法尼醇类受体基因在胆囊中的表达

目的:探讨法尼醇类受体基因(FXR)的表达与胆囊的关系。方法:采用含17000cDNA克隆的基因微矩阵,与2例正常胆囊之cDNA杂交,发现FXR基因信号后,进一步进行RT-PCR和测序验证。结果:基因芯片能够检测出FXR在正常胆囊中的表达,其平均灰度值为16.80。在进一步的RT-PCR实验中,扩增出FXR的特异性片段,为352碱基。该PCR片段经测序后,其结果在GENEBANK数据库经BLAST比对,证实其同源性与FXR一致。结论:FXR在胆囊中表达,提示该基因可能还有新的未知功能。     

Bile Acids Induce Cdx2 Expression Through the Farnesoid X Receptor in Gastric Epithelial Cells

Clinical and experimental studies showed that the reflux of bile into the stomach contributes to the induction of intestinal metaplasia of the stomach and gastric carcinogenesis. Caudal-type homeobox 2 (Cdx2) plays a key role in the exhibition of intestinal phenotypes by regulating the expression of intestine-specific genes such as goblet-specific gene mucin 2 (MUC2). We investigated the involvement of the farnesoid X receptor (FXR), a nuclear receptor for bile acids, in the chenodeoxycholic acid (CDCA)-induced expression of Cdx2 and MUC2 in normal rat gastric epithelial cells (RGM-1 cells). RGM-1 cells were treated with CDCA or GW4064, an FXR agonist, in the presence or absence of guggulsterone, an FXR antagonist. CDCA induced dose-dependent expression of Cdx2 and MUC2 at both the mRNA and protein levels. The maximum stimulation of Cdx2 and MUC2 mRNA induced by CDCA was observed at 3 h and by 6 h, respectively. GW4064 also induced expression of these molecules. The effects of CDCA and GW4064 on expression of Cdx2 and MUC2 were abolished by guggulsterone. These findings suggest that bile acids may induce gastric intestinal metaplasia and carcinogenesis through the FXR.     

Farnesoid X receptor is essential for normal glucose homeostasis

The bile acid receptor farnesoid X receptor (FXR; NR1H4) is a central regulator of bile acid and lipid metabolism. We show here that FXR plays a key regulatory role in glucose homeostasis. FXR-null mice developed severe fatty liver and elevated circulating FFAs, which was associated with elevated serum glucose and impaired glucose and insulin tolerance. Their insulin resistance was confirmed by the hyperinsulinemic euglycemic clamp, which showed attenuated inhibition of hepatic glucose production by insulin and reduced peripheral glucose disposal. In FXR-/- skeletal muscle and liver, multiple steps in the insulin signaling pathway were markedly blunted. In skeletal muscle, which does not express FXR, triglyceride and FFA levels were increased, and we propose that their inhibitory effects account for insulin resistance in that tissue. In contrast to the results in FXR-/- mice, bile acid activation of FXR in WT mice repressed expression of gluconeogenic genes and decreased serum glucose. The absence of this repression in both FXR-/- and small heterodimer partner-null (SHP-/-) mice demonstrated that the previously described FXR-SHP nuclear receptor cascade also targets glucose metabolism. Taken together, our results identify a link between lipid and glucose metabolism mediated by the FXR-SHP cascade.     

法尼酯X受体与肠道疾病的关系

法尼酯X受体(FXR)是胆汁酸的生理性受体,可以感知细胞内胆汁酸水平,是调节胆汁酸代谢及转运的关键物质。研究FXR与肠道疾病的关系,有助于进一步了解FXR的作用机制,为早期发现和治疗肠道疾病提供新靶点。     

Targeting Complement C5a Receptor 1 for the Treatment of Immunosuppression in Sepsis

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Quality Improvement Targeting Early Phase of Hepatitis C Care Delivery

Liver fibrosis evaluation is one of the most important assessments in patients with chronic hepatitis C. In an inner-city infectious disease clinic, more than 30% of patients with hepatitis C did not have complete evaluation for liver fibrosis, potentially leading to negative clinical outcomes. A quality improvement project was developed to improve and standardize liver fibrosis evaluation through the implementation of an order set in the electronic medical record. The implementation of the electronic order set was effective in improving the fibrosis evaluation completion rate by more than 20% (P = 0.016).     

Identification of Hepatitis C Virus Inhibitors Targeting Different Aspects of Infection Using a Cell-Based Assay

With 2 to 3% of the worldwide population chronically infected, hepatitis C virus (HCV) infection continues to be a major health care burden. Unfortunately, current interferon-based treatment options are not effective in all patients and are associated with significant side effects. Consequently, there is an ongoing need to identify and develop new anti-HCV therapies. Toward this goal, we previously developed a cell-based HCV infection assay for antiviral compound screening based on a low-multiplicity-of-infection approach that uniquely allows for the identification of antiviral compounds that target cell culture-derived HCV (HCVcc) at any step of the viral infection cycle. Using this assay, here we report the screening of the NCI Diversity Set II library, containing 1,974 synthesized chemical compounds, and the identification of compounds with specific anti-HCV activity. In combination with toxicity counterscreening, we identified 30 hits from the compound library, 13 of which showed reproducible and dose-dependent inhibition of HCV with mean therapeutic indices (50% cytotoxic concentration [CC₅₀]/50% effective concentration [EC₅₀]) of greater than 6. Using HCV pseudotype and replicon systems of multiple HCV genotypes, as well as infectious HCVcc-based assembly and secretion analysis, we determined that different compounds within this group of candidate inhibitors target different steps of viral infection. The compounds identified not only will serve as biological probes to study and further dissect the biology of viral infection but also should facilitate the development of new anti-HCV therapeutic treatments.     

Hepatitis C infection: a clinical review

Nearly three million persons in the United States are viremic with hepatitis C (HCV). Despite a decreasing incidence of HCV in this country, the prevalence of HCV-related chronic liver disease is increasing. Most infections in the United States are acquired by intravenous drug use. The chronicity rate of HCV is high, reaching 85% in some populations, and the risk of progression to advanced liver disease is as high as 20% within twenty years of infection. Host factors like alcohol use accelerate the rate of progression. The enzyme immunoassay is the preferred initial test for diagnosis; the third generation assay has greater than a 99% specificity in immunocompetent patients. Barring contraindications, the standard of care for treatment of chronic HCV has become pegylated interferon and ribavirin. With this therapy, the cure rate for treatment-na?ve patients is about 55%, but rates are higher in certain groups. Common side effects of therapy include neuropsychiatric symptoms, influenza-like symptoms and hematological abnormalities.     

Hepatitis C: a danger to healthcare workers

There is no vaccine to prevent hepatitis C. The disease has infected more than 4 million people in the United States. Up to 10,000 people in the United States will die annually from the disease and that number will triple by the year 2010 (more than AIDS) (National Institutes of Health, 1997). The primary transmission route is through blood. The risk to healthcare workers of becoming infected after exposure from a needle stick is between 1.2% to 10%, whereas for HIV it is 0.3%. Healthcare workers must shift their self-protection focus from HIV to hepatitis C. Annual education on Universal Precautions must emphasize the risk of hepatitis C. Further, all healthcare workers should be baseline-tested immediately following exposure.     

Farnesoid X receptor deficiency induces nonalcoholic steatohepatitis in low-density lipoprotein receptor-knockout mice fed a high-fat diet

Nonalcoholic steatohepatitis (NASH) comprises dysregulation of lipid metabolism and inflammation. Identification of the various genetic and environmental susceptibility factors for NASH may provide novel treatments to limit inflammation and fibrosis in patients. This study utilized a mouse model of hypercholesterolemia, low-density lipoprotein receptor knockout (LDLr(-/-)) mice fed a high-fat diet for 5 months, to test the hypothesis that farnesoid X receptor (FXR) deficiency contributed to NASH development. Either the high-fat diet or FXR deficiency increased serum alanine aminotransferase activity, whereas only FXR deficiency increased bile acid and alkaline phosphatase levels. FXR deficiency and high-fat feeding increased serum cholesterol and triglycerides. Although high fat led to macrosteatosis and hepatocyte ballooning in livers of mice regardless of genotype, no inflammatory infiltrate was observed in the livers of LDLr(-/-) mice. In contrast, in the livers of LDLr(-/-)/FXR(-/-) mice, foci of inflammatory cells were observed occasionally when fed the control diet and were greatly increased when fed the high-fat diet. Consistent with enhanced inflammatory cells, hepatic levels of tumor necrosis factor alpha and intercellular adhesion molecule-1 mRNA were increased by the high-fat diet in LDLr(-/-)/FXR(-/-) mice. In agreement with elevated levels of procollagen 1 alpha 1 and TGF-beta mRNA, type 1 collagen protein levels were increased in livers of LDLr(-/-)/FXR(-/-) mice fed a high-fat diet. In conclusion, FXR deficiency induces pathologic manifestations required for NASH diagnosis in a mouse model of hypercholesterolemia, including macrosteatosis, hepatocyte ballooning, and inflammation, which suggest a combination of FXR deficiency and high-fat diet is a risk factor for NASH development, and activation of FXR may be a therapeutic intervention in the treatment of NASH.     

Zinc-finger Nucleases as a Novel Therapeutic Strategy for Targeting Hepatitis B Virus DNAs

Hepatitis B virus (HBV) chronically infects 350–400 million people worldwide and causes >1 million deaths yearly. Current therapies prevent new viral genome formation, but do not target pre-existing viral genomic DNA, thus curing only ~1/2 of patients. We targeted HBV DNA for cleavage using zinc-finger nucleases (ZFNs), which cleave as dimers. Co-transfection of our ZFN pair with a target plasmid containing the HBV genome resulted in specific cleavage. After 3 days in culture, 26% of the target remained linear, whereas ~10% was cleaved and misjoined tail-to-tail. Notably, ZFN treatment decreased levels of the hepatitis C virus pregenomic RNA by 29%. A portion of cleaved plasmids are repaired in cells, often with deletions and insertions. To track misrepair, we introduced an XbaI restriction site in the spacer between the ZFN sites. Targeted cleavage and misrepair destroys the XbaI site. After 3 days in culture, ~6% of plasmids were XbaI-resistant. Thirteen of 16 clones sequenced contained frameshift mutations that would lead to truncations of the viral core protein. These results demonstrate, for the first time, the possibility of targeting episomal viral DNA genomes using ZFNs.     

Hepatitis C: Implications for the general physician

Approximately 4 million people in the United States are affected with chronic hepatitis C--20%-25% of whom will develop cirrhosis. Determination of the stage of disease and extent of cirrhosis requires liver biopsy. In cirrhotic patients, regular screening for hepatocellular carcinoma is indicated.     

Hepatitis C: treatment challenges

Hepatitis C is a significant public health problem, yet transmission can be prevented and the disease is treatable. Nurses have a key role in delivering care.     

输血后HCV感染的前瞻性研究

目的：了解上海地区医院内输血后丙型肝炎病毒（HCV）感染的现状，以制定相应的防治策略。方法：对输血的本院内、外科住院病人采用前瞻性调查。结果：输血后HCV感染率可高达8．48％，而同期住院未输血的对照组未发现HCV感染，而且HCV感染率随输血量增加而呈上升趋势；加强输血前筛查的方法可使感染率降至2．1％左右。结论：在尚无丙型肝炎疫苗的情况下，提倡义务献血和加强对血源的筛查是控制输血后肝炎的有效和必要的措施。     

Hepatitis C Lookback Programme: a single hospital experience

As part of the national Hepatitis C (HCV) Lookback Programme, HCV-infected donors donating blood after September 1991 were identified and the fate of their previous donations received at a single hospital were traced; 123 of 160 implicated blood components were traceable and transfused. Only 19 recipients were alive and traceable and were tested for HCV. Nine of the 14 recipients (64%) of HCV-positive donations and 2 of 5 recipients (40%) of HCV-indeterminate donations had evidence of HCV infection. Neither the number of donor exposures nor the type of component was predictive of recipient HCV status. Three recipients have chronic active hepatitis. The Hepatitis C Lookback Programme successfully identifies some but not all cases of transfusion-transmitted HCV. Transfusion records, particularly in the medical case notes, should be substantially improved. Many of the traced recipients are young, so that identification of HCV is of great importance.     

Hepatitis C: a public health response in Kansas

The hepatitis C (HCV) infection prevalence in Kansas is concentrated in populations with increased risk factors for acquiring the virus. Testing the appropriate population and providing counseling and medical referral to these high risk individuals is accomplished by offering HCV testing at HIV Counseling and Testing sites across the state. Such public health programs along with the medical community allow the at risk populations of Kansas an opportunity to improve their health and decrease the spread of HCV