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M de Medina

Publications and source records attributed to M de Medina.

At least 19 recordsLinked to original sources
PubMed2000

Randomized, cross-over, controlled comparison of two inactivated hepatitis A vaccines.

The immunogenicity, tolerability and interchangeability of two hepatitis A vaccines, Vaqta (Merck and Co.) and Havrix (SmithKline) were studied in a randomized, crossover, controlled clinical trial. Vaccine was administered to 201 volunteers at 0 and 26 weeks in one of four vaccine regimens: Havrix-Havrix; Havrix-Vaqta; Vaqta-Havrix or Vaqta-Vaqta. Seroconversion rates (>/=10 mIU/ml) for those whose first dose was Vaqta or Havrix, respectively, were: 41/96 (43%) versus 30/95 (32%) (P=0.15) at 2 weeks and 91/98 (93%) versus 84/97 (87%) (P=0.43) at 4 weeks, and 100% at 26 weeks. Geometric mean concentrations (GMC) of total antibody to hepatitis A virus (anti-HAV) for Vaqta and Havrix were 189 and 114 mIU/ml (P=0.011) at 4 weeks and 234 and 136 mIU/ml (P<0.001) at 26 weeks. At 30 weeks, the GMC after two doses of Havrix was 2612 mIU/ml compared with 5497 after two doses of Vaqta (P<0.001). The GMC in the Havrix-Vaqta group was 5672 mIU/ml compared with 3077 mIU/ml in the Vaqta-Havrix group (P<0.001). Less than half of vaccine recipients reported tenderness or pain. In this study, seroconversion rates of the two vaccines were similar. Vaqta produces significantly higher anti-HAV antibody than Havrix. Crossover immunization is well tolerated and results in high antibody concentrations, especially when Vaqta is the booster dose. The significance of higher anti-HAV antibody concentrations in terms of long-term protection is unknown.

Adult↗
PubMed2000

Measurement of serum hyaluronic acid in patients with chronic hepatitis C and its relationship to liver histology. Consensus Interferon Study Group.

BACKGROUND AND AIMS: Chronic hepatitis C is a slowly progressing inflammatory disease of the liver that can lead to cirrhosis and its complications. Assessment of liver damage in hepatitis C has been primarily via histological evaluation. Liver biopsy, while useful in determining the extent of liver damage, has associated costs and places patients at a small but finite risk of bleeding. Studies in small patient populations have identified serum markers shown to correlate with liver histology, including procollogen III peptide and hyaluronic acid (HA). To determine whether serum HA was a reliable predictor of cirrhosis and fibrosis, we examined serum HA concentrations from 486 chronic Hepatitis C virus (HCV) patients. METHODS AND RESULTS: Patients were anti-HCV and HCV RNA positive, with elevated alanine aminotransferase values and underwent a liver biopsy. Sera were obtained at the baseline for HA using radioimmunoassay methodology. Patients with cirrhosis had significantly higher serum HA concentrations compared with non-cirrhotic patients (382+/-31 vs 110+/-9 microg/L respectively, P< 0.001). Patients with fibrosis had significantly higher mean serum HA concentrations (179+/-11 microg/L) compared with patients without fibrosis (62+/-20 microg/L; P< 0.001). The correlation between HA concentration and the components of the Knodell histological activity index score revealed no strong associations with the exception of fibrosis, which showed moderate correlation (R=0.5421, P<0.001). The clinical value of HA measurement appears to be its ability to exclude cirrhosis. A HA value of < 60 microg/L excluded the presence of cirrhosis or significant fibrosis with a predictive value of 99 and 93%, respectively. CONCLUSIONS: Serum HA measurement may be clinically useful to non-invasively assess the degree of fibrosis and cirrhosis. Further prospective studies are warranted to determine the clinical utility of HA as a non-invasive marker of liver fibrosis.

Adult↗
PubMed2000

A multicenter study evaluation of the digene hybrid capture II signal amplification technique for detection of hepatitis B virus DNA in serum samples and testing of EUROHEP standards.

We have evaluated the new Digene Hybrid Capture II HBV DNA Test (HCII HBV), which is a 96-well microtiter plate-based signal amplification assay. This test uses hybrid capture technology that specifically detects RNA-DNA hybrids. HCII HBV is able to quantify hepatitis B virus (HBV) DNA at between 1.4 x 10(5) and 1.7 x 10(9) HBV copies per ml in a standard format. By using a modified sample preparation method, which allows the input of 30-fold more serum for an ultrasensitive format, the sensitivity of the assay can be increased reproducibly to approximately 8,000 copies of HBV per ml. By using a combination of these two formats, the assay can quantify over a total range of 6 logs. In our multicenter evaluation study, the mean laboratory-to-laboratory coefficients of variation were 22, 7, and 12% at the three sites, respectively, with a combined specificity of 98.4%. The linearities of both the standard test and the ultrasensitive test were excellent, with Spearman correlation coefficients of 0.997 and 0.999, respectively. Furthermore, the intra-assay reproducibility for the standard assay gave coefficients of variation of from 13 to 33, 9 to 21, and 3 to 8% at the three sites, respectively. HCII HBV was shown to be genotype independent when the EUROHEP standards for genotypes A and D were used. This assay allows the accurate measurement of HBV DNA levels in serum and can be clinically used for the monitoring of responses to antiviral agents for patients chronically infected with HBV.

DNA, Viral↗
PubMed1999

New perspectives in the diagnosis of hepatitis C.

Since the identification and molecular characterization of the non-A, non-B hepatitis virus (HCV) in 1989, a variety of diagnostic tests based on the detection of hepatitis virus antibodies or HCV RNA in the serum have been developed and refined. The enzyme-linked immunosorbent assays (ELISAs) and the recombinant immunoblot assays (RIBAs) exhibit improved sensitivity and specificity for HCV antibodies compared with their predecessors, and the ELISA-3 is at the forefront of HCV screening. Furthermore, the advent of molecular assays that employ quantitative reverse-transcriptase polymerase chain reaction to detect HCV RNA has allowed clinicians to track the natural history of HCV and to monitor the progress of therapy. A role for further refinement of an HCV diagnosis using tests to determine genotype, subtype, and quasispecies is explored. In addition, the role of liver biopsy and non-invasive markers of histologic status are placed into the context of patient prognosis. This article reviews the state-of-the-art tests and assays developed for the diagnosis and management of HCV infection.

Enzyme-Linked Immunosorbent Assay↗
PubMed1998

Diagnostic tools in the evaluation of patients with viral hepatitis undergoing liver transplantation.

Familiarity with the diagnostic parameters of viral hepatitis is imperative in the liver transplantation arena. Chronic viral hepatitis B and C are among the most common categories of end-stage liver disease. The preoperative diagnosis, determination of recurrent infection, and the assessment of antiviral therapeutic efficacy are dependent on appropriate virological testing. Furthermore, liver transplant personnel are at a high risk for parenterally transmitted viral hepatitis infection. Knowledge and understanding of the serological patterns of acute and chronic viral hepatitis, as well as recognition of the immune status for one or more of these viruses, will facilitate prevention and treatment of viral hepatitis for these health care providers.

Acute Disease↗
PubMed1998

Detection of anti-hepatitis C virus antibodies in patients undergoing dialysis by utilizing a hepatitis C virus 3.0 assay: correlation with hepatitis C virus RNA.

Hepatitis C virus (HCV) infection is endemic in long-term dialysis units. We assessed the performance of a recently developed HCV 3.0 assay for the detection of HCV antibodies in patients undergoing dialysis. The study evaluated 128 patients undergoing long-term maintenance hemodialysis. Anti-HCV was detected by 2.0 and 3.0 enzyme immunoassay (EIA). Results were confirmed with recombinant immunoblot assays (RIBA 2.0 and RIBA 3.0). HCV RNA was detected by using reverse transcriptase-polymerase chain reaction (RT-PCR). Thirty-two patients (25%) were HCV EIA 2.0 positive. Of these, 1 was RIBA 2.0 negative (PCR positive), 3 were indeterminate (3 PCR positive), and 28 were positive (23 PCR positive). Thirty-five (27%) were HCV EIA 3.0 positive. One was RIBA 3.0 negative (PCR positive), 1 was indeterminate (c33c, PCR positive), and 33 were positive (27 PCR positive) by RIBA 3.0. Thus only 1 PCR-positive patient was negative with RIBA 2.0 and 3.0 assays. Two of the 3 RIBA 2.0 indeterminate samples were positive with RIBA 3.0. One remained indeterminate but was HCV RNA positive. In summary, HCV 3.0 EIA detected 4 additional viremic patients but was positive in 6 PCR-negative subjects. A high correlation of the presence of antibody to c33c with HCV RNA (28 of 34, 82%) was found, and it was found in all anti-HCV positive samples and in 1 indeterminate sample. We conclude that the HCV EIA 3.0 test with the supplemental confirmatory RIBA 3.0 test may improve the sensitivity for the detection of anti-HCV. Nevertheless, in potentially immunocompromised patients undergoing dialysis, PCR continues to be the only reliable test for detecting viremia.

Adult↗
PubMed1998

Prevalence of hepatitis C and G virus infection in chronic hemodialysis patients.

An RNA virus designated hepatitis G virus (HGV) has been recently identified in patients with acute and chronic liver disease. HGV is transfusion transmissible, it has global distribution, and it is present in the volunteer blood donor population in the United States. One hundred sixty patients undergoing maintenance hemodialysis at the University of Miami-affiliated unit were evaluated. There were 99 men and 61 women ranging in age from 22 to 80 years. Sixty percent had a history of blood transfusion, 6% had a history of drug abuse, and 9% were infected with the human immunodeficiency virus. HGV-RNA was detected by reverse-transcriptase polymerase chain reaction with amplification of two independent regions (5'-nontranslated region and NS5a coding region). Detection of digoxigenin-labeled amplification products with specific capture probes to the coding and noncoding regions was performed with the Enzymun-test DNA on an ES-300 Immunoassay System (Boehringer-Mannheim, Mannheim, Germany). Hepatitis C antibodies were measured with anti-hepatitis C virus enzyme-linked immunosorbent third-generation assays and hepatitis C virus RNA by reverse-transcriptase polymerase chain reaction. There were 32 (20%) patients with detectable HGV RNA with both primer pairs. Because of possible mutations, the HGV virus may be detectable only with one primer pair. We considered the latter as indeterminate: 12 had detectable levels to the NS5a region only, seven to the 5'-nontranslated region, and six had borderline results. Detectable and indeterminate samples were confirmed by repeat measurements in a new blood sample. Seven of 24 (29%) patients with detectable hepatitis C virus RNA had coexisting HGV with one or both HGV primer pairs (four with both and three with one). Five patients were hepatitis B surface antigen positive and HGV negative. We conclude that HGV infection is prevalent in our dialysis patients. The clinical significance of HGV infection remains to be established.

Adult↗
PubMed1995

Absence of anti-LKM-1 antibody in hepatitis C viral infection in the United States of America.

Several studies from Europe have observed a relationship between hepatitis C virus infection and anti-liver/kidney microsome-1 (anti-LKM-1) positive chronic hepatitis. It has been suggested that hepatitis C may induce an autoimmune phenomenon that leads to the development of a specific type (type II anti-LKM-1 positive) autoimmune chronic hepatitis. We evaluated 204 sera from patients with well-documented hepatitis C infection from two centres in the United States of America and compared them with sera from 428 French patients from three centres. We evaluated the serological prevalence of anti-smooth muscle antibodies, anti-nuclear antibodies, anti-liver cytosol antibodies, and anti-mitochondrial antibodies subtype anti-M2 in patients with chronic hepatitis C. The two groups were matched in their ages, gender, mode of transmission of hepatitis C infection and severity of liver disease. Anti-LKM-1 was not observed in the patients from the USA at a time when it was noted in 3.7% of French patients. There were no differences, however, in the expression of other auto-antibodies, which were often in low titres. Absence of anti-LKM-1 in USA sera in comparison with French sera suggests that there may be differences in induction of anti-LKM-1 related to environmental and/or host genetic factors, and/or genomic variation in the hepatitis C virus.

Age Factors↗
PubMed1995

Identification of hepatitis C virus by immunoelectron microscopy.

Sequencing of the hepatitis C virus (HCV) has provided a better understanding of the natural history, immunology, and epidemiology of this virus. However, the morphology of HCV has not been definitively characterized. In this study, through a sequence of concentration processes, virus-like particles were isolated from human serum and liver tissue, visualized by transmission electron microscopy and identified as hepatitis C virion by immunoelectron microscopy. Spherical flavi-like virus particles, approximately 70 nm in diameter, were observed in the fraction with 1.04-1.12 g ml-1 sucrose density and bound to immunogold particles with monoclonal antibodies (mAb) against hepatitis C. The nucleocapsid of the particles, which were 50 nm in diameter, appeared to be icosahedral in structure and surrounded by an envelope covered with surface projections. A 'tadpole' form of particles was also observed. The findings indicate that the low buoyant density in sucrose and the morphological features of the hepatitis C virion are consistent with the characteristics of flaviviruses and pestiviruses.

Animals↗
PubMed1995

Hepatitis C virus in alcoholic patients with and without clinically apparent liver disease.

A high prevalence of antibodies to the hepatitis C virus (anti-HCV) has been demonstrated among patients with alcoholic liver disease, whereas the prevalence of HCV viremia in these patients remains uncertain. The aims of this study were to determine the prevalence of anti-HCV in alcoholic patients both with and without clinically apparent liver disease and to determine the presence of HCV RNA in those patients who tested positive for anti-HCV by RIBA II (Chiron Corporation, Emeryville, CA). One hundred male patients consecutively admitted to an alcoholic rehabilitation program were included. Group 1 was comprised of 40 patients with clinically apparent liver disease. Group 2 was comprised of 60 patients without clinically apparent liver disease. Anti-HCV was performed by a second-generation ELISA assay and confirmed by RIBA II. HCV RNA was performed by Quantiplex assay (Chiron Corporation) and a nested reverse transcriptase-polymerase chain reaction. No significant differences were found between the two groups with regards to age, quantity and duration of alcohol intake, or accepted risk factors for HCV. The overall prevalence of anti-HCV in our patients was 23%, with 43% of these in group 1 and 10% in group 2. HCV RNA tested positive in 94% of the anti-HCV-positive patients in group 1 and in 67% of the anti-HCV-positive patients in group 2. These data suggest that HCV infection is an important cofactor in the pathogenesis of liver disease among alcoholic patients.

Adult↗
PubMed1995

Procollagen-III peptide and chronic viral C hepatitis.

UNLABELLED: Chronic hepatitis develops in at least half of persons acutely infected with hepatitis C virus (HCV). Ten to 25% of these patients will develop cirrhosis. Serum procollagen-III peptide (PIIIP) may be of value in predicting the development of chronic active fibrogenic liver disease. It has been reported that in chronic viral C hepatitis, the levels of hepatitis C virus-RNA (HCV-RNA) correlate directly with the severity of hepatic histology and inversely with response to interferon therapy. OBJECTIVES: The aims of this study were to correlate the level of PIIIP with HCV-RNA concentrations, ALT values, and histological severity in patients with chronic viral C hepatitis. METHODS: Eighty-six patients with chronic C hepatitis were divided into three groups: group I (n = 34), mild chronic active hepatitis, group II (n = 25), moderate to severe chronic active hepatitis, and group III (n = 27), cirrhosis. HCV-RNA was measured by Quantiplex, and PIIIP was measured by radioimmunoassay-gnostic assay. RESULTS: Mean +/- SD level of ALT in group I was 114 +/- 48 U/L, group II was 169 +/- 115 U/L, and group III was 160 +/- 94 U/L. The mean +/- SD level of HCV-RNA in group I was 110 +/- 130 x 10(5) Eq/ml, in group II was 140 +/- 140 x 10(5) Eq/ml, and in group III was 70 +/- 80 x 105 Eq/ml. The mean +/- SD level of PIIIP in group I was 0.6 +/- 0.2 U/ml, in group II was 0.9 +/- 0.4 U/ml, and in group III was 1.2 +/- 0.6. There was a significant difference in the levels of PIIIP among the three groups (p = 0.0001). There was no correlation among ALT, HCV-RNA, and PIIIP in any of the three groups. CONCLUSIONS: PIIIP peptide determinations in patients with chronic viral C hepatitis are reflective of histological severity and may provide relatively noninvasive means of following disease progression.

Alanine Transaminase↗
PubMed1994

Detection of hepatitis C virus RNA in hemodialysis patients.

The clinical significance of the high prevalence of antibodies to hepatitis C virus (HCV) in dialysis patients remains undefined. In order to assess the relationship between seropositivity and potential infectivity, 63 patients undergoing maintenance hemodialysis were evaluated between April and May 1990. The mean duration of maintenance hemodialysis was 45 mo (range, 13 to 144). Eighty-two percent (52 of 63) had received blood transfusions, and 16% (10 of 63) had a history of iv drug abuse. Serum samples were analyzed by HCV-cDNA polymerase chain reaction; antibodies to HCV structural (core) and nonstructural regions NS3 and NS4 were determined by enzyme immunoassay. Specimens repeatedly reactive for anti-HCV and HCV-RNA-positive samples were tested by HCV MATRIX dot immunoblot assay and HBV-DNA PCR. Twenty-five percent (16 of 63) were anti-HCV-positive. Of the 16 anti-HCV-positive patients, HCV-RNA was detected in 5 (31%) with the NS3 primers and in 12 (75%) with 5'-noncoding primers. Among the anti-HCV-negative patients, HCV-RNA was detected in 2 (4.3%) of 47 patients. Eleven of the 18 patients with HCV infection (anti-HCV and/or HCV-RNA-positive) had evidence of additional present or past viral infections (human immunodeficiency virus and/or hepatitis B virus). In summary, HCV-RNA is present in at least 75% of anti-HCV-positive patients, suggesting that they may be infectious. The detection of HCV-RNA in anti-HCV-negative patients may indicate early or chronic HCV infection not detected by current antibody assays or the inability of these patients to mount or sustain a significant antibody response.

Adult↗
PubMed1993

Detection of hepatitis C virus antibody by first and second generation assays and polymerase chain reaction in patients with autoimmune chronic active hepatitis types I, II, and III.

In this study we have attempted to classify a group of North American patients with autoimmune chronic hepatitis into types I, II, and III according to the class of autoantibody present in serum, and determine the prevalence and significance of antibody to hepatitis C virus (anti-HCV). A total of 62 patients (type I, 51; type II, 3; type III, 8) were tested with first-generation enzyme-linked immunosorbent assay (ELISA)-1. Seropositive patients were assessed by second-generation recombinant immunoblot assay (RIBA)-2 and polymerase chain reaction (PCR). Our results demonstrate that 12 (19%) of the 62 patients with autoimmune hepatitis were anti-HCV ELISA-1 positive (type I, 9; type II, 1; type III, 2). Only one patient with type II autoimmune hepatitis was reactive by RIBA-2 and PCR. Eight of the 12 seropositive patients entered remission after corticosteroid therapy and seven of them became seronegative by ELISA-1. The RIBA-2 and PCR reactive patient did not respond to immunosuppressive therapy and remained seropositive. We conclude that there is a low prevalence of anti-HCV antibody in autoimmune hepatitis. Results based only on ELISA-1 anti-HCV testing can be misleading, and second-generation testing is necessary to recognize the presence of HCV infection. The fact that the only RIBA-2 reactive patient had type II autoimmune hepatitis may suggest a role for HCV infection in the pathogenesis of this condition. Nevertheless, corticosteroid therapy remains effective in those patients who are ELISA-1 seropositive, but RIBA-2 and PCR nonreactive.

Adolescent↗
PubMed1992

Antimitochondrial antibodies in kindreds of patients with primary biliary cirrhosis: antimitochondrial antibodies are unique to clinical disease and are absent in asymptomatic family members.

The 2-oxo-acid dehydrogenase family of enzymes have been identified as the major mitochondrial autoantigens of primary biliary cirrhosis. Using immunoblotting, enzyme-linked immunosorbent assay and enzyme inhibition with both purified mitochondrial proteins and recombinant autoantigens, we have studied family members and spouses of patients with primary biliary cirrhosis for the presence of antimitochondrial antibodies. Antimitochondrial antibodies and other common autoantigens were also tested for by indirect immunofluorescence. This study included 27 index patients with primary biliary cirrhosis, 15 spouses and 48 first- and second-degree relatives. Overall, 7 relatives (11%) were positive for autoantibodies to nuclear and cytoplasmic antigens by indirect immunofluorescence against mouse liver and stomach sections. However, with immunofluorescence, the reactivity strictly paralleled that of antimitochondrial antibodies in only one of these (1:640)--a sibling with mild pruritus and a liver biopsy specimen diagnostic of primary biliary cirrhosis despite normal levels of serum alkaline phosphatase. In addition, one of the mothers, who had a history of sarcoidosis, was positive by immunoblotting for antibodies to the E2 subunit of the pyruvate dehydrogenase complex and protein X. All other relatives were negative for all of the assays. Antibodies to neither the 2-oxo-acid dehydrogenase enzymes nor the recently proposed family of naturally occurring mitochondrial antibodies were found in spouses or healthy relatives. Three other first-degree relatives suffered from liver disease: two died (one from primary biliary cirrhosis and the other from an unknown type of liver disease) and one (a sibling with primary biliary cirrhosis) was unavailable for testing. Our results are consistent with a familial predisposition to primary biliary cirrhosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Improved detection of antibodies to hepatitis C virus in dialysis patients using a second-generation enzyme immunoassay.

We tested serum samples from 99 patients undergoing maintenance hemodialysis for hepatitis C virus (HCV) antibodies using a first-generation, licensed anti-HCV enzyme immunoassay (EIA) and a second-generation anti-HCV EIA that detect three gene products c100-3, NS3, and core. Specimens that were repeatedly reactive by either or both screening assays were further evaluated by testing with supplemental EIAs and a dot blot immunoassay. There was 87.9% agreement between the licensed HCV EIA and the HCV EIA second generation. HCV EIA Second Generation detected 10 more positive specimens than HCV EIA, for an increase in detection from 33.3% (33/99) to 43.4% (43/99). We conclude that HCV EIA Second Generation improves detection of HCV infection in hemodialysis patients.

Adult↗