[Emergency drug therapy of diabetic coma].
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Acidosis, Lactic↗
Biomedical subjects
M Kasuga
Publications and source records attributed to M Kasuga.
Delayed gastric emptying in bulimic patients.
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Adult↗
Analysis of the structural features of the C-terminus of GLUT1 that are required for transport catalytic activity.
C-terminally truncated and mutated forms of GLUT1 have been constructed to determine the minimum structure at the C-terminus required for glucose transport activity and ligand binding at the outer and inner binding sites. Four truncated mutants have been constructed (CTD24 to CTD27) in which 24 to 27 amino acids are deleted. In addition, point substitutions of R468-->L, F467-->L and G466-->E have been produced. Chinese hamster ovary clones which were transfected with these mutant GLUT1s were shown, by Western blotting and cell-surface carbohydrate labelling, to have expression levels which were comparable with the wild-type clone. Wild-type levels of 2-deoxy-D-glucose transport activity were retained only in the clone transfected with the construct in which 24 amino acids were deleted (CTD24). The CTD25, CTD26 and CTD27 clones showed markedly reduced transport activity. From a kinetic comparison of the CTD24 and CTD26 clones it was found that the reduced transport was mainly associated with a reduced Vmax. value for 2-deoxy-D-glucose uptake but with a slight lowering of the Km. These data establish that the 24 amino acids at the C-terminus of GLUT1 are not required for the transport catalysis. However, the point mutations of F467L and G466E (26 and 27 residues from the C-terminus) did not significantly perturb the kinetics of 2-deoxy-D-glucose transport. The substitution of R468L produced a slight, but significant, lowering of the Km. The ability of the truncated GLUt1s to bind the exofacial ligand, 2-N-4-(1-zai-2,2,2-trifluoroethyl)benzoyl-1,3-bis-(D-mannos- 4-yl-oxy) -2-propylamine (ATB-BMPA), and the endofacial ligand, cytochalasin B, were assessed by photolabelling procedures. The ability to bind ATB-BMPA was retained only in the CTD24 truncated mutant and was reduced to levels comparable with those of the non-transfected clone in the other mutant clones. Cytochalasin B labelling was unimpaired in all four mutated GLUT1s. These data establish that a minimum structure at the C-terminus of GLUT1, which is required for the conformational change to expose the exofacial site, includes amino acids at positions Phe-467 and Arg-468; however, these amino acids are not individually essential.
Affinity Labels↗
Localization and subcellular distribution of SH-PTP2, a protein-tyrosine phosphatase with Src homology-2 domains, in rat brain.
SH-PTP2 is a protein-tyrosine phosphatase with src homology-2 (SH2) domains and shown to be highly expressed in the rat brain. Light microscopic immunohistochemistry showed that specific immunoreactivity was widely distributed, most abundant in neurophil, weak in neuronal somata, and absent from white matter. By electron microscopic immunohistochemistry, intense labeling is observed on synapses and concentrated in the pre- and post-synaptic plasma membranes. In subcellular fractionation analysis of brain, SH-PTP2 was mainly observed in the particulate fraction, particularly in myelin and synaptosomes. SH-PTP2 was further recovered in the synaptic plasma membrane. SH-PTP2 was extracted from brain membrane with a detergent such as Triton X-100 or Nonidet P-40 but not with 1 M NaCl. Furthermore, SH-PTP2 was coimmunoprecipitated with a 100 kDa tyrosine-phosphorylated membrane protein, which may couple SH-PTP2 to brain membranes. These results suggest that SH-PTP2 associates with synaptic membranes and may play a role in the synaptic communications in the brain.
Animals↗
Ras-independent and wortmannin-sensitive activation of glycogen synthase by insulin in Chinese hamster ovary cells.
Activation of glycogen synthase is one of the major metabolic events triggered by exposure of cells to insulin. The molecular mechanism by which insulin activates glycogen synthase was investigated. The possible role of Ras and mitogen-activated protein kinase cascade was investigated with a stable cell line, CHO-IR-C/S 46, that overexpresses insulin receptors and a catalytically inactive SH-PTP 2 protein phosphatase and in which insulin does not induce the formation of the Ras-GTP complex or the subsequently activation of the mitogen-activated protein kinase cascade. Insulin activated glycogen synthase in this cell line to a similar extent as in parental CHO-IR cells. The importance of heteromeric phosphoinositide (PI) 3-kinase in insulin activation of glycogen synthase was examined in a stable cell line, CHO-IR/delta p85, that overexpresses insulin receptors and a dominant negative mutant (delta p85) of the 85-kDa subunit of PI 3-kinase that lacks the binding site for the catalytic 110-kDa subunit. Insulin-dependent activation of PI-3 kinase and glucose transport, but not the formation of the Ras-GTP complex, are markedly attenuated in this cell line. In CHO-IR/delta p85 cells, insulin activated glycogen synthase to a similar extent as in parental CHO-IR cells. The failure of overproduction of the mutant (delta p85) protein to inhibit insulin activation of glycogen synthase was also confirmed by transient expression in Rat 1 cells with the use of a recombinant vaccinia virus. However, wortmannin abolished insulin activation of glycogen synthase in all cell lines. These data suggest that existence of a Ras-independent and wortmannin-sensitive pathway for activation of glycogen synthase by insulin.
Androstadienes↗
[Suspected case of lupus cystitis with successful early treatment].
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Cystitis↗
EGF-induced activation of 70-kDa S6 kinase in CHO cells expressing human EGF receptors.
We investigated epidermal growth factor (EGF)-induced activation of 85-kDa/110-kDa phosphatidylinositol (PI)-3-kinase and 70-kDa S6 kinase in Chinese hamster ovary cells expressing the human EGF receptor. EGF-induced activation of p70 S6 kinase was comparable to that induced by insulin, whereas that of PI-3-kinase in anti-phosphotyrosine immunoprecipitates was very small compared with insulin. Wortmannin, a p85/p110 PI-3-kinase inhibitor, inhibited EGF-induced activation of p70 S6 kinase in a dose-dependent manner. Given that several proteins homologous to catalytic subunit of p85/p110 PI-3-kinase have been identified and that wortmannin inhibits distinct form of PI-3-kinase, the present results suggest that wortmannin-sensitive kinases that resemble catalytic subunit of p85/p110 PI-3-kinase may participate in the signaling pathway from EGF receptors to p70 S6 kinase.
Androstadienes↗
Requirement for phosphoinositide 3-kinase in insulin-stimulated GLUT4 translocation in 3T3-L1 adipocytes.
Insulin stimulates glucose transport in muscle and fat cells by inducing the redistribution of a specific glucose transporter, GLUT4, from intracellular vesicles to the cell surface. Phosphoinositide (PI) 3-kinase has been implicated as a key intermediate in insulin-stimulated glucose transport by studies that have examined the effects of wortmannin and LY294002, which are thought to be specific inhibitors of this enzyme. However, the specificity of these compounds for PI 3-kinase has recently been questioned. Epidermal growth factor, which activates mitogen-activated protein kinase in mouse 3T3-L1 adipocytes, has now been shown to have no effect on PI 3-kinase activity or GLUT4 translocation in these cells. Furthermore, microinjection of a dominant negative mutant of the 85-kDa subunit of PI 3-kinase, which lacks a binding site for the catalytic 110-kDa subunit, inhibited GLUT4 translocation induced by insulin in 3T3-L1 adipocytes; microinjection of the wild-type protein had no effect. These observations indicate that PI 3-kinase is necessary for insulin-induced GLUT4 translocation and glucose transport in adipocytes.
3T3 Cells↗
Phosphoinositide 3-kinase as an upstream regulator of the small GTP-binding protein Rac in the insulin signaling of membrane ruffling.
Membrane ruffling and the closely linked response of fluid-phase pinocytosis were investigated in Chinese hamster ovary cells that stably overexpress the human insulin receptor and a mutant 85-kDa subunit of phosphoinositide (PI) 3-kinase (delta p85) that lacks a binding site for the catalytic 110-kDa subunit of this enzyme. Both membrane ruffling and pinocytosis induced by insulin were markedly impaired in these cells. Microinjection of Rac, a Ras-related small GTP-binding protein, induced membrane ruffling in human epidermoid carcinoma KB cells, and this effect of Rac was not blocked by coinjection of delta p85 or by exposure of cells to wortmannin, a specific PI 3-kinase inhibitor. These results suggest that PI 3-kinase is essential not only for insulin-stimulated membrane ruffling but also for pinocytosis, and that PI 3-kinase possibly functions upstream of Rac in the signal transduction pathway.
Animals↗
Normal activation of p70 S6 kinase by insulin in cells overexpressing dominant negative 85kD subunit of phosphoinositide 3-kinase.
The role of heteromeric phosphoinositide (PI) 3-kinase activity in insulin signal transduction was studied by investigating the effects of (i) overexpression of a dominant negative mutant p85 (delta p85) that lacks the binding site for p110 (delta p85-overexpressing cells) and (ii) inhibition of PI 3-kinase activity by wortmannin (wortmannin-treated cells). The insulin-induced association of PI 3-kinase activity with insulin receptor sustrate-1 (IRS-1) was inhibited in both wortmannin-treated cells and delta p85-overexpressing cells. However, whereas insulin-induced activation of p70 S6 kinase was completely abolished in wortmannin-treated cells, it appeared normal in delta p85-overexpressing cells. These results raise the possibility that a wortmannin-sensitive pathway independent of heteromeric PI 3-kinase is involved in the activation of p70 S6 kinase by insulin.
Amino Acid Sequence↗
A convulsant, 3-mercaptopropionic acid, decreases the level of GABA and GAD in rat pancreatic islets and brain.
To investigate the properties of the gamma-aminobutyric acid (GABA) synthesizing enzyme, glutamate decarboxylase (GAD), in the brain and the pancreatic islets of the rat, GABA concentration in the brain and the pancreatic islets was measured after intraperitoneal administration of 3-mercaptopropionic acid (3-MP) at 25 mg/kg. 60 min after the administration of 3-MP, GABA concentration in the hypothalamus, the superior colliculus and the hippocampus of the brain decreased by 20-30% and in the pancreatic islets by 35%. The concentration in the pancreatic acini did not change. Western blotting showed that GAD activity in the pancreatic islets decreased after administration of 3-MP compared to the control. The activity of GAD in the pancreatic islets as well as brain can be modified by a convulsant, in this case 3-MP. These results suggest the properties of GAD may be similar in the pancreatic islets and brain.
3-Mercaptopropionic Acid↗
Mitochondrial mutation in diabetic patient with gastrointestinal symptoms.
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Adult↗
Diabetes mellitus carrying a mutation in the mitochondrial tRNA(Leu(UUR)) gene.
We screened 214 Japanese NIDDM (non-insulin-dependent) diabetic patients with a family history of diabetes for mutations in the mitochondrial tRNA(Leu(UUR)) gene using polymerase chain reaction-restriction fragment length polymorphism and direct sequencing. Six patients were identified as having an A to G transition at position 3243 (3243 mutation), but no patients were detected with a T to C transition at position 3271, in the mitochondrial tRNA(Leu(UUR)) gene. These two mutations were not present in 85 healthy control subjects. It was disclosed that the patients' mothers were also affected by diabetes mellitus in five of the six cases. In these six affected patients, the 3243 mutation shows variable phenotypes, such as the degree of multiple organ involvement, intrafamilial and interfamilial differences in disease characteristics, and the degree of the involvement of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) phenotype. Endocrinological examinations revealed that those diabetic patients with the 3243 mutation show not only beta-cell dysfunction, but also a defect in alpha-cell function, which is considered characteristic of diabetes with the 3243 mutation. When compared with 50 selected diabetic control subjects without the 3243 mutation, whose mothers, but not fathers, were found to have diabetes, it was established statistically that those with the 3243 mutation possess the following clinical characteristics; 1) the age of diabetes onset is lower, 2) they have lean body constitutions, and 3) they are more likely to be treated with insulin than control subjects. We suggest that diabetes with the 3243 mutation possesses phenotypes distinct from those in common forms of diabetes.
Adolescent↗
Response of glutamic acid decarboxylase to glucose but not arginine in islets.
This study examined responses of glutamic acid decarboxylase (GAD65) and gamma-aminobutyric acid (GABA) to glucose in pancreatic islets. Islets isolated from Wistar rats were cultured for the three days under different concentrations of glucose (5.6, 11.1 or 16.7 mM) or arginine (2 x 10(-1)-2 x 10(-4) mM) for different periods of time. The expression of GAD65 increased 3.8- and 4.5-fold with the elevation of glucose concentrations as well as the prolongation of culture periods of time, while it did not increase with arginine. GABA content of islets did not change in a range of 5.6 to 16.7 mM glucose. These results suggest that normalization of hyperglycemia would reduce the expression of the autoantigen in islets, which might prevent islets from further destruction. To the contrary, the persistent hyperglycemia could interfere with insulin synthesis not by change of GABA in islets but by the destruction of islets through GAD65 expression.
Animals↗
Long-term efficacy and tolerability of pravastatin in hypercholesterolemia in patients with non-insulin-dependent diabetes mellitus. Hyogo Pravastatin Study Group.
This study reports the result of a 12-month, open-label multicenter study of the efficacy and tolerability of pravastatin in the management of hypercholesterolemia associated with non-insulin-dependent diabetes mellitus. Pravastatin produced a decrease, in 138 diabetic and 51 non-diabetic patients, in total serum cholesterol by 19 and 20%, in low-density lipoprotein (LDL) cholesterol by 25 and 29%, in apolipoprotein B by 15 and 19% and in triglycerides by 8 and 5%, respectively. High-density lipoprotein cholesterol levels were increased by 9% in both groups. All of these changes were significant (P < 0.001) except for triglycerides changes in non-diabetic patients, where the change was not significant and no significant differences were observed between the two groups. These favorable effects on LDL cholesterol and apolipoprotein B were not influenced by gender, the type of diabetic therapy, baseline hemoglobin A1c levels and by the presence of hypertension or gross proteinuria, although a decrease in the two variables were less in those with body mass index > or = 26.4 kg/m2 or in those with age < 60 years. Adverse experiences were similar between treatment groups and the drug was well tolerated. Only one diabetic patient was withdrawn from the study because of pruritus. Pravastatin produced no change in fasting plasma glucose concentrations and hemoglobin A1c levels in diabetic patients throughout the study. Pravastatin was generally effective in improving the serum lipids of hypercholesterolemic diabetic patients.
Adult↗
A novel function of islet-derived CD8+T cells in initiating and developing autoimmune insulin-dependent diabetes mellitus in non-obese diabetic (NOD) mice.
Accumulated studies revealed that CD4+T cells were initially required for diabetes in NOD mice, whereas interaction of CD4+T/CD8+T cells is not fully understood. To address this question, we established islet-derived CD4+T cells and CD8+T cells from NOD mice. One NOD neonate that received CD4+T cells developed diabetes and insulitis with CD8+T cells. Administration of cyclophosphamide to non-diabetic recipients accelerated the development of diabetes, while none of the mice with anti-CD8 antibody did so. Similarly, it was observed that neonates that received islet-derived CD8+T cells developed diabetes and obvious insulitis mainly with CD4+T cells. Administration of anti-CD4 antibody with transfer of CD8+T cells inhibited insulitis. These results imply that CD8+T cells function as an initial element to recruit CD4+T cells to islets as well as a final effector.
Animals↗
Long-term effects of simvastatin in hypercholesterolemic patients with NIDDM and additional atherosclerotic risk factors. Hyogo Simvastatin Study Group.
Effects of 12 months of simvastatin treatment were examined in 48 NIDDM patients with total serum cholesterol levels exceeding 220 mg/dl and were compared with those in 35 nondiabetic patients with hypercholesterolemia. In the diabetic group, 5-10 mg of simvastatin given once daily at bedtime significantly lowered total cholesterol (21%). LDL cholesterol (28%), apoB (15%) and triglycerides (8%) levels. These changes were identical to those in the nondiabetic group, except for triglycerides which did not change significantly. HDL cholesterol increased significantly in the nondiabetic group but not in the diabetic group. The reductions in LDL cholesterol and apoB in hypercholesterolemic patients with NIDDM were not influenced by gender, age, glycemic control, the presence or absence of systemic hypertension, obesity and overt proteinuria. In addition, the decrease in LDL cholesterol was not affected by the number of risk factors per patient. Simvastatin did not significantly alter hemoglobin A1c or fasting plasma glucose and was well tolerated in both groups. Simvastatin produced beneficial effects on serum lipids and apolipoproteins and neutral effects on glycemic control in hypercholesterolemic patients with NIDDM, whether or not they had an additional atherosclerotic risk factor.
Anticholesteremic Agents↗
Evaluation of gastric ulcer healing by lansoprazole by measurement of ulcer diameter.
Ninety-three patients with gastric ulcers larger than 10 mm in diameter were randomly divided into two groups. Seventy patients received lansoprazole 30 mg once daily and 23 patients received cimetidine 400 mg twice daily. Ulcer healing was assessed by measuring changes in the longitudinal diameter of the ulcer at 2, 4, and 8 weeks after the start of treatment. In the lansoprazole group, ulcer diameters became significantly smaller than those in the cimetidine group. In the lansoprazole group, ulcer diameters did not differ significantly between patients younger than 65 years of age and those 65 or older at the evaluation points. However, in the cimetidine group, ulcer diameters became much smaller in patients younger than 65 years of age than in older patients. These results suggest that the potent acid suppression afforded by lansoprazole led to effective healing of gastric ulcers even in elderly gastric ulcer patients with defective mucosal protection.
2-Pyridinylmethylsulfinylbenzimidazoles↗