Pastest 3 Flashcards
Which envelope proteins on the surface of HIV virus enable it to get into cells?
GP120 binds to primary receptor (CD4 molecule)
GP41 mediates movement through the cell membrane
How long does it take for HIV to become AIDs?
5-10 years
How does mefloquine toxicity present?
Acute psychosis
What does bartonella henselae cause?
Cat scratch disease
Which serological marker most strongly confirms recent acute hepatitis B infection?
Anti-HBC IgM
HbsAg often disappears by the time patients are jaundiced, and is present in acute and chronic
What is Jo1 syndrome?
Polymyositis + interstitial lung disease
When is methotrexate used in SLE?
If arthritis is present
What are the causes of death in PAN?
Renal failure
Bowel obstruction or perforation
Cardiovascular causes
(does not affect the pulmonary arteries)
What are the features of thoracic outlet syndrome?
Disappearance of arm pulse when raised above head
Pain, numbness and tingling
What are the characteristics of scleroderma renal crisis?
Malignant hypertension
Rapid renal impairment
Onion skin intrarenal vasculature
More common in diffuse systemic sclerosis
How is bronchiolitis obliterans diagnosed?
Irreversible obstructive picture
CT: bronchial wall thickening and air trapping
What is the cause of hypoxia in primary pulmonary hypertension?
Intra-pulmonary shunting
Reduced diffusion capacity secondary to arterial fibromuscular dysplasia
How does sleep apnoea lead to cor pulmonale?
Chronic nocturnal hypoxia –> pulmonary artery vasoconstriction –> secondary pulmonary hypertension
What are the causes of primary pulmonary hypertension?
Plexogenic pulmonary arteriopathy
Chromosome 2
What type of arthritis can worsen in the post-operative period?
Crico-arytenoid arthritis
Causes stridor
What are the causes of type 2 membranoproliferative glomerulonephritis?
Partial lipodystrophy
Factor H deficiency
Measles
What can acute kidney rejection be confused for?
Post-transplant lymphoproliferative disorder
Polyomavirus BK virus
What are the two types of acute kidney transplant rejection?
Cell mediated
Antibody mediated
What are the criteria for diagnosis of antibody mediated acute kidney transplant rejection?
Graft dysfunction
Histological evidence of tissue injury
Positive staining for C4d
Presence of donor specific antibody
What medications are given during kidney transplant surgery?
1g methylprednisolone
Anti-CD25 monoclonal antibody e.g. basiliximab
Which antibodies are involved in acute kidney transplant rejection?
IgG
What is the WAGR triad?
Wilms’ tumour
Aniridia
Genitourinary problems
LD
What are the causes of normal anion gap metabolic acidosis?
CAT MUDPILES
Cyanide poisoning Aminoglycosides Toluene Methanol Uraemia DKA Paracetamol Isoniazid Lactic acid Ethanol Salicylates
Which type of nephropathy is caused by underlying malignancy in 10%?
Membranous
What are Bartter and Gitelman syndromes?
Bartter - kidneys cannot reabsorb chloride in the thick ascending limb of the Loop of Henle
Gitelman - kidneys cannot reabsorb chloride in the distal convoluted tubule
When are Bartter and Gitelman syndromes diagnosed?
Bartter - childhood
Gitelman - later
What is disequilibrium syndrome?
Cerebral oedema caused by rapid shifts of uraemic toxins, associated with too-rapid haemodialysis
What type of antibody deficiency is associated with infection with polysaccharide coated organisms?
IgG2
What investigation confirms hyperaldosteronism?
Saline suppression test
But often hypertension, hypokalaemia, and raised aldosterone are adequate for diagnosis.
When is oral aciclovir given in chickenpox?
Adults presenting within 72h onset
Pregnancy/immunocompromised
What are the features of Sweet’s syndrome?
Associated with myelodysplastic disorders
Plum coloured lesions, mucosal involvement
Neutrophilia and fever
How does lorazepam enhance the effects of anti-emetics?
GABA-A modulator
Increases the opening frequency of GABA activated chloride channels
What are the characteristics of disseminated mycobacterium avium complex?
Occurs in pts with CD4 <50
Fever + night sweats
Diarrhoea and weight loss
Hepatomegaly and lymphadenopathy
How effective is the BCG vaccine at preventing severe TB?
70-80%
What is the treatment of syphilis?
IM Procaine penicillin/benzathine penicillin
Pen allergic - azithromycin
When should you suspect alpha thalassaemia?
Microcytic anaemia
Normal/raised ferritin
How is methanol metabolised?
By alcohol dehydrogenase to formaldehyde
What are indications of haemodialysis in methanol poisoning?
Methanol concentration >50mg/dL Visual disturbance/CNS toxicity Severe metabolic acidosis Severe electrolyte imbalance Renal failure Deterioration despite initial treatment with fomepizole/ethanol
How does heparin cause hyperkalaemia?
Inhibits aldosterone secretion
leads to impaired renal potassium secretion
Particularly in patients who are diabetic or acidotic
What receptor increases response to chemotherapy if expressed on cancer cells?
P-glycoprotein
How does HCOM compare to aortic stenosis?
Similar symptoms and signs
Jerky pulse in HCOM
Valsalva increases intensity of murmur in HCOM and decreases murmur in aortic stenosis
Which cytotoxic agent is used in colorectal carcinoma?
5-fluoruracil
What is seen on fundoscopy in CMV retinitis?
Necrotising retinitis with haemorrhages
Brush fires
What is the treatment of hyphaema?
Acetazolamide to lower IOP (blood clots and blocks trabecular network)
Anterior chamber paracentesis 2nd line
What does asymmetrical diabetic retinopathy suggest?
Ocular ischaemic syndrome (on the side affected worse)
Why are nerve conduction studies normal in MS?
Peripheral nerves are unaffected
What are the ocular features of rosacea?
Blepharitis
Keratitis
Why are IV nitrates used in acute pulmonary oedema?
Activation of RAAS and high catecholamine levels lead to peripheral vasoconstriction which increases myocardial oxygen demand
What pressures are seen in right ventricular infarct?
High right atrial pressure
Low left atrial pressure
What is reversed splitting of the 2nd heart sound?
The pulmonary valve closes before the aortic valve
LBBB, HCOM, AS
What is a fixed splitting of the 2nd heart sound represent?
ASD or VSD
What is the choice of rhythm control in AF?
Structurally normal heart - flecainide
LVSD - amiodarone
IHD - sotalol
Which drugs can cause primary pulmonary hypertension?
Appetite suppressants - fenfluramine
Methamphetamine
Why is the posteromedial papillary muscle more likely to rupture than the anterolateral papillary muscle?
Supplied by right coronary artery only
Anterolateral is supplied by LAD and left circumflex
Where is the focus of radiofrequency ablation in AF?
Where the pulmonary veins join with the atrium
What is pro-insulin cleaved to?
Insulin and C peptide
What anaesthetic agents are patients most likely to be allergic to?
Neuromuscular blocking agents e.g. vecuronium
What is the cause of hyperglycaemia in trauma?
Noradrenaline and glucagon –> glycogenolysis
Cortisol acts more slowly –> gluconeogenesis
What is the cause of hoarse voice in recurrent laryngeal nerve injury?
Paralysis of the posterior cricoarythenoid muscle, which opens the vocal cords
What is the cause of Kartagener’s syndrome?
Absence of dynein - which converts chemical energy from ATP into ciliary movement
Why is renal disease not seen in Waldenstrom’s macroglobulinaemia?
Absence of light chains
In which population is Gaucher disease most prevalent in?
Ashkenazi Jews
Which complement changes are associated with acquired lipodystrophy?
Low C3
High C3b nephritic factor
Which cells produce CSF?
Ependymal cells
What are the two most common types of autoimmune encephalitis?
1) NMDA receptor abs –> presents with psychiatric sx
2) LGI1 receptor abs –> faciobrachio dystonic seizures
What are the features of progressive supranuclear palsy?
Symmetrical rigidity, proximal worse than distal Dysphagia Loss of verbal fluency Minimal autonomic dysfunction Vertical gaze palsy Early falls Poor response to levodopa
What is T wave discordance with LBBB?
The T wave deflection must be opposite the terminal deflection of the QRS complex
Concordant deflections suggest IHD/MI
Why are people with liver disease susceptible to hypoglycaemia?
Liver’s inability to produce glycogen
How are myeloproliferative disorders classified?
According to the proliferating type of cell
RBC: polycythaemia vera
WBC: CML
Platelets: essential thrombocytosis
Fibroblasts: myelofibrosis
What is melanosis coli pathognomic of?
Senna abuse
What are the signs of cardiac amyloid?
Dilated atria (restrictive filling pattern)
Thickened LV walls
Granular sparkling appearance of LV
Heart block
What is seen on MRI in variant and sporadic CJD?
Variant: increased signal in the pulvinar of the thalamus
Sporadic: increased signal in the caudate nucleus with cortical ribbon hyperdensity
What are the differences in presentations of variant and sporadic CJD?
Variant: 26 years, neuropsychiatric, painful sensory disturbance
Sporadic: 40-60 years, myoclonus, dementia, ataxia
What are the characteristics of inclusion body myositis?
Muscle weakness - esp quadriceps and finger flexors
CK can be normal
Aged over 50
What is the CSF biomarker for sporadic CJD?
14-3-3 protein
What is the cause of cavernous sinus thrombosis?
Suppurative process in the orbit, nasal sinuses, or upper half of face –> s.aureus
What are the features of cavernous sinus thrombosis?
Obstruction of ophthalmic vein: chemosis, oedema, cyanosis of upper face
Damage to 3rd, 4th, 6th CN: ophthalmoplegia
Damage to V1th CN: eye pain and hyperaesthesia of the forehead
What is myocardial bridging?
Coronary artery (commonly proximal portion of LAD) takes an intramuscular course - predisposes to IHD as compressed during systole
What are single nucleotide polymorphisms?
Point mutations (substitution of a single nucleotide) that result in changes in alleles
How does oestrogen form?
Cholesterol –> testosterone –> oestradiol (catalysed by aromatase)
Why can obese/alcoholic patients become feminised?
Alcohol and obesity increase aromatase activity
What is seen on bone biopsy in Paget’s disease?
Multinucleated osteoclasts
What does the RET protooncogene code for?
A receptor tyrosine kinase
How is an extra-adrenal phaeochromocytoma diagnosed?
Noradrenaline is particularly raised
MIBG scan - specific uptake in sites of sympathetic activity
What is the cause of nephrotic syndrome in SLE?
Class V nephritis - membranous nephropathy
Untreated UTI in diabetic patients can result in?
Renal papillary necrosis
Why can RV infarction cause hypovolaemic shock?
Blood pools in RV
Consequential decreased preload in LV
Why does proximal R coronary artery occlusion have a higher rate of complete heart block than distal?
Includes AV nodal artery and right superior descending artery
What type of axis deviation is seen in ASDs?
LAD: ostium primum
RAD: ostium secundum
What is the mode of action of adenosine?
G-protein coupled receptor agonist of the adenosine A1 receptor in AV node
What are the differences between cauda equina syndrome and conus medullaris syndrome?
C.E: gradual and unilateral, unilateral weakness, ankle and knee jerks affected, urinary retention
C.M: sudden and bilateral, symmetrical weakness distal>proximal, knee jerks preserved, urinary and faecal incontinence, fasciculations
Where does pre-mRNA splicing occur?
Nucleus
Why does quinine lead to hypoglycaemia?
Stimulates insulin release
What type of laxative is recommended to prevent/treat opioid induced constipation?
Stimulant e.g. senna
Why might a patient with allergies and coeliac disease have negative anti-endomyseal antibody?
IgA deficiency - they may have used IgA assay instead of IgG
Which cytokine drives the production of CRP?
IL-6
Which interleukin is seen in transplant rejection?
IL-2, as it causes T cell proliferation
Therefore use of calcineurin inhibitors such as tacrolimus and ciclosporin
Which antibody confirms recent infection?
IgM
As it is the first to be secreted in response to infection
What type of T helper cell drives autoimmune disease?
Th-17 - secretes IL-17
Which part of the antibody forms the antigen binding site?
The variable domains of each light and heavy chain of the antibody
How do you calculate ejection fraction?
(EDV - ESV) / EDV
Which antibody is negative in discoid lupus?
ANA
What is the treatment of cataracts?
Extracapsular lens extraction with a posterior chamber lens implant
What are the features of sarcoid granulomas?
Non caseating
Centre contains macrophages and Langerhans giant cells (which contain >10 nuclei)
Schumann body containing calcium phosphate crystals
Surrounded by ring of CD4 helper and then CD 8 suppressor cells
What is a crossover study?
The patient will receive all the drugs in the study
How does lambert Eaton syndrome differ from myasthenia graves?
- loss of reflexes
- autonomic symptoms
- ptosis, no oculoparesis
How does Terlipressin treat hepatorenal syndrome?
Decreased renin activity
