Variability In Healthy Volunteers Research Articles

Cholesterol and Depression

Several articles have suggested that low total cholesterol levels are linked to changes in behavior; men with low cholesterol levels are associated with higher rates of suicide within 6 years of measurement,¹and lowering the cholesterol levels therapeutically by diets or drugs may lead to a rise in violent deaths.²One explanation for these somewhat disturbing findings is that a low plasma cholesterol level leads to modifications of brain cholesterol concentration that, in turn, alter central nervous function.³Recent findings are highly contradictory, some speaking for^4-6and some strongly against⁷a relationship between blood lipid levels and psychologic variables. In this situation, a clinical study with a lipidlowering agent may lead further than epidemiologic evidence. We have undertaken a small pilot study quantifying psychologic variables in healthy volunteers during and after treatment with a fibrate. Nine healthy individuals gave informed consent to participate (six men

Cholesterol and depression

Several articles have suggested that low total cholesterol levels are linked to changes in behavior; men with low cholesterol levels are associated with higher rates of suicide within 6 years of measurement, 1 and lowering the cholesterol levels therapeutically by diets or drugs may lead to a rise in violent deaths. 2 One explanation for these somewhat disturbing findings is that a low plasma cholesterol level leads to modifications of brain cholesterol concentration that, in turn, alter central nervous function. 3 Recent findings are highly contradictory, some speaking for 4-6 and some strongly against 7 a relationship between blood lipid levels and psychologic variables. In this situation, a clinical study with a lipidlowering agent may lead further than epidemiologic evidence. We have undertaken a small pilot study quantifying psychologic variables in healthy volunteers during and after treatment with a fibrate. Nine healthy individuals gave informed consent to participate (six men

The effect of biologically-active light on the noo- and thymopsyche and on psychophysiological variables in healthy volunteers

The study was carried out to show how bright light affects intellectual mnestic performance alertness, mood and psychophysiological variables in order to understand the mechanism of bright light which is still unclear. 15 healthy normal volunteers (8 males, 7 females) aged 22–34 years (mean 27) participated in the study. Exposure to bright light (2500 lux) or dim light (500 lux) was intermittent for 4 h between 9 a.m. and 5 p.m. Psychometric investigations for assessment of noopsychic variables, such as attention and concentration on the one hand, and thymopsychic variables, such as drive, on the other hand, as well as flexibility and psychophysiological measurements were carried out before, as well as 1, 2, 4, 6 and 8 h after baseline. As compared to the dim-light condition, subjects who were exposed to biologically-active light showed an improvement of noopsyche in the 6th and 8th hour. Also, the subjective thymopsyche revealed an improvement lasting for the whole investigation period. Psychophysiological measurements reflected an improvement of central and autonomous activation, which was parallel to the improvement of cognition and of well-being. However, biologically-active light did not affect flexibility.

Ambulatory pulmonary arterial pressures in humans: relationship to arterial pressure and hormones.

Six healthy volunteers were studied by use of a continuous ambulatory recording technique to document the normal range and variability of pulmonary artery pressure (PAP) and to examine its relationship to systemic arterial pressure (SAP) both at rest and during standardized interventions. Vasoactive hormone levels were measured at frequent intervals. Over 8-10 h of study the mean PAP was 15.7/6.3 mmHg. Parallel changes in PAP and SAP were observed at rest and during exercise and eating. On the contrary, PAP rose and SAP fell with hypoxia, whereas smoking was associated with a rise in SAP but no change in PAP. Sympathetic nervous system activity, as gauged by plasma norepinephrine levels, may have contributed to pressure and heart rate changes during exercise and smoking, but activity of the renin-angiotensin system was not altered by any of the maneuvers. These results provide base-line information on the level of PAP and its variability in healthy volunteers under standardized conditions. Pressures within the systemic and pulmonary circuits change in parallel under some circumstances but move in opposite directions under other conditions.