Exam 3 Concepts Flashcards
location of DNA replication
nucleus
location of DNA transcription
nucleus
location of DNA translation
cytoplasm
genes
information-containing elements in DNA
passed on to daughter cells when cell divides
deoxyribonucleic acid
DNA
store genetic information
of genes in human genes
25,000
3 billion base pairs
of chromosomes in human genes
23
22 autosomes
1 sex chromosome
(46/cell)
nucleotides
building blocks of all nucleic acids
3 components covalently bound together
3 components of nucleotides
sugar (ribose)
nitrogen-containing base
1-3 phosphate groups
bases of nucleotides
adenine - adenosine thymine - thymidine cytosine - cytidine guanine - guanosine uracil - uridine
adenosine
many fxns in dephosphorylated or phosphorylated forms
purines
adenine
guanine
pyrmidine
cytosine
thymine
uracil (RNA)
absence of oxygen atom at 2’ carbon in DNA
makes it highly stable
synthesis of DNA/RNA
phosphodiester bond formed between phosphate group on 5’ carbon of one nucleotide and hydroxyl group on 3’ carbon of next nucleotide
forms sugar-phosphate backbone
backbone of ladder
sugar-phosphate bonds
rungs of ladder
double stranded DNA held by hydrogen bond
2 bonds between A and T
3 bonds between G and C
complementary and antiparallel
double helix
one complete turn every 10 pairs
complementary and specific
organization of DNA
- nucleosomes
- chromatin
- euchromatin
- heterochromatin
nucleosomes
DNA packaged in nucleus associated with histones (basic proteins)
chromatin
DNA + histone complex
euchromatin
actively transcribed genes
heterochromatin
inactive segments
compaction of DNA
1 meter of DNA compacted into a micrometer - due to compaction into chromatin
DNA replication is semiconervative
each new DNA molecule has one parental strand and one new daughter strand identical strands - one acting as a template for the other
high fidelity of DNA synthesis
1 in 1 billion nucleotides (1 x 10^9)
DNA polymerase enzyme
first proofreading, before nucleotide is incorporated
self-correction by exonucleolytic proofreading - DNA polymerase III adds mismatched base, notices the mistake, and corrects it strand mismatch repair
efficient error correction
in 5’-3’ direction (3’ end does not serve well as template, which is why RNA error is more often)
critical to reduce mutations - associated with cancer
DNA replication
- DNA polymerase uses dNTPs as building blocks
- can only extend pre-existing strand replication
- initiated at ori (origin) site, multiple origins
- chromosome direction: 5’-3’
replication complex includes:
- DNA polymerases
- primase
- helicase
- SSB proteins
- topoisomerase
- ligase
DNA repair
- normal DNA
- DNA damage
- removal of damaged base
- DNA polymerase inserts new base using good strand as a template
- DNA ligase repairs nick
End Problem in DNA replication
newly synthesized lagging strand has a gap of about 1000 bases at its 5’ end (not enough space for replication complex to bind) with progressive cell divisions, this “gap” starts to eat into the chromosome, causing the cell to die
telomere
- complex of noncoding DNA and protein at ends of linear chromosomes
- maintain structural integrity of chromosomes
- solve ‘end problem’ of linear chromosomes
- several thousand tandem repeats of AGGGTT
- “mitotic clocks” whose length is inversely proportional to the number of times the cell has divided - cell division will cease when telomere becomes too short
- ex: PTSD can speed up this process
telomerase enzymes
reverse transcriptase maintains telomeric length
only present in germ cells, stem cells, cancer cells (immortality of cancer cells)
promoter
base-pair sequence that specifies where transcription begins
RNA coding sequence
base-pair sequence that includes coding information for polypeptide chain (protein - although not yet in final form) specified by gene
terminator
sequence that specifies end of the mRNA transcript
sequence of gene –> protein
- DNA
- pre-mRNA (exons and introns)
- mRNA (introns removed)
- polypeptide
DNA transcription
master blueprint encoded by DNA is expressed through RNA - working copies
mRNAs translated into proteins; other RNAs perform structural, regulatory, catalytic fxns
selectivity of DNA transcription
signals in DNA that instruct RNA polymerase when, how often to start, and when to stop
regulatory proteins involved in selectivity
introns
can code for several regulatory sequences
RNA
- sugar molecule = ribose
- uracil replaces thymine
- single-stranded
RNA transcription steps
- initiation
- elongation
- termination
RNA polymerase
- can initiate de novo synthesis
- lacks proofreading capability
- error rate = 1 X 10^4
- uses NTPs
- transcription initiated at promoter, stops at terminator sequence
- initiation requires transcription factors
promoter element of RNA
provides directionality to RNA polymerase and dictates which DNA strand is used as template
transcription factors
- proteins that regulate transcription bind promoter
- recruit RNA polymerase to promoter
- mediate response to signals
- modulate frequency of initiation
- respond to signals such as hormones, GFs, cytokines
- regulate temporal gene expression
- recruit co-activators such as HAT involved in chromatin remodeling
enhancer DNA sequences
bind enhancer-binding proteins (TFs) which greatly increase rate of transcription
types of RNA
- mRNA
- rRNA
- tRNA
mRNA
most genes in a cell transcribed to mRNA which direct synthesis of proteins
3-5% of RNA in cell
rRNA
form core of ribosomes
tRNA
adaptors in protein synthesis
RNA translation
process by which mRNA is used to direct synthesis of a protein - in cooperation with tRNA and ribosomes
mRNA may serve as template for thousands of proteins before it degrades
read linearly, from one end to another
each set of 3 nucleotides serve as codon for each particular amino acid
mRNA codons
do not direclty recognize amino acids; tRNA as translator is required anticodon at one end
amino acid attachment at other
tRNA structure
anticodon formed by 3-nucleotide sequence
recognition between mRNA codon and tRNA anticodon with complementary base pairing
why is DNA read 5’-3’
sequence is different - would code for different amino acid sequence/protein
ribosomes
- large complexes of proteins and RNA assembled in nucleolus
- find starting place on mRNA
- line up tRNA on mRNA
- set correct reading frame for codon triplets
- catalyze peptide bonds that hold together amino acids
- newly synthesized protein chain released from ribosome when it reaches stop codon
genetic code is a triplet code
- codon = 3 mRNA nucleotides
- 64 codons total
- 60 mRNA triplets for 19 amino acids, 3 for “stop”, 1 for methionine (start)
- most amino acids coded by more than one triplet, but each tripled linked to only one amino acid
AUG
methionine - start code
UAA, UAG, UGA
stop codons
phosphorylation
addition of a phosphate (PO4) group, necessary for activation/inactivation of protein
glycoslyation
addition of a sugar moiety, necessary for proper folding, fxn
hydroxylation
addition of hydroxyl (OH) group, affects folding of collagen
fatty acylation
addition of fatty acid groups (palmitoyl, myrisyl), crucial for membrane localization of protein
chaperones
aide protein folding to achieve functional form
primary protein structure
coded by gene
linear amino acid sequence held together by peptide bonds
secondary protein structure
held together by H-bonds between peptide groups
a-helix and B-pleated sheet
tertiary protein structure
interactions between amino acid side chains; ionic bonds; H-bonds; hydrophobic attraction forces; disulfide bonds
dictates fxn of protein
quaternary protein structure
3D structure of multi-subunit protein
transcription to final protein - summary
allele
variant of gene sequence
heterozygous
different alleles at a given locus
homozygous
same allele at given locus
locus
place where particular gene is located on chromosome
phenotype
observable properties; physical manifestations
genotype
genetic makeup with reference to particular trait
dominant allele
allele that is phenotypically expressed when homozygous or heterozygous
recessive allele
allele that is phenotypically expressed only when homozygous
penetrance
how many people carrying the disease allele actually have the disease (population-based characteristic)
expressivity
degree to which a genotype is expressed phenotypically in individuals - severity of disease
mutation
- change in DNA sequence at particular locus
- frequency >1% in population
- low frequency due to efficient DNA repair mechanisms
- single-stranded breaks: easily repaired
- double-stranded breaks: possible permanent loss of genetic information at break point
potential mutagens
- radiation
- chemicals
- viruses
point mutation
single base pair substitution
may cause affected codon to signify abnormal amino acid
frameshift mutation
addition/removal of one or more bases - changes “reading frame”
alters primary structure of protein
missense point mutation
wrong amino acid is made i.e. sickle-cell anemia (Val for Glu)
nonsense point mutation
stop codon inserted
silent mutation
same amino acid is made
duplication mutation
a few bases or chunks of chromosomes duplicated causes inactivation or over-activation of genes
deletion mutation
a few base or chunks of chromosome deleted
inversion mutation
chunks of chromosome inverted
translocation mutation
pieces of chromosomes exchanged between non-homologous chromosomes
Mendelian Single-Gene disorders
- alterations/mutations of single genes affected genes code for abnormal enzymes, structural/regulatory proteins,
- regulatory RNA classification: location: autosomal or sex
- mode of transmission: dominant or recessive
autosomal dominant disorders
- mutation of specific autosomal gene
- 1 mutant allele sufficient for disease phenotype
- males/females equally affected
- usually 1 affected parent
- unaffected individuals do not transmit disease
- offspring of 1 affected parent: 1 in 2 chance
- offspring of 2 affected parents: 3 in 4
- penetrance and expressivity vary in individuals
autosomal recessive disorders
- mutation of recessive autosomal gene
- males/females equally affected
- usually not apparent in parents; both parents are carriers
- unaffected individuals may transmit to offspring
- two carriers have 1/4 chance of having affected offspring and 2/4 chance of having carrier offspring
sex-linked (x-linked) disorders
- mutation of sex chromosome (almost always X)
- nearly all recessive
- females express when they have BOTH (rare)
- males always express (only one X)
- affected fathers transmit defective gene to all daughters, but not to sons
- carrier female has 1/2 chance of producing affected son or carrier daughter
- females affected: homozygous from carrier/affected mother and affected father ex: hemophilia A
polygenic and multifactorial disorders
- run in families
- more common than single gene disorders
- interaction of several genes: polygenic
- range of severity
- difficult to predict based on family history
- interaction of several genes and environment: multifactorial
tumor or neoplasm
“new growth” - abnormal mass of tissue benign or malignant (cancer)
cancer associated with
altered expression of cellular genes
benign vs. malignant tumor
malignant phenotype
- arises due to loss of control of cell number
- increase proliferation
- reduced death cells lose differentiated features and contribute poorly to tissue fxn
1/3 of cancer-related deaths due to
- tobacco use
- nutrition
- obesity
- sun exposure
- sexual exposure to HPV
tobacco use in cancer
two types of carcinogens: initiator (genetic damage) and promoter (tumor growth)
tobacco contains both
second-hand smoke
nutrition in cancer
dietary factors:
- fat
- alcohol
- fiber
- antioxidants
suggestions: -
- limit excessive calorie/alcohol intake
- increase dietary fiber, fruit, veggies
genetic mechanisms of cancer
mutations
acquired (somatic)
inherited (germline)
sporadic cancer inheritance pattern
occurs by chance, not inherited.
95% of all cancers
hereditary cancer inheritance pattern
- autosomal dominant cancer syndromes
- autosomal recessive
- familial cancers; uncertain inheritance
autosomal dominant cancer inheritance pattern
tumor suppressor (ts) genes
- single copy of inherited mutant gene increases cancer risk
- autosomal dominant pattern of inheritance
- children of mutation carriers have 50% risk of same mutation ex: retinoblastoma (Rb), Li-Fraumeni syndrome (p53)
cancer inheritance patterns
- carriers of mutant Rb or p53 gene almost always develop cancer
- clustering or rare, bilateral, multifocal cancers
- incomplete penetrance and variable expressivity
- associated w. specific mutation
autosomal recessive cancer inheritance pattern
- DNA repair genes
- genome instability
- high rate of certain cancers ex: xeroderma pigmentosum, blood syndrome, fanconi anemia
familial cancers of uncertain inheritance (inheritance pattern)
- early age of onset
- predisposition to cancer
- higher incidence of tumors in relatives
- not associated with specific mutation ex: breast, ovary, colon
checkpoint
control point in cell cycle where “stop” or “go ahead” signals regulate cell cycle
GI checkpoint
restriction point: proceed with cell cycle or shunt to G0 oncogenes, pRB: check for…
- cell size
- nutrients
- growth factors
- DNA damange
G0 checkpoint
resting state
G2 checkpoint
ok to enter mitosis oncogenes: check for…
- cell size
- DNA replication
M checkpoint
spindle assembly checkpoint
check for: chromosome attachment to spindle
S checkpoint
DNA synthesis - p53
do or die
mutational events in cancer
- subtle (point) or large (karyotypic) changes
- epigenetic modifications
- environmental agents, viruses, radiation
point mutations in cancer
- small insertions/deletions can convert proto-oncogene to oncogene or inactivate a ts gene
- in EGFR or RAS proto-oncogene: over-activates protein (gain of fxn)
- in Rb or p53 (ts’s) reduces/abolishes fxn (loss of fxn)
large karyotypic changes in cancer
- translocations: exchange parts of nonhomologous chromosomes causing: overexpression of proto-oncogene, creation of novel fusion protein
- deletions: whole or portions of chromosome lost - loss of ts genes
- gene amplifications: several hundred copies of gene on chromosome - overexpression of normal proto-oncogene
epigenetic modifications in cancer
heritable, reversible changes in gene expression w.o mutation
due to changes in DNA methylation and chromatin organization
low DNA methylation - high expression euchromatin
highly expressed affected by nutrition, environmental factors
genes that drive cancer
proto-oncogenes
tumor suppressor genes
for cancer to occur: suppress tumor suppressor genes (ts) and turn on oncogenes
proto-oncogenes
- accelerate cell growth and division
- transformed into oncogenes by gain of fxn mutations
may be:
- growth factors
- growth factor receptors
- cytoplasmic signaling molecules
- nuclear txn factors
- proteins in cell-cell or cell-matrix interactions
tumor suppressor (ts) genes
- inhibit cell growth and division contributes to cancer when inactive
- both copies inactivated when cancer develops
- one can inherit defective copy (much higher risk for developing cancer)
- Rb and p53 are important ts genes (others - DNA repair genes: BRCA1 and 2; apoptosis genes)
from proto-oncogene to oncogene
- oncogenes introduced to host cell by virus proto-oncogene mutation to oncogene (point)
- normal proto-oncogene over-active (translocation)
- extra copies of proto-oncogene in genome (amplification)
Rb gene
normally “master brake” for cell cycle blocks/stops cell division:
- binds trxn factors
- inhibits factors from transcribing genes that initiate cell cycle inactivating mutation of Rb gene
- removes restraint on cell division and replication occurs
- retinoblastoma, osteosarcoma, lung cancers
p53
- guardian of genome
- most common ts gene defect identified in cancer cells
- >50% human tumors lack fxnal p53
- transcriptional factor for cell cycle and DNA repair genes cellular stress monitor
- accumulates after stress
- binds to damaged DNA and stalls division to allow DNA repair
- may direct cell to apoptosis
how does HPV cause cervical cancer?
E6 and E7 viral proteins inactive Rb and p53
- E7: binds to Rb so promoter is turned on and cell divides
- E6: binds to p53, which degrades
BRCA1 and BRCA2 genes in cancer
tumor suppressor genes hereditary breast/ovarian cancer
HBOC syndrome family history and inherited defect in BRCA increases risk of breast cancer
- mutations in the different genes can cause same disease
six hallmarks of cancer
- self-sufficiency in growth signals
- resist anti-growth signals
- tissue invasion and metastasis
- limitless replication potential
- sustained angiogenesis
- evading apoptosis
self sufficiency in growth signals in cancer
- keep dividing
- oncogenes mutation at any step in growth signaling pathway
- growth factor
- GF receptor
- downstream signaling molecules
- trxn factors
resisting growth inhibitory signals in cancer
don’t stop growing
inactivation of ts genes (p53 and/or Rb)
cell cycle checkpoints non-fxnal
resisting apoptosis in cancer
don’t die
balance of pro- and anti-apoptotic proteins perturbed
tumor more from reduced cell death than from increased proliferation
cell immortality in cancer
keep going
up-regulation of telomerase enzyme in 90% of tumors
sustaining blood flow in cancer
feeding the tumor
stimulate factors that promote growth of blood vessels
tissue invasion and metastasis in cancer
take over
several steps
- process by which cancer cells escape tissue of origin and initiate new colonies of cancer in distance sites
metastasis steps
- carried by blood or lymph
- invade surrounding tissue
- enter blood/lymph vessel
- carried to distant site
- escape lymph/blood vessel to surrounding tissue
- establish tumor
mechanisms of metastasis
- loosening of intercellular jxns
- degradation
- attachment
- migration
emerging hallmarks of cancer
- altered energy metabolism
- avoidance of immune detection
- inflammation
- genome instability
multistep nature of carcinogenesis
initiation
promotion
progression
initiation of carcinogenesis
initiating events:
- genetic mutations (proto-oncogenes, ts genes)
- proliferation: cancer development each cancer has own combo of mutations that lead to malignancy
complete carcinogesn
can initiate cell damage
can promote cellular proliferation
partial carcinogens
promoters that stimulate growth
incapable of causing genetic mutations
sufficient to singly initiate cancer
promotion of carcinogenesis
stage during which mutant cell proliferates:
- activate another oncogene
- inactive ts gene
- nutritional factors
- infection regulated by many hormonal growth factors (may act as promoters for cancers)
- estrogen
- testosterone cancer cells produce telomerase
- immortality
progression in carcinogenesis
mutant, proliferating cells exhibit malignant behavior
change in structure, cell-cell attachment
secrete lytic enzymes evolved tumor cells differ from normal tissue significantly
angiogenesis
process by which cancer tumor forms new blood vessels in order to grow
late stages of development
-triggers not well understood
inhibition of angiogenesis is an important therapeutic goal
cancer therapy
early detection = best prognosis
mainstays of cancer therapies
surgery
radiation
drug/chemo
emerging cancer therapies
immunotherapy targeted molecular therapies
stem cell transplantation
sensory-discriminatory component of pain
how patient describes and experiences the pain
motivational-affective component of pain
the psychology, mood of pain
depressive aspect of it, having had pain before
cognitive-evaluative component of pain
what the pain means - good vs. bad pain (sore muscles vs. lung cancer)
pain and depression
which came first? worsen each other - tightly linked impact pain and quality of life
classifying pain
temporal
- –acute
- –chronic
etiology
- –cancer
- –non-malignant
pathophysiological
- –nociceptive (visceral + somatic)
- –neuropathic (peripheral + central)
acute pain
patient appears in distress
temporally related to noxious stimuli
signs: increased BP, HR diaphoresis mydriasis pallor
chronic pain
patient may not appear uncomfortable
pain extending beyond expected time course of syndrome
no obvious signs
care providers don’t want to give pain because patients don’t look like they’re in pain (adjustments)
somatic pain
nociceptive originates from receptors in skin, bones, muscles, joints, blood vessels ull, aching, etc. and can point to where it hurts
visceral pain
nociceptive when internal organs swell or become damaged within body
deep, gnawing, cramping and poorly localized
nociceptive pain
- process by which information about tissue damage is conveyed to CNS
- direct stimulation of afferent nerves due to tissue injury or tumor infiltration of skin, soft tissue,
- visceral pain is proportionate to stimulation of nociceptor
- emotional component is anxiety or depression, the other sensory input, and the nociception itself
nociceptive process
- peripheral tissues = transduction
- transmission to spinal cord to brain
- brain perception
- descending modulation to spinal cord
pain transduction
- nociceptor activation and sensitization
- -nociceptors are free endings of primary afferent nerve fibers distributed throughout periphery
- -noxious stimuli –> tissue damage -tissue damage –> chemical mediators
- -action potential
noxious stimuli
mechanical - touch/pressure
thermal - heat/cold
chemical - internal (help action potential generate) or external (ex: capsaicin)
chemical mediators of tissue damage
bradykinin, K+, histamine, serotonin trigger release of prostaglandins, norepi, epi, and substance P
fibers in pain transmission
A-alpha and A-beta fibers –> A-delta fibers –> C fibers
A-alpha and A-beta fibers
fibers that we need in order to feel ‘
- myelinated
- large
- proprioception, light touch
- no thermal threshold
A-delta fibers
transmit the first (ouch) pain
- sharp, well-localized pain
- mostly mechanical and thermal stimuli
- myelinated
- large diameter
- rapidly conducting
C fibers
the “reminder” pain
- second pain (if it continues = chronic)
- dull, aching, poorly localized pain
- sensitive to mechanical, thermal, chemical stimuli
- unmyelinated
- small
- slow
pain transmission
fibers terminate in dorsal horn of spinal cord
release nt (Ca++ mediated) that bind NMDA receptors
signal terminates in thalamus (relay station to cortical regions)
potential sites of pain modulation during transmission
- -sodium to modulation action potential
- -calcium-induced release of nt across synapse
- -receptors for nt released by calcium
pain perception
impulse becomes conscious experience of pain
structures involved in pain perception
- reticular system - autonomic response
- somatosensory cortex - localization and characterization
- limbic system - emotional and behavioral (harder to target with drugs - behavioral therapy)
behavioral therapy for pain perception
distraction, relaxation, imagery
if patient believes it will work, it will work
pain modulation
changing/inhibiting pain impulses
“rub it, it will feel better!”
key players in pain modulation
- endogenous opioids,
- serotonin (5HT),
- norepi (NE),
- GABA
- inhibit transmission of noxious stimuli
rubbing a painful spot
activates non-nociceptive neurons which inhibit transmission of nociceptive info (A-beta fibers)
endogenous opioids in pain modulation
block release of nts such as substance P
NE and serotonin in pain modulation
increased by antidepressants to inhibit noxious stimuli
GABA in pain modulation
increased by baclofen to reduce pain due to spasticity
nociceptive process summary
transduction: noxious stimuli converted to impulses
transmission: movement of impulses up spine to brain
perception: recognizing, defining and responding to pain
modulation: descending pathways exert inhibition on pain transmission
achieving zero pain
not always possible because we try to modulate natural pathways with drugs, which have adverse side effects
inflammatory pain
adaptive mechanism that facilities healing of injured tissue (to avoid re-injury)
- can be too much
- abates and resolve with healing
- increases sensitivity to stimuli in affected area
- attributed to peripheral sensitization and central sensitization
analgesia
reduced perception of pain stimuli
anesthesia
reduced perception of all sensation
paresthesia
abnormal sensation; not unpleasant
dysesthesia
abnormal sensation; not pleasant
allodynia
severe pain response to normally non-painful stimuli
hyperalgesia
extreme response to painful stimuli
secondary hyperalgesia
spread of sensitivity to noninjured areas
peripheral sensitization
lower threshold for activation and increased rate of firing role in allodynia, hyperalgesia, central sensitization
chemical mediators saturate site of injury
central sensitization
- increased excitability of neurons w/in CNS
- ongoing nociceptive input from periphery causes gradual increase in dorsal horn neuron firing (wind up)
- prolongation of input results in longer-lasting dorsal horn excitability
- causes changes in nerves that cause chronic pain
“wind-up”
- increase in NMDA receptors in dorsal horn that have an enhanced responsiveness to glutamate that causes impulses long after stimulus has ceased
- NMDA receptors switch from low pain to high pain and perpetuates pain state
- late phase is due to gene expression changes via activation of txn factors - long-lasting changes in dorsal horn neuronal fxn
manifestations of central sensitization
- hyperalgesia
- allodynia
- persistent pain (after stimulus ceases)
- referred pain can persist
- have injury heals in chronic pain states
neuropathic pain
- maladaptive
- originates from direct neuronal injury resulting in disturbance of fxn or pathologic change
- peripheral vs. central (where lesion occurs)
- description: burning, stinging, numb, tingling, electric
mechanisms of neuropathic pain
- central sensitization
- ectopic excitability
- structural reorganization
ectopic excitability in neuropathic pain
- nerve regeneration results in sprouts and neuromas that fire spontaneously
- peaks several weeks after injury
- changes in Na/K channel expression
structural reorganization in neuropathic pain
low-threshold sensory fibers terminate in areas where nociceptive neurons usually terminate - good things can feel like pain
allodynia and hyperalgesia
examples of neuropathic pain
central: poststroke pain, MS, Parkinson’s, spinal cord injury (damage to CNS)
peripheral: postherpetic neuralgia, diabetic neuropathy, chemotherapy-induced neuropathy, HIV sensory neuropathy, phantom limb pain treated the same way
consequences of pain
- physiological
- quality of life
- financial
physiological consequences of pain
- acute pain that is not controlled
- is more likely to become chronic than acute pain that is controlled
- undertreated pain early in life is associated with pain later in life
pain as 5th vital sign
led to a lot of opioid prescriptions - reeling it back while still treating it appropriately now
nonpharmacologic treatment of pain
- physical therapy
- cognitive behavior therapy
- stimulation therapy (TENS units)
- cold/heat application
pharmacologic treatment of pain
analgesics
adjuvants
analgesic ladder
pain persisting or increasing –> pain persisting or increasing –> relief from pain
step 1 in analgesic ladder
non-opioid
+/- adjuvant
step 2 in analgesic ladder
opioid for mild/moderate pain
+/- non opioid
+/- adjuvant
step 3 in analgesic ladder
opioid for moderate/severe pain
+/- non-opioid
+/- adjuvant
Stage I symptoms of acetaminophen overdose
(12-14 hrs)
- A/N/V
- diaphoresis
- pallor
Stage II symptoms of acetaminophen overdose
(24-72 hrs)
- RUQ abdominal pain
- AST, ALT, lactate, phosphate,
- bilirubin and PT/INR elevated
Stage III symptoms of acetaminophen overdose
(72-96 hrs)
- A/N
- malaise
- abdominal pain
- confusion
- liver failure
- coagulation effects
- encephalopathy
- hypoglycemia
- renal failure
- cardiomyopathy
- mortality w/o antidote: 3-4%
opiates and opioids
- from Greek word juice (opos)
- 20 different naturally occurring alkaloids
- opiates = naturally occurring products and semi-synthetic derivatives
- opioids = all compounds related to opium
MOA of opioids
decrease calcium presynaptically and increase K postsynaptically to slow/inhibit action potential
Mu
in pain modulating regions of CNS
analgesia, euphoria, respiratory depression, miosis, reduce GI motility
Kappa
in deep layers of cerebral cortex spinal
analgesia, sedation, miosis, respiratory depression, psychotomimetic and dysphoric effects
Delta
in limbic regions of CNS spinal/paraspinal
analgesia, dysphoria, hallucinations, respiratory stimulation
response to opioids
1st: analgesia
2nd: sedation
3: resp. depression
tolerance
needing higher doses to elicit same response
dependence
physiologic receptor response to exogenous substance and result from removing that substance
addiction
any recurrent activity which results in negative consequences despite known consequence (includes social consequences)
opioid induced hyperalgesia
increased pain despite increasing doses of opioids -confused with tolerance
theories of opioid induced hyperalgesia
- -toxicity of 3-position glucuronides (i.e. morphine)
- -NMDA agonism
- -increased spinal endogenous activity
- -others
antidepressants
block reuptake of nt, causing constant presence of nt
ex: serotonin, NE
interventional anesthetics
epidural/spinal analgesia
nerve blocks
regional: anesthetize extremity but not entire leg
capsaicin
- depolarize nociceptors and release of substance P
- decrease subs. P, decrease pain perception
- decreased burning pain with regular use
- must use 4x daily
- always wash hands after
drugs used in modulating central processing pathway
- anticonvulsants
- NMDA receptor antagonists
- local anesthetics
- antidepressants
- opioids
drugs used in modulating descending pathway
antidepressants
opioids
drugs used in modulating ascending pathway
anticonvulsants
topicals NSAIDs
most common infection sites
respiratory tract
urinary tract
pneumonia
infection of lung tissue, from alveoli to interstitium with inflammation and impaired gas exchange
UTI
microorganisms present in urinary tract not accounted for by contamination from vagina asymptomatic bacteriuria –> systemic infection complicated vs. uncomplicated
pathogen
disease-causing microorganism
infection
local shift in favor of pathogen over host with pathological consequences due to toxin production and invasion with subsequent inflammation
endotoxins produced by…
gram negative
exotoxins produced by…
gram positive
virulence
strength of microorganisms’s pathogenicity factors include: adhesins and protective capsules
adhesins
molecules that mediate adherence to cell surface
inoculum
quanitity of microorganisms
risk for infection
(inoculum x virulence)
host resistance
atypical bacteria
won’t stain because their cell wall is thick, waxy, and hard
gram positive stain
violet
gram negative stain
pink
infection: chain of transmission
- reservoir
- portal of exit
- mode of transmission
- portal of entry
- susceptible victim
possible reservoirs in chain of transmission
human
animal
insect
soil
possible portals of exit in chain of transmission
nasal mucosa
oral mucosa
possible modes of transmission
insect bite
nasal droplets
semen
possible portals of entry in chain of transmission
nasal mucosa
oral mucosa
skin abrasion
skin puncture
possible susceptible victims in chain of transmission
malnourished
unimmunized
immune compromised
incubation
time between exposure and symptoms
prodrome
non-specific symptoms often a feeling of malaise, may have headache, fatigue, other non-specific symptoms
illness
over S/Sx of infection
recovery
return toward homeostasis
chronic carrier state
possible in some infections
CAP
community acquired pneumonia
HAP
hospital-acquired pneumonia: diagnosis made >48 hr after admission
VAP
ventilator-associated pneumonia: diagnosis made 48-72 hr after endotracheal intubation
HCAP
healthcare-associated pneumonia: diagnosis made
healthcare-associated pneumonia risk ractors
- -hospitalized in acute care hospital >48 hr within 90d of diagnosis
- -resided in nursing home/long-term care facility
- -received recent IV antibiotic therapy, chemo, wound care w.in 30 days before diagnosis
- -attended hospital/hemodialysis clinic
VRSA
vancomycin-resistant staphylococcus aureus
MDR
multi-drug resistant
risk factors for pneumonia
- 65 yo
- smoker
- lung disease
- chronic disease (DM)
- hospitalization
- immobility
- depressed cough reflex
- dysphagia
- immunocompromised
- flu
- alcoholism
- IV drug abusers
- malnourishment
- inhalation of chemicals
mucociliary escalator
respiratory tract defense mechanisms
80% cells lining central airways are ciliated, pseudostratified, columnar
each has 200 cilia that beat 1000x/min
any bacteria/particle > 5um trapped in mucus and exit via mucociliary escalator up the throat and eliminated via cough reflex or swallowed (acid)
alveolar macrophages
always present and can phagocytose bacterial invaders 5 um that make it into the lungs
release inflammatory cytokines to recruit other cells of inflammation
complement, IgA, IgG, T cells play roles
virulence of S. pneumoniae
- external polysaccharide capsule to avoid phagocytosis
- secretes protein to adhere to mucosa in upper airways
- secretes protein to destroy ciliated cells
- secretes protease to inhibit IgA (which normally binds bacteria to mucus to facilitate clearance)
bacteria make it to the lungs via
inhalation (most common)
aspiration
hematogenous (bloodstream, least common)
inflammatory response r/t pneumonia
started by alveolar macrophages
- Il-6 and TNF-a initiate fever
- -other cytokines attract neutrophils which kill bacteria via ROS, enzymes, antimicrobial proteins (cause damage to lung tissue)
- -neutrophils extrude meshwork with antimicrobial proteins to trap and kill bacteria (neutrophil extracellular traps - NETS)
- -inflammatory mediators released/recruited by macrophages create alveolar capillary leak
- -alveolar spaces fill with exudative fluid and debris
S/Sx of pneumonia
- fever chills
- dyspnea
- productive cough
- pleuritic chest pain
physical exam results of pneumonia
tachypnea, tachycardia, dullness to percussion, diminished breath sounds, inspiratory crackles, tactile femitus, egophony
other clinical manifestations of pneumonia
- infiltrate on CXR
- proper specimen, gram stain, culture &
- susceptibility
- leukocytosis with PMNs predominating,
- low O2 sat
PMN
polymorphonuclear cells, aka granulocytes, of which neutrophils are most dominant type
extra-pulmonary clinical manifestations of pneumonia
- bradycardia
- abdominal pain
- myalgias
- others
- most common in atypical pathogens
CURB-65 criteria
determines inpatient or outpatient treatment 1
pt each for:
C - Confusion
U - Uremia; BUN > 20
R - Respiratory rate > 30 B - low BP; SBP
65 yo
CURB-65 scoring
0 = low, outpatient
1 = low, outpatient
2 = moderate, outpatient (supervised) or inpatient (short)
3 = mod-high, inpatient
4/5 = high, inpatient (ICU)
cystitis
lower UTI infection of bladder and/or urethra
pyelonephritis
upper UTI infection
above bladder; kidneys, ureters, peri-renal tissue
may result from bladder bacteria ascending into ureters and kidneys
complicated UTI
(upper or lower): associated with underlying condition that increases risk of therapy failure
underlying conditions of complicated UTI
- diabetes
- pregnancy
- S/Sx > 7 days w/o care
- hospital acquired infection
- renal failure
- urinary tract obstruction
- indwelling catheter, etc.
- recent urinary tract instrumentation
- fxnal/anatomic abnormality of UT
- UTI history in childhood
- renal transplantation
- immunosuppression
uncomplicated UTI
upper or lower healthy nonpregnant adults w/ no risk factors for treatment failure
risk factors for UTI
- structural abnormality in UT (VUR and BPH)
- urinary stasis
- female anatomy (#1 risk factor)
- improper hygiene
- postmenopausal
- prior UTI
- recent sexual activity
- spermicides, diaphragms
- DM, CKD
- catheterization/indwelling catheters
- pregnancy
- other instrumentation in UT
VUR
vesicoureteral reflux
condition where urine reflexes back upwards
BPH
benign prostatic hyperplasia
normal defense mechanisms of urinary tract
-urine flushes out bacteria before they can adhere to bladder wall -low pH of urine; intolerable to most bacteria -proteins secreted by kidney prevent bacterial adherence -vaginal lactobacilli kill uropathogens -mucopolysaccharide lining of urethra/bladder inhibits penetration and adherence of bacteria -prostatic secretions are bactericidal -secretory IgA -infalmmatory response
why is E. coli such a common cause of UTI?
-large quantities in gut; proximity to vagina and urethra -flagellae permit mobility -virulence factors -surface adhesions that mediate binding to receptors on uroepithelial cells in urethra/bladder -fimbriae permit adherence fo uroepithelial cells and block phagocytosis -polysaccharide capsule -hemolysin induces formation of pores in cell membrane of epithelial cells, RBCs, immune cells -iron transport system to uptake iron in iron-poor environments
pathophysiology of UTI
urinary tract usually sterile -bacteria establish infection in most UTIs via ascension from urethra to bladder (colonization of vaginal introitus and periurethral area with gut microorganisms) hematogenous spread more rare, usually to kidneys bacteria adhere to urethra/bladder epithelium and invade/multiply - form biofilm toxins secreted by bacteria damage epithelium - exfoliation of epithelium inflammatory response continuing ascent is pathway for pyelonephritis
clinical manifestations of lower UTI
- dysuria
- urgency
- frequency
- nocturia
- suprabuic heaviness/pain
- gross hematuria
- bacteriuria, pyuria
- nitrite (+), leukocyte esterase (+)
clinical manifestations of upper UTI
- fever, chills
- flank pain
- N/V
- malaise
- costovertebral tenderness (CVA)
- bacteriuria, pyuria nitrite (+), leukocyte esterase (+)
- antibody-coated bacteria
clinical manifestations of pneumonia and UTI in geriatric patients
may not present with classic symptoms (may not be febrile) common cluster of symptoms in both is “change in mental status”:
- -confusion
- -delirium (may be misdiagnosed as or superimposed on dementia)
- -lethargy
- -sudden incontinence (esp. in UTI)
bacteremia
bacteria in bloodstream
SIRS definition
systemic inflammatory response syndrome
infectious or non-infectious
sepsis
SIRS due to infectious causes
severe sepsis
sepsis with 1+ organ dysfxns, hypoperfusion, or hypotension
septic shock
sepsis w/ persistent hypotension despite fluid resuscitation, along w. perfusion abnormalities
SIRS symptoms
2+ of:
- -core temp >38.3C or 90bpm -RR>20 or PaCO2 12,000 or 10%
- -cardiac index > 3.5 L/ min*m^2
- -plasma CRP or procalcitonin > 2 std dev above normal
- -altered mental status
- -arterial hypoxemia, hyperlactatemia, decreased cap refill, coagulation abnormalities
- -acute oliguria, increased creatinine, positive fluid balance
- -thrombocytopenia
- -ileus, hyperbilirubinemia
- -hyperglycemia
prophylactic therapy for infection
preventative requires knowledge of the most likely pathogens -
for individuals at risk for infection make best choice of antimicrobial that will reduce pathogen at potential site of infection
empiric therapy for infection
what the bacteria is likely to be make best choice of antimicrobial that will help eradicate the pathogen at site of infection;
take host factors into account
definitive therapy
data on pathogen(s) and susceptibility pattern(s) to antimicrobials is already known
narrow (de-escalate) from initial empircal therapy
disk-diffusion
qualitative method to measure pathogen susceptibility
disk infused w. antibiotic is placed on agar plate
minimum inhibitory concentration (MIC)
drug concentration at which organism’s growth is inhibited
minimum bactericidal concentration (MBC)
drug concentration at which organism death occurs
susceptibility determined by
MIC values (+)
clinically achievable drug concentrations at site of infection
ideal antimicrobial propeties
- selective toxicity
- easily classified
- no acquired resistance
selective toxicity
gets the bug and not the host
gets the right bug with no collateral damage to microbiota of gut, GU tract, etc.
antimicrobials: easily classified based on
- organism
- susceptibility
- mechanism of action
no acquired resistance
keep organism susceptibility from evolving
organism susceptibility changes over time
superinfection
a new infection that appears during treatment of a primary infection
develops when antibiotics kill microbiota that normally inhibit pathogenic
bacteria more likely to occur with broad spectrum Abx
C. difficile superinfection - etiology
G+, spore-forming, anaerobic bacillus that infects bowel injury to bowel
caused by release of toxins - causes intense, frequent diarrhea (dehydration and electrolyte imbalance)
C. difficile superinfection - development
almost always preceded by antibiotic use
- -spore ingested or may already be present, but under control
- spores transferred to patient via hands of healthcare workers
- -spores remain viable in environment for weeks
- -once ingested, spores enter vegetative state and reproduce
- -spores can go thru stomach acid
C. difficile superinfection - elimination
offending antibiotic stopped and other antibiotic started to kill C. diff can be difficult to eradicate and can recur
contraindicated with drugs that slow bowel motility - increased toxicity from C. diff toxins
resistance to antibiotics
biggest current challenge to effective treatment of infectious diseases
natural resistance
organism has an inherent train that makes it resistant to the drug
ex:
- -absent drug target molecule or process
- -altered cell surface permeability to drug
acquired resistance
ex:
- -enzymes that modify/inactivate drug
- -altered ability to accumulate drug (efflux)
- -modified site of action for drug
- -altered cell surface permeability to drug
how does acquired resistance occur?
spontaneous mutations
- rapid growth rate and large number of cells
- -resistance genes transferred directly to all bacteria’s progeny during DNA replication
- cell-cell contact: direct transfer of plasmids taken up from external environment after death/lysis of another bacterium
- bacteria-specific viruses (bacteriophages) that transfer DNA between two closely related bacteria
beta-lactam ring
integral part of many antibiotics susceptible to B-lactamase, which cleaves ring and renders drug inactive
resistance bacteria produce variety of B-lactamases
generalized MOAs of antibacterial agents
- cell wall active
- interfere w/ protein synthesis
- interfere with nucleic acids
- anti-metabolite antibacterials
bacterial cell wall : gram+ vs. gram-
G+: thicker peptidoglycan layers, but simpler structure. penicillin easily penetrates
G-: thinner peptidoglycan layer but more complex walls. outer membrane with pores to restrict entry, plus lipopolysaccharide for integrity purposes and to protect membrane from chemical attack. only some penicillins can cross outer membrane both have penicillin-binding proteins (PBP)
PBP
penicillin-binding proteins
penicillin must bind to them to produce antibacterial effects
transpeptidase
penicillin-binding protein that normally creates crossbridges between strands of peptidoglycan polymers to give the cell wall added strength
by inhibiting them, penicillins prevent crossbridge formation and weaken cell wall
MRSA
- methicillin-resistant staphylococcus aureus
- acquired genes that code for PBPs with low affinity for penicillins and cephalosporins, so they cannot exert antibacterial effects
- resistant to all penicillins and cephalosporins
- initially only in healthcare environments; community MRSA now common
causes skin and soft tissue infections:
- -furuncles and carbuncles
- -necrotizing fasciitis
- -pneumonia
spreads via skin-skin contact
aminoglycoside MOA
bind to 30S ribosomal subunit and
1) block initiation
2) terminate synthesis early
3) cause misreading of genetic code
fluoroquinolone MOA
interrupt DNA replication and txn by inhibiting bacterial topoisomerase IV (DNA unwinding) and DNA gyrase (DNA supercoiling)
sulfonamide MOA
disrupt bacterial folic acid synthesis (necessary step in nucleotide synthesis)
bacteriostatic antibiotics
prevent bacterial growth
bactericidal antibiotics
kill bacteria outright
concentration-dependent antibiotics
as the concentration of the drug increases, the rate and extent of bacterial killing increases
time-dependent antibiotics
the duration of exposure to drug ABOVE THE MIC is key.
beyond a certain point, increasing concentration does not increase rate of bacterial killing
dosing a concentration-dependent antibiotic
once/day dosing has same effectiveness as 3x/day dosing but once/day means more of the 24hr period is under MIC and minimizes development of adverse rxns such as ototoxicity
dosing schemes
allow best chance for drug to get bug
combining antibiotics occasionally
- -prevent resistance
- -polymicrobial infection
- -synergy
penicillin allergy
most common cause of drug allergy
severity: minor rash to life-threatening anaphylaxis
GI upset is not an allergic rxn
differentiating cephalosporins
newer generations more active against G- bacteria and less susceptibility to B-lactamase enzyme
3rd and 4th only ones that can treat brain infections (CSF)
patient teaching to reduce development of antibiotic-resistant bacteria
- finish entire course
- do not borrow others’ antibiotics
- colds/URIs are viral, not bacterial
antibiotic side effects
any antibiotic can cause GI upset (N and V/noV)
many antibiotics can cause candidiasis
these are NOT allergic rxns
administering antibiotics
- many will be IV
- always check allergies
- always check infusion time - can cause rxn if too quick
- an allergy can develop at any time
- stop infusion FIRST if you observe an allergy, then proceed with additional interventions
