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The short stature of the African pygmies is due to complex interactions between the genetic potential, hormones, nutrition, and environmental factors rather than a defect in their systemic growth hormone-insulin-like growth factor I (IGF I) axis. The serum IGF I and IGF binding protein (IGFBP-3) content of the pygmies is similar to that of Europeans and Bantus. The pygmies have a high level of immunoglobulins, which indicates that the low circulating levels of IGF-I and IGFBP-3 are due to exposure to environmental infections.

Sickle cell trait (SCT) is a genetic disease affecting the synthesis of normal hemoglobin (Hb) marked by the heterozygous presence of HbA and HbS. It is thought that exercise tolerance and aerobic capacity could be limited in SCT carriers, but that the co-existence of a-thalassemia with SCT (SCTAT) could improve exercise response. To examine these issues, we compared the characteristics of VO2 kinetics during a constant heavy exercise among athletes carrying either the SCT (n = 6), the SCTAT (n = 9), or the normal Hb (control group: n = 10). After determination of maximal power output (Ppeak), all subjects underwent a constant heavy cycling exercise lasting 9 mm at ~70% Ppeak. Pulmonary VO2 and cardio-respiratory parameters were measured breath-by-breath and the VO2 response was modelled using non-linear regression techniques. The time constant of the VO2 primary component and oxygen deficit were not significantly different among the three groups. The VO2 slow component was 28% and 33% higher (p <0.05) in SCT and SCTAT than in the control groups, respectively. Altogether, athletes with the SCT and the SCTAT had higher heart rate at the beginning (+ 5.2%) and the end (+ 7.4%) of the slow component compared to the control group (p <0.05). These results suggest that SCT and SCTAT subjects are not limited during the first exercise minutes, but are prone to exercise intolerance and to lower aerobic capacity thereafter, due to a higher VO2 slow component, and that α-thaIassemia does not improve exercise response. The finding of a higher slow component in SCT and SCTAT athletes was possibly due to the loss of O2 availability to muscles, additional fiber recruitment and/or higher cardiac load with time. [ABSTRACT FROM AUTHOR]

Sickle cell trait (SCT) is a genetic disease affecting the synthesis of normal haemoglobin (Hb) and marked by the heterozygous presence of HbA and HbS. Some studies have suggested that SCT carriers might be prone to vascular alterations, cardiac ischaemia and arrhythmias leading, in some subjects, to sudden death. It is well known that a loss or a disequilibrium of autonomic activity are powerful predictors of sudden cardiac death. We hypothesized that SCT subjects might exhibit alterations in the activity of the autonomic nervous system that could constitute further risk factors for cardiac complications. Resting haemorheological parameters (eta(b), blood viscosity; eta(p), plasma viscosity; Hct, haematocrit; Tk, red blood cell rigidity), and sympathetic and parasympathetic indices of nocturnal autonomic activity (temporal and frequency analysis of heart rate variability) were thus compared between a group of nine SCT subjects and a group of nine control subjects. eta(b) was higher in the SCT group than in the control group while Hct, eta(p) and Tk were not different. Global variability (SDNN, SDNNIDX) and parasympathetic (PNN50, RMSSD, HF) indices were significantly lower in the SCT group compared with the control group, while the LF/HF ratio was highly increased, underlining a major sympathetic shift. The autonomic imbalance in SCT subjects was mainly related to lowered parasympathetic activity. Thus, our study suggests an additional global decrease and imbalance of autonomic nervous system activity to biological disorders of SCT carriers, that may constitute further risk factors for cardiac complications in this population.

This study examined spectral components of heart rate variability (HRV) during endurance mountain running in 8 healthy trained subjects. The data showed that during this type of mountain running, all spectral components of HRV may severely decrease, particularly very-low-frequency and low-frequency (LF) power, suggesting extreme activation of the sympathetic nervous system. The physiologic response of the heart in this situation was the downregulation of the beta-adrenergic receptors to protect myocardial function, with a subsequent increase in parasympathetic tone, reflected by an increase in high-frequency (HF) power and a decrease in the LF/HF ratio.

In August 1986, gases from the Nyos volcanic lake killed 1,746 persons in northwestern Cameroun, but 1,500 others living in the affected area survived. Gas emanations contained carbon dioxide, sulfur dioxide, and hydrogen sulfide. The objective of this study was to evaluate the delayed respiratory consequences of the inhalation of such volcanic gases. Two groups of subjects living in the same area, exposed (Nyos group; n = 381) or not exposed (control group; n = 128) to Nyos gases, were evaluated with a short questionnaire and by measurement of peak expiratory flow (PEF, percent predicted) in March 1991. Eleven percent of the subjects smoked, more often men than women (23% vs 4%; p < 0.001). In the whole population (exposed and unexposed), smoking was associated with a 3.6-fold increase in the frequency of cough (p < 0.001) and with a 6-fold increase in the frequency of sputum production (p < 0.005), but not with a decrease in PEF. There was no difference in the frequency of dyspnea, cough, sputum production, and PEF between Nyos and control groups. We conclude that 55 months after the emanation of gases from Nyos volcanic lake, there was no difference in respiratory symptoms, and PEF between survivors who inhaled volcanic gases and control subjects, whereas smoking was associated with cough and sputum production.

We investigated the effects of preliminary exercise (muscular warm-up) on body temperature, water loss and physical performance during consecutive sustained exercise. Thirty-one untrained men aged 21 to 30 years old (mean 25.12 +/- 2.92) were subjected to two physical trial tests at 75% Pma. One trial. (T - PE) was performed without preliminary exercise (PE) and the other (T + PE) was preceded by 15 minutes of preliminary exercise performed at 50% Pma. The trials involved pedaling an ergocycle until exhaustion, followed by a 30 minutes period of inactive recovery. The rate of increase of body temperature during the work consecutive to preliminary exercise (T + PE) was lower than that of the work without preliminary exercise (T - PE). The energy output and water loss during T + PE were significantly (P < 0.01) greater than during T - PE. However, the body temperatures at the end of the two tests were identical. The rate of decrease of body temperature, measured after 30 minutes of recovery, was higher for T + PE than T - PE. The duration of work was increased by PE for 25 (80.65%) subjects and decreased for 6 (19.35%). We conclude that preliminary exercise allows better adjustment of thermohydric regulation by moderating the rise in body temperature and increasing water loss during physical work. For most subjects, these adjustments allow improved endurance.

The health requirements of pygmies is poorly understood because of their continued isolation from the other tribes in Central Africa. This study was undertaken among the Baka pygmies of the Eastern Province of Cameroon to generate basic health data among them. A total of 141 adults (18-45 years) were tested for the hepatitis B surface antigen (HBsAg), antibody to the surface antigen (anti-HBs), antibody to the core antigen (anti-HBc) and antibody to the hepatitis C virus (anti-HCV). All HBsAg-positive sera were tested for the hepatitis B e antigen (HBeAg) and antibody (anti-HBe). The presence of antibodies to the hepatitis D virus was determined in most of the anti-Hbs-positive sera, and some of the HBsAg-positive sera. In addition to these, previous infection with syphilis, measles, HIV 1/2 and HTLV were determined by looking for the specific antibodies. We found HBsAg in 14.2% (20/141), anti-HBs in 93.6% (132/141), anti-HBs in 52.2% (73/140), anti-HCV in 7.9% (11/139, measles antibody in 99.3% (139/140), antibody to Treponema pallidum in 13.4% (18/134), antibody to HTLV-1 in 10.9% (15/138) and antibody to HIV-1 in 0.7% (1/140) of the sera tested.