Journal - Science

Abstract :

Microsomal particles prepared from isolated rat adipose cellstake up D-glucose more rapidly than L-glucose. The rate of D-glucoseuptake, but not that of L-glucose, is stimulated by incubationof the intact cells with insulin at concentrations as low as10 microunits per milliliter before disruption and preparationof the microsomes.

Abstract :

This project involves the measurement of prostaglandins and phospholipids in adipose tissue and liver, with a special regard to the interrelationship of these compounds in lipolysis and antilipolysis. Studies are progress, studying the relationship of the levels of the prostaglandin E series (measured by thin-layer chromatography and radioimmunoassay) and the different classes of phospholipids (measured by thin-layer chromatography) in situations within the cells of increased and decreased cyclic AMP levels. Levels of cyclic AMP are increased by exposing the isolated cells to epinephrine or norepinephrine, and cyclic AMP levels are lowered by the use of the hormone, insulin. It is hoped by these maneuvers to better understand the role and interrelationship of these compounds to this metabolic process. In addition, it is hoped that a better understanding of the physiology of these compounds will also be forthcoming.

Abstract :

A plasma membrane preparation has been prepared from rat adipose tissue which has many of the features of the glucose transport system in intact cells. Plasma membranes isolated from cells exposed to insulin show an augmented D-glucose uptake as compared to membranes prepared from control adipocytes. Treatment of intact cells with anti-insulin serum (AIS) prior to cell rupture negated the stimulatory effect of insulin observed in the membranes, while treatment of subsequently isolated, insulin stimulated membranes with AIS did not lessen the observed stimulation of D-glucose transport. A number of spectroscopic techniques were used to assess the structure of the insulin-stimulated plasma membranes as compared to membranes from control adipocytes. By these techniques, no differences were observable between insulin stimulated and control membranes. It was of interest to see if the observed change in the plasma membrane glucose transport function might be due to the formation of a phosphoprotein. 32Pi was incubated with intact adipocytes to steady state 32P incorporation into protein (2 hours), and the cells were then ruptured and fractionated into the major subcellular fractions. The peptides in these fractions were separated on polyacrylamide gels containing sodium dodecylsulfate. 32P-phosphopeptides were assessed by quantitative radioautography. If the intact cells were exposed to epinephrine prior to rupture the phosphorylation of a large number of peptides, located in the cytosol, endoplasmic reticulum and plasma membrane was augmented. Insulin by itself stimulated the phosphorylation of a single species of MW 123,000 located in the cytosol and endoplasmic reticulum. Insulin added in the presence of epinephrine significantly inhibited certain epinephrine stimulated phosphorylation, but continued to stimulate the phosphorylation of the 123,000 dalton species. The effect of insulin on this latter species thus appears to be independent of cyclic AMP. Further studies are contemplated to try to better understand the processes by which hormone signals are transmitted to the enzymatic machinery of the cell. These will include an investigation of the changes in phospholipid and prostaglandin metabolism after hormone stimulation, as well as a search for an intracellular signal ("messenger") different from CAMP that may be an intermediate with the action of insulin.

Abstract :

This project will study the role of prostaglandins and phospholipids on the mechanism of lipolysis and antilipolysis in response to hormones in adipose tissue and liver. The studies will endeavor to better understand the interrelationships between these physiological compounds and the relationship to levels of cAMP when the tissue is treated with agents that increase or decrease this metabolite. In order to carry out this project a radioimmunoassay for prostaglandin will be set up. In addition, prostaglandins will be measured in parallel by the conversion of the radioactive substrate to prostaglandin as measured by thin layer chromatography. In parallel, on thin layer, the effect of hormonal treatment on phospholipid metabolism will be studied.

Abstract :

The University Group Diabetes Program (UGDP) was undertaken for the purpose of evaluating the effect of hypoglycemic treatment on the rate of development of vascular complications in mild adult-onset diabetics. It is a multi-center study involving 12 Clinical Centers and a Coordinating Center. Patient recruitment in this study starting in February, 1961, was completed in early 1966 after a total of 1,027 patients had been enrolled. Patients were randomly assigned to one of the following treatment groups: insulin given in a fixed dose, insulin given in variable dose to maintain blood glucose levels within a normal range, tolbutamide, phenformin, or placebo. All patients were placed on diets designed to achieve or to maintain normal body weight. Information obtained from the study is used to evaluate the efficacy of treatments under study in preventing or delaying the onset and development of vascular complications in mild diabetics and to provide detailed information on the natural history of diabetes. This application is to request supplementary funds for the Coordinating Center to obtain and analyze detailed gradings of all fundus photographs available for UGDP patients. Also contained in the application is the justification for support for the 12 participating CLinical Centers for two additional years for the purpose of completing data collection under the original study protocol, providing for mortality follow-up and enabling the participation of the clinical investigators in the preparations of first reports. BIBLIOGRAPHIC REFERENCES: Knatterud, G.L., Klimt, D.R., Meinert, C.L., Osborne, R.K., Martin, D.B., Hawkins, B.S.: University Group Diabetes Program V: Evaluation of Phenformin Therapy. Diabetes 24:65-184, 1975.

Abstract :

The objective of this investigation is to study the effect of hormone on adipose tissue metabolism. Adipocytes are studied, using radioactive phosphorus to mark changes in phosphopeptide metabolism, as monitored by polyacrylamide gel electrophoresis with concomitant radioautography. Using this method on the subcellular fractions from adipocytes, it is possible to show reproducible banding of phosphopeptides. The pattern of these phosphopeptides is modified when the adipocytes are acutely (5 minute exposure) to various hormones, to date insulin and epinephrine. Epinephrine has been shown to modify the radioactivity found in two molecular weight species (of 68,000 and 120,000 Daltons) which are found in the endoplasmic reticulum and soluble portions of the adipocyte. Insulin, in turn, has been shown to augment the same 120,000 molecular weight species, but reversed the increased radioactivity found in the 68,000 molecular weight species. Physiologic correlation to define these bands is underway.

Abstract :

A plasma membrane preparation from rat adipose tissue and human erythrocytes has been prepared, which has many of the features of the glucose transport system in intact cell. The preferential uptake of H3- D-glucose when compared to C14-L-glucose retained on a millipore filter was used to mark "specific" D-glucose uptake. With the isolated plasma membrane prepations, it was observed that: 1) the D-glucose was taken up and released more rapidly than the L-isomer; 2) known inhibitors of glucose uptake inhibited the uptake of D-glucose and; 3) stereocompetitive sugars inhibited D-glucose uptake; 4) the D-glucose that was taken in the plasma membrane could be quantitatively eluted and found to be unchanged chemically; 5) the plasma membranes (in adipose tissue) on electron microscopy contained vesicles; 6) a "countercurrent" phenomenon could be demonstrated. Attempts to date to isolate the glucose transport system in the human erythrocyte preparation by using H3- and C14-dinitrofluorbenzene under conditions of the inhibition and acceleration of glucose transport (with the hope of demonstrating an enriched isotope ratio) have failed. In addition, attempts to solubilize the glucose transport system from the red cell membrane have been unsuccessful as well. Studies on insulin and adipose tissue cells are continuing. Using P32 as a marker of phosphopeptide metabolism, studies are underway to study labeling of phosphopeptides in various subcellular fractions of adipose tissue cells. It is hoped to localize the critical changes in phosphoprotein metabolism, and to define the chemical reactions involved, with particular reference to protein kinases and their molecular modifiers.

Abstract :

The University Group Diabetes Program (UGDP) was undertaken for the purpose of evaluating the effect of hypoglycemic treatment on the rate of development of vascular complications in mild adult-onset diabetes. It is a multi-clinic study involving twelve clinical centers and a coordinating center. The first grants supporting this study were awarded in 1960. Patient recruitment for this study started in February 1961 and was completed in early 1966 after a total of 1,027 patients had been enrolled. Patients were randomly assigned to one of the following treatment groups: insulin given in fixed dose, insulin given in variable dose to maintain blood glucose levels within the normal range, tolbutamide, phenformin or placebo. All patients were placed on diets designed to achieve and to maintain normal body weight. Information obtained from this study will be used to evaluate the efficacy of the treatment under study in preventing or delaying the onset and development of vascular complications in mild diabetics and to provide detailed information on the natural history of diabetes.

Abstract :

The University Group Diabetes Program (UGDP) was undertaken for the purpose of evaluating the effect of hypoglycemic treatment on the rate of development of vascular complications in mild adult-onset diabetes. It is a multi-clinic study involving twelve clinical centers and a coordinating center. The first grants supporting this study were awarded in 1960. Patient recruitment for this study started in February 1961 and was completed in early 1966 after a total of 1,027 patients had been enrolled. Patients were randomly assigned to one of the following treatment groups: insulin given in fixed dose, insulin given in variable dose to maintain blood glucose levels within the normal range, tolbutamide, phenformin or placebo. All patients were placed on diets designed to achieve and to maintain normal body weight. Information obtained from this study will be used to evaluate the efficacy of the treatment under study in preventing or delaying the onset and development of vascular complications in mild diabetics and to provide detailed information on the natural history of diabetes.