A 62 kDa protein is photoaffinity labelled by [3H]felodipine in vascular smooth muscle, but not in cardiac and skeletal muscle

Irradiation of a cytosolic fraction from vascular smooth muscle in the presence of [3H]felodipine resulted in the labelling of a protein with an apparent molecular weight of 62 kDa. The labelling was seen on UV-irradiation at 360 nm, but not at 254, 278 or at wavelengths above 410 nm. The photolabelling was enhanced in the absence of oxygen. In cytosolic fractions prepared from porcine liver, cardiac and skeletal muscle no photoaffinity labelling of proteins between 90 and 45 kDa could be demonstrated. The results suggest that felodipine is a photoaffinity ligand and that felodipine binds to a soluble protein present in vascular smooth muscle but not in the other tissues tested.     

The relationships of anhedonia and the process-reactive dimension to season of birth and infectious disease incidence in schizophrenia

This project was designed to test two hypotheses drawn from a new formulation explaining the exaggerated winter birthrate among hospitalized schizophrenics. The first is that the supposed exaggerated winter birthrate among process schizophrenics actually represents a reduction in spring-fall births caused by prenatal exposure to infectious diseases during the preceding winter--i.e., a high prenatal death rate in process preschizophrenic fetuses. The second is that the level of negative symptoms in survivors at risk for schizophrenia who were born after winters with high infectious disease rates is exaggerated. The findings provided some tentative support for this formulation. Compared with counterparts born after low-disease winters, schizophrenics born after winters with high disease incidences tended to show lower (more reactive) scores on a measure of the process-reaction dimension but higher anhedonia scores.     

Smoking patterns in the coloured population of the Cape Peninsula (CRISIC study)

A cross-sectional study of tobacco-smoking habits in a random sample of 976 coloured subjects aged 15-64 years revealed that smoking was common, 57% of men and 41% of women being current smokers and 10.4% of men and 9.6% of women having stopped smoking. Heavy smoking prevailed, indicating by mean daily consumption of 14.2 and 13.1 cigarettes among male and female smokers respectively; only 33.5% of male and 39.6% of female smokers used less than 10 cigarettes per day. Coloured smokers smoked more heavily during the weekend. Both men and women smoked mostly filter cigarettes. Forty-four per cent of male and 49.5% of female smokers stated that they had attempted to stop smoking, mainly for health reasons. More than one-third of the participants had a positive attitude to combating smoking, particularly those with an educational level higher than Standard 7. Former smokers and heavy smokers had a significantly higher prevalence of ischaemic heart disease than the other participants. Smoking was associated with a low body mass index, low high-density lipoprotein cholesterol levels, low socio-economic standing, high alcohol consumption and type A coronary-prone behaviour in men. In 1982 the economically active coloured population of the Cape Peninsula spent an estimated R36.2 million on cigarettes.     

Effect of ankle position on isometric quadriceps strengthening

A prospective study of 20 normal subjects was undertaken to determine the effect of three ankle positions (active dorsiflexion, active plantar flexion, natural or rest position) on comfort and facilitation of quadriceps contraction in isometric strengthening in a supine position with the hip and knee fully extended. Surface EMG activity was found to be greatest for the vastus lateralis followed by the vastus medialis and least for the rectus femoris. Equal facilitation was apparent with either active ankle dorsiflexion or plantar flexion. Both were superior to the natural (rest) position. In situations where isometric quadriceps exercises are required, the authors recommend either active ankle dorsiflexion or plantar flexion to facilitate quadriceps strengthening. The choice between the two positions should be based on patient comfort.     

Inhibition by oral N-acetylcysteine of cigarette smoke-induced "bronchitis" in the rat

Specific pathogen-free rats were exposed to the cigarette smoke (CS) of 25 cigarettes daily for 14 days and concurrently given N-acetylcysteine (Nac) as 1% of their drinking water (average daily dose 973 mg/kg). The thickness of the epithelium was measured at four airway levels and the numbers of mucus-containing secretory cells, stained for neutral or acidic glycoprotein (NGP or AGP respectively), were counted in surface epithelium at eight airway levels. Cigarette smoke increased the thickness of the epithelium at three of the airway levels studied by between 37 and 72%. The number of secretory cells was increased at all airway levels distal to the upper trachea by between 102 and 421%. Secretory cells containing NGP were reduced in number but this was more than offset by a large increase in the number of secretory cells containing AGP at all airway levels. N-acetylcysteine inhibited CS-induced epithelial thickening. Nac also inhibited the CS-induced increase in the number of secretory cells with AGP, but had little effect on the CS-induced reduction in the number of cells with NGP. Thus, prophylactic oral N-acetylcysteine led to an overall inhibition of CS-induced mucous cell hyperplasia and epithelial hypertrophy. The results suggest a novel anti-inflammatory action for a drug with known mucolytic effects.     

Exercise intensity, training, diet, and lactate concentration in muscle and blood

With some, but not all, types and intensities of exercise, lactate accumulates in the blood and in the muscles engaged in the exercise. A great deal of attention has been directed towards attempting to understand the dynamics of lactate production and removal at the onset of exercise, during exercise, and during the recovery process following exercise. It has been hoped that an unravelling of these events would provide a key to understanding cellular metabolism and its regulation during exercise. The purpose of this introductory paper to a symposium on lactate is to present a brief overview of some of the conditions that influence the rate and magnitude of lactate accumulation during exercise. It is pointed out that many conditions influence the rate and magnitude of the accumulation of lactate in blood and muscles. Included are diet, state of physical fitness, and the type and duration of the exercise. We have cautioned against trying to evaluate the state of oxygen delivery to muscle and the state of tissue oxygenation from the appearance of lactate in blood. We have pointed out the positive aspects of lactate production based on how it augments the cellular supply of ATP, thereby allowing for high intensity exercise, and also the negative aspects that develop as a result the reduction in pH which adversely influences many cellular processes essential for muscular activity.     

Xylose disposition in humans as a function of age

D-xylose disposition was examined in 24 healthy men between 32 and 85 years of age. Xylose was administered as a 5 gm iv infusion and as a 25 gm po solution. Serum xylose concentrations and urinary excretion of intact xylose were determined. There were statistically significant inverse relationships with age for each of the following parameters after intravenous infusion: elimination rate constant (r2 = 0.71); systemic clearance (r2 = 0.66); renal clearance (r2 = 0.66); and nonrenal clearance (r2 = 0.35). Similar inverse relationships were found after oral dosing for the elimination rate constant (r2 = 0.69) and renal clearance (r2 = 0.54). There was no significant age relationship for the apparent volume of distribution or the steady-state volume of distribution. The percentage of the oral and intravenous dose recovered in urine up to 5 hours after dosing was significantly and inversely correlated with age. The implications of the latter finding are discussed with regard to the interpretation of the xylose tolerance test used to assess gastrointestinal absorptive capacity.