Biomedical subjects
P M Harris
Publications and source records attributed to P M Harris.
Changes in adipose tissue of the rat due to early undernutrition followed by rehabilitation. 1. Body composition and adipose tissue cellularity.
1. Male Black and White Hooded rats were allocated at birth to foster mothers in litters of three, nine or sixteen. At weaning animals from each of these litter sizes were ad lib.-fed on a stock diet forming three ad lib.-fed control groups. At weaning further animals from litters of nine and sixteen were fed on the stock diet in restricted amounts until 12 weeks of age. These undernourished animals were then rehabilitated by being allowed ad lib. access to the stock diet. 2. Five animals from each group were killed at various stages of the experiment, their bodies analysed for fat and nitrogen, and the size and number of cells determined in four specific fat depots. 3. The previously undernourished rats failed to make a complete recovery and were significantly smaller than ad lib.-fed animals from the same litter at 32 weeks of age when the experiment was terminated. 4. The previously undernourished rats from litters of nine deposited a significantly greater porportion of fat in their bodies during rehabilitation than ad lib.-fed animals from litters of nine over the same gain in body-weight. The previously undernourished rats from litters of sixteen deposited the same proportion of fat in their bodies during rehabilitation as ad lib -fed animals from litters of three, nine and sixteen over the same gain in body-weight. 5. There were no significant differences in apparent or total fat cell numbers between ad lib.-fed animals and undernourished-rehabilitated animals at any of the four sites studied at 32 weeks of age.
Changes in adipose tissue of the rat due to early undernutrition followed by rehabilitation. 2. Strain differences and adipose tissue cellularity.
1. Male Wistar rats were allocated at birth to foster mothers in litters of three, nine or sixteen. At weaning animals from each litter size were ad lib.-fed on a stock diet. Further animals from litters of nine and sixteen were fed on the stock diet in restricted amounts until 12 weeks of age and then rehabilitated by being allowed ad lib. access to the stock diet. 2. Five animals from each group were killed at 24 weeks of age and the size and number of cells determined in four specific fat depots. 3, Animals reared in litters of sixteen and further undernourished from 3 to 12 weeks (group L16/U) had significantly fewer fat cells at all sites studied than animals reared in litters of three and ad lib.-fed. Group L16/U animals also had significantly fewer observable fat cells at the epididymal site than ad lib.-fed animals reared in litters of nine. These results differ from those found in the Black and White Hooded rat where, after similar treatments, no significant differences in observable fat cell number were found.
Changes in adipose tissue of the rat due early undernutrition followed by rehabilitation. 3. Changes in cell replication studied with tritiated thymidine.
1. Well-nourished rats were injected with tritiated thymidine at 15, 22, 28 or 84 d of age. At 1, 6, 11 and 16 d after injection animals from each group were killed, samples of adipose tissue were removed from two subcutaneous sites (abdominal and scapular) and separated, using collagenase (EC 3.4.24.3), into 'fat cell' and 'stromal cell' fractions. The specific (radio)activity of DNA isolated from each fraction was measured. The specific activity of DNA isolated from two 'deep body' sites (perirenal and epididymal) was measured only in the animals injected at 84 d of age. 2. Animals undernourished from birth up to 84 d of age were injected with tritiated thymidine at 22, 28 or 84 d of age. Animals were killed 1 and 11 d after injection, adipose tissue removed, and the specific activity of DNA measured. Other undernourished animals were rehabilitated from 84 to 107 d and injected at 91 d of age with tritiated thymidine. The animals were killed 1, 6, 11 and 16 d after injection, adipose tissue was removed from the subcutaneous and deep body sites and the specific activity of DNA determined as before. 3. In well-nourished animals fat cell replication had largely ceased by 12 weeks of age in the subcutaneous depots. There were differences between the various sites of adipose tissue regarding the period of hyperplastic growth, its timing or rate of replication or both. 4. In undernourished animals replication was slow in the subcutaneous depots compared with well-nourished animals of the same age. Rehabilitation from undernutrition stimulated replication which resulted in higher rates in all four depots examined compared with those in well-nourished animals. 5. The findings are discussed in relation to the concept of a finite period of hyperplasia for adipose tissue.
Deposition of fat in the body of the rat during rehabilitation after early undernutrition.
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Ethionine administration in the rat. 2. Effects on the incorporation of [P]orthophosphate and dl-[1-C]leucine into the phosphatides and proteins of liver and plasma.
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