DESENSITIZATION OF PHOBIAS: SOME PSYCHOPHYSIOLOGICAL PROPOSITIONS

This study tested twelve hypotheses derived from psychophysiological theory underlying the systematic desensitization method of reducing phobic anxiety. Subjects with phobias imagined threatening scenes and neutral scenes under relaxed or non-relaxed conditions while cardiac, respiratory, digital vasomotor, and skin conductance activity was recorded. Seven hypotheses were confirmed for one or more response measures. The results indicated that (a) imagining threatening scenes produces autonomic arousal in direct proportion to degree of subjective threat associated with the scenes, (b) autonomic reactions do not extinguish and countercondition faster to weak stimuli than to strong stimuli, and (c) muscle relaxation has a demonstrable but limited effect on counteracting autonomic fear reactions. Desensitization theory was partially supported.     

Effect of tolazoline hydrochloride on sputum viscosity in cystic fibrosis

Comparisons have been made between the effects of autonomic dysfunction and the pathophysiological changes in the exocrine secretions from patients with cystic fibrosis (Roberts, 1959). Cotton (1966) found that administration of tolazoline hydrochloride (an alpha-adrenergic blocker) to patients with cor pulmonale in the terminal stages of cystic fibrosis was associated with an improvement in the results of their lung function tests. This effect might have been due to an alteration of the abnormal viscosity of the bronchial mucus mediated via the autonomic nervous system, thus permitting easier expectoration. Measurement, by means of a Ferranti-Shirely cone and plate viscometer, of several different aspects of sputum viscosity is described. Tolazoline hydrochloride, administered to five patients with cystic fibrosis, was shown not to differ significantly from a placebo in its effect on sputum viscosity and dynamic lung volumes. We could not relate the improved lung function seen in Cotton's series to an autonomic effect of the drug on the physical properties of bronchial mucus in this condition.     

Mineral metabolism and vascular damage in children on dialysis

Cardiovascular disease is increasingly recognized as a life-limiting problem in young patients with chronic kidney disease, but there are few studies in children that describe its determinants. We studied the association of intact parathyroid hormone (iPTH) levels and their management on vascular structure and function in 85 children, ages 5-18 years, who had received dialysis for > or =6 months. Compared to controls, dialysis patients had increased carotid intima-media thickness and pulse-wave velocity. All vascular measures positively correlated with serum phosphorus levels, while carotid intima-media thickness and cardiac calcification score also correlated with iPTH levels. Patients with mean time-integrated iPTH levels less than twice the upper limit of normal (n = 41) had vascular measures that were comparable to age-matched controls, but those with iPTH levels greater than twice the upper limit of normal (n = 44) had greater carotid intima-media thickness, stiffer vessels, and increased cardiac calcification than controls. Patients with increased carotid intima-media thickness had stiffer vessels and a greater prevalence of cardiac calcification. There was a strong dose-dependent correlation between vitamin D and all vascular measures, and calcium intake from phosphate binders weakly correlated with carotid intima-media thickness. In conclusion, both iPTH level and dosage of vitamin D are associated with vascular damage and calcification in children on dialysis.