Hepatobiliary and Pancreatic Flashcards
Amino acid changes in PSS?
Increased aromatic: tyrosine, phenylalanine
Decreased branched chain: leucine, isoleucine, valine
MicroRNAs in hepatic disease?
Chronic hepatitis - miR-126/122/29a. 122 corr with fibrosis. Increase ET1 too
miR-200 hepatocell carc
mrR21/122 mucocoele
mrR122 gen hepatic dz (
Dermatological presentation of hepatic disease?
Superficial necrolytic dermatitis
Compounds associated with hepatic encephalopathy?
Increased: ammonia, aromatic AAs, endogenous benzodiazepines, gamma-aminobutyric acid (GABA), glutamine, phenol. short chain FAs, tryptophan, false NTs
Decreased: alpha-ketoglutarate
What is the half life of ALT, ALP and AST in dogs and cats?
ALT: 48-60/6
AST: 22h/77m (nb 20 % in mitochondria)
ALP: 70/6
What links ALP to cell membranes? Why is it released in cholestasis?
Glucosyl phosphatidyl inositol linkage
Cholestasis - bile acids detergent, increased glucosylphosphatidylinositol phospholipase activity
When is GGT increased?
Zone 1 peri portal disease
When do steroids start increasing ALP?
mRNA 24-48h, expression gene 10d
Mechanism of RBC changes in hepatobiliary disease?
Microcytosis - impaired iron transport
Target cells/poikilocytes - altered RBC cell membrane lipoprotein content/deformability
Anaemia - chronic dz, haemorrhage
Thrombocytopenia - sequestration, decreased thrombopoietin
Why do dogs have bilirubin in urine?
Can conjugate it renal - have enzymes - esp males, plus low renal threshold
Mechanism of ammonium biurate stones?
No uric acid conversion to allantoin (uricase)
Low USG?
Loss medullary hypertonicity, decreased cortisol metabolism, psychogenic
Glucose?
Decrease when 75 % liver gone - decreased glycogen stores, gluconeogenesis, insulin clearance and glucagon response
Increase in globulin?
Decreased filtration and clearance of toxins and bacteria
How is ammonia incorporated into the urea cycle?
Carbamoyl phosphate synthesise 1 (helped with nacetylglutamate)
What is more sens/spec - single BA, fasting NH3, pre and post BA PSS?
Sens - pre + post BA then ammonia then single BA
Spec - ammonia > BA
Urine versus serum BAs?
Increased specificity lower sens HEPATOBILIARY
Equivalent serum in cats
Lower sens PSS
Values of ammonia for PSS?
> 45 - 98/89 % sens/spec
Don’t do tolerance test if > 150 basal
What clotting factor does the liver not produce?
vonWB subtype of VII
Protein C?
Binds protein S to degrade V and VIII clotting factors
Decreased in PSS vs PVH
What is used to conjugate bile acids?
Glycine/taurine
Bile salt hepatocyte export and import?
Bile salt export pump (multi drug resistance associated protein 2)
Sodium dependent taurochlorate cotransporter
Ileum - apical sodium bile acid cotransporter
What transports bilirubin and bile acids in blood?
Organic ion transporting polypeptide
Top end normal CBD cat/dog?
< 4 <3
Sensitivity of AUS for PSS? CT?
80 - 100 epss, 100 IPSS
Portal vein:aorta < 0.8 v sensitive, < 0.65 - PSS
CT - 96 sens 89 spec - 5.5 x more likely than AUS
AUS with MAPSS? Sensitivity?
Left dorsal renal, 60 %, splenorenal
Contrast enhanced hepatic ultrasonography?
Decreased perfusion in malignant
Increased enhancement benign lesions esp late phase
MRI more sens PSS than CT?
No - less - but more specific
Incidence of haemorrhage after tru cut bx?
Cat - probably around half major haemorrhage but not corr with coags
Stains for liver?
Rubeanic acid/rhodanine - copper
Sudan - lipid
PAS - glycogen
Masson’s trichrome/sirius red fibrosis
Utility of FNA for liver disease?
Highest sens vac change and neoplasia (50 % each)
Tru cut liver?
NB vagotonic shock with autofire
Discordant with wedge half the time (better if neoplasia)
Increased concordance 14 G - more portal triads
Goals of therapy in liver dz?
Address underlying cause
Decrease or prevent inflammation, oxidative damage, fibrosis and copper accumulation
Provide nutrition
Manage complications
Major bile acids?
Chenodeoxycholic acid and cholic acid from cholesterol hydroxylation form trihydroxy bile acid taurocholate
Mechanism of action SAM-e
Synthesis of glutathione via homocysteine transmethylation and transsulfuration pathway
Prevent hepatic glutathione depletion
Modulate apoptosis, anti-inflammatory, anti carcinogenic, improve membrane structure, fluidity and function
Inhibits pro-inflamm cytokine production, prevents development of oxidative stress, improved redox status
Increases hepatic GSH (and amount of reduced GSH), decrease oxidised glutathione disulphide form
Does not prevent vacuolar hepatopathy
Decrease level of hepatic enzymes and amount of tx delay when combined with silymarin in dogs tx lomustine
N-acetylcysteine?
Formation L-cysteine, precursor of glutathione
Stabilises glutathione conc, improves redox status
Silymarin?
Flavanoligans including silybin - most biologically active around 50 - 70 %
Antiox: free radical scavenger, decreased lipid per oxidation, suppress hydrogen peroxide/superoxide/lipoxygenase, increase glutathione
Anti-inflamm: decrease TNFalpha/IL1beta/NFkappabeta, inhibit kuppffer cells
Anti-fibrotic: decrease hepatic stellate cell activity and decrease hepatic collagen expression
Might be choleretic
Increase bioavailability if give with phosphatidylcholine
Amanita phalloides tox, lomustine
What enzyme conjugates bilirubin?
UDP glucuronosyltransferase
Vit E mechanism?
Alpha tocopherol most biologically active
Antioxidant: protect phospholipid from oxidant injury, scavenge free radicals, minimise lipid peroxidation
Ursodeoxycholic acid?
Hydrophilic bile acid - displace toxic hydrophobic ones from circulating pool. Increase fluidity of bile.
Choleretic (protonated UCDA absorbed by biliary epithelial cells and leaves bicarb - bicarb draws water)
Inhibit hepatocyte apoptosis
Decrease IL1/2, B lymph AB, (immunomodulatory)
Stabilise mitochondrial function
Increase glutathione (increase methionine adenosyl transferase activity to generate SAMe)
Anti-fibrotic - NAFKB
D-penicillamine?
Copper chelator and anti-fibrotic (prevents collagen molecule cross linking)
Zinc?
Increase metallothionein synthesis by enterocytes to bind copper
How to manage fibrosis in hepatic disease?
Caused by increase in stellate cell and fibroblast activity - steroids for latter, decrease ox injury for former as increases stellate cell activity
What precipitates hepatic encephalopathy?
Increased ammonia production in the GI tract:
Poor quality poorly digestible protein, or excess protein in diet - reaches colon for bacterial degradation
Constipation
GI haemorrhage
Azotaemia (increases systemic ammonia generation)
Blood transfusion of stored blood
Protein calorie deficiency and catabolism
Factors influencing the CNS uptake or metabolism of ammonia:
Alkalosis
Hypokalaemia
Hypoglycaemia (potentiates activity and production of neurotoxins)
Inflammation (cytokines are neurotoxic and potentiate ammonia)
Sedative and GA drugs
What effect does ammonia have in the CNS?
Inhibitory. Depletes glutamate and alters glutamate receptors, impairs mitochondrial function.
Taurine defiency?
Important in cats - conjugation of bile acids, take from muscle if depleted
NB neck ventroflexion!
Important amino acids in cats?
Taurine, arginine, methionine, cysteine
Cell cycle inhibitors in chronic hepatitis?
Increase p21, cell senescence, correlated with survival.
Evidence for immune mediated aetiology in chronic hepatitis?
Lymphocytic inflammation
MHC Class II haplotype association (ESS/Dobermann)
Positive serum autoABs, antihistone ABs (Doberman)
Familial association (Dob, lab, westie)
Assoc with other immune disorders (lab)
Female (dob, lab, ess, acs)
Response to immunosuppressives
Age CH in diff breeds?
Dalmatian, dobermann and ESS younger
Lab, ECS, Cairn older
ACS younger than ECS
Signalment for lobular dissecting hepatitis?
Younger
Standard poodle, ACS, rottie, GSD, Gret
80 % have ascites
Best screening test for CH?
Increased ALT more than 2 months
Indicators of portal hypertension?
GI/gall bladder/pancreatic oedema, decreased portal vein velocity, hepatofugal flow
Decreased protein C, PV:aorta <0.65, anaemia, microcytosis, increased ammonia and bile acids
Difference between chronic hepatitis and lobular dissecting hepatitis on histopath?
Minimal inflamm in latter
Cirrhosis
Fibrosis with nodules
Factors to consider when predicting bleeding risk in CH?
PT/aPTT 1.5 x upper RI plt <50 PCV < 30 Fibrinogen < 100 vWF < 50 % BMBT > 5min
Where should a sample for copper be collected from?
Least affected region
How many portal triads do you need to make dx?
12 - 15 (but sometimes don’t need that many if v obvious widespread disease)
Evidence for immunosuppressive tx in CH?
Pred:
Increased length of survival time dobermans
Complete remission around 1/3
ESS - imp enzyme bili and survival
Labs increased survival cf historic controls with combo aza - MST 630 d
Ciclosporin:
Remission in 76 %
What to do if granulomatous inflammation on hepatic bx?
Search infectious dz
CH survival time?
Around 600 d
Negative CH px factors?
Ascites (not cockers) cirrhosis, lobular dissecting hepatitis, hypoglycaemia, hypoalphaglobulin, hyperbili, decreased plt, increased coags, fibrosis, necrosis, bridging/marked fibrosis, small liver, portal lymphadenopathy, SIRS, clinical score
How often is copper the cause of CH?
Around a third depending on breed (cupric oxidation state Cu2+ is hepatotoxic, gen O2 free radicals)
How might copper accumulate?
Increased diet, primary defect in metabolism, altered biliary excretion
Toxicity depends on concentration, molecular association and sub cellular localisation
Bedlington?
Copper metabolism gene MURR1 containing domain 1) - auto recessive
Labrador copper mutation?
ATP7B/A (copper excretor, COMMD1 acts on it) ALSO DOBERMAN ATP7B
ATP7B = ceruloplasmin - biliary excretion - Wilson’s dz
NB COMMD1 NOT described in dobermans/lab
Cat - ATP7A/B
How often is copper accumulation detected in feline liver biopsies?
12 %, NB lower RI for cats
Major copper assoc CH breeds?
Bedlington, Dalmatian
Lab, doberman (female predip)
Westie, skye terrier
What is ATP7A?
Basolateral enterocyte copper transporter - upreg = more Cu absorb
What transports copper from the GI lumen?
Copper transporter 1