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Biomedical subjects

B Lambert

Publications and source records attributed to B Lambert.

At least 181 records · Page 10Linked to original sources
PubMed1982

DNA repair synthesis in subpopulations of human lymphocytes.

Human peripheral blood lymphocytes enriched in T or B cells were exposed to ultraviolet irradiation, nitrogen mustard or methylmethane sulphonate and investigated regarding their capacity for DNA repair synthesis. The DNA repair synthesis, measured as [3H] thymidine incorporated, was determined by autoradiography as unscheduled DNA synthesis (UDS). No systematic difference could be found in the capacity for UDS between the T- and B-cell-enriched fractions. A larger individual variation in UDS was found in the B-cell- compared to the T-cell-enriched lymphocytes.

B-Lymphocytes↗
PubMed1982

Smoking and sister chromatid exchange.

Smokers were shown to have significantly higher SCE levels in peripheral lymphocytes than non-smokers. The increase of SCE was found to depend on the cigarette consumption, and to be significantly higher in subjects with a long than with a short history of smoking. Analysis of the frequency distribution of individual SCE levels and of SCE numbers in single cells gave no indication of subgroups of individuals of subpopulations of lymphocytes with an increased SCE response to smoking. Cells from smokers cultivated in plasma from non-smokers retained a high SCE level, and cells from non-smokers cultivated in plasma from smokers no increase of SCE, indicating that the increase of SCE caused by smoking is due to some type of (long-lived) cellular damage rather than to serum factors. The plasma levels of the primary nicotine metabolite cotinine were found to be increased in heavy smokers as compared to light smokers, and showed an excellent correlation with the cotinine levels in the amniotic fluid in pregnant female smokers. No correlation was found between the individual SCE and cotinine levels in smokers, which indicates that the degree of exposure to SCE-inducing genotoxic agents in the cigarette smoke is not related to plasma cotinine levels in any simple way. The induction of DNA strand breaks and SCE by two intermediary benzo(a)pyrene (BP) metabolites was studied in human lymphocytes in vitro. Both 9-OH-BP and BP-7,8-dihydrodiol were found to induce DNA breaks, but only the latter compound induced SCE. The SCE-inducing effect of BP-7,8-dihydrodiol was observed at a very low concentration (0.01 microM), which indicates a possible role for this BP derivative in the smoking-induced increase of SCE in vivo.

Benzopyrenes↗
PubMed1981

Relation between sister chromatid exchange, cell proliferation and proportion of B and T cells in human lymphocyte cultures.

Human B and T lymphocytes differ in the rate of cell proliferation and frequency of sister chromatid exchange (SCE) when cultured separately in short-term cultures. This difference could theoretically be responsible for part of the variation in the SCE-frequency previously observed among healthy subjects since there is individual variation in the proportion of B and T cells in the peripheral blood. We have therefore studied cell proliferation and SCE-frequency in conventional short-term cultures of lymphocytes from 28 healthy subjects with different proportions of B and T cells. The percentage of B or T lymphocytes did not correlate with the SCE-frequency, nor with the rate of cell proliferation in culture. However, a significantly higher SCE-frequency was found in slowly proliferating cultures than in cultures with a high rate of turn over. Thus, the rate of cell proliferation appears to be an important determinant of the SCE-frequency in conventional lymphocyte cultures. Although the data do not exclude attribution of the difference in SCE- frequency between rapidly and slowly growing cultures to differences in subpopulations of lymphocytes, it appears less likely that B and T cells constitute these tentative subpopulations.

B-Lymphocytes↗
PubMed1981

Gluconobacters from honey bees.

Fifty-six Gluconobacter strains and one Acetobacter strain were isolated from honey bees and their environment in three different regions in Belgium and identified phenotypically. Polyacrylamide gel electrophoresis of the soluble cell proteins showed that two different types exist within the Gluconobacter isolates: strains from type A were found in samples of the three regions, whereas strains from type B were only isolated in two of the three regions. Both types could occur in bees from the same region, from several hives of one bee keeper and from one hive. Strains from type A were almost identical with collection strain G. oxydans subsp. suboxydans NCIB 9018, whereas strains from type B constituted a new protein electrophoretic type within the genus Gluconobacter. Although Gluconobacter is apparently associated with honey bees, it is not known whether it is important or required for the bees or any hive product.

Animals↗
PubMed1981

Decreased UV-induced DNA repair synthesis in peripheral leukocytes from patients with the nevoid basal cell carcinoma syndrome.

The UV-induced DNA repair synthesis in peripheral leukocytes from 7 patients with the nevoid basal cell carcinoma syndrome was compared to that in peripheral leukocytes from 5 patients with basal cell carcinomas and 39 healthy subjects. A dose response curve was established for each individual, and maximum DNA repair synthesis was used as a measure of the capacity for DNA repair. The patients with the nevoid basal cell carcinoma syndrome had about 25% lower level of maximum DNA repair synthesis as compared to the patients with basal cell carcinomas and control individuals. The possibility that DNA repair mechanisms may be involved in the etiology to the nevoid basal cell carcinoma syndrome is discussed.

Adult↗
PubMed1981

Genetic aspects of psoriasis: mode of inheritance and action of PUVA on DNA.

The results of some family and experimental studies related to psoriasis are summarized. Complex segregation analysis of Lomholt's classical family material of psoriasis from the Faroe Islands gave clear evidence of a major locus (additive gene with a frequency of 0.07) plus a strong polygenic component (genetic heritability 0.87). An analysis of another family material showed complete linkage between the major locus for psoriasis and the HLA region. Treatment of cells with 8-methoxypsoralene plus a small dose of UVA induces monoadducts, some of which appear to remain in the DNA for at least 7 days of post-treatment incubation. These monoadducts can be activated to form DNA cross-links by a second, larger UVA dose. 8-Methoxypsoralene plus UVA-induced DNA cross-links can be modified by a repair process which involves the formation of DNA breaks. This process in not observed in XPA cells.

DNA↗
PubMed1980

Synergic effect of insulin and prostaglandin E1 on stimulated lipolysis.

1. The inhibitory effect of prostaglandin E1 on free fatty acid release from adipose tissue is significantly greater when the lipolysis is stimulated by 1-methyl-3-isobutyl xanthine than when stimulated by adrenaline. 2. The antilipolytic effect of insulin on adrenaline and 1-methyl-3-isobutyl xanthine stimulated lipolysis, is suppressed in the presence of inhibitors of prostaglandin synthetase i.e. indomethacin or phenelzine. 3. In the presence of phenelzine, the lack of effect of insulin on adrenaline and 1-methyl-3-isobutyl xanthine lipolysis is overcome by a small amount of prostaglandin E1 (10(-10)M) but not of prostaglandin F2 alpha. 4. The addition of prostaglandin E1 (10(-10)M) restores the inhibitory effect of insulin on cyclic AMP accumulation.

1-Methyl-3-isobutylxanthine↗
PubMed1980

Normal UV-induced DNA repair synthesis in peripheral leukocytes from patients with malignant melanoma of the skin.

Seventeen patients with malignant melanoma were compared to 24 control subjects regarding UV-induced DNA repair synthesis. Peripheral leukocytes were irradiated with different UV-doses and the DNA-repair synthesis was measured in presence of hydroxyurea. A dose response curve was established for each individual. No statistical differences were observed when melanoma patients were compared to the controls.

Aged↗
PubMed1980

An etiologic survey of clinical factors in cervical intraepithelial neoplasia: a transverse retrospective study.

In this retrospective survey 235 patients were studied: 123 patients with cervical intraepithelial neoplasia (CIN) and 112 controls. Fourteen epidemiologic variables were reviewed. The stepwise logistic multiple regression analysis demonstrated that age at first sexual contact was the variable most related to CIN appearance, followed by the occupation of the husband. School attendance and socioeconomic indices of the patients' fathers, husbands or partners were lower in the CIN group, as shown in the descriptive analysis. Age at first pregnancy was also found to be lower among CIN patients. Promiscuity and contraception did not seem to play a significant role in the incidence of neoplastic disease. A carcinogenic model is proposed.

Adult↗
PubMed1979

Sister chromatid exchange in peripheral lymphocytes of subjects vaccinated against measles.

The SCE frequency was studied in cultures of peripheral lymphocytes from three subjects before and after vaccination against measles. The immunological vaccination reactions were monitored by antibody titration and by measurement of DNA synthesis in peripheral lymphocytes. In two of the subjects, on the 14th day after vaccination, there was a marked decrease of the SCE frequency coinciding with common clinical vaccination reactions and an increase of DNA synthesis in the peripheral lymphocytes. The increase of antibody titers started on the 17th day. One month later, when the immunological reactions had subsided, the SCE frequency was increased by 25% over the prevaccination level. Third subject displayed a delayed vaccination response due to a simultaneous influenza infection. This subject showed a 50% increase in the SCE frequency on the 14th day as well as 6 weeks after vaccination. These results suggest that significant changes in the SCE frequency may be related to immunological vaccination reactions.

Adult↗
PubMed1979

Absence of genotoxic effects of metronidazole and two of its urinary metabolites on human lymphocytes in vitro.

The antiprotozoan agent metronidazole (1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole) and two of its major human urinary excretion products, 2-methyl-5-nitromidazole-1-yl acetic acid and 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole were tested for genotoxic activity in human lymphocytes in vitro by analysis of chromosome aberrations, sister-chromatid exchanges and DNA-repair synthesis. The positive control compounds methyl methanesulphonate (MMS) and nitrogen mustard (HN2) showed significant genotoxic activity in these tests. No such activity of metronidazole and its two metabolites was detected in concentrations up to 1000 microgram/ml (5.8 X 10(-3) M). Nor did these 3 compounds influence DNA-repair synthesis induced by MMS and HN2. These results suggest that metronidazole, 2-methyl-5-nitroimidazole-1-yl acetic acid and 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole have no direct genotoxic effect on human lymphocytes in vitro.

Chromatids↗