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Biomedical subjects

K I Baghurst

Publications and source records attributed to K I Baghurst.

5 recordsLinked to original sources

Diet, prolactin, and breast cancer.

Relationships between dietary nutrients and plasma prolactin concentration were studied in 249 women with a history of nonskin cancers among first-degree female relatives. For each quintile of nutrient density, the odds ratio (OR), relative to the lowest quintile, of having an elevated (above the median) prolactin concentration was estimated by logistic regression, taking into account parity, menopausal status, and current tobacco-smoking habits. For nutrient densities estimated from 24-h recall data there was a significant positive association between plasma prolactin concentration and increasing saturated fatty acid intake; the OR of elevated prolactin in the top quintile was 3.1 [95% confidence interval (CI) 1.2-8.1] and there was a negative association with vitamin C [OR in the top quintile 0.28, (95% CI 0.10-0.78)]. For usual nutrient densities (estimated by quantitative food frequency questionnaire) there was a statistically significant trend (P = 0.04) toward lower prolactin concentrations with increasing sodium density, and a marginally significant positive trend (P = 0.07) with increasing dietary density of refined sugars.

Adult

Public health implications of dietary differences between social status and occupational category groups.

STUDY OBJECTIVE: As there is a social status gradient in chronic disease mortality in Australia, this study aimed to establish whether there were substantial differences among socioeconomically defined groups with respect to food choice and nutrient intake, in the context of risk of nutrition related chronic diseases. DESIGN AND PARTICIPANTS: Cross sectional data were collected from a randomly selected population sample of 1500 urban Australian adults. Data were collected by postal questionnaire, which included an assessment of dietary intake and questions on sociodemographic details. Three measures of social position were collected: occupation, educational status, and income status. Occupation was interpreted both on a continuous, prestige scale, and also as categorical occupational groupings. MAIN RESULTS: The study achieved a 70% response rate. Higher social status was generally associated with healthier dietary intakes, with lower fat and refined sugar densities, and higher fibre densities, but also with higher alcohol density. No differences were found in salt, polyunsaturated fat, protein, or complex carbohydrate densities across groups. Food intake differences were also found between occupational status groups, with the upper social groups tending to consume more wholegrain cereal foods, low fat milk, and fruit, and less refined cereal foods, full cream milk, fried meat, meat products, and discretionary sugar; but also more cheese and meat dishes. CONCLUSIONS: Although this study did show statistically significant differences across social status groups in relation to nutrient and food intakes, these differences were small compared to the disparity between intakes of all groups and the recommended patterns of intake, and did not appear to be great enough to be a major explanatory variable in differences in disease risk across groups.

Adolescent

Foetal thyroidectomy and brain development in the sheep.

Sheep foetuses were surgically thyroidectomized at 50-60 days gestation, when thyroid function begins, and the pregnancy was then allowed to continue until 90, 120 or 150 days (term). At these times the foetuses were removed by caesarean delivery, exsanguinated, weighed and dissected. The central nervous system was divided--cerebral hemispheres, brain stem, cerebellum and spinal cord for subsequent analysis. Comparison was made with sham operations on seven foetuses. Thyroidectomy led to a fall in body weight (24.7%) and brain weight (11.7%) at 120 days and 150 days, 31.1% and 24.5% respectively. The hemispheres showed the greatest change and the cerebellum the least. DNA and protein contents were reduced in the hemispheres and cerebellum at 150 days, while in the brain stem and spinal cord the DNA content was not significantly affected. Protein content was, however, reduced indicating a reduced cell size, but not a reduced cell number as in the other two regions. Somatic changes included reduced wool growth, delayed osseous development in the limbs (X-ray assessment) a reduced heart weight (39.1%) and an increased pituitary weight (48.1%). The thyroidectomized lambs failed to survive for more than a few hours after birth or caesarean delivery at 150 days. The findings indicate significant effects of foetal thyroidectomy on brain development in the sheep late in pregnancy along with other evidence of foetal hypothyroidism.

Animals

Foetal brain development in the sheep.

The pattern of normal foetal brain development has been described for the Merino sheep. Controlled flock matings were used and foetuses removed by hysterotomy at 40, 54, 67, 81, 90, 95, 109, 121 and 150 days of gestation. Lambs at 7 days after birth and adults were also studied. The CNS was dissected, separated and weighed as four segments--cerebral hemispheres, brain stem, cerebellum and spinal cord. Determinations of DNA, RNA, protein, cholesterol and water content were subsequently carried out on each segment. Brain weight increased from 0.264 g (40 days) to 52.74 g at 150 days. The ratio to body weight decreased from 6.7% (40 days) to 1.5% (150 days). DNA increased more rapidly from 40 to 90 days in the cerebral hemispheres and brain stem than in the cerebellum and spinal cord and this increase preceded the main increase in weight. Increases in cholesterol and decreases in water content were also more marked in the cerebral hemispheres and brain stem. Increase in brain weight occurred in two phases, one up to 90 days followed by a more rapid and larger increase after 90 days which continued to birth. These two phases appear to reflect an increase in neuroblast multiplication followed by neuroglial multiplication and myelination respectively. At birth, brain weight had reached 50% of adult size, the cerebral hemispheres 52% of adult size, the cerebellum 40% and spinal cord 40%. The relative maturity of the brain at birth justifies the classification of the sheep as a prenatal brain developer.

Animals