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Biomedical subjects

M Houghton

Publications and source records attributed to M Houghton.

At least 91 records · Page 5Linked to original sources
PubMed1992

Enhanced sensitivity of a second generation ELISA for antibody to hepatitis C virus.

A second generation ELISA for combined detection of antibodies to three hepatitis C virus (HCV) recombinant proteins, i.e. C100, C33c and core, was compared with a first generation anti-HCV ELISA in which only antibodies to C100 are detected. The results of the ELISAs were evaluated in 225 haemophilia patients (panel A) and 44 patients with non-A, non-B (NANB) hepatitis (panel B). HCV infection was established by cDNA-polymerase chain reaction (PCR) (in panel B only) and by studying the anti-HCV reaction patterns in 4 separate ELISAs for detection of antibodies to the recombinant proteins C100, C33c, core and a combination of two synthetic peptides sp67/65 derived from the C100 region. The sensitivity for the detection of HCV infection had increased from 0.92[95% confidence interval (CI): 0.87-0.95] to 1.00 (95% CI: 0.89-1.00) in haemophiliacs and from 0.84 (95% CI: 0.66-0.95) to 1.00 (95% CI: 0.89-1.00) in NANB hepatitis patients when the second generation ELISA was used instead of the first generation ELISA. Concurrently the chance of a false negative result was reduced in panel A and B from 0.37 to 0 and from 0.28 to 0, respectively. Analysis of anti-HCV reaction patterns revealed that 172 of 206 (83.5%) anti-HCV ELISA-reactive haemophilia patients had antibodies to all 4 antigens tested. In the NANB hepatitis patients 18 of 31 (58.1%) anti-HCV ELISA-reactive subjects reacted with 4 antigens. In the PCR tested panel of NANB hepatitis patients 2 subjects who showed antibody reactivity to only one antigen and 5 patients with reactivity to 2 antigens were PCR-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Viral↗
PubMed1992

Hearing loss prevalence and management in nursing home residents.

OBJECTIVES: To determine the prevalence and management of hearing loss and hearing handicap among non-demented nursing home residents. DESIGN: Descriptive study of total population of two nursing homes. PARTICIPANTS: All 121 eligible residents. SETTINGS: Two nursing homes. MINI OUTCOME MEASURES: Audiometry, questionnaires of nurses and subjects regarding perceived hearing handicap, and documentation in medical records of hearing loss. RESULTS: 77% had at least a mild (greater than or equal to 26 dB Hearing Level) hearing loss in the better ear, and 51% had a moderate to severe loss (greater than or equal to 41 dB HL). Self-assessments of hearing handicap by residents, together with audiometric findings and expressed interest in a hearing aid, were more useful guides for aural rehabilitation needs than were nurses' assessments of residents' handicaps. Medical records failed to identify 48% of residents with moderate to severe hearing losses. Fifty-eight percent of residents with severe hearing loss currently had hearing aids, and 38% more would like to have an aid. CONCLUSIONS: Residents should have hearing evaluations with documentation of results on admission and periodically under the direction of a nurse trained as a hearing specialist. Environmental modifications of the NH plus use of hearing aids can improve hearing.

Aged↗
PubMed1992

Storage conditions of blood samples and primer selection affect the yield of cDNA polymerase chain reaction products of hepatitis C virus.

We have noticed that suboptimal specimen processing and storage conditions may cause false-negative results in the detection of hepatitis C virus (HCV) RNA in plasma or serum. To establish the influence of specimen handling in a serological laboratory on the rate of detection of HCV RNA by the cDNA polymerase chain reaction (cDNA-PCR), we tested routine serum samples and fresh-frozen plasma samples from the same bleeding from confirmed anti-HCV-positive blood donors. When primers from the NS3/NS4 region were used, HCV RNA was detected in fresh-frozen plasma from 67% of the donors, whereas positive results were obtained with only 50% of the serum samples that had been subjected to routine serological procedures. Analysis of the same samples with primers from the highly conserved 5'-terminal region (5'-TR) revealed an HCV RNA detection rate of 92% for both the routine and the fresh-frozen samples. However, the yield of the amplification product in routine samples was strongly reduced compared with that in fresh-frozen plasma. Comparison of both primer sets for cDNA-PCR showed that the 5'-TR primer set was 10- to 100-fold more effective in detecting HCV RNA. We also analyzed the effect of storage of whole EDTA-blood and serum at room temperature and at 4 degrees C on the yield of the amplification product. A rapid decline in detectable HCV RNA of 3 to 4 log units was observed within 14 days when whole blood and serum were stored at room temperature. By contrast, no perceptible reduction in the cDNA-PCR signal was found in freshly prepared serum stored at 4 degrees C.

Base Sequence↗
PubMed1992

Disappearance of hepatitis C virus RNA in plasma during interferon alpha-2B treatment in hemophilia patients.

To establish the effect of interferon alpha-2B (IFN-alpha) treatment on hepatitis C virus (HCV) viremia, rather than monitor the alanine aminotransferase (ALAT) values we measured HCV-RNA by cDNA-polymerase chain reaction (cDNA-PCR) in plasma before and during IFN-alpha treatment. Eight hemophilia patients with chronic hepatitis C were treated with IFN-alpha for 24 weeks: 5 MU daily for 2 weeks, 2.5 MU daily for 4 weeks, and 1.5 MU three times a week for 18 weeks. HCV-RNA, as measured by cDNA-PCR, was present in all patients before treatment. After 24 weeks of treatment HCV-RNA was no longer detectable in three of eight (37.5%) patients, whereas only one of eight (12.5%) patients showed complete ALAT normalization. In three of eight patients a transient response to IFN-alpha was seen, with renewed HCV-RNA detection after dose reduction. HCV-RNA measurement by cDNA-PCR appeared to be more sensitive in detecting relapse than ALAT measurement.

Alanine Transaminase↗
PubMed1991

Vertical transmission of hepatitis C virus.

There is evidence that hepatitis C virus (HCV) may be vertically transmitted from infected mothers to their children. To test this hypothesis, we prospectively studied 10 pregnant women at high risk from parenterally or sexually transmitted diseases with the polymerase chain reaction. HCV RNA was found in 8 newborn babies delivered by women who were anti-HCV seropositive, and persisted for 2-19 months of follow-up. Anti-HCV detected in 7 infants cleared by 9 months and remained undetectable thereafter. Serum alanine aminotransferase was raised in 3 infants. The findings provide evidence of vertical transmission of HCV and suggest that perinatal infection may initiate a silent disease process or chronic carrier state.

Alanine Transaminase↗
PubMed1991

Characterization of the terminal regions of hepatitis C viral RNA: identification of conserved sequences in the 5' untranslated region and poly(A) tails at the 3' end.

We have determined the nucleotide sequence at the extreme 5' and 3' termini of the hepatitis C virus (HCV) genome. Our analyses of these sequences show (i) the nucleotide sequence in the 5' untranslated region is highly conserved among HCV isolates of widely varying geographical origin, (ii) within this region, there are blocks of nucleotide sequence homology with pestiviruses but not with other viruses, (iii) the relative position of short open reading frames present in the same region of the HCV genome is similar to that of the pestiviral genome, (iv) RNAs truncated at the 5' and 3' ends are found, but the origin and functions of these RNAs are unknown, and (v) poly(A) tails appear to be present on 3' subgenomic RNAs. These data differentiate HCV from the flaviviruses and indicate a closer evolutionary relationship of HCV with the pestiviruses. However, HCV also appears to be substantially different from other known pestiviruses. These data are consistent with the assignment of HCV to a separate viral genus.

Amino Acid Sequence↗
PubMed1991

Hepatitis C antibody in patients with chronic liver disease and hepatocellular carcinoma.

Hepatitis C virus (HCV) is the major etiologic agent of parenterally transmitted non-A, non-B hepatitis. To determine whether there is a relationship between this virus agent and hepatocellular carcinoma (HCC), the sera of patients with HCC and chronic hepatitis were assessed using a sensitive immunoassay for HCV antibody. Anti-HCV was detected in 65% of 132 patients with HCC, without any relationship with the presence of the hepatitis B surface antigen (HBsAg). The prevalence (74%) of anti-HCV was high, as expected in patients with putative non-A, non-B cirrhosis also. The prevalence of anti-HCV was less in patients with HBsAg-positive cirrhosis (28%) and in patients with disease not related to viral hepatitis and healthy controls (8%). These data suggest, but do not prove, that HCV is an important factor associated with HCC.

Carcinoma, Hepatocellular↗
PubMed1991

Hepatitis C virus antibodies in acute icteric and chronic non-A, non-B hepatitis.

Hepatitis C virus antibodies were measured in 213 patients who had acute (n = 122) and chronic (n = 91) non-A, non-B hepatitis. In acute infection, anti-hepatitis C virus was detected in 61% of IV drug abusers, in 33% of patients with transfusion-associated hepatitis, and in 22% of patients with sporadic infections (P less than 0.0005, drug abusers vs. sporadic). Mean time to seroconversion was 11.6 weeks (range, 1-80 weeks). Anti-hepatitis C virus was more common in chronic infection (P less than 0.001) and was more often detected in IV drug users (89%; P less than 0.0001) and after transfusion (71%; P less than 0.005) compared with chronic sporadic infection (27%). Antibody persisted for up to 8 years. Six chronic case patients (8.3%) later lost antibody (mean, 24 months; range, 12-48 months).

Acute Disease↗
PubMed1991

Variable and hypervariable domains are found in the regions of HCV corresponding to the flavivirus envelope and NS1 proteins and the pestivirus envelope glycoproteins.

Based on the flavi- and pestivirus model of genome organization for the hepatitis C virus (HCV) (1-5), the nucleotide and deduced amino acid sequences of the putative envelope (E1) and the junction between the E1 and NS1/envelope 2 (E2) region from six different human isolates of HCV were compared with the nucleotide and predicted amino acid sequences of the prototype hepatitis C virus (HCV-1) (5). The overall percentage of nucleotide and amino acid changes among all six isolates, including HCV-1, from nucleotide 713 to 1630 (amino acid 129 to 437) was between 3 and 7%, which is comparable to that seen in some flaviviruses (6-8). An analysis of the number of nucleotide and deduced amino acid sequence changes among all six isolates and HCV-1 revealed a moderately variable domain of approximately 40 amino acids in the E1 region and a hypervariable domain (Region V) of approximately 28 amino acids, which is directly downstream from a putative signal peptide sequence, in the junction between E1 and NS1/E2. A similar hypervariable domain is not found in the C-terminus of the envelope polypeptide or in the N-terminus of the NS1 polypeptide domain of the flaviviruses. These findings suggest that the mature NS1/E2 polypeptide starts about amino acid 380 and that the NS1/E2 domain may correspond to a second envelope glycoprotein as in the case of the pestivirus. The observed heterogeneity in the putative structural proteins of HCV may have important ramifications for future vaccine development.

Amino Acid Sequence↗
PubMed1991

Analysis of genomic variability of hepatitis C virus.

The anti-C100-enzyme-linked immunosorbent assay, the new four-antigen antibody recombinant immunoblot assay, and detection of viral RNA sequences by copy DNA-polymerase chain reaction were used to establish the course of hepatitis C virus (HCV) infection in recipients of HCV-infected blood products. Different patterns of infection were observed: (1) persistent HCV infection with and without chronic hepatitis, and with acute resolved hepatitis; and (2) acute resolved hepatitis with clearance of HCV. In order to determine whether different infection- and anti-HCV recognition patterns are correlated to differences in viral nucleotide sequences, we compared sequences in the NS3 region between isolates from recipient(s) and their infective donors. Based on these comparisons we conclude that in The Netherlands two types of molecular variants circulate; one resembling the Japanese prototype isolate JH1, and the other the HCV-1 isolate from the U.S.A. The difference in sequence homology between the two types is approximately 24%. Comparison of sequences of donors and involved recipients determined in isolates prepared from blood samples four years after transfusion revealed that viral RNA sequences are strongly conserved (greater than 96.8%) in the NS3 region. These data indicate that the observed differences in anti-HCV immune response patterns between recipients are more a reflection of their immune reactivity than of divergence of viral strains.

Cardiac Surgical Procedures↗
PubMed1991

Rabbit-derived anti-HD antibodies for HDAg immunoblotting.

We studied the sensitivity and specificity of two rabbit-derived antibodies (W2 and W3) raised against two synthetic peptides of the HDAg: the C-terminus of the p24 protein (W2) and the C-terminus of the p27 protein (W3) (Chiron Co., Emeryville, CA, U.S.A.). The results were compared with those obtained with a human polyclonal anti-HD (W1). We have tested W2 and W3 against blotted serum samples from 25 patients (20 HBsAg positive anti-HD positive, three HBsAg positive anti-HD negative and two HBsAg negative anti-HD negative) and liver extracts from five HBsAg seropositive patients, two anti-HD positive and three anti-HD negative. In serum samples W3 sporadically reacted with a p31 protein present in both anti-HD positive and negative sera; W2 identified the p24 protein in 7/10 W1 positive samples but in none of 10 W1 negative; the p27 protein was captured by W2 only in one highly viremic serum. In every sample of liver extract W3 recognized a 48-kDa band. W1 and W2 stained 5 bands at 45, 27, 24, 16 and 12 kDa. The p45, p27 and p24 proteins were peculiar of HDV-infected livers; p16 and p12 were also detected in HDV free livers. W2 identified an additional 54-kDa protein in 4/5 liver extracts. For diagnostic purposes human polyclonal anti-HD represents the most sensitive probe for HDAg immunoblotting, with a specificity similar to that of rabbit-derived antibodies. The affinity of W2 and W3 antibodies for serum and liver HDAg appears to be lower than for HDAg recombinant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Use of a signature nucleotide sequence of hepatitis C virus for detection of viral RNA in human serum and plasma.

The nucleic acid sequence of the putative 5'-untranslated (5PUT) region of hepatitis C virus (HCV), determined for samples obtained from a variety of geographic origins, was found to be over 98% conserved among all isolates. On the basis of this signature sequence for HCV, a viral RNA assay was developed by using cDNA synthesis with reverse transcriptase, followed by polymerase chain reaction (PCR). The new assay was compared with the Ortho-Chiron C100-3 HCV enzyme-linked immunosorbent assay to research radioimmunoassays for antibodies to the C33c and C22 HCV antigens and to the first reported set of HCV PCR primers designed from the NS3 domain. Plasma samples from 16 Japanese patients with non-A, non-B hepatitis (NANBH) and 16 immunoassay-positive blood donors from the United States were investigated. The 5PUT PCR primers were found to be superior to the NS3 primers in sensitivity and specificity (15 of 25 versus 3 of 25 of the C100 enzyme-linked immunosorbent assay-positive samples, respectively). Samples from two C100-negative patients with acute NANBH were found to react with the 5PUT primers but not with the NS3 primers. Also, two of three patients with chronic NANBH converted from reverse transcriptase PCR positive to negative after interferon treatment. Although the clinical significance of the presence or absence of HCV RNA in samples from patients is not fully understood, the use of probes and primers from the 5PUT region (as opposed to primers from other segments) should not lead to false-negative results due to nucleic acid sequence variations in viral isolates.

Base Sequence↗
PubMed1991

Role of hepatitis C virus in non-B chronic liver disease.

To assess the contribution of the recently identified hepatitis C virus to chronic liver diseases of unknown cause and chronic hepatitis attributed by exclusion to non-A, non-B hepatitis, we tested for antibody to hepatitis C in hepatitis B surface antigen-negative patients with a spectrum of chronic liver diseases. Antibody to hepatitis C virus, a marker of hepatitis C infection, was detected with a first-generation radioimmunoassay at the following frequencies in the following patient groups: 69% of transfusion-associated non-A, non-B hepatitis; 53% of non-transfusion-associated non-A, non-B hepatitis; 26% of hepatitis B surface antigen-negative hepatocellular carcinoma; 8% of cryptogenic cirrhosis; 5% to 7% of autoimmune chronic liver diseases; 19% of patients with miscellaneous types of chronic liver disease; and 0.67% of healthy controls. Among non-transfusion-associated cases, 81% with a history of intravenous drug use but only 18% with occupational exposure as health workers had antibody to hepatitis C virus. Among cases of hepatocellular carcinoma, 63% of Japanese patients but only 11% of American patients had evidence of hepatitis C infection. Comparison in a subgroup of 79 serum samples of a second-generation radioimmunoassay with the first-generation assay demonstrated a 12% increase in antibody frequency from 30% to 42%. We conclude that hepatitis C plays a substantial role in transfusion-associated and non-transfusion-associated non-A, non-B hepatitis as well as in hepatocellular carcinoma, especially in Japan, a limited role in cryptogenic cirrhosis, and essentially no role in autoimmune chronic liver diseases. Application of more sensitive immunoassays will increase the frequency of antibody seropositivity in all subgroups, but relative distinctions among risk groups are likely to remain.

Asian↗
PubMed1991

The role of chronic viral hepatitis in hepatocellular carcinoma in the United States.

Although hepatocellular carcinoma is a relatively uncommon tumor in the United States, it is quite common in sub-Saharan Africa and the Far East, where most cases are associated with infection with the hepatitis B virus. We have studied 99 American patients with hepatocellular carcinoma for evidence of hepatitis B or hepatitis C viral infection and compared these findings to those in a group of matched controls with other cancers. The two groups differed in proportion, with hepatitis B surface antigen in serum being significantly higher in patients with hepatocellular carcinoma (7% vs. 0%, p = 0.009). Antibody to hepatitis C virus was also found more frequently in patients with hepatocellular carcinoma (13% vs. 2%, p = 0.002). The relative risk for hepatocellular carcinoma in hepatitis B surface antigen-positive patients was calculated to be 17.3 and for antibody to hepatitis C virus to be 7.3. The attributable fraction of cases related to the hepatitis B surface antigen carrier state was 6.7% and for patients infected with the hepatitis C virus was 11.4%. Approximately three quarters of cases of hepatocellular carcinoma did not have evidence of either hepatitis C or hepatitis B virus infection. These findings provide strong evidence that hepatitis C virus infection is associated with the development of hepatocellular carcinoma, and in the United States may even play a more important role than the hepatitis B virus.

Adolescent↗