Chapter 18: Liver Diseases Flashcards
Regeneration of the liver occurs via 2 major mechanims, which are?
1) Proliferation of remaining hepatocytes
2) Repopulation from progenitor cells
Describe the priming, growth factor, and termination phases of hepatocyte proliferation in the regenerating liver?
1) Priming - IL-6 produced by Kupffer cells act on hepatocytes making parenchymal cells competent to receive/respond to GF signals
2) GF phase - factos such as HGF and TGF-α act on primed hepatocytes to stimulate cell metabolism and entrance into cell cycle
3) Termination - hepatocytes return tp quiescence
Which 3 serum enzyme measurements represent a response to disrupted hepatocyte integrity?
- ALT
- AST
- LDH
Serum measurements of which 2 enzymes look for damage to bile canaliculus?
- Serum alkaline phosphatase
- Serum γ-glutamyl transpeptidase (GGT)
Which 2 serum measurements assess hepatocyte metabolism; which is increased in liver disease and which is decreased?
- Serum ammonia –> increased in L.D.
- Aminopyrine breath test (hepatic demethylation) –> decreased in L.D.
Accumulation of fat (steatosis) and bilirubin (cholestasis) in hepatocytes represent _________ (reversible/irreversible) changes
Reversible
What is the predominant mode of hepatocyte death seen in ischemic/hypoxic injury and is a significant part of oxidative stress?
Necrosis
Which cells cluster at sites of hepatocyte injury and mark sites of hepatocyte necrosis?
Macrophages
Councilman bodies are the apoptotic bodies associated with what disease?
Yellow fever
What is the name of the apoptotic bodies seen in diseases such as acute and chronic hepatitis?
Acidophil bodies –> deeply eosinophilic staining
Is stem cell replenishment a significant part of parenchymal repair during hepatocyte regeneration?
- NO
- Hepatocytes are almost stem-cell like in their ability to continue to replicate even in the setting of years of chronic injury
Eventually, in chronic disease the hepatocytes reach replicative capacity (senesence) and stem cell activation occurs in the form of which reaction?
Ductular reactions
What is the principal liver cell type involved in scar deposition?
Hepatic stellate cell
The expression of which receptor by hepatic stellate cells is one of the initial changes during their activation into myofibroblasts?
PDGFR-β
What is seen encircling the surviving, regenerating hepatocytes in the late stages of chronic liver disease and give rise to the diffuse scarring described as cirrhosis?
Fibrous septa
Stellate cells transform into myofibroblasts that when stimulated by ________ can contract
Endothelin-1 (ET-1)
Chemotaxis of activated stellate cells to areas of injury are promoted by which factors?
- PDGF
- Monocyte chemotactic protein-1 (MCP-1)
If the chronic liver injury leading to scar formation is interrupted (i.e., clearance of hepatitis virus infection, cessation of alcohol use), which events occur leading to reversal of scar formation?
Which factor breaks the scars apart?
- Stellate cells stop being activated
- Scars condense –> become more dense and thin
- Metalloproteinases produced by hepatocytes break the scar apart
Acute liver failure (aka fulminant liver failure) is defined as occuring within what time period?
Associated disorders?
Pre-existing liver dysf.?
- Occurs within 26 weeks (6 months) of the initial liver injury
- Associated w/ encephalopathy and coagulopathy
- Absence of pre-existing liver disease
Acute live failure is caused by what type of tisuse injury?
Massive hepatic necrosis
What is the major cause of acute liver failure in the US?
What accounts for the rest of cases?
- Accidental or deliberate OD of Acetaminophen (major cause)
- Autoimmune hepatitis
- Other drugs/toxins
- Acute hepatitis A and B infections
With acetaminophen toxicity, how quicly does the liver failure occur?
Within one week of the onset of sx’s
In chronic inflammation which inflammatory cytokines are produced which act as stimuli for Stellate Cell activation?
- TNF
- Lymphotoxin
- IL-1β
What % of hepatic functional capacity must be lost before hepatic failure ensues?
80-90%
How is the morphology of acute liver failure different in toxic injuries (i.e., acetaminophen) vs. that caused by viral injuries?
Toxic = NO scarring/regeneration due to rapid onset of injury
Viral = scarring and regeneration occur due to slower progression
Diffuse poisoning of liver cells w/o obvious cell death and parenchymal collapse = diffuse microvesicular steatosis, and is usually related to dysfunction of what?
Seen in what settings?
- Mitochondrial dysfunction
- Fatty liver of pregnancy or idiosyncratic rxns to toxins (i.e., valproate or tetracyclin)
Which 3 viruses are most often the cause of fulminant liver failure in the setting of immunodeficiency?
- CMV
- Herpes simplex
- Adenovirus
What is a characteristic sign of Hepatic Encephalopathy?
How does it present?
- Asterixis = nonrhythmic, rapid extension-flexion movements of head and extremities
- Best seen w/ arms held in extension w/ dorsiflexed wrists
Hepatic encephalopathy seen in acute liver failue is due to elevated serum levels of?
Ammonia
Which disorders of coagulopathy may be seen in acute liver failure?
Earliest sign?
- Easy bruising = earliest sign –> can lead to fatal intracranial bleeds
- Liver also removes activated coagulation factors from circulation, and loss of this function –> Disseminated intravascular coagulation
Portal HTN is more common in chronic liver failure, but if it occurs in acute liver failure what are the major clinical consequences?
Where is the obstruction in this setting?
- Extrahepatic obstruction
- Ascites and hepatic encephalopathy
What are the main renal functional abnormalities which are seen in Hepatorenal Syndrome associated w/ Acute Liver Failure?
The syndrome’s onset begins with a drop in what and rising?
- Na+ retention
- Impaired free-water excretion
- Decreased renal perfusion and GFR
*Begins w/ a drop in urine output + rising BUN and creatinine
Diffuse transformation of entire liver into regenerative parenchymal NODULES surrounded by fibrous bands and variable degress of vascular (often portosystemic) shunting describes what?
Cirrhosis
What is the utility of the Child-Pugh classification of cirrhosis?
Helps monitor the decline of patients on the path to chronic liver failure
*Class A (well compensated); Class B (partial comp.); Class C (decompensated)*
How does the progression of chronic liver disease correlate with ductular reactions and when are these rxns most prominent?
- Ductular rxns increase w/ advancing stage of disease
- Most prominent in cirrhosis
The morphology of broad bands of fibrous dense scar, often w/ dilated lymphatic spaces, with less intervening parenchyma is related to the prognosis of chronic liver disease how?
- More likely to progress to portal HTN
- End-stage disease
What is the significance of this photo and to our understanding of the cirrhotic liver?
- Image on left is an active drinker, while the one on the right is after following long-term abstinence
- Shows that regression of fibrosis CAN take place!
How does the jaundice associated w/ chronic liver disease differ from that of acute?
How severe can it get and what is the treatment at the most severe stages?
- Associated w/ pruritus –> itching which can be very intense
- Pt may scratch their skin raw and liver transplantation may be the only relief!
What are the adverse effects of impaired estrogen metabolism and consequent hyperestrogenemia associated w/ chronic liver disease?
- Palmar erythema
- Spider angiomas
- Hypogonadism and Gynecomastia in males
What are 4 of the most clinically significant findings of portal HTN in the setting of cirrhosis?
- Hepatic encephalopathy
- Esophageal varices
- Splenomegaly
- Ascites
What is the dominant intrahepatic cause of portal HTN?
Cirrhosis
What is the morphology of the fluid seen in ascites, composed of?
- Serous fluid w/ <3 g/dL of protein (largely albumin)
- Scant # of mesothelial cells and mononuclear leukocytes
What is a significant consequence which may arise from long-standing ascites?
Seepage of peritoneal fluid thru trans-diaphragmatic lymph producing a hydro-thorax, most often on the RIGHT
What are the 3 mechanism which account for the pathogenesis of ascites?
- Sinusoidal HTN promoted by hypoalbuminemia
- Percolation of hepatic lymph into the peritoneal cavity
- Splanchnic vasodilation and hyperdynamic circulation
What is responsible for massive hematemesis and death in pts with advanced cirrhosis of the liver?
Esophageal varices
Massive splenomegaly associated w/ portal HTN may secondarily induce what hematologic abnormalities?
- Thrombocytopenia –> low platelet count
- Pancytopenia –> low red and white cells + platelets
What is the pathogenesis of Hepatopulmonary Syndrome associated w/ cirrhosis of the liver and portal HTN?
Intrapulmonary vascular dilations –> ↑ blood flow –> ↓ O2 diffusion of blood —> hypoxia (dyspnea that is worse when standing)
Pts experiencing Hepatopulmonary Syndrome will have what symptom?
Dyspnea exacerbated in an upright position
*Poorer prognosis
What are the 2 most common clinical manifestations of Portopulmonary HTN?
1) Dyspnea on exertion
2) Clubbing of the fingers
Which viral hepatitis does NOT cause chronic hepatitis or a carrier state?
Hepatitis A
Which family does Hep A belong to?
DNA or RNA virus?
Enveloped or non-enveloped?
- Picornavirus family
- small, nonenveloped, (+)-strand RNA virus
How is Hep A typically spread?
- Ingestion of contaminated food/water
- Fecal-oral
What is a common cause of sporadic infection and source of outbreaks of Hepatitis A in developed countries?
- Consumption of raw or steamed shellfish, which concentrate the virus from seawater contaminated by human sewage
- Works in food industry may also be a source of outbreaks
Which immune cell appears to play the key role in the hepatocellular injury caused during Hep A and B infection?
CD8+ cytotoxic T cells
Which antibodies against HAV appear with onset of symptoms?
Followed by the appearance of which antibodies, conferring lifelong immunity?
- IgM anti-HAV appear at onset of sx’s
- IgG anti-HAV appear later and confer immunity
Even in the absence of cirrhosis, chronic infection by which hepatitis virus is an important precursor for the development of hepatocellular carcinoma?
Hepatitis B
In high prevalence areas of HBV what is the major mode of transmission?
Transmission during childbirth
What is the most common mode of transmission for HBV in areas with intermediate prevalence and areas with low prevalence?
- Intermediate - horizontal transmission in early childhood, thru minor breaks in skin or mucous membranes
- Low - unprotected sex and IV drug abuse (sharing needles)
Which virus family is HBV a part of?
Describe its morphology (RNA/DNA, envelope, shape)
- Hepadnaviridae fam
- Enveloped, PARTIALLY double-stranded circular DNA
How is the diagnosis of Hepatitis A made?
Detection of serum IgM Abs
What is unique about the replication cycle of HBV?
Mediated by what?
- Contains Pol, which exhibits both DNA polymerase and reverse transcriptase activity
- DNA —> RNA —> DNA
Which “core” protein of HBV stays within hepatocytes and participates in the assembly of complete virions?
HBcAg
Which mature hepatitis virus, when intact, is referred to as the “Dane particle?”
HBV
What can be used for the diagnosis of HBV infection?
- Detection of HBsAg or anti-HBcAg Abs
- PCR for HBV DNA
Which viral antigen associated w/ HBV appears in the blood before the onset of symptoms?
What does the presence of this Ag indicate?
- HBsAg
- Means there is a LIVE virus and infection, either acute, chronic, or carrier
Presence of which antibodies against viral Ags of HBV are indicative of immunity, cure, or no active disease?
Anti-HBsAg –> may persist for life, conferring protection
Persistence of what viral Ag in HBV infection is an important indicator of continued viral replication, infectivity, and probable progression to chronic hepatitis?
HBeAg
Which immunoglobulin is indicative of acute HBV infection and which is indicative of chronic or resolving infection?
- IgM anti-HBcAg = new infection; acute infection
- IgG anti-HBcAg = old infection; chronic infection
What is the best predictor of chronicity in association with HBV infection?
Age at the time of infection
*Younger the age = higher probability of chronicity