Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0015695 (fatty liver)
 13,941 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although hepatitis C virus (HCV) is a well-known causative agent of hepatocellular carcinoma (HCC), the mechanism by which HCV induces HCC remains obscure. To elucidate the role of HCV in hepatocarcinogenesis, a model of hepatocyte injury was established using HCV core transgenic mice, which were developed using C57BL/6 mice transfected with the HCV core gene under control of the serum amyloid P component promoter. After 18-24 months, neither steatosis nor hepatic tumors were found in transgenic mice. The extent of hepatocyte injury and tumorigenesis were then examined in transgenic mice following repeated administration of carbon tetrachloride (CCl(4)) using various protocols (20%, 1/week; 10%, 2/week and 20%, 2/week). Serum alanine aminotransferase (ALT) levels did not differ among HCV core transgenic mice and non-transgenic littermates; however, after 40 weeks, hepatic adenomas preferentially developed in transgenic mice receiving 20% CCl(4) once weekly. Moreover, HCC was observed in transgenic mice receiving 2 weekly injections of a 20% solution of CCl(4), and was not observed in the non-transgenic control mice. In conclusion, the HCV core protein did not promote hepatic steatosis or tumor development in the absence of hepatotoxicity. However, the HCV core protein promoted adenoma and HCC development in transgenic mice following repeated CCl(4) administration. These results suggest that hepatotoxicity resulting in an increased rate of hepatocyte regeneration enhances hepatocarcinogenesis in HCV-infected livers. Furthermore, this experimental mouse model provides a valuable method with which to investigate hepatocarcinogenesis.
Cancer Sci 2003 Aug
PMID:Repeated hepatocyte injury promotes hepatic tumorigenesis in hepatitis C virus transgenic mice. 1290 92

In animals, the combination of oxidative liver damage and inhibited hepatocyte proliferation increases the numbers of hepatic progenitors (oval cells). We studied different murine models of fatty liver disease and patients with nonalcoholic fatty liver disease or alcoholic liver disease to determine whether oval cells increase in fatty livers and to clarify the mechanisms for this response. To varying degrees, all mouse models exhibit excessive hepatic mitochondrial production of H(2)O(2), a known inducer of cell-cycle inhibitors. In mice with the greatest H(2)O(2) production, mature hepatocyte proliferation is inhibited most, and the greatest number of oval cells accumulates. These cells differentiate into intermediate hepatocyte-like cells after a regenerative challenge. Hepatic oval cells are also increased significantly in patients with nonalcoholic fatty liver disease and alcoholic liver disease. In humans, fibrosis stage and oval cell numbers, as well as the number of intermediate hepatocyte-like cells, are strongly correlated. However, cirrhosis is not required for oval cell accumulation in either species. Rather, as in mice, progenitor cell activation in human fatty liver diseases is associated with inhibited replication of mature hepatocytes. The activation of progenitor cells during fatty liver disease may increase the risk for hepatocellular cancer, similar to that observed in the Solt-Farber model of hepatocarcinogenesis in rats.
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PMID:Oxidative stress and oval cell accumulation in mice and humans with alcoholic and nonalcoholic fatty liver disease. 1450 39

Increased oxidative stress and lipid peroxidation (LPO) are implicated in multistage carcinogenesis. Recent studies have shown that LPO-derived reactive hydroxyalkenals can form promutagenic exocyclic etheno-DNA adducts in vivo. Such DNA damage was found to be increased in the liver of patients with metal storage diseases and in colon adenomas of familial adenomatous polyposis patients. We now have investigated the levels of 1,N(6)-ethenodeoxyadenosine (epsilon dA) in human liver samples obtained from a group of patients diagnosed with hepatitis, fatty liver, fibrosis and cirrhosis, primary hemochromatosis and Wilson's disease. Using an immunohistochemical method, the relative mean pixel intensity of randomly selected nuclei was measured by imaging software; positively stained cell nuclei (arbitrary mean pixel intensity > or =0.5) were counted. Prevalence of epsilon dA (%) was calculated from the ratio of a number of positively stained cell nuclei over a total number of cells counted. When compared with normal livers (3.1%), the percent prevalence (means) was significantly higher in specimens of alcoholic fatty liver (15%) and fibrosis patients (50%) but not in samples with hepatitis (induced by various factors) (6.2%). The percent prevalence in alcohol fibrosis was as high as in the liver from Wilson's disease (50.7%) and hemochromatosis (33%) patients. This is the first demonstration of increased epsilon dA in human liver diseases due to alcohol abuse. We conclude that excessive hepatic DNA damage, as assessed by miscoding etheno-DNA adduct in the nuclei of liver biopsies, is probably caused by alcohol-induced oxidative stress and LPO. In cancer-prone liver diseases (fatty liver, cirrhosis/fibrosis) such damage may act as a driving force towards malignancy.
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PMID:Immunohistochemical detection of 1,N6-ethenodeoxyadenosine in nuclei of human liver affected by diseases predisposing to hepato-carcinogenesis. 1474 17

The ability of insulin to stimulate glucose disposal varies more than six-fold in apparently healthy individuals. The one third of the population that is most insulin resistant is at greatly increased risk to develop cardiovascular disease (CVD), type 2 diabetes, hypertension, stroke, nonalcoholic fatty liver disease, polycystic ovary disease, and certain forms of cancer. Between 25-35% of the variability in insulin action is related to being overweight. The importance of the adverse effects of excess adiposity is apparent in light of the evidence that more than half of the adult population in the United States is classified as being overweight/obese, as defined by a body mass index greater than 25.0 kg/m(2). The current epidemic of overweight/obesity is most-likely related to a combination of increased caloric intake and decreased energy expenditure. In either instance, the fact that CVD risk is increased as individuals gain weight emphasizes the gravity of the health care dilemma posed by the explosive increase in the prevalence of overweight/obesity in the population at large. Given the enormity of the problem, it is necessary to differentiate between the CVD risk related to obesity per se, as distinct from the fact that the prevalence of insulin resistance and compensatory hyperinsulinemia are increased in overweight/obese individuals. Although the majority of individuals in the general population that can be considered insulin resistant are also overweight/obese, not all overweight/obese persons are insulin resistant. Furthermore, the cluster of abnormalities associated with insulin resistance - namely, glucose intolerance, hyperinsulinemia, dyslipidemia, and elevated plasma C-reactive protein concentrations -- is limited to the subset of overweight/obese individuals that are also insulin resistant. Of greater clinical relevance is the fact that significant improvement in these metabolic abnormalities following weight loss is seen only in the subset of overweight/obese individuals that are also insulin resistant. In view of the large number of overweight/obese subjects at potential risk to be insulin resistant/hyperinsulinemic (and at increased CVD risk), and the difficulty in achieving weight loss, it seems essential to identify those overweight/obese individuals who are also insulin resistant and will benefit the most from weight loss, then target this population for the most-intensive efforts to bring about weight loss.
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PMID:Obesity, insulin resistance, and cardiovascular disease. 1474 3

HIV caregivers face many challenges following initiation of ART. The development of jaundice is uncommon but worrisome. In this case, two distinct and contrasting episodes of jaundice were observed. In the first instance, isolated elevation of the indirect bilirubin without elevation of the alkaline phosphatase was noted. The normal PT and serum aminotransferase levels indicate the absence of intrinsic liver dysfunction. Elevations in the indirect bilirubin may result from either impaired uptake/conjugation or excess production. The latter, usually from acquired hemolysis, may be a complication of an occult NHL. A work-up for this AIDS-related malignancy was not initiated since the caregivers recognized jaundice as a complication of IDV, which inhibits UDP-glucuronyl transferase and produces a Gilbert's-like syndrome. Physicians can expect to encounter this syndrome even more frequently with ATV. Experienced patients given RTV-boosted ATV have experienced elevations of unconjugated hyper-bilirubinemia in up to 45 percent of cases in clinical trials. However, such elevations do not reflect liver dysfunction and symptomatic jaundice requiring dosage reduction that occurred infrequently (7 to 8 percent of study patients). Counseling patients about this syndrome may promote adherence and prevent self-directed interruptions of ATV that compromise efficacy. The second case of jaundice provides a more formidable diagnostic challenge. The triad of LFT abnormalities (mild elevation of aminotransferases, normal PT, and marked cholestatic jaundice) implies an acute process that is mildly toxic to hepatocytes without affecting their synthetic function. The subacute nature of the patient's cholestatic jaundice suggests either intrahepatic infiltrative disease of the liver or extrahepatic obstruction of the biliary tree, most likely due to the patient's relatively modest level of pain and lack of fever. Despite LFT abnormalities occurring 17 months after a switch in his ART, cumulative drug-related toxicities must still be considered. Ritonavir can produce significant elevations in the AST/ALT, especially with pre-existing chronic liver disease as with hepatitis C virus coinfection. The NRTIs can produce hepatic steatosis, a result of mitochondrial toxicity and impaired fatty acid oxidation. However, jaundice and cholestasis are not typical of the latter syndrome. With a negative contrast CT that excludes parenchymal liver disease, investigation of the biliary tree to assess the presence of AIDS-related cholangitis was the next step. Performing a sphincterotomy or stent placement, and obtaining brushings or biopsy specimens to determine the extent of extrahepatic obstruction may help define a pathogen and be life-saving. The negative results of the ERCP justify the final diagnostic step, a liver biopsy to evaluate microscopic infiltrative disease that might not have been detected on contrast abdominal CT. Examples might include granulomatous disease (MAC), fungal etiologies (histoplasmosis), carcinomatosis (lymphoma, hepatoma, cholangiocarcinoma), and microvascular disease (bacillary angiomatosis). The failure to observe granulomatous inflammation in the liver does not exclude MAC infection, as MAC may involve other peri-aortic or mesenteric lymph nodes. This form of IRIS is unlikely given the abdominal CT findings, lack of systemic complaints, and extended persistence of liver aminotransferases. The nonspecific results of the liver biopsy are a common outcome in advanced AIDS patients with elevated alkaline phosphatase levels. Despite not having identified a pathogen, the biopsy establishes chronic liver disease and prompts re-evaluation and change of treatment to NFV. The subsequent normalization of the patient's aminotransferase levels suggests a prior adverse effect of LPV/r in the setting of unexplained, chronic liver disease. Most importantly, this case highlights the importance of HIV caregivers to review ART for safety when noting chronic liver dysfunction. Patients need to be counseled to minimize acetaminophen use, to consume alcohol in moderation, and to avoid behavior with risk for hepatitis C. Finally, all HIV patients should receive appropriate vaccination against hepatitis A and B if serology shows lack of protective immunity.
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PMID:Clinical vignette in antiretroviral therapy: jaundice. 1498 14

Liver fatty acid binding protein is a member of the fatty acid binding group of proteins that are involved in the intracellular transport of bioactive fatty acids and participate in intracellular signalling pathways, cell growth and differentiation. In this study we have used proteomics and immunohistochemistry to determine the changes in liver fatty acid binding protein in colorectal neoplasia. Comparative proteome analysis of paired samples colorectal cancer and normal colon identified consistent loss of liver fatty acid binding protein (L-FABP) in colorectal cancer compared with normal colon. To identify the changes in liver fatty acid binding protein expression during colorectal cancer development and progression the cell-specific expression of L-FABP was determined by immunohistochemistry in a series of colorectal cancers and colorectal adenomas. Decreased L-FABP immunoreactivity was significantly associated with poorly differentiated cancers (P<0.001). In colorectal adenomas there was a significant trend towards decreased staining of L-FABP in the larger adenomas (P<0.001). There was consistent L-FABP immunostaining of normal surface colonocytes. This study demonstrates that loss of L-FABP occurs at the adenoma stage of colorectal tumour development and also indicates that L-FABP is a marker of colorectal cancer differentiation.
Br J Cancer 2004 May 17
PMID:Liver fatty acid binding protein expression in colorectal neoplasia. 1513 77

Mitochondrial generation of reactive oxygen species (ROS) is increased in mice with fatty livers induced by genetic obesity, chronic consumption of ethanol, or methionine/choline-deficient diets. Both nuclear and mitochondrial (mt) DNA are targets for ROS-induced damage and accumulate hydroxylated bases, such as 8-hydroxy-2'-deoxyguanosine (8-oxoG) and base substitution of adenine with 8-oxoG (A*8-oxoG), that introduce mutations that promote cancer as well as cell death. The mammalian homolog of the bacterial DNA mismatch repair enzyme MutY (MYH) removes A*8-oxoG from nuclear and mtDNA, reduces 8-oxoG accumulation, and restores genomic stability after ROS exposure. Cumulative damage to mtDNA occurs as fatty liver disease progresses. Therefore, differences in hepatic MYH activity may influence the severity of fatty liver disease. To evaluate this hypothesis, we compared mtH2O2 production, MYH expression, oxidative DNA damage, and hepatocyte death in healthy mice and different mouse models of fatty liver disease. The results show that diverse causes of steatohepatitis increase mtROS production, limit repair of mtDNA, and oxidatively damage DNA. However, there are important differences in the DNA repair response to oxidant stress among mouse models of fatty liver disease. Independent of the degree of mtROS generation, models with the least MYH exhibit the greatest accumulation of 8-oxoG and the most hepatocyte death. These findings raise the intriguing possibility that inherited or acquired differences in DNA repair enzyme activity may underlie some of the interindividual differences in fatty liver disease outcomes.
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PMID:Oxidative DNA damage and DNA repair enzyme expression are inversely related in murine models of fatty liver disease. 1523 85

Epidemiological studies have shown that obesity is a risk factor for hepatocellular carcinoma. Similar studies further indicate that diabetes is also a major risk factor. Both obesity and diabetes are frequently associated with nonalcoholic fatty liver disease, and case reports have shown progression of nonalcoholic fatty liver disease to cirrhosis and hepatocellular carcinoma. Although no study has clearly tied all of these variables together, it is likely that the association of hepatocellular carcinoma with obesity represents the progression of underlying nonalcoholic fatty liver disease to cirrhosis. The mechanism most likely involves replicative senescence of steatotic mature hepatocytes and compensatory hyperplasia of progenitor (oval) cells as a reaction to chronic injury due to ongoing nonalcoholic steatohepatitis and resultant hepatic fibrosis. Growth factors associated with chronic inflammation, type 2 diabetes, and DNA mutations as a result of lipid peroxidation probably play significant roles in clonal expansion and hepatocellular carcinoma progression. It remains unclear whether cirrhosis is a prerequisite for the development of hepatocellular carcinoma or whether hepatocellular carcinoma can develop in fatty liver in the absence of cirrhosis. However, well-documented case reports suggest that most cases of hepatocellular carcinoma arise in the setting of nonalcoholic steatohepatitis with cirrhosis. Whether therapy aimed at nonalcoholic fatty liver disease reduces the risk of hepatocellular carcinoma remains to be shown. Prophylactic measures and the role of cancer surveillance have not been adequately investigated, but current evidence suggests a risk for hepatocellular carcinoma in nonalcoholic steatohepatitis-related cirrhosis that rivals that of hepatocellular carcinoma in hepatitis C virus-related cirrhosis, particularly in older male patients.
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PMID:Obesity and hepatocellular carcinoma. 1550 9

DNA methylation is an important epigenetic mechanism of transcriptional control. DNA methylation plays an essential role in maintaining cellular function, and changes in methylation patterns may contribute to the development of cancer. Aberrant methylation of DNA (global hypomethylation accompanied by region-specific hypermethylation) is frequently found in tumor cells. Global hypomethylation can result in chromosome instability, and hypermethylation has been associated with the inaction of tumor suppressor genes. Preclinical and clinical studies suggest that part of the cancer-protective effects associated with several bioactive food components may relate to DNA methylation patterns. Dietary factors that are involved in one-carbon metabolism provide the most compelling data for the interaction of nutrients and DNA methylation because they influence the supply of methyl groups, and therefore the biochemical pathways of methylation processes. These nutrients include folate, vitamin B(12), vitamin B(6), methionine, and choline. However, looking at individual nutrients may be too simplistic. Dietary methyl (folate, choline, and methionine) deficiency in combination causes decreased tissue S-adeno-sylmethionine, global DNA hypomethylation, hepatic steatosis, cirrhosis, and ultimately hepatic tumorigenesis in rodents in the absence of carcinogen treatment. Other dietary components such as vitamin B(12), alcohol, and selenium may modify the response to inadequate dietary folate.
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PMID:DNA methylation, cancer susceptibility, and nutrient interactions. 1552 34

Obesity has reached epidemic levels in industrialized countries and is increasing worldwide. This trend has serious public health consequences, since obesity increases the risk of diabetes, hypertension, heart disease, sleep apnea, cancer, arthritis, cholelithiasis, fatty liver disease, and other complications. Obesity is the result of an imbalance between energy intake and expenditure; hence, an understanding of how gastrointestinal function is integrated with the hormonal regulation of energy balance is pertinent to the pathophysiology of obesity. Nutrients, peptides, and neural afferents from the gut influence the size and frequency of meals and satiety. The long-term regulation of energy stores is mediated primarily through the actions of adiposity hormones, such as leptin and insulin, in the hypothalamus and other neuronal circuits in the brain. Efforts are underway to determine how these peripheral and central pathways may be targeted for treatment of obesity and related diseases.
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PMID:Gut peptides and other regulators in obesity. 1560 2


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