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J M Leatherwood

Publications and source records attributed to J M Leatherwood.

At least 19 recordsLinked to original sources
PubMed1986

Insulin responsiveness of diaphragm tissue and adipose cellularity in mice selected for rapid growth.

Four lines of mice, two lines selected for rapid growth (large body weights) (M16 and H6) and their unselected control lines (ICR and C2, respectively), were examined for traits related to obesity. The M16 line is obese while the other three lines are normal in body composition at 10 weeks of age when fed stock diet. In experiment I, mice were fed stock diet and examined at intervals from 4 to 22 weeks of age. Mice were fed either a high-carbohydrate or high-fat diet in experiment II and examined at 4, 6 and 10 weeks of age. The traits measured were serum glucose, serum insulin and in vitro insulin responsiveness of diaphragm muscle. Epididymal adipose cellularity was determined at 10 weeks of age. Insulin responsiveness was determined for the diaphragm muscle by 2-deoxyglucose uptake. Body weights differed significantly (M16 greater than H6 greater than ICR greater than C2, P less than 0.01). The M16 obese line was hyperglycemic and mildly hyperinsulinemic while the H6 line was hypoglycemic and normoinsulinemic. Basal 2-deoxyglucose uptakes by diaphragm muscle were similar among lines while the insulin-stimulated uptake by M16 and H6 lines was less (P less than 0.01) than the stimulated uptake by their control lines. Diet did not affect basal uptakes, but high-fat diets reduced (P less than 0.01) the insulin stimulated uptakes when compared to the high-carbohydrate diet. Selected lines had more and larger epididymal adipocytes than control lines when fed the stock diet (P less than 0.01). Decreased insulin responsiveness of muscle tissue among the lines occurred concomitantly with an increase in adipocyte size.

Adipose Tissue↗
PubMed1984

Relationship of brown adipose tissue with growth and obesity differences in genetically selected mouse lines.

A recent hypothesis considers brown adipose tissue (BAT) to be an important source of diet-induced thermogenesis (DIT). In turn, DIT and thermogenesis in general are believed to be key factors in the control of obesity of laboratory rodents. This hypothesis was developed from the study of single gene mutant obese rodents. The present research tested this hypothesis in mice with polygenic control of growth and obesity, which is more characteristic of the type of genetic variation expected in human and other mammalian populations. Control and high fat diets were used to test responses of five genetically selected lines of mice showing different patterns of growth and obesity. All lines deposited more fat on the high fat diet, but the most obese line showed the largest increase in BAT and the lipid-free dry (LFD) component of BAT. Use of LFD per unit body weight gave results which supported the hypothesis being tested, but it was argued that this measure is misleading. When brown and white adipose tissue growth relative to body weight were examined, 2 of the 10 line-diet groups showed alterations in BAT growth patterns. However, it was concluded that BAT, if involved at all, was not a major factor in growth and obesity differences.

Adipose Tissue, Brown↗
PubMed1984

Effects of feeding pattern and dietary regimen on growth and adipose tissue cellularity in polygenic obese mice.

The effect of varying feed intake and feeding pattern during the early postweaning period on growth, body composition and adipose tissue cellularity was studied in polygenic obese and control normal mice. Male mice were assigned to the following dietary treatments at 4.5 wk of age: stock diet fed ad libitum(AL), four palatable foods cafeteria-fed(CF), stock diet fed every 2 h by automatic feeders adjusted for maximum intake(MI), fed same procedure as MI but restricted to produce 70% of the gain of mice fed ad libitum(RE), and stock diet fed one meal/d the same amount fed RE mice(PM). Mice were killed after 5 wk on treatment. Cafeteria-fed control mice were heavier (P less than .05) than RE control mice, but they were not different (P greater than .05) from AL, MI and PM control mice, while CF obese mice were heavier and RE obese mice were smaller than AL, MI and PM obese mice (P less than .05). Cafeteria-fed mice were fatter than mice from all other treatments in both the obese and control lines. Maximum intake, PM and RE mice were fatter than AL mice but this effect was only significant in the obese line. Alterations in feeding pattern can affect body composition even though body weight may not show a correlated response. Cafeteria-fed obese mice had larger fat pads and more small (less than 40 micron) and large (greater than 110 micron) adipocytes than other obese mice. Results indicate that the difference in the development of obesity on cafeteria diet was due primarily to genetic effects while the increase in percentage fat after restriction on MI, PM and RE treatments was due mainly to the acute change of feeding pattern.

Adipose Tissue↗
PubMed1983

Effects of preweaning and postweaning feed restriction on the development of polygenic obese mice.

Polygenic obese (M16) and control (ICR) mice were raised in litters of 8 (N8) or preweaning restricted in litters of 14 (N14). Mice were fed either ad libitum or postweaning restricted by automatic feeders from 4 to 10 weeks of age. All mice were fed ad libitum from 10 to 16 weeks. Preweaning restriction (N14) resulted in mice at 4 weeks with smaller body weights, fat percent, subcutaneous fat depot and adipocyte diameter than N8 mice. Most of the effects of preweaning restriction were overcome by 10 weeks. Obese mice, at 10 and 16 weeks, were heavier and had higher fat percent and larger fat depots with more and larger adipocytes than control mice. Postweaning restriction resulted in mice at 10 weeks with smaller body weight but greater fat percent, especially in the control line. Postweaning restriction of obese mice resulted in a higher percent of fat at 16 weeks. The change in eating pattern, stress or other factors associated with postweaning restriction, as imposed in this study, resulted in an altered metabolism that distributed a greater proportion of energy to fat storage than in the ad libitum fed mice. Ultimate body size and adipose tissue characteristics were determined primarily by genotype, whereas most effects of nutritional restriction were temporary.

Adipose Tissue↗
PubMed1982

Additive, nonadditive and maternal genetic effects on adiposity in mice fed different levels of fat.

Polygenic obese (M16), nonobese (ICR) and reciprocal crossbred (M16 male x ICR female and ICR male x M16 female) mice were fed ad libitum diets containing 1, 5 or 25% fat from 3 to 10 weeks of age. Epididymal and subcutaneous fat depot weights (E, S) and depot weights as a proportion of empty body weight (E%, S%) were used as measures of adiposity at 6 and 10 weeks of age. Genetic differences in adiposity among the four populations were partitioned into average direct (a), average maternal (m) and direct heterotic (h) effects. Line M16 was greater than ICR at both 6 and 10 weeks in E (81% at 6 weeks and 114% at 10 weeks), S (82%, 73%), E% (27%, 37%) and S% (26%, 12%). Average direct genetic effects, as determined by a, accounted for 60% of the M16 vs. ICR line difference in E and S at six weeks, the remainder of the difference being due to m. The major portion of the line difference in E% and S% at 6 weeks was accounted for by m. At ten weeks of age, most of the line difference in E, S, E% and S% was due to additive direct genetic effects while the contribution of maternal genetic effects was negligible. Heterosis was sizeable for all measures of adiposity, varying from 10.8% in S% at 10 weeks to 26.8% in E at six weeks, possibly indicating the presence of directional dominance. E and E% increased significantly with the increase in dietary fat percent, but S and S% were not affected. Interactions of genotype with level of dietary fat percent were not significant for the epididymal or subcutaneous fat depot weights or proportional weights.

Aging↗
PubMed1981

Adipose cellularity, serum glucose, insulin and cholesterol in polygenic obese mice fed high-fat or high-carbohydrate diets.

Polygenic obese (M16) and nonobese (ICR) mice were fed ad libitum either a high-fat (FAT) or high-carbohydrate (CHO) diet from 6 to 10 weeks of age. After this four-week period, M16 exceeded (P less than 0.01) ICR mice and FAT-fed exceeded (P less than 0.01) CHO-fed mice in body energy percent, body fat percent, and weight and proportional weight of epididymal and subcutaneous fat pads. Fat cell size and number in both fat depots were greater (P less than 0.01) in the M16 than in the ICR line. Mice fed FAT had larger (P less than 0.01) fat cells in both depots compared with CHO-fed mice, but fat cell nuber was not altered significantly. M16 mice were hyperglycemic, hyperinsulinemic and hypercholesterolemic, Dietary treatment did not affect glucose or insulin levels, but cholesterol was greater (P less than 0.01) on FAT than on CHO diet. Lipoprotein lipase and fatty acid synthetase activities were greater in M16 than in ICR mice, while fatty acid synthetase activity was greater in mice fed CHO than in those fed FAT. Genotype by diet interactions were not important for the traits studied. Polygenic obese mice, developed by selection for increased growth rate, share many of the characteristics of the single gene obesity syndromes in rodents. The development of obesity in polygenic obese mice may be due, in part, to an acceleration of the normal developmental process of growth, in addition to hyperphagia and increased energetic efficiency.

Adipose Tissue↗
PubMed1981

Predicting percent fat in mice.

Body energy/body weight (ENGY), percent water (WAT%) and proportional weight of the epididymal fat pad (FPAD%) were used as independent variables to predict fat percent (FAT%) in three independent studies with mice. Prediction equations were found to be valid based on the following criteria: 1) high correlations between observed FAT% and predicted fat percent based on prediction equations derived from an independent data set and 2) negligible correlations between predicted fat and FAT% minus predicted fat. Although any two of the independent variable generally provided a better fit than one variable, use of one of the three independent variables is probably sufficient for most applications. Based on the coefficient of determination, ENGY was the best single predictor of FAT% followed by WAT% and FPAD%. However, FPAD% may be most useful in large experiments where a rapid procedure is essential.

Adipose Tissue↗
PubMed1980

Thyroid hormones and efficiency of energy utilization in mice selected for body weight.

Plasma thyroid hormones and energetic efficiency were examined in selected lines of mice during the fifth, sixth and seventh weeks of age. Mice from an unselected control line (C2) and from lines selected for large (H6) or small (L6) 6-week body weight were fed either ad libitum or restricted to approximately 75% of ad libitum intake. The H6 line was more efficient in energy deposition than the C2 and L6 lines with regression coefficients of change in body energy (kcal/kg0.75) on metabolizable energy (ME) intake (kcal/kg0.75) of 0.46+/-0.04, 0.26+/-0.03 and 0.26+/-0.03, respectively. Double-antibody radioimmunoassays for triiodothyronine (T3) and thyroxine (T4) were validated for unextracted mouse plasma. Plasma T4 concentration was greater (P less than 0.01) in the H6 line than in L6 and C2 lines, with the means of ad libitum mice being 36.7+/-1.6, 26.3+/-1.2 and 24.5+/-1.5 ng/ml, respectively. Plasma T3 concentration did not differ between lines but decreased (P less than 0.01) at 7 weeks of age. Feed restriction decreased (P less than 0.05) T4 concentration from 29.2+/-0.8 to 26.7+/-0.8 ng/ml and decreased (Pless than 0.01) T3 concentration from 1.93+/-0.02 to 1.82+/-0.02 ng/ml. Selection for 6-week body weight altered the efficiency of energy deposition and the thyroid hormone plasma concentration.

Aging↗
PubMed1980

Use of a cellulase-derepressed mutant of cellulomonas in the production of a single-cell protein product from cellulose.

A cellulase-derepressed mutant of a Cellulomonas species was used to produce single-cell protein from crystalline cellulose. In preliminary tests, maximum yield of single-cell protein was obtained at 30 degrees C (pH 7.0) with urea as the nitrogen source. A continuous-flow foam flotation procedure was developed for rapid and efficient separation of bacteria from the culture liquid and cellulose residue. A pH of 4.5 was optimum for foam flotation of this organism. In preliminary trials, recovery was 85% of the cells with the flotation procedure. Cellulomonas was 68% true protein and had an essential amino acid profile featuring a high lysine content (6.5% of protein). The Cellulomonas product was evaluated nutritionally with weanling rats. The net protein utilization value for the protein supplemented with methionine was 50.4% Weight gain of rats on the Cellulomonas diet was similar to that of rats fed a casein diet.

Journal Article↗
PubMed1978

Adipose cellularity and body composition in polygenic obese mice as influenced by preweaning nutrition.

Male mice from a line selected for rapid postweaning growth (M16) and an unselected control (ICR) were reared from birth to 3 weeks either in litters of eight (N8) or 14 (N14). Body weight gain and feed intake of M16 mice were greater than ICR. These high rates of gain and feed intake also were extended to an older age in M16 (10 weeks) than in ICR (6 weeks). The M16 line exceeded the ICR line and N8 mice exceeded N14 for fat, lean, ash, and live body weights at 4, 6, 10, 16, and 30 weeks of age. Fat percentage was greater in N8 than N14 for both ICR and M16. The adipose cellularity of the epididymal fat pads of M16 indicated a hypertrophic-hyperplastic form of obesity at 10, 16, and 30 weeks. Within each line, the N14 mice had fewer and slightly smaller fat cells than N8. However, M16-N14 mice still had considerably more and larger fat cells than ICR-N8. Restriction of energy intake from birth to 3 weeks reduced subsequent feed intake and degree of obesity. After 4 weeks, the genetic effect exerted a greater influence on the development of obesity than the preweaning nutritional regimen.

Adipose Tissue↗
PubMed1978

Effect of postweaning feed restriction on adipose cellularity and body compositon in polygenic obese mice.

The M16 line of mice, selected for rapid postweaning gain, exhibits polygenically controlled obesity and hyperphagia. The effect of limiting postweaning energy intake on the subsequent growth and development of obesity in M16 mice was investigated. Male mice from M16 and an unselected line (ICR) were provided either ad libitum or limited (congruent to 70% of ad libitum) feed during the rapid postweaning growth period from 4 to 6 weeks of age. Body weights (g) at 6 weeks of age were: ad libitum ICR (31.0 +/- 0.6), restricted ICR (23.8 +/- 0.7), ad libitum M16 (45.0 +/- 0.6) and restricted M16 (30.1 +/- 0.6). In both lines, restricted feed intake severely depressed body fat, lean, ash, and water at 6 weeks. In addition, percent triacylglycerol, fat cell size and number in the epididymal fat pads were lower. Restricted M16 and ICR mice showed a marked compensatory gain in all body components when subsequently fed ad libitum for 10 weeks. All measurements of adiposity at 16 weeks were similar for the restricted and ad libitum regimens within each line. The relative amounts of energy deposited as fat and lean between 4 and 16 weeks were not influenced by restricted feeding, but M16 mice deposited a larger proportion of energy as fat than as lean when compared with ICR mice. The results suggest that fat cell number is determined at a relatively early age in mice and is primarily under genetic control.

Adipose Tissue↗
PubMed1976

Derepressed synthesis of cellulase by Cellulomonas.

A Cellulomonas sp. was isolated from the soil which hydrolyzed cellulose, as shown by clear-zone formation on cellulose agar medium. Catabolite repression of cellulase synthesis occurred when moderate levels of glucose were added to the medium. A stable mutant that no longer exhibits catabolite repression was produced through treatment of the wild-type organism with N-methyl-N'-nitro-N-nitrosoguanidine. Both enzyme concentration and specific activity, as determined by the rate of hydrolysis of carboxymethylcellulose, were greater with the mutant than with the wild-type organism under various test conditions. The wild type had no measurable cellulase activity when grown in the presence of either 1.0% glucose or cellobiose. Cellobiose, but not glucose, inhibited enzyme activity towards both cellulose and carboxymethylcellulose. Cellobiose, cellulose, and sophorose at low concentrations induced cellulase synthesis in both the wild-type and the mutant organism. Cellulase regulation appears to depend upon a complex relationship involving catabolite repression, inhibition, and induction.

Actinomycetales↗
PubMed1972

Novel anaerobic cellulolytic bacterium.

A morphologically novel bacterium which ferments cellulose and produces butyric acid was isolated from a bovine rumen. It grows in long twisted chains that often form a double-helical pattern.

Anaerobiosis↗