bluuebunny/crossref_metadata_2025 huggingface dataset:
Insulin Resistance and Impaired Insulin Secretion in Subjects with Histories of Gestational Diabetes Mellitus
Authors: Ward W Kenneth , Johnston Colin L W , Beard James C , Benedetti Thomas J , Halter Jeffrey B , Porte Daniel
Published: September 2013

NIDDM is characterized by decreased insulin secretory responses to glucose and to nonglucose stimuli, hyperglucagonemia, and decreased tissue sensitivity to insulin. However, it hasbeen unclear which of these abnormalities, if any, precedes the others. Since women with histories of gestational diabetes mellitus (GDM) are at high risk for eventual development of NIDDM, we measured B- and A-cell function and tissue sensitivity to insulin in eight normoglycemic, postpartum women with recent histories of GDM and in eight control subjects pair-matched for age and percent of ideal body weight.

Fasting plasma glucose levels in subjects with former GDM tended to be slightly higher than in matched controls (98 ± 3 versus 92 ± 2 mg/dl, P = 0.07). Basal plasma insulin in subjects with former GDM was significantly higher than in controls (22 ± 4 versus 14 ± 2 μUml, P = 0.05). During an intravenous glucose tolerance test (IVGTT), relative first- and second-phase insulin responses to glucose were decreased in subjects with former GDM (2316 ± 560 versus 7798 ± 1036% of basal · min, P = 0.004; and 8340 ± 946 versus 14,509 ± 2556, P = 0.04). An index of sensitivity to insulin, S1, calculated from the IVGTT, was also lower in former GDM (1.23 ± 0.69 × 10 4 versus 3.58 ± 0.78 × 10−4 min−1μU/ml, P = 0.001).

Acute insulin responses to 5 g i.v. arginine were measured at plasma glucose levels of approximately 95, 215, and 600 mg/dl. The response at 600 mg/dl is termed the AIRmax andis used asan index of glucoseregulated insulin secretory capacity. Insulin responses to arginine at all glucose levels were similar in both groups. However, AIRmax, which was inversely correlated with S1 in controls, appeared low for the degree of insulin resistance informer GDM. Glucagon responses to arginine obtained at normoglycemia and suppressibility of such responses by hyperglycemia (600 mg/dl) were similar in both groups.

We conclude that women with histories of GDM, who are predisposed to NIDDM, have impairments both of insulin secretion and of insulin action before the development of overt hyperglycemia.
Correlates of Insulin Antibodies in Newly Diagnosed Children with Insulin-dependent Diabetes Before Insulin Therapy
Authors: Arslanian S A , Becker D J , Rabin B , Atchison R , Eberhardt M , Cavender D , Dorman J , Drash A L
Published: September 2013

Insulin antibodies, as measured by plasma radiolabeled insulin-binding capacity, were determined in 124 newly diagnosed insulin-dependent diabetic (IDDM) children before and after 1, 3, and 5 days of insulin therapy. Controls were 35 nondiabetic children with plasma insulin binding capacity of 1.0 ± 0.7%. The patients were divided into three groups according to their plasma insulin-binding capacity. Group 1 (N = 79) had binding within two standard deviations (SD) of the control mean, group 2 (N = 20) had insulin binding 2–6 SD above controls, and group 3 (N = 25) showed insulin-binding capacity of more than 6 SD above the control mean. After exogenous insulin therapy, plasma 125I-insulin-binding capacity dropped significantly in both groups 2 and 3, concurrent with significant increases in plasma insulin levels. The three groups differed from each other in that patients in group 3 were significantly younger thanin the other groups and clinically seemed to be more severely dehydrated, as reflected in their higher levels of serum urea nitrogen, plasma glucose, potassium, and elevated pulse rate. The three groups did not differ in respect to sex, HLA-DR antigens, Coxsackie-B antibody titers, islet cell cytoplasmic antibodies, immunoglobulin level, and C-peptide levels. Only two of 446 siblings of IDDM children showed elevated insulin binding, one of whom developed IDDM 6 wk later. The presence of an insulin-binding substance probably representing insulin antibodies in some cases of newly diagnosed IDDM suggests that autoimmunity in this disorder is not limited to the B-cell membrane and cytoplasm and lends further support to the heterogeneity Of IDDM.
A Particular Subset of HLA-DR4 Accounts for All or Most of the DR4 Association in Type I Diabetes
Authors: Sheehy M J , Rowe J R , MacDonald M J
Published: September 2013

Two human T-lymphocyte clones, derived from a mixed leukocyte culture (MLC) with stimulating cells from a type I diabetic patient, define a subset of HLA-DR4, tentatively called “DR4S.” In testing of 69 random type I diabetic subjects and 69 random controls, 79% (37/47) of DR4-positive patients, but only 44% (8/18) of DR4-positive controls, had DR4S (P < 0.01). The relative risk of type I diabetes for DR4S+ individuals was 8.8,while that for DR4+ DR4S− individuals was only 1.0. Thus, in the populationtested, DR4S accounts for all or most of the increased frequency of HLA-DR4 in type I diabetes.
Structure of the Human Erythrocyte Insulin Receptor
Authors: Ward Glenn M , Harrison Len C
Published: September 2013

The structure of the insulin receptor in intact human erythrocytes was defined using the techniques of disuccinimidyl suberate (DSS) cross-linking of 125I-insulin and surface [125I]iodination followed by receptor immunoprecipitation. In contrast to a recent report, we found the erythrocyte insulin receptor to be similar in structure to that in classic target tissues for insulin, consisting of at least three species of molecular weight approximately 295,000, 265,000, and 245,000, containing disulfide-linked subunits of molecular weight approximately 130,000 and 95,000. The interconversion of the three oligomeric forms could mediate changes in receptor affinity as postulated in other tissues. The 95,000 subunit was detected by immunoprecipitation only if surface iodination was performed in a Tris/Hepes buffer using lodogen and not if phosphate-buffered saline or lactoperoxidase iodination was used. These findings indicate that the lack of a bioeffect of insulin in erythrocytes is not explained by a gross defect in the structure of their insulin receptors. The apparent identity of the insulin receptor structure in erythrocytes and insulin target tissues provides a firmer basis for the use of erythrocytes in some circumstances to reflect insulin receptor status.
Opioid Peptides in Rat Islets of Langerhans: Immunoreactive Met- and Leu-Enkephalins and BAM-22P
Authors: Timmers Kim I , Voyles Nancy R , King Clifford , Wells Michael , Fairtile Richard , Recant Lillian
Published: September 2013

Previous studies have shown that met- and leu-enkephalins are present in extracts of whole pancreas obtained from guinea pigs and human cadavers. The present studies demonstrate that immunoreactive methionine5 (met)- and leucine5 (leu)-enkephalins present in rat pancreas are localized in islets of Langerhans. Immunohistochemical staining of fixed, whole pancreas indicated that only islet endocrine cells were heavily stained when any of four different met- and leuenkephalin-directed antisera or an anti-BAM-22P (bovine adrenal medulla docosapeptide) antiserum was used. The peptides were characterized by a combination of gel-filtration chromatography, high-performance liquid chromatography (HPLC), and specific radioimmunoassay. Free met-enkephalin content in extracts of rat islets was 90-fold enriched over content in extracts of whole pancreas (1.72 ± 0.35 versus 0.019 ± 0.007 pmol/mg protein). Treatment with trypsin and carboxypeptidase-B of high-molecular-weight peptides extracted from pancreas or islets resulted in release of additional met-enkephalin immunoreactivity, which was 39-fold enriched in islets compared with pancreas (5.90 ± 0.58 and 0.153 ± 0.032 pmol/mg protein, respectively). Total islet content (per milligram protein) of met-enkephalin-containing peptides was similar to that reported elsewhere for bovine hypothalamus. The immunohistochemical data as well as the enrichment of extractable enkephalins in islets compared with whole pancreas indicate that essentially all the met-enkephalin present in pancreas is localized in islets, while the presence of BAM-22P immunoreactivity in islets is consistent with biosynthesis of enkephalins in islet cells via a preprohormone, such as that described in the bovine adrenal medulla and rat brain.
Calcitonin Inhibition of Insulin Release from Isolated Rat Pancreatic Islets
Authors: Alwmark Anders , Stavinoha Michael W , Cooper Cary W , Greeley George H , Thompson James C
Published: September 2013

Calcitonin is known to inhibit secretion of gastrin and insulin in vivo. The objective of this study was to determine whether calcitonin can act directly on pancreatic islets in vitro to inhibit insulin release. Isolated islets were obtained from collagenase-treated rat pancreas, and three peptides (gastrin-releasing peptide, cholecystokinin-8, bombesin) and glucose were used to stimulate insulin release. All agents caused a significant increase in insulin secretion and calcitonin inhibited these responses, but had no consistent effect on basal release. This study provides evidence that calcitonin is an effective inhibitor of insulin secretion and acts directly on islet tissue.
New Diabetogenic Streptozocin Analogue, 3-O-Methyl-2-{[(methylnitrosoamino) carbonyl]amino}-D-glucopyranose: Evidence for a Glucose Recognition Site on Pancreatic B-Cells
Authors: Kawada Jun , Toide Kiyotaka , Nishida Mikio , Yoshimura Yoshiyuki , Tsujihara Kenji
Published: September 2013

The nonmetabolizable glucose analogue 3-O-methylglucose is known to protect pancreatic B-cells against streptozocin (STZ) when injected with or just before STZ. If 3-O-methyl-glucose and the sugar moiety of STZ compete for a glucose recognition site on B-cells, it seemed likely that 3-O-methyl-2-deoxy-2-{[(methylnitrosoamino) carbonyl]amino}-D-glucopyranose, an analogue of STZ with a 3-O-methyl-glucosyl residue, would cause experimental diabetes. This possibility was tested by synthesis of this analogue (α-anomer) and comparison of its diabetogenic activity in Wistar rats with that of STZ. Results showed that the compound was diabetogenic and as potent as STZ. This new analogue is the first of the various STZ derivatives reported to show diabetogenic activity. Its activity supports the idea that 3-O-methyl-glucose and STZ bind competitively with a glucose recognition site on pancreatic B-cells.
The Effect of Cyclosporin-A, Low-Temperature Culture, and Anti-la Antibodies on Prevention of Rejection of Rat Islet Allografts
Authors: Terasaka Reiji , Lacy Paul E , Hauptfeld Vera , Bucy R Pat , Davie Joseph M
Published: September 2013

The effect of cyclosporin-A, low-temperature culture, and anti-la antibodies on prevention of rejection of rat islet allografts was determined. Wistar-Furth islets were isolated by the collagenase technique and transplanted via the portal vein into diabetic Lewis recipients. Cyclosporin-A (30 mg/kg) injected at 0, 1, and 2 days after transplantation produced a significant prolongation of survival of the islet allografts (MST > 35.7 ± 7.0 days) when hand-picked donor islets were used, whereas only a modest prolongation of survival (14.0 ± 1.6 days) was obtained using donor islets removed directly from Ficoll gradients. This difference in survival was apparently due to the large number of lymphoid, antigen-presenting cells that were present in the islet fraction removed directly from the Ficoll gradients. Treatment of donor, hand-picked islets with a mixture of cross-reactive anti-la antibodies and complement without cyclosporin-A therapy did not prolong the survival of islet allografts (MST, 6.5 ± 0.4 days versus 7.0 ± 0.5 days in controls). In contrast, treatment of the donor islets with the mixture of anti-la antibodies and complement in conjunction with the 3-day course of cyclosporin-A therapy produced an 83% survival of the islet allografts at 60 days after transplantation. In vitro culture of hand-picked donor islets at 24°C for 7 days and the 3-day course of cyclosporin-A therapy produced a 100% survival of the allografts at 60 days after transplantation. These findings indicate that rejection of rat islets transplanted into a strain with strong immune responsiveness (Lewis) can be prevented by a combination of temporary immunosuppression of the recipients with cyclosporin-A and pretreatment of the donor islets with either cross-reactive anti-la antibodies or culture of the islets at 24°C for 7 days before transplantation.
Platelet-Density Analysis and Intraplatelet Granule Content in Young Insulin-Dependent Diabetics
Authors: Collier A , Watson H H K , Matthews D M , Strain L , Ludlam C A , Clarke B F
Published: September 2013

This study was designed to assess the density characteristics of platelets from controls (N = 10) and three groups of diabetics (N = 32) exhibiting various degrees of glycemic control. With continuous gradients of Percoll, platelets from controls and diabetics (N = 8) with an HbA1 ≤ 9% formed a band extending from 1.0625 g/ml to 1.0925 g/ml with a mean platelet density of 1.0775 g/ml. In the two groups of diabetics with HbA1 ≥ 10%, there was an increase in the proportion of low-density platelets recovered on the gradients and the mean platelet density was reduced to 1.0750 g/ml (HbA1 = 10–13%) and 1.070 g/ml (HbA1 ≥ 14%). All three groups of diabetics had normal levels of intraplatelet ATP/ADP and β-thromboglobulin. It is unlikely that in vivo degranulation of platelets after activation was responsible for the altered density profiles. We propose that abnormal platelet subpopulations with low density but normal intraplatelet granule content were responsible for the changed density profiles.
New α2-Adrenergic Blocker (DG-5128) Improves Insulin Secretion and In Vivo Glucose Disposal in NIDDM Patients
Authors: Kashiwagi A , Harano Y , Suzuki M , Kojima H , Harada M , Nishio Y , Shigeta Y
Published: September 2013

Effects of oral administration of DG-5128, a new oral hypoglycemic agent, on glycemic control after a mixed meal and an in vivo glucose disposal were measured in subjects with nonobese non-insulin-dependent diabetes mellitus (NIDDM). Oral administration of DG-5128 significantly (P < .05) enhanced insulin secretion both 30 and 60 min after a mixed meal (550 kcal), with a concomitant decrease in postprandial plasma glucose levels at 60 and 120 min. Glucose disposal rate between the 2nd and 4th h of a euglycemic insulin clamp, developed through a constant infusion of insulin (0.77 mil · kg−1 · min−1) together with somatostatin (80 ng · kg−1 · min−1), was 2.5-fold higher in a DG-5128-treated group (P < .01) than in a control group. However, there was no difference between the two groups in either plasma glucose concentration or plasma insulin concentration at either the 2nd or the 4th h. These results indicate that DG-5128 is effective in controlling plasma glucose levels in subjects with NIDDM by stimulation of both insulin secretion and in vivo glucose disposal.
Comparison of Two Methods of Islet Preparation and Transplantation in Dogs
Authors: Hesse U , Sutherland D E R , Florack G , Field J , Ward S , Najarian J S
Published: September 2013

Seventy-nine mongrel dogs underwent total pancreatectomy. Fifteen dogs served as apancreatic controls and died 7.0 ± 4.2 days later (mean ± SD). The pancreases of 44 dogs (group 1) were intraductally distended by manual injection of Hanks' balanced salt solution (HBSS). Thereafter each organ was mechanically disrupted and subjected to collagenase digestion as described by Mirkovitch et al.8 The pancreases of 20 dogs (group 2) were intraductally distended and subsequently perfused with collagenase by a roller pump. The organs were then mechanically disrupted and filtered through screens as described by Horaguchi et al.9 The resulting tissue suspensions were injected into the spleens of the dogs as autotransplants in both groups, by direct punction of the splenic capsule in group 1 and by retrograde infusion via a splenic vein tributary in group 2. The functional outcome was better in group 2 than in group 1, as assessed by the number of animals that became normoglycemic after transplantation [15/20 (75%) vs. 13/44 (30%); P = .0025]. The degree of islet purification, as measured by an increase in the tissue insulin/amylase ratio, was higher in group 2, and in both groups it was higher in normoglycemic than in hyperglycemic animals. The percent engraftment [i.e., amount of insulin recovered from spleen as percent of tissue transplanted (mean, 15.4% in group 1 and 14.5% in group 2) or as percent of original pancreas (mean, 4.9% in group 1 and 4.4% in group 2)] was low in both groups but again was higher in normoglycemic than in hyperglycemic animals within each group. In conclusion, both the degree of engraftment and purification and the route of implantation influenced the functional outcome after dispersed pancreatic islet autotransplantation to the spleen of totally pancreatectomized dogs, with purified tissue injected retrogradely functioning better than unpurified tissue injected directly.
Glomerular Proteoglycans in Diabetes: Partial Structural Characterization and Metabolism of De Novo Synthesized Heparan-35SO4 and Dermatan-35SO4 Proteoglycans in Streptozocin-Induced Diabetic Rats
Authors: Klein D J , Brown D M , Oegema T R
Published: September 2013

The metabolism of glomerular proteoglycans was studied in an effort to understand the mechanisms leading to reduction of glomerular basement membrane (GBM) heparan sulfate (heparan-SO4) proteoglycan in diabetes. Glomeruli were isolated from control and streptozocin-induced diabetic rats after exposure to [35S]sulfate. A pool of rapidly metabolized 35S-glycosaminoglycans (GAG), predominantly heparan-35SO4, was present in GBMs from controls but not diabetics, whereas intact isolated glomeruli from the two groups contained similar quantities of 35S-macromolecules after 4 and 16 h in vitro. Glomeruli from diabetics contained less 35S-proteoglycan than controls after 16 h in vivo. A more rapid disappearance of [35s[sulfate from serum and an increased inorganic sulfate concentration in diabetes may account for this difference.

Glomeruli from diabetics contained more heparan-35SO4 and less dermatan-35SO4 proteoglycan than control glomeruli in vitro. Diabetic glomerular heparan-35SO4 proteoglycan and its GAG chains had hydrodynamic sizes similar to controls (Mr, 13 and 1.25 × 104, respectively). A heparin-releasable heparan-35SO4 proteoglycan detected in isolated control glomeruli by gel electrophoresis was present in chase medium of glomeruli from diabetics in the absence of heparin.

Two dermatan-35SO4 proteoglycans were synthesized in vitro. One had size and charge properties similar to glomerular heparan-35SO4 proteoglycan. A second, larger dermatan-35SO4 proteoglycan accumulated in tissue over 16 h. It was partially excluded from Sepharose CL-6B columns and eluted from Sepharose CL-4B columns at Kav = 0.32. The hydrodynamic sizes of both tissue forms of dermatan-35SO4 proteoglycan were similar in diabetics and controls.

Differences in the biochemical characteristics of the major de novo synthesized glomerular proteoglycan pools could not be invoked to explain altered metabolism of GBM heparan sulfate in diabetic animals. These changes may result from diminished affinity of heparan sulfate proteoglycan for extracellular matrix or cell surfaces and may account for altered glomerular ultrafiltration properties in diabetes mellitus.
Myocardial Cell Dysfunction in Diabetes Mellitus: A Review of Clinical and Experimental Studies
Authors: Gøtzsche O
Published: September 2013

Evidence for an abnormal myocardial cell function in diabetes mellitus, influenced by acute metabolic changes, has appeared within recent years. Few but interesting clinical studies focus on this aspect of diabetic cardiopathy, and experimental studies have delivered possible explanations at the cellular level. These are concerned with the intracellular calcium homeostasis and transsarcolemmal receptor signaling. Because these changes are reversible by short-term insulin treatment, a new aspect for the study of diabetic heart disease has appeared.
Interferon-Mediated Induction of la Antigen Expression on Isolated Murine Whole Islets and Dispersed Islet Cells
Authors: Wright J R , Lacy P E , Unanue E R , Muszynski C , Hauptfeld V
Published: September 2013

Islets from male B10.BR mice (H-2k) were isolated by the collagenase technique, handpicked with a Pasteur pipette, and incubated (either intact or after dispersion with Dispase) for 0, 3, 5, 7,10, or 14 days in tissue culture medium supplemented with either lymphokine supernatants or recombinant murine interferon-γ. Islets and single cells were examined for IAk molecules by use of indirect immunofluorescence. la-positive islet cells were identified on the surface of islets incubated with 5–10% lymphokine for >4 days or with 10,100, or 1000 ng/ml interferon for >6 days. Islets incubated in unsupplemented medium were la negative. Incubation with 5% lymphokine induced la expression on 10–40% dispersed islet cells cultured for >9 days. Dual immunofluorescent staining for la and insulin revealed that la-positive cells included both β- and non-β-cells.
Effect of Aldose Reductase Inhibitor (Sorbinil) on Integration of Polyol Pathway, Pentose Phosphate Pathway, and Glycolytic Route in Diabetic Rat Lens
Authors: Gonzalez A -M , Sochor M , Hothersall J S , McLean P
Published: September 2013

This study examines the effect of an aldose reductase inhibitor (sorbinil) on the flux of specifically labeled glucose through alternative pathways of metabolism in the lens of normal and diabetic rats 1 wk after the induction of diabetes with alloxan. In the diabetic rat lens, there was an apparent increase in the flux of glucose through the pentose phosphate pathway (PPP), as measured by the difference in the yields of 14CO2 from]1-14C[glucose and [6-14C]glucose [C1–C6], this value was 0.087 ± 0.005 and 0.263 ± 0.034 μmol · g lens−1 · h (mean + SE of 6 values) for control and diabetic rats, respectively; sorbinil treatment decreased the values to 0.065 ± 0.008 and 0.171 ± 0.028, respectively. With glucose tritiated on carbon 2 or 3, it has been shown that the flux of glucose through the polyol route is increased, whereas the flux through the glycolytic pathway is decreased in the diabetic rat lens; both are restored toward normal in the sorbinil-treated diabetic group. These results suggest that the dual effects of diabetes in increasing 1) the lens content of glucose and glucose 6-phosphate and 2) the flux of glucose in the polyol pathway will result in an increased utilization of NADPH and production of NADH, factors favoring the flow of glucose through the PPP and restricting the glycolytic route in the diabetic rat lens. The inhibition of aldose reductase by sorbinil tends to normalize the redox state of the nicotinamide nucleotides, reimposing the NADPH limitation on the PPP and increasing the availability of NAD+ for the glycolytic route.
Glutathione Redox State Is Not the Link Between Polyol Pathway Activity and Myo-Inosltol–Related Na+-K+-ATPase Defect in Experimental Diabetic Neuropathy
Authors: Carroll P B , Thornton B M , Greene D A
Published: September 2013

Decreased glutathione levels in the ocular lens have been invoked as a possible cause for the decreased lenticular Na+-K+-ATPase in diabetes because both are corrected by aldose reductase inhibitors, and the Na+-K+-ATPase is known to be susceptible to oxidation inactivation. Because an analogous Na+-K+-ATPase defect that is prevented by aldose reductase inhibitors has been described in diabetic peripheral nerve, we examined the effect of streptozocin (STZ) diabetes and aldose reductase inhibition on reduced (GSH) and oxidized (GSSG) glutathione levels in crude homogenates of rat sciatic nerve. Neither GSSG nor GSH levels were altered by 2 or 8 wk of untreated diabetes or by aldose reductase inhibition. Because the defect in Na+-K+-ATPase is fully expressed by 4 wk of STZ diabetes, we conclude that altered glutathione redox state plays no detectable role in the pathogenesis of this defect in diabetic peripheral nerve.
Glucose Transport by Radiation-Induced Insulinoma and Clonal Pancreatic β-Cells
Authors: Meglasson M D , Manning C D , Najafi H , Matschinsky F M
Published: September 2013

Sugar uptake was measured in dispersed cells prepared from radiation-induced insulinomas transplantable in NEDH rats and in three clonal β-cell lines maintained in continuous culture (RIN m5F, RIN 1046, HIT). Uptake of D-glucose and 3-O-methyl-D-glucose by insulinoma cells was rapid so that the intracellular concentration of D-hexoses approximated the concentration in the incubation medium by 15–30 s. L-Glucose was taken up only slowly. 3-O-methyl-D-glucose uptake by RIN m5F, RIN 1046, and HIT cells was slow; with 1 mM 3-O-methylglucose in the medium, equilibrium was attained at 20 min, but with 10 mM 3-O-methylglucose, equilibrium was not attained even at 20 min. In HIT cells incubated with D-glucose for 30 min, the intracellular concentration of glucose was less than the medium glucose concentration, indicating glucose transport is a nonequilibrium reaction in this cell line. These data indicate that radiation-induced insulinoma cells retain the capacity of normal β-cells to transport sugar at high rates. RIN m5F, RIN 1046, and HIT cells transport sugar slowly, however, and thus differ from normal β-cells. In RIN m5F, RIN 1046, and HIT cells, unlike in normal β-cells, glucose transport may be the site regulating glucose metabolism.
Cysteine Analogues Potentiate Glucose-Induced Insulin Release In Vitro
Authors: Ammon H P T , Hehl K -H , Enz G , Setiadi-Ranti A , Verspohl E J
Published: September 2013

In rat pancreatic islets, cysteine analogues, including glutathione, acetylcysteine, cysteamine, D-penicillamine, L-cysteine ethyl ester, and cysteine–potentiated glucose (11.1 mM) induced insulin secretion in a concentration-dependent manner. Their maximal effects were similar and occurred at ∼0.05, 0.05, 0.1, 0.5, 1.0, 1.0 mM, respectively. At substimulatory glucose levels (2.8 mM), insulin release was not affected by these compounds. In contrast, thiol compounds, structurally different from cysteine and its analogues, such as mesna, tiopronin, meso-2,3-dimercaptosuccinic acid (DMSA), dimercaprol (BAL), β-thio-D-glucose, as well as those cysteine analogues that lack a free-thiol group, including L-cystine, cystamine, D-penicillamine disulfide, S-carbocysteine, and S-carbamoyl-L-cysteine, did not enhance insulin release at stimulatory glucose levels (11.1 mM); cystine (5 mM) was inhibitory. These in vitro data indicate that among the thiols tested here, only cysteine and its analogues potentiate glucose-induced insulin secretion, whereas thiols that are structurally not related to cysteine do not. This suggests that a cysteine moiety in the molecule is necessary for the insulinotropic effect. For their synergistic action to glucose, the availability of a sulfhydryl group is also a prerequisite. The maximal synergistic action is similar for all cysteine analogues tested, whereas the potency of action is different, suggesting similarity in the mechanism of action but differences in the affinity to the secretory system.
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.
Altered Red and White Blood Cell Rheology in Type II Diabetes
Authors: Ernst E , Matrai A
Published: September 2013

Twenty-three patients suffering from type II, non-insulin-dependent diabetes were compared with matched controls. Suspensions with standardized white and red cell counts were filtered in a novel device capable of discriminating filter occlusion and cell transit time. Results confirm previous studies indicating that red cell deformability is impaired in diabetes. According to our findings, this may be caused by a slight overall loss of red cell fluidity together with the existence of a subpopulation of more markedly rigid erythrocytes. Furthermore, we demonstrate that white cell filterability is reduced in type II diabetes. This could be due to decreased white cell deformability, increased white cell adhesion, or both. Analysis of diabetic subgroups indicates that the white cell rheology is impaired to a greater extent in patients taking oral antidiabetic drugs than in patients controlled by diet alone. Altered white cell rheology could help to explain the pathological blood cell filterability frequently reported in diabetes. More important, impaired white cell rheology might significantly contribute to microcirculatory flow abnormalities jeopardizing O2 exchange in the terminal vascular bed.
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.
Glucose Utilization Rates and Insulin Sensitivity In Vivo in Tissues of Virgin and Pregnant Rats
Authors: Leturque Armelle , Ferre Pascal , Burnol Anne-Françoise , Kande Joseph , Maulard Paulette , Girard Jean
Published: September 2013

In vivo studies have shown that insulin resistance in late pregnancy results from a decreased sensitivity of liver and peripheral tissues. In the present study, measurements of the rates of glucose utilization by skeletal muscles (soleus, extensor digitorum longus, epitrochlearis, and diaphragm), white adipose tissue, and brain of virgin and 19-day pregnant rats were performed in the basal condition and during a euglycemic, hyperinsulinemic (400 μU/ml) clamp to quantify the partition of glucose utilization and to identify the tissues other than liver responsible for insulin resistance. Fetal and placental glucose utilization rates were also measured in pregnant rats. The fetal glucose utilization rate (22 mg/min/kg) was very high and was not stimulated by physiologic maternal hyperinsulinemia. By contrast, the placental glucose utilization rate (29 mg/ min/kg) was increased by 30% during hyperinsulinemia. The glucose utilization rate of the conceptus represented 23% of the maternal glucose utilization rate in the basal state. Glucose utilization rates in the basal condition were not statistically altered by pregnancy in brain, skeletal muscles, and white adipose tissue. During hyperinsulinemia (400 μU/ml), glucose utilization rates in extensor digitorum longus, epitrochlearis, and white adipose tissue were 30–70% lower in pregnant than in virgin rats. Insulin sensitivity of glucose metabolism in all the tissues tested other than brain was 50% lower in pregnant than in virgin rats. We conclude that skeletal muscles and, to a smaller extent, adipose tissue are involved in the insulin resistance of late pregnancy.
Platelet Fibrinogen Binding in Diabetes Mellitus: Differences Between Binding to Platelets from Nonretinopathic and Retinopathic Diabetic Patients
Authors: Diminno Giovanni , Silver Melvin J , Cerbone Anna M , Riccardi Gabriele , Rivellese Angela , Mancini Mario
Published: September 2013

While it is known that platelets from diabetic patients bind more fibrinogen than do platelets from normal subjects, there has been no study comparing this phenomenon in platelets from nonretinopathic and retinopathic patients. We have made such a comparison and have found the following. In agreement with previous reports, platelets from nonretinopathic diabetic patients bind abnormally high amounts of fibrinogen. No differences in the amount of fibrinogen bound to platelets (stimulated by collagen or thrombin) were found when data from nonretinopathic and retinopathic patients were compared. However, while aspirin (an inhibitor of thromboxane synthesis) reduced the abnormally high fibrinogen binding of platelets from nonretinopathic patients to normal control levels, it did not normalize the high fibrinogen binding of platelets from retinopathic diabetic patients. The combination of aspirin plus apy-rase (an ADP scavenger) almost suppressed fibrinogen binding and aggregation of platelets from normal or nonretinopathic diabetic subjects, whereas it had a somewhat lesser effect on binding and aggregation of platelets from retinopathic subjects. By using a monoclonal antibody (B59.2) to the platelet receptor for fibrinogen, we determined that this receptor was the same in platelets from normal as well as nonretinopathic diabetic subjects and that this antibody could suppress the binding of fibrinogen and the aggregation of platelets from both types of patients just as it did in platelets from normal subjects. Thus, our data indicate that, while platelets from both retinopathic and nonretinopathic patients are hyperaggregable and show abnormally high binding of fibrinogen, they differ in that these abnormalities can be normalized in platelets from nonretinopathic patients by suppressing prostaglandin/ thromboxane formation and scavenging AOP, but not in those from retinopathic patients.
T-Lymphopenia and T-Cell Imbalance in Diabetic db/db Mice
Authors: Boillot D , Assan R , Dardenne M , Debray-Sachs M , Bach J F
Published: September 2013

The diabetic db/db mice of the C57 BL/KsJ strain display anti-islet immunity, thymic dysfunction, and lymphopenia. In the present work, lymphocytes, T-cells, and T-cell subsets were enumerated in thymus and spleen from diabetic db/db mice and their db/ + heterozygote I irte r m ates from the 10th day to the 10th month of life. A significant lymphopenia was detected in thymus and spleen from the second month on, involving specifically the T-cell compartment, as assessed by use of a monoclonal anti-Thy1 antibody in indirect fluorescence. The study of T-cell subsets by monoclonal anti-Lyt1 and anti-Lyt2 antibodies revealed a significant increase in Lyt1+ cells and a decrease in Lyt2+ cells, with a corresponding increase of the Lyt1 + /Lyt2+ ratio. These anomalies appeared early in life, and were apparently linked neither with the degree of hyperglycemie nor with weight loss or infection. The T-cell depletion in thymus was more pronounced in young male (<3 mo) than in young female db/db mice. These alterations may correspond to an increase in the helper/ suppressor-cytotoxic ratio and could be linked with the thymic anomalies present in these mice, contributing to the development of anti-islet autoimmunity.
Marked Depletion of Plasma 1,5-Anhydroglucitol, a Major Polyol, in Streptozocin-induced Diabetes in Rats and the Effect of Insulin Treatment
Authors: Yamanouchi Toshikazu , Akanuma Hiroshi , Takaku Fumimaro , Akanuma Yasuo
Published: September 2013

Plasma levels of 1,5-anhydroglucitol (1,5AG), a major polyol resembling glucose in structure, fell rapidly and dramatically in streptozocin (STZ)-treated rats. 1,5AG fell immediately after STZ injection, reaching a plasma level 6 h after administration of the drug that was one-third that in the plasma of control rats. Reduction of 1,5AG was independent of the profile of blood glucose induced by STZ. After intravenous injection of [14C]-1,5AG, its plasma half-life was determined to be between 120 and 180 min. After a phase of acute decrease, the reduction of 1,5AG became gradual, stopping within 6 days after treatment. However, in some cases, the drop in 1,5AG was partially reversible by insulin treatment. The extent to which 1,5AG fell did not strictly correspond to the dose of STZ. The particular organ(s) consuming or accumulating 1,5AG was not identified. However, aside from the large amount of 1,5AG in plasma and the small amount of 1,5AG in the urine, the liver appears to be a significant organ for metabolism Of 1,5AG.
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.
Skeletal Growth in Fetal Rats: Effects of Glucose and Amino Acids
Authors: Heinze E , Brenner R , Nguyen-Thi Ch , Vetter U , Leupold D , Pohlandt F
Published: September 2013

The modified hyperglycemia-hyperinsulinism hypothesis, which characterizes intrauterine growth of diabetic pregnancy, was studied in fetal rats. From day 19 to day 21 postconception, pregnant rats were constantly infused with saline, amino acids, or glucose. In the fetus, serum somatomedin activity was determined, with the porcine bioassay and the incorporation of 3H-thymidine into rib cartilage and isolated chondrocytes in vivo in response to serum from normal maternal or fetal rats. In comparison with control fetuses, body weights were decreased in glucose-exposed fetuses (4.66 ± 0.25 versus 3.75 ± 0.99, N = 121; P < 0.001), and increased (4.87 ± 0.57, N = 105; P < 0.05) in amino acid-exposed fetuses. Serum somatomedin activity (U/ml) was higher in glucose-treated (0.79 ± 0.40, N = 11; P < 0.05) and amino acid-treated animals (0.90 ± 0.16, N = 10; P 0.001) than in controls (0.55 ± 0.04, N = 13). In vivo labeling with thymidine resulted in a higher radioactivity of cartilage in small fetuses compared with large fetuses when the dams had been infused with saline (r = –0.531, N = 56; P < 0.001) or amino acids (r = –0.292, N = 52; P < 0.01). Opposite results were obtained in hyperglycemie animals (r = 0.542, N = 54; P < 0.001). When isolated chondrocytes were incubated with serum from. normal fetal rats, the incorporation of thymidine was about 10 times higher into cells from small fetuses than from large fetuses, irrespective of the infusion regimen. In parallel experiments chondrocytes from the same cell pool were incubated with serum from normal pregnant rats. In these experiments the isotope incorporation into chondrocytes was enhanced in small and large fetuses from saline- or amino acid-treated mothers. In contrast, the thymidine incorporation into isolated chondrocytes from small hyperglycemie fetuses was significantly inhibited by normal maternal serum. The results confirm the many observations in fetal rats that a moderate or severe hyperglycemia during pregnancy decreases fetal body weight and that an increased somatomedin activity, as measured with adult tissues (such as in the porcine bioassay), may not be associated with increased body weight or length. Second, it appears that the growth-promoting activity of fetal serum differs from that of adult serum. Third, similar to adult hyperglycemie rats, an inhibition of the thymidine incorporation into cartilage of small hyperglycemie fetal rats was Observed.
Islet Cell Proteins Defined by Monoclonal Islet Cell Antibody HISL-19
Authors: Srikanta S , Krisch K , Eisenbarth G S
Published: September 2013

A monoclonal islet cell antibody, HISL-19, reactive with human, bovine, and porcine pancreatic islets has been used to identify and characterize a novel group of islet cell proteins (p120, p69, p67, and p56). Besides the islets, HISL-19-reactive antigenic determinants are also expressed on selected cell types, namely, gut endocrine cells, thyroid parafollicular cells (p120), anterior pituitary cells (p40 and p24), specific hypothalamic neuroendocrine cells, and a single layer of large pyramidal cells of the cerebral cortex, thus defining a new family of neuroendocrine molecules.
Kinetics of Biosynthetic Human Proinsulin Action in Isolated Rat Adipocytes
Authors: Ciaraldi Theodore P , Brady David , Olefsky Jerrold M
Published: September 2013

The binding and biologic potencies of human biosynthetic proinsulin (HPro) were determined in isolated rat adipocytes. At both 16°C and 37°C, proinsulin was found to have 3% (on a molar basis) the potency of porcine insulin for displacing bound [(125I)TyrA14]-insulin from insulin receptors. Human biosynthetic proinsulin also had 3% of the molar potency of insulin for stimulation of deoxyglucose transport (EC50 = 8.8 ± 0.05 × 10−11 M for insulin and 2.9 ± 0.55 nM for HPro). However, both hormones produced the same maximal effect on glucose transport. In order to determine if the delay in onset and persistence of proinsulin action seen in vivo was due to any differences at the cellular level, the time course of HPro action on glucose transport was determined. Biologically equivalent submaximal concentrations of insulin (0.166 nM) and HPro (4.44 nM) gave identical time courses for stimulation of deoxyglucose transport at 37°C with half-maximal effects at 4 min and full effects by 30 min. Maximally stimulating concentrations of insulin (1.66 nM) and HPro (22.2 nM) also had superimposable time courses. Deactivation of stimulated glucose transport was determined by incubating equivalent concentrations of insulin (0.166 and 1.66 nM) and HPro (4.44 and 22.2 nM) until full stimulation was achieved, washing cells free of unbound hormone, and initiating dissociation and deactivation by resuspension in hormone-free buffer. Both the absolute activities of transport and rates of deactivation were the same for insulin and HPro. At the submaximal concentrations, 50% of the hormones' effects were lost by 20 min, while 50 min was required after maximal stimulation for 50% deactivation. Therefore, the activation and deactivation kinetics of HPro were no different at the cellular level than for insulin;the delayed onset and prolonged persistence of action in vivo may be due to differences in in vivo pharmacokinetic and/or metabolism.