Search PubMed⌕ Search

Biomedical subjects

J Kaldor

Publications and source records attributed to J Kaldor.

132 records · Page 8Linked to original sources
PubMedDate not supplied

Induction of specific base-pair substitutions in E. coli trpA mutants by chloroethylene oxide, a carcinogenic vinyl chloride metabolite.

Chloroethylene oxide (CEO), an ultimate carcinogenic metabolite of vinyl chloride, induces base-pair substitution mutations but not frameshift mutations in bacteria. The mutational specificity of CEO was investigated in Escherichia coli, using the trpA mutants developed by Yanofsky. Reversion frequencies to tryptophan prototrophy were analysed, and CEO was found to induce more GC----AT transitions than AT----TA transversions, in addition to a low frequency of other types of substitution. This specificity indicates that CEO is mutagenic through a miscoding DNA adduct. The results are discussed in relation to the various CEO-DNA adducts formed and to their reported or expected mispairing properties.

Alleles↗
PubMedDate not supplied

Statistical analysis of Salmonella test data and comparison to results of animal cancer tests.

A quantitative framework for the analysis of results of the Salmonella (Ames) test is presented, and the relationship between mutagenesis and carcinogenesis is examined. Color graphics are used for the Salmonella data to describe variability, and trends across multiple chemicals and test conditions. Positivity in the Salmonella test, using statistical criteria to classify results, is compared to positivity in carcinogenesis bioassays for 48 chemicals tested in NCI/NTP-sponsored programs. Sensitivity of the Salmonella test across 5 tester strains was 91% (21/23), while specificity was only 36% (9/25). Results were most concordant for TA100 Aroclor-induced rat S9: sensitivity was 87%, specificity 64%. The correlation of mutagenic potency and carcinogenic potency was 0.41 (p less than 0.001) for 80 chemicals, using results from both the general published literature and the NCI/NTP-sponsored programs. After removal of 3 extreme values, the correlation was 0.24 (p = 0.04).

Animals↗
PubMedDate not supplied

Immunoblot confirmation of immune response to Campylobacter pyloridis in patients with duodenal ulcers.

The specificity of serum immune responses to Campylobacter pyloridis that were found in the sera of patients with duodenal ulcers has been confirmed by means of the Western blot method. The presence of the same immune response to the organism in apparently healthy individuals, especially older people, suggests a repeated exposure throughout life to this organism, the source of which remains unknown.

Adult↗
PubMedDate not supplied

Importance of human papillomavirus endemicity in the incidence of cervical cancer: an extension of the hypothesis on sexual behavior.

The risk of cervical cancer for a woman depends largely on the probability of being infected with some specific types of Human Papillomavirus (HPV). In the control groups of four case-control studies in Colombia and Spain we have shown a strong correlation between the number of sexual partners of males and females and HPV DNA prevalence in the genital tract. Our results suggest that the lifetime number of sexual partners in both sexes are surrogates of the probability of HPV infection and, as such, insufficiently explain the geographical variation in the incidence of cervical cancer. It is proposed that the high rates of cervical cancer in Latin America are linked to the largely unknown characteristics of the HPV endemicity in the population and to the absence of widespread screening for cervical neoplasia. Reliable surveys on the HPV prevalences in selected social groups (i.e., young males and prostitutes) as well as in populations in countries at different risk of cervical cancer are required.

Adult↗
PubMedDate not supplied

Serum antibody response to active infection with Cryptococcus neoformans and its varieties in immunocompetent subjects.

Using a class-specific enzyme immunoassay IgG and IgA anticryptococcal antibody was measured in 400 serum specimens at 1 week to 11.7 years after diagnosis from 43 immunocompetent subjects with confirmed active cryptococcosis. The prevalence of IgG was 86% at diagnosis, rose to 100% by 2 weeks and remained high thereafter. IgA prevalence was 71% at diagnosis, rose to 75% at 2 weeks and then fell over 2 years. IgG and IgA prevalence in paediatric controls was 5% and 0%, respectively. Mean antibody levels showed the same pattern and neither levels nor prevalence were influenced by age, sex or site of infection. Patients with the variety gattii infection had a greater antibody response than those with the variety neoformans which was significant for IgA. Specific anticryptococcal antibody was regularly present in conjunction with cryptococcal antigen at diagnosis. IgG persists but IgA falls over 1-2 years. The assay described may be a useful tool to study the antibody response and seroepidemiology of infection with C. neoformans.

Adult↗