asn162 of FcγRIII, which leads to an increased distance of the carbohydrate-carbohydrate contact between Fc and FcγRIII and thus reduced bond strength that explains the reduced affinity of fucosylated Abs

Answer 484

false afucosylated Fc Abs can outcompete fucosylated, serum IgG Fucosylated Fc causes displacement of the oligosaccharide tree connected to Asn162 of FcγRIII, which leads to an increased distance of the carbohydrate-carbohydrate contact between Fc and FcγRIII and thus reduced bond strength

Answer 485

trastuzumab used to treat HER2 positive breast cancers yes but resistance often arises

Answer 486

Trastuzumab emtansine (T-DM1) is a combination of trastuzumab (T) with a derivative of the antimicrotuble compound maytansine (DM1). Binding of T-DM1 to HER2 causes internalisation, lysosomal degradation and release of DM1, which can bind to tubulin and prevent polymerisation causing cytotoxicity; T-DM1 also retains the basic actions of trastuzumab: disruption of HER2 signalling and targeting tumour cells for ADCC

Answer 487

improved pharmacokinetics by mutation of the Fc region to improve binding to FcRn at low pH so that more is recycled out of cells and not broken down by intracellular degradation machinery. Fc portion of IgG binds FcRn with high affinity at acidic pH (e.g. in endosome), but lower affinity at physiological pH, increasing this affinity further would increase the circulation time.

Answer 488

diffusion into tissues is slow and access to intracellular targets is problematic

Answer 489

shrink the peptide scaffold that displays the antigen binding loops create bicyclic peptides, which due to their rigid conformation can bind with high affinity and specificity to protein targets, but are more resistant to serum proteases than linear peptides creation of nanobodies

Answer 490

the isolated variable heavy chains, containing the CDRs, from Abs produced by camelidae and certain cartilaginous fish - they are single domain abs with low Mr

Answer 491

+larger loops in camelidae CDRs enables greater antigen-interacting surface than heavy chain CDRs from standard IgG Abs. +a low molecular weight (~12-15 kDa vs. ~150 kDa of conventional mAbs) means they are likely to have better tissue permeability and tissue penetration - also means they have a lower plasma half-life

Answer 492

a degenerative joint disease

Answer 493

Unlike RA, osteoarthritis (OA) is not an autoimmune condition, but rather a degenerative joint disease that sometimes occurs as a consequence of rheumatoid arthritis

Answer 494

degenerative joint disease (DJD).

Answer 495

disruption of the equilibrium between cartilage breakdown and repair, which results in a net loss of articular chondrocytes

Answer 496

true however, this does not mean everyone will develop OA

Answer 497

age – onset is most common from late 40s onwards, gender – OA is more common in women than men, obesity – increased weight bearing is a key factor in OA of the knee, and joint injury/abnormality

Answer 498

usually a consequence of a developmental orthopaedic disease, such as hip dysplasia (very much breed specific, and if I had a choice I would rather be born a whippet, 1.0% dysplastic, than a pug, 71.7% dysplastic) although the aetiology is less well understood in cats the degenerative process itself is similar to that observed in other species and affects similar joints to as in dogs, i.e. hips, stifle and elbow.

Answer 499

bone remodelling

Answer 500

early-stage OA is associated with thinning of the subchondral plate, but in late-stage disease there is a decrease in bone resorption, but no decrease in bone formation leading to the development of subchondral sclerosis (increased bone density) and bony outgrowths at joint margins called osteophytes

Answer 501

often inflamed , sometimes being observed in early-stage, late-stage or both stages of OA

Answer 502

no despite inflammation of the synovium it is considered non-inflammatory because the synovial fluid typically contains a lower leukocyte count than that which defines an inflammatory condition

Answer 503

decreased range in joint movement and pain

Answer 504

true | globally ~20% of chronic pain is related to OA.

Answer 505

NO CURE but NSAIDs used for pain control and corticosteroids can be used further analgesia may be necessary depending upon the level of pain

Answer 506

a) e.g. diclofenac and etoricoxib | b) e.g. robenacoxib

Answer 507

capsaicin activates TRPV1 expressed by nociceptors and constant presence of the agonist (after an initial warming sensation) causes depolarising block of nociceptors, as well as nociceptor degeneration (depending on the concentration used), leading to pain relief

Answer 508

Capsaicin creams can be applied to the affected area 3-4 times a day in humans intra-articular injection of TRPV1 agonists has been successfully trialled in dogs

Answer 509

osteoarthritic synovitis is associated with raised levels of IL-1, IL-6 and TNFα unfortunately related treatments used to treat RA are largely ineffective

Answer 510

IL-1 receptor antagonist protein - used to treat OA in horses

Answer 511

: blood is collected from a horse into a syringe with glass beads coated in a way that induces IRAP production, 24-hours later serum containing IRAP is collected and can be stored at -80°C and injected into affected joints (of the same horse!) when needed.

Answer 512

NGF, which causes pain tanezumab - an anti-NGF mAb

Answer 513

looks efficacious compared to other treatments, but concerns remain with regard to increased observation of rapidly progressing OA in patients treated with tanezumab compared to controls.

Answer 514

- autologous chondrocyte implantation/ transplantation - injection of mesenchymal/bone marrow-derived stem cells - arthroplasty (joint replacement) in severe cases - possibly glucosamines and chondroitin supplements

Answer 515

collecting healthy cartilage tissue, isolating chondrocytes and implanting them into the damaged area

Answer 516

both procedures reduce pain and increase function although the latter is very much in the trial phase

Answer 517

they are constituents of joint cartilage trial data indicates that these supplements are safe to take, but little convincing evidence that they reduce pain, or impact the joint infrastructure compared to placebo

Answer 518

an autoimmune condition that occurs in two main forms, discoid lupus, which only affects the skin, and systemic lupus erythematosus (SLE), which affects skin and joints and frequently involves internal organs (e.g. heart and kidneys)

Answer 519

wide range of symptoms

Answer 520

cardiovascular problems eg patients often suffer from pericarditis (inflammation of the pericardium) and pleurisy with accelerated atherosclerosis also common in SLE

Answer 521

pains, rashes (especially over parts of the body exposed to the sun) extreme fatigue fever swelling of the lymph glands

Answer 522

9:1 those of child bearing age

Answer 523

although SLE runs in families, no single gene has been identified as causal, but susceptibility genes are known. Similarly, numerous environmental triggers are associated with SLE, e.g. UV radiation and viral infectio

Answer 524

defective clearance of apoptotic cells, increased response to antigens containing nucleic acids increased levels of several cytokines including: TNFα, IL-6, interferons and B lymphocyte stimulator (BLyS) decreased NET degradation a decreased threshold for activation of autoantibody producing B cells

Answer 525

defective clearing of apoptotic cells by macrophages results in APCs presenting apoptotic material as autoantigens, which results in the development of anti-nuclear antibodies (ANA) provide a further source of common SLE autoantigens such as histones

Answer 526

physical examination, | blood tests against ANA and anti-dsDNA.

Answer 527

B lymphocyte stimulator important for B cell survival, differentiation and antibody production

Answer 528

NO but treatments available have markedly changed life expectancy from ~5 years after diagnosis in the 1950s to today where >80% can expect to live a normal lifespan

Answer 529

- NSAIDs such as diclofenac to reduce joint pains and fever - hydroxychloroquine reduces inflammation, likely via reducing interferon production - corticosteroids to reduce inflammation during a flare-up - immunosuppressants like methotrexate and azathioprine - rituximab, anti-CD20 on B cells thus causing B cell destruction (limited trial evidence, likely resulting from there being multiple B cell subsets, perhaps CD20+ve are not that important in SLE) - belimumab – anti-BLyS, sequestration of BLyS reduces B cell activity

Answer 530

e.g. etanercept and infliximab, discontinuation of use usually reverses the symptoms.

Answer 531

genetic predisposition such that German shepherds and Shetland sheepdogs are most affected similar to in humans, with skin, joints and internal organs being affected and diagnostic tests also involve an anti-nuclear antibody test.

Answer 532

yes but rarely

Answer 533

As in humans, corticosteroids can be used, as can immunosuppressive therapies such as azathioprine.

Answer 534

pancreas (islets of Langerhans)

Answer 535

a) glucagon is released from α-cells to induce hepatic glycogenolysis (breakdown of stored liver glycogen to glucose) and gluconeogenesis, and lipolysis in fat b) a rise in blood glucose causes insulin release from β-cells

Answer 536

Insulin binds to the insulin receptor (a RTK) causing tyrosine autophosphorylation and binding via SH2 domains to insulin receptor substrate-1 (IRS-1), IRS-1 is phosphorylated and interacts with SH2-domain containing proteins such as PI3K

Answer 537

all increase apart from hepatic gluconeogenesis and glycogenolysis

Answer 538

Glucose enters β-cells via the glucose transporter GLUT2 and is metabolised to ATP. β-cells express ATP-sensitive K+-channels (KATP, i.e. ATP binding = inhibition), which are usually open and contribute to the resting membrane potential: K+ moves out of cells down its concentration gradient. KATP closure increases intracellular [K+], depolarisation activates CaV Ca2+ influx induces fusion of insulin containing vesicles: insulin is released

Answer 539

octameric containing a core of 4 inwardly rectifying K+ channel subunits, Kir6.2, which form the pore of the ion channel, and surrounding this are 4 sulphonylurea receptor 1 (SUR1) subunits. ATP binds to the Kir6.2 subunits to induce channel closure and β-cell depolarisation.

Answer 540

10% presents in childhood (peak incidence at age of 9-14); onset can be rapid and potentially life threatening if left untreated.

Answer 541

typically aged 40+, although this varies depending upon ethnicity, and unlike Type 1 DM the condition generally develops slowly

Answer 542

Excess glucose in the blood results in urinary excretion of glucose (glycosuria) producing osmotic diuresis and excessive urination (polyuria), dehydration, thirst and increased drinking (polydipsia)

Answer 543

Reduced insulin function also increases breakdown of protein and fat, which leads to weight loss and the increased production of ketoacids from lipid can result in diabetic ketoacidosis

Answer 544

neuropathy and damage to blood vessels, which can lead to blindness (diabetic retinopathy), nephropathy and an increased risk of cardiac/cerebral infarct, gangrene and limb amputations

Answer 545

the prevalence ranges from 0.03 – 1.3% and the fact that it occurs in certain breeds (e.g. pugs, Samoyeds and Swedish elkhounds) more than others (e.g. boxers and collies) suggests a genetic component

Answer 546

. Most dogs have a form of diabetes similar to Type 1 DM in humans, i.e. autoimmune β-cell destruction, but onset tends to be in older dogs as opposed to young humans. Dogs also present with DM that is more similar to human Type 2 DM, but obesity does not appear to be a clear-cut risk factor, although larger epidemiological studies are likely needed

Answer 547

nearly all cases observed are Type 2 DM with males being more likely to be diabetic than females, certain breeds are more susceptible (e.g. Burmese vs. Persian) and as in humans obesity is a clear risk factor

Answer 548

51-amino acid protein consisting of 2 polypeptide chains (A and B) linked by disulphide bonds

Answer 549

injection - usually subcutaneously, but intravenous administration can be used in hospital

Answer 550

Oral administration would result in too low bioavailability due to destruction in the GI tract

Answer 551

bovine/porcine insulin were once used they had potential to induce an immune response

Answer 552

Recombinant human insulin greater quality consistency no immune response

Answer 553

forms hexamers, which then dissociate to be absorbed into the blood stream

Answer 554

- fast-acting, e.g. insulin lispro - short-acting, e.g. insulin actrapid - intermediate-acting, e.g. Neutral Protamine Hagedorn (NPH) insulin - long-acting, e.g. glargine

Answer 555

insulin lispro analogue swapping of a lysine and proline residue towards the end of the C-terminus of the B chain this reduces dimer and hexamer formation, i.e. larger amounts of the active monomeric insulin are available after injection; onset after s.c. injection within 5-15 minutes, duration 4-6 hours

Answer 556

insulin actrapid human sequence with onset after sc injection within 30-60 minutes, duration 8-10 hours

Answer 557

intermediate acting insulin a suspension of protamine polypeptide and insulin, which forms relatively insoluble crystals thus slowing absorption onset within 2-4 hours, duration up to 12-18

Answer 558

glargine amino acid changes to the A and B chains change the molecule’s isoelectric point to a more neutral pH. When injected subcutaneously glargine forms a microprecipitate of stable hexamers and higher aggregates, which retard and prolong absorption

Answer 559

onset within 2-4 hours, duration 20-24 hours

Answer 560

can be combined into various dose regimens, e.g. once daily injection of a long-acting insulin at night and multiple injections of fast-acting insulin before eating or injection of a fast- and intermediate-acting insulin twice daily (available as pre-mixed preparations in fixed ratios) before breakfast and the evening meal

Answer 561

infuse fast-acting insulin continuously into subcutaneous tissues

Answer 562

In dogs and cats insulin must of course be administered by the owner, this is usually twice daily in cats and once/twice daily in dogs with monitoring of blood glucose as in humans

Answer 563

unpleasant and can be dangerous and may be initially signalled by trembling and sweating followed by confusion and irritability (in humans or animals alike!) and potentially resulting in drowsiness and coma.

Answer 564

by eating/drinking something sugary or intravenous glucose or glucagon by injection if unconscious

Answer 565

lipodystrophy at the site of injection, which can take the form of lipohypertrophy (fat build up due to local anabolic action of insulin) lipoatrophy (fat loss, likely resulting from an immune response and is far less common with recombinant forms of insulin), allergic reactions to insulin/additives can also develop.

Answer 566

many still have the potential to and treatments are aimed at enhancing insulin release or increasing insulin sensitivity

Answer 567

it can be if body's insulin production / sensitivity are inadequate but is rarely first line treatment

Answer 568

no . In some cases changes to diet and level of exercise alone can be sufficient to prevent any need for pharmacological treatment, many studies show that exercise increases insulin sensitivity through a number of mechanisms

Answer 569

insulin-stimulated PI3K activation is increased in human skeletal muscle, which results in increased GLUT4 expression (GLUT4 transports glucose into skeletal muscle) thus facilitating insulin-mediated glucose uptake.

Answer 570

increase glucose uptake in skeletal muscle, decrease hepatic gluconeogenesis, decrease intestinal carbohydrate absorption, decrease circulating levels of VLDL and LDL considering the fact that many Type 2 diabetics are overweight, an added bonus is decreased appetite

Answer 571

. Activation of AMPK decreases expression of genes involved in hepatic gluconeogenesis

Answer 572

GI disturbances lactic acidosis -metformin inhibits hepatic lactate uptake and thus people susceptible to lactate build up Importantly, metformin does not cause hypoglycaemia

Answer 573

those experiencing renal dysfunction or alcoholics as it makes patients susceptible to lactate build up

Answer 574

glibenclamide | glipizide

Answer 575

bind to the SUR1 subunit of KATP channels in pancreatic β-cells causing closure of the channel, triggering depolarisation, Ca2+ influx and insulin release (thus only useful to someone who has β-cells )

Answer 576

well absorbed, peak plasma concentrations are reached within a few hours and the duration of action is up to 24 hours.

Answer 577

glipizide is mainly metabolised in the liver to inactive products and excreted in the urine there is significant conversion of glibenclamide to active products in the liver before urinary excretion, therefore in people with renal inefficiency (i.e. the elderly) the action of glibenclamide is potentiated

Answer 578

pregnant women (SUs cross the placenta and enter breast milk) people who do not have beta cells

Answer 579

can evoke hypoglycaemia and also tend to increase appetite and thus cause weight gain. Blockade of cardiac KATP could be a potential issue

Answer 580

Blockade of cardiac KATP could be a potential issue, but the SUR2A subunit, not SUR1, is expressed in the heart and SUs show slightly higher affinity and efficacy at SUR1 containing KATP channels than SUR2A containing KATP channels

Answer 581

repaglinide, also inhibit KATP by binding to SUR1 like SU drugs

Answer 582

both inhibit KATP by binding to SUR1 meglitinides have faster onset and offset kinetics than SUs meaning that they are often taken just before a meal and are less likely to cause hypoglycaemia

Answer 583

Glucagon-like insulinotropic peptide (GIP) - from K cells glucagon-like peptide-1 (GLP-1) - from L cells

Answer 584

stimulate insulin secretion and inhibit glucagon secretion, as well as reducing gastric emptying thus slowing the rate of food absorption. GLP-1 also acts in brain to reduce appetite and thus reduces body weight

Answer 585

Both GLP-1 and GIP are broken down by dipeptidyl peptidase-4 (DPP-4)

Answer 586

a synthetic version of exendin-4, a peptide found in the saliva of the Gila monster (Heloderma suspectum) and mimics the effect of GLP-1 but is longer acting

Answer 587

Exenatide is injected subcutaneously and being more stable than GLP-1 can be administered twice daily, but a long release formulation enabling a weekly injection is also available and oral preparations are in phase 3 clinical trials.

Answer 588

a class of drugs called gliptins, e.g. sitagliptin

Answer 589

taken orally in combination with other drugs

Answer 590

SGLT1 allows absorption of glucose in the small bowel and SGLT2 is responsible for reabsorption of glucose filtered in the kidneys at the PCT

Answer 591

inhibit either SGLT2 (e.g. dapagliflozin) or combined SGLT1/2 inhibition

Answer 592

predominantly increase urinary glucose loss (and thus loss of calories so also allow weight loss), but also reducing GI glucose absorption.

Answer 593

efficacy is reduced where renal function is reduced due to less glucose in PCT to be excreted. Side effects are increased urinary and genital infections, increased urinary frequency and an as yet unexplained increase in ketone production in the liver

Answer 594

pioglitazone activate the peroxisome proliferator-activated receptor γ (PPARγ), a transcription factor highly expressed in adipose tissue, but also present in liver and muscle. PPARγ activation increases lipogenesis, glucose/fatty acid uptake and increases transcription of numerous genes including GLUT4.

Answer 595

effects are not observed immediately, and pioglitazone can be given as an add-on therapy

Answer 596

weight gain | fluid retention due to enhancement of amiloride-sensitive Na+ reabsorption.

Answer 597

α-glucosidase inhibitors, e.g. acarbose, slow the breakdown of starch/disaccharides into glucose in the GI tract and reduce the amount of glucose entering the bloodstream, as such they also aid weight loss

Answer 598

Given in combination with other treatments, side effects include flatulence and diarrhoea

Answer 599

the concentration of glycated haemoglobin (HbA1c), i.e. the level of covalent bonding of glucose with haemoglobin, the poorer the control of blood glucose and thus the more persistent hyperglycaemia is results in higher HbA1c values

Answer 600

(this is used when diet and exercise is insufficient) Stage 1 involves metformin alone, Stage 2 involves combining metformin with a second compound Stage 3 means adding a third compound or moving to insulin based treatment. A separate algorithm is used for those for whom metformin is contraindicated.

Answer 601

In animals, insulin is always the treatment of choice, regardless of Type 1 or Type 2 DM.