OMSI- CRS III

corynebacterium diphtheriae

causes diptheria

• gram positive rod with a club-like swelling at one end

• cluster in V, L, and Y shapes: “Chinese letter arrengement”

• can form pallosades where they line up length wise next to eachother

• have metachromatic (babes-earnst) granules that will stain distrinct to the gram stain

• non-motile and non-spore forming

• catalase positive

corynebacterium diphtheriae toxigenic strains

have the diphtheria toxin gene.

• gene is carried by a beta bacteriophage that can insert the gene through lysogenic conversion (aka transduction)

• will bind to heparin-binding epidermal growth factor on respiratory epithelia, heart, and nerve cells

• inhibits host protein synthesis by ADP ribosylation that inactivates EF-2

diphtheria epidemiology

worldwide, but rare in the US and other developed counteries

• human reservoir

• transmitted through droplets or skin-to-skin

• worse for those below 12 and elderly

diphtheria virulence factors

• pili/fibriae used for adhesion

• major factor is disptheria toxin (A-B exotoxin)

iron and DT

the iron dependent reprossor protein can regulate DT gene, so iron levels will determine host response

• low iron → inactive repressor → tox gene is also not repressed → more toxin production

• high iron → active repressor → tox gene is repressed → less toxin

DT pathogenesis

has an A and B subuinit. Note that the bacteria itself doesn’t enter blood but the toxin can

• B subunit binds to receptors on host cells. endocytosis is triggered

• in endosome, subunits will dissasociate from eachother

• A subunit (ADP ribosylating acativity) will inhibit EF-2

• host protein translation is inhibited

respieratory diphtheria clinical presenatation

• proliferate in pharynx epithilia cells. after 2-3 days symptoms develop

• flu-like symptoms, sore throat with exudative pharyngitis (white, firmly adhered membrane that can cause difficulty breathing)

• swollen neck

respiratory diphtheria complications

caused from toxin dissemination

• myocarditis- can cause congestive heart failure

• neurotoxicity

• renal failure

cutaneous diphtheria

from skin-skin contact

• opportunistic, a break in skin allows it in

• papule will progress to a chonic, non-healing ulcer. can be covered in gray-ish membrane

diphtheria diagonsis

• microscopy

• can culture on cysteine tellurite blood agar (colonies will look black) or tinsdale agar (black halo). loeffler medium will produce metachromatic granules

• Elek toxin test- antibody mediated, precepitation lines suggest toxin presence

• EIA (enzyme immunoassay) toxin test and PCR for toxin gene

diphtheria treatment

treat even when it’s only suspected

• antitoxin- only for circulating toxin and not cell bound

• antibiotics like penecillin. intramuscular if pt cannot swallow a pill

diphtheria vaccine

toxiod vaccine, uses an inactive form of the diptheria toxin

• DTap- infants andyoung children

• Tdap- booster

• DT/Td- when pertussis vaccine is not tolerated

listeria monocytogenes

• gram positive rod (coccobacilli), forms umbrella like growth in semisolid agar

• facultative anerobic

• non-spore forming

• can grow in refrigeration temps

• motile through tumbling

• CAMP test positive

listeria epidemiology

• in US, semi rare with 16% mortaility

• typically in outbreaks, 1-5% of carriers are asymptomatic and shed in feces

• transmitted through ingested food or from mom to child

• pregnant women, neonates, elderly, and immunocompromised at at highest risk

listeria pathogenesis

• contaminated food is ingested

• bacteria invade small intestine epithelia to through InIa/InIB binding E-cadherin. triggers endocytosis

• inside cell, will escape endosome through lysteriolysin O (LLO) and phospholipases (PIcA and PIcB) into cytoplasm.

• proliferation within host cells

• ActA protein triggers actin tails that can propell itself to another cell. can spread without exposure to immune system

• can infect macrophages and desaminate into organs

listeria clinical presenatation

• gastroenteritis: watery diarrhea, fever, nausea, pain. rapid onset

• invasive disease in pregnant and neonates, meningitis, encephalitis, and septicemia. This will start after 2 weeks since exposure

invasive listerosis

when lysteria escaped intestine, risk is 10x higher in pregnant women

• mild, flu like symptoms. Can cause miscarriage, still birth, neonatal infection

• in non-pregnant people, presents as bacteremia, meingitis/encephalitis, 5% fatality

neonatal listeriosis

invasive lysteria in neonates

• early onset- from mom, can cause abscesses and granulomas in many organs

• late onset- from delivery or environment, causes meningitis and miningoencephalitis

listeria lab diagnosis

• samples from blood, CSF, stool, amniotic fluid

• microscopy

• cultures grow in cold, some beta hemolysis on sheeps blood

• umbella-like growth in semifluid agar

• positive CAMP test when tested with staph aureus. enhanced hemolysis

• catalase postive

• esculin hydrolysis postive

T cells receptor

• an alpha and beta chain

• an apical variable region and below that is a constant region. then the transmembrane region and cytoplasmic tail

CD3

• composed of an epison, Delta, gamma and zeta subunit.

• will associate with TCR to help signal transduction once an antigen is recognized

TCR coreceptors

colocalized with TCR. have a immunogolbulin-like extracellular domain, transmembrane, and cytoplasmic domains

• CD4 (one chain)- interact with MHC II

• CD8 (heterodimer)- interacts with MHC I

TCR signaling

• TCR interacts with antigen on a APC

• depending on if it’s MHC I (Tc) or II (Th), CD4 or 8 helps to stabilize the complex

• within the cell, CD3 receptors recruit Lck to complex

• cell signaling cascade is propagated through zeta chain of CD3

T cell maturation

1. starts in bone marrow, NK/T precursor cell

2. migrated to thymus, T cells are in double negative stage where no CD8 or 4 is expressed. (stages DN1-4)

3. in DN2 and DN3, beta chain of TCR is rearranged

4. after DN3, the Pre-TCR checkpoint ensures signal transduction viability. if passes, will mature to DN4

5. DN4 matured into TCRb (double positive), which will undergo TCRa reaagenement and selection.

6. if it passes will become TCRab (double positive),

7. TCRab checkpoint ensures no reaction to self. if it passes, will become single positive CD4 or CD8

8. 4 SP phases while selection happens

double negative thymocyte committed lineage cell markers

• have lost stem cell markers (CD 34 and CD44)

• has CD2 and CD5 for adhesion and signaling

• IL-7 cytokines receptor, aids in early T cell dvelopment

• CD1A- an MCH I like-molecule

• TCR genes are starting to rearrange

Double positive thymocyte potential

winin the cortex of thymus: at this stage, can differentiate into:

• NK T cells

• single positive T cells (CD4 or 8)

gamma-delta T cells

differntiate from Double Negative 3 cells

• must happen before alpha gene reaggangement, because during rearrangement the genes for Delta chain are cleaved

single positive T cell selsection

through reaction with thymic epithelia, will express all protein types in body

• postive: weak recognition of self molecules, least common

• failure of positive selection (neglect): no recognition, most common

• Negative election: strong recognition of self , second most common

AIRE

Master transcription factor in thymic stromal cells, allows for expression of whole genome

APS1

autoimmune polyglandular syndrome 1: a disease caused by AIRE gene mutation

• more than 60 types, autosomal resessive

• will show antibodies against interferons

• chronic mucocutaneous candidias

• hypoparathyroidism

• adrenocortical insufficency

thymic output over time

thymus will regress with age

• less naive T cells

• more memory T cells

regulatory T cells

controls self tolerance and inflamatory responses

• Will have strong affinity to self, will stop Tc or Th from activating from self

• when they bind through antigen presenting, Treg will suppress T cells

myoglobin vs hemoglobin

• myo is a single chain, hemo is a homodimer

• myo is for oxygen storage, and hemo is oxygen transport

• myo has only charged amino acids on surface, hemoglobin has some non-polar amino acids

globin genes

will always be promoted by presence of heme

• early fetal: zeta (fetal alpha) and gamma (fetal beta)

• perinatal: alpha (chromosome 16) and gamma (fetal beta, also chromosome 11) chains

• adults: alpha (chromosome 16) and beta (chromosome 11) genes

switching is facilitatated by transcriptional modification

how does oxygen bind to hemoglobin

• Hb has a 5 coordinate Fe ring, 4 bonds to a nitrogen within heme and 1 to a histidine in globin

• oxygen binds to Fe2+, changes shape in hemoglobin which will affect the conformation of others. facilitates cooperative binding

• cooperative binding means as oxygen’s are stripped from heme, it becomes easier to let go, and vise versa. produces a sigmoidal curve

myoglobin oxygen binding

non-coperative binding

• simple hyperbolic affinity curve, when oxygen is limited during exercise myoglobin releases it

• a more left shifted curve is a higher oxygen affinity (saturation is achieved with a low concentration)

T and R states of hemoglobin

• Tense- more interactions and more ridged. lower O2 affinity, when heme is deoxygenated

• relaxed- less interactions, more flexable and higher O2 affinity. when heme is actively bound to oxygen.

O2 binding triggers a shift from tensed to relaxed

negative allosteric affectirs of hemoglobin-O2 binding

ment to enhance the efficiency to oxygen unloading through reducing affinity- a right shift on a binding curve

• protons

• CO2

• DPG (aka 2,3 BPG)

• high temperatures (such as through exercise)

bohr effect

pH affect on hemoglobin affinity

• lower pH is associated with more CO2 in blood, so a low pH decreases affinity

• Deoxy Hb and H+ binding causes a change in histidine residues. histidines pKa shifts

• Histidine becomes protonated, and this can stabilize the T, low affinity states of heme

• and vise versa, at a higher pH, less CO2 is in blood and oxygen can bind to hemoglobin tighter

2,3-DPG as an allosteric regulator

a side byproduct of glycolysis (so upregulated in an anerobic state)

• decreases and attenuates hemoglobin affinity for oxygen for hypoxic conditions

• found in anemic, altitude sickness, pregancy

fetal hemoglobin (Hb F)

• higher affinity than adult varient so it can take oxygen from mom’s blood

• gamma chain has decreased affinity for 2,3 DPG

carbon monoxide poisioning

• CO has a much higher affinity for heme iron than oxygen

• this locks hemoglobin in R state, so increases heme affinity

• cannot release oxygen to tissues

hemoglobinopatheies

• structural Hb varients- sickling disorders, instability, can be aquired like A1c

• thalasemmias- reduced rate of globin chain production

• Herditary persistence of fetal Hb- a deletion or nondeletion

sickling disorders

can be homo or heterozygous

• common varients: Hbs C, D, E

• point mutations in adult beta globin

• HbS Glutamine is turned to a valine. affects folding. hemoglobin forms fibers.

• HbC turns a glutamine to lysine

• causes anemia in homozygous, sicke cell increases cell lysis

thalasemmias

a group of disorders of Hb synthesis

• alpha and beta chain relative concentrations are unequal

• hypocromic and microcytotic anemia

• typically is compensated by a persistence HbF production

beta thalasemmias

• normal alpha globin, beta chain is defective. can be caused by many mutation types

• HbA is inhibited

• HbA2 (Delta and alpha chains) and HbF are intact

• can cause premature lysis of RBC since extra alpha chain can precipitate

alpha thalasemias

deletion mutation in alpha gene

HbA1c

• glycosalation product when blood sugar is too high

• increases heme affinity for oxygen, less in tissues

• can stress endothelial cells

• alters gene expression that can affect cell cycle and immune response

• reduced white matter

MetHb

methemoglobin, a byproduct of glycolysis

• NADH can be oxidized to reduce cytochrome b5

• cytochrome b5 oxidizes hemeoglobin to form Fe3+ hemoglobin

• is reversable by NADH and NADPH

methemoglobinemia

makes it so hemoglobin cannont bind or release O2, can cause cyanosis

• a deficiency in NADH cytochrome b5 methemoglobin reductase that can reverse MetHb

• can be caused by some meds or drugs

• 15% concentration of MetHb is associated with skin and blood color changes, more than that can cause neurologic and cardiac symptoms, more than 70% is fatal

antihypertensive mechanism of action

Mean arterial pressure = cardiac output times total peripheral resistance

• antihypertensives affect one of these factors

• cardiac output is heart rate times stroke volume

anatomic sites of blood pressure controll

• resisnce at arterolies

• kindey hormones affecting volume

• capacitance in venules

• heart output

antihypersinves level of impact

• primary- directly on sympathetic nervous system to adjust vascuar tone. acts fast, but body fights back!

• secondary- long term modulation of renin-angiotensin-aldosterone system for renal fluid regulation

• tertiary- local, endothelial factors. Nitric oxide for vasodilation, endothelin 1 for vasoconstriction

how can cardiac output be modulated

• heart rate- beta blockers lower

• stroke volume- can be influenced by preload, afterload, and contractility

• preload- lowered by nitrates and diuretics

• afterload- reduced by vasodilators, ace inhibitors, ARBs

• contractility- increased by digoxin, decreased by beta blockers

what determines total peripheral resistance (systemic vascular resistance)

increased by

• sympathetic nervous system

• renin-angiotesin-aldosterone system (RAAS)- also increases H2O and sodium retention

• endothelial factors like endothelin

• local autoregulation through myogenic or metabolic mechanisms

causes of hypertension

about half of adults in the US have hypertension

• primary- caused by lifestyle or genetics

• secondary- has an identifable cause such renal disease, endocrine disorders.

RAAS inhibitors

regulate stroke volume and resistance

• ACEi (-prils), ARBs (-sartans), Direct Renin inhibitors, MRAs

• contraindicated in pregnancy

• dilate efferent arteriole in kidneys, reducing glomerular pressure and protects kindeys with chronic kindey disease

ACEi mechanism

blocks Ang II conversion and causes bradykinin accumulation. can cause:

• dry cough

• angioedema

ARBs mechanism

blocks AT1 receptors. can cause:

• hypotension

• no cough since there is no bradykinin increase

Direct renin inhibitors (DRI) mechanism

Aliskiren: binds to rein enzyme to stop cascade. can cause:

• hyperkalemia

• renal impairment

• Do not take with ACEi or ARBs

• helps in congestive heart failure

MRAs

(-one drugs), aldosterone antagonist, potassium sparing diuretic. can cause

• hyperkaleima

• block androgens, can cause gynecomastia (female sex characteristics)

central alpha 2 antagonists

stimulates pre-synaptic a2 receptors in the brain, negative feedback decreased norepinephrine release.

• clonidine- withdraw causes rebound hypertension

• methyldopa- can be used in gestational hypertension

• guanfacine

selective alpha 1 blockers

(-zosins) prevent norepinephrine from constricting vessels

• prazosin, doxazosin, terazosin

• first dose phenomenon- first dose can cause intense hypotension

• reflex tachycardia, BP drop triggers baroreceptors to increase heart rate

sympatholytics- beta blockers

ment to reduce vascular resistance without inducing tachycardia, no reflex tachycardia

• cardioselective: B1 receptor only, can decrease heart rate and supress RAAS

• nonselective: affects B1 and B2

• mixed: a and b

thiazide diuretics

first line hypertensive, blocks Na/Cl symporter in distal convoluted tubule. can cause:

• hypercalcemia, hyperglycemia, hyperuricemia

loop diuretics (-semide)

for heart failure and pulmonary edema: blocks Na/K/2Cl cotransporter in the ascending loop of henle. can cause:

• hypocalcemia, hypokalemia, ototoxicity

potassium sparing diuretics

block the epithelial sodium channels in collecting duct, is independent of aldosterone

• amiloride, triamterene

• weak on their own, typically in combination

• can cause hyperkalemia (especially combined with ACEi or ARBs or in pt with kindey failure.)

how do diaretics lower blood pressure

• initially, it reduces stroke volume but will reover

• ultimately reduces total peripheral resistance

vascular selective calcium channel blockers (DPH)

(-dipine), blocks L-type calcium channels to reduce smooth muscles contraction

• can cause edemia, tachycardia, flushing

• synergistic affect with beta blockers

cardiac selective calcium channel blockers (non-DPH)

blocks L-type calcium channels in heart, reduces rate, AV nodal conduction, and contractility

• verapamil and diltiazem

• can cause bradycardia, cardiac block (NOT IN THOSE WITH SYSTOLIC HEART FAILURE)

• DO NOT COMBINE WITH A BETA BLOCKER

nitric oxide based vasodilators

• dilation in artertioles reduces cardiac after-load, same vasodilation cascade as normal. Hydralazine

• dilation in capacitance veins reduced preload. Nitroglycerine and Dinitrate

nitrated vasodilator side effects

• headahce due to meningial vessel dilation, progresses to flushing, dizyness, and orthostatic hypotension

• causes reflex tachycardia, percribes with a Beta Blocker to prevent

dopamine 1 agonists: fenoldopam

rapid vasodilation, used only in hypertensive emergencies

alveolar lining fluid

• generates surface tension through water in it

• sphere has the least amount of air-water interface to prevent collapse

• still needs surfactants (made of lipids and some proteins) to reduce surface tension more.

DPPC

dipalmitoyal phosphatidyl choline

• primary lipid in lung surfactants

• contains 2 16 carbon palmitic acid chains with a phosphatidylcholine polar head

• linear, saturated fatty acid

• forms a monolayer at air-water interface. breaks up bonds between adjacent water molecules to break surface tension.

pulmonary surfactant componentes

• DPPC (1/3)

• unsaturated fatty acids(1/3)

• proteins (10%)

• phosatidylglycerold (PG) (10%)

• some cholesterol

proteins in pulmonary surfactants

• SP-A - immune defence, recycling and secretion of surfactant

• SP-B- prevent collapse

• SP-C- prevent collapse

• SP-D- immune defence

what happens if alveoli shirnk

• typically caused by less surfactant, but by spring the concentration of surfactants increase so it can only shrink so much.

• pressure within alveolus goes up, also increases the fluid layer to stabilize size.

amniotic fluid

produced by fetus by kidneys

• helps promote lung growth

• so kindey issues can affect lung growth

DPPC biosynthesis

• two fatty acyl COA molecules are added glycerol 3 phosphate by acetyltransferase. produces phosphatidic acid (not nessicarily with a palmitic acid R group)

• choline (from diet) gains a phosphate from ATP then modified with CTP, produces CDP-choline

• CDP-choline reacts with DAG (from phosphatidic acid) to form phosphatidylcholine. A CMP is released

• LPCAT modifies any R groups to be palmitic acid (16c)

what foods have choline

in the form of phosphatidylcholine (lecithin)

• common in many foods, can be a vitamin

• body does make lecithin, but not a lot. mainly only in lungs

• a deficiency is most commonly seen on exclusively intravenous feeding. presents as a fatty liver since there is less VLDL’s being released into blood

eicosinoids

small 20 carbon lipid molecules derived from arachidonic acid

• contributed to prostaglandins, thromboxanes, and leukotrienes- paracrine signaling in most cells

• very short half lives, contributes to localized effect

• pathologic physioloic functions

• interact with g-protein receptors, mainly PKA

eicosanoid biosynthesis

• esental fatty acid linolenic acid

• creates arachidonic acid, will be incorperoted in the membrane.

• in response to a signal, phospholipase A2 will release arachidonic acid from phosphatidylcholine and phosphatidylethanolamine

• released arachidoic will be in the cell, where it can be modified into many types of cell signaling

PGH2

from arachidonic acid, first prostoglandid produced after liberation from membrane

• coverted by PGH2 synthase: first acts as a cyclooxygenase and then a peroxidase

• PGH2 can be converted into several inflamatory molecules

COX-1 vs COX-2

• 1: made in most issues

• 2: in inducable in some tissues as a response to inflamation

products from PGH2

• thromboxane A2: activates platelets, vaso and bronchoconstriction, smooth muscles contraction

• Prostacyclin (PGI2): promotes vasodilation, produced by COX-2

• prostacyclin E2 (PGE2): promotes vasodilation

• Prostaglanded F2n (PGF2n): vaso and bronchous contsriction, smooth muscles contraction

• Leukotrienes: several types, vaso and bronchoconstriction, smooth muscles contraction, increase vascular permiability. involved in allergies and asthema

how is the production of eicosinoids controlled

• corticosteroids inhibit aracadoinc release from membrane

• asprin inhibit COX 1 and 2, the cyclooxengease step to create PGH2

• celecoxib inhibits COX 2

glucocorticoid receptor- dimer

transactivation

• localized in cytoplasm, bound to Hsp90

• Steroids can enter the cell, and will bind to receptors. Hsp90 dissasociate and will dimerize, receptor goes to nucleus

• in nucleus, HAT is activated to acetylate histones. increases transcription, one being Annexin A1

• Annexin A1 allosterically inhibit phospholipase A2

glucocorticoid receptor- monomer

transrepression

• same starting steps, when Hsp90 dissasociate it raimains a monomer.

• as a monomer, it goes to nucleus and decreases gene expression associated with inflamation by booting transcription factors.

• work in both meachanisms synergistically.

leukotriene production

• starts with arachidonic acid, but instead of PGH2, 5-lipoxygenase produces the intermediate

• from here, many kinds of leukotrienes are made depending on cell

• inhibited by glucocorticosteroids, unaffected by asprin

• zileuton is the drug inhibitor

leukotrienes and asthema

as they induce broncoconstruictrion and inflamation, express leukotrienes are associated with asthema

• much more potent than histamine as a broncroconstrictor

• can also recruit cells that make it worse

• drugs like singular (montelukast) target leukotrines to relive asthma symptoms

blood flow controll mechanism

• acute: local level, mainly affects resistance vasculature like arterioles, metarterioles, precapillary sphincters. fast response

• chronic: slow and controlled over days or months

acute controll

• increases tissue metabolism (such as exercise or other short burst activity) increases tissue blood flow. a four fold increase of metabolism correlated to a 2 fold increase of blood flow.

• reduced oxygen availability also increases blood flow. if oxygen saturation is a fourth of normal, blood blow increases by 3 fold.

vasodilator theory

vasodilator substances form in response to increased metabolism or decreased oxygen, and will determine blood flow changes. these will diffuse through resistance vasculature to vasodilate vessels.

oxygen demand theory

since oxygen is required for contaction, in hypoxic conditions the muscle automatically relaxes.

• creates cyclinc phases of relaxation/contraction called vasomotions

• precapillary sphincters are closed as O2 levels are high

other nutrients that contribute to local blood flow

• lack of glucose can cause local vasodilation

• Vit B deficiency causes nearly whole-body peripheral blood flow to double (since they are required for ATP production). can directly reduce smooth muscles contraction

reactive hyperemia

• blood flow to a tissue is blocked for some time

• when block is removed, blood flow will increased by 4-7 fold

active hyperemia

• tissues is very active, so blood flow must increase

• vasodilator substances are released, local blood flow is increased

blood flow autoregulation mechanisms

when arterial pressure rises and blood flow increases. within a minute, blood flow (and vasodilation) will return to normal even if pressure is still elevated

• metabolic regulation- high arterial pressure will deliver too much oxygen and flush out vasodilators. will return blood flow to normal

• myogenic regulation- when a small blood vessel is stretched, they will contract in response.

stretch-induced vascular depolarization

stretch is sensed by smooth muscles, incuces calcium influx, will trigger vessel contraction