bluuebunny/crossref_metadata_2025 huggingface dataset:
Staphylococcal Enterotoxin-Activated Spleen Cells Passively Transfer Diabetes in BB/Wor Rat
Authors: Ellerman Karen E , Like Arthur A
Published: September 2013

BB/Wor rats develop spontaneous autoimmune diabetes similar to human insulin-dependent diabetes mellitus. A T-cell–mediated pathogenesis for BB/Wor diabetes is indicated because disease is prevented by neonatal or adult thymectomy and treatment of diabetes-prone rats with monoclonal antibodies directed against CD5 or CD8 T-cell surface markers. Disease can be adoptively transferred with injections of concanavalin A–activated spleen cells from either acutely diabetic or RT6.1 T-cell–depleted diabetes-resistant BB/Wor rats. We used microbial superantigens to stimulate spleen cells from RT6.1 T-cell–depleted diabetes-resistant rats and demonstrated that such cells activated with staphylococcal enterotoxins (SEs) can also transfer diabetes. The diabetogenic effector T cells are readily activated by SEA, SEC3, and SEE, whereas SEB- and SEC2-activated cells are far less effective in the adoptive transfer of diabetes. These results demonstrate that microbial superantigens are capable of activating self-reactive and diabetes-inducing T cells in vitro in the BB/Wor rat. Ubiquitous microorganisms may be the environmental trigger for autoimmunity in susceptible individuals.
Effect of Niceritrol on Streptozocin-Induced Diabetic Neuropathy in Rats
Authors: Hotta Nigishi , Kakuta Hironobu , Fukasawa Hideo , Koh Naoki , Sakakibara Fumihiko , Komori Hiraku , Sakamoto Nobuo
Published: September 2013

Niceritrol, a drug with peripheral tissue vasodilatory and serum lipid-lowering activity, was administered for 2 mo to rats with streptozocin-induced diabetes. Physiological and biochemical studies were subsequently conducted on rat nerve tissue. A markedly lower value of ∼ 47% in sciatic nerve blood flow (SNBF) was detected in an untreated diabetic (DC) group than in a nondiabetic control group (CC). A significant delay in caudal motor nerve conduction velocity (MNCV) and significantly higher glucose, sorbitol, and fructose values were observed in the sciatic nerve and serum lipids. In contrast, a niceritrol-treated diabetic (DN) group had significantly higher SNBF, MNCV, and sciatic nerve myo-inositol values and lower serum triglyceride levels than group DC. No differences between these two groups were noted in glucose, sorbitol, and fructose levels in the sciatic nerve, or in cholesterol and glucose in serum. These findings suggest that niceritrol has a clear inhibitory effect on the development of delayed MNCV in the diabetic rat, which may be due to reduced nerve blood flow and/or decreased nerve myo-inositol levels.
Low Plasma Growth Hormone Binding Protein in IDDM
Authors: Mercado Moises , Molitch Mark E , Baumann Gerhard
Published: September 2013

Poorly controlled insulin-dependent diabetes mellitus (IDDM) is associated with elevated basal plasma growth hormone (GH), disproportionally low insulin-like growth factor I (IGF-I) levels, and impaired somatic growth. These derangements in the GH-IGF axis imply a state of GH resistance. The mechanism of GH resistance is unknown; it may involve a defect at the level of the GH receptor, unresponsiveness due to a postreceptor defect in GH action, or both. To investigate a potential receptor involvement, we measured plasma high-affinity GH-binding protein (GHBP), which represents a truncated GH receptor and may reflect GH receptor levels in tissues, in patients with IDDM, patients with non-insulin-dependent diabetes (NIDDM), and nondiabetic control subjects. Patients with IDDM had significantly lower plasma GHBP levels than either patients with NIDDM or nondiabetic control subjects (mean value 18.2 vs. 24.6 and 23.8% GH bound/ml plasma, respectively, P < 0.001). This difference persisted when only lean patients (< 115% ideal body wt) were included in the analysis. Basal plasma GH levels were significantly elevated in IDDM compared with either patients with NIDDM or nondiabetic control subjects (mean 6.9 vs. 2.1 and 2.0 μg/L, respectively, P < 0.001), whereas IFG-I levels were not significantly different in IDDM and NIDDM. No correlations were found between levels of GHBP and HbA1, duration of diabetes, or plasma GH. GHBP and IGF-I levels were significantly correlated in NIDDM but not in IDDM. We conclude that IDDM is associated with low GHBP levels and that GH resistance found in this disorder may be mediated, at least in part, by a decrease in GH receptor levels. Insulinopenia may be the principal reason for GHBP/receptor deficiency.
Developmental Regulation of Amylin and Insulin-Gene Expression in Lean (Fa/Fa) and obese (fa/fa) Zucker rats
Authors: Koranyi Laszlo , Tanizawa Yukio , Penicaud Luc , Atef Nadia , Girard Jean , Permutt M Alan
Published: September 2013

Obese individuals are hyperinsulinemic and insulin resistant. Because amylin is cosecreted with insulin and may contribute to the insulin resistance of obesity, this study tested the hypothesis that insulin and amylin genes are coordinately regulated by obesity and carbohydrate feeding. Insulin and amylin gene expression were measured during the suckling/weaning transition in lean (Fa/Fa) and obese (fa/fa) Zucker rats, a period associated with marked changes in tissue insulin sensitivity. There was a decline in insulin mRNA (−90 ± 15%, P < 0.01) and amylin mRNA (−72 ± 21%, P < 0.01) content in pancreases of lean rats maintained on a high-fat diet from days 15 to 30, probably reflecting the relative increase in exocrine/endocrine development during this neonatal period and the effects of fat feeding. Weaning on high-carbohydrate versus high-fat diets resulted in enhanced expression of both insulin (P < 0.05) and amylin (P < 0.05) mRNAs. In contrast to the decline in pancreatic insulin and amylin mRNA content observed in lean rats, there was an increase in insulin mRNA (421.3 ± 57.5%, P < 0.05) and no change in amylin mRNA in obese rats maintained on a high-fat diet from days 15 to 30. There was no enhancement of insulin or amylin gene expression in obese rats with high carbohydrate relative to high-fat feeding, perhaps reflecting maximum rates of transcription in these obese insulin-resistant rats. Direct comparisons of insulin and amylin mRNA content between lean and obese rats revealed no differences at days 15–22 but enhanced expression of both mRNA types in obese rats by day 30, whether weaned on high-fat (P < 0.01) or high-carbohydrate (P < 0.05) diets. There was a significant correlation between pancreatic content of insulin and amylin mRNA (r = 0.749, P = <0.001) for all of the rats and nutritional conditions studied. These studies show enhanced expression of insulin and amylin genes with carbohydrate feeding and obesity and suggest coordinate expression of the genes that encode these two copackaged and secreted peptides.
Abnormal myoInositol Influx in Human Leucocytes in Diabetes but not Specifically in Diabetic Neuropathy
Authors: Simmons David , Ng Leong L , Bomford Jacqui
Published: September 2013

Abnormal myoinositol metabolism has been implicated as a contributor to the development of diabetic neuropathy. Furthermore, in vitro glucose inhibits animal and human myoinositol transporters. To investigate whether myoinositol transport is abnormal in diabetic subjects with and without neuropathy, we used a triple-isotope technique to measure [14C]myoinositol uptake in leucocytes from 23 insulin-dependent diabetic subjects and 13 matched nondiabetic subjects. All subjects with diabetes underwent neurophysiological studies, and subjects without neuropathy were compared with those with various degrees of neuropathy. The relationship between glycemia and flux was also studied. Diabetic subjects had similar intracellular and plasma myoinositol concentrations but had higher rates of uptake of myoinositol over the extracellular concentrations of myoinositol studied. Although the derived Km, Vmax, and passive components were not significantly different, the Vmax:Km ratio was significantly higher in diabetic subjects compared with nondiabetic subjects (0.25 [0.17–0.32] vs. 0.16 [0.13–0.19], respectively (P = 0.006). In diabetic subjects, the rate of myoinositol uptake correlated with HbA1c, particularly at 3 μM extracellular myoinositol where active uptake was a high proportion of the total influx (P < 0.005). No difference in myoinositol uptake was found among diabetic subjects with various degrees of neuropathy. We conclude that although myoinositol transport is abnormal in diabetes, it is not specifically abnormal in diabetic neuropathy. Prolonged hyperglycemia is associated with higher myoinositol flux.
Glucokinase Gene is Genetic Marker for NIDDM in American Blacks
Authors: Chiu Ken C , Province Michael A , Permutt M Alan
Published: September 2013

Glucokinase (ATP:d-glucose-6-phosphotransferase), expressed exclusively in liver and pancreatic islet β-cells, catalyzes the first step of glycolysis and acts as glucose sensor and metabolic signal generator in these tissues. The enzyme plays a key role in glucose homeostasis and as such is an excellent candidate for inherited defects predisposing to non-insulin-dependent diabetes mellitus (NIDDM). A compound-imperfect dinucleotide (CA)n repeat element was found ∼10-kb 3′ of the human glucokinase gene on chromosome 7p, which revealed polymorphism with alleles differing in size by 2–15 nucleotides in unrelated individuals. A polymerase chain reaction assay was developed, and genomic DNA from 275 biologically unrelated American black individuals was typed for glucokinase alleles. The differences in allelic frequencies between individuals with NIDDM and nondiabetic individuals were compared. After typing 112 diabetic and 163 nondiabetic subjects, we found five different-sized alleles, with Z defined as the most common allele, Z + 2, Z + 4, Z + 10, and Z − 15. The Z allele was more common in nondiabetic subjects than in diabetic patients (60.4 vs. 49.6%, P = 0.012). The Z + 4 allele was more common in diabetic patients than in nondiabetic subjects (20.1 vs. 12.0%, P = 0.009). After adjusting for age, sex, and body mass index, the Z + 4 allele continued to have a positive association with NIDDM (P = 0.0018), and the Z allele had a negative association with NIDDM (P = 0.0334). The Z + 4 allele, transmitted as an autosomal dominant trait, appeared to be the most significant one at this locus. No difference was found in the clinical characteristics between the diabetic patients with or without the Z + 4 allele, after adjusting for multiple comparisons. These results indicate that the dinucleotide (CA)n repeat polymorphism at the glucokinase locus is a genetic marker for NIDDM in American blacks. We estimate that the presence of at least one Z + 4 allele increases the odds of NIDDM in this racial group by 2.85 times for the same age, sex, and body mass index combination.
Enhanced Glucose Tolerance in Spontaneously Hypertensive Rats: Pancreatic β-Cell Hyperfunction With Normal Insulin Sensitivity
Authors: Buchanan Thomas A , Youn Jang H , Campese Vito M , Sipos George F
Published: September 2013

We used intravenous glucose tolerance tests in vivo and 3-O-methylglucose transport into skeletal muscle in vitro to assess glucose tolerance, pancreatic β-cell function, and insulin action in 9- to 11-wk-old spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar Kyoto rats (WKY). Body weight was slightly higher in the WKY (P < 0.001), while blood pressure was elevated in the SHR (P < 0.001). Insulin responses to intravenous glucose after 4 or 12 h of fasting in SHR were 2–3 times the responses of WKY rats (P < 0.001). The greater insulin responses in SHR were associated with accelerated glucose disappearance P < 0.001 vs. WKY rats). A direct correlation (r = 0.49, P < 0.05) between the peak plasma insulin responses to glucose and Kg values in SHR suggested that the exaggerated insulin responses contributed to the accelerated glucose disappearance in that group. 3-O-methylglucose transport rates into epitrochlearis muscles in vitro did not differ significantly between SHR and WKY groups in the absence of insulin (P < 0.2) or in the presence of insulin at physiological (600 pM, P > 0.4) or pharmacological (120,000 pM, P > 0.9) concentrations. Thus, compared with WKY rats, SHR had exaggerated insulin responses to glucose, similar insulin-mediated glucose transport into skeletal muscle, and enhanced glucose tolerance. Our findings indicate that young, hypertensive SHR have hyperfunction of pancreatic β-cells that is unrelated to insulin resistance. The resultant nutrient-stimulated hyperinsulinemia could play a role in the development or maintenance of elevated blood pressure in SHR.
An Explanation for the Neutral Effect of DR2 on IDDM Susceptibility in Central Italy
Authors: Sorrentino Rosa , De Grazia Ugo , Buzzetti Raffaella , Nistico Lorenza , Iannicola Carlo , Costanzi Sandro , Tosi Roberto
Published: September 2013

Susceptibility to IDDM is strongly associated with HLA. Some HLA allelic combinations (haplotypes) can be found in most patients, whereas other haplotypes are encountered only rarely. It has been proposed that this difference in susceptibility depends on the absence (in the DR3 and DR4 haplotypes) or the presence (in the DR2 haplotype) of Asp57 in the DQ β-chain. Data on southern European populations challenge this hypothesis because the DR2 haplotype has not been associated negatively with IDDM, as reported in northern European populations. This study on a selected panel of DR2-positive Italian IDDM patients shows that 19 of 21 (90.5%) DR2 haplotypes possess a non-Asp57 DQB allele. Moreover, the same non-Asp57 subtype has a comparatively high frequency (9/28, or 32.1%, DR2 haplotypes) also in the DR2-positive healthy Italian population. The difference between patients and control subjects is significant (xP < 0.0001). This is the largest series of DR2-positive patients analyzed so far. Comparison with cumulated data in various white populations shows a distinct northern European-to-southern European gradient. Toward southern Europe, the relative frequency of the non-Asp57 DR2 subtype increases. Concomitantly, the apparent protective effect of the DR2 haplotype disappears. Therefore, the observed differences in DR2-IDDM association in white populations can be explained adequately by the Asp57 hypothesis, which this study's data strongly support.
Somatic Gene Therapy for Diabetes With an Immunological Safety System for Complete Removal of Transplanted Cells
Authors: Kawakami Yasushi , Yamaoka Takashi , Hirochika Rei , Yamashita Kamejiro , Itakura Mitsuo , Nakauchi Hiromitsu
Published: September 2013

To develop somatic gene therapy for diabetes, we studied an animal model with proinsulin-producing fibroblasts with an immunological safety system. Cultured mouse fibroblasts of the Ltk− cell line were transfected first with the efficient human proinsulin expression vector pBMG-Neo-Ins. Initially, 2 × 106 cells with a proinsulin-production rate of 91 ng.24 h−1 · 106 cells−1 were transplanted i.p. into streptozocin-induced diabetic C3H mice. The blood glucose concentrations improved between the first and the 28th day, but the animals died of hypoglycemia between the 29th and 46th days. The proinsulin-producing Ltk− cells were further transfected with a second plasmid, pHEBo-CD8.2, encoding BALB/c mouse T-cell differentiation antigen. The CD8.2 allotype is different from CD8.1 allotype by only one amino acid substitution and should be only slightly antigenic to the recipient C3H mice. Somatic gene therapy with these doubly transfected cells followed by the consecutive administration of a monoclonal antibody to CD8.2 resulted in an initial decrease of blood glucose concentrations followed by the permanent recurrence of hyperglycemia, thus proving the complete removal of the transplanted cells. Cultured fibroblasts were thus proven capable of supplying sufficient proinsulin to lower the blood glucose concentrations in diabetic animals. The immunological safety system with a combination of artificial expression of cell surface antigen and the administration of the specific monoclonal antibody was an effective safety system for somatic gene therapy.
Insulinlike Effects of Zinc Ion in Vitro and in Vivo: Preferential Effects on Desensitized Adipocytes and Induction of Normoglycemia in Streptozocin-Induced Rats
Authors: Shisheva Assia , Gefel Dov , Shechter Yoram
Published: September 2013

The effects of Zn2+ in mimicking insulin in vivo and in vitro are further characterized. Like insulin, Zn2+ stimulated the conversion of [U-14C]-, [1-14C]-, and [6-14C]glucose to lipids in rat adipocytes. Maximum stimulation of lipogenesis was 55–80% of maximum insulin response after preincubation (30 min at 37 degrees C) of adipocytes with ZnCl2 (0.4 mM). Under these conditions, the half-maximum effect was achieved at 0.17 ± 0.02 mM of ZnCl2. Similarly, an insulinlike effect of Zn2+ was observed on the oxidation of glucose by both pathways, glycolytic and hexose monophosphate shunt. In contrast, unlike insulin, Zn2+ did not inhibit lipolysis but rather exhibited a slight lipolytic activity. Also, the effect of Zn2+ on hexose influx did not exceed 14 ± 3% that of insulin. The stimulatory effects of Zn2+ were not related to generation of H2O2. Catalase (100 μg/ml) did not inhibit Zn2+-stimulated glucose oxidation and its incorporation into lipids. Zn2+ had an additive effect on either insulin- or vanadate-stimulated conversion of [1-14C]glucose to fat, and together, the effect was ∼ 140% of the maximum rate of lipogenesis. Chelation of intracellular Zn2+ by the cell-permeable chelator N,N,N′,N′-tetrakis (2-pyridylmethyl)ethylenediamine did not significantly affect the ability of insulin to stimulate lipogenesis. Adipocytes derived from STZ rats were largely refractory to the modulating action of insulin. In contrast, the effect of Zn2+ on lipogenesis in these cells was more pronounced. It was more than fivefold that of the hormone, and the dose-response curve shifted to the left (ED50 = 85 ± 10 μM of ZnCI2).l.p. administration of ZnCI2 (100 mg/kg body wt) to hyperglycemic STZ rats reduced blood glucose levels within 3 h to normal values. Similarly, ZnCI2 administered orally to STZ rats (210 mg/kg body wt) reduced blood glucose concentration as much as 50% 2 h after treatment. We conclude that Zn2+ mimics several actions of insulin, both in vitro and in vivo, by a mechanism unrelated to insulin. The clinical implication of this study is discussed.
A Practical Approach to Identification of Susceptibility Genes for IDDM
Authors: Todd John A , Bain Stephen C
Published: September 2013

Of all the common diseases that have a genetic component, IDDM is probably the most tractable to the experimentalist. Large numbers of nuclear multiplex families are available, which can be stored as permanent cell lines; diagnosis is relatively unambiguous; and a mouse strain, the NOD, spontaneously develops autoimmune IDDM similar to the human disorder. In addition, the resolution and accessibility of the human genome map has been revolutionized by the discovery and widespread application of the PCR, particularly the amplification of short, tandemly repeated segments of DNA called microsatellites, which display high levels of allelic polymorphism. With these reagents, the stage is set for dissection of the genetic factors that control the pathophysiology of IDDM.
Ambulatory Blood Pressure in Type I Diabetes Mellitus: Comparison to Presence of Incipient Nephropathy in Adolescents and Young Adults
Authors: Moore Wayne V , Donaldson David L , Chonko Arnold M , Ideus Patti , Wiegmann Thomas B
Published: September 2013

AMBP measurements were obtained at 20-min intervals during the day and at 60-min intervals during the night in 38 adolescents and young adults (12–25 yr old) with type I diabetes, and in 36 healthy, nondiabetic control subjects of comparable age. The group of patients with elevated AER (>15 μg/min) had higher mean 24-h sBP, dBP, and BPB (defined as the prevalence of systolic readings >130 mm Hg or diastolic readings >85 mm Hg) compared with both the group of patients with type I diabetes and AER<15, and the control group. The normal diurnal variation in BP and BPB was observed in the control group and the group with type I diabetes and AER<15, whereas the nocturnal decrease observed in the group with type I diabetes and AER>15 was not statistically significant. Elevations in AMBP of the patient group with AER>15 were reflected in random BP measurements. Even though the mean random BP measurements of all groups were within the normal range for age, the mean random sBP and dBP of the type I diabetes patients with AER>15 was higher than both the control group and the group with type I diabetes and AER<15. The GFR, determined by the clearance of 99Tc-DTPA, was associated negatively with measures of AMBP and AER in the group with AER>15. The mean 24-h sAMBP, dAMBP, and BPB of the type I diabetes patients with AER<15 were elevated compared with the control group. The mean random sBP of the type I patients with AER<15 was not significantly different from the control group, whereas the mean random dBP of this group was significantly greater than the control group. Significant overlap in the BPs and BPBs occurred among the groups, but the mean 24-h sBP and BPBs were above the 90th percentile for control subjects in most type I diabetes patients with AER<15 and in ∼50% of type I diabetes patients with AER<15. The three groups separated across the age range (12–25 yr old) for the different measures of AMBP. We conclude that AMBP measurement is useful in detecting abnormalities in BP that are not apparent in random BP measurement in patients with onset of type I diabetes before puberty and no evidence of early diabetic nephropathy. These findings may be important in identifying individuals who either are susceptible to the development of diabetic nephropathy or have early renovascular dysfunction not apparent in AER>15. AMBP measurement may be useful in monitoring interventions designed to prevent or delay the development of diabetic nephropathy.
An ELISA for Antibodies to Recombinant Glutamic Acid Decarboxylase in IDDM
Authors: Deaizpurua Henry J , Harrison Leonard C , Cram David S
Published: September 2013

To detect serum antibodies to GAD in subjects with IDDM, three recombinant mBGAD 67 peptides encompassing the full-length protein were used in an ELISA. In this study 7 of 9 (78%) preclinical IDDM subjects (ICA+ first-degree relatives of a person with IDDM) and 6 of 13 (46%) recent-onset IDDM subjects, but no subjects with Graves' disease (n = 10) or scleroderma (n = 10), nor healthy nondiabetic control subjects (n = 10) had antibodies that reacted with one or more of the recombinant mBGAD peptides. We found no preferential reactivity with any recombinant peptide. Although only 3 preclinical subjects and 1 recent-onset subject had antibodies to all three mBGAD peptides, the results indicate that mBGAD 67 contains at least three B-cell autoepitopes. Compared with an immunoprecipitation assay of native human brain GAD, the ELISA detected 5 of 6 (83%) preclinical and 6 of 6 (100%) recent-onset IDDM subjects. The ELISA should facilitate screening to evaluate the role of autoimmunity to GAD in the development of IDDM.
Lilly Lecture: Syndromes of Insulin Resistance: From Patient to Gene and Back Again
Authors: Flier Jeffrey S
Published: September 2013

The syndromes of insulin resistance are a group of clinically diverse disorders, and our understanding of their molecular pathogenesis has advanced in parallel with our understanding of the structure of the insulin receptor and the mechanism of insulin action. The most straightforward progress has related to defining the role of both anti-receptor antibodies and mutations in the insulin receptor gene in causing these disorders. Despite this progress, the cause of severe target cell resistance in patients without defects in the receptor locus remains unknown, and we are limited in our ability to relate specific molecular defects in insulin signalling to in vivo phenotypes, such as those relating to growth and development and function of adipose tissue and muscle. Answers to these questions may ultimately be explained by the existence of multiple species of insulin receptors expressed in different tissues, brought about by alternative splicing and receptor hybrids, and by divergent pathways of insulin signalling with different consequences for specific tissues. The possibility that the insulin receptor and GLUT4 may be candidate genes for inherited insulin resistance in NIDDM has been addressed with the aid of genetic screening techniques such as SSCP. Currently, the loci have not been implicated in studies in most patients. Transgenic methodologies will be powerful tools for pursuit of unanswered questions in the field of insulin resistance in coming years.
Distribution of Type II Diabetes in Nuclear Families
Authors: Cook Joanne T E , Hattersley Andrew T , Levy Jonathan C , Patel Pushpa , Wainscoat James S , Derek T , Hockaday R , Turner Robert C
Published: September 2013

Type II diabetes has a substantial genetic component, but the mode of inheritance and the molecular basis of this inheritance are uncertain. This study documents the familial distribution of the disease in the parents and siblings of a consecutive series of type II diabetic subjects. We studied 66 first-degree relatives of 20 white subjects with type II diabetes and both parents alive. They were tested with a continuous infusion of glucose (5 mg · kg IBW−1 · min−1) (n = 49) or FPG and hemoglobin A1c (n = 17). Seven probands had neither parent affected with diabetes or IGT, 10 had one parent affected (6 with diabetes and 4 with IGT), and 3 had both parents affected. The probands with affected and those with unaffected parents were phenotypically similar. These findings indicate that a sizable subgroup of type II diabetic subjects may have neither parent affected with a demonstrable abnormality of glucose tolerance. The assumption of autosomal dominance with complete penetrance is not supported, although it remains possible that a dominant gene of low penetrance may play a role in some pedigrees. Polygenic inheritance would appear likely, and genetic heterogeneity may occur. The inheritance of diabetic traits from phenotypically normal parents needs to be considered in the analysis of genetic linkage with type II diabetes.
Effect of Hypoxia on Insulin Secretion by Isolated Rat and Canine Islets of Langerhans
Authors: Dionne Keith E , Colton Clark K , Lyarmush Martin
Published: September 2013

The effect of pO2s reduced below physiological levels on GSIR by isolated islets of Langerhans was investigated with a microperifusion apparatus that provided control of pO2 and rapid dynamic response. Second-phase insulin secretion was reduced substantially by hypoxia. The response to lower pO2 was rapid and reversible. Although the steady, normoxic (pO2 = 142 mmHg) second-phase secretion rate varied widely from one islet preparation to another, the ratio of Sx to S142 for each preparation could be represented by a single curve that exhibited a continuous reduction with decreasing pO2. For rat islets perifused 1 day after isolation, the secretion rate was nearly 100% of the normoxic value at a pO2 of 60 mmHg, 50% at 27 mmHg (P50, the pO2 at which the S142 is reduced by 50%), and ∼2% at 5 mmHg. Oxygen sensitivity of second-phase secretion rate declined after 1 wk of in vitro culture: P50 was 13 mmHg after 1 wk and remained at 10 mmHg after 2–5 wk of culture. Canine islets exhibited a P50 of 16 mmHg after 1 wk of culture. The reduction in insulin secretion is thought to be associated with the existence of pO2 gradients outside and inside the isolated islets, resulting in exposure of islet cells to low pO2 levels that decrease radially from the periphery to the core. We hypothesize that the effect of low pO2 on S is manifested through depletion of the energy stores of the β-cells. The effect of hypoxia on S may be an important factor in some in vitro secretion studies and may play a critical role in the effectiveness of transplanted islets before their revascularization and of immunoisolated islet implantation devices.
Increase in Simultaneous Coexpression of Naive and Memory Lymphocyte Markers at Diagnosis of IDDM
Authors: Smerdon Rebecca A , Peakman Mark , Hussain Munther J , Alviggi Lorenzo , Watkins Peter J , Leslie R David G , Vergani Diego
Published: September 2013

The monoclonal antibodies 2H4 (antl-CD45RA) and UCHL1 (antl-CD45RO) were used to subdivide the CD4 and CD8 T-cell subsets into naive and memory cells. The peripheral blood lymphocytes of 34 patients with recent-onset IDDM, 21 patients with long-standing IDDM, and healthy control subjects of similar age and sex were analyzed by a three-color immunofluorescence technique. CD4 and CD8 lymphocytes expressed the CD45 isoforms alone (CD45RA+ or CD45RO+) or in combination (CD45RA+RO+). Simultaneous coexpression of both CD45RA and CD45RO (CD45RA+RO+) on CD4 and CD8 lymphocytes in patients with recent-onset IDDM was higher than in control subjects (P < 0.001). The proportion of CD4 lymphocytes expressing CD45RA alone (CD45RA+RO−) was similar in these groups, but the percentage of CD8 lymphocytes that were CD45RA+RO− was significantly higher in the patients with recent-onset IDDM (P < 0.05). The result of these changes is a significant increase in expression of naive phenotypes (CD45RA+ and CD45RA+RO+) on CD4 and CD8 lymphocytes in recent-onset IDDM (P < 0.005 and P < 0.0001). In long-standing IDDM, total CD45RA+ expression on CD4 and CD8 lymphocytes was reduced compared with control subjects (P < 0.05) as a result of a tendency of CD45RA+RO+ and CD45RA+RO+ subsets to be lower. This increase in total naive (CD45RA+) lymphocytes and in coexpression of naive (CD45RA) and memory (CD45RO) markers on CD4 and CD8 lymphocytes subsets In patients with recent-onset IDDM suggests that abnormal regulation of T-cell activation andmaturation is important in the pathogenesis of the disease.
Endothelium-Dependent Vascular Relaxation in Patients With Type I Diabetes
Authors: Smits Paul , Kapma Jan-Auke , Jacobs Marie-Cécile , Lutterman Jos , Then Theo
Published: September 2013

The endothelium plays an important role in the regulation of vascular tone. Although animal data show evidence for an impaired endothelium-dependent vasodilation in diabetes, human in vivo data are scarce. We investigated 11 type I diabetic patients and 11 matched healthy control subjects. The diabetic patients were selected on their relatively poor metabolic regulation (HbA1c > 8.5%), but none showed signs of microvascular complications. In all subjects, we recorded the forearm vasodilator responses to three different stimuli: 1) 5 min of forearm ischemia to obtain a maximal vasodilator response; 2) infusion of MCh into the brachial artery (dosages: 0.03–0.3–1.0 μg · min−1 · 100 ml−1 forearm volume) to evaluate endothelium-dependent vasodilation; and 3) intra-arterial infusion of SNP (dosages: 0.06–0.2–0.6 ng · min−1 · 100 ml−1) to evaluate endotheliumindependent vasodiiation. The diabetic patients had their usual subcutaneous insulin dose and breakfast 90 min before the start of the test. Baseline levels of BP and FBF were similar in both groups. The PORH response was similar in both groups, with a percentage fall in FVR of 92 ± 1% in diabetic patients and 94 ± 1% in control subjects. In the control subjects, MCh infusions exerted a dose-dependent vasodilator response with a maximal fall in the FVR of 90 ± 2%. The highest dose of SNP induced a fall in FVR of 81 ± 6% in this group. In diabetic patients, thepercentage decrements in FVR during the several dosages of MCh and SNP were similar when compared with the control group. We conclude that chronic hyperglycemia, as occurred in our patients with uncomplicated diabetes mellitus, does not impair endothelium-dependent vasodilation in vivo.
Normal Proinsulin Responses to Glucose in Mild Type II Subjects With Subnormal Insulin Response
Authors: Levy Jonathan C , Clark Penelope M , Hales C Nicholas , Turner Robert C
Published: September 2013

IPI, 32–33 SPI, and insulin were measured by specific assays and related to plasma glucose and BMI in diet-treated type II diabetic subjects (FPG 7.3 ± 1.8 mM) and nondiabetic control subjects, both fasting and during a 12-mM hyperglycemic clamp. In both groups, BMI correlated with fasting plasma insulin (rs = 0.76, P < 0.001 and 0.50, P < 0.01, respectively) and IPI (rs = 0.49, P = 0.03 and rs = 0.69, P < 0.001, respectively). Accounting for obesity, fasting plasma insulin was subnormal in diabetic subjects (58% of control group, 1 SD range, 49–68%), but did not correlate with FPG. In contrast, fasting plasma IPI correlated with FPG in the diabetic patients (rs = 0.47, P < 0.05). In all subjects, 64% of the variance in plasma IPI was explained by BMI and FPG. Fasting 32–33 SPI was similar in the two groups. In response to a hyperglycemic clamp, the diabetic subjects had subnormal insulin concentrations (geometric means 71 and 214 pM, P < 0.001), but normal IPI concentrations (11.6 and 14.2 pM, respectively). Reduction of 32–33 SPI concentrations in diabetic subjects was intermediate (7.3 and 13.2 pM, P < 0.05). In diabetic subjects both fasting and clamp responses were subnormal for insulin but apparently normal for IPI. The major defect in pancreatic function is an impaired insulin response to glucose, and this, rather than an increase in proinsulin secretion, gives rise to the relative increase in proinsulin.
Picotamide, a Dual TXB Synthetase Inhibitor and TXB Receptor Antagonist, Reduces Exercise-Induced Albuminuria in Microalbuminuric Patients With NIDDM
Authors: Giustina Andrea , Bossoni Simonetta , Cimino Antonino , Comini M Teresa , Gazzoli Nadia , Leproux G Battista , Wehrenberg William B , Romanelli Giuseppe , Giustina Gianni
Published: September 2013

We investigated the short-term effect of the TXB inhibitor picotamide on albuminuria induced by exercise in 15 microalbuminuric (i.e., with UAE at rest between 20 and 200 μg/min) type II diabetic patients (12 men and 3 women, age 56 ± 2, BMI 28 ± 1 kg/m2) and in six normal age-matched control subjects. The diabetic subjects performed five submaximal exercise tests (90% of theoretical heart rate) on a cycle ergometer: the first two under basal conditions; the third and fifth after subjects had received picotamide (900 mg/day) or placebo (3 tablets/day) for 10 days; the fourth exercise always was performed after 10 days of wash-out. Control subjects performed two exercises: the first in baseline conditions and the second after 10 days of picotamide administration (900 mg/day). When diabetic patients were untreated, a significant (P < 0.05) increase in UAE with respect to baseline levels was observed immediately after and 1 h after the exercise test. After picotamide administration, UAE significantly decreased (P < 0.05) immediately after and 1 h after exercise, as compared with diabetic patients given a placebo. In normal subjects, exercise was followed by a slight increase in UAE, which was not significantly affected by picotamide administration. Our results show that short-term administration of picotamide is associated with a reduction in UAE after exercise in type II diabetes patients with microalbuminuria while at rest. Picotamide, a TXB synthetase and receptor inhibitor, may decrease exercise-induced albuminuria in diabetic patients through a reduction in circulating TXB levels andinhibition of TXB action, which in turn may act by lowering glomerular capillary hydraulic pressure.
Calcium Is Essential in Normalizing Intolerance to Glucose That Accompanies Vitamin D Depletion In Vivo
Authors: Beaulieu Christine , Kestekian Rena , Havrankova Jana , Gascon-Barré Marielle
Published: September 2013

Vitamin D is essential for normal insulin secretion in vivo and in vitro. The differential effect of calcium and of the vitamin D endocrine system in the insulin response to secretagogues is still a subject of debate. To study the roles of calcium and the vitamin D system in the in v vitamin D depletion and hypocalcemia or vitamin D depletion supplemented with calcium alone for 3, 7, or 14 days, vitamin D3 (6.5 nmol/day × 7 days), or 1,25(OH)2D3 (28 pmol/day × 7 days). Serum calcium was 1.28 ± 0.04 mM in hypocalcemic vitamin D-depleted rats, 1.47 ± 0.06 (NS), 1.8 ± 0.2 (P <0.0002), and 2.04 ± 0.07 (P < 0.0001) mM after 3, 7, or 14 days, respectively, of calcium supplementation; vitamin D3- or 1,25(OH)2D3- supplemented animals had serum calcium of 2.61 ± 0.04 or 2.48 ± 0.05 mM (P 67 < 0.0001 vs. hypocalcemic vitamin D-depleted rats). Rats with hypocalcemia and vitamin D depletion had significantly higher glucose concentrations (P < 0.0005) and lower insulin response during GTT than all other groups (P < 0.001). Differences in insulin sensitivity could not account for differences in response because exogenous insulin administration led to a similar drop in glucose concentrations in all groups, with the nadir averaging 51.7 ± 2.6% of initial values. To distinguish between calcium and the vitamin D system in the GTT response, rats were treated with a nonhypercalcemic analogue of 1,25(OH)2D3, OCT (28 pmol/day × 4-7days) with or without dietary calcium. Serum calcium was 1.23 ± 0.04 vs. 2.09 ± 0.02 mM in the absence or presence of dietary calcium (P < 0.0001), but normalization of GTT only happened in the presence of calcium. A time course of the calcium effect in vitamin D-depleted rats indicated that 7 days of high dietary calcium intake was needed to normalize GTT, with a significant correlation coefficient being observed between serum calcium and the maximum insulin response (r = 0.5172, P < 0.004). Our data indicate that vitamin D depletion with hypocalcemia is associated with normal insulin sensitivity but glucose intolerance caused by inadequate insulin secretion in response to glucose. Calcium alone contributes in normalizing GTT, whereas the 1,25(OH)2D3 analogue OCT is unable to normalize GTT at a dose equimolar to that of 1,25(OH)2D3 in the absence of calcium, suggesting that hypocalcemia predominates over vitamin D depletion in the glucose intolerance of vitamin D deficiency.
Galanin-Stimulated High-Affinity GTPase Activity in Plasma Membranes From RINm5F Cells
Authors: Skoglund G , Bliss C R , Sharp G W G
Published: September 2013

GTPase activity was studied in plasma membranes purified from the clonal β-cell line RINm5F. GTPase activities were identified as two broad classes with high or low affinity for GTP. The low-affinity GTPase activity had a Km >60 μM. In contrast, the high-affinity activity had a Km of 225 nM. Only the high-affinity activity was stimulated by galanin. The stimulated activity had a higher Km (448 nM) and Vmax (75 pmol PI · min−1 · mg−1 protein) compared with the basal. This does not necessarily reflect a complex mechanism of stimulation. Rather, it may reflect that basal activity most likely results from multiple GTPases, whereas the stimulated activity probably reflects one or two specific GTPases. Galanin stimulated the high-affinity GTPase, over the concentration range in which it inhibits stimulated insulin secretion, to a maximal rate 80% greater than the basal rate. The EC50 was 5 nM. Murine and porcine galanin had similar potencies and intrinsic activities on the GTPase. Treatment of the RINmSF cells with PTX before making membranes completely eliminated the stimulatory effect of galanin. Thus, galanin stimulates PTX-sensitive GTPase activity in RINm5F cell membranes in a manner consistent with receptor activation.
STZ-Induced Diabetes Results in Decreased Activity of Glomerular Cathepsin and Metalloprotease in Rats
Authors: Reckelhoff Jane F , Tygart Vicky L , Mitias Michel M , Walcott Jamie L
Published: September 2013

IDDM in humans and STZ-induced diabetes in rats are both characterized in the early phase of the disease by glomerular hypertrophy; and, in the chronic phase of the disease, by mesangial expansion and glomerular basement membrane thickening. Decreases in glomerular intracellular protein degradation rates in diabetic individuals could contribute to the glomerular hypertrophy by allowing a build-up of cellular protein. Decreases in extracellular protease activity could contribute to the build-up of matrix protein in the mesangium and glomerular basement membrane. In this study, the levels of lysosomal cathepsin activities and glomerular metalloprotease activities were measured in isolated glomerular homogenates from STZ-induced diabetic rats at 4 days and 5 wk after administration of the drug. Some of the rats in the 5-wk study were treated with daily insulin; others were untreated. After 4 days of diabetes, cathepsin B and L activities were decreased by 15–45% when correlated with the levels of glomerular protein or DNA. Glomerular metalloprotease activity was decreased by 75% in the diabetic rats when compared with controls. After 5 wk of diabetes, cathepsin activities either were unchanged (for cathepsin B and L together or cathepsin S) or increased (cathepsin B alone) in insulin-treated diabetic rats, and continued to be decreased in untreated diabetic rats. A 40–50% decrease in glomerular metalloprotease activity continued in both diabetic groups. These data strongly suggest that decreases in the lysosomal cathepsin activities may contribute to IDDM-induced glomerular cellular hypertrophy. The data further indicate that a decrease in glomerular metalloprotease activity may contribute to diabetes-induced mesangial expansion and glomerular basement membrane thickening. The decrease in glomerular metalloprotease activity may be attributable to a decrease in metalloprotease synthesis or to an increase in endogenous tissue inhibitor of metalloprotease.
Apolipoprotein E Polymorphism Modifies Relation of Hyperinsulinemia to Hypertriglyceridemia
Authors: Després Jean-Pierre , Verdon Marie-France , Moorjani Sital , Pouliot Marie-Christine , Nadeau André , Bouchard Claude , Tremblay Angelo , Lupien Paul J
Published: September 2013

The effect of apolipoprotein E polymorphism on the established relationships between glucose tolerance, plasma insulin levels, and plasma lipoprotein concentrations were investigated in a sample of women defined on the basis of apolipoprotein E phenotypes. In women with the apolipoprotein E ε2 allele (n = 22), fasting plasma insulin and glucose and insulin areas under the curve measured during an oral glucose tolerance test were positively correlated with plasma triglyceride levels (0.48 ≤ r ≤ 0.70; P < 0.05). In this group, very-low-density lipoprotein cholesterol and very-low-density lipoprotein triglyceride concentrations were positively correlated with fasting insulin levels, the insulin area, and with the ratio of insulin area to glucose area. In women (n = 24) homozygous for the apolipoprotein E ε3 allele (the most common allele), essentially similar associations were found. In contrast, in women (n = 17) with the apolipoprotein E ε4 allele, no association was found between glucose tolerance, fasting and postglucose plasma insulin levels, and plasma lipid and lipoprotein levels. These results suggest that apolipoprotein E polymorphism substantially modifies the associations between glucose tolerance, plasma insulin levels, and plasma lipoprotein concentrations. Additional analysis of the data revealed that apolipoprotein E polymorphism did not alter the relationships between body fat distribution and fasting insulin and postglucose insulin levels, but no correlation was observed between fatness indexes and glucose tolerance among apolipoprotein E ε2 carriers. Therefore, the mechanisms by which apolipoprotein E polymorphism modifies plasma lipoprotein levels in a hyperinsulinemic state is not by altering the relationship of abdominal obesity to hyperinsulinemia but more likely by modifying the metabolic fate of triglyceride-rich lipoproteins in hyperinsulinemic, insulin-resistant subjects.
Altered Distribution of Insulin Between Intravascular and Interstitial Compartments in STZ-Induced Diabetic Rats
Authors: Bryer-Ash Michael
Published: September 2013

These studies were undertaken to determine the distribution of insulin between the intravascular and interstitial compartments in 19 nondiabetic and 16 high-dose (60 mg/kg) STZ-induced diabetic rats. Anesthetized male rats underwent cannulation of the thoracic lymph duct with continuous collection of lymph by passive drainage; 90-min hyperinsulinemic (0, 14, 28, or 42 pmol · kg−1 · min−1) glucose clamps were performed with serum glucose held at the preinfusion level. Integrated lymph samples were collected, with serum collection at the midpoint. Before insulin infusion, insulin levels in lymph as a percentage of levels in serum were higher in the diabetic rats (lymph = 103 ± 8% of 52 matched serum values, mean ± SE) compared with nondiabetic rats (lymph = 83 ± 3% of serum; n = 84, P < 0.008). Under steady-state conditions during insulin infusion (66-90 min), lymph insulin as a percentage of serum insulin decreased significantly in nondiabetic animals (range 53-62% in all insulin-infused groups, vs. 94% in the absence of insulin infusion, P < 0.0001). However, in the diabetic animals, the proportion was similar in the presence or absence of infused insulin (range 57–63% in insulin-infused groups vs. 70% in the absence of infused insulin, P = NS). Lymph flow rate was significantly higher in diabetic than nondiabetic rats (37.7 ± 7.2 vs. 17.9 ± 1.5 microliters/min [mean ± SE], P < 0.02). Distribution of [14C]inulin was uniform between the two compartments in all animals. In nondiabetic rats, correlation of lymph and serum levels of insulin with hepatic glucose output was equal(r = −0.86 and −0.85 for serum and lymph insulin, respectively) and as was the case for peripheral glucose disposal, r = 0.75 for serum, and r = 0.72 for lymph. Estimated clearance of insulin from serum to lymph was 100% higher in the diabetic rats (22.9 vs.12.7 µl/min). The mechanism is unclear but may represent increased transcapillary transport of insulin, adaptive to insulin deficiency.
Induction of Donor-Specific Tolerance to Rat Islet Allografts by Intrathymic Inoculation of Solubilized Spleen Cell Membrane Antigens
Authors: Qian Tie , Schachner Robert , Brendel Mathias , Kong Shen Shen , Alejandro Rodolfo
Published: September 2013

The development of strategies that will allow permanent survival of islet allografts without continuous host immunosuppression continues to be the most important goal in the field of pancreatic islet cell transplantation. In our study, we demonstrated that intrathymic inoculation of allogeneic spleen cell membrane antigens with a single dose of anti-lymphocyte serum induces an unresponsive state that permits survival of a subsequent pancreatic islet allograft to an extrathymic site (renal subcapsular space). This effect is donor specific and cannot be reproduced by the intravenous injection of spleen cell membrane antigens. Our results offer a potential approach for establishing donor-specific allograft acceptance in adult recipients.