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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have shown previously that prolonged exposure to insulin and glucose impairs the insulin-responsive glucose transport system in primary cultured adipocytes. To assess the ability of insulin and glucose to regulate other cellular insulin actions, epididymal rat adipocytes were cultured in media containing 0-15 mM D-glucose and with or without insulin (50 ng/ml). After 24 h, cells were washed and basal and maximally insulin-stimulated rates of 2-deoxy-D-glucose uptake, L-leucine incorporation into protein, glucose oxidation to CO2, glucose incorporation into lipids, and glycogen synthase activity were measured. The results confirmed that glucose potentiates insulin's chronic ability to decrease basal and maximal glucose transport rates by approximately 50% at 5 mM glucose and by approximately 70% at 15 mM glucose compared with control cells. However, neither glucose nor insulin, alone or in combination, affected rates of leucine incorporation into protein. In addition, basal and maximal rates of glucose oxidation and of glucose incorporation into lipids were not regulated by glucose, and maximal responses declined approximately 50% over 24 h only when insulin was not present during preincubation (i.e., chronic insulin exposure was necessary to maintain full maximal responses). Glycogen synthase activity was measured in a cell-free system (0.5 mM UDP-glucose, with 10 or 0.01 mM glucose-6-phosphate) after exposing intact cells to glucose and insulin. Both short-term (1 h) and long-term (24 h) exposure to glucose alone led a dose-dependent increase in I-form and D-form glycogen synthase activity. Chronic exposure to insulin also increased total glycogen synthase activity (I- plus D-form) but did not affect absolute rates of maximally stimulated I-form activity. Glucose (but not insulin) increased the cellular content of immunoreactive glycogen synthase by 70% after 1 h. These results show that 1) chronic exposure to glucose and insulin impairs insulin responsiveness of the glucose transport system but does not affect rates of amino acid incorporation into protein; 2) the chronic presence of insulin is necessary for the maintenance of normal maximally stimulated rates of glucose oxidation and of glucose incorporation into lipids in cultured cells; and 3) glucose increases both D-form and I-form glycogen synthase activity, in part by increasing the amount of synthase protein, whereas chronic insulin exposure increases total glycogen synthase activity without altering maximal absolute rates of I-form activity.(ABSTRACT TRUNCATED AT 400 WORDS)
Diabetes 1994 Jan
PMID:Biological actions of insulin are differentially regulated by glucose and insulin in primary cultured adipocytes. Chronic ability to increase glycogen synthase activity. 826 17

To investigate the pathogenesis of spontaneously diabetic Chinese hamsters of Asahikawa colony (CHAD), hepatic glucose production (HGP) and glucose uptake of several tissues were determined before the onset of hyperglycemia (prediabetic state). HGP was calculated as glucose disposal in postabsorptive state using [3-3H]glucose. Glucose uptake of various tissues was assessed as glucose utilization index (R'g) by the 2-deoxyglucose method. Plasma insulin level was increased in prediabetic CHAD but not decreased in CHAD with short-term diabetes compared with control Chinese hamsters (non-diabetic strain). HGP of prediabetic CHAD was similar to that of control Chinese hamsters. However, after developing overt hyperglycemia (> 200 mg/100 ml), HGP increased linearly with plasma glucose level. R'g of adductor longus, extensor digitorum longus and triceps was significantly decreased in prediabetic CHAD. R'g of interscapular brown adipose tissue, white adipose tissue from inguinal, dorsal and epididymal sites were also decreased in prediabetic CHAD. Thus, peripheral insulin resistance precedes the development of hyperglycemia and may be a primary defect in CHAD. No significant difference of R'g in heart ventricle, diaphragm, tibialis anterior or brain was observed. In conclusion, insulin resistance in some muscles and brown and white adipose tissues precedes hyperglycemia and hepatic insulin resistance in CHAD. Hepatic overproduction of glucose (hepatic insulin resistance) is a major factor responsible for overt basal hyperglycemia and may play an important role in developing further diabetic state.
Diabetes Res Clin Pract 1993 May
PMID:Peripheral insulin resistance precedes the onset of hyperglycemia in spontaneously diabetic Chinese hamsters of Asahikawa colony. 837 62

The activity of adipose tissue hormone-sensitive lipase in animals with hyperinsulinemia has been reported to be increased compared with that in control animals. We examined whether this results from a direct effect of insulin on the tissue and whether it is accompanied by alteration in the regulation of lipolysis. When rat epididymal fat pads are incubated in culture medium with bovine serum albumin for 2-4 h with 2 ng/ml or 50 microU/ml of insulin, hormone-sensitive lipase activity in the postmicrosomal supernatant fraction after acid precipitation and activation with ATP-Mg2+ increases significantly compared with preparations from tissues incubated with the vehicle. The specific activities of hormone-sensitive lipase in sonicates of adipocytes after primary culture with insulin at concentrations from 10 to 4000 ng/ml (250 microU to 100 mU/ml) increase in an insulin-dose-related manner. Lipolysis in response to 10(-7) M isoproterenol also increases in an insulin-dose-dependent manner. Enhancement of isoproterenol-mediated lipolysis is not attributable to a difference in the triglyceride content of the cells. Lipolysis caused by the beta-agonist could be completely blocked by the simultaneous presence of insulin in both control and insulin-treated cells reflecting normal responsiveness of both types of cells to the acute effect of insulin. Although an increase in lipolysis is seen with norepinephrine and growth hormone after insulin treatment, other lipolytic agents such as ACTH, thyrotropin, and glucagon evoke similar responses in insulin-treated and control cells. The simultaneous presence of growth hormone and insulin during the 16-h culture results in additive effects on the subsequent response of the cells to 10(-7) M isoproterenol compared with the responses of the cells cultured with each hormone alone. beta-Agonist-mediated cAMP accumulation in the presence of Ro-20.1724, a specific phosphodiesterase inhibitor, is significantly higher in cells cultured in the presence of insulin than in control cells. Forskolin (1-25 microM) increases the lipolytic responses of insulin-treated cells compared with control cells, but the maximal response of the insulin-treated cells to forskolin is lower than that to isoproterenol. We conclude that changes produced by chronic insulin treatment involve more than one site along the lipolytic cascade.
Diabetes 1993 Oct
PMID:Chronic exposure of rat fat cells to insulin enhances lipolysis and activation of partially purified hormone-sensitive lipase. 839 27

The effect of streptozotocin induced diabetes and sabeluzole (SBZ) on sexual function was evaluated in male rats. SBZ is a benzothiazole derivative with antihypoxic and antiischaemic activities. Rats were rendered diabetic by intraperitoneal injection of streptozotocin, 60 mg./kg. body weight, and either left untreated or treated with 1.0 mg./kg. of SBZ. Two groups of control rats treated with or without SBZ were also evaluated. Seven weeks after the induction of diabetes, all rats were studied in vivo for mating behavior. Animals were sacrificed one week later, and detrusor strip response in vitro was evaluated. The reproductive organ weight, sperm content and motility as well as in vitro testosterone secretion and serum levels of LH and testosterone were determined. Diabetes induced significant reduction in mating behavior. The diabetic rats that received SBZ showed a significant improvement in mating behavior. The percentage of animals that exhibited ejaculation was 0% in the diabetic group compared to 70% in the controls and 38% in diabetic plus SBZ group. The strips of the detrusor muscle of the diabetic group showed a marked hypersensitivity to bethanechol HCL. In the diabetic plus SBZ group, the strips of the detrusor muscle showed a response similar to that of the control. The diabetic rats had significantly diminished reproductive organ weight, testicular sperm content, epididymal sperm content and sperm motility relative to the control. In addition, marked decrease in the serum level of testosterone and in vitro testosterone secretion was observed in diabetic rats. In the diabetic plus SBZ group, the reproductive organ weight, sperm content and motility as well as serum testosterone and in vitro testosterone secretion showed an improvement compared to diabetic rats. In summary, our data suggest that sex behavior and reproductive tract functions are markedly affected by streptozotocin induced diabetes. Sabeluzole treatment could be beneficial in reducing the deleterious effect of diabetes on sexual functions.
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PMID:The effect of diabetes on sexual behavior and reproductive tract function in male rats. 841 1

The effects of englitazone in male Wistar rats fed a high-fat diet (59% of calories as fat) were compared with control rats fed a high-carbohydrate diet (69% of calories as carbohydrate) (5-15 animals per group). Insulin-stimulated (17 nmol/l) 2-deoxy-D-glucose (2-DG) uptake was inhibited 31% in adipocytes isolated from rats on the high-fat diet for 3 weeks, but englitazone (50 mg/kg for the last 7 days) normalized the response. There was a selective decrease in GLUT4 (54 +/- 5% of high-carbohydrate) in epididymal fat from rats on the high-fat diet for 3 weeks, but englitazone treatment did not reverse the defect in GLUT4 (43 +/- 8% of high-carbohydrate) or increase GLUT1 (81 +/- 12% of high-carbohydrate). Englitazone normalized oral glucose (1 g/kg body wt) intolerance and excessive (210% of high-carbohydrate) liver glycogen deposition (from [14C]glucose) caused by the high-fat diet. The high-fat diet tended to decrease insulin receptor substrate-1 (IRS-1) and phosphatidylinositol-3'-kinase (PI-3-kinase) expression in epididymal fat (26% decrease; P < 0.1). Englitazone did not reverse this decrease in IRS-1 and PI-3-kinase levels in fat from high-fat-fed rats (there was a further 25-30% decrease, P < 0.05), nor did it increase PI-3-kinase activity in 3T3-L1 adipocytes under conditions (48 h incubation) where it stimulated 2-DG uptake sixfold or enhanced insulin-stimulated 2-DG uptake. In summary, englitazone prevented the insulin resistance associated with a high-fat diet, but the mechanism of action does not involve changes in fat or muscle glucose transporter content and may not involve activation of the insulin signaling pathway via PI-3-kinase.
Diabetes 1996 Jan
PMID:The antihyperglycemic agent englitazone prevents the defect in glucose transport in rats fed a high-fat diet. 852 61

A 65-year-old diabetic man presented with a painful swelling of his right epididymis. Urine culture was sterile. Semicastration was performed and histology revealed malacoplakia of the epididymis without involvement of the testis. Histologic workup demonstrated typical von Hansemann cells and Michaelis-Gutmann bodies stained by von Kossa's stain. This is the 19th case of epididymal malacoplakia and the 9th case of epididymal malacoplakia without concurrent involvement of the testis. Literature review shows that the present case is typical with respect to the clinical presentation and with regard to the age of presentation. The fact that this patient was suffering from diabetes mellitus lends some support to the assumption that a compromised immune status could be etiologic in malacoplakia.
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PMID:Malacoplakia of the epididymis. Report of a case and review of the literature. 858 71

We measured levels of ob mRNA in epididymal fat pads of rats exposed to manipulations designed to alter circulating insulin and glycemia. Changes in ob mRNA were compared to alterations in GLUT-4 glucose transporter mRNA, which is known to be regulated under these conditions. 48 h fasting decreased GLUT-4 mRNA to 23% of control with restoration beginning by 6 h refeeding and full restoration at 24 h. In contrast, ob mRNA decreased less markedly to 47% of control with only partial restoration by 24 h. Two days of streptozocin (STZ)-diabetes (glucose > 400 mg/100 ml) decreased GLUT-4 mRNA to 8% of control with restoration by two days of S.C. insulin. In contrast, ob mRNA decreased to 42% of control and was not restored by insulin. Six days of insulin administration to normal rats under conditions of ad lib. feeding, but without otherwise preventing the blood glucose from decreasing, resulted in no significant change in levels of either ob or GLUT-4 mRNA.
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PMID:Rat adipose ob mRNA levels in states of altered circulating glucose and insulin. 860 98

Mutation of the obese (ob) gene results in severe hereditary obesity and diabetes in the C57BL/6J and related strains of mice. In this study we examined the expression of the ob gene in a dietary model in which moderate obesity develops in response to fat (58% of calories from fat) without mutation of the ob gene, and in four genetic models of obesity in mice: ob/ob, db/db, tubby, and fat. Several white and brown adipose depots were examined (epididymal, subcutaneous, perirenal, and interscapular). Northern blot analysis shows that levels of ob mRNA are increased in all adipose depots examined in every model of obesity. The average fold increases were 12.0 +/ 2.1 (ob/ob), 4.8 +/- 1.5 (db/db), 2.8 +/- 0.1 (tubby), 2.4 +/- 0.3 (fat), and 2.1 +/- 0.2 (high fat diet-induced A/J). Moreover, we found that the expression of the ob gene could be manipulated by pharmacologically blocking the development of diet-induced obesity. Supplementation of a high fat diet with a beta 3-adrenergic receptor agonist (CL316,243) prevented obesity, but not hyperphagia associated with high fat feeding (body weights of high fat-fed A/J mice = 34.0 +/- 1.0 g; high fat plus CL316,243-fed mice = 26.8 +/- 0.5 g; n = 10). CL316,243-treated, high fat-fed animals contained levels of ob mRNA in all adipose depots that were equal to or less than levels in low fat-fed mice (average levels in high fat plus CL316,243-fed mice relative to low fat-fed mice: 0.93 +/- 0.09). Inasmuch as fat cell size, but not number, was increased in a previous study in diet-induced obese A/J mice, these results indicate that expression of the ob gene serves as a sensor of fat cell hypertrophy, independent of any effects on food intake.
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PMID:Pharmacologic manipulation of ob expression in a dietary model of obesity. 862 12

There is a correlation between circulating insulin levels and blood pressure over a wide range of insulin levels and in a variety of clinical conditions. Production of prostaglandin (PG)E(2) (PGE(2)) and prostacyclin (PGI(2)), two potent vasodilators, by adipose tissue is increased in severe insulin deficiency, eg, diabetic ketoacidosis (DKA), explaining the decreased peripheral vascular resistance in DKA. Conversely, decreased production of PGE(2) and PGI(2) may mediate the relationship between hyperinsulinemia and hypertension. Although insulin inhibits PG production in normal rat adipose tissue, PG production in adipose tissue from patients or experimental animals with nonketotic diabetes mellitus (DM) and DKA has not been studied. We examined the effect of plasma insulin levels on blood pressure and on adipose tissue PG production in rats with DM and DKA and normal rats. There was a significant relationship between plasma insulin level and blood pressure in rats with DM and normal controls (P < .021) and in rats with DKA and normal controls (P < .0001). There was an inverse linear correlation between plasma insulin levels and basal 6-keto-PGF(1 alpha) production by a mixture of adipocytes and endothelial cells from epididymal adipose tissue in rats with DKA and normal rats (P < .0252, R2 = .67). Rates of basal glycerol, PGE(2), and 6-keto-PGF(1alpha) production by a mixture of adipocytes and endothelial cells from epididymal adipose tissue were significantly higher in rats with DKA than in normal rats. These rates were also higher in rats with DM than in normal rats, but only glycerol values were statistically significant. In rats with DM, PGE(2) production induced by epinephrine 2 x 10(-5) mol/L (but not lower concentrations) was significantly greater than basal production (P < .05); production of 6-keto-PGF(1alpha) was not stimulated. In rats with DKA, 6-keto-PGF(1alpha) production induced by epinephrine 2 x 10(-5) mol/L (but not lower concentrations) was significantly greater than basal production (P < .05); production of PGE(2) was not stimulated. We conclude the following: (1) there is a close correlation between circulating insulin level and systemic blood pressure when rats with DM and DKA are compared with controls; (2) in insulin deficiency, PGI(2) and PGE(2) production are increased in adipose tissue versus normal tissue; and (3) the correlation between insulin level and blood pressure may be mediated by the inhibitory effect of insulin on vasodilative PG production by adipose tissue.
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PMID:The relationship between plasma insulin level, prostaglandin production by adipose tissue, and blood pressure in normal rats and rats with diabetes mellitus and diabetic ketoacidosis. 863 42

Immunoisolation of xenogeneic pancreatic islets within membrane-bound devices has been proposed as an approach to cure diabetes. We examined the local response to implanted xenografts and allografts in comparison with isografts in diffusion chambers with 0.4-microm pore membranes when implanted into epididymal fat pads of rats. These membranes prevented host cell entry into the device but did not prevent passage of large molecules such as IgG and IgM. Well-differentiated allogeneic tissues (Sprague-Dawley rat embryonic lung implanted into Lewis rats) survived for 1 year when implanted in intact devices, but similar tissues were destroyed within 3 weeks when implanted within devices with holes poked in the membrane to allow host cell contact. In contrast, xenografts (CF1 mouse embryonic lung implanted into Lewis rats) were destroyed within 3 weeks even when implanted in devices with intact membranes. The death of the xenogeneic tissues was accompanied by a severe local accumulation of inflammatory cells and a decrease in local vascularization. When isogeneic tissues (Lewis rat embryonic lung implanted in Lewis rats) were mixed with xenogeneic tissues, a local inflammatory response occurred and both iso- and xenogeneic tissues were destroyed within 5 weeks. These results suggest the possibility that xenografts are killed by local accumulation of inflammatory cells, perhaps mediated by the release of antigens from the tissues within the device and presentation by an indirect pathway. The observation that the local response to xenografts is sufficient to kill isografts complicates issues of immunoprotection, suggesting that successful immunoisolation will require membranes that not only provide protection of the encapsulated tissues from the host immune system but also have properties that diminish the release of xenogeneic antigens.
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PMID:Local inflammatory response around diffusion chambers containing xenografts. Nonspecific destruction of tissues and decreased local vascularization. 868 42


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