bluuebunny/crossref_metadata_2025 huggingface dataset:
Heart Transplantation in Mildly Diabetic Patients
Authors: Faglia Ezio , Favales Fabrizio , Mazzola Ester , Pizzi Gianluigi , De Renata , Mangiavacchi Maurizio , Gronda Edoard , Caroli Angelo , Zaina Meri S
Published: September 2013

From 1985 to 1989, 67 heart transplantations were performed in our hospital, 6 of them in non-insulin-dependent (type II) diabetic patients. Six pretransplantation type II diabetic male heart recipients (mean ± SD age 50.0 ± 7.3 yr) were compared with 61 nondiabetic recipients (mean age 44.5 ±11.0 yr; 55 men, 6 women) to define whether a different posttransplantation prognosis may be caused by pretransplantation diabetes. Before transplantation, all diabetic recipients (3 newly diagnosed and 3 with diabetes duration of 5, 6, and 12 yr, respectively) were in good glycemie control (mean fasting blood glucose 7.95 ± 1.62 mM, mean HbA1c 7.6 ± 0.2%). None had ocular or renal microangiopathic complications, 5 were treated only with diet, and 1 was treated with oral hypoglycemic agents. All recipients were treated with the same immunosuppressive protocol (cyclosporin, prednisone, and since 1986, azathioprine and antilymphocyte globulin), and mean dose and blood levels of cyclosporin were not significantly different between diabetic and nondiabetic recipients. After heart transplantation (mean follow-up 558 ± 340 days in diabetic and 379 ± 338 in nondiabetic recipients), the mortality rate and complications (i.e., rejection episodes, supplementary immunosuppressive treatments, major and minor infections, arterial hypertension, and graft atherosclerosis) showed no significant differences except for the more frequent arterial hypertension in diabetic recipients (P < 0.05), although pretransplantation incidence of hypertension was lower in diabetic candidates. Even during immunosuppressive treatment, including corticosteroids, diabetic recipients had good metabolic control (mean fasting blood glucose 6.32 ± 1.96 mM, mean HbA1c 5.3 ± 0.5% at the 6th mo). Three recipients were treated with insulin and/or oral hypoglycemic agents, and 1 recipient was treated with diet only. Serum cholesterol, triglycerides, and creatinine levels did not vary significantly between the two groups in posttransplantation follow-up. After heart transplantation, pretransplantation diabetic recipients in good metabolic control and without microangiopathic complications had the same prognosis in this series as nondiabetic recipients at this stage of follow-up.
Gut Exchange of Glucose and Lactate in Basal State and After Oral Glucose Ingestion in Postoperative Patients
Authors: Björkman Ola , Eriksson L Siw , Nyberg Björn , Wahren John
Published: September 2013

Glucose uptake by the intestine and its conversion into 3-carbon compounds in the human intestine in the basal state and after an oral glucose load are not understood. Consequently, we studied the arterial and portal venous concentration differences (A-PV) for glucose and glucogenic substrates in the basal state and 3 h after the ingestion of a 100-g glucose load with the catheter technique. Five patients were studied 3–11 days after surgery for gallbladder disease or cancer of the colon or liver. A-PV for glucose in the basal state was 0.12 ± 0.02 mM (P < 0.01), indicating net glucose uptake by extrahepatic splanchnic tissues. No net exchange of lactate or pyruvate was detected, but there was release of alanine and uptake of glutamine. After glucose ingestion, glucose was released by the gut, reflecting absorption of the load (mean A-PV for glucose −2.10 ± 0.04 mM, P < 0.01). The arterial glucose concentration rose gradually from 4.6 ± 0.1 mM before glucose ingestion to a plateau at 9.5 ± 0.7 mM from 90 to 180 min. Glucose ingestion was accompanied by net lactate and alanine release (A-PV −0.16 ± 0.06 mM and −48 ± 7 μM, respectively), whereas A-PV for pyruvate did not change. We conclude that, in postoperative patients, there is a significant net glucose uptake by the gastrointestinal tract in the basal state. Glucose ingestion is accompanied by a small release of lactate and alanine from the intestine. However, the estimated net gut formation of lactate and alanine can play only a minor role in the disposal of an oral glucose load.
HLA-DP Variation as Additional Risk Factor in IDDM
Authors: Easteal Simon , Kohonen-Corish Maija R J , Zimmet Paul , Serjeantson Susan W
Published: September 2013

A significant increase in the frequency of DPw3/6 aleeles defined by restriction-fragment–length polymorphism is observed in insulin-dependent diabetes mellitus (IDDM) patients relative to healthy control subjects (34.6 vs. 10.5%, P < 0.009). Log-linear modeling demonstrates that this association is independent of HLA-DR3 and -DR4 and IDDM association and cannot be attributed to linkage disequilibrium between HLA-DP and -DR. The analysis also demonstrates an absence of interactive effects among the antigens in conferring IDDM susceptibility. The strength of the DPw3/6 association is not significantly less than that of either DR3 or DR4.
Transgenic Mouse Models of Type I Diabetes
Authors: Lipes Myra A , Eisenbarth George S
Published: September 2013

Transgenic mouse technology has gained recognition as an important tool for examining many fundamental biological questions in vivo. Recently, transgenic mouse techniques have been applied to the study of type I (insulin-dependent) diabetes. These studies have been particularly informative in elucidating 1) mechanisms whereby immune tolerance is maintained to antigens on rare specialized cells such as the pancreatic β-cell, 2) disease susceptibility and resistance genes, and 3) potentially important immune effector mechanisms. In this article, we discuss these studies, their impact on understanding of the pathogenesis of type I diabetes, and the potential of the transgenic mouse approach for future research.
Adaptation of Cholinergic Enteric Neuromuscular Transmission in Diabetic Rat Small Intestine
Authors: Nowak Thomas V , Harrington Bonnie , Kalbfleisch John
Published: September 2013

Representative longitudinal muscle strips (6 × 10 mm) from distal small intestine were obtained from rats after 1, 2, and 3 mo of streptozocin-induced diabetes. The strips were stretched to their optimum lengths and subjected to electrical field stimulation (1-ms pulse duration, 30–270 mA, 10 Hz) in the presence of Krebs solution and Krebs solution plus 10−6 M atropine. Field stimulation produced atropine-sensitive and atropine-resistant contractions in all strips. After 1 mo, significant differences in the amplitudes of the atropine-sensitive contractions were found between the diabetic rats and nondiabetic controls. Insulintreated diabetic rats showed contraction responses that were intermediate in amplitude. After 2 mo, the difference between the control and diabetic groups was less evident but still significant. After 3 mo, the previously noted difference in the atropine-sensitive contractions between the diabetic and control groups had resolved. No significant differences among the three groups were noted in the amplitudes of the atropine-resistant contractions. Field stimulation delivered at pulse durations of 50 ms in the presence of neural blockade with tetrodotoxin (5 × 10−6 M) produced similar contraction amplitudes among the three groups at any respective time phase of the study. Dose-response studies of intestinal muscle after 3 mo of untreated diabetes showed normal tension development to both bethanechol chloride and physostigmine. These results indicate that streptozocin-induced diabetes is acutely associated with defective cholinergic neuromuscular transmission in the myenteric plexus of the distal small intestine The abnormality is less evident after 2 mo of untreated diabetes and resolves spontaneously after 3 mo. Insulin treatment appears to accelerate this resolution.
Association of Painful and Painless Diabetic Polyneuropathy With Different Patterns of Nerve Fiber Degeneration and Regeneration
Authors: Britland Stephen T , Young Robert J , Sharma Ashutosh K , Clarke Basil F
Published: September 2013

We evaluated neuropathological abnormalities in sural nerve biopsies from 6 nondiabetic control subjects and 16 age-matched diabetic patients with different syndromes of sensory polyneuropathy (6 with chronic painful neuropathy [CPN], 4 with newly presenting painful neuropathy [NPN], and 6 with painless neuropathy associated with recurrent neurotrophic foot ulcers [RFU]). Although all but one of the evaluated features of myelinated and unmyelinated fiber pathology could be found in every diabetic patient, certain myelinated fiber abnormalities were associated with the clinical characteristics of the neuropathy. Thus, myelinated fiber density was severely reduced, “empty” Schwann tubes (an index of myelinated fiber degeneration) were increased, and early regeneration (bands of Bungner [BB], nonmyelinated axons) was pronounced in the RFU group. Progression from BB to regenerating myelinated fiber cluster (myelination and maturation) was more successful in patients with CPN and NPN than in those with RFU, and the finding of fibers with disproportionately large Schwann cells (cytoplasm and myelin) relative to axon caliber was exclusive to patients with neuropathic pain. We concluded that 1) unequal rates of successful fiber regeneration may cunderlie the apparent difference in the extent of myelinated fiber loss between painful and painless diabetic polyneuropathy; 2) myelinated and unmyelinated fiber degeneration and regeneration per se are probably not the cause of neuropathic pain in diabetic polyneuropathy, because each occurred in patients with RFU; and 3) axonal atrophy may be involved in neuropathic pain generation.
Early Onset of Increased Transcapillary Albumin Escape in Awake Diabetic Rats
Authors: Tucker Bryan J
Published: September 2013

Alteration in transcapillary albumin escape rate (TERa,alb) is an indicator of changes in macromolecular movement at the capillary filtering bed, which can change the balance of Starling forces for fluid movement from the vasculature to the interstitium and has an impact on volume homeostasis. TERalb can be affected by morphological changes in the capillary membrane and/or alterations in the Starling forces driving larger solutes across the capillary membrane via convection. Previous studies have demonstrated an increased TERalb in established insulin-dependent diabetes (IDDM); however, whether increased TERalb is the result of morphological alterations in the microvasculature or contributes to microangiopathies could not be resolved. TERalb was examined in awake Wistar rats with untreated IDDM induced by streptozocin infusion (65 mg/kg body wt i.v.) at 24 h and 7 and 15 days and compared with control and insulin-treated 7-day IDDM rats. Increased TERalb occurred at the 24-h time point and remained elevated at 7 and 15 days of IDDM (P < 0.05). Blood volume remained unchanged; however, systemic protein concentration increased from 4.9 ± 0.1 g/dl in controls to 6.4 ± 0.4 g/dl in 15-day IDDM rats. Blood glucose was significantly increased, and glycosuria was evident at all three time points of IDDM. The observed increase in TERalb within 24 h of IDDM is indicative of a functional change in the Starling forces in the capillaries, because specific morphological capillary damage is not evident at this time point in the model. The early onset of TERalb in IDDM could indicate functional changes, such as capillary hypertension, and may contribute to future vascular complications in established IDDM.
Reversal of Glomerular Hyperfiltration and Renal Hypertrophy by Blood Glucose Normalization in Diabetic Rats
Authors: Stackhouse Stephanie , Miller Peter L , Park Sung Kwang , Meyer Timothy W
Published: September 2013

Two groups of rats with streptozocin-induced diabetes and one group of nondiabetic control rats were studied. Group 1 diabetic rats received daily insulin to maintain blood glucose levels at 300–400 mg/dl for 44 wk. Group 2 diabetic rats received the same insulin regimen for 37 wk and then received an increased dose of insulin to return blood glucose levels close to normal for 7 wk. Group 3 nondiabetic rats were age-matched controls. Glomerular filtration rate (GFR) and kidney weight were elevated in moderately hyperglycemic group 1 rats compared with group 3 rats. Normalization of blood glucose returned both GFR (group 1,1.83 ± 0.04 ml/min; group 2,1.36 ± 0.05 ml/min; group 3,1.45 ± 0.07 ml/min) and kidney weight (group 1, 2.55 ± 0.06 g; group 2,1.82 ± 0.05 g; group 3,1.72 ± 0.06 g) to normal in group 2 rats. Despite a sustained increase in GFR, group 1 rats did not exhibit any increase in glomerular volume (group 1, 2.77 ± 0.09 × 106 μm3; group 2, 2.69 ± 0.09 × 106 μm3; group 3, 2.81 ± 0.7 × 106 μm3). Group 1 rats did, however, exhibit a significant increase in glomerular mesangial volume (group 1, 0.31 ± 0.02 × 106 μm3; group 2, 0.28 ± 0.02 × 106 μm3; group 3, 0.21 ± 0.01 × 106 μm3), which was not reversed by normalization of blood glucose in group 2. These findings show that normalization of blood glucose can reverse established glomerular hyperfiltration and renal hypertrophy in moderately hyperglycemic diabetic rats. They further indicate that mesangial expansion is associated with sustained moderate hyperglycemia in this disease model.
Inhibition of Insulin and Somatostatin Secretion and Stimulation of Glucagon Release by Homologous Galanin in Perfused Rat Pancreas
Authors: Miralles Paloma , Peiró Elena , Dégano Pilar , Silvestre Ramona A , Marco José
Published: September 2013

Results of studies on the effects of exogenous galanin on islet cell secretion are controversial. Until recently, only pig galanin has been available, and structural dissimilarities among the galanin molecules of different species might have contributed to discrepancies among the study results. Thus, we investigated the influence of synthetic rat galanin (50 nM) on unstimulated insulin, glucagon, and somatostatin release and on the responses of these hormones to arginine (10 mM), glucose (16.6 mM), and vasoactive intestinal polypeptide (VIP; 1 nM) in a homologous animal model, the perfused rat pancreas. In addition, the effect of an equimolar concentration of pig galanin on arginine-induced islet cell secretion was examined. Infusion of rat galanin reduced unstimulated insulin release (∼60%, P < 0.01) and the insulin responses to arginine (∼30%, P < 0.025), glucose (100%, P < 0.01), and VIP (∼80%, P < 0.025). Galanin also inhibited unstimulated somatostatin secretion (∼15%, P < 0.05) and virtually abolished the somatostatin output evoked by arginine, glucose, and VIP. Conversely, rat galanin increased unstimulated glucagon output (∼20%, P < 0.05), potentiated the glucagon response to arginine (∼50%, P < 0.05) and VIP (∼90%, P < 0.05), and counteracted the suppressor effect of glucose on α-cell secretion. Pig galanin inhibited the insulin output elicited by arginine (∼45%, P < 0.05) but did not affect the somatostatin and glucagon responses to the aminogenic stimulus. In conclusion, the opposite effects of galanin on insulin and glucagon secretion favor the concept of galanin as a diabetogenic agent. Galanin also behaves as a potent inhibitor of somatostatin release. Finally, the importance of using homologous galanin to study the biological activity of this peptide must be emphasized.
Impaired Mitogen-Induced Expression of High-Affinity Interleukin 2 Receptors on Spleen Cells From NOD/Shi/Kbe Mice
Authors: Hatamori Nobuo , Yokono Koichi , Nagata Masao , Shii Kozui , Baba Shigeaki
Published: September 2013

The immune abnormalities of NOD mice, a model of human type I (insulin-dependent) diabetes, have been postulated to be T-lymphocyte dependent. We measured responsiveness to exogenous interleukin 2 (IL-2) and IL-2 production in spleen mononuclear cells from female NOD/Shi/Kbe mice after stimulating the cells with concanavalin A (ConA blasts) or phytohemagglutinin (PHA blasts). Exogenous IL-2 produced significantly lower proliferative responses in each blast from 3- and 10-wk-old NOD/Shi/Kbe mice than from control strains. IL-2 production in NOD/Shi/Kbe mice was inclined to decrease but not significantly compared with controls. Even sufficient amounts of recombinant IL-2 (rlL-2) or IL-1 (rlL-1), added with mitogens to the preculture medium, failed to provoke normal proliferative responses from NOD/Shi/Kbe mouse cells. To clarify the reason for this defect, we investigated the expression of IL-2 receptors (IL-2Rs) on mitogen-activated cells with anti- IL-2R monoclonal antibody (PC61) and radiolabeled IL-2. Cytofluorometry showed no significant difference between strains in the number of PC61+ ConA and PHA blasts. However, Scatchard analysis with 125I-labeled IL-2 showed that the number of high-affinity IL-2Rs (H-IL-2Rs), the mediators of the biological activity of IL-2, was decreased in NOD/Shi/Kbe mice compared with controls, whereas the number of lowaffinity IL-2Rs (L-IL-2Rs) was not different. Separating the L3T4+ and Lyt-2+ populations of T lymphocytes by cell sorting showed both to be deficient in H-IL-2Rs. Chemical cross-linking of 125I-IL-2 bound to H-IL-2Rs on ConA blasts generated the labeling of both IL-2R p70 and p55 proteins (proteins of 70,000 and 55,000 Mr, respectively). These proteins were quantifiably less radioactive in the NOD/Shi/Kbe mice. These studies suggest that the impaired H-IL-2R expression on mitogen-activated splenic T lymphocytes may be involved in the pathogenesis of type I diabetes in NOD/Shi/Kbe mice.
Inhibition of Cytokine-Induced MHC Class II but Not Class I Molecule Expression on Mouse Islet Cells by Niacinamide and 3-Aminobenzamide
Authors: Yamada Kentaro , Miyajima Emi , Nonaka Kyohei
Published: September 2013

Normal mouse islet cells express low levels of MHC class I molecules and undetectable or extremely low levels of MHC class II molecules. Class I expression was dose-dependently augmented by incubation with interferon-γ (IFN-γ) or tumor necrosis factor (TNF). Although neither IFN-γ nor TNF alone induce class II molecules on islet cells, synergistic interaction of IFN-γ (200 U/ml) and TNF (200 U/ml) may induce class II expression on ∼50% of islet cells. Niacinamide and 3-aminobenzamide, both inhibitors of ADP ribosylation and scavengers of free radicals, attenuated the class II expression induced by IFN-μ and TNF. Twenty millimolar niacinamide and 10 mM 3-aminobenzamide reduced the rates of class II antigenpositive cells to mean ± SD 3.6 ± 0.3 and 6.1 ± 1.9%, respectively. The agents did not affect the cytokineinduced augmentation of class I antigens. The inhibition of class II molecule expression may at least partly account for the preventive effect of niacinamide on autoimmune-associated α-cell damage in NOD mice.
Population-Based Study of Impaired Glucose Tolerance and Type II Diabetes in Wadena, Minnesota
Authors: French L Ronald , Boen James R , Martinez Anita M , Bushhouse Sally A , Sprafka J Michael , Goetz Frederick C
Published: September 2013

The Wadena City Health Study was undertaken to assess the nature of type II (non-insulin-dependent) diabetes and its relationship to aging. This article reports the study methodology and prevalence estimates for type II diabetes and impaired glucose tolerance (IGT) for the adult population of Wadena, Minnesota. The sampling frame for the study included all known diabetic individuals and all other residents based on a complete citywide census of residents ≥20yr of age. A stratified random sample that included three stratifying factors (age [20–39, 40–59, ≥60 yr], sex, and self-reported weekly use of any prescribed medication was drawn from the other residents). The study protocol required diet preparation and two full mornings of testing. Data collected included height, weight, and blood pressure measurements and both a personal interview and a medications questionnaire. A 75-g oral glucose tolerance test (OGTT) and a test with a standard liquid meal (Ensure-Plus challenge test [EPCT], Ross) were done on two mornings, with the order of testing randomly assigned. Clinical tests included one-time samples for hemoglobin, glycosylated hemoglobin, plasma cholesterol, triglycerides, and lipoproteins. Blood samples for glucose and creatinine assays were taken during the OGTT; blood samples for glucose, free fatty acid, creatinine, and C-peptide were taken during the EPCT. Urine collections were performed for both challenge tests and assayed for C-peptide and creatinine. Seventy-one percent of the known diabetic subjects, and 65% of the stratified random sample participated in the study. The mean age of the oldest men and women in the stratified random sample was older for the nonparticipants. Otherwise, no systematic differences were observed between study participants and nonparticipants. Both National Diabetes Data Group (NDDG) and World Health Organization (WHO) criteria were used to clarify the current diabetes status of study participants. Age- and sex-standardized (1980 U.S. census) estimates of the prevalence of type II diabetes and glucose intolerance were calculated. Based on NDDG criteria, the prevalance of type II diabetes was 7.8%, and the prevalance of IGT was 5.3%. WHO criteria placed the prevalence of type II diabetes and IGT at 8.1 and 15.0%, respectively. The implications of the high total prevalence of hyperglycemia are discussed.
Characteristics and Mechanisms of High-Glucose–Induced Overexpression of Basement Membrane Components in Cultured Human Endothelial Cells
Authors: Cagliero Enrico , Roth Timothy , Roy Sayon , Lorenzi Mara
Published: September 2013

Growing evidence that high glucose may be a causative agent of the thickened vascular basement membranes that characterize diabetic microangiopathy prompted this investigation of the underlying mechanisms. When exposed to 30 mM glucose, 70% of 52 primary cultures of human endothelial cells, each derived from a single umbilical vein, showed increased levels of fibronectin (median 181% of control, range 104–549%) and collagen IV mRNA (175% of control, range 101–807%). The response of the two transcripts to high glucose was concordant in 77% of the 52 cultures studied (P = 0.01), required 5 days of exposure, and was accompanied by proportionally increased synthesis of the respective protein. Laminin B1 expression was also upregulated by high glucose, concordantly with that of fibronectin and collagen IV. Increased fibronectin and collagen IV mRNA levels resulted from increased gene transcription (median 183 and 236% of control, respectively) without evidence of translational regulation, were not triggered by hypertonicity or signals originating from the matrix, and were also induced by hexoses with limited (D-galactose) or no (L-glucose) access to metabolic pathways but capable of inducing nonenzymatic glycosylation. There was no amplification of the overexpressed genes. Thus, high glucose upregulates in a coordinated fashion the transcription of genes coding for basement membrane components through effects exerted intracellularly or at the cell-matrix boundary and modulated by individual characteristics of the target cells.
Use of In Vitro Clonogenic Assays to Differentiate Acquired From Genetic Causes of Insulin Resistance
Authors: Geffner Mitchell E , Bersch Noelle , Nakamoto Jon M , Scott Marilyn , Johnson Nancy B , Golde David W
Published: September 2013

Insulin resistance may be due directly to genetically programmed disorders of insulin action or acquired defects in which environmental factors influence insulin action. To address the issue of this distinction, we studied the ability of insulin to stimulate colony formation in primary cultures of erythroid progenitors (assumed to retain environmental influences) and immortalized T lymphocytes (presumed to reflect only genetic influences). Four patients with hyperinsulinemia and disturbed glucose metabolism were studied (2 patients with acanthosis nigricans, 1 of whom had circulating anti-insulin-receptor antibodies, 1 with partial lipodystrophy, and 1 with Cushing's syndrome). The mean colony-forming ability of their erythroid progenitor cells in response to insulin stimulation (≤1.6 pM) was significantly blunted compared with control cells (P < 0.05). The mean responsiveness of their immortalized T-lymphoblast cell lines to similar insulin concentrations was no different than that of control T-lymphocyte lines, consistent with an acquired cause for the observed insulin resistance in each case. A T-lymphocyte line from a patient with leprechaunism, however, showed no stimulation in response to physiological concentrations of insulin. With these same in vitro methodologies, there was normal T-lymphocyte line responsiveness to insulinlike growth factor I (IGF-I) or insulin concentrations >8.6 pM; both of these responses could be completely blocked by preincubation with an antibody to the IGF-I receptor. These findings suggest that, despite resistance to physiological levels of insulin, the high circulating insulin concentrations present in the serum of these patients could mediate unwanted tissue-specific growth through an intact IGF-I receptor-effector mechanism.
Effect of Alginate-Polylysine-Alginate Microencapsulation on In Vitro Insulin Release From Rat Pancreatic Islets
Authors: Fritschy Wilbert M , Wolters Gerrit H J , Schilfgaarde Reinout Van
Published: September 2013

We investigated the effect of alginate-polylysine-alginate microencapsulation on glucose-induced insulin secretion by rat islets. Applying the encapsulation method originally described by Lim, we found severely reduced in vitro insulin release (expressed as picomoles of insulin · 10 islets−1 · 45 min−1 when incubated in 16.5 mM glucose), because the insulin release with encapsulated islets was 1.42 ± 0.49 compared to 13.58 ± 0.80 with free control islets. This could not be explained by inadequate permeability of the capsule, because insulin release was also severely reduced (2.12 ± 0.61) when islets were subjected to the procedure but without the membrane-forming polylysine step. Therefore, islets were tested after having been subjected separately to each of the steps of the procedure. Insulin release was not affected by either alginate or CaCI2 but was severely reduced after prolonged suspension in saline or treatment with citrate. When saline and citrate were replaced by Ca2+-free Krebs-Ringer bicarbonate buffer (KRBB) and 1 mM EGTA, respectively, insulin release improved significantly both with complete and with incomplete (no polylysine step) encapsulation. This outcome was verified in a set of experiments run in parallel with islets derived from the same isolation procedure. Insulin release was 1.20 ± 0.23 from islets encapsulated with the method of Lim and 10.73 ± 1.04 from free control islets. With the modified procedure, insulin release was 9.17 ± 0.52 vs. 9.61 ± 1.27 for complete versus incomplete encapsulation, respectively. We conclude that Ca2+-free KRBB instead of saline and EGTA instead of citrate should be used to obtain an adequate insulin response from encapsulated islets and that the capsule membrane as such has no influence on glucose and insulin diffusion.
Crucial Role of Aldose Reductase Activity and Plasma Glucose Level in Sorbitol Accumulation in Erythrocytes From Diabetic Patients
Authors: Hamada Yoji , Kitoh Ryuzo , Raskin Philip
Published: September 2013

Increased sorbitol levels have been demonstrated in tissues of diabetic patients. Although tissue sorbitol levels correlate with plasma glucose levels, a large variability in sorbitol levels has been observed among diabetic patients with similar plasma glucose levels. This variability in tissue sorbitol levels may be due to differences in the activity of aldose reductase, the enzyme that converts glucose to sorbitol. In this study, we isolated aldose reductase from erythrocytes of 31 diabetic patients and 6 nondiabetic control subjects, measured its activity, and compared it to simultaneously measured erythrocyte sorbitol levels. The activity of erythrocyte aldose reductase was increased in diabetic patients compared with control subjects (28.1 ± 1.4 vs. 22.4 ± 1.7 nmol · min−1 · g−1 Hb, P < 0.05), but there was an ∼ threefold variation in aldose reductase activity among diabetic patients. Erythrocyte aldose reductase activity and fasting plasma glucose levels significantly correlated with the erythrocyte sorbitol level in all individuals (r = 0.48, P < 0.005 and r = 0.63, P < 0.005, respectively). The sorbitol level was higher in patients with high aldose reductase activity than in those who had low enzyme activity for any given level of glycemia. The sorbitol production rate calculated from Km and Vmax values showed a better correlation with the erythrocyte sorbitol level (r = 0.80, P < 0.005), and there was also a good correlation between the erythrocyte sorbitol level and the product of aldose reductase activity by plasma glucose level (r = 0.70, P < 0.005). We conclude that both aldose reductase activity and the ambient plasma glucose concentration are important determinants of the level of sorbitol that accumulates in tissues of diabetic patients.
Reduced Vitamin E and Increased Lipofuscin Products in Erythrocytes of Diabetic Rats
Authors: Jain Sushil K , Levine Steven N , Duett John , Hollier Becky
Published: September 2013

Vitamin E deficiency in erythrocytes causes decreased cell survival, hypercoagulability, and increased adhesiveness to the endothelium. Similar abnormalities are found in erythrocytes of the diabetic population. This study examines the effect of diabetes on vitamin E and lipofuscin products (aging pigments) in erythrocytes of streptozocin-induced diabetic rats. Controls were injected with buffer alone, and a subgroup consisting of insulin-treated diabetic rats were injected daily with insulin for 2 mo. Mean ± SD vitamin E levels were 23.2 ± 4.9, 19.4 ± 3.2, and 25.9 ± 2.5 nmol/μmol phospholipid. Lipid fluorescence values (relative values/phospholipid) were 11.1 ± 1.9, 14.1 ± 2.6, and 11.9 ± 1.8 (excitation/emission 360/440 nm) in control, diabetic, and insulin-treated diabetic rats, respectively. Differences in vitamin E and lipofuscin products were significant between all control and diabetic groups and diabetic and insulin-treated diabetic groups. Reduction in vitamin E and increases in lipofuscin products in diabetic rats were significant even when values were expressed per micromole Hb or per 100 ml erythrocytes. This study demonstrates that hyperglycemia significantly reduces vitamin E and increases lipofuscin products in erythrocytes of diabetic rats. These effects were prevented with insulin treatment.
Diabetic Environment and Genetic Predisposition as Causes of Congenital Malformations in NOD Mouse Embryos
Authors: Otani Hiroki , Tanaka Osamu , Tatewaki Reiko , Naora Hiroyuki , Yoneyama Tsunao
Published: September 2013

Congenital malformations such as neural tube defects and a kinky or waved vertebral column were observed at higher incidence in embryos from nonobese diabetic (NOD) female mice with overt diabetes (NOD-D; 40.3%, P < 0.005) or without overt diabetes (NOD-N; 8.4%, P < 0.05) than in control Institute of Cancer Research (ICR) mouse embryos (1%) at day 13 of gestation. In vivo and in vitro preimplantation development of NOD-N, NOD-D, and ICR embryos did not differ in rate of development, size, or morphology. Embryos cultured from one-cell to early blastocyst stage were mutually transferred to uterine horns of pseudopregnant females between NOD-D and ICR mice and examined at day 13 of gestation. There were significant decreases in ratios of implantation and of viable embryos in ICR embryos transferred to NOD-D recipients (52%, P < 0.001 and 14%, P < 0.001, respectively) compared with those ratios in ICR embryos transferred to ICR uteri (79.2 and 56.2%) or those in NOD-D embryos transferred to ICR uteri (70.3 and 33.1%). Furthermore, 18 of 45 viable ICR embryos transferred to NOD-D dams had malformations, whereas there were no malformations in 73 viable ICR embryos transferred to ICR recipients, suggesting deleterious effects of maternal diabetic environment to embryos. On the other hand, 8 of 58 viable NOD-D embryos that were cultured in vitro and transferred to ICR uteri had malformations such as neural tube defects. This study suggests that both the presence of diabetes in the mother and a distinct genetic predisposition in embryos are involved as causes of the high incidence of congenital malformations in NOD-D embryos
Direct Vital Microscopic Study of Defective Leukocyte-Endothelial Interaction in Diabetes Mellitus
Authors: Fortes Zuleica B , Farsky Sandra P , Oliveira Maria A , Garcia-Leme Joāo
Published: September 2013

The number of leukocytes rolling along the venular endothelium of the vascular network of the internal spermatic fascia was determined in nondiabetic control rats and diabetic rats with television microscopy. A marked decrease in the number of rolling cells was observed in animals rendered diabetic by the injection of alloxan 10, 30, or 180 days before relative to matching controls. Blood leukocyte counts, however, were equivalent in both control and diabetic rats. Under the influence of a local inflammatory stimulus, cells emerged into the perivascular tissue in control animals, and this was accompanied by a reduction in the number of rolling leukocytes. In diabetic rats, the number of rolling leukocytes remained unaltered, and only a few cells accumulated in the connective tissue adjacent to the vessel. Reversal of the defective leukocyte-endothelial interaction was attained by treatment of diabetic animals with insulin. Inhibitors of arachidonic acid metabolism were ineffective to improve leukocyte-endothelial interactions in diabetic animals. Control rats injected intravenously with lyophilized plasma constituents, obtained after dialysis of diabetic rat plasma with 12,000-M retention dialysis tubing, behaved as diabetic animals in that they exhibited a reduced number of leukocytes rolling along the venular endothelium. In contrast, material obtained from control rat plasma produced no effect. Heating of active samples for 1 h at 56°C degrees C resulted in the complete loss of the inhibitory effect. We conclude that a substance or substances present in diabetic plasma induce a defective leukocyte-endothelial interaction that further impairs resistance to infection.
Downregulation of Protein Kinase C and Insulin-Stimulated 2-Deoxyglucose Uptake in Rat Adipocytes by Phorbol Esters, Glucose, and Insulin
Authors: Ishizuka Tatsuo , Cooper Denise R , Arnold Thomas , Hernandez Herman , Farese Robert V
Published: September 2013

Phorbol esters translocatively activate and subsequently downregulate protein kinase C and insulin-stimulated glucose uptake in rat adipocytes. This study examined the possibility that other translocative activators of protein kinase C in rat adipocytes, e.g., insulin and glucose, provoke similar downregulating effects. Pretreatment of rat adipocytes for 20–24 h with phorbol esters, 3 nM insulin, 20 mM glucose, or 3 nM insulin plus 20 mM glucose resulted in concomitant decreases in protein kinase C and insulin–stimulated (or phorbol ester–stimulated) [3H]-2-deoxyglucose uptake. Downregulating effects of glucose on protein kinase C and insulin-stimulated [3H]-2-deoxyglucose uptake were also evident within 30 min in adipocytes freshly incubated in medium containing 5–20 mM, rather than 0, glucose. These findings confirm that protein kinase C is required during insulin-stimulated glucose uptake and raise the possibility that downregulation of protein kinase C by continued translocative activation of the enzyme may contribute (along with other factors) to impaired responsiveness of the glucose transport system after prolonged insulin and/or glucose treatment.
Activation by Vanadate of Glycolysis in Hepatocytes From Diabetic Rats
Authors: Rodríguez-Gil Joan E , Gómez-Foix Anna M , Fillat Cristina , Bosch Fàtima , Guinovart Joan J
Published: September 2013

In hepatocytes from starved streptozocin-induced diabetic rats, vanadate increases the glycolytic flux because it raises the levels of fructose-2,6-bisphosphate (Fru-2,6-P2), the main regulatory metabolite of this pathway. This effect of vanadate on Fru-2,6-P2 levels is time and dose dependent, and it remains in cells incubated in a calcium-depleted medium. Vanadate is also able to counteract the decrease on Fru-2,6-P2 levels produced by glucagon, colforsin, or exogenous cAMP. However, vanadate does not modify 6-phosphofructo-2-kinase and pyruvate kinase activities, but it does counteract the inactivation of these enzymes induced by glucagon. Likewise, Fru-2,6-P2ase activity is also not affected by vanadate. In addition, vanadate is able to increase the production of both lactate and CO2 in hepatocytes from streptozocin-induced diabetic rats incubated in the presence of glucose in the medium. Vanadate behaves as a glycolytic effector in these cells, and this effect may be related to its ability to normalize blood glucose levels in diabetic animals.
New Inbred Strain of Long-Evans Tokushima Lean Rats With IDDM Without Lymphopenia
Authors: Kawano Kazuya , Hirashima Tsukasa , Mori Shigehito , Saitoh Yuichi , Kurosumi Masao , Natori Takashi
Published: September 2013

Spontaneously diabetic rats with remarkable polyuria, polyphagia, and polydipsia werediscovered in 1983 in an outbred colony of Long-Evans rats purchased from Charles River Canada in 1982. They have since been maintained at the Tokushima Research Institute (OtsukaPharmaceutical, Tokushima, Japan). A strain of rats (Long-Evans Tokushima Lean [LETL]) with diabetes was bred from these rats. The characteristic features of the disease in LETL rats are 1) sudden onset of polyuria, polyphagia, hyperglycemia, andweight loss; 2) no sex differences in the rate of onset or severity; 3) lymphocyte infiltration into islets followed by destruction of β-cells and disappearance of lymphocytes at the onset of diabetes; 4) no significant T lymphopenia; 5) lymphocyte infiltration into the salivary glands and lacrimal glands; and 6) at least two recessive genes involved in the pathogenesis of insulitis, one of which is closely linked with RT1u. These characteristics closely resemble those of human insulin-dependent diabetes mellitus (IDDM). Results suggest that the LETL rat is a useful animal model for analysisof genetic and immunologic factors relating to the pathogenesis of human IDDM.
Platelet Adhesion and Aggregate Formation in Type I Diabetes Under Flow Conditions
Authors: Nievelstein Patricia F E M , Sixma Jan J , Ottenhof-Rovers Mieke , Wynne Herman J , De Groot Philip G , Banga Jan Dirk
Published: September 2013

To study platelet activation as a phenomenon that may precede development of angiopathy in diabetes mellitus, we compared platelet adhesion and thrombus formation in a flow system with blood from insulin-dependent (type I) diabetic subjects with and without macroangiopathy and age- and sex-matched control subjects. Adhesion and thrombus formation on matrix of cultured human endothelial cells (ECM) and adhesion on matrix of human fibroblasts (FBM) were studied after exposure to flowing blood at shear rates of 300 and 1300 s−1 and exposure times of 1, 3, 5, and 10 min (and 20 min in adhesion experiments). Blood was anticoagulated with trisodium citrate (1:10 vol/vol, 110 mM) or low-molecular-weight heparin ([LMWH] 20 U/ml). Endothelialcell cultures were either unstimulated or stimulated with 4β-phorbol 12-myristate 13-acetate (PMA) 16 h before isolating their matrix. Platelet adhesion on ECM and FBM in citrated and LMWH-anticoagulated blood was identical in diabetic patients and controlsubjects, with comparable increases of adhesion with increasing perfusion times. Platelet aggregate formation on ECM of PMA-stimulated cells with LMWH-anticoagulated blood was similar in diabetic patients, whether macroangiopathy was present, compared with controlsubjects. Fibrin deposition and fibrinopeptide A generation during perfusion were comparable in diabetic and control subjects. Platelet thromboxane B2 formation after stimulation with arachidonic acid was increased in diabetic patients without macroangiopathy compared with age- and sex-matched control subjects. In the perfusion system, thepatterns of platelet adhesion and aggregate formation on extracellular matrix in flowingblood of diabetic patients (with or without macroangiopathy), and healthy age- and sex-matched control subjects followed a similar pattern. An increase in platelet–vessel wall interaction in diabetes mellitus was not detected, even in the presence of macroangiopathy.
Altered Neuropeptide Y Concentrations in Specific Hypothalamic Regions of Obese (fa/fa) Zucker Rats: Possible Relationship to Obesity and Neuroendocrine Disturbances
Authors: McKibbin Pauline E , Cotton Stephen J , McMillan Sheila , Holloway Brian , Mayers Rachel , McCarthy H David , Williams Gareth
Published: September 2013

Neuropeptide Y (NPY) concentrations were measured by radioimmunoassay in eight microdissected hypothalamic regions of obese (fa/fa) and lean (Fa/?) Zucker rats. Freely fed obese rats showed significant (40–100%) increases in NPY concentrations in several regions, notably the paraventricular, ventromedial, and dorsomedial nuclei and the arcuate nucleus/median eminence, compared with lean rats. Hypothalamic NPY concentrations were not affected in either obese or lean rats by food restriction, which caused 25% weight loss over 3 wk. Refeeding to initial weight significantly increased NPY levels in the ventromedial and dorsomedial nuclei in lean rats but did not significantly alter NPY concentrations in any hypothalamic region in obese rats. These observations indicate fundamental differences in the regulation of hypothalamic NPY between obese and lean Zucker rats. NPY injected into the paraventricular nucleus and other regions causes hyperphagia, obesity, and increased secretion of insulin, glucagon, ACTH, and corticosterone. These behavioral and neuroendocrine abnormalities all occur in the obese Zucker syndrome and may be due to increased NPY-ergic activity in the hypothalamus.
Prevention by Protein Kinase C Inhibitors of Glucose-Induced Insulin-Receptor Tyrosine Kinase Resistance in Rat Fat Cells
Authors: Müller H K , Kellerer M , Ermel B , Mühlhöfer A , Obermaier-Kusser B , Vogt B , Häring H U
Published: September 2013

Hyperglycemia causes insulin-receptor kinase (IRK) resistance in fat cells. We characterized the mechanism of IRK inhibition and studied whether it is the consequence of a glucose-induced stimulation of protein kinase C (PKC). Fat cells were incubated for 1 or 12 h in culture medium containing either a low- (5-mM) or high- (25-mM) glucose concentration. IRK was isolated, insulin binding was determined, and autophosphorylation was studied in vitro with [γ-32P]ATP or was determined by Western blotting with anti-phosphotyrosine antibodies. Substrate phosphorylation was investigated with the artificial substrate poly(Glu80-Tyr20). Partially purified insulin receptor from rat fat cells, which were cultured under high-glucose conditions for 1 or 12 h, showed no alteration of insulin binding but a reduced insulin effecton autophosphorylation (30 ± 7% of control) and poly(Glu80-Tyr20) phosphorylation (55.5 ± 9% of control). Lineweaver-Burk plots of the enzyme kinetics revealed, beside a reduced Vmax, and increased KM (from 30 μM to 80 μM) for ATP of IRK from high-glucose–treated cells. Because a similar inhibition pattern was earlier found for IRK from fat cells afteracute phorbol ester stimulation, we investigated whether activation of PKC might be the cause of the reduced IRK activity. We isolated PKC from the cytosol and the membrane fraction of high- and low-glucose fat cells and determined the diacylglycerol- and phospholipid-stimulated PKC activity toward the substrate histone. There was no significant change of cytosolic PKC; however, membrane-associated PKC activity was increased in high-glucose–treated cells. To evaluate whether the activation of PKC causes the inhibitors (H 7, staurosrine, and polymyxin B) and tested whether the effect of hyperglycemia was stillpresent when fat cells were pretreated with phorbolester (tetradecanoylphorbol acetate) for 24 h. Indeed, H 7, staurosporine, and polymyxin B blocked the inhibitory effect of hyperglycemia on IRK. Furthermore, in cells treated for 24 h with tetradecanoylphorhol acetate, no inhibitory effect of hyperglycemia was observed. This and the effect of the PKC inhibitors are consistent with a causal relationship between IRK inhibition and PKC activation
Regulation of Glucose Metabolism in Livers and Kidneys of NOD Mice
Authors: Sochor Milena , Kunjara Sirilaksana , Zaheer Baquer Najma , McLean Patricia
Published: September 2013

Measurements were made of the levels of metabolic intermediates and activities of enzymes of the glycolytic route, pentose phosphate pathway, and polyol pathway in livers and kidneys of NOD mice. A 34% decrease in UDP-glucose, a 40% decrease in glucose-6-phosphate (G6P) and fructose-6-phosphate, and a 75% decrease in fructose-2,6-bisphosphate (F2,6P) were found in the livers of NOD mice. The fall in the level of F2,6P (the important regulator of glycolysis) is accompanied by a 20% reduction in the activity of phosphofructokinase. These changes are in agreement with previously reported liver depletion of glycogen and reduced synthesis of proteins and nucleic acids in the diabetic state. In the kidney, the increase in hexokinase activity is consistent with increased levels of G6P and glycogen content of kidney in diabetes. The decreased level of phosphoribosyl pyrophosphate was reported to be a regulator of kidney growth in the initial period of diabetes but can still be found in NOD mice 6 wk after development of hyperglycemia. The reported changes are similar to those seen in alloxan- or streptozocin-induced diabetic animals, but certain changes are more marked in NOD mice, especially those directed to increase nucleic acid and protein synthesis in the diabetic kidney.
Signal Peptide–Length Variation in Human Apolipoprotein B Gene: Molecular Characteristics and Association with Plasma Glucose Levels
Authors: Boerwinkle Eric , Chen San-Hwan , Visvikis Sophia , Hanis Craig L , Siest Gerard , Chan Lawrence
Published: September 2013

We studied the molecular characteristics of three naturally occurring variants in the human apolipoprotein B (apoB) signal peptide, their frequencies in non-insulin-dependent diabetic and random populations, and their association with several measures of lipid and carbohydrate metabolism. In a random sample of 197 French whites, there were two common alleles, 5′βSP-24 and 5′βSP-27, with frequencies of 0.35 and 0.65, respectively. In a random sample of 181 Mexican Americans, there was an additional allele, 5′βSP-29, with a frequency of 0.03. DNA sequence analysis indicated that the signal peptide alleles consisted of the following: 5′βSP-29 encoded 29 amino acids in the signal peptide containing two copies of the sequence CTG GCG CTG encoding Leu-Ala-Leu and a consecutive run of eight Leu-encoding codons; 5′βSP-27 encoded 27 amino acids with a run of only six Leu codons; 5′βSP-24 encoded 24 amino acids and contained a single copy of CTG GCG CTG and a run of six Leu codons. In the sample of French whites, average apoAI and glucose levels were significantly different among signal peptide genotypes. 5′βSP-24/24 homozygotes had higher apoAI levels than the two other signal peptide genotypes (1.59 vs. 1.42 g/L, respectively). Heterozygous 5′βSP-24/27 individuals had the highest glucose levels. In the random sample of Mexican Americans, average glucose levels were also significantly different among signal peptide genotypes. However, the rank order of average glucose levels was not the same between the two samples. In the sample of Mexican Americans, glucose levels were significantly elevated (6.14 mM) in the 5′βSP-24/24 homozygotes relative to the other genotypes. Correspondingly, average glycosylated hemoglobin levels were increased and C-peptide levels were decreased in homozygous 5′βSP-24/24 individuals. There were no significant differences in the frequency of the three signal peptide alleles between the random sample of Mexican Americans and a sample of 203 non-insulin-dependent diabetic Mexican Americans. The cause of the association (e.g., chance, linkage-phase disequilibrium, causation) between signal peptide–length variation and plasma glucose levels is not known.