The Effect of Acute and Chronic Exercise on Thyroid Hormones in Obesity

Abstract Thyroid hormones were measured before, during and after acute exercise (60 min) or physical training (3 months) in obese women. Thyroid stimulating hormone concentration increased during acute work and decreased immediately after. No changes were seen during the two following days. An increase was seen after ten days as well as after three months of physical training. Thyroxine concentrations showed no changes. 3,5,3′-Triiodothyronine decreased slightly immediately after acute exercise, and after three months of physical training, 3,3′,5′-triiodothyronine (reverse triiodothyronine) increased slowly during and after acute exercise. A negative correlation was found between changes in fasting insulin and thyroxine and a positive correlation between changes in blood pressure and triiodothyronine after training. Lack of agreement in previous reports is probably due to methodological differences such as methods more or less susceptible to fatty acid interference, and thyroid hormones changing differently during acute work and before and after physical training. The duration of the study may also be of importance, even 3 months possibly being too short for attaining equilibrium in thyroid homeostasis.     

Cytokine responses to the native and recombinant forms of the major surface glycoprotein of Pneumocystis carinii

Pneumocystis carinii is a major opportunistic pathogen and leading cause of morbidity in patients with AIDS. The major surface glycoprotein (MSG) of P. carinii, represented by a family of related proteins encoded by unique genes, is highly immunogenic and contains T cell-protective epitopes. We undertook the present study to define the CD4 T helper (Th) response by cytokine secretion to native MSG and a recombinant form of the protein, MSG-B. Spleen cells were collected from Lewis rats and restimulated with both native MSG and MSG-B. Within 24 h, the CD4 cells secreted high levels of interferon-gamma (IFN-γ) in response to both types of antigen, indicative of a Th1 response; however, after 72 h of incubation, only the native MSG stimulated secretion of IL-4 (Th2 response) from the cells. We then investigated whether the presence of IL-4 could alter the predominant Th1 phenotype by the CD4 cells in response to MSG and MSG-B. Cells cultured with native MSG and IL-4 produced low levels of IFN-γ and elevated levels of IL-4. Interestingly, cells incubated with MSG-B and IL-4 reduced production of IFN-γ, but were not stimulated to produce increased levels of IL-4. The presence of anti-IFN-γ antibody in the MSG- or MSG-B-stimulated cultures did not effect the expression of IFN-γ mRNA, suggesting that the generation of Th1 cells in response to MSG or MSG-B was not dependent on IFN-γ. We conclude that native MSG, which contains multiple forms of this antigen, and recombinant MSG elicit different cytokine responses in vitro. These data are not only important to studies of MSG, but may also be relevant to the role of MSG in the immunopathogenesis of P.carinii infection in vivo.     

Effect of Morphine and Naloxone on Stimulated Gastric and Pancreatic secretion

The effect of morphine and naloxone on gastric and pancreatic secretion was investigated. Morphine inhibited pentagastrin stimulated gastric acid secretion. This effect was reversed by naloxone while naloxone alone had no effect on acid secretion. Neither morphine nor naloxone altered secretin stimulated pancreatic secretion.     

Non‐invasive positive pressure ventilation during sleep at 3800 m: Relationship to acute mountain sickness and sleeping oxyhaemoglobin saturation

Background and objective: Ascent to high altitude results in hypobaric hypoxia and some individuals will develop acute mountain sickness (AMS), which has been shown to be associated with low oxyhaemoglobin saturation during sleep. Previous research has shown that positive end‐expiratory pressure by use of expiratory valves in a face mask while awake results in a reduction in AMS symptoms and higher oxyhaemoglobin saturation. We aimed to determine whether positive pressure ventilation would prevent AMS by increasing oxygenation during sleep. Methods: We compared sleeping oxyhaemoglobin saturation and the incidence and severity of AMS in seven subjects sleeping for two consecutive nights at 3800 m above sea level using either non‐invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of AMS were assessed by administration of the Lake Louise questionnaire. Results: We found significant increases in the mean and minimum sleeping oxyhaemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO₂ was lower in subjects who developed AMS after the night spent without positive pressure ventilation. Conclusions: The use of positive pressure ventilation during sleep at 3800 m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO₂. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation.     

Quantitative production of prostaglandin E2 and its metabolites by human fetal membranes

Summary. Cultured amnion, choriodecidua and intact fetal membrane produced similar quantities of prostaglandin E₂ (PGE₂) (1–5 ng/ml). Choriodecidua and intact fetal membrane also produced very high levels of PGE₂ metabolites (100–1000 ng/ml). The total production of PGE (PGE₂ metabolites) was similar in intact fetal membrane and in choriodecidua, suggesting that the amnion, although a source of PGE₂ contributes little to the overall PGE production by fetal membranes.