An assessment of racial differences in the upper limits of normal ALT levels in children and the effect of obesity on elevated values.

OBJECTIVES: Childhood obesity is a risk factor for non-alcoholic fatty liver disease and poses important public health issues for children. Racial differences in alanine aminotransferase (ALT) levels among children have not been described. This study aimed to identify racial differences in upper limit normal (ULN) ALT levels and evaluate the effect of obesity on elevated levels in children without other metabolic risk factors. METHODS: National Health and Nutrition Examination Surveys and clinical data from the Loyola University Health System were used to determine ULN ALT by race and gender. Quantile regression was used to evaluate the impact of obesity on elevated ALT and to identify potential risk factors for ALT above the ULN. RESULTS: Upper limit normal (ULN) ALT was approximately 28.0 and 21.0-24.0 U/L for boys and girls, respectively. No significant difference in ULN ALT across race was observed. Obesity was significantly associated with elevated ALT; obese children with elevated ALT had values 10 U/L higher than normal-weight children. CONCLUSIONS: Racial differences in ALT levels among adults are not evident in children. Obesity, in the absence of metabolic risk factors and other causes of liver disease, is associated with elevated ALT, providing evidence against the concept of healthy obesity in children.

Characterizing hepatitis B stigma in Chinese immigrants.

Health-related stigma is a cause of stress, alienation and discrimination that can serve as a barrier to prevention and care for infectious diseases such as HIV. Hepatitis B virus (HBV)-related stigma is common in Asian immigrants, but has not been formally evaluated. The aim of this study was to develop and validate the first HBV stigma instrument and to begin to evaluate HBV stigma in Chinese immigrants. The HBV stigma instrument was developed based on constructs from validated HIV stigma scales and organized into five domains. A written survey was compiled to include demographic data, HBV knowledge questions and stigma items. The survey was pilot tested in English and Chinese and then finalized. Data were obtained from 201 patients seen in an urban Chinatown Internal Medicine practice. The stigma items showed a high degree of reliability when assessed in aggregate (α = 0.85) as well as within individual domains. Stigma was greatest in the Fear of Contagion domain. Knowledge questions showed a corresponding deficit in understanding of modes of HBV transmission. An inverse relationship between stigma scores and familiarity with HBV provided evidence of construct validity. In multivariable analysis, having a family member with HBV and higher HBV knowledge subset scores were associated with lower degrees of stigma. In conclusion, the hepatitis B stigma instrument showed reliability and construct validity. The relationship identified between familiarity and knowledge regarding HBV with lower stigma scores provides the basis for the development of interventions to reduce HBV stigma.

Very early prediction of response to HCV treatment with PEG-IFN-alfa-2a and ribavirin in HIV/HCV-coinfected patients.

The objective of this study was to find very early viral kinetic markers to predict nonresponse to hepatitis C virus (HCV) therapy in a group of human immunodeficiency virus (HIV)/HCV-coinfected patients. Twenty-six patients (15 HCV genotype-1 and 11 genotype-3) were treated with a 48-week regimen of peginterferon-alfa-2a (PEG-IFN) (180 µg/week) and weight-based ribavirin (11 mg/kg/day). Samples were collected at baseline; 4, 8, 12, 18, 24, 30, 36 and 42 h; days 2, 3, 4, 7, 8, 15, 22, 29, 43 and 57 then weekly and monthly. Five patients discontinued treatment. Seven patients (27%) achieved a sustained virological response (SVR). Nadir HCV RNA levels were observed 1.6 ± 0.3 days after initiation of therapy, followed by a 0.3- to 12.9-fold viral rebound until the administration of the second dose of PEG-IFN, which were not associated with SVR or HCV genotype. A viral decline <1.19 log for genotype-1 and <0.97 log for genotype-3, 2 days after starting therapy, had a negative predictive value (NPV) of 100% for SVR. The day 2 virological response had a similar positive predictive value for SVR as a rapid virological response at week 4. In addition, a second-phase viral decline slope (i.e., measured from day 2 to 29) <0.3 log/week had a NPV = 100% for SVR. We conclude that first-phase viral decline at day 2 and second-phase viral decline slope (<0.3 log/week) are excellent predictors of nonresponse. Further studies are needed to validate these viral kinetic parameters as early on-treatment prognosticators of nonresponse in patients with HCV and HIV.

The prevalence and clinical correlates of elevated ALT levels in an urban Chinatown community.

Alanine aminotransferase (ALT) levels are a primary consideration in treatment decisions regarding hepatitis B virus (HBV) infection. Levels can be elevated as a result of HBV-related liver injury or to other causes. The aim of this study was to assess the background prevalence and clinical correlates of elevated ALT levels in Chinese immigrants who were HBsAg negative. Subjects consisted of adults seen in an urban Chinatown Internal Medicine practice between 1, 2006 and 12, 2007. Clinical information was collected retrospectively. An elevated ALT level was defined as >19 U/L for women and >30 U/L for men. The primary analysis focused on 2457 persons who were HBsAg negative. Their mean age was 55 +/- 18 years, 64% were female and 36% were obese. All subjects were ethnically Chinese and 96% were born in Asia. Thirty percent had an elevated ALT level. In univariate analysis, factors associated with elevated ALT included older age (P < 0.001), female gender (P = 0.001), obesity (P < 0.001), diabetes (P < 0.001), hypercholesterolemia (P < 0.001) and hypertension (P < 0.001). In multivariate analysis BMI, diabetes, female gender and hypercholesterolemia were significantly associated with elevated ALT level. An additional analysis focused on a group of patients who were HBsAg positive, HBeAg negative and had HBV-DNA levels <1000 copies/mL. Fifty percent had elevated ALT levels. In conclusion, elevated ALT levels are common among Chinese immigrants without HBV (30%) and are associated with features of the metabolic syndrome. Liver biopsy should be performed in selected patients with HBV to distinguish the cause of ALT elevation before initiating antiviral therapy.

A novel anticancer agent ARC antagonizes HIV-1 and HCV.

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) pose major public health concerns worldwide. HCV is clearly associated with the occurrence of hepatocellular carcinoma, and recently HIV infection has also been linked to the development of a multitude of cancers. Previously, we identified a novel nucleoside analog transcriptional inhibitor ARC (4-amino-6-hydrazino-7-beta-D-ribofuranosyl-7H-pyrrolo[2,3-d]-pyrimidine-5-carboxamide) that exhibited proapoptotic and antiangiogenic properties in vitro. Here, we evaluated the effect of ARC on HIV-1 transcription and HCV replication. Using reporter assays, we found that ARC inhibited HIV-1 Tat-based transactivation in different cell systems. Also, using hepatoma cells that harbor subgenomic and full-length replicons of HCV, we found that ARC inhibited HCV replication. Together, our data indicate that ARC could be a promising candidate for the development of antiviral therapeutics against HIV and HCV.

Ethnic differences in the presentation of chronic hepatitis C.

Hispanics comprise 13% of the population in the United States and are the fastest growing minority group. Features of hepatitis C in Hispanics have not been well characterized. The aims of this study were to compare features of hepatitis C among Hispanics, Whites, and African-Americans and to characterize hepatitis C infection in Hispanics. A retrospective analysis was performed on 1225 consecutive patients with hepatitis C seen at the University of Illinois at Chicago including 227 Hispanics, 508 Whites, and 490 African-Americans. Data collection consisted of demographic variables, risk factors for hepatitis C, history of alcohol use, laboratory parameters and liver histology. Pair-wise comparisons showed that Hispanics had higher aminotransferase levels than Whites and African-Americans. Hispanics had higher portal inflammation scores on liver biopsy than African-Americans (P = 0.002) and Whites (P = 0.043). Hispanics had a higher frequency of cirrhosis than African-Americans (P < 0.001) and a trend towards more cirrhosis than Whites (P = 0.165). There was a trend towards a higher prevalence of cirrhosis in Hispanic women (56%) than in Hispanic men (45%) [P = 0.14]. A cross-sectional analysis of patients at our liver center showed that Hispanics with hepatitis C had higher aminotransferase levels, more portal inflammation than Whites and African-Americans, and a higher prevalence of cirrhosis than African-Americans.

Risk factors for failure to meet listing requirements in liver transplant candidates with alcoholic cirrhosis.

BACKGROUND: The majority of liver transplant centers require a 6-month abstinence period before listing candidates for liver transplantation with alcoholic cirrhosis and a persistent sobriety thereafter. We attempted to identify risk factors for failure to comply with these requirements. METHODS: Ninety-nine consecutive patients with alcoholic cirrhosis were referred for liver transplant evaluation between September 1996 and May 1998. The mean age was 49 years, 74% were male, and 54% were hepatitis C virus positive. To be listed, patients had to meet the following requirements. All patients received extensive psychosocial evaluations and were frequently monitored with random urine and blood alcohol tests; patients found positive were excluded or removed from the liver transplant waiting list. Detailed patient information was entered into a computerized database, and 36 discreet variables were analyzed in relation to success (patient listed and remained on the list) or failure (not listed or removed from the list based on noncompliance). RESULTS: Forty-nine patients were successfully listed. Nineteen received a transplant, with a 95% 1-year patient and graft survival rate and 21% alcohol relapse rate after transplantation. Twenty-two patients had either medical contraindication and/or died before transplant listing. Twenty-four patients were never listed and four were removed from the list due to recurrent alcoholism, for a total of 28 failures. Our statistical analysis identified five significant risk factors for failure: (I) living arrangement (alone/family versus community/friend), P=0.006; (II) history of suicide ideation, P=0.03; (III) history of previous alcohol-related hospitalization, P=0.01; (IV) lack of previous alcoholic rehabilitation before transplant evaluation, P=0.001; and (V) failure to accept further alcoholic rehabilitation before orthotopic liver transplantation, P=0.01. CONCLUSIONS: Our experience confirms that transplantation can be extremely successful in properly selected patients with alcoholic cirrhosis. We identified several predictive psychosocial factors of early alcoholic recidivism in transplant candidates.

The human Na(+)/H(+) exchanger NHE2 gene: genomic organization and promoter characterization.

The Na(+)/H(+) exchanger (NHE) 2 belongs to a family of plasma membrane transporters involved in intracellular pH and cell volume regulation. We recently reported cloning of human NHE2 (hNHE2) from a colonic cDNA library. Northern blot analysis has identified NHE2 mRNA only in small intestine, prostate, kidney, colon, and skeletal muscle. In this study, we describe the structure and 5'-regulatory region of the hNHE2 gene. The hNHE2 gene spans >90 kb and is organized in 12 exons intervened by 11 introns. All introns contain the conserved GT and AG dinucleotides at the donor and acceptor sites, respectively. The hNHE2 gene was mapped to chromosome 2q11.2. Primer extension analysis revealed a single transcription initiation site in human colonic adenocarcinoma cell lines. Analysis of the DNA nucleotide sequences of a 1.4-kb fragment of the 5'-flanking region shows no canonical TATA or CAAT boxes. However, the promoter region contains several potential cis-regulatory elements such as Sp1, early growth response-1, activator protein-2, MyoD, p300, nuclear factor-kappaB, myeloid zinc finger protein-1, caudal-related homeobox (Cdx) gene A, and Cdx protein-2 binding sites. In transient transfection studies, a reporter construct containing the 1.4-kb promoter region exhibited low luciferase activity levels. However, after deletion upstream of -664, its activity increased approximately threefold. Thus our data suggest that an inhibitory element may exist in the NHE2 promoter 5'-upstream region.

Human intestinal anion exchanger isoforms: expression, distribution, and membrane localization.

A family of anion exchangers (AEs) including AE1, AE2 and AE3 has been described. AE3 gene has been shown to encode two alternatively spliced isoforms termed as bAE3 (brain subtype) and cAE3 (cardiac subtype). The identity of the AE(s) involved in the human intestinal NaCl absorption is not fully understood. Current studies were undertaken to identify the AE isoforms expressed in the human intestine, to define their regional and vertical axis (crypt vs. surface cells) distribution, and to elucidate their membrane localization in the epithelial cells along the entire length of the human intestine. Our studies utilizing reverse transcription (RT)-PCR with total RNA extracted from pinch biopsies from various regions of the human intestine demonstrate that AE2 and bAE3 but not AE1 or cAE3 were expressed in all the regions of the human intestine. Utilizing in situ RT-PCR, we demonstrated that the message of AE2 was expressed throughout the vertical surface--crypt axis of the colon. Our Western blotting studies demonstrated that AE2 and bAE3 are localized to the basolateral but not the apical membranes of the intestinal epithelial cells from the human ileum and colon. In conclusion, our results demonstrated that in the human intestine, AE2 and bAE3, but not AE1 or cAE3, are expressed throughout the tract with the highest expression in the colon compared to the ileum and jejunum. Both the isoforms were found to be localized to the basolateral but not the apical membranes of the epithelial cells. We speculate that, in the human intestine, AE2 and bAE3 may be the 'housekeeping' isoforms, and the apical AE, the potential candidate for chloride absorption, remains to be identified.

Mechanism(s) of butyrate transport in Caco-2 cells: role of monocarboxylate transporter 1.

The short-chain fatty acid butyrate was readily taken up by Caco-2 cells. Transport exhibited saturation kinetics, was enhanced by low extracellular pH, and was Na(+) independent. Butyrate uptake was unaffected by DIDS; however, alpha-cyano-4-hydroxycinnamate and the butyrate analogs propionate and L-lactate significantly inhibited uptake. These results suggest that butyrate transport by Caco-2 cells is mediated by a transporter belonging to the monocarboxylate transporter family. We identified five isoforms of this transporter, MCT1, MCT3, MCT4, MCT5, and MCT6, in Caco-2 cells by PCR, and MCT1 was found to be the most abundant isoform by RNase protection assay. Transient transfection of MCT1, in the antisense orientation, resulted in significant inhibition of butyrate uptake. The cells fully recovered from this inhibition by 5 days after transfection. In conclusion, our data showed that the MCT1 transporter may play a major role in the transport of butyrate into Caco-2 cells.

Hepatitis C kinetics: mathematical modeling of viral response to therapy.

Mathematical models have been used to study the dynamics of HIV. Using these same principles, the dynamics of hepatitis C virus (HCV) are reviewed during interferon (IFN) therapy. After initiating IFN treatment, there is an IFN dose-dependent exponential decline in viral RNA levels within the first 48 hours. This rapid 1.0 to 2.0 log decline was best explained by an effect of IFN in inhibiting viral production with a varying degree of effectiveness. By applying mathematical principles, viral serum half-life was estimated to be 3.0 hours and viral production rat was calculated to be 1.0 x 10(12) virions per day. After this rapid first-phase decline there was a slower second phase decline in viral levels that was highly variable between subjects. This phase was dependent on the rate of elimination of HCV-infected liver cells. The rapidity of the second phase proved to be the best predictor of early viral clearance. The use of these models to understand the life cycle of viruses and their response to therapy is reviewed.

Differences in viral dynamics between genotypes 1 and 2 of hepatitis C virus.

Many studies have shown that patients infected with hepatitis C virus (HCV) of genotype 2 have better response to interferon (IFN)-alpha treatment than genotype 1 patients; however, the mechanisms responsible for this difference are not understood. In this study, viral dynamics during high-dose IFN induction treatment were compared between the genotypes. Patients in each group received 10 MU of IFN-alpha2b for 14 days, and HCV RNA levels were frequently determined. Nonlinear fitting, both individually for each patient and using a mixed-effects approach, of the viral kinetic data to a mathematical model of the IFN effect on HCV infection was performed. The antiviral effectiveness of IFN in blocking virus production, the free virion clearance rate, and the HCV-infected cell death rate were all significantly higher for genotype 2 patients than for genotype 1 patients. Thus, the better response rate of patients infected with HCV genotype 2 is multifactorial. This is the first finding of a difference in viral dynamics between subtypes of the same virus and demonstrates the importance of subtype-specific virus-host-drug interactions.

Molecular cloning, tissue distribution, and functional expression of the human Na(+)/H(+) exchanger NHE2.

In the present report, we describe the cloning of a human colonic cDNA that describes the full-length Na(+)/H(+) exchanger (NHE) 2 coding region. The human NHE2 (hNHE2) cDNA encodes for a polypeptide of 812 amino acids with a 90% overall identity to both rabbit and rat NHE2 isoforms. In comparison with SLC9A2, recently reported as the human NHE2, the hNHE2 polypeptide is 115 amino acids longer in the NH(2)-terminal end and shows only an 84% DNA nucleotide sequence identity. Northern blot analysis revealed that hNHE2 message has an uneven tissue distribution, with high levels in the skeletal muscle, colon, and kidney and lower levels in the testis, prostate, ovary, and small intestine. Protein expression studies with hNHE2 clone showed that a 75-kDa protein was expressed. Stable expression of transfected full-length hNHE2 cDNA in Na(+)/H(+) exchange-deficient LAP1 cells exhibited Na(+)-dependent pH recovery after an acid prepulse that was inhibited by 0.1 mM amiloride. These data indicate that this cDNA is the true human NHE2 cDNA and that the encoded protein is capable of catalyzing Na(+)/H(+) exchange activity.

Is the presence of surgically treatable coronary artery disease a contraindication to liver transplantation?

Advanced coronary artery disease has been traditionally considered an absolute contraindication to orthotopic liver transplantation where chronic liver failure significantly increases the surgical risk for coronary artery bypass grafting. Performing a simultaneous coronary artery bypass grafting and liver transplant is a theoretically attractive strategy in liver transplant candidates with coronary artery disease in need of revascularization. In the present article, we report a successful simultaneous coronary artery bypass grafting and orthotopic liver transplant with 1-yr post-operative follow-up and we discuss the rationale for this approach. In selected cases, the presence of advanced coronary artery disease should not be considered an absolute contraindication to liver transplantation.

Hepatitis C viral dynamics.

It is apparent that the sooner the virus is cleared from the serum following IFN monotherapy, the better the sustained virologic response rates. It is also clear that in patients infected with HCV genotype 1a and 1b, standard dosages of IFN-alpha 2b (3 MU) administered three times a week are inadequate for a substantial and sustained lowering of HCV RNA serum levels. Understanding the kinetics and dynamics of HIV and HBV has greatly improved the understanding of the life cycle of these viruses and their response to therapy. Studies of the kinetics of HCV following initiation of IFN monotherapy have revealed that IFN-alpha 2b causes a rapid dose-dependent (3 < 5 < 10 = 15 MU) reduction in HCV RNA levels within 24 to 48 hours. This rapid exponential decline in RNA levels is best explained by an effect of IFN on viral production or release. The dose of other IFN products that maximally suppresses viral levels needs to be determined. Mathematical calculations reveal that HCV has a serum half-life of 3 hours and a viral production rate of 1.0 x 10(12) virions/d. After this rapid decline, there is a slower phase of viral decline that varies widely among patients and is attributed to the death rate of infected liver cells. The rate of decline of the second phase, which is probably mediated by immune clearance of infected liver cells, is the best viral kinetic predictor of early viral clearance. This kinetic information indicates that in patients infected with HCV genotype 1a or 1b, initial therapy with IFN should be daily and initial doses should be sufficient to reduce viral levels by more than 95% within 48 hours. Whether higher doses of IFN will alter or enhance the second phase of viral decline needs to be investigated. Also, the effect of ribavirin on IFN-mediated changes in HCV RNA levels needs to be investigated in carefully performed kinetics studies to better determine its mechanism of action. Defining the viral kinetics in patients infected with HCV genotype 2 or 3 and in patients who do not respond to IFN therapy will also improve the approach to therapy.

Principles of interferon induction therapy.

Several strategies have been devised to enhance the number of patients with hepatitis C virus (HCV) infection who achieve a sustained response to interferon-alpha therapy. Induction therapy uses higher than usual doses of interferon, given on a daily, rather than three times per week basis, for a defined period. The goal is to minimize fluctuations in interferon levels, preventing viral rebound in periods when drug levels are low. The optimal interferon-alpha-2b dose for acute viral clearance is probably 10 MIU. Studies of HCV viral kinetics after interferon-alpha dosing have shown a biphasic response to drug. In the initial 24 to 48 hours after a dose of interferon, there is an extremely rapid, interferon-dose-dependent decrease in viral titer. This reflects inhibition of viral production and/or release. The second lower phase of viral decrease then ensues, which is highly variable between patients. It is thought to reflect the death rate of infected hepatocytes. Brisk decrease during the second phase of viral kinetics is the best predictor of HCV-RNA clearance by 3 months. Second-phase viral decrease correlates with histologic activity on liver biopsy and pretreatment serum transaminase levels. Hepatitis C virus genotype differences are important, as well, because genotypes 2 and 3 are cleared by interferon more readily than the more resistant genotype 1.