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Biomedical subjects

J L Smart

Publications and source records attributed to J L Smart.

At least 91 records · Page 5Linked to original sources
PubMed1977

Problems of undernutrition research with breeding mice.

Rats undernourished throughout pregnancy and lactation lose few young during the suckling period and wean normal size litters of extremely growth-retarded offspring. Comparable treatment of maternal mice, on the other hand, resulted in considerable nestling mortality. Thus few young were reared to weaning and these were not nearly as growth-retarded. Detailed evidence is given of the effects of different schedules of undernutrition throughout pregnancy and lactation on the reproductive performance of mice. These findings are compared with those for rats and possible reasons for the difference in nestling mortality discussed.

Animal Nutritional Physiological Phenomena↗
PubMed1976

Suspected botulism in foxhounds.

An outbreak of acute paralysis in a pack of foxhounds, which followed the ingestion of raw and partially cooked meat, was almost certainly due to botulism. Botulinal toxin was detected in the serum of one of three hounds which recovered, and Clostridium botulinum type C was present in a sample of meat remaining from a batch fed to the hounds.

Animal Feed↗
PubMed1976

Undernutrition in early life: lasting effects on activity and social behavior of male and female rats.

The growth-retarded offspring of mother rats undernourished throughout pregnancy and lactation were fed ad libitum from weaning. Males were tested at 100 days of age, and ovariectomized females at 150 days. After 2 weeks of isolation, pairs of males consisting of 1 control (C) and 1 previously undernourished (PU) rat were observed for 10 min on each of 9 consecutive days. Similarly paired and treated female rats were tested a total of 8 times, the first 3 tests being separated from the last 5 by a 10-day interval. The PU rats, whether male or female, performed more rearing responses and PU male rats ambulated more in the social situation than C rats. The PU males also performed more of the social responses allogroom, walk over, and mount than C males. Similarly, PU females performed more allogroom and crawl under than C females. In general, PU rats were more active than C rats and more socially responsive.

Age Factors↗
PubMed1976

Nutritionally small-for-dates rats: their subsequent growth, regional brain 5-hydroxytryptamine turnover, and behavior.

Rats were subjected to nutritional growth retardation either from conception to 5 postnatal days of age (fetal and neonatal restriction (FNR) group), or from 5 to 25 postnatal days of age (infantile restriction (IR) group). The FNR group may serve as a model for the human small-for-dates baby. At 20 weeks of age cerebellum, midbrain, and cerebrum were significantly reduced in weight by 4%, 5%, and 4%, respectively, in FNR animals when compared with controls. Only cerebellum and midbrain were affected in IR rats of the same age, but in both regions the percentage deficits (8% and 9%, respectively) were greater than in FNR animals. Both cerebellum and midbrain weighed significantly less in IR than in FNR rats. The timing of nutritional growth retardation appeared to be of little consequence to the regional brain turnover of 5-hydroxytryptamine in adulthood. The rate of synthesis in the hippocampus of both FNR and IR animals was significantly faster (67% and 75% respectively) than in controls. The increased turnover could perhaps represent "overactivity" of those 5-hydroxytryptaminergic neurons terminating in the hippocampus. Some differences in the behavior of the previously undernourished adult animals were also evident. On the fifth day of testing, control rats were most venturesome in the open field. Eighteen control rats left the edge zone within 2 min, whereas only 8 FNR and 11 IR rats did so. Most animals froze immediately after a 7-sex exposure to a loud electric bell. The delay before moving about again differentiated the three groups. FNR rats took longest to move out of the area in which they froze.

Age Factors↗
PubMed1975

Motor co-ordination and cerebellar size in adult rats undernourished in early life.

The male progeny of mother rats which had been undernourished during most of gestation and all of lactation were divided into two groups when weaned at 25 days. One group was nutritionally rehabilitated (G-L-) while the other was underfed for a further 9 weeks (G-L-W-) before nutritional rehabilitation. Despite this further undernutrition the G-L-W- rats eventually caught up in both body and brain weight with the G-L- group. Compared with control rats of the same age that had been well fed throughout life, the G-L- and G-L-W- animals had permanent deficits in body and regional brain weights. At 36 weeks rats were given two tests of motor co-ordination. They were required (a) to run backwards on a revolving drum and (b) to cross a chasm bridged by a ladder or parallel rods for a food reward. Both previously undernourished groups did consistently worse than controls of the same age or of similar body weight on two measures of co-ordination: falls from the revolving drum and stumbles on the bridge-crossing test. It is postulated that these differences indicate impaired cerebellar function in the prevously undernourished rats.

Age Factors↗
PubMed1975

Thresholds of response to electric shock in previously undernourished rats.

1. Rats were undernourished in early life by feeding their mothers a restricted quantity of a good-quality diet during pregnancy and lactation. All offspring were fed ad lib. from weaning. Behavioural tests were done using adult males. 2. Thresholds of aversion to electric shock were determined in a rectangular box, one side of which was designated 'live' and the other 'safe' (o V side) for any particular shock level. Three 15 min sessions were given at each of five shock levels. Previously undernourished rats had a lower aversion threshold than controls. They spent more time than controls on the o V side at two intermediate levels of shock. 3. Other male rats were subjected to six graded series of brief, unavoidable shocks. Previously undernourished rats responded to a greater total number of shock than controls. 4. These results support the hypothesis that previously undernourished rats have a lowered threshold of arousal.

Animal Nutritional Physiological Phenomena↗