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Biomedical subjects

J F Andrews

Publications and source records attributed to J F Andrews.

At least 19 recordsLinked to original sources
PubMed1992

An assessment of the thermogenic effects of fluoxetine in obese subjects.

Fluoxetine is an antidepressant drug with weight reducing properties. To assess whether fluoxetine has an ability to promote diet induced thermogenesis (DIT), 30 obese subjects (BMI 30-45 kg/m2) underwent a double blind, randomized, cross-over trial of 60 mg fluoxetine versus placebo. A two week single blind, run-in period on placebo was incorporated into the study to allow for placebo responders. The first stage of the study lasted for 14 days followed by a six week cross-over wash-out phase and concluded with the second 14 day stage of the study. An estimate of resting metabolic rate (RMR) was measured by continuous indirect calorimetry using the ventilated hood technique. Metabolic measurements were performed on six occasions, immediately before the first tablet was taken in the first stage, 24 hours after the first tablet was consumed and on the last day of the first stage; these three recordings were repeated on the second stage of the study. On each occasion a control reading of RMR was taken for 30 minutes then DIT was measured for 90 minutes following a lemon and glucose drink (1 g/kg body weight). Whilst a significant weight reduction (1.16 kg, P less than 0.05) occurred in the active stage, no such effect was achieved in the placebo phase. No differences were found between the two stages with regard to RMR, total DIT, peak DIT and time taken to reach peak DIT. We conclude that fluoxetine does not stimulate metabolism and that the weight reduction after 14 days therapy is due to other mechanisms.

Adult↗
PubMed1991

Strategy usage among deaf and hearing readers.

High school youths who were prelingually and profoundly deaf, hearing elementary-school-age youths, and hearing reading-disabled high school youths read expository texts and filled in deleted words and phrases. After making word replacements, they explained their decisions in sign or verbally. As expected, the hearing youths had an easier time filling in the deleted portions and explaining what strategies they were using. While the deaf youths reported using similar strategies as the hearing youths, the frequency of each type of strategy differed. Deaf readers more often relied on rereading and background knowledge, while the hearing readers made greater use of context clues. The results suggest that instruction for deaf readers should include more effective comprehension strategies.

Adolescent↗
PubMed1990

Brown adipose tissue lipid is the main source of energy during arousal of the golden hamster (Mesocricetus auratus).

1. Male golden hamsters were induced to hibernate. 2. During stimulated arousal (i) the time course of increase in deep body temperature was related to the time-course of increasing oxygen consumption and (ii) brown adipose tissue lipid content was determined at several time points. 3. In early arousal (0-30 min) more lipid was mobilised (14.6 kJ) than was utilised in metabolism (3.5 kJ). BAT lipids accounted for 88% of the total energy requirement of arousal (90 min). 4. We conclude that BAT not only supplies heat for arousal but fuel for other arousing tissues.

Adipose Tissue, Brown↗
PubMed1989

New outlook on pericardial substitution after open heart operations.

The difficulties of reoperation owing to adhesions are well known. Clinical attempts to solve this problem using synthetic materials or glutaraldehyde-fixed pericardial xenograft have been less than satisfactory. Although experimental animal results have been good, they have not considered the influence of cardiopulmonary bypass (CPB) on adhesion formation. This study addressed the influence of CPB on the formation of adhesions and evaluated biodegradable polyglycolic acid as a material to reduce adhesions and as a pericardial substitute. Forty-five weanling sheep received implants of pericardial xenograft and polyglycolic acid with and without CPB. The pericardial xenograft showed no adhesions when implanted without CPB, but severe adhesions formed and a thick fibrinous layer covered the heart when CPB was used, making identification of coronary arteries at reoperation very difficult. The polyglycolic acid mesh implanted without CPB was absorbed and replaced with newly formed host collagen. With CPB, the polyglycolic acid was more rapidly absorbed, and a thinner layer of host collagen formed. Therefore, future animal studies must include CPB. In agreement with reported clinical results, glutaraldehyde-fixed pericardial tissue implanted with CPB resulted in severe epicardial reaction and therefore is not an ideal pericardial substitute.

Animals↗
PubMed1988

Effect of cold rearing on metabolic rate and growth rate of obese (ob/ob) mice.

Oxygen consumption, total body mass, and body fat content were measured in lean and obese animals housed from birth at either 17 +/- 2 or 28 +/- 2 degrees C. Results for each of the three parameters were recorded at three time points 26, 35, and 56 days of age. The experiments demonstrate that at both ambient temperatures oxygen consumption expressed per kilogram body mass is consistently greater in lean animals. In all animals oxygen consumption (ml/kg/min) falls between 26 and 56 days, but significantly so in obese mice at 17 degrees C. There is no difference in age-related reduction of oxygen consumption between the genotypes at 28 degrees C; cold environment also significantly impairs growth of obese animals but not of lean ones. Contrary to those at 28 degrees C obese mice at 17 degrees C do not differ significantly in body weight from lean controls by 56 days of age. Carcass fat is consequently reduced in cold-reared obese mice compared to warm-reared obese, when expressed as grams of fat. When expressed as percentage fat, cold-reared lean and obese mice have less fat at 56 days.

Adipose Tissue↗
PubMed1986

Brown adipose tissue thermogenesis during pregnancy in mice.

The thermogenic activity of interscapular brown adipose tissue has been assessed at different stages of pregnancy in mice. In late pregnancy there was a hypertrophy of the tissue which reversed at parturition. Neither the total protein content nor the total cytochrome oxidase activity of the tissue changed significantly throughout pregnancy or into early lactation (2-3 days, post-partum). However, mitochondrial GDP binding, an index of the activity of the proton conductance pathway, was significantly decreased at the end of pregnancy with a further decrease in early lactation. Moderate food restriction had no effect on either cytochrome oxidase activity or mitochondrial GDP binding at the end of pregnancy, as compared with pregnant animals fed ad libitum. Food restriction did, however, prevent the hypertrophy of brown adipose tissue in late pregnancy. It is concluded that brown adipose tissue thermogenesis is not significantly decreased in the pregnant mouse until shortly before parturition, even in animals subject to food restriction. It is also concluded that the normal dietary stimulation of thermogenesis in response to hyperphagia is suppressed in the pregnant animal.

Adipose Tissue, Brown↗
PubMed1985

Low doses of T3 induce a rapid metabolic response in young lambs.

Injection of 1 microgram/kg T3 resulted in an increase in metabolic rate (VO2) within an hour of administration to lambs (aged 27 to 180 h). A larger dose of 5 micrograms/kg T3 initially caused a slight inhibition of VO2, which was followed in the second post-injection hour by a significant increase. The increase in VO2 during the second post-injection hour after either 1 microgram/kg or 5 micrograms/kg T3 represented a rise of 22% above pre-injection VO2. The increase persisted and was slightly enhanced during the third post-injection hour. These changes were significantly greater than the smaller changes which followed control injection (P less than 0.005). No significant changes in Tre or Tesk occurred after any treatment. This rapid response to low, physiological doses of T3 emphasises a possible role for thyroid hormones in the short-term control of metabolism in young animals.

Animals↗
PubMed1985

Administration of low doses of TSH result in a rapid increase in the metabolic rate of young lambs.

A low dose of TSH (Thyroid Stimulating Hormone) can induce a rapid increase in VO2 and the response is dose dependent. Lambs aged 36 to 289 h were used. 5.0 i.u./kg TSH, the highest dose used, caused an initial inhibition of response but during the second and third post injection hours VO2 increased to control level. The intermediate TSH dose, 1.0 i.u./kg TSH resulted in a clear increase in VO2 even in the first post-injection hour, which further increased in the second and third hours. This change was significantly greater than in controls. Animals treated with the lowest dose, 0.5 i.u./kg TSH divided themselves into 2 distinct populations: responders, where an immediate and significant increase in VO2 occurred and non responders, where a small inhibition of metabolism was evident. The responder group had a significantly lower pre-injection VO2 and a significantly lower mean body weight, than the non responders. In the responders, the stimulation of metabolism was greater than at either of the higher TSH doses. These results indicate that low, but not high doses of TSH induce a rapid metabolic response. The argument in favour of a short-term role for thyroid hormones is thus strengthened.

Animals↗
PubMed1985

Thyroid hormones in rats during long-term cold exposure and hypometabolic effect of reverse triiodothyronine on adrenaline induced thermogenesis.

One-day cold exposure to 5 degrees C induced temporal increase of reverse-triiodothyronine (rT3), triiodothyronine (T3) and thyroxine (T4) concentrations in the blood of rats (by 151%, 91% and 107%, respectively). The levels of all thyroid hormones remain elevated for at least 10 days of cold exposure. The injection of rT3 (330 micrograms kg-1 s.c.) inhibited the resting and adrenaline stimulated metabolism 1-3 days after application independently from the thyroid status of the animals. Since the hypothermic effect of rT3 occurred in thyroidectomized rats, it was concluded that rT3 acted primarily on peripheral, tissues, rather than on the thyroid.

Animals↗