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Biomedical subjects

C Doré

Publications and source records attributed to C Doré.

At least 55 records · Page 3Linked to original sources
PubMed1984

Plasma concentrations of free 5 alpha-androstane-3 alpha, 17 beta-diol and related gonadal steroids during spontaneous and induced sexual maturation in the female rat.

Plasma concentrations of free 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol), 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol), 5 alpha-dihydrotestosterone (DHT) and of testosterone (T) were determined in female rats undergoing spontaneous sexual maturation or pregnant mare's serum gonadotropin (PMSG)-induced precocious ovulation. In the prepubertal period, 3 alpha-diol levels showed an inverse relationship with uterine weights and a significant drop between Days 21 and 26 of life. Postpubertally, 3 alpha-diol concentrations tended to rise again, to a lesser degree, in parallel with increments in plasma T. Concentrations of 3 alpha-diol were increased tenfold 48 h after the administration of PMSG, i.e., at a time when T and estradiol-17 beta also peaked. Concentrations of 3 beta-diol and DHT remained low throughout both experiments. In earlier studies, it was found that exogenous 3 alpha-diol suppresses reproductive function in the immature rat, but the high concentrations of endogenous 3 alpha-diol reported here for the PMSG model clearly do not interfere with ovulation. The observed constellations of plasma steroids are compatible with the postulate of a peripubertal shift in ovarian progesterone metabolism from 5 alpha-reduced C21 steroids to delta 4-3-ketosteroids.

Androstane-3,17-diol↗
PubMed1984

Retinyl acetate-mediated augmentation of resistance to a transplantable 3-methylcholanthrene-induced fibrosarcoma. The dose response and time course.

An otherwise conventional diet supplemented with retinyl acetate (vitamin A acetate; VAA) increased a specific antitumor resistance in vivo in mice, and this appeared to be due to the enhancement of immune functions rather than a direct antitumor activity. A range of VAA doses (up to 0.8 g VAA per kg of diet), fed for more than 6 months, did not induce any obvious signs or symptoms of hypervitaminosis A. The augmentation of resistance to transplanted tumor was linearly dependent on the dose of VAA. There was also a positive linear relationship between the resistance to transplanted tumor and the length of exposure to supplementary VAA relative to tumor inoculation time. The maximum resistance to transplanted tumor was observed in VAA-fed mice when the enrichment of the diet with VAA started three or more weeks before inoculation of tumor, whereas initiation of the VAA diet on the day of tumor administration or later had a negligible effect on the growth of tumor.

Animals↗
PubMed1983

Enhancement of specific antitumor immunity in mice fed a diet enriched in vitamin A acetate.

Age-matched male CBA mice on a conventional or a vitamin A acetate (VAOAc)-rich diet were immunized with irradiated cloned 3-methylcholanthrene- or Harvey sarcoma virus-induced (McSa-1 or HT3-2.1) sarcoma cells and then challenged with viable corresponding or unrelated (non-crossreacting) syngeneic sarcoma cells. The survival of the specifically immunized mice on the VAOAc diet was significantly prolonged in comparison with all control groups of mice as assessed by using logrank tests. Moreover, the specific immunization markedly decreased the incidence of tumors after the McSa-1 (but not HT3-2.1) challenge in a group of mice on the VAOAc diet (5% tumor incidence) compared with the equivalent group on the control diet (50% tumor incidence). Neither the VAOAc diet nor in vivo immunization alone or combined influenced natural killer cell activity. Specific T-cell-mediated cytotoxicity after in vivo priming and in vitro boosting with sarcoma cells was increased in VAOAc-fed mice. However, the marginal increase in cytotoxicity does not in itself explain the strikingly increased resistance to tumor transplants in preimmunized mice on the VAOAc diet in comparison with preimmunized mice on the control diet. The results indicate that a diet enriched in VAOAc can modify the ability of the immune system of a mouse to respond effectively to tumor antigens and can influence whether a tumor grows or regresses.

Animals↗
PubMed1982

Sperm size in patients with inflammatory bowel disease on sulfasalazine therapy.

The size of the heads of spermatozoa from eight men with chronic inflammatory bowel disease (IBD) treated with sulfasalazine (SS) were measured by image analysis. These were compared with the size of sperm heads from noncolitic men with normal semen indices and with the sperm head size of noncolitic oligospermic men. The patients on SS therapy had a significantly larger sperm head size for the 99th percentile than the noncolitic oligospermic men. After withdrawal of the drug, sperm head size increased further before becoming smaller. The size did not return to that of the sperm of men with normal semen indices during the period studied. Possible mechanisms for the increase in sperm size are discussed and its association with the reversible infertility caused by SS medication.

Adult↗
PubMed1982

Chronic exposure of rats to enflurane 200 p.p.m.: no evidence of toxicity or teratogenicity.

Adult male or female rats were exposed either to enflurane 200 p.p.m. or to air for up to 63 days before mating and subsequently throughout the pregnancy of the females. The treated animals were exposed for 8 h per day, 5 days per week for a maximum total of 100 days. The parents and progeny-were studied. Additional positive controls with vitamin A palmitate demonstrated that the strain of animals was susceptible to a known teratogen. No abortifacient effect was observed with these conditions of exposure to enflurane. Skeletal examination of the fetuses failed to reveal any major teratogenic effect. The parents remained healthy clinically, whilst autopsy and histopathological examination failed to reveal any consistent organ injuries which could be blamed on exposure to enflurane. In rats at least, environmental pollution with enflurane appears not to be associated with significant toxicity or teratogenicity.

Abnormalities, Drug-Induced↗
PubMed1982

Prediction of energy requirements of obese patients after massive weight loss.

A regression analysis was made of resting metabolic rate on weight and body composition in 140 women with varying degrees of obesity. In 19 severely obese women before weight loss, average resting metabolic rate was 290 ml O2/min, or 4 per cent higher than predicted from the regression equation. After losing 30 kg in one year the average metabolic rate of this group was 234 ml O2/min, 1 per cent higher than that predicted for their reduced weight. Women whose metabolic rate was high or low relative to prediction before weight loss tended to maintain this status after weight loss (P less than 0.05). There is a close relation between resting metabolic rate and total energy expenditure. We conclude that there is a reduction in energy requirements for weight maintenance after massive weight loss, but the requirements of obese patients after weight loss are similar to those of people of comparable weight who have not reduced.

Adolescent↗
PubMed1981

Urban hypothermia: preferred temperature and thermal perception in old age.

A study of 17 elderly men and 13 young adults of similar body build and wearing equivalent clothing insulation (0.8 clo) showed that when given control over their environment the elderly preferred the same mean comfort temperature (22-23 degrees C) but manipulated ambient temperature much less precisely than the young. Slow adjustment of ambient temperature was related to some cases to a higher temperature-discrimination threshold. These findings suggest that both physiological and behavioural changes contribute to the increased vulnerability of old people in cold conditions.

Adolescent↗
PubMed1981

Maternal and paternal chronic exposure to enflurane and halothane: fetal and histological changes in the rat.

Adult male and female rats were exposed chronically to halothane 10 p.p.m., enflurane 20 p.p.m. or air for up to 64 days before mating and subsequently throughout the pregnancy of the females. The parents, progeny and, in a few cases, the subsequent generation, were studied. No abortifacient effect was seen with either agent. The groups exposed to anaesthetic had larger litters with lighter fetuses compared with their control groups. Skeletal examination did not reveal any major teratological effects for either agent. No consistent organ injury could be associated with chronic exposure to the agents under the conditions of this study.

Abnormalities, Drug-Induced↗
PubMed1981

An assessment of anti-schistosomal treatment on physical work capacity.

Acting as their own controls, village subjects from the Gezira are of the Sudan with relatively high levels of schistosomiasis infection were first tested in an exercise laboratory in Khartoum and the tests were then repeated after a period of about 1 yr during which time the subjects were treated with hycanthone and periodically monitored to ensure that they had remained free of the disease. In the meantime they were also given anti-malarial prophylaxis. Laboratory tests showed a significant improvement in physiological work capacity of up to 20% after treatment compared with untreated controls. An overall improvement in pulmonary function, particularly forced vital capacity, was observed as well as a significant increase in mean haemoglobin concentration by 1.1 g/100 ml of blood in the treated group. Apart from these improvements in physical working capacity, the treated subjects subjectively felt better after the exercise tests, as expressed by the disappearance of fatiguability.

Adolescent↗
PubMed1976

Sweat responses in the aged.

The sweating responses to thermal stimulation and to the intradermal injection of acetyl choline or methacholine were measured in 28 men and 18 women aged 70 and over and were compared with the responses in young control subjects of both sexes. There was found to be a marked reduction in the sweating activity of the majority of aged men in comparison with the younger age groups and the body temperature threshold for the onset of sweating was increased. The reduced response and elevated threshold were even more pronounced in aged females. There is considerable variability in response in different subjects and at different bodily sites. Impairment of thermoregulatory function due to diminished or absent sweating is thought to be one of the factors responsible for increased mortality in the elderly population during heat-waves.

Acetylcholine↗
PubMed1976

Factor analysis of analogue scales measuring subjective feelings before and after sleep.

A series of 18 visual analogue scales was used to report the subjective feelings of 38 healthy subjects on 732 occasions during experiments concerned with the quality of sleep. Factor analysis of scores from these scales, both for all subjects combined and within each of four subjects separately, yielded two factors consistently -- 'alertness' and 'tranquillity'. Scores derived from the first factor indicated that, in the laboratory setting levels of immediately after waking in the morning were reduced, in relation to those before falling asleep on the previous night.

Adolescent↗
PubMed1976

Energy expenditure and physiological performance of Sudanese cane cutters.

The thermal and exercise tolerances of 165 Sudanese cane cutters were measured in the laboratory and related to work performance and productivity in the cane fields. The results showed that the amount of cane cut per minute in the field was significantly correlated with changes in body weight (r = +0-53) during the third hour of work, aerobic energy expenditure (r = + 0-43), and cardiac frequency during work. These variables in turn were associated with predicted maximal power output (VO2 max) measured in the laboratory. The average energy expenditure during cane cutting was 1-66 +/- 0-33 1/min-1 (34-9 kJ/min-1) which represents approximately 60% of the workers predicted VO2 max. This rate of energy expenditure was sustained in the cane fields for at least three hours without significant pauses for rest. The sweat losses measured in 32 cane cutters during the two and three hours of work averaged 637 +/- 221 and 770 +/- 282 g/h-1 respectively, while the mean urine temperature immediately on cessation of effort was 37-74 +/- 0-46 degrees C. Despite the additional environmental heat load of the tropics, it would seem that cane cutters performing a self-paced task demanding heavy physical effort, are able to sustain work levels well in excess of those recommended for most European factory workers without obvious signs of fatigue or heat stress.

Adult↗
PubMed1976

Physiological performance and work capacity of Sudanese cane cutters with Schistosoma mansoni infection.

Physiological tests of work performance and measurement of field productivity were made in 194 Sudanese cane cutters in order to study the effect of Schistosoma mansoni infection. The cane cutters were selected from two age ranges (16-24 and 25-45 years) and subdivided into three clinical groups: not infected, infected with, and infected without clinical signs of hepatosplenomegaly. Men infected with Schistosoma haemotobium, malaria (blood film), or with hemoglobin levels less than 10 g/100 ml were excluded. There was a statistically significant (P less than 0.002) higher mean hemoglobin concentration in those not infected but the mean difference was less than 1 g/100 ml. Submaximal responses to exercise on a stationary bicycle ergometer, oxygen intake, ventilation, tidal volume, cardiac frequency and estimated maximal aerobic power output calculated both in absolute terms and relative to lean body mass and leg volume were similar in the six groups of cane cutters. No significant differences were found in physique, body composition or in thermoregulatory function tests. The cane cutters were found to have little natural acclimatization to heat in terms of sweating capacity when compared with a group of fully acclimatized Sudanese soldiers. The mean productivity (mean daily weight of cane cut per man) was significantly correlated with the individual's estimated maximum aerobic capacity determined in the laboratory, but not with the degree of S. mansoni infection. The noninfected group was less "efficient" (mean productivity:oxygen intake) during cutting than the infected groups but a larger proportion of the noninfected were in their first season of cutting. There was a positive correlation between the number of seasons' cutting experience and the individual's age, degree of infection and mean productivity. Cane cutters studied in this investigation were a relatively fit, active population from whom the more seriously ill were excluded. These results do not, therefore necessarily reflect the effects of S. mansoni on physiological work capacity and productivity of more static populations in areas of high endemicity.

Adolescent↗