General practitioners in the Western Metropolitan Health Region of Sydney

A comprehensive survey of the number of general practitioners in the Western Metropolitan Health Region of Sydney identified 753 general practitioners with one or more practice locations in the region; this was the equivalent of 711 full-time general practitioners, and represented a general practitioner-population ratio of 1:1533.

Comparative human oral clinical pharmacology of cefadroxil, cephalexin, and cephradine

At equivalent oral doses, cefadroxil has a longer serum half-life, slower urinary excretion rate, greater area under the serum level versus time curve than cephalexin or cephradine, and peak serum concentrations that are 75 to 80% those of cephalexin. The calculated, apparent in vivo volume of distribution of cefadroxil is greater than that of cephalexin. These properties infer greater persistence of cefadroxil in serum and urine and more prolonged in vivo bacterial exposure to cefadroxil than to cephalexin or cephradine. Neither cefadroxil nor cephalexin demonstrates drug accumulation on repeated administration. The serum levels achieved by cefadroxil are unaffected by food. The pharmacokinetic properties of cefadroxil are supportive of the development of clinical efficacy data which could indicate that cefadroxil could be administered at 12-h intervals.

Physical fitness levels vs selected coronary risk factors. A cross-sectional study

Several studies show significant correlations of blood variables, weight, abnormal electrocardiograms, and blood pressure with the incidence of coronary heart disease, but the quantification of fitness and its correlation with coronary heart disease is more difficult. In this study, approximately 3,000 men, average age of 44.6 years, were examined for blood and lipid profile, pulmonary function, percent body fat determination, and Balke maximal performance treadmill stress testing with multilead ECG monitoring. Five age-adjusted cardiorespiratory fitness categories were determined from treadmill times. A consistent inverse relationship among physical fitness categories and resting heart rate, body weight, percent body fat, serum levels of cholesterol and triglycerides, glucose, and systolic blood pressure, was observed. Forced vital capacity was directly related to levels of fitness. These results, although cross-sectional, imply that physical fitness is related to lower coronary risk factors.

The measurement of muscle mass in children using [15N]creatine

In eight infants and children who had recovered from protein-energy malnutrition (PEM), muscle mass was estimated by measuring creatine turnover by an isotope dilution technique using [15N]creatine, creatine concentration, and urinary creatinine output. Creatine turnover varied from 1.5 to 2.6% of the muscle creatine pool per day and muscle creatine concentration ranged from 1.7 to 3.9 mug/mug muscle mass was between 15% and 37% of total body weight. The results indicate that daily creatinine output is not a reliable indicator of muscle mass in children who have recently recovered from severe PEM.

Prediction of body density in young and middle-aged men

The purpose of this investigation was to predict body density of young (18-22 yr) and middle-aged (40-55 yr) men and to determine if generalized equations were appropriate to both populations. The dependent variable, body density, was determined by the hydrostatic technique. Independent variables included 7 skinfold fat, 11 girth, and 7 diameter measures; age; height; and weight. Mean body density for young men was 1.068 g/ml (SD +/- 0.014) and percent fat, 13.4 (SD +/- 6.0); the values for middle-aged subjects were 1.043 g/ml (SD +/- 0.0130) and 24.7% (SD +/- 5.9). Incomplete principal components analysis was used to examine the dimensions measured by the independent variables, and these analyses revealed differences between samples. Using multiple regression analysis, with the exception of girth measurements, the slopes of the regression lines were equal. For all analyses, however, the intercepts were different. These results confirmed the need for different regression equations for these populations. The most accurate prediction for young men was with two skinfold, four girth, and two diameter measures (R = 0.88; SE = 0.0069 g/ml); two skinfold and three girth measures accurately predicted body density for middle-aged men (R = 0.84; SE = 0.0074 g/ml).

Alkylation of meseenger RNA by dimethylnitrosamine

Rats were treated with radioactive dimethylnitrosamine or methyl methanesulphonate and the alkylation of various RNA fractions was determined 4 h later. It was found that after administration of dimethylnitrosamine, hepatic messenger RNA (isolated by binding to oligo(dT)-cellulose) and nuclear RNA were alkylated slightly, but significantly less than ribosomal RNA. After treatment with methyl methanesulphonate nuclear RNA was alkylated to a greater extent than either messenger or ribosomal RNA. The implications of these findings with respect to the mechanism by which dimethylnitrosamine inhibits liver protein synthesis are discussed.

Prediction of body density in young and middle-aged women

The purpose of this investigation was to predict body density of young and middle-aged women and to determine if the use of a greater variety of variables, particularly those for fat in the bust and hip regions, increases the predictability of body density. Body density determined by the hydrostatic technique (dependent variable) was obtained from 83 volunteer young women and 60 middle-aged women ranging from 18 to 22 and 33 to 50 yr of age, respectively. Independent variables included 8 skinfold, 13 girth, and 7 diameter measures; age; height; weight; and bra and cup sizes. Mean body density for young women was 1.043 g/ml (SD plus or minus 0.014) and percent fat, 24.8 (SD plus or minus 6.4); 1.031 g/ml (SD plus or minus 0.015) and 29.8% (SD plus or minus 6.7) for middle aged subjects. Percent fat was calculated by the formula of Siri. Factor analysis was used to examine the dimensions measured by the independent variables as a function of age. A multiple regression model was used to develop predictions of body density from the independent variables. The best combination of four variables for predicting body density was skinfold thigh, skinfold suprailiac, cup size, skinfold suprailiac, girth waist, and skinfold thigh (R = 0.89) for middle-aged women. The data showed that the highest predictons were found by using combinations of skinfold, girth, and diameter variables; cup size also supported the need for different regression equations for different age groups.

Renin and acute circulatory renal failure in the rabbit

Plasma renin concentration (PRC) was measured in 25 rabbits before and 6, 24, or 72 hours after subcutaneous injection of glycerol. Renal failure and tubular necrosis developed in most animals and PRC rose sixfold to a maximum at 24 hours. Small insignificant changes of PRC were present at 6 and 72 hours. None of these changes was observed in a control group of nine animals killed 24 hours after an injection of saline. The amount of renin extractable from single superficial glomeruli and from renal cortical tissue was reduced after injection of glycerol. In a second study of 11 anesthetized rabbits, renal venous PRC increased on average from 151 to 1810 units/liter following a 4-hour period of renal artery occlusion. Arterial PRC did not change significantly during this time, but the kidneys showed histological changes of acute tubular necrosis. These experiments are compatible with the suggestion that renin is involved in the pathogenesis of acute circulatory renal failure.