Shock intensity and the Kamin effect in one- and two-way avoidance.

Describes 2 experiments with 144 and 162 male hooded rats. Response decrements as a function of the intersession interval occurred in both 1- and 2-way active avoidance conditioning. Percentage avoidances were a positive function of shock intensity in 1-way avoidance and a negative function of intensity in 2-way avoidance. The magnitude of the performance decrement was a function of shock intensity in 1-way avoidance, with the largest decrement at the lowest shock intensity. The magnitude of the performance decrement was unaffected by shock intensity in 2-way avoidance. The shape of the intersession-interval function was apparently unaffected by shock intensity in both types of active avoidance. (French summary) (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aplasia of toe phalanges and nails

An infant born without toenails and without the middle and distal phalanges of the toes was otherwise normal, on clinical and radiological examination. This is the second case of this entity to be described. It is speculated that an environmental insult at the critical period of fetal toe development may be the cause of the anomaly, but a genetic factor cannot be excluded.     

A delayed suppression of the renin-aldosterone axis following saline infusion in human hypertension

The purpose of this study was to compare the acute suppressibility of the renin-angiotensin-aldosterone (RAA) axis in normotensive (n = 23) and essential hypertensive (n = 62) subjects. Only those hypertensive subjects with normal plasma renin activity (PRA) levels (sodium restricted, upright) were included in the study. Acute suppression of the RAA axis was determined by measuring PRA, plasma angiotensin II (A II), and plasma aldosterone (PA) at frequent intervals during the infusion of isotonic saline (500 ml/hour for 6 hours). Although all parameters fell significantly from control levels by 20-30 minutes in the normotensive subjects, we found that 60% of the hypertensive subjects showed no significant decline in PRA or PA until 120-240 minutes after beginning the infusion. The other hypertensive subjects showed normal RAA suppression. In addition, while there were no significant differences between the three groups in control PRA or PA levels, we found that the PA levels from 30 to 240 minutes during the saline were significantly higher (P less than 0.01) in the hypertensive subjects with delayed suppression. That there were two distinct populations in the hypertensive group was suggested by the bimodality of the frequency response curve, with peaks occurring at 30 and 240 minutes. These studies indicate an abnormality in the acute suppression of the RAA axis in a substantial proportion of subjects with normal renin essential hypertension. Since previous studies in normal subjects have reported that the early phase of response to saline infusion is related to the sodium ion per se and not to intravascular volume expansion, we have come to the conclusion that the present data are consistent with the hypothesis that the delayed suppression hypertensive group has a diminished ability to respond to the sodium ion.     

Morphologic basis of psychoses associated with vascular and senile pathology

The paper deals with a study of 100 patients diagnosed as combined senile and vascular psychoses. It is marked that in classical cases of such combinations the disorder has 3 stages. On the first stage there is a predominance of vascular pathology. After 60 years of age (the second stage) the senile sumptomatology disguises many symptoms of vascular lesions. The third stage is characterized by a vascular catastrophe. In many cases of combined psychoses there may be complications of other somatic pathology and mainly of lung and liver disorders.     

Multi-input/multioutput system identification using p.r.b.s.

Digital-computer results are presented of a multivariable system identification using p.r.b.s. on a noisy system.     

Development of visual pattern classification in preschool children: Prototypes and distinctive features.

Studied the use of prototypes and distinctive features in visual pattern classification with 12 Ss at each of 3 age levels: 4, 5, and 6 yrs. All Ss attended day-care centers in middle-class neighborhoods of metropolitan Canadian areas. Two tasks were performed: (a) an oddity task requiring selection of the odd pattern in problems containing 2 patterns generated from 1 prototype and 1 from another, and (b) a sequential task requiring designation from memory of each pattern's class membership. There was a marked improvement in oddity task classification accuracy between the 4- and 5-yr age levels. Performance at each age level could be predicted from measures of deviation from prototype and 2 distinctive features unrelated to pattern class membership. In the more difficult sequential task, the preschoolers did not respond to an entire set of features as subsumed in prototype measures, but a single class-defining feature significantly predicted the classifications of the 4- and 5-yr-olds. It is concluded that the ability to use single features develops prior to the ability to use a feature list or prototype and that both distinctive features and prototypes are important for perceptual learning and development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced HBsAb production in pathogenesis of fulminant viral hepatitis type B

The possible importance of humoral immunity in the pathogenesis of fulminant hepatitis was investigated by comparing 17 patients with fulminant hepatitis type B with 20 patients with severe but non-fulminant disease. Hepatitis B surface antigen (HBsAg) was cleared from the serum significantly faster (P less than 0-001) in those with fulminant hepatitis, and in 41% anti-HBsAg (HBsAb) was detectable by radioimmunoassay (RIA) at presentation. In all 11 sera from patients with fulminant hepatitis that were examined by electron microscopy aggregates of HBsAg and HBsAb were seen. In contrast, HBsAb was never detected by RIA in those with non-fulminant hepatitis, and in only one serum specimen (5%) were aggregates seen on electron microscopy. A significant sex difference between fulminant and non-fulminant hepatitis was observed, 65% of patients with fulminant hepatitis but only 15% of patients with non-fulminant hepatitis being women (P less than 0-01). An enhanced production of HBsAb in fulminant hepatitis, by leading to free HBsAb in portal blood, may cause an Arthus reaction in the sinusoids of the liver with ensuing ischaemic necrosis of hepatocytes.