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QBank Qs > Hepatobiliary 1 > Flashcards

Hepatobiliary 1 Flashcards

1
Q

Are introns transcribed?

A

They are not translated during protein synthesis, but they are not transcribed by RNAP II during RNA production.

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2
Q

What is the purpose of the 3’ poly-A tail? Is it transcribed?

A

It protects the mRNA from degradation within the cytoplasm after it exits the nucleus, but it is not transcribed from DNA - it is added by post-transcriptional modification

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3
Q

Why do women with hemochromatosis present later than men?

A

Physiologic iron loss through menstruation and pregnancy slows the progression of hemochromatosis in women.

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4
Q

What is defective in hemochromatosis?

A

There is a defect in the intestinal absorption of dietary iron that results in excess absorption and storage of 0.5-1g of iron each year.

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5
Q

How do ethanol and vitamin C affect iron stores?

A

increase reabsorption of iron

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6
Q

What type of liver malignancy can be associated with hemochromatosis?

A

hepatocellular carcinoma

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7
Q

What is the most common benign liver tumor and how does it present?

A

Cavernous hemangiomas - consist of cavernous, blood-filled vascular spaces of variable sizes lined by a single epithelial layer

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8
Q

What are the 5 enzymes required by pyruvate dehydrogenase?

A

CoA, FAD, lipoic acid, NAD, and thiamine pyrophosphate

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9
Q

What is the result of decreased pyruvate dehydrogenase activity?

A

pyruvate will be converted to lactate instead of acetyl CoA in order to regenerate NAD+ which will lead to lactic acidosis

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10
Q

Other than pyruvate dehydrogenase, what else does lipoic acid serve as a cofactor for?

A

alpha-ketoglutarate dehydrogenase adn branched-chain ketoacid dehydrogenase

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11
Q

What is a urea cycle disorder resulting from a deficiency of argininosuccinate synthetase?

A

Citrullinemia

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12
Q

What are the two pathways that dispose homocyteine from the body?

A
  1. conversion of homocysteine to cysteine by the actions of two vitamin B6 enzymes: cystathionine synthase and cystathionase
  2. conversion of homocystine to methionine by folate and vitamine B12-dependent process
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13
Q

What occurs d/t defective pyrimidine synthesis resulting from a deficiency of the enzyme orotate phosphoribosyl transferase and requires glutathionine as a coenzyme?

A

orotic aciduria

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14
Q

What should be suspected in all pts with premature onset (

A

alpha-1 antitrypsin deficiency

-neonatal hepatitis with cholestasis should increase suspicion

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15
Q

What are the most severe consequences of liver involvement in alpha-1 antitrypsin deficiency?

A

cirrhosis and hepatocellular carcinoma

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16
Q

What does a northern blot detect and what type of probe is used?

A

RNA via ssDNA or RNA (hybridization) probe

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17
Q

What does a southern blot detect and what type of probe is used?

A

DNA via ssDNA or RNA (hybridization) probes

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18
Q

What does a western blot detect and what type of probe is used?

A

protein via antibody probe

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19
Q

What does a southwestern blot detect and what type of probe is used?

A

DNA-binding protein via dsDNA probe

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20
Q

What does Ras activate?

A

MAP kinase

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21
Q

What are homodimeric calcium-binding proteins that serve as markers for cells of neural crest derivation (melanocytes and Schwann cells), as well as Langerhans cells and other dendritic cells?

A

S-100 proteins

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22
Q

What are nuclear transcription factors that directly bind DNA via leucine zipper motif?

A

c-Jun and c-Fos

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23
Q

How is the liver involved in the metabolism of TGs?

A

TGs stored in adipose tissue is metabolized into FFAs and glycerol by lipase. Glycerol is transported into the liver and phosphorylated to glycerol-3-phosphate by liver-specific glycerol kinase which is then converted to DHAP by glycerol-3-phosphate dehydrogenase. DHAP is used to produce ATP through glyoclolysis or glucose through glyconeognesis. Glycerol in the liver can be utilized for TG synthesis

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24
Q

What reaction catalyzes FA activation to acyl-CoA form in urder to undergo B-oxidiation in the mitochondria?

A

acyl-CoA synthetase

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25
Q

What must fatty acyl-CoA conbine with in order to be transported into the mitochondrion?

A

carnitine

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26
Q

What is the first enzyme used in the HMP shunt and whoulat does it produce?

A
  • glucose-6-phosphate dehydrogenase

- produces NADPH and pentose sugars for nucleotide synthesis

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27
Q

Where do fatty acid oxidation and synthesis occur respectively?

A

oxidation: mitochondria
synthesis: cytosol

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28
Q

What catalyzes the first committed step in fatty acid synthesis, and what is this step?

A

acetyl CoA carboxylase (ACC) converts acetyl CoA to malonyl CoA

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29
Q

What organis can utilize ketone bodies for energy?

A

skeletal muscle, cardiac muscle, renal cortex, and brain (during starvation)

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30
Q

Why is continuous energy supply via ketone bodies important during prolonged starvation?

A

The brain has no glycogen or triglyceride stores

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31
Q

Why can’t erythrocytes utilize ketone bodies?

A

they lack mitochondria

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32
Q

Why can’t the liver utilize ketone bodies for energy?

A

the liver lacks the enzyme succinyl CoA-acetoacetate CoA transferase (thiophorase), which is required to convert acetoacetate to acetoacetyl CoA

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33
Q

Which to organs cannot utilize ketone bodies for energy?

A

RBCs and liver

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34
Q

What is a middle-aged Caucasian female with long history of pruritis and fatigue who now develops pale stoles and xanthelasma suggest?

A

primary biliary sclerosis

xanthelesma and pale stool suggest cholestasis

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35
Q

What is primary biliary cirrhosis (PBC) and what is found on histology?

A

PBC is a chronic liver disease characterized by autoimmune destruction of the intrahepatic bile duct and cholestasis. Histo findings include destruction of interlobular bile ducts by granulomatous inflammation (florid duct lesion) and a heavy portal tract infiltrate of macrophages, lymphocytes, plasma cells, and eosinophils.

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36
Q

What is suggested by a middle-aged obse female with fever and a prolonged episode of severe RUQ pain after fatty meal ingestion?

A

acute cholecystitis (rather than biliary colic, which is typically briefer and without fever)

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37
Q

What is suggested by a male with a long history of ulcerative colitis presenting with fatigue and high alkaline phosphatase?

A

primary sclerosing cholangitis

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38
Q

What is suggested by n older female with weight loss, abdominal discomfort, jaundice, and an epigastric mass?

A

pancreatic cancer

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39
Q

What is suggested by a homeless man with fever, abdominal pain, and jaundice?

A

acute cholangitis

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40
Q

What is the most common cause of galactosemia and what is excess galactose converted to?

A

deficiency of galactose-1-phosphate uridyl transferase

-galactose is converted to galactitol

41
Q

What are the clinical features of galactosemia?

A

vomiting, lethargy, jaundice, and failure to thrive soon after breastfeeding

42
Q

What are the 3 stages of alcoholic liver injury?

A

alcoholic steatosis, alcoholic hepatitis, and cirrhosis

43
Q

What does hepatocyte injury lead to ?

A

release of intracellular enzymes and an increase in serum transaminases and serum bilirubin

44
Q

What are indicators of the liver’s synthetic function?

A

serum albumin level and elevated prothrombin time

-hypoalbuminemia and prolonged PT (=decreased coag factor synthesis) indicate poor prognosis

45
Q

What is the role of serum GGT when alkaline phosphatase is elevated?

A

serum GGT can differentiate whether the cause is biliary disease or alternative cause of elevated alkaline phosphatase like bone disease
*GGT are specific for biliary injury

46
Q

What causes prolonged bleeding time in alcoholic liver disease?

A

thrombocytopenia d/t direct toxic effects of alcohol on bone marrow and hypersplenism and splenic sequesteration of palteets

47
Q

What are indicators of hepatocellular damage?

A

AST and ALT

48
Q

What markers have the greatest prognostic significance?

A

serum albumin level and PT

49
Q

Where do all the reactions of the pentose phosphate pathway occur?

A

in the cytosol

50
Q

What is transketolase involved in and what does it use as a cofactor?

A

involved in PPP and uses thiamine

51
Q

What is the importance of the 16S rRNA strand in prokaryotes?

A

It is essential for intiation of protein synthesis in prokaryotes and expresses a complementary sequence to the Shine-Dalgarno sequence in mRNA which allow mRNA and 30s subunit to bind in preparation for protein translation

52
Q

Deficiency of what leads to incomplete glycogen degradation?

A

Debranching enzymes deficiency (Cori disease)
-alpha-1,6-glucosidic branch points cannot be degraded, so small chain dextrin-like material accumulates within the cytosol of the hepatocytes

53
Q

What are the Sx of Cori dz?

A

hypoglycemia, hypertriglyceridemia, ketoacidosis, and hepatomegaly

54
Q

What causes confusion, ophthalmoplegia, and ataxia in an alcoholic pt?

A

Wernicke encephalopathy

55
Q

What does a-ketoglutarate dehydrogenase requires thiamine as a cofactor?

A

thiamine

56
Q

Why does administration of glucose to a thiamine-deficient pt result in Wernicke encephalopathy?

A

d/t increased thiamine demand

57
Q

What is the MOA of Zidovudine (AZT)?

A

It is a nucleoside RT inhibitor for HIV and it competitively binds to RT and is incorporated into the viral genome as a thymidine analog. AZT does not have a 3’-OH group, making 3’-5’ phosphodiester bond formation impossible

58
Q

What infection can cause hepatic abscess through hematogenous seeding of the liver?

A

S. aureus

59
Q

What are the clinical manifestations of Reye syndrome?

A

-hepatic encephalopathy: increased AST, ALT, NH3, PT, and PTT
-encephalopathy d/t hyperammonemia in CNS leading to cerebral edema
-

60
Q

What are the histologic manifestations of Reye syndrome?

A

microvesicular steatosis of hepatocytes without inflammation and cerebral edema

61
Q

What is charcterized by autoimmune destruction of the interaheptic bile ducts and cholestasis by anti-mitochondrial antibodies?

A

primary biliary cirrhosis (PBC)

62
Q

How do primary biliary cirrhosis and graft vs. host disease have similar presentations?

A

they both demonstrate granulomatous bile duct destruction and a heavy lymphocyte-predominant portal tract infiltrate

63
Q

What are the Sx of low-grade fever, anorexia, nausea, dark colored urine, and RUQ tenderness classic for?

A

acute hepatitis

64
Q

What are histologic findings of all acute viral hepatitis?

A
  • diffuse ballooning degeneration (hepatocyte swelling)
  • mononuclear cell infiltrates
  • Councilman bodies (eosinophilic apoptotic hepatocytes)
65
Q

What leads to the formation of brown pigment stones?

A

They arise secondary to infection of the biliary tract, which results in the release of B-glucoronidase by injured hepatocytes and bacteria

66
Q

What is the function of B-glucuronidase by injured hepatocytes and bacteria?

A

contributes to hydrolysis of bilirubin glucuronides and increases the amount of UCB in the bile

67
Q

What is the MOA of hepatocyte injury by HBV?

A

the presence of HBsAg and HBcAg on the cell surface stimulate the host’s cytotoxic CD8+ T lymphocytes to destroy infected hepatocytes

68
Q

What is usually the first Sx of primary biliary cirrhosis?

A

pruritis

69
Q

How is PBC diagnosis confirmed?

A

anti-mitochondiral Abs in the serum

70
Q

What are physical findings in PBC?

A

hepatosplenomegaly and xanthomatous lesions in the eyelids or skin and tendons

71
Q

what are associated conditions with PBC?

A

Sjogren, Raynaud, scleroderma, autoimune thyroid disease, hypothyroidism, and celiac

72
Q

What is the pathogenesis of alcohol-induced hepatic steatosis?

A

it is related primarily to a decrease in free fatty acid oxidation secondary to excess NADH production by the 2 major alcohol metabolism enzymes, alcohol dehydrogenase and aldehyde dehydrogenase

73
Q

What is the molecular mechanism of hemochromatosis?

A

The hemochromatosis gene (HLA-H) is on the short arm of chromosome 6 and encodes for a molecule that appears to affect iron absorption from the GI tract

74
Q

How is hepatocellular carcinoma associated with HBV infection?

A

integration of viral DNA into the genome of host hepatocytes triggers neoplastic changes

75
Q

What are properties of drugs that have high intrinsic hepatic clearance?

A

high lipophilicity and a high volume of distribution via bile breakdown into the feces
-high lipophilicity allow drugs to cross cell barriers more easily and enter hepatocytes

76
Q

What is is impaired with carnitine deficiency?

A

It reduces the ability of fatty acids to enter the mitochondria for B-oxidation

77
Q

What does B-oxidation of fatty acids produce?

A

acetyl CoA, a precursor of acetoacetate (one of the three primary ketone bodies)

78
Q

What should a moderately elevated alkaline phosphatase of unclear etiology be followed up with?

A

GGTP

79
Q

What are the normal levels for total and direct bilirubin, respectively?

A

total: 0.2-1 mg/dL
direct: <0.2 mg/dL

80
Q

What is Gilbert syndrome?

A

A familial disorder of bilirubin glucuronidation in which the produciton of UDP glucuronyl transferases is reduced

81
Q

What are lab findings for acute viral hepatitis?

A

ALT > AST, followed by rises in bilirubin and alkaline phosphatase

82
Q

What is the MOA of statins?

A

inhibit RLS of HMG-CoA reductase in cholesterol biosynthesis

83
Q

What are the SE of statins?

A

hepatotoxicity and muscle toxicity

84
Q

What is the MOA of fibrates?

A

increased LPL activity, decreased hepatic VLDL secretion, increased HDL synthesis

85
Q

What are the SE of fibrates?

A

muscle toxicity, especially when combined with statins and gallstones

86
Q

What is the MOA of bile acid sequestrants?

A

binds bile acids in the intestine, decreases reabsorption, and increases de novo synthesis from cholesterol

87
Q

What are the side effects of bile acid sequestrants?

A

nausea, bloating, cramping, decreased absorption of digoxin, warfarin, and fat-soluble vitamins

88
Q

What is the MOA of niacin?

A

decreased lipolysis in adipose tissue causing decreased VLDL synthesis in liver; increased HDL by reducing clearance

89
Q

What are the SE of niacin?

A

flushing, warmth, and pruritis

hepatotoxicity

90
Q

What is the MOA of Ezetimibe?

A

decreased cholesterol absorption at the brush border of the intestine

91
Q

What are the SE of ezetimibe?

A

increased hepatotoxicity when coadministered with statins

92
Q

What is the inheritance pattern of classical galactosemia?

A

autosomal recessive

93
Q

What is HBV associated with in the prodromal period?

A

serum-sickness like syndrome

94
Q

How does hyperestrinism in alcoholic cirrhosis occur and what are Sx?

A
  • decreased catabolism of estrogens and increased sex hormone-binding globulin (decreases T:E ratio)
  • Sx: gynecomastia, testicular atrophy, decreased body hair, and spider angiomata
95
Q

What is a rare autosomal recessive disorder characterized by an asymptomatic conjugated hyperbilirubinemia that results from numerous defects in the hepatic uptake and excretion of bilirubin pigments?

A

Rotor syndrome

96
Q

How does hepatocyte injury with viral hepatitis present?

A

diffuse swelling termed “ballooning degeneration” which causes the cytoplasm to appear empty with only an occasional eosinophilic organelle remnant remaining

97
Q

How does viral-induced hepatocyte death present?

A

lobular architectural disruption, cytolysis, apoptosis, and confulent hepatocyte necrosis

98
Q

What is the genetic mechanism behind high levels of dietary aflatoxin exposure?

A

It is associated with a G:C –> T:A transversion in codon 249 of the p53 gene that increases the risk of hepatocellular carcinoma

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