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Biomedical subjects

J Hirsch

Publications and source records attributed to J Hirsch.

At least 343 records · Page 19Linked to original sources
PubMed1971

Cellularity of adipose depots in the genetically obese Zucker rat.

Cell size and number of three adipose depots, epididymal, retroperitoneal, and subcutaneous, were determined during growth of the obese Zucker rat ("fatty") and nonobese Zucker control. Cellularity of these depots in the adult "fatty" was compared with that in nonobese controls and in nonobese Zucker rats made obese by ventromedial hypothalamic lesions. Epididymal and retroperitoneal depots in the nonobese rat grew by cell enlargement and increase in cell number until the 14th wk, when number became fixed; further increase in depot size occurred by cell enlargement. The subcutaneous depot added cells until the 26th wk. In the Zucker "fatty," cell number increased until the 26th wk in all depots, accompanied by extreme cell enlargement. The enlarged adipose depots of the adult Zucker "fatty," when compared with the nonobese control, are the result of both hypertrophy and hyperplasia. Depot enlargement in the lesioned animal is the result of hypertrophy. "Fatties" have more cells in adipose depots than do lesioned rats. Genetic obesity in the Zucker rat is clearly different from the obesity produced by hypothalamic lesioning.

Adipose Tissue↗
PubMed1969

Cellularity of rat adipose tissue: effects of growth, starvation, and obesity.

The size, number, and rate of formation of mature adipocytes were studied in the epididymal pads and retroperitoneal adipose depots of the Sprague-Dawley rat. Early growth of these depots was accompanied by progressive enlargement of adipose cells as well as by increases in number. Beyond the 15th wk of life, the depot grew exclusively by the process of cellular enlargement, with no further change in cell number. Severe starvation during the 6th wk of life followed by normal feeding had no lasting effect on cell size or cell number; prolonged semistarvation beginning in the 15th wk greatly reduced cell size while cell number was unaffected. Likewise, extreme increases in depot size produced by hypothalamic lesions did not change cell number, but only cell size. The concept of a fixed number of mature adipocytes in the adult organism may be of central importance in caloric and metabolic equilibrium.

Adipose Tissue↗
PubMed1968

The role of adipose cell size and adipose tissue insulin sensitivity in the carbohydrate intolerance of human obesity.

Glucose metabolism and insulin sensitivity of isolated human adipose tissue was studied as a function of adipose cell size and number. Glucose metabolism by these tissues was closely related to the number of cells in the fragment, irrespective of cell size. Adipose cells of obese individuals metabolized glucose to carbon dioxide and triglyceride at rates similar to adipose cells of nonobese subjects. In contrast, insulin responsiveness of adipose tissue was dependent upon adipose cell size. The larger its adipose cells the less insulin sensitive was the tissue. Thus, adipose tissue of obese subjects, with enlarged cells, showed a diminished response to insulin. After weight loss and reduction in adipose cell size, insulin sensitivity of the adipose tissue of obese patients was restored to normal. When adipose tissue of obese individuals showed impaired responsiveness to insulin, their plasma insulin levels, after oral glucose, were elevated. Weight loss and reduction in adipose cell size restored plasma insulin concentration to normal, concomitant with the return of normal tissue insulin sensitivity.

Journal Article↗
PubMed1968

Effect of early nutrition on the development of rat epididymal fat pads: cellularity and metabolism.

The effect of infantile nutritional levels on adipose tissue cellularity and metabolism was studied in two groups of Sprague-Dawley rats. Caloric intake was varied during the suckling period by manipulating litter size immediately after birth; however, all animals had free access to food after weaning. The epididymal fat pads of animals raised in small litters were heavier than those of their paired siblings raised in large litters. Initially, the differences in pad weight were accounted for primarily by differences in total cell number; however, at 20 wk both cell number and cell size contributed equally. The rate of glucose incorporation into CO(2) and triglyceride during in vitro incubations was the same for both groups if expressed on a per cell basis; therefore total tissue incorporation was greater in animals with more cells. The results support the hypothesis that early nutritional experiences can effect permanent changes in the cell number and size of the epididymal fat depot and that total cell number is important in the total metabolism of this organ. These findings and the fact that extreme human obesity is accompanied by similar alterations in cellularity and metabolism indicate that early nutritional experiences should be studied further as a guide to the etiology of obesity in man.

Adipose Tissue↗
PubMed1968

Methods for the determination of adipose cell size in man and animals.

Four methods for the sizing of adipose cells in small samples of human or animal adipose tissue are compared. These methods depend on the preparation of cell suspensions by incubation of the tissue with collagenase or by prolonged fixation with osmium tetroxide and separation of the fixed cells. A Coulter electronic counter was used to count and size the suspended cells and a Zeiss particle size analyzer for the sizing of cells in photomicrographs. The use of the Coulter counter to count cells in a suspension derived from a known amount of tissue and subjected to osmium tetroxide fixation is recommended for accuracy and general applicability to adipose cells of all sizes in man and animals.

Adipose Tissue↗