bluuebunny/crossref_metadata_2025 huggingface dataset:
Glucagon-Like Peptides
Authors: Drucker Daniel J
Published: September 2013

Proglucagon contains the sequence of two glucagonlike peptides, GLP-1 and GLP-2, secreted from enteroendocrine cells of the small and large intestine. GLP-1 lowers blood glucose in both NIDDM and IDDM patients and may be therapeutically useful for treatment of patients with diabetes. GLP-1 regulates blood glucose via stimulation of glucose-dependent insulin secretion, inhibition of gastric emptying, and inhibition of glucagon secretion. GLP-1 may also regulate glycogen synthesis in adipose tissue and muscle; however, the mechanism for these peripheral effects remains unclear. GLP-1 is produced in the brain, and intracerebroventricular GLP-1 in rodents is a potent inhibitor of food and water intake. The short duration of action of GLP-1 may be accounted for in part by the enzyme dipeptidyl peptidase 4 (DPP-IV), which cleaves GLP-1 at the NH2-terminus; hence GLP-1 analogs or the lizard peptide exendin-4 that are resistant to DPP-IV cleavage may be more potent GLP-1 molecules in vivo. GLP-2 has recently been shown to display intestinal growth factor activity in rodents, raising the possibility that GLP-2 may be therapeutically useful for enhancement of mucosal regeneration in patients with intestinal disease. This review discusses recent advances in our understanding of the biological activity of the glucagon-like peptides.
Effects of Leptin on Insulin Secretion From Isolated Rat Pancreatic Islets
Authors: Ookuma Mari , Ookuma Kazuyoshi , York David A
Published: September 2013

Leptin is a hormone secreted by adipocytes as a peripheral metabolic signal for the central regulation of energy homeostasis or the reproductive system. Recent studies demonstrated that leptin receptor mRNA is expressed in pancreatic islets of rodents and that leptin at relatively high doses inhibits glucose-induced insulin secretion from rat islets. However, the physiological mechanism of leptin on insulin secretion has not been identified. In this study, we report that leptin inhibits glucose-induced insulin secretion at lower concentrations ranging from 25 to 50 ng/ml using a static incubation method. A perifusion study revealed that leptin (50 ng/ml) affected the second phase of insulin secretion but not the first phase. Leptin did not affect insulin secretion stimulated by glibenclamide (1 and 5 μmol/l) or forskolin (1 μmol/l). Leptin (50 ng/ml) significantly inhibited insulin secretion induced by the phorbol ester phorbol 12-myristate 13-acetate (TPA) in the presence of Ca2+ but not in the absence of Ca2+. Because TPA is known to activate protein kinase C (PKC), these present results suggest that leptin, at a physiological concentration, suppresses the second phase of insulin secretion by reducing activity of the Ca2+-dependent PKC isoform.
Experimental NIDDM: Development of a New Model in Adult Rats Administered Streptozotocin and Nicotinamide
Authors: Masiello Pellegrino , Broca Christophe , Gross René , Roye Michèle , Manteghetti Michèle , Hillaire-Buys Dominique , Novelli Michela , Ribes Gérard
Published: September 2013

We took advantage of the partial protection exerted by suitable dosages of nicotinamide against the β-cytotoxic effect of streptozotocin (STZ) to create a new experimental diabetic syndrome in adult rats that appears closer to NIDDM than other available animal models with regard to insulin responsiveness to glucose and sulfonylureas. Among the various dosages of nicotinamide tested in 3-month-old Wistar rats (100–350 mg/kg body wt), the dosage of 230 mg/kg, given intraperitoneally 15 min before STZ administration (65 mg/kg i.v.) yielded a maximum of animals with moderate and stable nonfasting hyperglycemia (155 ± 3 vs. 121 ± 3 mg/dl in controls; P < 0.05) and 40% preservation of pancreatic insulin stores. We also evaluated β-cell function both in vitro and in vivo 4–9 weeks after inducing diabetes. In the isolated perfused pancreas, insulin response to glucose elevation (5–11 mmol/l) was clearly present, although significantly reduced with respect to controls (P < 0.01). Moreover, the insulin response to tolbutamide (0.19 mmol/l) was similar to that observed in normal pancreases. Perfused pancreases from diabetic animals also exhibited a striking hypersensitivity to arginine infusion (7 mmol/l). In rats administered STZ plus nicotinamide, intravenous glucose tolerance tests revealed clear abnormalities in glucose tolerance and insulin responsiveness, which were interestingly reversed by tolbutamide administration (40 mg/kg i.v.). In conclusion, this novel NIDDM syndrome with reduced pancreatic insulin stores, which is similar to human NIDDM in that it has a significant response to glucose (although abnormal in kinetics) and preserved sensitivity to tolbutamide, may provide a particularly advantageous tool for pharmacological investigations of new insulinotropic agents.
Coronary Flow Reserve Is Reduced in Young Men With IDDM
Authors: Pitkänen Olli-Pekka , Nuutila Pirjo , Raitakari Olli T , Rönnemaa Tapani , Koskinen Pertti J , Iida Hidehiro , Lehtimäki Terho J , Laine Hanna K , Takala Teemu , Viikari Jorma S A , Knuuti Juhani
Published: September 2013

Disturbances of coronary circulation have been reported in diabetic patients with microvascular complications but without obstructive coronary atherosclerosis. The aim of the present study was to investigate coronary flow reserve in young adult patients with IDDM but without microalbuminuria and diabetic autonomic neuropathy. Coronary flow reserve was determined in 12 nonsmoking male patients with IDDM (age 30.0 ± 6.6 years) and 12 healthy matched volunteers. Groups were similar with respect to blood pressure and serum lipid concentrations, and no subject had a positive family history of coronary heart disease. The patients with IDDM had normal exercise echocardiography and autonomic nervous function tests. Five patients had minimal background retinopathy, and none had microalbuminuria. Positron emission tomography and [15O]H2O were used to measure myocardial blood flow at rest and after dipyridamole administration. The studies were performed during euglycemic hyperinsulinemia (serum insulin ∼70 mU/1). The baseline myocardial blood flow was similar in patients with IDDM and in control subjects (0.84 ± 0.18 vs. 0.88 ± 0.25 ml · g−1 · min−1, NS). The myocardial blood flow during hyperemia was 29% lower in patients with IDDM (3.17 ± 1.57) compared with the control subjects (4.45 ± 1.37 ml · g−1 · min−1 P < 0.05). Consequently, coronary flow reserve (the ratio of flow during hyperemia and at rest) was lower in diabetic patients than in control subjects (3.76 ± 1.69 vs. 5.31 ± 1.86, P < 0.05) and the total coronary resistance during hyperemia was higher in diabetic patients (53.7 ± 31.5) compared with the control subjects (31.4 ± 11.6 mmHg · min · g · ml−1 P < 0.05). The coronary flow reserve was similar in diabetic patients with and without mild background retinopathy. No association was found between the coronary flow reserve and serum lipid or HbAlc values in either group. Coronary flow reserve is impaired in young adult males with IDDM and no or minimal microvascular complications and without any evidence of coronary heart disease. This abnormality cannot be explained by standard coronary heart disease risk factors. The results imply early impairment of coronary vascular reactivity in IDDM patients, which may represent an early precursor of future coronary heart disease or may contribute to the pathogenesis of diabetic cardiomyopathy.
Improved Glucose Tolerance in Zucker Fatty Rats by Oral Administration of the Dipeptidyl Peptidase IV Inhibitor Isoleucine Thiazolidide
Authors: Pederson Raymond A , White Heather A , Schlenzig Dagmar , Pauly Robert P , McIntosh Christopher H S , Demuth Hans-Ulrich
Published: September 2013

The hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide (GLP)-1 act on the pancreas to potentiate glucose-induced insulin secretion (enteroinsular axis). These hormones (incretins) are rapidly hydrolyzed by the circulating enzyme dipeptidyl peptidase IV (DP IV) into biologically inactive NHg-terminally truncated fragments. This study describes the effect of inhibiting endogenous DP IV with a specific DP IV inhibitor, isoleucine thiazolidide (Ile-thiazolidide), on glucose tolerance and insulin secretion in the obese Zucker rat. In initial studies, the specificity of Ile-thiazolidide as an inhibitor of incretin degradation was determined using matrix-assisted laser desorption7sol;ionization-time of flight mass spectrometry. These results showed that inhibiting DP IV activity with Ile-thiazolidide blocked the formation of NH2-terminally truncated GIP and GLP-1. Oral administration of Ile-thiazolidide resulted in rapid inhibition of circulating DP IV levels by 65% in obese and lean Zucker rats. Suppression of DP IV levels enhanced insulin secretion in both phenotypes with the most dramatic effect occurring in obese animals (150% increase in integrated insulin response vs. 27% increase in lean animals). Ile-thiazolidide treatment improved glucose tolerance in both phenotypes and restored glucose tolerance to near-normal levels in obese animals. This was attributed to the glucose-lowering actions of increasing the circulating half-lives of the endogenously released incretins GIP and, particularly, GLP-1. This study suggests that drug manipulation of plasma incretin activity by inhibiting the enzyme DP IV is a valid therapeutic approach for lowering glucose levels in NIDDM and other disorders involving glucose intolerance.
Effect of Physiological Hyperinsulinemia on Blood Flow and Interstitial Glucose Concentration in Human Skeletal Muscle and Adipose Tissue Studied by Microdialysis
Authors: Rosdahl Hans , Lind Lars , Millgård Jonas , Lithell Hans , Ungerstedt Urban , Henriksson Jan
Published: September 2013

The effect of an euglycemic-hyperinsulinemic glucose clamp (94 ± 5 μU/ml) on blood flow and glucose extraction fraction in human skeletal muscle and adipose tissue was investigated. Limb blood flow was measured by venous occlusion pletysmography and tissue blood flow by the microdialysis ethanol technique. Insulin infusion resulted in an increased blood flow in the calf and forearm (64 and 36%, respectively; P < 0.01) but not in the studied muscles of these limbs (ethanol outflow-to-inflow ratio: m. gastrocnemius 0.144 ± 0.009 to 0.140 ± 0.011, NS; m. brachioradialis 0.159 ± 0.025 to 0.168 ± 0.027, NS). This was accompanied by an increased extraction fraction of glucose, as measured by an increased arteriovenous difference over the forearm (0.16 ± 0.04 to 0.70 ± 0.10 mmol/l; P < 0.001) and by an increase in the estimated arterial-interstitial glucose difference in the gastrocnemius (0.82–1.42 mmol/l) and brachioradialis muscle (0.82–1.97 mmol/l). The blood flow in adipose tissue was significantly increased during insulin infusion, as evidenced by a decreased ethanol outflow-to-inflow ratio (0.369 ± 0.048 to 0.325 ± 0.046; P < 0.01). This was accompanied by an unchanged concentration of glucose in the dialysate (−2.6%, NS). In summary, during physiological hyperinsulinemia 1) a blood flow increase was detected in the calf and forearm, but not in the studied muscles of these limbs; 2) the blood flow increased in the subcutaneous adipose tissue; and 3) the estimated arterial-interstitial glucose difference increased in both muscles studied and was larger in the forearm muscle than the arteriovenous glucose difference over the forearm. The present study shows that microdialysis is a useful tool to obtain tissue-specific information about the effect of insulin on blood flow and glucose extraction in human skeletal muscle and adipose tissue.
Gestational Diabetes: Antepartum Characteristics That Predict Postpartum Glucose Intolerance and Type 2 Diabetes in Latino Women
Authors: Buchanan Thomas A , Xiang Anny , Kjos Siri L , Lee W Paul , Trigo Enrique , Nader Isabel , Bergner E Anne , Palmer Jerry P , Peters Ruth K
Published: September 2013

We examined antepartum clinical characteristics along with measures of glucose tolerance, insulin sensitivity, pancreatic β-cell function, and body composition in Latino women with gestational diabetes mellitus (GDM) for their ability to predict type 2 diabetes or impaired glucose tolerance (IGT) within 6 months after delivery. A total of 122 islet cell antibody-negative women underwent oral and intravenous glucose tolerance tests (OGTT; IVGTT), hyperinsulinemic-euglycemic clamps, and measurement of body fat between 29 and 36 weeks' gestation and returned between 1 and 6 months postpartum for a 75-g OGTT. Logistic regression analysis was used to examine the relationship between antepartum variables and glucose tolerance status postpartum. At postpartum testing, 40% of the cohort had normal glucose tolerance, 50% had IGT, and 10% had diabetes by American Diabetes Association criteria. Independent antepartum predictors of postpartum diabetes were the 30-min incremental insulin:glucose ratio during a 75-g OGTT (P = 0.0002) and the total area under the diagnostic 100-g glucose tolerance curve (P = 0.003). Independent predictors of postpartum IGT were a low firstphase IVGTT insulin response (P = 0.0001), a diagnosis of GDM before 22 weeks' gestation (P = 0.003), and weight gain between prepregnancy and the postpartum examination (P = 0.03). All subjects had low insulin sensitivity during late pregnancy, but neither glucose clamp nor minimal model measures of insulin sensitivity in the 3rd trimester were associated with the risk of IGT or diabetes within 6 months' postpartum. These results highlight the importance of pancreatic β-cell dysfunction, detectable under conditions of marked insulin resistance in late pregnancy, to predict abnormalities of glucose tolerance soon after delivery in pregnancies complicated by GDM. Moreover, the association of postpar-turn IGT with weight gain and an early gestational age at diagnosis of GDM suggests a role for chronic insulin resistance in mediating hyperglycemia outside the 3rd trimester in women with such a β-cell defect.
Contribution of Growth Hormone and IGF-I to Early Diabetic Nephropathy in Type 1 Diabetes
Authors: Cummings Elizabeth A , Sochett Etienne B , Dekker Maria G , Lawson Margaret L , Daneman Denis
Published: September 2013

In children and adolescents with type 1 diabetes, we have reported an association between duration of puberty and the prevalence of nephromegaly and microalbuminuria (MA), which are early markers of diabetic nephropathy. Growth hormone (GH), IGF-I, testosterone, and prorenin are potential mediators of this effect. This study examined the relationship of these hormonal factors to kidney volume (KV) and MA in 155 subjects (78 males, age 13.2 ± 3.5 years [mean ± SD]) with similar diabetes duration (6.83 ± 1.6 years) but varying pubertal experience (0–10 years). KV (by ultrasound), plasma IGF-I, testosterone, prorenin, and NaLi countertransport, and urinary albumin, urinary GH, and urinary IGF-I from three 24-h collections were measured. Multiple regression analysis showed that BSA (P < 0.0001) and urinary IGF-I (P = 0.001) were significantly associated with KV. MA subjects (albumin excretion rate 15–200 μg/min) had higher urinary IGF-I (P = 0.005) and urinary GH (P = 0.05) compared with normoalbuminuric subjects. Only 9% of the variance in urinary IGF-I could be attributed to plasma IGF-I (r = 0.30, P < 0.0001). Testosterone and prorenin were not associated with MA, but they were associated with KV in univariate analyses. The strong association of urinary IGF-I with KV, a marker for glomerular hypertrophy, and of both urinary IGF-I and urinary GH with MA suggests a role for these growth factors in the development of human diabetic nephropathy. Together, these data support animal studies that have shown that renal GH and IGF-I may contribute significantly to the pathogenesis of early diabetic nephropathy.
Enhanced Responsiveness of Blood Pressure to Sodium Intake and to Angiotensin II Is Associated With Insulin Resistance in IDDM Patients With Mcroalbuminuria
Authors: Trevisan Roberto , Bruttomesso Daniela , Vedovato Monica , Brocco Stefano , Pianta Alessandro , Mazzon Cinzia , Girardi Carlo , Jori Elisabetta , Semplicini Andrea , Tiengo Antonio , Prato Stefano Del
Published: September 2013

We assessed blood pressure (BP), body weight, renal hemodynamics, and insulin sensitivity (by euglycemichyperinsulinemic clamp) in nine normoalbuminuric and seven microalbuminuric IDDM patients after 6 days on a low-sodium diet (20 mEq) and after 6 days on a high-sodium diet (250 mEq). In microalbuminuric but not in normoalbuminuric IDDM patients, switching from a low to a high-sodium diet was associated with a significant increase in mean BP (from 92 ± 3 to 101 ± 4 mmHg; P < 0.001) and in body weight (2.91 ± 0.63 vs. 1.47 ± 0.26 kg; P < 0.05). Moreover, under high-sodium conditions, angiotensin II infusion (3 ng · kg−1 · min−1) caused a greater increase in mean BP (14 ± 2 vs. 7.4 ± 1 mmHg; P < 0.05) and a smaller reduction in renal plasma flow (−122 ± 29 vs. −274 ± 41 ml · min−1 · 1.73 m2; P < 0.05) in microalbuminuric than in normoalbuminuric IDDM patients. Under low sodium conditions, aldosterone increments after angiotensin II infusion were lower (P < 0.05) in microalbuminuric than in normoalbuminuric IDDM patients. Insulin-mediated glucose disposal was not affected by sodium dietary content, but it was lower in microalbuminuric (P < 0.05) than in normoalbuminuric IDDM patients. The saltinduced changes in mean BP were related to insulin sensitivity (r = −0.78; P < 0.001). In conclusion, in IDDM patients, microalbuminuria is associated with 1) an increased responsiveness of BP to salt intake and angiotensin II, 2) impaired modulation of renal blood flow, and 3) insulin resistance. Therefore, salt sensitivity in IDDM patients clusters with other factors that are likely to play an important role in the pathogenesis of diabetic nephropathy and its cardiovascular complications.
Kinetics of 65Zinc Uptake and Distribution in Fractions from Cultured Rat Islets of Langerhans
Authors: Figlewicz Dianne P , Formby Bent , Hodgson Alfred T , Schmid Florence G , Grodsky Gerold M
Published: September 2013

Although large quantities of zinc have been measured in pancreatic islets and correlated with islet B-cell function, potential artifacts in histochemical techniques and theexistence of zinc-free insulin in certain species leave its role in insulin storage and secretion unclear. In this investigation, we examined the kinetics of uptake of 65zinc into isolated rat islets and the distribution of both 65zinc and endogenous islet zinc in islet subfractions. In addition, the chemically formed 65zinc-sodium insulin kinetics ofcomplexes were studied.

Net uptake of 65zinc was slow, being almost linear for the first 4 h and not reaching isotopic equilibrium over the 24 h of culture. Culture of islets in high glucose (25.6 mM) resulted in a diminished net 65zinc uptake and significantly decreased content of both endogenous zinc and insulin when compared with culture in low glucose (5.6 mM). Analysis of 65inc and endogenous zinc distribution in islet subfractions revealed a low percentage of 65zinc and endogenous zinc in the granule-enriched fractions: about 90% of total 65zinc and 80% of endogenous zinc were associated with nongranular fractions. A comparison of the specific activity of the granular fractions with the lighter sucrose fractions revealed a nonequilibration of the 65zinc taken up with the granular zinc pool. Chemical analysis of 65zinc-insulin complexes revealed an almost instantaneous binding of 65zinc to zinc-free insulin. Dissociation of preformed 65zincinsulin complexes was slow, but some dissociation occurred with a loweringof the pH.

We demonstrated that net zinc uptake by cultured islets is a slow phenomenon reducedby a high glucose environment. Although chemical analyses suggest a strong affinity of 65zinc for insulin, only small quantities of 65zinc, as well as endogenous zinc, associated with the granule-enriched fractions, and equilibration of granular 65zinc with islet 65zinc pools did not occur over 24 h. Thus, zinc may be needed in other metabolic processes besides insulin crystallization in the Bcell.
Cell-mediated Immunity in Chronically Diabetic Mice
Authors: Roth Michael D , Barg Michele , Michalski Richard , Arquilla Edward R
Published: September 2013

A radioisotopic ear assay for delayed hypersensitivity (DH) to 2,4-dinitrofluorobenzene (DNFB) was used to investigate cellular immune function in chronic alloxan- diabetic C57BI/6 mice. The specific migration of 5-(125I)Iodo-2'-deoxyuridine-labeled monocytes to the site of antigenic challenge was employed to quantitatively measure the OH response. Although both normal and diabetic sensitized mice had a significantly greater DH response than nonsensitized controls, the response of diabetic mice was severely attenuated (23% of normal)

The effect of the delayed hypersensitivity response on spleen size was also investigated. In the nonsensitized state the spleens of diabetic mice were approximately 30% smaller than the spleens of normal mice. After sensitization with DNFB, and up to the time of antigenic challenge, the spleens from both diabetic and normal mice increased 2.1-fold in weight. After challenge, however, the diabetic spleen maintained its prechallenged size while the normal spleen increased an additional 30% in weight.

When either sensitized normal or diabetic spleen cells were passively transferred to nonsensitized normal recipient mice, a significant DH response was evoked after challenge with DNFB. This response was of equal magnitude after transfer of either the sensitized diabetic or normal spleen cells. The DH response after the passive transfer of spleencells from either normal or diabetic sensitized donors to diabetic recipients was very markedly attenuated and in fact questionably significant when compared with the nonspecific inflammatory response to DNFB.

These results indicate that an intact population of DNFB-sensitized cells exists in the diabetic, but that an inhibition of T-lymphocyte or monocyte activity is occurring during the secondary challenge. The chronic hypoinsulinemia, hyperglycemia, and catabolic metabolism of the alloxan-diabetic mouse does not qualitatively alter the immune cellular processes associated with primary sensitization but significantly attenuates the secondary response.
Isolation from Rat Adipocytes of a Chemical Mediator for Insulin Activation of Pyruvate Dehydrogenase
Authors: Kiechle Frederick L , Jarett Leonard , Popp Dennis A , Kotagal Nirmala
Published: September 2013

Insulin treatment of adipocytes increased the amount or activity of a low molecular weight, acid-stable material which, when isolated from intact adipocytes by heat extraction and subsequent Sephadex G25 chromatography, yielded a single active fraction that stimulated mitochondrial pyruvate dehydrogenase by activating the phosphatase and not by altering the kinase activity. Phosphatase activation was demonstrated by the ability of the active material to increase pyruvate dehydrogenase activity in the absence of ATP and by the ability of NaF, a phosphatase inhibitor, to block this stimulation. Involvement of the kinase in this activation mechanism was eliminated by the fact that, in the presence of ATP, (1) NaF completely blocked the stimu ation of pyruvate dehydrogenase by the active fraction, and (2) the stimulation of pyruvate dehydrogenase by dichloroacetic acid, akinase inhibitor, was add itive to the stimulation caused by the active fraction. This active fraction may contain an intracellular chemical mediator or second messenger for insulin.
Human Insulinoma Hybrids Produce Proinsulin-like Material
Authors: Boyd A E , Riser M E , Bolton W E , Siciliano M J
Published: September 2013

We have established somatic cell hybrids by fusing cells from two human insulinomas with an established murine cell line LMTK− CUD. After selection of the hybrids, the media were analyzed and found to contain insulin and human C-peptide immunoreactive material. The newly synthesized material was further characterized by pulse labeling and immunoprecipitation, and shown in five hybrid lines on Sephadex G-50 chroma-tography to have a size similar to proinsulin. The hybrids produced the apparent proinsulin-like material for up to 7 mo. Chromosome composition of the hybrids was determined by isozyme analysis and banding techniques. Chromosome 11, which previously has been assigned the insulin gene using cDNA probes, was identified in the hybrids producing proinsulin-like material. However, the retention of this chromosome did not always assure the production of hormone. This independent technique has confirmed the localization of the insulin gene to chromosome 11 and offers the opportunity of studying insulin processing and developing continuous insulin-producing cell lines.
Retinal Vascular Reactivity to Norepinephrine and Angiotensin II in Normals and Diabetics
Authors: Rhie F H , Christlieb A R , Sandor T , Gleason R E , Rand L I , Shah S T , Soeldner J S
Published: September 2013

Retinal arterial vasoconstriction induced by an infusion of angiotensin II or norepinephrine was investigated in eight normal controls (N), nine diabetics without retinopathy (DNR), and 10 diabetics with retinopathy (DR) by color fundus photographs taken before and after the infusions. Image analysis was done by a semiautomated computerized microdensi-tometer using a videoscanner.

Normal controls and diabetics without retinopathy had a significant reduction in diameter compared with diabetics with retinopathy, who failed to constrict arte-rioles in response to either vasopressor. The mechanism of this phenomenon is unclear.

Semiautomated computerized microdensitometry is reproducible and appears to be a sensitive technique to evaluate the vascular reactivity of the retinal vas-CUlature.
The HLA System in Congenital Rubella Patients With and Without Diabetes
Authors: Rubinstein P , Walker M E , Fedun B , Win M E , Cooper L Z , Ginsberg-Fellner F
Published: September 2013

The HLA antigens of 173 patients with the congenital rubella syndrome (CR) are reported. Twenty-one of these patients are also clinically diabetic, and among them the frequencies of the HLA antigens DR2 and DR3 are significantly lower and higher, respectively, than in CR patients without diabetes or in controls. These data suggest that the genes that control susceptibility to type I or insulin-dependent diabetes mel-litus are necessary for the development of glucose intolerance in CR patients.
Pattern of Histocompatibility (HLA) Antigen Distribution Among Nigerian (West African Black) Diabetics
Authors: Famuyiwa O O , Nwabuebo I E , Abioye A A
Published: September 2013

The pattern of HLA distribution was studied in 70 Nigerian diabetics. There was no association at all between HLA-B8 and insulin-dependent diabetes mellitus (IDDM). There was an increased frequency of HLA-B15 in all categories of patients: those with onset before 40 yr, those with onset after 40 yr (P < 0.05), those with IDDM (P < 0.05), and those with non-insulin-dependent diabetes mellitus (NIDDM). HLA-B7 was slightly increased in frequency contrary to the findings in Caucasian IDDM. HLA-A10 and HLA-Aw32 were increased in all the groups of patients, while HLA-B17 was higher in those with onset after 40 yr (P < 0.02) and NIDDM (P < 0.02). HLA-Bw35 was decreased in all categories of patients. However, all the observed deviations fell short of statistical significance when correction was made for the number of antigens tested for.

Comparison of the data with those in other black populations revealed that the over-all pattern of HLA distribution in black diabetics is rather disparate and still relatively ill-defined. It is concluded that the pattern of HLA and diabetes association in Nigerian diabetics would appear to be different from that in most other racial groups including North American and South African blacks. There is, however, a need to further study larger numbers of Nigerian diabetics and other black population groups so that a clearer picture may emerge.
Immediate Elimination of Labile HbA1c With Allosteric Effectors of Hemoglobin
Authors: Nakashima Koji , Hattori Yukio , Yamazaki Kazutoshi , Takechi Masahiro , Andoh Yukio , Miyaji Takaoki
Published: September 2013

Our aim was to find a simple method of removing labile glycosylated hemoglobin (HbA1c) from blood samples before it is measured by cation-exchange chromatography. Labile HbA1c is formed by the binding of glucose to the NH2-terminal valine of the β-chain of HbA. We sought a more competitive binder for the same site to dissociate labile HbA1c to glucose and HbA. Inorganic phosphates were found to have a strong allosteric effect and a great ability to eliminate labile HbA1c. We developed our method with 4 mM tetrapolyphosphate in the hemolyzing solution to eliminate labile HbA1c during the automatic processing (at pH 6 and heated for 2 min at 45°C) of blood samples for HbAlc estimation. This may be useful when estimating HbA1c by the manual method.
Family of Glucose-Transporter Genes: Implications for Glucose Homeostasis and Diabetes
Authors: Mueckler Mike
Published: September 2013

Glucose transport by facilitated diffusion is mediated by a family of tissue-specific membrane glycoproteins. At least four members of this gene family have been identified by cDNA cloning. The HepG2-type transporter is the most widely distributed of these proteins. It provides many cells with their basal glucose requirement for ATP production and the biosynthesis of sugar-containing macromolecules. The liver-type transporter is expressed in tissues from which a net release of glucose can occur and in β-cells of pancreatic islets. A genetic defect resulting in reduced activity of this transporter could hypothetically lead to the two principal features of non-insulin-dependent diabetes mellitus, insulin resistance and relative hypoinsulinemia. The adipocyte/muscle transporter is expressed exclusively in tissues that are insulin sensitive with respect to glucose uptake. This protein is an excellent candidate for a highly specific genetic defect predisposing to insulin resistance.
Interaction Between Insulin and Glucose-Delivery Route in Regulation of Net Hepatic Glucose Uptake in Conscious Dogs
Authors: Adkins-Marshall Bess A , Myers Sharon R , Hendrick Grant K , Williams Phil E , Triebwasser Keith , Floyd Ben , Cherrington Alan D
Published: September 2013

In the presence of fixed basal levels of insulin, the route of intravenous glucose delivery (portal vs. peripheral) determines whether net hepatic glucose uptake (NHGU) occurs. Our aims were to determine if the route of intravenous glucose delivery also plays a role in regulating NHGU in the presence of hyperinsulinemia and to determine if length of fast (18 vs. 36 h) influences regulation of NHGU. Five conscious dogs fasted 18 h were given somatostatin and replacement insulin (245 ± 34 μU · kg−1 · min−1) and glucagon (0.65 ng · kg−1 · min−1) infusions intraportally. After a 40-min control period, the insulin infusion rate was increased fourfold, and glucose was infused for 3 h. Glucose was given either through a peripheral vein or the portal vein for 90 min to double the glucose load reaching the liver. The order of infusions was randomized. NHGU was measured with the arterial – venous difference technique. Insulin and glucagon levels were 12 ± 2, 35 ± 6, and 36 ± 5 μU/ml and 55 ± 12, 61 ± 13, and 59 ± 7 pg/ml during the control, peripheral, and portal infusions, respectively. The glucose infusion rate, the load of glucose reaching the liver, and the arterial-portal plasma glucose gradient were 0, 9.58 ± 2.28, and 10.44 ± 2.94 mg · kg−1 · min−1; 29.4 ± 3.6, 56.8 ± 3.4, and 56.8 ± 2.8 mg · kg−1 · min−1; and 2 ± 1, 5 ± 1, and −51 ± 15 mg/dl during the same periods. The liver switched from net glucose output (2.5 ± 0.4 mg · kg−1 · min−1) to uptake of 1.4 ± 0.7 and 3.5 ± 0.8 mg · kg−1 · min−1 during peripheral and portal glucose delivery, respectively. Despite a similar hormonal milieu and indistinguishable glucose loads, there was significantly (P < 0.01) more NHGU when glucose was infused intraportally. Identical studies in five conscious dogs fasted 36 h gave results similar to those of dogs fasted 18 h. After 36 h of fasting, NHGU was 1.6 ± 0.4 and 4.0 ± 0.4 mg · kg−1 · min−1 during the peripheral and portal glucose infusions, respectively (P < 0.005). In conclusion, the route of intravenous glucose administration plays an important role in regulating NHGU even in the presence of hyperinsulinemia in conscious dogs fasted 18 and 36 h.
HLA-DQβ Sequence Polymorphism and Genetic Susceptibility to IDDM
Authors: Erlich Henry A , Bugawan Teodorica L , Scharf Stephen , Nepom Gerald T , Tait Brian , Griffith Robert L
Published: September 2013

The analysis of HLA-DQβ nucleotide sequence polymorphism in insulin-dependent diabetes mellitus (IDDM) patients and control subjects suggests a role for the DQβ-chain in genetic susceptibility. Sequence determination and oligonucleotide hybridization was carried out on enzymatically amplified DNA from various HLA-DR-typed individuals, including the rare class of DR2+ patients. In the analysis of DQβ variation in DR4, DRw6, and DR2 haplotypes, a correlation was observed between the presence of the negatively charged residue Asp at position 57 and low susceptibility and the presence of an Ala (DR4), Val (DRw6), or Ser (DR2) and higher susceptibility. However, important exceptions to this pattern have been identified in the analysis of heterozygous DR1/4 IDDM patients. In these individuals, susceptibility appears to correlate with specific DRβ1 alleles (Dw4) on the DR4 haplotype, rather than with the DQβ allele (DQB3.2) that contains Ala at position 57. The DQβ alleles found in some Chinese IDDM patients also proved discordant with the position-57 correlations. Thus, although there is a general correlation between the residue at position 57 of the DQβ-chain and IDDM susceptibility, these data do not support the notion that Asp 57 confers complete resistance or protection to IDDM. In general, these results suggest that IDDM susceptibility is conferred by specific combinations of DQβ and DRp sequences.
Loss of Self-Tolerance to ICA69 in Nonobese Diabetic Mice
Authors: Karges Wolfram , Hammond-McKibben Denise , Gaedigk Roger , Shibuya Noriko , Cheung Roy , Dosch Hans-Michael
Published: September 2013

Islet cell antigen p69 (ICA69) is a target autoantigen in IDDM. Studies of T-cells from newly diabetic children suggested possible antigenic mimicry between human ICA69 (in particular the Tep69 T-cell epitope, aa 36-47) and the ABBOS region in bovine serum albumin (BSA; aa 152-169), one of several cow's milk proteins that evoke abnormal immunity in diabetes-prone hosts. We recently found the sequence of Tep69 regions to be identical in the four alternatively spliced human and rodent ICA69 isoforms. Immunization of nonobese diabetic (NOD) mice with BSA or ICA69 generates fully cross-reactive T-cell responses to both Tep69 and ABBOS as the immunodominant, naturally generated, and presented T-cell mimicry epitopes. Such responses are absent or weak in healthy strains of mice. NOD mouse recipients of adoptive spleen cell grafts from diabetic donors spontaneously generate easily detectable pools of T-cells specific for ICA69/BSA, as well as the unrelated GAD65. NOD mice injected neonatally with ABBOS or Tep69 show cross-tolerance, but ABBOS-induced tolerance is transient. Neonatal injection of Tep69 reduces disease incidence (23 vs. 68% IDDM, P < 0.02), while neonatal injection of ABBOS has little effect. In contrast, systemic immunization of young NOD females with ABBOS (but not Tep69) reduces the diabetes incidence and delays disease expression, with protected mice generating ABBOS-specific T-cell repertoires unable to recognize the Tep69 mimicry antigen. Our observations demonstrate a loss of self-tolerance to ICA69 in NOD mice, and they establish antigenic mimicry between the two T-cell epitopes in ICA69 and BSA. Further studies are necessary to understand the molecular basis of this mimicry and how either T-cell peptide can modify the disease course.
Targeted Overexpression of Cu/Zn Superoxide Dismutase Protects Pancreatic β-Cells Against Oxidative Stress
Authors: Michael Kubisch H , Wang Junqiang , Bray Tammy M , Phillips John P
Published: September 2013

Current evidence suggests that reactive oxygen species (ROS) may participate in the destruction of pancreatic β-cells leading to type 1 diabetes. Genetic factors predisposing individual susceptibility to type 1 diabetes might therefore include those affecting the efficacy of ROS metabolism. In a direct in vivo test of this hypothesis, we have generated strains of mice carrying trans-genes that supplement basal levels of the radical-scavenging enzyme Cu/Zn Superoxide dismutase in the pancreas via directed expression in β-cells. Expression of these transgenes significantly enhances resistance to alloxan-induced diabetogenesis above that of control animals, thereby providing direct in vivo evidence that genetic variation in ROS metabolism can affect susceptibility to oxidative stress-mediated diabetogenesis.
Immunohistochemical Study of Prostacyclin-Stimulating Factor (PSF) in the Diabetic and Atherosclerotic Human Coronary Artery
Authors: Sekiguchi Naotaka , Umeda Fumio , Masakado Mitsmiori , Ono Yasuhiro , Hashimoto Toshihiko , Nawata Hajime
Published: September 2013

Prostacyclin (PGI2) synthesis by vascular endothelial cells (ECs) decreases in diabetic subjects, possibly leading to the development of diabetic angiopathy, such as that seen in atherosclerosis. We recently found a novel bioactive peptide, prostacyclin-stimulating factor (PSF), which stimulates PGI2 synthesis by cultured aortic ECs. Our previous studies demonstrated that PSF is dominantly expressed by arterial smooth muscle cells (SMCs). In the present study, we found PSF to exist in the SMCs of human coronary arteries by means of immunohistochemical methods. Human coronary arteries obtained from autopsies were divided into four subgroups, with or without NIDDM and/or myocardial infarction. Immunostaining for PSF was performed by the avidin-biotin peroxidase complex method using a purified anti-PSF antibody, and the immunostaining for PSF was assessed semiquantita-tively. PSF staining was markedly reduced in coronary arterial SMCs from patients with NIDDM and/or myocardial infarction. In addition, the effect of a high glucose culture on PSF mRNA expression and PSF production in bovine aortic SMCs was examined by immunocytochemical staining and both Western and Northern blot analyses. The immunostaining and immunoblot band for PSF also significantly decreased when bovine aortic SMCs were cultured with high concentrations of glucose. Furthermore, as compared with the SMCs cultured with a physiological glucose concentration, the density ratio of PSF mRNA to 28S rRNA expression significantly decreased when the SMCs were cultured with high concentrations of glucose. These results strongly suggest that the decreased PSF production may thus result in a decreased production of PGI2 in the coronary artery, thus leading to the development of both diabetic macroangiopathy and atherosclerosis.
Maturity-Onset Diabetes of the Young Due to a Mutation in the Hepatocyte Nuclear Factor-4α Binding Site in the Promoter of the Hepatocyte Nuclear Factor-1α Gene
Authors: Gragnoli Claudia , Lindner Tom , Cockburn Brian N , Kaisaki Pamela J , Gragnoli Fabio , Marozzi Gino , Bell Graeme I
Published: September 2013

Recent studies have shown that mutations in the transcription factor hepatocyte nuclear factor (HNF)-1α are the cause of one form of maturity-onset diabetes of the young (MODY3). These studies have identified mutations in the mRNA and protein coding regions of this gene that result in the synthesis of an abnormal mRNA or protein. Here, we report an Italian family in which an A→C substitution at nucleotide -58 of the promoter region of the HNF-1α gene cosegregates with MODY. This mutation is located in a highly conserved region of the promoter and disrupts the binding site for the transcription factor HNF-4α, mutations in the gene encoding HNF-4α being another cause of MODY (MODY1). This result demonstrates that decreased levels of HNF-1α per se can cause MODY. Moreover, it indicates that both the promoter and coding regions of the HNF-1α gene should be screened for mutations in subjects thought to have MODY because of mutations in this gene.
Genetic Variation of the Heparan Sulfate Proteoglycan Gene (Perlecan Gene): Association With Urinary Albumin Excretion in IDDM Patients
Authors: Hansen P M , Chowdhury T , Deckert T , Hellgren A , Bain S C , Pociot F
Published: September 2013

Both in patients with IDDM (1) and in healthy control subjects (2,3), increased urinary albumin excretion rate (AER) is associated with high relative morbidity and mortality. In IDDM patients, genetic susceptibility factors are most likely contributing to an increased AER (4,5) resulting in a cumulative incidence of nephropathy (AER >300 mg/24 h) of -30% (6). So far, candidate genes, proposed as susceptibility markers linked to abnormal albuminuria, have been identified because of the knowledge of pathophysiological events related to diabetic nephropathy. Heparan sulfate proteoglycan (HSPG, i.e., Perlecan) constitutes an integrated part of the glomerular basement membrane. It consists of a central core protein to which anionie sulfated polysaccharide chains (heparan sulfate [HS]) are linked (7), thus contributing to the negative charge of the glomerular filtration barrier and thereby indirectly to the composition of the glomerular filtration product (8,9). In IDDM patients, it has been demonstrated that increased AER is reduced by the administration of heparin (10) most likely because of a stimulating effect on the HS synthesis (11).
Incidence of sterile hemorrhagic cystitis in dogs receiving cyclophosphamide orally for three days without concurrent furosemide as part of a chemotherapeutic treatment for lymphoma: 57 cases (2007–2012)
Authors: Best Matthew P. , Fry Darren R.
Published: September 2013

Objective—To evaluate the incidence of sterile hemorrhagic cystitis (SHC) and other adverse effects in dogs following oral administration of the single-day, maximum-tolerated dose (MTD) of cyclophosphamide divided over 3 days as part of a multiagent chemotherapy protocol for treatment of lymphoma without concurrent administration of furosemide.

Design—Retrospective case series.

Animals—57 dogs.

Procedures—Medical records were reviewed to identify dogs with lymphoma that underwent the described cyclophosphamide treatment. Information was obtained regarding signalment, lymphoma stage, concurrent diseases, cyclophosphamide doses administered, adverse effects (including SHC), remission rates, and outcomes. The incidence of SHC was compared with that of literature-derived historical control groups that received the MTD of cyclophosphamide as a single, 1-day dose with or without furosemide treatment.

Results—None of the 57 dogs developed SHC during the study period. Forty-seven of 57 (82%) dogs had complete remission of lymphoma. Other adverse effects were uncommon and self-limiting; no dogs had myelosuppression, and only 5 had mild gastrointestinal effects. Incidence of SHC was significantly lower than that reported for historical control dogs that received cyclophosphamide as a single dose without furosemide (24/219) and was not significantly different from that for historical control dogs that received cyclophosphamide as a single dose with furosemide (2/139).

Conclusions and Clinical Relevance—No dogs in this study had SHC following oral administration of the single-day MTD of cyclophosphamide divided over a 3-day period without furosemide administration. Further research is needed to confirm whether this method of cyclophosphamide administration is equivalent or superior to the current single-dose administration method.
Inhibition of Digestive α-Amylases from Chilo Suppressalis Walker (Lepidoptera: Crambidae) by a Proteinaceous Extract of Citrullus Colocynthis L. (Cucurbitaceae)
Authors: Valizadeh Bita , Zibaee Arash , Sendi Jalal Jalali
Published: September 2013

The striped rice-stem borer, Chilo suppressalis (Walker) is one of the most important pest of rice worldwide. In this study, a proteinaceous extract from Citrullus colocynthis L. shows various degrees of inhibition to digestive α-amylases of C. suppressalis. Digestive α-amylases of larvae were inhibited by different concentrations (approximately 50%) of C. colocynthis amylase inhibitor (CCAI). One of the isozymes totally disappeared and the sharpness of another decreased on native-PAGE electrophoresis. The pH dependency of inhibition revealed that the enzyme was inhibited in a wide range of pH from 7-10, and the optimal pH of the enzyme occurred in lepidopteran larvae. The highest inhibition of α-amylase by CCAI was observed at 25°C; the temperature near the optimal temperature of amylolytic activity. A time-course experiment demonstrated that enzymatic activity was the highest, 30 min after the onset of the experiment, when the highest inhibition occurred. The enzyme kinetic studies using Lineweaver-Burk analysis, revealed a mixed inhibition of CCAI on α-amylase activity. The current study is the first basic one using α-amylase inhibitor against C. suppressalis. This study opens the way for transgenic rice varieties containing inhibitors
Evaluation of some Accessions of Bambara Groundnut (Vigna Subterranean L. Verdc) for Resistance to Bruchid Infestation, Based on Grain Source and Seed Coat Colour
Authors: Echezona Bonaventure Chukwujindu , Amuji Chinedu Felix , Eze Simon
Published: September 2013

The relative susceptibility of different accessions of Bambara groundnut (Vigna subterranean L. Verdc) to Callosobruchus maculatus (F.) was assessed in a laboratory trial in Nigeria. Treatments were comprised factorial combinations of four grain sources from Nigeria (Enugu, Anambra, Benue and Kogi state) and three predominantly contrasting seed coat colours (black, brown, and milky-colour) laid out in a completely randomized design (CRD). There were four replications of each treatment. Egg depositions by adult C. maculatus were affected by grain sources such that ovipositions on those sourced from the state of Anambra were significantly (p < 0.05) higher than those from other sources. Similarly, black coloured grains harboured more insects and eggs compared to other seed coat colours. Accesssions collected from Benue and/or those with a milky-coloured seed coat showed some levels of oviposition deterrence. However, the interaction of grain source and seed coat colour was not significant based on oviposition, adult emergence, and mortality counts. Grain sources and seed coat colour were, therefore, important traits to be considered while selecting ideotypes for resistance to C. maculatus
Effect of Neem Pesticide (Achook) on Midgut Enzymatic Activities and Selected Biochemical Compounds in the Hemolymph of Lesser Mulberry Pyralid, Glyphodes Pyloalis Walker (Lepidoptera: Pyralidae)
Authors: Khosravi Roya , Sendi Jalal Jalali
Published: September 2013

Synthetic organic compounds and those of plant origin used in insect pest control are known to affect digestive enzymes and biochemical compounds. The lesser mulberry pyralid Glyphodes pyloalis Walker is a monophagous and dangerous pest of mulberry that has been recently observed in Guilan province, northern Iran. In this study the effect of the neem formulation, Achook (0.03% azadirachtin) was studied on nutritional physiology and gut enzyme activity of the lesser mulberry pyralid G. pyloalis. The LC25, LC50, and LC90 values on 4th instar larvae were estimated as 113.6, 256.84, and 1,210.02 ppm, respectively. The neem insecticide exhibited a significant antifeedant activity when used at the highest concentration. When G. pyloalis larvae were provided with mulberry leaves treated with the neem extract, all nutritional indices, except approximate digestibility, decreased. Neem was found to affect digestive enzyme activities in the midgut of treated larvae. When larvae were fed on treated leaves, biochemical compounds in the hemolymph, such as protein, lipid, and glucose decreased but the amount of uric acid increased compared with the control