Some epidemiological aspects of pyloric stenosis in British Columbia

The records of an ongoing Health Surveillance Registry that utilizes multiple sources of ascertainment were used to study the incidence rate of infantile hypertrophic pyloric stenosis (IHPS) in liveborn children in British Columbia during the period 1966–1977 inclusive. The incidence was 4.6 males/1,000 livebirths and 1.2 females/1,000 livebirths, giving a male to female ratio of 3.1 to 1. No significant overall incidence variations with time could be shown during the study period. There was suggestive evidence of independent sex-incidence variation in different geographical regions, which clearly warrants further investigation.     

Electrodermal Lability and Visual Information Processing

Individual differences in electrodermal lability have been related to performance in vigilance and reaction time tasks. The goal of the present study was to employ an "additive factors" approach to identify the stages of information processing that might underlie these effects. Nineteen labile and 17 stabile subjects performed a choice reaction time task in which a visual imperative stimulus was presented under two conditions of intensity (presumed to affect the speed of pre-processing operations) X three conditions of degradation (which influences later encoding processes related to feature extraction). Measures of both reaction time and movement time were obtained. The major findings were: (a) labile subjects had faster reaction times than stabiles, and (b) lability interacted significantly with stimulus degradation. Labiles also tended (p less than .10) to have faster movement times. This pattern indicates that labiles and stabiles differ in the performance of later encoding operations, and possibly in the speed of motor processes as well. However, they do not appear to differ in the early pre-processing of the simple physical attributes of a stimulus.     

Strain differences in mice in the development of tolerance to the anti-pentylenetetrazole effects of diazepam

The development of tolerance to the protective effects of diazepam (4 mg/kg) against seizures induced by pentylenetetrazole (PTZ) were studied in 3 strains of mice. Significant tolerance developed to protection against myoclonic jerks induced by PTZ (90-100 mg/kg) by day 5 in Tuck No. 1 and by day 10 in C3H/HE and CD-1 mice. Tolerance developed to protection against tonic-clonic convulsions by day 10 in Tuck No. 1 mice and by day 30 in the other strains. Diazepam remained protective against tonic-clonic convulsions (but not against myoclonus) induced by threshold doses of PTZ for 30 days in all 3 strains.     

Study of herpes simplex virus type 1 populations obtained from recurrences and primary infections

The analysis of 23 clinical isolates of herpes simplex virus type 1 (HSV-1) showed that 15 of 15 isolates that had undergone a few passages in tissue culture (fresh isolates) and two of eight isolates that had never been passaged (new isolates) were composed of a mixed population with respect to plaque morphology in Vero cells. Cloning and characterization of 10 large plaque viruses (L variants) and nine small plaque viruses (S variants), obtained from seven different isolates, showed the following. BamHI DNA restriction patterns of the L and the S variants from a single isolate differed only with respect to the electrophoretic mobility of the fragments that contain reiteration of specific sequences; they did not differ regarding the presence or the absence of restriction endonuclease cleavage sites. The L and S variants differed with respect to the electrophoretic profiles of infected cell glycoproteins, thermosensitivity of growth and plaquing efficiency at 39 degrees C, and, at least in the case of the two couples of variants that we tested, pathogenicity for the mouse. The hypothesis that the L variants might arise from the S variant during in vivo replication is discussed.     

Effect of treadmill exercise on food intake and body weight in lean and obese rats

Body weight and food intake of lean and obese, male and female Osborne-Mendel rats following treadmill exercise were compared. Rats were assigned, separately by sex, to one of three diet groups; Group 1 was fed a low fat (10%) diet throughout the study, Group 2 was fed a high fat (55%) diet for 16 weeks and then switched to the low fat diet 1 week prior to exercise, and Group 3 was fed the high fat diet throughout the study. To control for differences in work output between the leanest and heaviest animals, exercise intensity was adjusted across groups such that all exercised rats had equivalent energy expenditure. After a 3 day training period, the exercise was successively increased over 8 days until a work output of 374.9J was reached. Relative to their respective controls, obese exercised males showed a reduction in body weight but no change in food intake. In contrast, exercised females showed no change in body weight or food intake, regardless of dietary condition.     

An Association Between a Microsatellite Polymorphism at the DRD5 Gene and the Liability to Substance Abuse: Pilot Study

We have conducted a population-based association study of substance abuse and a microsatellite at the dopamine D5 receptor locus (DRD5) in a sample of European–American males and females with substance dependence (SA) or without any psychiatric disorder. Overrepresentation of the most frequent allele (148 bp) was found in males in the SA group (OR = 2.2, P= .02); this finding was reproduced in females (OR = 5.4, p< .001). The difference in the frequencies of this allele between SA males and SA females was statistically significant. The genotype coded in accordance with the dose of this allele correlated with substance abuse liability in males and females (stronger in females) and with novelty seeking in females. There was no evidence of correlation between the genotypes of spouses that could be induced by assortative mating for the liability to substance abuse. The data suggest that the DRD5 locus is involved in the variation and sex dimorphism of substance abuse liability.CEDAR is a consortium between St. Francis Medical Center and the University of Pittsburgh.     

The effects of age and strain on aggression in male rats

Aggressive behaviors were compared for male Fischer-344 and Long-Evans rats formed into mixed-sex colonies at 100, 200, or 300 days of age. Within each strain, male aggression did not differ across these ages, nor did it differ for an additional group of 600-day old Long-Evans males: both the form and the incidence of specific aggressive and defensive behaviors remained relatively constant over an age range representing nearly the entire normal life span for this species. However, Fischer-344 males at all ages were reliably lower in aggression than the Long-Evans rats. The specific aggression components seen in the Fischer-344 rats tended to be nondamaging, resembling “play fighting” more than the tissue damaging attack behaviors typical of other strains. Despite the frequent use of this strain in gerontological research, such low levels of aggressiveness counterindicate their use in research in aging and aggression.     

Regeneration and growth of the liver in 3-week-old mice of different strains

At the age of 3 weeks, C57BL mice have comparatively low proliferative activity of their hepatocytes when the liver grows normally, but also during regeneration of the liver 44 h after its extensive resection (mitotic index 16%). Animals of the same age but of other strains (noninbred, CBA, and CC57BR), however, in most cases have a higher mitotic index of their hepatocytes both under normal conditions and during regeneration of the liver (42, 70, and 60%). This pattern of interlinear differences in mitotic activity of the hepatocytes during growth and regeneration of the liver was still found 7 days after the beginning of the experiment. The results indicate genetic determination of the level of proliferative activity of cells.Laboratory of Growth and Development, Institute of Human Morphology, Academy of Medical Sciences of the USSR. (Presented by Academician of the Academy of Medical Sciences of the USSR, A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 4, pp. 475–477, April, 1976.     

Length-dependent activation and sensitivity in arterial ring segments

This study examines the effect of length on the dose-response (D-R) relationship and the effect of agonist concentration on the length-tension (L-T) relationship in vascular smooth muscle. The experiments used 2-mm rings from isolated segments of the dog anterior tibial artery. In D-R experiments the length (internal ring circumference) for maximum active force (L_max) was determined first. D-R relationships were obtained from cumulative responses to increasing concentrations of norepinephrine (NE) or potassium (K⁺). L-T relationships were obtained from individual responses to a specific concentration of agonist as the ring was stretched in increments of L₀ (the initial length for resting force). Dimensions of the arterial rings were measured with a video caliper. For NE and K⁺ stimulations at lengths equal to and less than L_max: (a) The concentration for half maximal response (ED₅₀) was lowest (most sensitive) at L_max and increased significantly as length decreased from L_max; (b) When the direction of length change was reversed, the direction of change in ED₅₀ was reversed; and (c) The ED₅₀ of repeated dose-response experiments at L_max was not significantly different. For NE: (a) the ED₅₀ decreased significantly when length was increased from L_max; and (b) the ED₅₀ increased significantly when length was decreased to L_max. The results of L-T experiments show L_max is significantly longer for a low concentration of NE (10⁻⁶ M) than for a high concentration (10⁻⁵ M). With force normalized to the maximum force, the L-T curve is significantly lower, and the initial length for an active response was 80% longer for 10⁻⁶ M than for 10⁻⁵ M NE. It may be concluded that vascular smooth muscle has a length-dependent dose-response relationship and a concentration-dependent length-tension relationship.     

Laterality of Body Focus and Digital Skin Temperature in Patients with Raynaud''s Disease

The purpose of the present study was to assess the relationship between lateralization of body image and right versus left vasomotor activity. Fifteen right-handed female patients suffering from idiopathic Raynaud's disease demonstrated a relationship between the extent of right lateralization of body image and bilateral digital skin temperature during a controlled temperature stress test. In addition, subjects showing a reliable right side awareness demonstrated more unilateral vasospastic attacks in their right hand than their left hand white subjects showing no clear right lateralization by body image reported more left hand attacks than right hand attacks. These results were taken as consistent with previous work on the relationship between skin conductance and lateralization of body image.