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Biomedical subjects

C B Thomas

Publications and source records attributed to C B Thomas.

At least 91 records · Page 5Linked to original sources
PubMed1981

Neoplasm and traumatic events in childhood.

Previous research has suggested that certain objectively defined traumatic events occurring in childhood and/or adolescence may be linked to the appearance of neoplasm later in life. The present report examines four such events-parental death, parental divorce, sibling death, and having been the youngest child for less than two years-for their frequency of occurrence within four groups of physician subjects classified according to current health status as follows: major cancer, skin cancer, benign tumor, and healthy controls. All data had been collected while the subjects were in medical school within the context of a long-term, prospectively oriented study. Major cancer subjects were also compared with their cancer-free siblings with respect to length of time spent as youngest child. Although there was a slight tendency for the trend of the findings to be in accord with the hypotheses tested, no statistically significant differences among groups could be demonstrated.

Attitude to Death↗
PubMed1981

Aminoimidazole carboxamide ribonucleoside toxicity: a model for study of pyrimidine starvation.

Aminoimidazole carboxamide ribonucleoside (AIC-R), a purine precursor, has biphasic effects on the growth of Chinese hamster fibroblasts. At 200 microM AIC-R cell growth is almost completely arrested, while at 50 and 700 microM AIC-R cell growth is comparable to that observed in the absence of nucleoside. The growth inhibition produced by AIC-R is the consequence of inhibition of the orotate phosphoribosyltransferase-orotidylic decarboxylase (OPRT-ODC) reactions, as evidenced by a 87% reduction in the intracellular concentrations of UTP and CTP, accumulation of orotate in the medium, and restoration of normal growth by inclusion of 100 microM uridine in the medium. Inhibition of pyrimidine nucleotide synthesis at 200 microM AIC-R is associated with an 82% reduction in the intracellular concentration of PP-ribose-P and a 150% increase in the concentration of purine nucleotides. Restoration of cell growth to a normal rate at 700 microM AIC-R--a condition under which PP-ribose-P remains depressed and purine nucleotide concentrations are also depressed (40% of control)--and absence of toxicity at 50 microM AIC-R--a condition under which purine nucleotide concentrations are increased by 150% and PP-ribose-P concentration is normal--suggest that the inhibition of OPRT-ODC observed at 200 microM AIC-R is caused by the combination of the reduction in PP-ribose-P and increase in purine nucleotides. These studies provide a better understanding of the control of the OPRT-ODC reactions in the cell and provide additional insight into the basis of pyrimidine starvation induced by purine nucleosides.

Aminoimidazole Carboxamide↗
PubMed1981

Themes of interaction in medical students' Rorschach responses as predictors of midlife health or disease.

The purpose of this study was to examine variations in individual approaches to human relationships among members of a cohort of healthy medical students as revealed by their Rorschach Tests, and to explore the association between the assessed youthful relationship potential and midlife health or illness. In particular, the relationship potential among future cancer victims was found to differ significantly form that of their fellow students who remained healthy or who developed a cardiovascular disorder, but resembled that of those men who later became mentally ill or committed suicide. These prospective findings appear to fit with several retrospective reports stressing the role of human relationships as a psychological factor in the development of cancer.

Adult↗
PubMed1981

Orthogonal dimensions of individual and group forms of the Rorschach.

Most dimensional analyses of traditional Rorschach scoring categories have either failed to control for differences in total R or have done so by introducing a nonstandard mode of administration. Consequently, the results of such studies may be either distorted or of questionable relevance to more typical situations. The present analyses, which compared both group and individual forms of the Rorschach administered to large samples (over 500 each) of male medical students, controlled for differences in total R by using residualized scores from which the linear effects of R had been partialled. The factor-analytic results are expressed in terms of seven easily interpretable factors (including total R), five of which are similar across forms, and simple formulas for deriving norm-referenced factor scores from the data of individual test administrations are provided.

Journal Article↗
PubMed1981

Detection of Mycoplasma bovis specific IgG in bovine serum by enzyme-linked immunosorbent assay.

The enzyme-linked immunosorbent assay (ELISA) was optimized for detection of Mycoplasma bovis-specific IgG in bovine serum. The test is rapid, reproducible, convenient, and sensitive. With this assay, the serum from naturally infected and immunized calves demonstrated the presence of antibodies early in infection and rapid increase in titers during the infection. Cross-reactivity of bovine serum with mycoplasma antigens of bovine, caprine, avian, and environmental sources was tested with this assay system. Cross-reaction was measurable in all instances, with the strongest reaction measured between M bovis and M agalactiae.

Animals↗
PubMed1980

Precursors of premature disease and death: habits of nervous tension.

Patterns of habits of nervous tension (HNT) recorded by medical students who later developed cancer, coronary occlusion, hypertension, or mental illness, or who committed suicide, were compared with those of students who remained healthy 15 to 30 years later. Data came from the 25-item HNT Questionnaire previously reported. Unpaired t tests and two-group discriminant function analyses were the chief statistical methods used. Compared with those of the healthy group, the overall HNT patterns were significantly different for the cancer, coronary occlusion, mental illness and suicide groups. The overall pattern for the hypertension group did not reach significance. It therefore appears that youthful reactions to stress as self-reported in a checklist of habits of nervous tension reflect individual psychobiological differences that are linked with future health or disease.

Adult↗
PubMed1979

Family attitudes reported in youth as potential predictors of cancer.

In long-term prospective study of a cohort of former medical students, men who later developed cancer reported different family attitudes in youth from those of their healthy classmates. The items checked on a Family Attitude Questionnaire by the future cancer group indicated a lack of closeness to parents compared with the items checked by the healthy group. Family attitudes of the future mental illness/suicide group resembled those of the cancer group, while those of the essential hypertension and coronary heart disease groups were like those of the healthy group. These prospective findings appear to fit with those of retrospective studies concerning early family relationships in cancer patients.

Adult↗
PubMed1979

Individual temperament as a predictor of health or premature disease.

Two studies of temperament as a possible predictor of continuing good health or premature disease are reported. In earlier work to determine youthful precursors of premature disease, a number of separate characteristics distinguishing medical students who remain healthy from those with premature disorders have been identified. Characterization by temperament, an expression of innate biological endowment, provides a more global portrayal of an organism that can an aggregate of separate characteristics alone. Criteria for designating three temperament types, termed Alpha, Beta and Gamma, are presented. In 1948, 45 subjects were assigned to one of these types on the basis of youthful characteristics. The subjects in the three temperament groups had different health outcomes 30 years later, significant at the p less than 0.01 level. Gamma type had the most disorders and deaths, Beta type the fewest. A cross-validation study on 127 subjects had similar results at the p less than 0.05 level. Temperament appears to be a variable of predictive potential of individual stamina, or of vulnerability to premature disease and death.

Adult↗
PubMed1978

Characterization of DNA-protein cross-links formed by treatment of L1210 cells and nuclei with bis(2-chloroethyl)methylamine (nitrogen mustard).

Proteins cross-linked to DNA after nitrogen mustard (HN2) treatment of cells or isolated nuclei were purified in CsCl gradients. The protein-DNA cross-links could be cleaved by incubation in dilute acid and could be stabilized by alkali pretreatment. These results indicate that proteins cross-linked to DNA by HN2 are bound to alkylated purines. Analysis of the DNA-bound proteins on NaDodSO4-polyacrylamide gels showed that primarily large nonhistone proteins are cross-linked to DNA in cells treated with HN2. Very little if any histone is cross-linked to the DNA. Comparison of DNA bound proteins from HN2-treated cells and HN2-treated nuclei showed that in general the same proteins are linked to DNA in both cases, but some qualitative and quantitative differences exist.

Alkylation↗
PubMed1978

DNA cross-linking by in vivo treatment with 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea of sensitive and resistant human colon carcinoma xenograms in nude mice.

The DNA alkaline elution technique provides a sensitive assay for the effects of DNA-damaging drugs in mammalian cells. We have adapted this method to permit measurements of effects on DNA in solid tumors. Human colon carcinoma xenografts in nude mice were treated with a single i.p. injection of 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea, and the effects on the DNA were followed for 19 hr. Drug doses in the pharmacological range produced significant reductions in DNA alkaline elution rates in assays in which X-ray was used to introduce a standard frequency of single-strand breaks. These changes in alkaline elution rate were attribute to the production of both DNA interstrand and DNA-protein cross-links, which were distinguished from each other on the basis of the extent to which the effect on elution could be reversed by proteinase K. Crosslinking increased for about 8 hr after treatment with little change thereafter up to 19 hr. A drug-resistant tumor line exhibited substantially less cross-linking than did a drug-sensitive line at all time points examined.

Alkalies↗