Search PubMed⌕ Search

Biomedical subjects

G L Davis

Publications and source records attributed to G L Davis.

At least 91 records · Page 5Linked to original sources
PubMed1994

Detection of hepatitis C viral sequences in formalin-fixed, paraffin-embedded liver tissue: effect of interferon alpha therapy.

To determine the effect of interferon-alpha (IFN) therapy on hepatitis C virus (HCV) in liver, reverse transcription "nested" polymerase chain reaction (RT-PCR) was applied to detect HCV RNA in formalin-fixed, paraffin-embedded liver biopsy specimens obtained before and at the end of IFN therapy in 42 patients with chronic HCV infection. Results were correlated with the clinical and biochemical outcome in 36 cases. Fifteen patients were nonresponders to IFN; 13 patients had a complete response to IFN but relapsed shortly after IFN was stopped (responders who relapsed); and 8 patients showed a complete and sustained response to IFN therapy (sustained responders). Total RNA was extracted using proteinase K digestion and phenol/chloroform/isoamyl alcohol extraction, and HCV RNA was detected by standard RT-PCR using primers from the highly conserved 5' untranslated region. HCV RNA was detected in 41 of the 42 pretreatment specimens. Of the 36 patients with paired posttreatment samples, HCV RNA was detected in all 15 patients who did not respond to IFN and 9 of 13 who responded to IFN but relapsed shortly after IFN was stopped. In contrast, only one of the eight patients who had a sustained response to IFN therapy had HCV RNA detected by RT-PCR (P < 0.04). These data confirm 1) the feasibility of detecting HCV RNA in formalin-fixed, paraffin-embedded tissue from patients with chronic HCV infection, 2) show that sustained response to IFN is associated with loss of liver HCV RNA at the end of IFN therapy, and 3) offer an explanation for recurrence in patients who relapse.

Base Sequence↗
PubMed1994

Immunoglobulin M and A antibodies to hepatitis C core antigen in chronic hepatitis C virus infection.

To determine the prevalence and clinical significance of IgM and IgA antibody to hepatitis C virus (HCV) core antigen in chronic HCV infection, sera from 47 patients were tested for immunoglobulin class M (IgM) and immunoglobulin A (IgA) antibody to HCV core antigen by solid-phase enzyme-linked immunoassay using a recombinant core protein (aa1-150). Results were correlated with the clinical, biochemical and histological parameters, serum HCV RNA levels (determined by branched DNA signal amplification assay), and subsequent clinical response to interferon-alpha therapy. IgM anti-HCV core was detected in 11 patients (23.4 percent). There was no correlation between the presence of IgM anti-HCV core and the clinical features (sex, age, mode of acquisition), biochemical parameters (serum ALT, AST, alkaline phosphatase, and albumin level), autoimmune markers [serum globulin levels, anti-nuclear antibody (+ at < 1:80 in 7/47 patients)], serum HCV RNA levels, subsequent response to interferon-alpha therapy, and the histological features. Immunoglobulin A anti-HCV core was not detected in any of the patients. The presence of IgM ant-HCV core in a proportion of patients with chronic HCV infection indicates that the presence of serum IgM anti-HCV core may not be unique to acute HCV infection.

Adult↗
PubMed1994

Detection of hepatitis C virus genome in formalin-fixed paraffin-embedded liver tissue by in situ reverse transcription polymerase chain reaction.

Detection of hepatic hepatitis C virus RNA and antigens is difficult since their expression is very low. The technique of in situ reverse transcription polymerase chain reaction (IS-RT-PCR) was developed for the detection and localization of HCV RNA in formalin-fixed paraffin-embedded liver sections. Key steps for achieving a good signal-to-background ratio include appropriate proteolytic digestion, DNase pretreatment, higher Mg2+ concentration, primers from the core region, "hot-start", and between 10-20 cycles of PCR. Using this approach, HCV RNA was detected in the liver in four of the six patients. In those positive samples, the percentage of cells positive for HCV RNA ranges from < 5 to 25%. Using RT-PCR of serum samples and RNA extracted from the corresponding tissue block (10 sections) as the gold standard and sections from four control subjects as negative controls, the sensitivity and specificity of this assay was 4/6 and 4/4, respectively. The specific positive signal was found mainly in the cytoplasm of the hepatocytes and occasionally in mononuclear cells but not in the bile duct epithelium or sinusoidal cells. These positive hepatocytes were scattered in the liver lobules with occasional clustering. These preliminary data confirm the hepatotropic nature of HCV and the localization of HCV RNA is consistent with cytoplasmic replication.

Base Sequence↗
PubMed1994

Duplicate publication.

Explore the source record for details and available documents.

Duplicate Publications as Topic↗
PubMed1994

Cholestatic hepatitis leading to hepatic failure in a patient with organ-transmitted hepatitis C virus infection.

A 51-year-old heart transplant recipient who developed subfulminant hepatic failure because of organ-transmitted hepatitis C virus (HCV) infection is described. He presented with a predominantly cholestatic liver damage after heart transplantation. An extensive evaluation, including abdominal ultrasound and computed tomography scan and endoscopic retrograde cholangiopancreatography was unrevealing. Liver biopsy, however, was suggestive of a large duct obstruction with prominent portal and pericellular fibrosis, marked cholestasis, pericholangitis with marked ductular proliferation, and diffuse hepatocyte degeneration. Antibody to HCV (anti-HCV) was initially negative. He deteriorated in the ensuing 3 months. A repeat enzyme immunoassay-2 test for anti-HCV 4 months after initial presentation was weakly positive. Quantitation of serum HCV RNA by branched DNA assay revealed high level viremia, 547 x 10(6) genome equivalents per milliliter. Using in situ polymerase chain reaction, HCV RNA was detected in the cytoplasm in > 80% of the hepatocytes. The patient underwent interferon alfa therapy, and serum HCV RNA levels were reduced 20-fold after four doses. Unfortunately, the patient developed pulmonary aspergillosis and died. This case illustrates that in immunosuppressed patients anti-HCV is not a good marker for the diagnosis of HCV infection, and HCV can cause a progressive form of cholestatic liver disease mimicking a large duct obstruction.

Base Sequence↗
PubMed1994

Optimization for the detection of hepatitis C virus antigens in the liver.

To optimize the detection of hepatitis C viral antigens in liver tissue, cryostat and formalin-fixed, paraffin-embedded liver sections from 21 patients with chronic hepatic C viral infection were studied. For cryostat sections, six different fixatives were compared. Sixteen primary antibodies were tested: nine different mouse monoclonal anti-hepatitis C virus-core antibodies, a human monoclonal anti-hepatitis C virus-non-structural 4, and six rabbit polyclonals directed against synthetic peptides of the hepatitis C virus core, envelope, and non-structural 3, non-structural 4, non-structural 5. Three detection systems, 3- and 5-step peroxidase-antiperoxidase and avidin-biotin complex, were examined. In cryostat sections, acetone/chloroform formation consistently produced the best signal-to-background ratio. Five anti-hepatitis C virus-core monoclonals which recognize amino acid sequence 26-45 of the hepatitis C virus-core region consistently detected the viral antigen, but not the monoclonals directed against 39-74 of the hepatitis C virus-core region. The human anti-hepatitis C virus-non-structural 4, which reacts to amino acid sequence 1700-1705, also regularly detected viral antigen. The rabbit polyclonals produced either negative or nonspecific staining. The 5-step peroxidase-antiperoxidase provided the strongest signal and the avidin-biotin system produced high background consistently. Overall, hepatitis C virus core and non-structural 4 antigens were detected in 71% and 57% of the patients studied. Of the 16 patients seropositive for hepatitis C virus RNA, 75% and 69% had detectable hepatitis C virus core and non-structural 4, in contrast to 60% and 20% of the five hepatitis C virus RNA seronegative patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Viral↗
PubMed1994

Clinical predictors of response to recombinant interferon-alpha treatment in patients with chronic non-A, non-B hepatitis (hepatitis C). The Hepatitis Interventional Therapy Group.

Chronic non-A, non-B hepatitis (NANBH) is a common and often progressive liver disease. Based on current serological tests, hepatitis C virus (HCV) infection is responsible for most cases. Interferon-alpha (IFN) treatment at a dose of 3 x 10(6) units given three times per week for 24 weeks has been shown to be effective in normalizing serum alanine aminotransferase (ALT) levels and reducing hepatic inflammation in approximately 40% of these patients. The purpose of this study was to identify pretreatment characteristics in patients with chronic hepatitis C(CH-C) which would best predict a favourable response to IFN treatment (normalization of serum ALT). One hundred and sixty-three adult patients who had participated in a large multicentre treatment trial were included in the study group; 84 had been treated with 3 x 10(6) units of recombinant IFN-alpha-2b (rIFN) subcutaneously three times per week for 24 weeks and 79 patients had been treated with 1 x 10(6) units rIFN in the same dosage schedule. Forty-one pretreatment historical, clinical, laboratory and histological variables were evaluated. In addition, early biochemical improvement during treatment was evaluated as a predictor of ultimate response. Univariate analysis identified six variables (dose, dose m-2, weight, body surface area, ongoing ethanol use, white blood cell count and the presence of symptoms) as potential predictors of response (two-tailed, P < 0.15). By multivariate analysis, however, only the 3 x 10(6) dose of rIFN was independently predictive of response (P < 0.01). When the analysis of response was confined to those patients who received treatment with 3 x 10(6) units of rIFN, seven variables [body weight, surface area, dose m-2, current ethanol use, serum albumin and the presence of chronic persistent hepatitis (CPH) on entry liver biopsy] were more frequent in patients who responded to therapy. In a multivariate model, only CPH and body weight predicted an increased likelihood of response (P < 0.01). However, the model was not a sensitive predictor of response as only 18% of the study group had CPH on liver biopsy. A decrease in serum ALT levels within the first 12-16 weeks of rIFN treatment was found to be the strongest indicator of an ultimate response to treatment. Thus, assessment of early response to IFN treatment is the only practical means of predicting complete response and avoiding prolonged and unnecessary therapy in those with little chance of response.

Adult↗
PubMed1994

Therapy for chronic hepatitis C.

Hepatitis C is the silent epidemic of the 1970s and 1980s. Interferon alfa is currently the only effective treatment. Enthusiasm for interferon therapy must be tempered because advanced disease usually requires years or even decades to develop and does not occur in all patients. Few patients with chronic hepatitis C derive long-term improvement from a single 6-month course of interferon therapy. Most initial responders relapse and require long-term interferon treatment to suppress the virus. Obviously, the initial goals and expectations for interferon therapy require rethinking. Therapy should not be undertaken by physician or patient with the idea that therapy will be limited to 6 months. The most appropriate goal of therapy now appears to be the long-term control of the biochemical, virologic, and histologic activity of the disease. Unfortunately, the most effective therapeutic regimen for achieving this goal is not yet known and will require continued clinical research.

Chronic Disease↗
PubMed1994

Quantitative detection of hepatitis C virus RNA with a solid-phase signal amplification method: definition of optimal conditions for specimen collection and clinical application in interferon-treated patients.

To determine the optimal conditions for preparation of serum specimens for quantitative hepatitis C virus RNA determination, patient samples were processed such that differences in time from clot formation to centrifugation, centrifugation to separation of serum and collection of serum until freezing could be independently assessed. The effects of multiple cycles of freezing and thawing were also determined. There was progressive and significant loss of hepatitis C virus RNA activity when the time from the formation of the clot until centrifugation was longer than 2 hr. This reduction reached 32% after 6 hr and 49% after 24 hr. If centrifugation was performed immediately after formation of the clot, loss of hepatitis C virus RNA activity was reduced to less than 10% even though the serum remained unseparated from the clot for up to 6 hr. Centrifugation of blood through a paraffin plug (serum separator tube) prevented loss of hepatitis C virus RNA activity for up to 24 hr. There was no loss of hepatitis C virus RNA activity with up to three freeze-thaw cycles. When patient specimens were prepared under these optimal conditions, the sensitivity of the quantitative branched DNA signal amplification assay in patients with hepatitis C virus infection was 83% and the specificity in patients with liver disease was 100%. Fluctuations in hepatitis C virus RNA levels were shown to correlate with biochemical changes observed in patients treated with recombinant interferon-alpha 2b. These data demonstrate that improper or inconsistent methods of serum preparation may result in falsely low and unreliable levels of hepatitis C virus RNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine Transaminase↗
PubMed1993

Discrepancy between biochemical and virological responses to interferon-alpha in chronic hepatitis C.

Serial serum samples and pretreatment and post-treatment liver tissue from patients with chronic hepatitis C virus (HCV) infection were tested for HCV RNA by reverse-transcription polymerase chain reaction and branched DNA signal amplification assays. At the end of treatment with interferon-alpha (IFN alpha), 4 of 5 patients showing no biochemical response (in alanine aminotransferase activity), 4 of 5 with transient responses, and 1 of 5 showing complete and sustained responses had HCV RNA detectable in serum. The corresponding numbers for liver tissue were 5, 5, and 0 (of 4). However, all 5 complete responders had virological relapses within 6 months. Biochemical response may not reflect virological profile during IFN alpha treatment of HCV.

Adult↗
PubMed1993

Significance of serum hepatitis C virus RNA levels in chronic hepatitis C.

Hepatitis C virus (HCV) is the main cause of parenteral non-A, non-B hepatitis and serum can be tested for the virus itself by reverse-transcription polymerase chain amplification. What of the level of this viraemia? To find out if quantitative study of HCV RNA might be useful clinically we took advantage of participation in trials of interferon-alpha in patients with chronic HCV infection and applied a new assay, branched DNA (bDNA) signal amplification. Paired serum and liver biopsy specimens from 47 patients with confirmed chronic HCV infection and evidence of HCV RNA in their serum were studied. The quantitative bDNA assay (detection limit 350,000 equivalents/mL [eq/mL]) was positive in 34 sera (sensitivity 72%). Patients who acquired HCV infection by blood transfusion had a higher viraemia (median 2,701,000 eq/mL, n = 29) than health workers and intravenous drug users (635,000 eq/mL, n = 13; p < 0.01). Patients with a sustained complete response to interferon-alpha therapy had lower pre-treatment viraemia levels (median at bDNA cut-off, n = 11) than complete responders who relapsed after the drug was stopped (1,613,000 eq/mL, n = 15; p < 0.01) and non-responders (3,066,000 eq/mL, n = 20; p < 0.01). High viraemia levels were not related to the histological diagnosis but were associated with lobular inflammation, lymphoid aggregates, and bile-duct lesions. These findings indicate that mode of acquisition is an important determinant of HCV viraemia and that patients with low HCV viraemia levels are more likely to respond to interferon in a sustained fashion.

Adult↗