Effects of exercise on serum cortisol and thyroid hormones.

Serum levels of hydrocortisone, T4, T3 and rT3 were estimated before and after exercise. In group A, untrained young subjects had to cope with a submaximal, fractionated load on a bicycle ergometer. T3 increased, rT3 and cortisol decreased, T4 remained unchanged. Sportsmen in group B accomplished a 10 or 15 km run as a part of their regular training. A rise of cortisol and rT3 was observed, T3 remained unchanged and T4 decreased. In better trained sportsmen the initial level of serum T3 exceeded the upper border of normal values (3.3 nmol/l) and the terminal values of cortisol reached a higher value than in the less trained subjects. It is suggested that the mobilization of fuel from energy stores and the oxidative processes are better regulated in trained sportsmen than in untrained subjects. A sign of the best adjustment to a long run was accompanied by an initial serum T3 above the normal borderline and by a great increase of cortisol after the run.

Effects of total fasting in obese women. IV. Response of serum triiodothyronine (T3) and reverse triiodothyronine (rT3) to administered T3.

Serum levels of T4, T3, rT3, RT3U and TSH were estimated in 12 obese women in the course of a 14-day fasting. Seven of these patients were treated with T3 in a daily dose of 60--80 micrograms. Fasting led to a small increase of serum T4, while fasting combined with T3 administration was accompanied by a small decrease of serum T4. Serum T3 decreased in the course of the first 2 days of fasting to 40--50% of initial values and remained at this low level up to the 15th day of fasting. In the T3 treated group a prompt increase of serum T3 was recorded (+80%), followed by a steady decrease, reaching the control values on day 15, in spite of a continuous T3 administration. Serum rT3 in the untreated fasting group steadily increased up to the 12th day (+43%) and then dropped below the control value (-28%). In the treated group after a non-significant increase (+22%), a decrease of serum rT3 was also observed (-42%). Fasting was accompanied by a tendency to increased serum RT3U values, in the T3 treated group no change occurred. TSH in the untreated fasting women remained practically unchanged while T3 administration was accompanied by a tendency to a transient decrease. The heart rate showed a non-significant tendency to increase in the T3 treated group and the last week of fasting was also accompanied in several patients by a larger weight loss. These results suggest that in addition to an enhanced synthesis of rT3 to the detriment of a decreased production of T3 from T4, an increased catabolism of administered T3 and of endogenous rT3 is involved in a strict calorie restriction. An abortive T3-TRH-TSH feed-back may also operate in these conditions.

Geography and health.

PIP: The most important factors affecting the social, economic, and cultural development are geography, climate, and social fertility. The interaction of these different influences are described, and their relationship with the world's health as shown. Of particular interest is how the introduction of modern techniques can counteract certain of the effects of climatic and geographical factors. Health in the various population groups of the world results from the successive interplay of a long series of factors. Generally, it is known that poverty and ignorance breed disease. Possibly the extent to which economic and educational development is dependent upon climatic and other geographical factors is not fully realized. The distribution of humans over the world's surface is governed by the availability of food and water. Agriculture alone allows the congregation of large populations and the establishment of settled communities, villages, and eventually towns. Social development ensues which may give rise to culture and science. This will allow the birth of industry and the improvement of agricultural techniques. Together they will permit economic development, capable in turn of supporting a competent administration, part of which will cater to the sanitary and medical needs of the community and contribute the health of the population. Apart from the general consequences of living in isolation, or in communities of humankind's social and cultural development, there is also an immediate and direct effect upon health. Complete isolation interferes with the transmission of cultural traditions and with the transmission of most infections. Community life creates chances of mutual infection with resulting immunity. Large cities present many opportunities for acquiring numerous infections and building up resistance to them at an early age. Their endemicity will replace epidemics. The extremely cold climate of the arctic and subarctic regions is usually well tolerated provided deficiency in sunlight is made up of consumption of large amounts of vitamins. The temperate climates are the most favorable to human life. The mild climate is nearly as variable. Hot and dry climates as a rule are well tolerated by humans. Hot and humid climates are less favorable to human well-being and health. Modern transport makes it possible to feed humans in barren areas, to furnish them with comfortable dwellings. New health methods may protect against various germs and parasites of which they would otherwise have been the prey.^ieng

Effects of diet, exercise and anorexigenic drugs on serum thyroid hormones.

The serum levels of T4, T3 and rT3 were estimated in moderately obese women treated with diet (900-1000 kcal) and 4 h of exercise, supplemented with placebo or anorexigenic drugs (phenmetrazine, phentermine and mazindol). After 12 days of treatment, no change in serum T4 occurred in the placebo group (-4%), while in the groups with anorexigenic drugs a significant rise of T4 was observed (phenmetrazine +33%, phentermine +14% and mazindol +20%). Serum T3 decreased significantly in the placebo and the anorexigenic groups to a similar extent (from -21% to -27%) with the exception of mazindol. We did not notice any decrease of T3 in this group (-3%). A rising trend of serum rT3 was observed in all 4 groups, with a statistical significance for mazindol only. It is suggested that 1) a combined energy deficit produced by diet and exercise leads to a pattern of serum thyroid hormones similar to that observed in resting patients on a total fast; 2) the rise of serum T4 after the administration of anorexigenic drugs is due to their sympathomimetic effects; 3) the largest weight decrease observed in the mazindol group (6.7 kg) may be due to the unchanged serum T3 level, while in the other groups a decrease of serum T3 was observed. The lowest weight loss was observed in the placebo group (4.9 kg) with a pronounced decrease of T3 (-24%).

In vitro and in vivo inhibitory effect of dehydroepiandrosterone on respiration.

The inhibitory effect of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEA-S) was tested either in vitro with the use of Clark electrode combined with polarography or in vivo using the Spirolyt apparatus. In vitro, DHEA and progesterone showed a marked inhibitory effect on oxygen consumption by the rat heart liver mitochondria. A decrease of oxygen consumption was also observed with electron transporting particles (ETP). However, in both instances DHEA-S was without effect. In vivo, DHEA inhibited whole body oxygen consumption in rats, provided the steroid was injected in a dose of 50 mg kg-1 and 1--16 h before the measurement. No effect was obtained 9 h after DHEA injected in a dose of 5 mg kg-1. Also DHEA administered per os (25 mg kg-1) for six days was without effect as measured 16 h after the last dose. These data are discussed in connection with the beneficial effect of DHEA-S administered to patients with angina pectoris.