bluuebunny/crossref_metadata_2025_split huggingface dataset:
Risk Factors and Markers Associated With Proliterative Retinopathy in Patients With Insulin-Dependent Diabetes
Authors: Groop L C , Teir H , Koskimies S , Groop P -H , Matikainen E , Verkkala E , Scheinin T , Kontiainen S , Teppo A -M , Tolppanen E -M , Tallgren L G 
Published: September 2013

To define risk factors and markers associated with proliferative retinopathy (PR), we compared 44 insulindependent diabetic patients with PR with 45 matched patients without advanced retinopathy (NR). Glycemic control assessed by HbA1 measurements from 5 yr preceding diagnosis of PR was significantly worse than in NR patients. The NR patients had more frequently been treated with multiple daily insulin injections than the PR patients. About half of the PR patients had Albustix-positive proteinuria, and these patients were further characterized by an abnormal lipid profile in plasma and increased frequency of cardiovascular disease. In contrast, PR patients without proteinuria did not differ from NR patients in these variables. Sensorimotor and autonomic neuropathy were twice as frequent in the PR than in the NR group. There was no correlation between anti-insulin antibody titer, immune complexes, and the presence of PR, but T-lymphocyte response to different stimuli was slightly reduced in the PR patients. The anti-insulin-antibody titer correlated with duration of diabetes in the NR but not the PR group. The frequency of HLA-DRw8 was slightly higher in the PR group than in the NR group (16 vs. 0%, NS), but we could not confirm the previously suggested association between HLA-DR4 and PR. Serum C4 levels were low in the diabetics but did not differ between PR patients without proteinuria and NR patients.
In conclusion, poor glycemic control was clearly associated with PR in this study, and attempts to prevent this hazardous complication should include means to improve insulin therapy. We did not find support for the view that susceptibility to PR is associated with any known HLA antigen(s). Although cell-mediated immunity was slightly impaired in the PR patients, the elucidation of the role of immunologic factors in the pathogenesis of PR requires a long-term prospective Study.
Lymphocyte Subsets and Activation in Prediabetes
Authors: Hitchcock C L , Riley W J , Alamo A , Pyka R , Maclaren N K 
Published: September 2013

Peripheral blood lymphocytes were obtained from 65 individuals: 34 nondiabetic patients with islet cell autoantibodies (ICA) (prediabetic phase), 9 patients with newly diagnosed insulin-dependent diabetes mellitus (IDDM), 6 ICA-negative siblings or offsprings of IDDM patients, and 16 ICA-negative controls. The presence of lymphocyte abnormalities and/or activation was examined with dual fluorescence flow cytometry. The percentages of B cells, total T-lymphocyte, and helper T-lymphocyte (Th) and cytotoxic/suppressor T-lymphocyte (Tc/s) subsets and their ratio were not significantly different among the patient groups. No increased expression of interleukin 2 receptor on T-lymphocyte was found in newly diagnosed IDDM or prediabetic individuals. Sixteen of 49 patients had significantly increased number of T-lymphocyte expressing HLA-DR. A significant increase in the number of both Th and Tc/s subsets expressing HLA-DR was found in only 3 of 16 patients. This increase was unrelated to the patients's relative ICA titer or HLA-DR phenotype. On the other hand, the relative density of the DR antigen (RAD-DR) was significantly increased on both Th (886 ± 120) and Tc/s (1250 ± 273) in 13 of 38 patients compared with control patients (Th 484 ± 129 and Tc/s 460 ± 166). The RAD-DR on Tc/s correlated with the relative ICA titer and was greatest on DR3/4-phenotyped T-lymphocytes. In addition, significantly increased RAD-DR was found in noncontrol patients with impaired insulin release responses at 1 and 3 min to intravenous glucose.
These results suggest that the ongoing autoimmune process in the pancreas of ICA-positive pre-IDDM patients is best reflected by the appearance of increased DR antigen density on Tc/s rather than by an increased percentage of either DR or interleukin 2 receptor-positive T-lymphocytes or by abnormalities in the percentage of lymphocyte populations in the peripheral blood.
Kinetic Properties of Glycogen Synthase and Phosphorylase and Structural Aspects of Glycogen in the db / db Mouse Liver
Authors: Roesler W J , Khandelwal R L 
Published: September 2013

Kinetic studies were carried out on liver glycogen synthase and phosphorylase isolated from genetically diabetic db/db mice. Glycogen synthase a and b enzymes from diabetic mice had Vmax values 30% and 20% lower, respectively, than the enzymes from normal mice. Glycogen synthase b from diabetic mice also had a 30% lower l0.5 for Pi and ATP at physiologic concentrations of UDP-glucose (0.25 mM) compared with the normal enzyme. Kinetic studies of phosphorylase a showed that, at low glycogen concentrations (0.25 mg/ml), the Vmax of the diabetic enzyme was twofold greater than that of the normal enzyme. This was probably related to the diabetic phosphorylase a having a lower apparent Km for glycogen. This enzyme also had a slightly higher l0.5 for ATP compared with the enzyme from normal mice.
Structural studies of liver glycogen isolated from these diabetic mice showed differences from normal mouse glycogen. Both the α- and β-amylase limits were lower in the diabetic glycogen, and the average chain lengths, exterior chain lengths, and interior chain lengths calculated from these limits were all shorter in the glycogen from diabetic mice. Although both normal and diabetic glycogen absorbed light maximally at 430 nm when complexed with iodine, the absolute absorbance value was significantly lower for the diabetic glycogen. These data suggest an altered branching pattern of liver glycogen from the diabetic mice and it is suggested that this altered structure may ultimately influence the activities of glycogen-metabolizing enzymes. These results provide further characterization of the db/db mouse and show heretofore undescribed changes in phosphorylase a kinetics and glycogen Structure that occur in diabetes.
Tris(hydroxymethyl)aminomethane Inhibits the Synthesis and Processing of Proinsulin in Isolated Rat Pancreatic Islets Without Affecting Release of Insulin Stores
Authors: Halban Philippe A , Amherdt Mylene , Orci Lelio , Renold Albert E 
Published: September 2013

Isolated rat islets of Langerhans were pulse-labeled (5 min, [3H]leucine) and then exposed to 10 or 50 mM tris(hydroxymethyl)aminomethane (Tris) at pH 7.4 during an 85-min chase period. There was a dose-related inhibition of the conversion of labeled proinsulin to insulin by Tris. At 50 mM, Tris also inhibited the release of newly synthesized (labeled) proinsulin and insulin. These inhibitory effects of Tris were almost absent if the islets were exposed to 50 mM Tris during only the last 60 min of the 85-min chase period. Both proinsulin and total islet protein synthesis (as indexed by incorporation of [3H]leucine) were inhibited acutely by 50 mM Tris (5-min exposure); after 85 min of exposure to 50 mM Tris, the inhibition of proinsulin biosynthesis was more marked than that of total islet protein. In contrast to its effects on newly synthesized products, 50 mM Tris failed to inhibit the release of immunoreactive insulin during an 85-min incubation. However, when islets were exposed to 50 mM Tris for a longer period, a partial inhibition of immunoreactive insulin release was observed as from 120 min. Insulin released from islets consists of a mixture of older stored material and of newly synthesized products, the latter being released preferentially. These results are consistent with a selective effect of 50 mM Tris on the production of newly synthesized insulin. During the first 120 min of exposure to Tris, islet reserves of newly synthesized products will be depleted thereby leading to a new, reduced, rate of release of immunoreactive material consisting only of older insulin stores. To confirm that Tris neither inhibited the release of stored insulin nor exerted any nonspecific toxic effects on B-cells during prolonged exposure, islets were labeled with [3H]leucine in the absence of Tris for 3 days. The fate of the prelabeled insulin stores was then followed during a 24-h chase period in the presence of 50 mM Tris. The release of the labeled, stored insulin was not affected by Tris, whereas the release of immunoreactive insulin (consisting of both new and old material) was partially inhibited as expected.
We conclude that Tris inhibits proinsulin synthesis and processing. The inhibition of newly synthesized proinsulin release reflects perturbation of intracellular events before exocytosis, which, itself, is not affected by TriS.
Immunochemical Characterization of Anti-Islet Cell Surface Monoclonal Antibody From Nonobese Diabetic Mice
Authors: Hari Joji , Yokono Koichi , Yonezawa Kazuyoshi , Amano Kazuhiko , Yaso Shinji , Shii Kozui , Imamura Yoshimichi , Baba Shigeaki 
Published: September 2013

We have produced a monoclonal antibody 3A4 to the surface of islet cells by fusing spleen lymphocytes from nonobese diabetic (NOD) mice. To identify the molecular weight of specific target antigens reacting with 3A4, 125I-surface-labeled In-111 insulinoma cells were solubilized and extracts were absorbed with 3A4, and immunoprecipitates were followed by polyacrylamide gel electrophoresis and autoradiography. 3A4 recognized two major polypeptides with apparent molecular weights of radioactive 64K and inactive 28K. In order to evaluate the antibody-mediated cytotoxic mechanisms of 3A4, complement-dependent antibodymediated cytotoxicity (C'-AMC) and antibody-dependent cellular cytotoxicity (ADCC) were tested using a method of specific 51Cr release. In the study for C'- AMC, even over wide ranges of concentration of antibody and rabbit complement, purified 3A4 had no apparent cytotoxic effects on ln-111 cells. On the other hand, significant ADCC was observed at an antibody concentration of 10 μg/ml and a target:effector cell ratio of 1 40 (P &lt; 0.01). Finally, the effects of 3A4 on glucose-stimulated insulin release were examined in isolated rat islets. At a glucose concentration of 16.7 mM, 3A4 significantly inhibited the insulin release either in the presence or absence of complement (P &lt; 0.01).
In conclusion, 3A4 could not only bind but also be active to the target cells. Therefore, this monoclonal antibody should be a useful tool to permit a detailed analysis of the pathogenesis of type I diabetes mellitus.
Exercise Adaptation Responses for Gastric Inhibitory Polypeptide (GIP) and Insulin in Obese Children: Possible Extra-Pancreatic Effects
Authors: Kahle E Bowie , O'Dorisio Thomas M , Walker Robert B , Eisenman Patricia A , Reiser Sheldon , Cataland Samuel , Zipf William B 
Published: September 2013

Thirteen obese children and matched controls were fed a mixed meal, and responses were evaluated at fixed intervals for glucose, insulin, and gastric inhibitory polypeptide (GIP). The obese children were evaluated before and within 48 h after completion of a 5-mo exercise training program (ETP). The ETP included three aerobic exercise sessions per week and modest diet restrictions. Caloric expenditure was increased by ∼300 kcal/exercise session. Weight gain was minimal over the 5 mo. An unexpected increase in GIP response and improved insulin tolerance were recorded for the obese children post-ETP. GIP values were higher (P &lt; 0.05) at 30 and 60 min and led to a highly significant elevation (P &lt; 0.01) of the integrated GIP response for post-ETP obese versus both pre-ETP and normal-weight controls. Insulin values were lower (P &lt; 0.05) at 30 and 60 min and led to a lower integrated insulin response (P &lt; 0.0585) for post-ETP obese children. However, the obese children continued to secrete more insulin (P &lt; 0.05) than normal-weight controls. Glucose tolerance, similar for pre-ETP obese subjects and controls, did not change in post-ETP children.
Exercise-induced improvement in glucose utilization in these obese children was associated with an increase in GIP secretion. This contrasts with reports that calorie restriction will improve glucose utilization with decreased insulin and GIP secretion. The study demonstrates a previously unreported uncoupling of GIP and insulin secretion and suggests shifts in peripheral tissue sensitivity to insulin-induced glucose uptake. These shifts may, in part, be influenced by GIP.
Islet Insulin Release and Net Calcium Retention In Vitro in Vitamin D–Deficient Rats
Authors: Chertow B S , Sivitz W I , Baranetsky N G , Cordle M B , DeLuca H F 
Published: September 2013

In our previous studies, perifused islets from vitamin D-deficient (D-def) rats showed marked impairment of glucose-induced biphasic release, accounted for at least in part by a decrease in food intake. In studies reported here, we test whether D-def rat islets have an impaired response to 5.6 mM glucose or tolbutamide, (T), and if so, whether this impairment is related to a decrease in food intake or a defect in islet calcium metabolism. We isolated islets of normal rats, D-def rats, and rats pair fed (PF) to D-def rats. Biphasic insulin release from perifused islets and net 45Ca retention in lot-incubated islets were measured in response to 5.6 mM glucose, 0.37 mM T, or both.
Compared with secretion from normal islets, biphasic insulin release from islets of both D-def rats and PF rats was diminished by 50% in response to 5.6 mM glucose alone or 5.6 mM glucose plus T. Insulin secretion was not significantly different between islets of D-def rats and islets of PF rats. In contrast, net calcium retention in islets of D-def rats was decreased to 68% of retention in islets of PF rats. However, net calcium retention in islets of both PF and D-def rats increased in response to T.
The pair-feeding experiments suggest that the decrease in insulin release from islets of D-def rats is due to the decrease in food intake associated with the D-def state. On the other hand, the defect in calcium retention in islets of D-def rats raises the possibility that vitamin D may have a specific effect on islet calcium metabolism. In this case, the mechanism of impaired insulin release in islets of D-def rats would be different from that in islets of PF rats and would involve a defect in intracellular calcium handling.
Insulin-Receptor Biosynthesis in Cultured Lymphocytes From an Insulin-Resistant Patient (Rabson-Mendenhall Syndrome): Evidence for Defect Before Insertion of Receptor Into Plasma Membrane
Authors: Moncada Victoria Y , Hedo José A , Serrano-Rios Manuel , Taylor Simeon I 
Published: September 2013

In some patients with genetic forms of extreme insulin resistance, there is a marked decrease in the number of insulin receptors on the cell surface. We studied an insulin-resistant patient (RM-1) with the Rabson-Mendenhall syndrome. As judged by insulin-binding studies, Epstein-Barr virus–transformed lymphocytes from patient RM-1 exhibit a 90% decrease in the number of insulin receptors. Similarly, with either lactoperoxidase-catalyzed radioiodination of cell surface receptors or biosynthetic labeling of receptors with [3H]glucos-amine, we demonstrated an 80–90% decrease in the number of insulin receptors in cells from patient RM-1.
Previous studies have shown that the marked decrease in insulin receptors of the Rabson-Mendenhall patient is not due to accelerated receptor degradation. Therefore, we investigated the possibility that a slow rate of receptor biosynthesis might account for the 90% reduction of insulin receptors in cells from this patient.
Insulin-receptor biosynthesis proceeds through a glycoprotein precursor with an apparent M, of 190,000. It undergoes endopeptidase cleavage and further post-translational processing to yield the mature 135,000- and 95,000-Mr glycoprotein subunits. We studied the biosynthesis of the 190,000-Mr precursor and mature receptor subunits by a pulse-chase labeling technique with [2-3H]mannose. The time course of insulin-receptor biosynthesis appeared normal in cells from patient RM-1, despite a 10-fold reduction in the number of receptors on the cell surface. Parallel pulse-chase experiments with either [2-3H]mannose or [35S]methionine yielded the same results regardless of which label was employed. Thus, the receptor precursor in the Rabson-Mendenhall patient seems to be synthesized at a normal rate. Moreover, once the receptor is inserted in the membrane, it appears to be degraded at a normal rate. Therefore, we propose that there may be a defect subsequent to the synthesis of the receptor but before insertion of the receptor into the plasma membrane.
Ca2+-Mg2+-ATPase Activity in Kidney Basolateral Membrane in Non-Insulin-Dependent Diabetic Rats: Effect of Insulin
Authors: Levy J , Gavin J R , Hammerman M R , Avioli L V 
Published: September 2013

The direct effect of insulin on the high-affinity Ca2+-Mg2+-ATPase was studied in kidney proximal tubular basolateral membranes (BLM) obtained from control and streptozocin-induced non-insulin-dependent diabetes mellitus (NIDDM) rats. Plasma glucose of the diabetic animals was only mildly elevated (217 ± 9 vs. 138 ± 3 mg/dl). Both high- and low-affinity calcium-dependent Ca2+-Mg2+-ATPase activities were identified in the BLM. Enzyme activity in BLM from diabetic rats was higher at all Ca2+ concentrations tested due to a higher maximum velocity of the enzyme from NIDDM rats. The high-affinity Ca2+-Mg2+-ATPase activity was inhibited by trifluoroperzine (TFP) in both membranes. No difference in calmodulin content was found in the membranes from the diabetic and control rats.
Insulin (16–200 μU/ml) significantly increased the high-affinity Ca2+-Mg2+-ATPase activity (17–40%) in membranes from control animals but had no effect on the enzyme activity in the membranes from the NIDDM rats. The basal activity of the enzyme at 0.1 μM free Ca2+ was higher in the BLM from the NIDDM animals compared to controls (17.8 ± 0.5 vs. 14.7 ± 0.8 nM Pi mg1 · min−1; P &lt; .02). There was no effect of insulin on the Ca2+-independent ATPase activity of BLM preparations.
These findings demonstrate a defect in the ability of insulin to regulate the high-affinity Ca2+-Mg2+-ATPase activity in BLM from diabetic rats. Such a defect in enzyme activity may play a role in the mechanism of impaired insulin action observed in these NIDDM rats.
Apolipoprotein E-Containing Lipoproteins and Lipoprotein Remnants in Experimental Canine Diabetes
Authors: Wilson D E , Chan I -F , Elstad N L , Peric-Golia L , Hejazi J , Albu D S , Cutfield R 
Published: September 2013

The effects of diabetes on plasma lipoproteins were examined in a cohort of control and streptozocin-alloxan diabetic beagles fed either standard rations or an atherogenic cholesterol-supplemented diet. Lipoprotein cholesterol, triglyceride, and retinyi ester concentrations were measured in fractions separated by density gradient ultracentrifugation. Individual lipoprotein classes and apolipoproteins were assessed by electro-phoresis. Postheparin plasma lipoprotein triglyceride lipase activities were also examined.
In the absence of added dietary cholesterol, diabetic animals became hypercholesterolemic with relatively increased low-density (LDL) and decreased high-density (HDL) lipoprotein cholesterol concentrations. Apolipoprotein E-containing β- to α2-migrating HDL1 (HDLc) appeared in ρ = 1.020–1.080 g/ml subfractions, whereas α1-migrating typical HDL (ρ = 1.06–1.21 g/ml) was reduced. In comparison to nondiabetic cholesterol-fed animals, diabetic cholesterol-fed animals had increased cholesterol (but not triglyceride) concentrations in very-low- and intermediate-density classes. These classes contained retinyi esters and low-molecular-weight apolipoprotein B (components of intestinal lipoprotein remnants) as well as apolipoprotein E and high-molecular-weight apolipoprotein B. These findings could not be explained by decreased postheparin plasma lipoprotein lipolytic activities.
Increased plasma concentrations of HDLc in poorly controlled diabetic dogs may reflect a pathologic disturbance in the excretory limb of cholesterol transport from peripheral cells to the liver. In addition, exaggerated retention of lipoprotein remnants in cholesterol-fed diabetic dogs may contribute to increased delivery of cholesterol to extrahepatic tissues. This model appears to be suitable for physiologic studies of the effects of diabetes on reverse cholesterol transport.
Increase in Insulin Antibodies During Continuous Subcutaneous Insulin Infusion and Multiple-Injection Therapy in Contrast to Conventional Treatment
Authors: Dahl-Jørgensen Knut , Torjesen Peter , Hanssen Kristian F , Sandvik Leiv , Aagenæs Øystein 
Published: September 2013

Forty-five insulin-dependent diabetics were randomized to 1 yr treatment with either continuous subcutaneous insulin infusion (CSII), multiple insulin injections (MI), or continued conventional treatment. The CSII group used regular insulin only, the MI group used 4-6 premeal injections of regular insulin and intermediate insulin at night, and the conventional group used two daily injections of combined regular and intermediate insulin. Only highly purified porcine insulin was used. Near normoglycemia was obtained during CSII and MI but not during conventional treatment.
Antibodies against insulin were measured in serum samples by measuring the binding of iodinated porcine insulin to serum after removal of free and antibodybound insulin from the samples by acid charcoal. The percent binding of 125I-labeled insulin increased significantly during MI and CSII, in contrast to conventional treatment.
Nineteen patients had sufficient binding capacity for Scatchard analysis. In the CSII and MI groups, high- or low-affinity antibodies or both were induced.
When insulin was administered subcutaneously during MI or CSII for 1 yr, the insulin antibody production increased, in contrast with conventional treatment.
Free Covalent Aggregates of Therapeutic Insulin in Blood of Insulin-Dependent Diabetics
Authors: Robbins David C , Mead Patricia M 
Published: September 2013

Immunoreactive insulin (IRI) in the circulation of diabetics using insulin includes a 12,000-Mr covalent aggregate of insulin. In this study, both free and bound IRI were measured in nine type I diabetics who were treated sequentially for 3 wk with constant doses of conventional beef-pork, biosynthetic human, and beefpork insulins (phases 1, 2, and 3, respectively).
The aggregate accounted for 19 ± 5.7, 38 ± 7.7, and 26 ± 7% of bound IRI, and 19 ± 8.3, 35 ± 7.3, and 31 ± 5.0% of free IRI during phases 1, 2, and 3, respectively. Taken as concentrations (μU/ml), the absolute amounts of aggregate in the bound fraction were significantly (P &lt; .001) greater than those that were free, whereas the ratios of aggregate to monomer within each pool were similar (P &gt; .1). The relative and absolute amounts of the insulin aggregate during each of the three treatment phases (compared by analysis of variance) were indistinguishable (P &gt; 0.5). However, the aggregate was overestimated by a factor of ∼2 when measurements were made on the basis of an insulin- monomer standard.
We conclude that both the bound and free fractions of IRI contain insulin aggregate. Overreactivity of the aggregate in the radioimmunoassay contributes to the so-called hyperinsulinism of type I diabetes. As with insulin monomer, most of the 12,000-Mr aggregate is bound to antibodies. Because some of the aggregate is free, its biologic consequences must be assessed.