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Biomedical subjects

M C Bernal

Publications and source records attributed to M C Bernal.

At least 19 recordsLinked to original sources
PubMed2001

Time estimation and aging: a comparison between young and elderly adults.

Studies about effects of aging on the estimation of short temporal intervals are not conclusive. The aim of the present research was to evaluate age-related differences in the reproduction of a short interval (10 s) using a computerized method. The sample comprised thirteen young adults (M = 26.15 years) and twelve elderly adults (M= 79.1 years). Three parameters of time estimation were measured: estimated time, absolute error, and standard deviation. Results showed that time estimates performed by elderly participants were shorter than those of younger ones, although there were no significant differences between the two age groups in the percentage of absolute errors or standard deviations. These findings could be explained by changes in the rate of the internal clock or to an interaction between more general changes in cognitive processes.

Adult↗
PubMed2000

Genomic variability of hepatitis G virus/GBV-C at the NS3 region: clinical implications.

A new hepatitis virus, named GBV-C or hepatitis G virus (HGV), closely related to the hepatitis C virus (HCV), was identified in 1994. The existence of quasispecies in HCV is very important. In this work polymerase chain reaction amplification of the NS3 region of the genome of GBV-C/HGV and heteroduplex mobility assay (HMA) were combined to investigate the presence of quasispecies in patients with chronic infection by GBV-C/HGV. Patients with chronic infection by HCV were used to validate the method. The HMA was also used to investigate the similarity between the cited genomic region of GBV-C/HGV in different infected patients. A high degree of heterogeneity was found for HGV existing as quasispecies and as differences between samples. This is of extreme importance because of the intrinsic clinical and pathogenic implications of quasispecies of a virus capable of producing disease, and is in accord with other studies which report on the genomic variability of the NS3 region.

Antiviral Agents↗
PubMed2000

Detection of HCV and GBV-CHGV RNA in peripheral blood mononuclear cells of patients with chronic type C hepatitis.

Hepatitis C virus (HCV) and hepatitis G virus (HGV) viraemia were investigated by RT-PCR protocols in peripheral blood mononuclear cells (PBMC) of 22 patients with chronic type C hepatitis. Samplings were at basal and 4-8 months after a 12 month period of treatment with interferon-alpha. A plus strand of HCV in PBMC was detected in 8 of 21 patients (38%) (p <0.05; chi2 test) with a lack of response to therapy; a minus strand was detected in 10% of chronic type C hepatitis and 25% of the patients harboured HCV RNA in PBMC. The association with a response was nearly significant (p <0.1; chi2 test). GBV-C/HGV RNA was detected in the serum of 9 of 21 (43%) patients and in PBMC of 20% of the patients viraemic. Genomic sequences of GBVC/HGV in PBMC were found, but further investigation is needed to assess the findings reported for HCV.

Flaviviridae↗
PubMed1999

Previous training in the water maze: differential effects in NMRI and C57BL mice.

It has been shown that acquisition rates in the water maze vary across strains of mice, although the differential effects of previous experience in this spatial task have been scarcely evaluated. The aim of the present study was to evaluate the effects of training in the water maze at an early age (2 months) in two strains of mice (NMRI and C57BL) using a longitudinal study. Mice with or without previous training were tested when they were 6 months, and retested when 10 months old. The results showed that trained NMRI mice performed better than all the other groups, both at test and retest, indicating that previous training had more beneficial effects in NMRI than in C57BL mice. These results demonstrate that the effects of an early training in the water maze may be influenced by the characteristics of the strain of mice. It could have implications in longitudinal studies evaluating effects of pharmacological or behavioral manipulations.

Age Factors↗
PubMed1999

Effects of nicotine on spatial learning in C57BL mice.

In the present study, the effects of nicotine on spatial memory in C57BL/6J mice was evaluated. Mice were trained in a water maze during four daily sessions of three trials each. In the first experiment, nicotine (0.7 and 0.35 mg/kg) or saline was administered once daily for 4 days, 15 min before the start of daily training: an impairment of performance of the water maze was observed in the group treated with 0.7 mg/kg of nicotine. In the second experiment, nicotine (0.7 and 0.35 mg/kg) or saline was administered from the 5 days prior to the beginning of the task and during the 4 days of acquisition. The results indicated an improvement in the rate of learning in the 9-day nicotine treated groups. The comparison between 4-day and 9-day treated groups revealed that the group receiving 0.35 mg/kg of nicotine for 9 days displayed significantly shorter latencies than all the other groups, while the group receiving 0.7 mg/kg of nicotine for 4 days performed significantly worse than all the other groups. The most noteworthy result is that nicotine was more effective after a more prolonged administration than when administered only during the training days.

Animals↗
PubMed1998

Subtype distribution among intravenous drug users with chronic type C hepatitis in southern Spain.

The hepatitis C virus (HCV) subtype distribution among intravenous drug users (IVDU), and patients without this risk of acquiring HCV infection, was evaluated. The patients included in the study were 51 with chronic type C hepatitis (36 IVDU and 25 coinfected by HIV-1), and 31 on haemodialysis. Genotyping was performed on 71 viraemic patients, with the following distribution: 25.4%, 1a; 54.9%, 1b; 8.5%, 3a; 7%, mixed (1a, 1b; 3a, 1a; 3a, 1b; 2 x 3a, 2a); 1.4%, 4; and 2.8%, non-typeable. When subtypes were related to IVDU practice, the statistical significance was p < 0.01 for subtypes 1a (48.5% vs 7.5%, for IVDU and non-IVDU, respectively) and 1b (16.1% vs 85.1%). No relation between HIV-1 coinfection and subtype distribution was observed among IVDU patients. The results suggest that among young IVDU of Southern Spain the emerging HCV subtype is 1a.

Antibodies, Viral↗
PubMed1996

Relationship between viral genotype and viral load in patients with chronic hepatitis C.

To determine the distribution of hepatitis C virus (HCV) genotypes and to related genotype to viral load, genotyping and quantification of viral RNA were carried out in 35 patients with chronic hepatitis C. Subtype 1a was most prevalent (43%), followed by subtypes 1b (23%) and 3a (14%). Mean viral load (log HCV-RNA copies/ml) for subtypes 1b, 1a and 3a was 7.1 +/- 1, 5.6 +/- 1.1 and 4.1 +/- 2.4, respectively. The presence of immunoglobulin M was related to the duration of hepatitis and genotype 1 to a more severe hepatic injury and higher viral load. Differences observed in viral load for a single HCV subtype justify the need to quantify HCV-RNA prior to establishing antiviral therapy.

Analysis of Variance↗
PubMed1995

Seroepidemiological study of hepatitis E virus in different population groups.

In order to determine the seroprevalence of hepatitis E virus, 1,993 sera (453 from healthy pregnant women, 491 from Moroccan subjects, 492 from blood donors, 321 from children, and 236 from intravenous drug users) were studied. IgG was measured by enzyme immunoassay (EIA), and positive results were confirmed by Western blot. The EIA detected antibodies in 3.96% of the subjects (5.6% of the Moroccans and drug users and 1.8% of the children). Fifty-four percent of these results were confirmed by Western blot, 11.4% were found to be negative, and 34.2% indeterminate. The overall prevalence after confirmation by Western blot decreased to 2.15%. When studying the Western blot pattern of the positive samples, 95% showed antibodies to SG-3, 65% to 8-5, and only 9.3% to CKS fusion protein. In the indeterminate Western blots, the results for these proteins were 96.3%, 62.9%, and 37%, respectively. When the epidemiological data were analysed, no statistically significant differences between women and men or between different age groups were found.

Adult↗
PubMed1995

Human immunodeficiency virus type-1 can be detected in monocytes by polymerase chain reaction.

Lymphocytes and monocytes from 25 patients infected with human immunodeficiency virus type-1 (HIV-1)--13 asymptomatic, seven with the AIDS-related complex (ARC) and five with the acquired immunodeficiency syndrome (AIDS)--were lysed and subjected to PCR with three primer pairs: SK38/SK39 (gag), SK68/SK69 (env) and SK29/SK30 (LTR). Amplified DNA was solution-hybridised with 32P-labelled probes (SK19, SK70 and SK31, respectively) and detected by PAGE-autoradiography. HIV-1 DNA was detected as follows. Asymptomatic patients: monocytes--gag 61.5%, env 100%, LTR 0%; lymphocytes--gag 100%, env 92.3%, LTR 53.84%. ARC patients: monocytes--gag 71.4%, env 57.1%, LTR 0%; lymphocytes--gag 100%, env 71.4%, LTR 71.4%. AIDS patients: monocytes--gag 80.0%, env 100%, LTR 0%; lymphocytes--gag 100%, env 60%, LTR 60%. The presence of HIV-1 DNA was confirmed in the monocyte fraction. In this cell subset, the env gene-directed primers were the most effective for amplification, whereas the LTR gene-directed primers failed to amplify HIV-1 DNA. The different pattern of amplification found in monocytes may suggest that these cells could be infected by a genetic variant of the virus.

AIDS-Related Complex↗
PubMed1995

Evaluation of enzyme immunoassay for hepatitis B virus DNA based on anti-double-stranded DNA.

We have evaluated a new enzyme immunoassay technology to detect the products of PCR-based amplification that may be applicable to routine testing of hepatitis B virus (HBV) DNA. Two hundred eight serum samples were studied: 73 were basal samples and 135 were sequential serum samples from patients with chronic hepatitis, some of whom were being treated with alpha interferon. We compared the new detection method (PCR-DNA enzyme immunoassay [DEIA]) with dot blot hybridization performed without prior PCR amplification and with two other methods for detection of PCR products: agarose gel electrophoresis with ethidium bromide staining (PCR-EB) and dot blot (PCR-dot blot). For hepatitis B-antigen-positive basal samples, HBV DNA was detected in 70.4% by dot blot, 74.1% by PCR-EB, and 100% by PCR-DEIA and PCR-dot blot; for anti-hepatitis B e-antigen basal samples, HBV DNA was found in 10.5% by dot blot and PCR-EB and in 42.1% by PCR-DEIA and PCR-dot blot. Chi-square tests showed a strong association between dot blot and PCR-EB and between PCR-DEIA and PCR dot blot. Using PCR-dot blot as the reference, dot blot shows a 56.9% sensitivity and a 100% specificity, PCR-EB shows a 55.0% sensitivity and a 100% specificity, and PCR-DEIA shows a 95.4% sensitivity and a 97% specificity. We conclude that the technical advantages of the DEIA method and its high sensitivity and specificity may facilitate the use of PCR in routine testing for HBV DNA in clinical microbiology laboratories.

Base Sequence↗
PubMed1994

Helicobacter pylori seroepidemiology in risk groups.

Helicobacter pylori is associated with peptic ulcer and chronic active gastritis. The response to infection can be determined by measuring serum titers of anti-H. pylori antibodies. We compared antibody titers in 612 serum samples from 570 individuals considered at risk for H. pylori infection, 170 of them are control sera from 110 adults and 60 children with no gastric alterations. The study groups were 93 institutionalized mentally handicapped children, 40 heterosexual couples, 101 HIV-sero-positive patients, 86 patients with chronic renal failure and 40 individuals (20 adults and 20 children) with symptoms associated with gastritis or gastroduodenal ulcer disease. In the adult and child control groups, 33.5% and 11.6% of the individuals had circulating anti-H. pylori antibodies. Significantly more adults (80%) and children (75%) with gastric symptoms had detectable circulating antibody titers. Elevated titers were also found in institutionalized children and in adults with renal failure.

Adolescent↗
PubMed1993

Diagnosis of HIV-1 infection by PCR with two primer pairs.

We have used two different primer pairs to assess HIV-1 infection of peripheral blood mononuclear cells (PBMC) by polymerase chain reaction (PCR). The study was carried out on 150 individuals: 50 seronegative individuals without risk behaviours for HIV-1 infection, 50 individuals with risk-behaviours but seronegative for HIV-1 and 50 patients with risk-behaviours who were HIV-1 seropositive. Discordances were found between the two primer pairs (SK38/39; SK68/69) in 3 cases. In the non-risk seronegative group, one specimen was scored positive with only one primer pair (SK38/SK39); all the samples belonging to seropositive individuals were found to be positive for HIV-1 DNA using both primer pairs; in the seronegative at risk group 2 samples were positive with only one primer pair (SK38/SK39), and 4 samples were found positive by both primer pairs (SK38/39 & SK68/69). Our study demonstrates that discrepant results take place with relatively high frequency; we propose that all specimens should be tested twice using at least two different primer pairs.

DNA Primers↗
PubMed1993

Serum hepatitis B virus DNA detection with S- and C-region-directed probes.

Developments in molecular biology have offered a wide range of nucleic acid probes to detect the genome of hepatitis B virus (HBV). We have tested the ability of two enzyme-linked (alkaline phosphatase) probes to detect HBV-DNA. These hybridise with the S and C regions of the genome of HBV and are used to determine the clinical significance of detecting the two regions. A total of 66 serum samples from patients at different stages of HBV infection was examined. HBV-DNA was detected with at least one of the probes in 17 (85%) patients with HBeAg-positive chronic hepatitis, five (26.3%) with anti-HBe-positive chronic hepatitis and six (66.6%) with acute hepatitis. Although both probes were able to detect as little as 10 pg/ml (2.86 x 10(6) g.E./ml) of a full length HBV-DNA standard, the C-region-directed probe did not react in one patient with acute hepatitis, two with HBeAg-positive and three with anti-HBe-positive chronic hepatitis. When C-region-directed probes are used for diagnostic purposes, results should always be accompanied by hybridisation with probes directed against other regions showing less variability (e.g. S region).

Acute Disease↗
PubMed1993

[Evaluation of DNA-HIV detection in various population groups].

BACKGROUND: To evaluate the diagnostic use of Polymerase Chain Reaction (PCR) for the detection of HIV-DNA. METHODS: We have investigated HIV-DNA in peripheral blood mononuclear cells of 150 individuals: 50 seronegative without recognized factors to acquire HIV infection, 50 seronegative that showed risk habits and 50 seropositive. For amplification we have used primers SK38/SK39 which amplify a conserved region of 114 bp from HIV's gag gen. The detection of the amplificate was performed using solution hybridization with 32P-labelled SK 19, 6% polyacrylamide gel electrophoresis and autoradiography. RESULTS: We have detected HIV-DNA at every seropositive patient (100%), 6 samples from seronegative individuals that showed risk habits and 1 sample from non-risk seronegative individuals. CONCLUSIONS: Polymerase chain reaction represents a diagnostic tool at HIV infection, specially for those patients where seroconversion can not be demonstrated by conventional methods.

DNA, Viral↗
PubMed1992

An enzyme-linked (alkaline phosphatase) oligonucleotide probe for the detection of serum hepatitis B virus DNA.

Serum HBV-DNA detection represents a new and important diagnostic tool for the hepatologist, as well as a prognostic and therapeutic guide. Though most laboratories use genomic radioactive probes, the appearance of commercially available enzyme-linked oligonucleotide probes, which simplify the method, represents an advance in HBV-DNA detection. In order to verify the value of an enzyme-linked (alkaline phosphatase) oligonucleotide probe in HBV-DNA detection, we have first compared the results of the detection of serum HBV-DNA in 46 patients at different serological stages of HBV infection using this probe and with those obtained using a genomic P32-labeled probe. Fisher's test analysis of the results shows statistical significance; this indicates a high correlation between methods. Secondly, we have tested 296 sera of patients at different serological stages of HBV infection with the enzyme-linked probe; we have found HBV-DNA in 8 patients with acute hepatitis (61.54%), 61 HBeAg (70.12%), and 7 anti-HBe (12.07%) chronic hepatitis. These results show the value of this probe for routine survey of serum HBV-DNA using a simple method which avoids the use of radioactivity.

Alkaline Phosphatase↗
PubMed1992

[Annual cost of microbial immunological tests for HIV-positive individuals in a hospital center].

The goal of this study is to increase the knowledge of the AIDS cost in a hospital. We have studied the HIV patients diagnosed during a year in our hospital and the charges of the serological tests performed to them. 20.8% of the tests were to study antibodies against HIV (only 20% were positive). After patient distribution between extra or intrahospital origin, we highlight that 61% of the charges are attributed to patients who do not belong to the hospital but to its catchment area. We emphasize the problem that AIDS patients are creating to hospital, being necessary that personal select only useful tests honestly.

AIDS Serodiagnosis↗