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    Radio-immunoassays of anabolic hormones in young ruminants : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University
    (Massey University, 1978) Bohn, Griselda Margaret
    Four experiments with young calves and one with ewes and lambs are described, all of which involved taking blood samples via a jugular catheter. Plasma samples were all assayed for insulin and growth hormone by radio-immunoassays. In Experiments 1 - 4. prolactin assays were also carried out, and results of plasma glucose assays were presented for Experiments 2 - 4. In Experiments 1 and 5, the effect of suckling on starved calves and lambs was investigated. Insulin rose from <1 ng/ml to 2 - 7 ng/ml after suckling. Growth hormone and prolactin did not change systematically in any way after suckling in calves, but lambs' growth hormone levels increased from <2 ng/ml to >10 ng/ml at the onset of suckling, as did the GH levels in plasma of their dams. In Experiments 2 and 4, the effect of changing plasma energy substrate levels was investigated in calves. In Experiment 2, it was observed that a 30-second jugular infusion of either volatile fatty acids in an equimolecular mixture of acetate, propionate and butyrate, or glucose (both administered at 1.25 mM per kg body weight (bw)) resulted in a variable, but significant increase in insulin levels, but had no effect on growth hormone or prolactin. The results of 1.4 mM per kg bw glucose administration in Experiment 4, confirmed those of Experiment 2. Administration of 0.75 U per kg bw of protamine zinc insulin resulted in a prolonged hypoglycaemia, which was achieved more slowly in five-week-old calves than in week-old calves. Growth hormone and prolactin levels did not respond immediately to insulin administration, but after hypoglycaemia had been maintained for 2 - 3 hours, growth hormone levels decreased from 4 - 8 ng/ml to <3 ng/ml in calves of both one week and five weeks of age, and prolactin levels increased slightly. The effect of a 30-second infusion of 0.3 g per kg bw arginine on calves was tested in Experiment 3, and significant increases in all plasma measurements except growth hormone were observed. Increases of both insulin and glucose were higher in five-week-old milk-fed calves than they were in week-old calves or in five-week-old ruminant calves, and in all calves the glucose increase was quickly followed by a decrease in glucose levels to a deep hypoglycaemia. The prolactin response was smaller and more prolonged in week-old calves than in the older calves. Saline which was infused in an equi-osmolar solution to arginine, resulted in decreases in both growth hormone and prolactin. The results of Experiment 3 are contrasted with those of Experiment 5, in which a 0.5 g per kg bw arginine dose was infused over a 30-minute period into ewes and lambs. The insulin responses were smaller then those of calves, but the growth hormone levels increased significantly from <2 ng/ml to >4 ng/ml. In addition to the experimental results described above, radio-immunoassays were described in detail, because all work utilised antibodies raised by the author during the course of study.
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    Some physiological changes in female athletes during and after exercise : investigating the use of a new, low-invasive sampling method (electrosonophoresis) : a thesis in partial fulfilment of the requirements for the degree of Master of Science in Exercise Physiology at Massey University, Palmerston North, New Zealand
    (Massey University. Institute of Food, Nutrition and Human Health, 2003) Purnell, Heather Margaret
    The purpose of this study was to monitor cardiovascular and endocrine changes in sedentary and training females during a six week period, and to assess the accuracy of a new, low-invasive sampling methodology (electrosonophoresis). Changes in fitness were measured using oxygen consumption (VO2). The impact on VO2 of sleep quality, sleep duration and alcohol consumption (recorded in sleep logs) was assessed. Cortisol, testosterone and growth hormone levels in plasma were monitored for acute changes following fitness tests, and chronic changes related to training, oral contraceptive use or alcohol consumption. Hormone concentrations in blood and saliva samples were compared to those in interstitial fluid (obtained using electrosonophoresis) to investigate the accuracy of electrosonophoresis. Mean VO2 increased by 3.3 ± 1.3mL/kg/min between Week 1 and Week 5 and the changes detected in heart rate (HR) during the fitness tests suggest that aerobic fitness of the training participants increased across the study. No significant associations between sleep quality, sleep duration or alcohol consumption and VO2 were detected. No acute changes in plasma hormone concentrations following fitness tests were detected. No chronic changes in plasma cortisol or testosterone concentrations were detected, although a non-significant trend towards increased plasma GH levels in training participants was detected. Resting plasma cortisol levels were significantly lower in oral contraceptive users compared with non-users. Plasma testosterone and growth hormone levels were unaffected by oral contraceptive use. Alcohol consumption had no acute detectable effects on plasma concentrations of the three hormones. Plasma testosterone levels were higher in participants who abstained from alcohol, and higher plasma growth hormone levels were detected in heavy drinkers. These results contrast with published reports. Concentrations of the three hormones in interstitial fluid and plasma exhibited highly significant positive correlations (r2 > 0.98) with an interstitial fluid:plasma concentration ratio of about 1:10 in each case. Equations to predict plasma concentrations of cortisol, testosterone and growth hormone from interstitial fluid concentrations have been derived. The electrosonophoretic method apparently provides an accurate, painless, low-invasive method for prediction of the plasma levels of these three hormones. This technology has far-reaching implications for research in human, animal and biomedical fields.