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Biomedical subjects

B S Thomas

Publications and source records attributed to B S Thomas.

At least 19 recordsLinked to original sources
PubMed1997

Direct and indirect effects of selected risk factors in producing adverse consequences of drug use.

A path analysis was performed to examine the usefulness of multiple pathway risk factors in explaining and predicting youthful alcohol, tobacco, and other drug (ATOD) misuse and its adverse consequences. The risk factors alienation, trait anger, interaction anxiety, and cognitive motivation for drinking were used as exogenous variables with earliness of onset, ATOD use, and adverse consequences of ATOD use serving as endogenous variables. Firm support emerged for both direct and indirect effects of the risk factors on both use and adverse consequences of use.

Achievement↗
PubMed1996

A path analysis of gender differences in adolescent onset of alcohol, tobacco and other drug use (ATOD), reported ATOD use and adverse consequences of ATOD use.

Gender differences in the ways a risk factor approach explains onset of using alcohol, tobacco and other drugs (ATOD), reported use of ATOD and adverse consequences from ATOD use were investigated by means of separate path analyses for male and female adolescents. A fully recursive model was specified in which alienation, trait anger, interaction anxiety and cognitive motivation for ATOD use comprised the first column variables which were used to predict earliness of onset. For the second step, column one variables plus onset were used to predict ATOD use. In the final step, column one variables plus onset and ATOD use were used to predict adverse consequences of ATOD use. An ex post facto design was used in surveying 796 high school students in a single Midwestern community. The data from this sample supported the predictive validity of the theoretical model. In addition to the expected indirect or mediated effects of the risk factors via onset of ATOD use on ATOD use and via onset and ATOD use on adverse consequences of ATOD use, there were direct effects of column on risk factors on both ATOD use and on adverse consequences of ATOD use for both males and females, lending support to the concept of multiple pathway risk factors. The three gender differences that emerged in the separate path analyses were entirely consistent with the gendered deviance model.

Adolescent↗
PubMed1995

The effectiveness of selected risk factors in mediating gender differences in drinking and it problems.

PURPOSE: The purpose of this study was to investigate gender differences in adolescents' alcohol use, adverse consequences of alcohol and other drug (AOD) use and the effectiveness of selected risk factors in mediating gender differences. METHODS: A cross-sectional survey design was adopted. Data were collected from a sample of high school students (n=919) in one midwestern community. Four criteria for examining potential mediated relationships were addressed. RESULTS: Expected differences in relation to males' higher levels of frequent and heavy drinking, adverse consequences of AOD use and risk factors were found. All risk factors were significantly related to adverse consequences, but alienation was not related to drinking behavior. In a one-way ANOVA, the main effects of gender were significant for both drinking behavior and adverse consequences of AOD use. In a two-way ANOVA, the main effects of a risk factor index reduced the main effects of gender substantially. CONCLUSIONS: Controlling risk factor levels mediates gender differences in the outcomes, drinking behavior and adverse consequences of AOD use.

Adolescent↗
PubMed1993

The role of free fatty acids in regulating the tissue availability and synthesis of sex steroids.

Sex steroids and dietary fat intake have been implicated in the growth of breast tumours. We have previously shown that the plasma free oestradiol fraction is increased in women with breast cancer and that the addition of free fatty acids (FFA) to plasma can increase the free oestradiol fraction in vitro. In the present study we have examined the distribution of oestradiol and testosterone in serum obtained from European women (EW) and Asian (Gujarati) women (GW) living in north-west London. Fat intake by these women is similar but GW, who are vegetarians, consume a greater proportion of unsaturated fats. In serum from perimenopausal GW, the free testosterone concentration was significantly higher than for EW (11.1 +/- 3.6 pmol/l vs 8.7 +/- 3.4 pmol/l, p < 0.05). Although a significant correlation was found between the free testosterone and FFA concentrations for GW (r = 0.49, p < 0.05), concentrations of sex-hormone binding globulin (SHBG) were significantly lower in GW than EW. The finding of lower SHBG concentration in GW was confirmed in a second study in postmenopausal women (EW, 60.1 +/- 34.1 nmol/l; GW, 37.8 +/- 20.5 nmol/l, p < 0.05). However, no difference in the free oestradiol fraction or concentration was detected for EW and GW and no correlations with total or individual FFA were found. It is concluded from this study that while dietary fats may have an important role in the development of breast tumours, it is unlikely to be mediated by FFA inhibiting the binding of sex steroids to plasma proteins.

Adult↗
PubMed1993

Drug use in a small midwestern community and relationships to selected characteristics.

A description of 1074 high school students' alcohol and other drug (AOD) use along with the consequences of such use was supplemented with comparisons of grade level and gender differences and analyses of the relationships between AOD use and incidence of adverse consequences with grade point average, attendance at religious services, frequency of dating, frequency of driving a car and frequency of having trouble at school. Alcohol was clearly the drug of choice and produced a variety of adverse consequences. Most frequently reported were arguments, trouble with parents and at school and nausea or vomiting. Grade level differences were found, but few significant gender differences emerged. Significant relationships between AOD use and consequences with all other independent variables were found.

Adolescent↗
PubMed1993

The role of selected risk factors in predicting adolescent drug use and its adverse consequences.

The purpose of this study was to examine the effectiveness of selected risk factors in predicting alcohol and other drug (AOD) use and adverse consequences of use. Three regression analyses were performed on four categories of risk factors: individual, family related, school related, and social related. The sample size was 887 (99%). Significant predictors for AOD use were grade level, participation in religious services, GPA, frequency of dating and driving, trouble at school, mastery, and family management index. Predictors for adverse consequences were GPA, frequency of dating, trouble at school, family management index, risk taking, alienation, susceptibility to peer pressure, and living arrangements.

Adolescent↗
PubMed1992

Patterns of alcohol and other drug use in an Iowa community.

From a baseline survey of high school students in two school systems, information was obtained to describe patterns of alcohol and other drug (AOD) use and adverse consequences of use, compare indices of AOD use and consequences for grade level and gender differences, and examine relationships of indices to selected individual, family-related, and social competence/adjustment-related risk factors. Though use of illicit drugs was reported at low levels, prevalence of drinking and incidence of binge drinking were relatively high. Increases in AOD use and adverse consequences with age and grade level were found, but gender differences were not found. Relationships of AOD use and adverse consequences to selected individual, family, and social risk factors were consistent with a substantial body of prior work but exceptions were found. Strongest correlations to both indices were found for risk taking, sense of mastery, family management/cohesion, peer pressure, and social/school adjustment.

Adolescent↗
PubMed1992

The affective outcomes of course work on computer technology in nursing.

At the University of Iowa, nursing students are introduced to computer technology as one unit in a course designed to explore nursing as a profession. A single group, pretest/posttest design was used to evaluate changes in attitudes associated with the course work. Relationships of attitudes scores and eight background variables were studied. Posttest attitudes scores were significantly higher than pretest scores. The attitudes scores were positively related to skills scores at a statistically significant level of .05, with no significant relationship between attitudes scores and knowledge base scores. Four of the eight background factors were related to the attitudes scores at a statistically significant level of .05.

Adult↗
PubMed1991

Cigarette smoking and steroid hormones in women.

Epidemiological evidence has suggested that cigarette smoking has an anti-oestrogenic effect in women, but the effects of smoking on steroid hormone metabolism are not fully understood. We compared serum concentrations of oestradiol, progesterone (luteal phase) and dehydroepiandrosterone sulphate (DHEA-S), and urinary excretion rates of six steroids of predominantly adrenal origin, in healthy premenopausal and postmenopausal female smokers and non-smokers. Serum concentrations of oestradiol, progesterone and DHEA-S did not differ between smokers and non-smokers by greater than 5%, and none of these differences was statistically significant. Mean urinary excretion rates of androsterone, aetiocholanolone, DHEA, 11-keto-aetiocholanolone, 11-hydroxyandrosterone and 11-hydroxyaetiocholanolone were very similar in smokers and non-smokers in premenopausal women, but were from 2-44% higher in smokers than non-smokers in postmenopausal women. The difference was statistically significant only for 11-hydroxyandrosterone. These results confirm previous reports that cigarette smoking does not affect serum oestradiol in premenopausal or postmenopausal women, but provide only weak evidence to support previous findings of increased levels of some adrenal steroids in postmenopausal women smokers. The mechanism for the apparent anti-oestrogenic effect of cigarette smoking remains unclear.

Adult↗
PubMed1990

Erythrocyte membrane stearic acid: oleic acid ratios in colorectal cancer using tube capillary column gas liquid chromatography.

Erythrocyte fatty acids were measured in 32 patients with colorectal cancer (four with recurrent disease), four patients with large colorectal adenomas, and 42 hospitalised patients without cancer. No significant differences were found with respect to any of the fatty acids between these groups. In particular there was no difference between the erythrocyte stearic acid: oleic acid ratios (mean +/- SD) between the cancer cases (1.07 +/- 0.31) and the control cases (1.09 +/- 0.31, 2-tailed Mann-Whitney U test). No difference in this ratio was observed with respect to age or sex and in the case of colorectal cancer, to the Dukes' stage, degree of tumour differentiation, or recurrence. A significant correlation was found between stearic acid concentrations in plasma and erythrocytes from fasting individuals (r = 0.477, n = 24, P less than 0.05). This study provides further evidence that the erythrocyte stearic acid: oleic acid ratio is of no value for diagnosing primary or recurrent colorectal cancer.

Aged↗
PubMed1989

Hormones are ambiguous risk factors for breast cancer.

Women with breast cancer whose blood and urinary androgens are at the lower end of the normal range have an early age at diagnosis, a rapid recurrence rate after mastectomy and tumours that are unresponsive to endocrine therapy. The most plausible explanation for these results is that the androgens are not involved in tumour initiation but control tumour growth rates after the malignant transformation has occurred. If this is so, endocrine case/control studies in which growth rates are not measured are an inefficient way of studying the endocrinology of breast cancer. It is suggested that the oestrogens and androgens should be considered as a single functional unit in future research.

Adult↗
PubMed1988

Erythrocyte membrane stearic and oleic acid ratios in breast cancer.

A case control study has been conducted to determine the value of stearic/oleic acid ratios in the erythrocyte membranes of women at the time of presentation with breast cancer. No difference was found between the stearic/oleic acid ratio of cases and that of controls with benign breast condition or normal volunteers. Furthermore, within clinical stages of breast cancer, no differences were detected. This ratio does not appear to be of value as a marker of malignancy, or of tumour burden.

Breast Neoplasms↗
PubMed1988

Urinary epidermal growth factor excretion and breast cancer risk.

The amount of urinary epidermal growth factor (EGF) excreted was determined in 350 normal women of whom 37 subsequently developed breast cancer. These were a group of women selected on a case-control basis from 5000 volunteers who had participated in a prospective epidemiological study. Urinary EGF excretion was not correlated with known risk factors such as age at menarche or menopause, age at first or last full-term child or parity. Neither was it associated with day or length of menstrual cycle, breast mammographic parenchymal pattern or the blood concentration of prolactin, dehydroepiandrosterone or its sulphate ester. Univariate analysis indicated that the amount of urinary EGF was significantly correlated with urinary creatinine (P less than 0.001), age (P less than 0.001), urinary androsterone (P less than 0.02) or aetiocholanolone (P less than 0.02), height (P less than 0.05) and weight (P less than 0.05). However, multivariate analysis showed that the amount of urinary EGF was correlated only with creatinine excretion (P less than 0.001) and age (P less than 0.001) and that the significance of the other correlations were probably due to the confounding influence of creatinine.

Adult↗
PubMed1988

An autoimmune aetiology for hypothyroidism following interferon therapy for breast cancer.

Alpha-interferon has been administered as an adjuvant treatment for women with loco-regional relapse of breast cancer. During the course of treatment 5/10 (50%) of women receiving interferon developed de novo thyroid autoantibodies. Three patients became clinically myxoedematous, with biochemical evidence of hypothyroidism which responded to thyroxine replacement therapy. The leucocyte alpha-interferon preparations used in the trial enhanced Class I but not Class II MHC antigens on thyrocytes in vitro. These data strongly suggest that patients receiving alpha-interferon therapy should be closely monitored for the possible development of thyroid dysfunction and that thyroid antibody determination can greatly help to predict overt thyroid clinical abnormalities.

Autoantibodies↗
PubMed1988

A prospective study of the relationship between serum vitamins A and E and risk of breast cancer.

In an 8 year prospective study (1977-1985) on breast cancer, blood was taken from 5,086 women resident in Guernsey, and the serum stored at -20 degrees C. During this period 30 women developed the disease and their serum samples were analysed for vitamins A and E, and for retinol-binding protein (RBP). A further 288 age-matched control sera (up to 10 per pre-cancer case) were similarly analysed. No relationship was found between any of these substances and subsequent development of breast cancer. A significant correlation between increasing age and vitamin A (r = 0.46, P less than 0.001) and RBP (r = 0.36, P less than 0.001) concentrations was observed. There was also a trend for increased blood concentrations of vitamin E with age, but this was not significant. Serum RBP and vitamin A concentrations were highly correlated (r = 0.91, P less than 0.0001).

Adult↗
PubMed1988

Sex hormone-binding globulin and the natural history of breast cancer.

Low concentrations of SHBG in the blood appear to be related to rapid tumour growth rates whereas normal values are associated with slower rates. The inferences drawn from these and other experimental results are as follows: 1. It is no longer necessary to postulate that an abnormal endocrine environment is related to the risk of breast cancer. 2. Variation within the normal range of endocrine function may be sufficient to account for marked differences in the growth rates of transformed cells. 3. It is suggested that women whose tumours arise in an environment characterised by SHBG concentrations at the lower end of the normal range (and, hence, non-SHBG-bound oestradiol levels at the top end of the range) will tend to have an earlier age at diagnosis, a lower frequency of oestrogen-receptor positive tumours and a lower proportion of hormone responsive tumours than women with SHBG levels at the top of the range. 4. Case/control studies in which growth rates are not taken into account may be difficult to interpret.

Adult↗