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Biomedical subjects

D A Jenner

Publications and source records attributed to D A Jenner.

12 recordsLinked to original sources
PubMed1992

Relationships between blood pressure and measures of dietary energy intake, physical fitness, and physical activity in Australian children aged 11-12 years.

STUDY OBJECTIVE: The aim was to examine associations between blood pressure and dietary energy intake, physical activity, and physical fitness in Australian children. DESIGN: The study was a survey of year 7 children attending schools in metropolitan Perth. SETTING: Survey schools were located in suburbs representative of the range of socioeconomic strata in metropolitan Perth. PARTICIPANTS: Data were obtained on 1311 out of 2045 eligible children (64%). The sample included 681 boys and 630 girls. Mean age was 12.0 (SD 0.4) years. MEASUREMENTS AND MAIN RESULTS: Triplicate blood pressure measurements were obtained using a Dinamap oscillometric recorder. Dietary energy intakes were computed from two week day 24 h records. Physical activity was assessed using questionnaires. Physical fitness was measured using a shuttle run test. Additional measurements included weight, height, and skinfold thickness at four sites. A previous observation of an inverse relationship between diastolic blood pressure and dietary energy intake in boys was confirmed. There was evidence of an inverse relationship in girls but not in boys between blood pressure and physical activity. There was little evidence of relationships between blood pressure and physical fitness. CONCLUSIONS: Compared with weight and body mass index, dietary energy intake and the chosen measures of physical activity and physical fitness are poor predictors of blood pressure in the population studied.

Blood Pressure↗
PubMed1992

Blood pressure and body composition in children: importance of allowing for cuff size.

A cross-sectional study of blood pressure (BP) was conducted in a sample of 1312 Australian school children aged 11-12 yrs. In line with current recommendations for the measurement of BP, a cuff of appropriate size was chosen for each subject based on his or her arm circumference. Analyses revealed statistically significant independent relationships between measured BP and cuff size. Observed relationships in the sample between measured BP and body composition variables were substantially affected when BP measurements were adjusted to remove the effect of cuff size. Cuff-associated biases in estimates of relationships between BP and body composition variables may still exist even though cuffs are carefully chosen to suit arms of different circumferences. It would appear that this potential problem is largely unrecognised. Some previous studies of relationships between BP and body composition may have been affected.

Anthropometry↗
PubMed1991

Reflotron cholesterol measurements in 1112 Australian children aged 10-12 years.

OBJECTIVE: To study the distribution of blood cholesterol concentration in a sample of Western Australian schoolchildren. DESIGN: The Reflotron dry-chemistry system (Boehringer Mannheim, Germany) was used to measure cholesterol in finger-prick blood samples obtained from Year 6 children aged 10-12 years attending government schools in metropolitan Perth. Recruitment methods ensured that children from different socioeconomic strata were represented. PARTICIPANTS: For the 1239 children enrolled in Year 6 in 30 government schools, parental consent to participate was obtained for 1144; of these cholesterol concentration was measured in 1112. RESULTS: The measurement method proved practicable and was generally well accepted. Cholesterol levels were somewhat lower than those obtained using a laboratory reference method and a bias, relative to national quality assurance standards, was estimated to be -0.32 mmol/L. Mean cholesterol level in boys (4.28 mmol/L, SD 0.69) was not significantly different from that in girls (4.35 mmol/L, SD 0.72). Allowing for measurement bias, 52% of boys and 57% of girls had cholesterol levels exceeding the National Heart Foundation's designated "desirable" level of 4.5 mmol/L for children. CONCLUSIONS: The distribution of cholesterol levels in Australian children compares unfavourably with distributions in children in countries with low rates of cardiovascular disease and indicates a need for widespread, appropriate diet and lifestyle changes.

Australia↗
PubMed1991

Urinary catecholamines, plasma insulin and environmental factors in relation to body fat distribution.

The relationship of body fat distribution to insulin and the catecholamines, hormones that affect lipolysis differentially by fat site, was examined within an environmental context, including factors of medication use, physical activity, dietary intake, educational attainment, and age. Four cross-sectional body fat areas (cm2) were determined by three computed tomography (CT) scans (subcutaneous chest fat at the level of the nipples, subcutaneous and intra-abdominal fat at the level of the umbilicus, and subcutaneous left mid-thigh fat) in 191 second-generation Japanese-American men aged 45-74 years. The site-specific fat measurements were first examined in relation to use of beta-adrenergic antagonists, then to fasting plasma insulin and C-peptide levels and to urinary epinephrine and norepinephrine levels from a 24-h urine collection made during usual daily activities. Greater fat stores in the intra-abdominal area, even after adjustment for body mass index (BMI, weight/height2) and presence of coronary heart disease, were found to be related to use of beta-adrenergic antagonists. In men taking no adrenergic antagonists (n = 157), after adjustment for BMI, truncal fat measurements of the chest (partial r = -0.16, P less than 0.05) and intra-abdominal area (partial r = -0.21, P less than 0.05) were found to be inversely related to epinephrine, and intra-abdominal fat (partial r = 0.25, P less than 0.01) alone was directly related to fasting plasma insulin. With respect to other environmental variables, the significant inverse relationship of intra-abdominal fat (adjusted for BMI) with physical activity (partial r = -0.17, P less than 0.05) and the significant difference in intra-abdominal fat by educational attainment (college 102.3 +/- 5.7 vs no college 115.7 +/- 6.1 cm2, P = 0.03) became non-significant with adjustment, using multiple regression analysis, for insulin in the case of physical activity and epinephrine in the case of educational attainment. Thus, intra-abdominal fat showed a unique set of relationships to metabolic parameters which could be further related to certain environmental variables.

Adipose Tissue↗
PubMed1989

Determinants of blood pressure in childhood and adolescence.

Relationships between blood pressure and dietary factors were investigated in 434 boys and 450 girls aged 9 years. Dietary data were obtained from a food-frequency questionnaire which was completed by parents. This was used to estimate daily energy intake and the intake of 14 nutrients considered likely to influence blood pressure. Blood pressure was tested for relationships to absolute and calorie-adjusted intakes of each nutrient after adjustment for age, weight, height, socio-economic status and the month of examination. Ambient temperature was the most important determinant of blood pressure, an increase of 10 degrees C being associated with a 6-7 mmHg fall in blood pressure. Diastolic blood pressure in boys was negatively related to energy intake and to calorie-adjusted fibre intake. Mean adjusted diastolic blood pressure in boys in the top fibre intake quartile was 2.5 mmHg lower than that in the lowest quartile. Systolic blood pressure in girls was negatively related to calorie-adjusted intakes of protein. There were no relationships between blood pressure and calorie-adjusted intakes of fats, carbohydrates, sodium, potassium, calcium or magnesium.

Adolescent↗
PubMed1989

A comparison of methods of dietary assessment in Australian children aged 11-12 years.

A total of 225 children attending year 7 classes in state primary schools in Perth, Australia, participated in the study. Nutrient intakes were determined by a number of low-intensity methods and compared with intakes determined by a reference method based on 14 24-h diet records collected over several months and covering each day of the week twice. The low-intensity methods were (i) a food frequency questionnaire (FFQ) administered to the children in school, (ii) the same FFQ administered to the children's parents by post and (iii) a small number (one, two or three) of 24-h diet records completed by the children. The FFQ included 175 food items, the time frame was 'during the previous week' and information on size of servings was not requested. The results indicated poor agreement between the reference method and the FFQ methods. In contrast, agreement between the reference method and methods based on two or three diet records in the series was relatively good.

Australia↗
PubMed1988

Diet and blood pressure in 9-year-old Australian children.

Relationships between blood pressure and dietary factors were investigated in 884 9-y-old Australian children. Data on usual diet were obtained from a food frequency questionnaire completed by parents. The data were used to estimate daily energy intake and intakes of 14 nutrients considered to have some potential for influencing blood pressure. Systolic and diastolic blood pressure were tested for relationships with absolute intakes and calorie-adjusted intakes of each nutrient after adjustment for potential confounders. Diastolic pressure in boys was negatively related to energy intake and to calorie-adjusted fiber intake. Mean adjusted diastolic pressure in boys in the top fiber-intake quartile was 2.5 mm Hg lower than that in the bottom fiber-intake quartile. Systolic pressure in girls was negatively related to calorie-adjusted intakes of protein and cholesterol. There were no detectable relationships between blood pressure and calorie-adjusted intakes of fats, carbohydrates, sodium, potassium, calcium, or magnesium.

Australia↗
PubMed1976

Studies on low-dose oral contraceptives: cervical mucus and plasma hormone changes in relation to circulating D-norgestrel and 17alpha ethynyl-estradiol concentrations.

A study was undertaken to determine the effects of a low-dose oral contraceptive comprising 150 mug of D-norgestrel and 30 mug of 17alpha-ethynyl estradiol (Microgynon) on the plasma levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17BETA-ESTRADIOL, AND PROGESTERONE AND ON THE PHYSICAl properties of cervical mucus. Samples of blood and cervical mucus were obtained from three women during a treated cycle and the immediately-following "withdrawal" cycle. Specific radioimmunoassay methods were used to determine LH, FSH, 17beta-estradiol, and progesterone levels in treated and withdrawal cycles, and D-norgestrel and 17alpha-ethynyl estradiol in samples obtained during treated cycles. The concentration of synthetic steroids was also measured in blood samples obtained before and 1 hour after ingestion of the contraceptive to determine the maximal daily variation. The results indicated that the contraceptive action of this combined low-dose oral contraceptive is mediated through suppression of ovulation and by rendering the cervical mucus impenetrable to sperm. Plasma FSH levels appeared to be one of the most sensitive indices of suppression. Determination of D-norgestrel and 17alpha-ethynyl estradiol showed that 3 to 4 days were required to reach maximal plasma levels and that daily fluctuations were considerable. Withdrawal of the pill resulted in an immediate return to ovulatory cycles in all three subjects studied.

Biological Clocks↗
PubMed1976

Plasma hormone levels and the incidence of carcinogen-induced mammary tumours in two strains of rat.

The incidence of mammary tumours developing after administration of the carcinogen DMBA (at 50 days of age) has been determined in 2 strains of Sprague-Dawley rat. Untreated animals of each strain were exsanguinated in dioestrus at a time corresponding to the early post-carcinogen stage (at 70 days of age) and the plasma concentrations of prolactin, oestradiol-17B and progesterone were measured by radioimmunoassay. In an inbred strain of rats, tumour-induction rate was 6-4% and plasma prolactin concentration was 2-5 x lower than that found in a random-bred strain with a tumour-induction rate of 41-6%. No difference was found between the 2 strains in the level of either ovarian hormone. It is concluded that the difference between these strains in mammary gland susceptibility to DMBA may be related to plasma prolactin concentration, but it is unlikely to be determined by the ovarian hormones.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1975

Ileocaecal tuberculosis.

This report is of a single case of ileocaecal tuberculosis presenting as subacute bowel obstruction, with clinical features suggesting an inflammatory cause. The diagnosis of tuberculosis was made at operation although tuberculosis was suspected beforehand. Treatment consisted of triple therapy only and appeared to be successful in so far as loss of symptoms resulted.

Adult↗
PubMed1975

Influence of anti-oestrogens on the specific binding in vitro of (3H)oestradiol by cytosol of rat mammary tumours and human breast carcinomata.

The anti-oestrogenic potential of two nitrogen-mustard-containing compounds, I.C.I. 79792 and I.C.I. 85966, was studied. I.C.I. 85966 usually did not decrease specific binding of [3H]oestradiol by breast-tumour cytoplasmic proteins. I.C.I. 79792 decreased specific [3H]oestradiol binding, but not to the same extent as similar concentrations of I.C.I. 46474, diethylstilboestrol or dibutyldihydrostilboestrol.

Animals↗