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Biomedical subjects

A J Sanyal

Publications and source records attributed to A J Sanyal.

At least 19 recordsLinked to original sources
PubMed2005

Insulin resistance in NASH.

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease observed in the clinical practice of hepatology. The coexistence of metabolic syndrome in this cohort of patients has made insulin resistance central to the pathogenesis of these disorders. The metabolic consequence of insulin resistance is impaired hepatic glucose output and abnormal lipid handling. In the face of continued metabolic insults the normal hepatic regulatory mechanism gets overwhelmed and fat accumulates in the hepatocytes. The subsequent fate of steatotic hepatocytes depends on the capacity of additional factors such as adipocytokines and toxicity induced by the free fatty acids themselves to induce inflammatory response. This latter process is responsible for the producing the phenotype of non-alcoholic steatohepatitis (NASH). Irrespective of the process by which these phenotypic response occurs, it is now universally accepted that in the absence of insulin resistance the spectrum of changes one associates with NAFLD does not develop. In this review we will discuss the various processes that are involved in the pathogenesis of NAFLD.

Fatty Liver↗
PubMed2005

Review article: non-alcoholic fatty liver disease and hepatitis C--risk factors and clinical implications.

Hepatitis C and non-alcoholic fatty liver disease (NAFLD) are the two most common liver diseases in the Western hemisphere. It is therefore natural that these conditions often co-exist in the same individual. Hepatitis C, especially genotype 3, is often associated with hepatic steatosis. In subjects with genotype 3 infection, a sustained virologic response to treatment is associated with improvement in hepatic steatosis. The diagnosis of NAFLD in a subject with hepatitis C infection is based on the presence of hepatic steatosis. Most investigators require the presence of at least grade II steatosis to warrant a diagnosis of concomitant NAFLD because the significance of minimal steatosis is uncertain. The presence of steatohepatitis is surmised by the additional presence of Mallory bodies, cytologic ballooning and pericellular fibrosis. It is of paramount importance to exclude alcohol as a cause of these histologic findings in this population before a diagnosis of NAFLD is made. The presence of NAFLD in subjects with hepatitis C genotype 1 infection is most strongly associated with the presence of the metabolic syndrome and insulin resistance. The degree of hepatic steatosis correlates with the degree of hepatic fibrosis and the presence of concomitant steatosis is associated with more advanced fibrosis. The presence of cytologic ballooning confers an additional risk for increased fibrosis. Insulin resistance and hyperinsulinemia have been associated with increased collagen production by hepatic stellate cells. Subjects with hepatitis C and NAFLD are more likely to be virologic nonresponders following anti-HCV therapy. The value of treating insulin resistance and NAFLD prior to antiviral therapy remains to be experimentally verified.

Antiviral Agents↗
PubMed2004

A prospective, randomized-controlled pilot study of ursodeoxycholic acid combined with mycophenolate mofetil in the treatment of primary sclerosing cholangitis.

BACKGROUND: Ursodeoxycholic acid has been ineffective in the treatment of primary sclerosing cholangitis. Because the pathogenesis of primary sclerosing cholangitis is related to immune destruction of bile duct epithelium, several immune suppressive agents have been evaluated. Mycophenolate mofetil is a potent immunosuppressant that is now widely used in organ transplantation. AIM: In this pilot study to determine if mycophenolate mofetil when combined with ursodeoxycholic acid could prevent evidence of clinical progression and improve the biochemical, histological and/or cholangiographic features of primary sclerosing cholangitis compared with patients treated with ursodeoxycholic acid alone. METHODS: Twenty-five patients with well-defined primary sclerosing cholangitis were randomized to ursodeoxycholic acid (13-15 mg/kg/day) with or without mycophenolate mofetil (1000 mg b.d.). Cholangiography and liver biopsy were performed at study entry and after 2 years of treatment. Symptoms, clinical features of liver disease and biochemical tests were monitored at 3-month intervals. RESULTS: The mean age 44 years, 58% male, 84% Caucasian and 64% had ulcerative colitis. After 2 years, there were no differences in laboratory values, histological stage or cholangiograms between patients treated with ursodeoxycholic acid alone and those treated with mycophenolate mofetil + ursodeoxycholic acid. CONCLUSIONS: Mycophenolate mofetil combined with ursodeoxycholic acid does not appear to provide additional benefit compared with standard doses of ursodeoxycholic acid alone in the treatment of primary sclerosing cholangitis.

Adult↗
PubMed2001

A randomized, controlled trial to determine whether continued ribavirin monotherapy in hepatitis C virus-infected patients who responded to interferon-ribavirin combination therapy will enhance sustained virologic response.

This study assessed the use of ribavirin monotherapy to enhance sustained virologic response in hepatitis C virus (HCV)-infected patients who achieved virologic response to interferon (IFN)-ribavirin combination therapy. Patients who had chronic HCV infection and prior relapse were retreated with IFN-ribavirin for 6 months. Patients with an end-of-treatment virologic response were assigned randomly to either stop use of both IFN and ribavirin or to continue use of ribavirin as monotherapy for an additional 6 months. HCV RNA became undetectable during treatment in 46 patients, who then entered the randomized trial. Sustained virologic response was observed in 13 of 26 patients who continued ribavirin monotherapy and in 15 of 20 patients who stopped use of both IFN and ribavirin (P, not significant). Sustained virologic response was significantly more common in patients with HCV genotype non-1 (75% vs. 56%) and in patients with a virus titer < 2 x 10(6) copies/mL (93% vs. 43%). The results indicate that continuing ribavirin monotherapy after achieving a virologic response does not improve sustained virologic response.

Adult↗
PubMed2001

Portal hypertension.

Many advances in the management of portal hypertension and variceal hemorrhage have occurred during the last 10 years. Effective therapy for primary prevention of variceal hemorrhage is now available in the form of nonselective beta-blockers. Active bleeding should be managed with terlipressin, somatostatin or its analogues, and endoscopic therapy; TIPS and surgery are reserved as salvage therapy for patients who fail endoscopic treatment. Survivors of a variceal hemorrhage should be evaluated for liver transplantation. Specific treatment may be provided with EVL while these patients await transplantation. Patients who fail endoscopic treatment may be treated by TIPS or surgery.

Endoscopy, Digestive System↗
PubMed2001

Laboratory assessment of hepatic hemodynamics.

Although the study of hepatic circulation is complicated by the dual blood supply and complex anatomy of the liver, many distinct methods are available to facilitate its study. Before embarking on an investigation of hepatic hemodynamics, the investigator must be familiar with the available methods and their applications. All methods have their own attributes and limitations. No one method is superior to the others, but, depending on the aspect of hepatic hemodynamics to be investigated, a particular methodology may yield distinct advantages.

Animals↗
PubMed2001

Endocannabinoids acting at vascular CB1 receptors mediate the vasodilated state in advanced liver cirrhosis.

Advanced cirrhosis is associated with generalized vasodilation of unknown origin, which contributes to mortality. Cirrhotic patients are endotoxemic, and activation of vascular cannabinoid CB1 receptors has been implicated in endotoxin-induced hypotension. Here we show that rats with biliary cirrhosis have low blood pressure, which is elevated by the CB1 receptor antagonist SR141716A. The low blood pressure of rats with CCl4-induced cirrhosis was similarly reversed by SR141716A, which also reduced the elevated mesenteric blood flow and portal pressure. Monocytes from cirrhotic but not control patients or rats elicited SR141716A-sensitive hypotension in normal recipient rats and showed significantly elevated levels of anandamide. Compared with non-cirrhotic controls, in cirrhotic human livers there was a three-fold increase in CB1 receptors on isolated vascular endothelial cells. These results implicate anandamide and vascular CB1 receptors in the vasodilated state in advanced cirrhosis and indicate a novel approach for its management.

Animals↗
PubMed2001

Nonalcoholic steatohepatitis: association of insulin resistance and mitochondrial abnormalities.

BACKGROUND AND AIMS: The pathogenesis of nonalcoholic steatohepatitis (NASH) is unknown. We tested the hypothesis that NASH is associated with 2 defects: (1) peripheral insulin resistance, which increases lipolysis, delivery of free fatty acids (FFA) to the liver, and hepatic fatty acid beta oxidation, thereby creating oxidative stress; and (2) an abnormality within the hepatocytes that might render them more susceptible to injury from oxidative stress. METHODS: The hypothesis was tested by evaluation of (1) insulin resistance by a 2-step hyperinsulinemic (10 and 40 mU. m(-2). min(-1)) euglycemic clamp; (2) insulin effects on lipolysis by enrichment of [U-(13)C]glycerol; (3) frequency and severity of structural defects in hepatocyte mitochondria in vivo; (4) fatty acid beta oxidation from serum [beta-OH butyrate], release of water-soluble radioactivity from (3)H-palmitate by cultured fibroblasts and urinary dicarboxylic acid excretion; and (5) hepatic lipid peroxidation by immunohistochemical staining for 3-nitrotyrosine (3-NT). Subjects with NASH (n = 6-10 for different studies) were compared with those with fatty liver (n = 6) or normal controls (n = 6). RESULTS: NASH and fatty liver were both associated with insulin resistance, with mean glucose infusion rates (normal/fatty liver/NASH) of step 1, 4.5/1.6/0.9; step 2, 9.5/7.7/4.5 (P < 0.03 for both steps). Although baseline rates of glycerol appearance were higher in those with NASH than in those with fatty liver (means, 14.6 vs. 21.6 micromol. kg(-1). min(-1); P < 0.05), neither group significantly suppressed glycerol appearance at insulin infusion rates of 10 mU. m(-2). min(-1). NASH was associated with loss of mitochondrial cristae and paracrystalline inclusions in 9 of 10 subjects, compared with 0 of 6 subjects with fatty liver. However, no evidence of a generalized defect in fatty acid beta oxidation was noted in any group. Also, mean [beta-OH butyrate] was highest in those with NASH (means, 90 vs. 110 vs. 160 micromol/L; P < 0.04). Increased staining for 3-NT was present in fatty liver, and even greater staining was seen in NASH. CONCLUSIONS: These data indicate that peripheral insulin resistance, increased fatty acid beta oxidation, and hepatic oxidative stress are present in both fatty liver and NASH, but NASH alone is associated with mitochondrial structural defects.

Adult↗
PubMed2001

Development of nonalcoholic fatty liver disease after orthotopic liver transplantation for cryptogenic cirrhosis.

Many subjects with cryptogenic cirrhosis have underlying nonalcoholic steatohepatitis (NASH). The natural history of NASH-related cryptogenic cirrhosis after orthotopic liver transplantation (OLT) is not well defined. A primarily retrospective study of patients with the clinical histological phenotype of NASH-related cirrhosis undergoing OLT was performed. Data were compared with 2 sets of age- and weight-matched controls with (1) primary biliary cirrhosis or primary sclerosing cholangitis or (2) alcoholic liver disease. After OLT, all patients were managed by a standard immunosuppressive protocol. Liver biopsies were performed at 6 and 12 months after OLT and at 1- to 2-year intervals thereafter, as well as when liver enzyme levels were elevated enough to warrant diagnostic biopsy. Twenty-seven subjects with cryptogenic cirrhosis and a clinical histological phenotype of NASH and 3 patients with a long-standing diagnosis of NASH before OLT were included. The 30-day perioperative mortality was 1 in 30 patients. During a median follow-up of 3.5 +/- 2.7 years, 2 additional patients died of sepsis. There was a time-dependent increase in the risk for allograft steatosis that approached 100% by 5 years compared with only an approximately 25% incidence of steatosis in the control groups (P <.009, log-rank test). On multivariate analysis, only the cumulative steroid dose correlated with time to development of allograft steatosis. Three patients developed histological progression from hepatic steatosis to steatohepatitis. Of these, 1 patient developed progressive fibrosis. Four patients experienced at least 1 episode of acute cellular rejection; however, no patient developed chronic rejection or graft failure. In conclusion, nonalcoholic fatty liver disease occurs frequently after OLT in patients with the phenotype of NASH-related cirrhosis. Despite the frequent histological recurrence of disease, clinical outcomes are similar to those of other groups of patients undergoing OLT.

Adult↗
PubMed2001

Systemic and portal hemodynamic effects of anandamide.

The endogenous cannabinoid anandamide causes hypotension and mesenteric arteriolar dilation. A detailed analysis of its effects on systemic and portal venous hemodynamics had not yet been performed. We assessed the effects of anandamide (0.4-10 mg/kg) on systemic and portal hemodynamics with and without prior treatment with various antagonists. The specific antagonists used included SR-141716A, N(omega)-nitro-L-arginine methyl ester, indomethacin, and nordihydroguaiaretic acid. Anandamide produced a dose-dependent decrease in mean arterial pressure due to a drop in systemic vascular resistance (SVR) that was accompanied by a compensatory rise in cardiac output. Anandamide also elicited an increase in both portal venous flow and pressure, along with a decline in mesenteric vascular resistance (MVR). Pretreatment with 3 mg/kg SR-141716A, a CB(1) antagonist, prevented the decline of SVR and MVR from the lower dose of anandamide. Antagonism of nitric oxide synthetase, cyclooxygenase, or 5-lipoxygenase did not prevent the systemic nor the portal hemodynamic effects of anandamide. Furthermore, the use of R-methanandamide, a stable analog of anandamide, produced similar hemodynamic effects on the mesenteric vasculature, thereby implying that the effects of anandamide are not related to its breakdown products. Anandamide produced profound, dose-dependent alterations in both the systemic and portal circulations that could be at least partially blocked by pretreatment with SR-141716A.

Animals↗
PubMed2001

Minimizing ascites. Complication of cirrhosis signals clinical deterioration.

Ascites is the most common complication of cirrhosis. Its development is associated with a grave prognosis; 50% of patients die within 2 years of diagnosis. An understanding of the analysis of ascitic fluid is essential for the appropriate management of patients with liver disease and ascites. The management of patients with ascites involves a combination of dietary, medical, and surgical approaches. Furthermore, patients with ascites are at risk for ascitic fluid infections and neurohormonal dysregulation that can lead to hepatorenal syndrome. Early recognition of these complications allows therapeutic interventions that minimize further clinical deterioration in already chronically ill patients.

Ascites↗
PubMed2000

Chronic infection with hepatitis C virus in patients with elevated or persistently normal serum alanine aminotransferase levels: comparison of hepatic histology and response to interferon therapy.

Ninety-five patients with chronic hepatitis C virus (HCV) infection, 35 with persistently normal serum alanine aminotransferase (ALT) levels, were randomized to treatment with daily interferon (IFN) for 3 months, followed by IFN 3 times weekly (TIW) for 12 months (group A) or TIW for 18 months (group B). Patients with elevated versus normal ALT levels had similar demographic and virologic characteristics but significantly (P<.05) more advanced liver histology (bridging fibrosis and cirrhosis, 37.9% vs. 11.4%). After 3 months of treatment, 38.3% of patients in group A were HCV RNA negative versus 18.8% in group B (P<.05). When the IFN dose was reduced from daily to TIW in group A, the percentage of patients who remained HCV RNA negative declined; sustained virologic response was similar in both groups (10.6% vs. 8.3%). Response to treatment was similar in patients with elevated or normal ALT levels. Persons with chronic HCV infection and persistently normal serum ALT levels have milder liver disease than, and respond to IFN therapy similarly to, persons with elevated ALT levels.

Adult↗
PubMed2000

Selection and outcome of living donors for adult to adult right lobe transplantation.

BACKGROUND: The shortage of cadaveric livers has sparked an interest in adult-to-adult living donor transplantation. Right lobe donor hepatectomy is frequently required to obtain a graft of adequate size for adult recipients. Careful donor selection is necessary to minimize complications and assure a functional graft. METHODS: A four-step evaluation protocol was used for donor selection and satisfactory results of all tests in each step were required before proceeding to the next. Donors were selected based on a battery of laboratory studies chosen to exclude unrecognized infection, liver disease, metabolic disorders, and conditions representing undue surgical risk. Imaging studies included ultrasonography, angiography, magnetic resonance imaging, and intraoperative cholangiography and ultrasonography. The information obtained from liver biopsy was used to correct the estimated graft mass for the degree of steatosis. RESULTS: From March 1998 to August 1999, 126 candidates were evaluated for living donation. A total of 35 underwent donor right lobectomy with no significant complications. Forty percent of all donors that came to surgery were genetically unrelated to the recipient. A total of 69% of those evaluated were excluded. ABO incompatibility was the primary reason for exclusion after the first step (71%) and the presence of steatosis yielding an inadequate estimated graft mass after the second step (20%). CONCLUSIONS: Donor selection limits the application of living donor liver transplantation in the adult population. Unrelated individuals increase the size of the donor pool. Right lobe hepatectomy can be performed safely in healthy adult liver donors. Preoperative liver biopsy is an essential part of the evaluation protocol, particularly when the estimated graft mass is marginal.

Adult↗