bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Histocompatibility Antigens in Transplantation of Isolated Islets of Langerhans in the Rat
Authors: Hiller Wolfgang F A , Steiniger Birte , Klempnauer Jürgen
Published: September 2013

In a model of congenic and intra-MHC recombinant rat strains, the differential role of various histocompatibility antigens in renal subcapsular transplantation of purified islets of Langerhans isevaluated. Class I MHC antigens of the RT1.A region, expressed on the endocrine cells of the islets themselves, do not induce graft rejection on their own. MHC class I antigens as encoded by the RT1.C region do not induce rejection either. MHC class II antigens as encoded by the RT1.B/D region are not expressed on the endocrine pancreas, not even during rejection. Although interstitial dendritic cells situated within the islets expess these antigens, an isolated RT1. B/D incompatibility of islets is associated with prolonged survival in contrast to rapid rejection of fully MHC-mismatched grafts. Unlike other organs, islets matched for all MHC antigens, but incompatible at minor histocompatibility antigens, undergo rejection early after transplantation.
Repair of Pancreatic β-cells: A Relevant Phenomenon in Early IDDM?
Authors: Eizirik Décio L , Sandler Stellan , Palmer Jerry P
Published: September 2013

Most studies dealing with the pathogenesis of IDDM have emphasized the immune assault against β-cells. In this perspective, we review the data that suggest that the β-cell destruction of IDDM depends on a balance between β-cell damage and repair. The progressive β-cell damage leading to IDDM seems to follow markedly different temporal courses in individual patients. Some individuals at high risk for developing IDDM, and presenting with impaired β-cell function, appear to recover β-cell function when followed prospectively. Moreover, after the clinical onset of IDDM, most patients experience a transitory period of improved insulin secretion. In vitro and in vivo experimental data suggest that β-cells are indeed able to repair themselves after damage. Dispersed β-cells or whole islets can survive and regain their function after a toxic assault. Furthermore, the abnormal insulin release and glucose oxidation of islets isolated from NOD mice during the prediabetic period is completely restored after 1 wk in tissue culture. Finally, treatment of NOD mice with monoclonal antibodies directed against infiltrating T-cells reverses the altered glucose metabolism of β-cells. Note that β-cell repair after exposure to different toxic agents can be enhanced both in vivo and in vitro. Potential enhancers of β-cell repair are nicotinamide, glucose, protein-rich diets, and branched chain amino acids. A basic question that remains to be answered is the nature of the repair mechanisms triggered by β-cells. Some of the β-cell responses to injury include expression of heat shock proteins 32,000, 65,000, 70,000, and 90,000 Mr, activation of the enzyme poly(ADP-ribose) polymerase, induction of the growth arrest and DNA damage inducible genes 45 and 153, and enhanced manganese superoxide dismutase activity. The heat shock protein 70 is of special interest because it has been shown to be both induced by interleukin-1 and protective of β-cells against the deleterious effects of this cytokine. The findings mentioned above suggest that repair mechanisms activated after β-cell injury are an important component of the IDDM disease process. It is conceivable that a detailed characterization of the cellular and molecular mechanisms involved in β-cell repair may contribute to the development of early preventive therapy for IDDM.
Metabolism of des(64,65)-Human Proinsulin in the Rat: Evidence for the Proteolytic Processing to Insulin
Authors: Wroblewski Victor J , Masnyk Michael , Kaiser Raymond E
Published: September 2013

The metabolism of des(64,65)-human proinsulin was examined in rats after subcutaneous administration. Profiles of circulating insulin-like immunoreactivity in rat plasma 25 min after subcutaneous administration were evaluated by anion exchange fast protein liquid chromatography and reversed-phase high-performance liquid chromatography. Both techniques indicated the presence of circulating immunoreactivity having retention characteristics of human insulin. This metabolite peak comprised 5–10% of circulating immunoreactivity; the remainder had retention characteristics of des(64,65)-human proinsulin. The peaks of immunoreactive material were isolated and their structure determined using reversed-phase high-performance liquid chromatography and electrospray ionization mass spectrometry. The major circulating component co-eluted with des(64,65)-human proinsulin and had an identical mass spectrum. Two circulating metabolites were identified. These metabolites co-eluted by reversed-phase high-performance liquid chromatography with human insulin and diarginyl(B31,32)-human insulin and had mass spectra identical to the standard compounds. The data indicate proteolytic processing of des(64,65)-human proinsulin involves an initial tryptic cleavage at the carboxy side of ArgB32, with the formation of human insulin by the subsequent action of a carboxypeptidase to remove the ArgB31-ArgB32 dipeptide from diarginyl(B31,32)-human insulin. The results suggest that some of the pharmacological activity of des(64,65)-human proinsulin may be mediated in part by circulating insulin-like metabolites.
Impaired Vasodilator Response to Atrial Natriuretic Factor in IDDM
Authors: Smits Paul , Hersbach Ferry M R J , Jansen Tim L T A , Thien Theo , Lutterman Jos A
Published: September 2013

Diabetes mellitus has been associated with both elevated plasma concentrations of the natriuretic and vasorelaxant hormone atrial natriuretic factor and with a reduced natriuretic response to this hormone. We now hypothesize that the vasodilator response to atrial natriuretic factor is attenuated in IDDM. Forearm vasodilator responses to the infusion of six increasing dosages of atrial natriuretic factor into the brachial artery were registered by venous occlusion strain gauge plethysmography in 10 patients with uncomplicated IDDM and in 10 age-, sex-, and weight-matched control subjects. Baseline levels of blood pressure, forearm blood flow, and plasma concentrations of atrial natriuretic factor were not different between control subjects and patients with diabetes. In control subjects, atrial natriuretic factor induced a percentage fall in the forearm vascular resistance of –29 ± 5% at the lowest to –72 ± 4% at the highest infusion rate. In patients with diabetes this fall was significantly attenuated, measuring –2 ± 7 and –45 ± 4%, respectively, (P < 0.001 vs. control subjects). During infusion of atrial natriuretic factor into the brachial artery, the calculated regional production of cGMP (second messenger of atrial natriuretic factor) increased from 1.2 ± 1.1 to 22.8 ± 4.8 pmol.min−1 × 100 ml−1 in the control subjects, whereas hardly any change occurred in the patients with diabetes (from –2.1 ± 1.2 to 2.9 ± 4.7 pmol.min−1 · 100 ml−1). Furthermore, both control and diabetic subjects demonstrated an equal forearm vasodilator response to increasing infusion rates of the control vasodilator sodium nitroprusside. We conclude that uncomplicated IDDM is associated with a specific reduction in the vascular responsiveness to atrial natriuretic factor.
Regulation of Islet Amyloid Polypeptide in Human Pancreatic Islets
Authors: Novials Anna , Sarri Yolanda , Casamitjana Roser , Rivera Francisca , Gomis Ramon
Published: September 2013

This study investigated the effect of glucose on islet amyloid polypeptide secretion, content, and mRNA synthesis of human pancreatic islets. The release of islet amyloid polypeptide from fresh isolated islets in response to glucose was parallel to that of insulin. The islet amyloid polypeptide-to-insulin molar ratios in response to 5.5 and 16.7 mM glucose were 1:16 and 1:15 respectively. Islets were cultured for 1 and 7 days at two different glucose concentrations (5.5 and 16.7 mM). The islet amyloid polypeptide response to the 1-day culture was similar to that of the fresh islets; however, after the 7-day culture the islet amyloid polypeptide and insulin secretory responses to glucose were dissociated. The insulin response of islets to a high-glucose stimulus was significantly (P < 0.001) increased, whereas the islet amyloid polypeptide response of islets to the same stimulus was blunted. The IAPP content was > insulin content in a molar ratio (1:50 to 1:30) after long exposure of islets to concentrations of high glucose even though the increase was significant for both peptides (P < 0.005). Northern blot analysis of each cultured condition showed an increase of both mRNA IAPP and insulin signals after exposure of islets at 16.7 mM glucose, the maximum mRNA expression being after long exposure to high-glucose concentrations. Quantification of both signals by densitometry showed a greater increase for islet amyloid polypeptide than for insulin. These findings suggest that IAPP can be accumulated in beta-cells after long exposure of human islets to high-glucose concentrations, because glucose increases IAPP synthesis but not secretion. This may be important for understanding the factors involved in the amyloidogenicity of islet amyloid polypeptide and consequently in the pathogenesis of NIDDM.
Metabolic Consequences of Sustained Suppression of Free Fatty Acids by Acipimox in Patients With NIDDM
Authors: Saloranta Carola , Taskinen Marja-Riitta , Widén Elisabeth , Härkönen Matti , Melander Arne , Groop Leif
Published: September 2013

To examine whether overnight suppression of free fatty acid levels reduces hepatic glucose production, 20 NIDDM patients were given a slow-release formulation of the antilipolytic agent acipimox, in a double-blind crossover manner at bedtime for 4 wk. During acipimox treatment, serum free fatty acid concentrations were suppressed between 2400 and 0600 by 64% (P < 0.001), but no reduction in hepatic glucose production was observed (2.16 ± 0.16 vs. 2.23 ± 0.16 mg · kg−1 · min−1, acipimox vs. placebo). In contrast, from 0800 to 2000 a sustained 50% rise occurred in serum free fatty acids (P < 0.001). As a consequence, the 24-h area under the free fatty acid curve was similar during both treatment periods. In the morning, the rise in free fatty acid concentration occurred despite identical serum acipimox concentrations as those measured at midnight, when free fatty acid levels were suppressed. Although energy expenditure was higher (P < 0.05) during periods of elevated free fatty acid levels, the sums of energy expenditure measured in the morning and in the evening were similar during the acipimox and placebo periods. To exclude that the free fatty acid rise was caused by administration of acipimox only once at bedtime, additional experiments were performed administering acipimox every 2 h for 4 days. Despite similar acipimox concentration on day 1 and day 4 of this frequent dosing regimen, the free fatty acid concentrations were significantly higher on day 4 compared with day 1 (P < 0.01). In conclusion, under these circumstances overnight lowering of serum free fatty acid by antilipolytic treatment does not reduce hepatic glucose production in patients with NIDDM. Instead, it results in a sustained daytime rise in free fatty acid, leading to unchanged 24-h free fatty acid levels. This compensatory free fatty acid rise may be necessary to maintain energy production unchanged. Long-term studies are required to answer the question whether it is possible to inhibit the appearance of a major energy substrate as free fatty acid during chronic therapy in patients with NIDDM.
Complement Lytic Activity Has No Role in the Pathogenesis of Autoimmune Diabetes in NOD Mice
Authors: Baxter Alan Geogrge , Cooke Anne
Published: September 2013

The NOD mouse is widely used as a model of organ-specific autoimmunity because it develops specific autoimmune destruction of pancreatic β-cells. Although it is clear that T-cells and monocytes are necessary for β-cell destruction, humoral factors, such as antibodies and complement, may also contribute to tissue damage. Attempts to cure diabetes in experimental models by immunoisolation of transplanted islets has raised the need to protect the islets from the relatively small components of the complement cascade. In this study, we report that NOD mice have no complement lytic activity and that the exclusion of complement is unnecessary in this model. Sera from young NOD mice were unable to lyse sheep red blood cells coated with rabbit antibody. Lytic activity of NOD sera was reconstituted by mixing with C4-deficient CBA sera, but not C5-deficient DBA/2 sera, indicating the presence of C4, but the absence of C5 activity in NOD sera. Lytic activity of NOD sera could be reconstituted with human C5 electrofocused in polyacrylamide gel. The polymerase chain reaction was used to amplify fragments from genomic DNA corresponding to the region of Hc (the gene encoding C5) in DBA/2 mice, which carries a 2–base pair deletion responsible for the lack of C5 protein expression in these mice. DBA/2 and NOD mice from several colonies produced a fragment 2 bases shorter than that generated from the wild-type allele in BALB/c mice. We concluded that NOD mice have no complement lytic activity as they lack C5 because of a 2–base pair deletion in the coding region of He and that the NOD mouse is not an appropriate model to test the need for complement exclusion from immunoisolation chambers in the treatment of diabetes mellitus.
Effects of Insulin on Fatty Acid Reesterification in Healthy Subjects
Authors: Boden Guenther , Chen Xinhua , Desantis Richard A , Kendrick Zebulon
Published: September 2013

The effects of insulin on triacylglycerol/fatty acid cycling (fatty acid reesterification) were studied in 12 normal subjects during euglycemic hyperinsulinemia with the use of stable isotope dilution analysis ([2H5]glycerol and [1-13C]palmitate) in combination with indirect calorimetry. During basal conditions, 5.6 ± 0.6 μmol · kg−1 · min−1 of fatty acid were released of which ∼3.3 μmol · kg−1 · min−1 were oxidized and ∼2.2 mumol · kg−1 · min−1 were reesterified. A minority of the recycled fatty acid, (0.8 ± 0.4 μmol · kg−1 · min−1) never left the intracellular space before being reesterified (intracellular triacylglycerol/fatty acid cycling), whereas the majority (1.2 ± 0.4 μmol · kg−1 · min−1) were first released into the extracellular space and then reesterified in various organs (extracellular triacylglycerol/fatty acid cycling). In response to insulin, fatty acid release declined by 71% (from 5.6 ± 0.6 to 1.6 ± 0.2 μmol · kg−1 · min−1). Fatty acid oxidation (measured by indirect calorimetry) declined by 55% (from 3.3 ± 0.3 to 1.5 ± 0.3 μmol · kg−1 · min−1) and total triacylglycerol/fatty acid cycling was completely suppressed (from 2.2 to 0.0 μmol · kg−1 · min−1). Fatty acid release, oxidation, total and extracellular triacylglycerol/fatty acid cycling all correlated positively with plasma fatty acid concentrations. These data showed that insulin profoundly suppressed fatty acid release, oxidation as well as reesterification of those fatty acids that had entered the extracellular compartment. They suggested that physiological concentrations of insulin suppressed extracellular fatty acid reesterification primarily by inhibiting lipolysis.
The Pharmacodynamics and Activity of Intranasally Administered Insulin in Healthy Male Volunteers
Authors: Jacobs Maarten A J M , Schreuder Robien H , Jap-A-Joe Kenneth , Nauta Jos J , Andersen Peder M , Heine Robert J
Published: September 2013

The objective of the study was to assess the bioavailability and absorption dynamics of intranasal insulin (with di-decanoyl-alpha-phosphatidylcholine, DDPC, as absorption enhancer) in two potencies (U200 and U500). Toward this aim, the euglycemic clamp technique combined with somatostatin (100 μg/h) was used. Insulin was administered to 12 healthy males: 5 IU intravenously (20-min infusion); 10 IU subcutaneously; 50 IU (U200) and 50 IU, 100 IU, and 150 IU (U500) intranasally. Peak insulin levels (mean ± SD) were reached at 17.9 ± 2.6, 77.9 ± 38.3, 23.3 ± 5.4, 25.4 ± 8.4, 26.2 ± 8.3, and 27.5 ± 5.8 min, respectively. For the 50 IU dose, peak glucose requirements during the clamp and time to peak were not significantly different for U200 and U500: 548.8 ± 279.5 vs. 452.4 ± 232.9 mg/min and 41.3 ± 16.2 vs. 51.5 ± 29.9 min, respectively. Compared with intravenous insulin, the bioavailability calculated from the total area under the insulin curve was 13.2% (95% confidence interval 7.9, 21.9) and 8.8% (95% confidence interval 5.6, 13.8), and compared with subcutaneous insulin, the bioavailability was 14.8% (95% confidence interval 8.7, 25.2) and 9.9% (95% confidence interval 6.4, 15.4) for the U200 and U500 preparations, respectively. An apparent nonlinear dose-dependent relation was found for the U500 potency. The within-subject variability of the areas under the curves of plasma insulin after the administration of 100 IU was 43.6% (range 20.7–85.7). In conclusion, this nasal insulin preparation has promising absorption and action profiles in both potencies, which makes it suitable for further exploration of clinical applications.
Impaired Regulation of Hepatic Fructose-1,6-Bisphosphatase in the New Zealand Obese Mouse Model of NIDDM
Authors: Andrikopoulos Sofianos , Rosella Gennaro , Gaskin Elizabeth , Thorburn Anne , Kaczmarczyk Stan , Zajac Jeffrey D , Proietto Joseph
Published: September 2013

The New Zealand obese mouse, a model of NIDDM, is characterized by hyperglycemia, hyperinsulinemia, and hepatic and peripheral insulin resistance. The aim of this study was to investigate the biochemical basis of hepatic insulin resistance in NZO mice. Glycolytic and gluconeogenic enzyme activities were measured in fed and overnight fasted 19- to 20-wk-old NZO and control New Zealand chocolate mice. The NZO mice were twice as heavy as the NZC mice. The activity of the glycolytic enzymes glucokinase and pyruvate kinase was higher, whereas that of the gluconeogenic enzymes PEPCK and glucose-6-phosphatase was lower in fed and fasted NZO mice. These enzyme changes are consistent with a normal response to the hyperinsulinemia in NZO mice. In contrast, the activity of the third regulated gluconeogenic enzyme, fructose-1,6-bisphosphatase, was similar in fed and fasted NZO and NZC mice despite the higher insulin and glucose levels in the NZO mouse. This enzyme is primarily regulated by the powerful inhibitor fructose-2,6-bisphosphate. The levels of this metabolite were measured and found to be increased in both the fed and fasted states in the NZO mouse, suggesting that the activity of the bifunctional enzyme that regulates the level of inhibitor (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase) is normally regulated in the NZO mouse. We conclude that most insulin-responsive gluconeogenic and glycolytic enzymes are normally regulated in the NZO mouse, but an abnormality in the regulation of fructose-1,6-bisphosphatase may contribute to the increase hepatic glucose production in these mice.
Lymph Node T-Cells Do Not Optimally Transfer Diabetes in NOD Mice
Authors: Lepault Françoise , Faveeuw Christelle , Luan Jian Jian , Gagnerault Marie-Claude
Published: September 2013

The nonobese diabetic mouse in a model of spontaneous development of autoimmune type I diabetes. The disease can be induced in young, irradiated recipients by injecting splenic T-cells from diabetic donors. The adoptive transfer of diabetes requires the presence of both CD4+ and CD8+ splenic T-cell subsets. To test whether diabetogenic cells distribute in other lymphoid organs of diabetic mice, we first analyzed lymph node cells. Lymph node cells were much less efficient in transferring diabetes than splenocytes. This inefficacious transfer was not attributable to the absence of hematopoietic precursors or a lack of macrophages. Lymph node cells did not protect from the transfer of diabetes by splenocytes, indicating the absence of suppressor cells. Although CD8+ lymph node T-cells seemed functionally comparable to CD8+ splenocytes, CD4+ lymph node T-cells failed to cooperate with CD8+ splenocytes to transfer diabetes. Our study suggests that diabetogenic cells are not evenly distributed in the different lymphoid organs. This may reflect a differential migration pattern of pathogenic T-cells in this animal model.
Ala1048→Asp Mutation in the Kinase Domain of Insulin Receptor Causes Defective Kinase Activity and Insulin Resistance
Authors: Haruta Tetsuro , Takata Yasumitsu , Iwanishi Masanori , Maegawa Hiroshi , Imamura Takeshi , Egawa Katsuya , Itazu Takeharu , Kobayashi Masashi
Published: September 2013

We identified a heterozygous missense mutation that substituted aspartic acid (GAC) for alanine (GCC) at codon 1048 of the insulin receptor gene in a patient who displayed typical symptoms of Type A syndrome of insulin resistance. The proband's mother and younger brother were also found to be heterozygous for the mutation. We constructed the identified mutant insulin receptor cDNA by site-directed mutagenesis, transfected the mutant cDNA into COS 7 cells, and found that kinase activity of the mutant insulin receptors was markedly impaired. Ala1048 is located in the kinase domain of the insulin receptor β-subunit and is conserved in most of protein-tyrosine kinases. Besides, neighboring Glu1047 is invariant in all protein kinases and is thought to be involved in interaction with ATP. Photoaffinity labeling of the mutant insulin receptor with ATP analogue, 8-azido (α-32P)ATP was not influenced by the mutation, suggesting that the mutation did not inhibit ATP binding but possibly interfered with subsequent phosphoryl transfer. Insulin-stimulated phosphorylation of exogenous substrate by partially purified insulin receptors prepared from COS 7 cells that were cotransfected with wild-type and mutant insulin receptor cDNAs was markedly impaired, whereas autophosphorylation was decreased by ∼ 50% of wild-type receptors. These results indicated that the identified heterozygous substitution of Asp for Ala1048 in insulin receptor was responsible for insulin resistance of this patient.
Elevation of Factor Xla—α1-Antitrypsin Complex Levels in NIDDM Patients With Diabetic Nephropathy
Authors: Murakami Takashi , Komiyama Yutaka , Egawa Hiroshi , Murata Kenjiro
Published: September 2013

Excess activated FXIa in plasma indicates hypercoagulability in the early contact phase. We have already developed methods for detecting the hypercoagulable state in clinical samples by our ELISA for complexed FXIa and α1AT, which has been confirmed to be the predominant inhibitor of FXIa. Indiabetes, whether the activation of FXI is associated with the development of vascular complications remains unknown, although various hemostatic abnormalities have been described. We tested the complexed FXIa-α1AT level in 45 NIDDM patients, who were divided into three groups according to the development of diabetic nephropathy, as assessed by UAE. Normoalbuminuria was defined as UAE <15 μg/min, microalbuminuria as UAE in the range of 15–200 μg/min, and albuminuria as UAE >200 μg/min. In the patients as a whole, FXIa-α1AT and TAT levels were significantly increased compared with these levels in age-matched control subjects (17.3 ± 5.7 vs. 12.4 ± 2.4 ng/ml and 2.67 ± 1.23 vs. 1.93 ± 0.45 ng/ml, respectively). No significant difference was observed between FXIa-α1AT levels in the control subjects and in the normoalbuminuric group (13.0 ± 2.1 ng/ml; n = 19). However, in the microalbuminuric (17.9 ± 3.9 ng/ml; n = 16) and albuminuric (24.1 ± 5.4 ng/ml; n = 10) groups, FXIa-α1AT levels were significantly increased compared with those in the control and normoalbuminuric group. The TAT level was not correlated with FXIa-α1AT, and no significant differences in its levels were found among these diabetic groups. We agree with the widely held belief that diabetic nephropathy is strongly related to widespread microangiopathy, and suggest that the FXIa-α1AT level reflects vascular complications that occur concomitantly with such nephropathy. Therefore, we conclude that plasma FXIa-α1AT levels may be of potential pathophysiological or clinical importance for detecting early diabetic microangiopathy.
Severe Hypoglycemia and Intelligence in Adult Patients With Insulin-Treated Diabetes
Authors: Deary Ian J , Crawford John R , Hepburn David A , Langan Sarah J , Blackmore Louise M , Frier Brian M
Published: September 2013

The IQ scores (WAIS-R) of 100 patients with insulin-treated diabetes (aged 25–52 yr) were compared with those of 100 healthy control subjects who were matched to the diabetic patients for sex, age, education, and social class. The diabetic group had lower WAIS-R performance and verbal IQ scores than the control group (P = 0.017 and P = 0.033, respectively) after controlling for premorbid IQ. The extent of the difference was modest, representing ∼33% of an SD in IQ. When frequency of severe hypoglycemia was controlled for the difference in performance IQ between the diabetic patient group and the control group was abolished, whereas the difference between the groups in verbal IQ persisted. It is hypothesised that cumulative severe hypoglycemia might be the major factor in the slight performance IQ differences between diabetic patients and control subjects. The origin of the verbal IQ differences, although obscure, might be related to the social impact of the disorder.
CD8+ T-cells are Required for Adoptive Transfer of the BB Rat Diabetic Syndrome
Authors: Edouard Philippe , Hiserodt John C , Plamondon Caroline , Poussier Philippe
Published: September 2013

LGLs with NK activity account for the majority of BB rat PBLs expressing CD8, and it has been suggested that these LGL/NK cells are involved in the pathogenesis of the BB rat diabetic syndrome. By using a recently developed mouse MoAb, 3.2.3, specific for rat LGL, we demonstrate that BB and WF rat LGLs are phenotypically and functionally similar. To directly assess the role of LGLs in the development of diabetes in vivo, an adoptive transfer of T-cells to young LGL/NK cell-depleted diabetes-prone BB rats was performed. CD4+8− and CD4−8+ T-cells (> 98.5% pure), isolated from diabetic BB rats, were activated in vitro and injected into 30-day-old diabetes-prone BB rats. Recipients were either chronically injected with 3.2.3 (n = 15) or received an isotype-matched irrelevant MoAB (n = 14). Secondary lymphoid organs of 3.2.3-treated recipients contained < 0.1% 3.2.3+ lymphocytes, and this depletion was associated with a major decrease in the NK activity of their splenocytes. Despite this, the incidence of diabetes in 3.2.3-treated animals (40%) was not significantly different from that observed in control recipients (57%). Thus, the BB rat diabetic syndrome can be adoptively transferred in the absence of LGL/NK cells, suggesting that BB rat CD8+ T-cells are involved in the diabetogenic process. To assess the pathogenic role of CD8+ T-cells, we compared the incidence of diabetes in three groups of diabetes-prone BB recipients after injection of T-cells isolated from diabetic donors. In group 1, CD4−8+ and CD4+8− T-cells were injected into 3.2.3-treated recipients (n = 4), and in the two other groups, T-cells depleted of CD4−8+ T-cells were transferred into either 3.2.3-treated (n = 10, group 2) or 3.2.3 and anti-CD8-treated (n = 10, group 3) recipients. The incidence of diabetes in group 1 (75%) was significantly higher (P < 0.05) than in groups 2 (10%) and 3 (0%), demonstrating that donor CD4−8+ T-cells are required for the adoptive transfer of the BB rat xsdiabetic syndrome.
Prevention of Autoimmune Diabetes with Lymphotoxin in NOD Mice
Authors: Seino Hiroaki , Takahashi Kazuma , Satoh Jo , Ping Zhu Xiao , Sagara Mikio , Masuda Takayuki , Nobunaga Toshima , Funahashi Iwao , Kajikawa Tamio , Toyota Takayoshi
Published: September 2013

We have reported previously that chronic and systemic administration of a streptococcal preparation (OK-432), an inducer of TNF, or of recombinant hTNF prevented the development of IDDM in the two animal models of IDDM—NOD mice and BB rats. In this study, we examined the effect of LT, which is structurally and functionally related to TNF, on NOD mice with diabetes. The cumulative incidence of diabetes at 30 wk of age was 22 of 40 (55%) in nontreated female NOD mice and was 4 of 8 (50%; NS), 3 of 29 (10%; P < 0.001), and 0 of 8 (0%; P < 0.001) in female mice treated three times a week from 4 to 30 wk of age with 5, 50, or 500 U of recombinant hLT, respectively. Intensity of insulitis was slightly reduced in the long-term LT-treated mice. LT productivity by ConA-stimulated spleen cells was examined in vitro. Although no significant difference was found between NOD mice and the other mouse strains, female NOD mice were slightly but significantly (P < 0.01) lower producers of LT immunoreactivity than male NOD mice, the diabetes incidence of which is lower than that of females. The SMLR as a marker of normal immune response, which was reported to be impaired in autoimmune animals including NOD mice, was significantly lower in female than male NOD mice. However, the low SMLR in female NOD mice was significantly increased by the administration of LT, and the increase was mediated by the responder cells of the LT-treated mice. LT productivity by ConA-stimulated spleen cells was examined in vitro. Although no significant difference was found between NOD mice and the other mouse strains, female NOD mice were slightly but significantly (P < 0.01) lower producers of LT immunoreactivity than male NOD mice, the diabetes incidence of which is lower than that of females. The SMLR as a marker of normal immune response, which was reported to be impaired in autoimmune animals including NOD mice, was significantly lower in female than male NOD mice. However, the low SMLR in female NOD mice was significantly increased by the administration of LT, and the increase was mediated by the responder cells of the LT-treated mice. These results suggest that administration of LT prevented the development of IDDM in NOD mice by modulating autoimmunity.
Reduced Insulin Secretion by Repeated Low Doses of STZ Impairs Glucose Effectiveness but Does Not Induce Insulin Resistance in Dogs
Authors: Tobin Bonnie L , Finegood Diane T
Published: September 2013

To investigate the longitudinal relationship between progressive β-cell dysfunction and other parameters of glucose tolerance, we administered repeated low doses of STZ (10 mg/kg body wt) to dogs at 14-day intervals. STZ was discontinued after 10 doses (n = 4), the onset of fasting hyperglycemia (n = 1), or death (n = 1). Before the initial drug dose and 8 days after each treatment, an insulin-modified frequently sampled intravenous glucose tolerance test was performed to determine the integrated insulin response to glucose (0–19 min), insulin sensitivity, glucose effectiveness, and glucose tolerance. The integrated insulin response to glucose reached a nadir equal to 8% of pretreatment values by completion of the study. Despite this significant reduction in the insulin secretory response to glucose (P = 0.02), fasting plasma insulin, fasting plasma glucose, and insulin sensitivity remained constant throughout the study (P = 0.15, P = 0.71, and P = 0.5, respectively). SG, however, declined significantly below the pre-STZ treatment level in animals that received more than seven STZ doses (> 70 mg/kg STZ cumulatively, P < 0.03). In summary, when fasting normoglycemia is maintained, a 92% reduction in insulin secretory capacity and repeated low doses of STZ may alter glucose effectiveness but does not directly affect insulin sensitivity.
Enhanced Glucose Metabolism and Respiratory Burst in Peritoneal Macrophages From Spontaneously Diabetic BB Rats
Authors: Wu Guoyao , Marliss Errol B
Published: September 2013

Glucose metabolism and respiratory burst were studied in vitro in resident peritoneal macrophages from non-diabetes-prone BB, spontaneously diabetic BB, diabetes-prone BB, and STZ-induced diabetic BBn rats, in the presence or absence of phorbol myristate acetate plus ionomycin. Glycolysis and pentose phosphate pathway activity were increased in BBd compared with BBn cells. PMA plus IONO did not influence glycolysis in BBn macrophages and slightly decreased it in BBd macrophages. In contrast, PMA plus IONO increased the pentose phosphate pathway activity in BBn and BBd macrophages with a much greater increase in BBd cells. The release of O2− was greater in BBd than BBn cells; PMA plus IONO also induced a much greater release of O2− in BBd cells. H2O2 release was undetectable in unstimulated BBn cells, and stimulation by PMA plus IONO caused a small incremental release. In contrast, the release of H2O2 was measurable in unstimulated cells and further increased by 50% in BBd cells with PMA-plus-IONO stimulation. The release of O2− and H2O2 was increased in macrophages from 75-day-old BBdp rats but not in 50-day-old BBdp rats, compared with age-matched BBn rats. No differences were observed in either glucose metabolism or release of O2− and H2O2 between BBn and STZ-BBn cells in the absence or presence of PMA plus IONO. These data suggest that enhanced oxidative metabolism in BBd macrophages is unlikely to be attributable to diabetes per se. Furthermore, the results are consistent with prior in vivo immunological activation of BBd macrophages. Increased production of 02− and H2O2 from activated macrophages may be involved in the autoimmune destruction of β-cells that causes the diabetic syndrome.
No Effect of Deferoxamine Therapy on Glucose Homeostasis and Insulin Secretion in Individuals With NIDDM and Elevated Serum Ferritin
Authors: Redmon J Bruce , Pyzdrowski Kathryn L , Robertson R Paul
Published: September 2013

Deferoxamine has been proposed as a potentially important therapy for individuals with NIDDM and mild elevations in serum ferritin. Previously, iron chelation therapy with intravenous deferoxamine over a 5–13-wk period has been reported to normalize serum ferritin and markedly improve glycemic control. To confirm these results and to study potential beneficial effects of deferoxamine on insulin secretion, 9 individuals with NIDDM and elevated serum ferritin levels were treated twice weekly with deferoxamine infusion, following a previously described protocol. Although 8 of 9 subjects achieved normal or near-normal serum ferritin values after deferoxamine therapy, we found little evidence that it produced beneficial effects on glycemic control. Fasting glucose levels pre– and post-deferoxamine therapy were unchanged (11.6 ± 1.2 and 11.3 ± 1.5 mM, respectively, P = 0.80). GHb levels declined slightly after deferoxamine therapy (9.3 ± 0.7 vs. 8.8 ± 0.7%, P < 0.05); however, this effect was small and was not associated with elimination of or even substantial reduction in insulin or oral hypoglycemic therapy. Deferoxamine therapy did not significantly alter fasting insulin or C-peptide levels, nor stimulated insulin or C-peptide responses to intravenous arginine or glucose. During follow-up studies 1.5–8 mo after deferoxamine therapy, serum ferritin levels again were elevated in 5 of 8 subjects who showed an initial response. Thus, although deferoxamine therapy reduced serum ferritin levels in our subjects, we were unable to confirm a previous report that this effect was associated with any meaningful improvement in glycemic control or insulin secretion.
Abnormal Activation of Glycogen Synthesis in Fibroblasts from NIDDM Subjects: Evidence for an Abnormality Specific to Glucose Metabolism
Authors: Wells Ann M , Sutcliffe Iain C , Johnson Andrew B , Taylor Roy
Published: September 2013

To determine whether the tendency for NIDDM to run in families could relate to genetically determined defects in insulin stimulation of glycogen synthesis, skin fibroblasts from subjects with a strong family history of NIDDM were studied. Fibroblasts from nondiabetic subjects without any family history of NIDDM were studied as control subjects. The cells were studied after 7–16 passages in culture. Rates of glycogen synthesis were lower in fibroblasts from NIDDM subjects both basally and with maximal insulin stimulation (0.77 ± 0.11 vs. 0.46 ± 0.04 pmol.well−1 · h−1 [P < 0.02] and 1.49 ± 0.26 vs. 0.69 ± 0.05 pmol.well−1 · h−1 [P < 0.01]). Rates of glycogen synthesis were stimulated 1.9 ± 0.2-fold above basal in the control cells and 1.5 ± 0.1-fold above basal in the NIDDM cells (P < 0.02). Rates of [3H]thymidine uptake were similar in control and NIDDM fibroblasts (basal, 28.3 ± 2.8 vs. 39.2 ± 8.0; maximum, 50.9 ± 7.2 vs. 69.3 ± 16.9 dpm × 10−3, respectively). Rates of uptake increased similarly in control and NIDDM cells by 1.8 ± 0.1- and 1.7 ± 0.1-fold above basal. Maximum specific fibroblast insulin binding was similar for control and NIDDM subjects (194.0 ± 29.2 vs. 176.1 ± 24.9 fmol 125I-labeled insulin bound/mg protein respectively). The tyrosine kinase activity of insulin receptors isolated from the control and NIDDM fibroblasts was similar (basal, 135 ± 30 vs. 149 ± 33; submaximal, 153 ± 28 vs. 155 ± 30; and maximal insulin, 191 ± 45 vs. 213 ± 48 dpm.mg protein−1 · min−1). The observed abnormality was thus distal to the insulin receptor and did not involve all aspects of insulin signaling. These data provide evidence for a genetic influence on insulin control of glycogen synthesis in people with a strong family history of NIDDM.
Correction of Erythrocyte Deformability Defect in ALX-Induced Diabetic Rabbits After Treatment With Aminoguanidine
Authors: Brown Clinton D , Zhao Zhong H , De Alvaro Fernando , Chan Seewai , Friedman Eli A
Published: September 2013

To test whether treatment with aminoguanidine, a drug known to prevent cross-linking between glycated proteins, is effective in improving reduced erythrocyte deformability in diabetes, we studied a group (n = 6) of ALX-induced long-term (12.7 ± 2.2 mo of hyperglycemia) diabetic New Zealand white rabbits before and after 20 wk of treatment with aminoguanidine (100 mg.kg−1 · day−1). The key findings were as follows: 1) at 12 wk of treatment with aminoguanidine, mean erythrocyte deformability normalized and remained within the normal reference range throughout the period of aminoguanidine administration; 2) 10 wk after discontinuing aminoguanidine in a subset of diabetic rabbits, mean erythrocyte deformability deteriorated by ∼50%; 3) blood glucose and total GHb did not vary significantly during treatment with aminoguanidine nor after its discontinuation.
Tumor Necrosis Factor-α Prevents Rejection of Islet Xenografts (Rat to Mouse)
Authors: Gerasimidi Andriani , Sheehan Kathleen C , Schreiber Robert D , Lacy Paul E
Published: September 2013

The effect of in vivo administration of exogenous tumor necrosis factor-α on the survival of rat islet xenografts in STZ-induced diabetic mice was examined. Daily subcutaneous injections of purified recombinant murine TNF-α (3 μg/day) for 7 days after transplantation of islets prolonged the survival of the xenografts (26.7 ± 4.9 days) compared with controls (11.2 ± 1.1 days). Extension of the treatment from 0 to 59 days after transplantation produced an even greater prolongation of graft survival (53.7 ± 8.5 days). After cessation of treatment, an accelerated rejection of the grafts occurred. A most interesting finding was that delaying initiation of treatment until 3 days after transplantation and continuing until 60 days produced a remarkable prolongation of xenograft survival (mean survival time > 89.8 ± 17.5 days) with 2 recipients still normoglycemic at 124 days. Removal of the grafts at this time returned the 2 mice to a diabetic state. A second islet transplant from the same donor rat strain (Wistar-Furth) had an accelerated rejection, indicating that the long-term survival of the xenografts was not because of induction of tolerance. Delaying initiation of TNF treatment until 6 days after transplantation produced only a slight prolongation of survival (17.5 ± 1.2 days). Prolongation of islet xenograft survival also was obtained by continuous, subcutaneous delivery of TNF-α by a 7-day miniosmotic pump (3 μg/day). Lower daily doses of TNF-α (0.003, 0.3, and 1.0 μg) had no effect on graft survival. The findings indicate that daily subcutaneous injections of TNF-α will prevent rejection of rat islet xenografts, and if treatment is initiated early in the rejection process (3 days), then marked prolongation of survival continues even after cessation of treatment with TNF-α.
Physical Training Reverses Defect in Mitochondrial Energy Production in Heart of Chronically Diabetic Rats
Authors: Mokhtar Najat , Lavoie Jean-Pierre , Rousseau-Migneron Suzanne , Nadeau André
Published: September 2013

This study examined the impact of physical training on cardiac mitochondrial respiration of rats with chronic diabetes mellitus. Diabetes was induced by an intravenous injection of STZ (50 mg/kg) and only rats with a blood glucose level between 14 and 22 mM 1 wk later were kept in the protocol. Exercise training was conducted on a treadmill with a progressive 10-wk program. Animals were killed at the end of the training program, and mitochondria were isolated from ventricular tissue by differential centrifugation. Both state 3 respiration and oxidative phosphorylation rates were depressed significantly in the mitochondria of diabetic rats. These alterations were reversed completely to normal by physical training, without any significant changes in plasma glucose or insulin levels. The activity of ANT was not affected by diabetes or training. These results indicate that the depressed OPR present in isolated heart mitochondria from chronically diabetic rats is reversed to normal by physical training, apparently by mechanisms independent of blood glucose control. This correction in mitochondrial energy production may explain the improvement in cardiac function previously reported in trained diabetic rats.
Thoracic Duct Lymph: Relative Contribution From Splanchnic and Muscle Tissue
Authors: Steil Garry M , Meador Melissa A , Bergman Richard N
Published: September 2013

We have shown previously that thoracic duct lymph insulin dynamics are well correlated with tracer-determined whole-body glucose uptake and have suggested that thoracic duct lymph insulin is representative of insulin concentration in muscle interstitial fluid. However, thoracic duct lymph is comprised of interstitial fluid from all sub-thoracic tissue beds. To investigate the relative contribution of muscle interstitial fluid to total thoracic duct lymph flow, the distribution and elimination of [14C]inulin was investigated in eight experiments with conscious dogs. Both plasma and thoracic duct lymph were measured, and a three-compartment model that was hypothesized to consist of plasma, splanchnic interstitial fluid, and muscle interstitial fluid was identified. Identifications were performed with either a bolus protocol (n = 4) or an infusion protocol (n = 4), and the predicted [14C]inulin dynamics in the splanchnic and muscle interstitial fluid compartments were compared with measured values in thoracic duct lymph. Neither compartment predicted the thoracic duct [14C]inulin dynamics; however, a model based on a percentage contribution from each tissue bed fit the thoracic data well. The relative contribution of splanchnic interstitial fluid to the total thoracic duct lymph flow averaged 78 ± 5% for the bolus protocol and 54 ± 5% for the infusion protocol. Thus, we conclude that in the conscious animal, ∼25–50% of thoracic duct lymph originates from muscle interstitial fluid.
In vivo Glucose Metabolism in Obese and Type II Diabetic Subjects With or Without Hypertension
Authors: Bonora Enzo , Bonadonna Riccardo C , Del Prato Stefano , Gulli Giovanni , Solini Anna , Matsuda Masafumi , DeFronzo Ralph A
Published: September 2013

This study examined whether the presence of hypertension, an insulin-resistant condition, exacerbates the defect in insulin action observed in obesity and type II diabetes mellitus. Glucose metabolism in the basal state and in response to insulin was quantitated by using the euglycemic insulin (20 mU · min−1 · m−2) clamp in combination with 3-[3H]glucose infusion and indirect calorimetry in 20 obese nondiabetic subjects (10 hypertensive and 10 normotensive), 26 type II diabetic subjects (13 hypertensive and 13 normotensive), and 11 normal nondiabetic subjects. The two groups of obese subjects and the two groups of diabetic subjects were matched for sex, age, race, body mass index, and fat distribution. Both in the basal state and during insulin infusion, glucose disposal rates (total, oxidative, and nonoxidative) were similar in obese subjects with or without hypertension. Compared with control subjects, both groups of obese subjects were markedly insulin resistant. Similarly, type II diabetic individuals, whether normotensive or hypertensive, were equally insulin resistant. The severity of insulin resistance was nearly identical in obese and diabetic groups. In diabetic subjects, the inhibitory effect of insulin on hepatic glucose output, lipolysis, and lipid oxidation was blunted compared with normal subjects. In obese subjects the ability of insulin to inhibit lipolysis and lipid oxidation was impaired. However, hypertension did not alter the suppressive effects of insulin on hepatic glucose production, plasma free fatty acid levels, or lipid oxidation in either obese or type II diabetic subjects. These results indicate that hypertension does not confer a greater severity of insulin resistance than that already is present in obesity and type II diabetes mellitus.
Abnormal Activity in Diabetic Rat Saphenous Nerve
Authors: Russell Lisa C , Burchiel Kim J
Published: September 2013

This study was conducted to test whether abnormal spontaneous activity similar to that found after peripheral nerve trauma develops in diabetic nerve, and whether duration and/or severity of hyperglycemia affected ongoing activity. We maintained 32 diabetic BB Wistar rats on a euglycemic or hyperglycemic control regimen for 3–15 mo; 22 nondiabetic BB rats served as controls. All animals underwent acute saphenous nerve recordings. Whole nerve conduction velocities in 3- to 6-mo-old euglycemic diabetic rats were not different from controls, but 3- to 6-mo-old hyperglycemic diabetic conduction velocities were slower than in controls (P < 0.001) or euglycemic diabetic rats (P < 0.05). Compared with controls, 9- to 12-mo-old diabetic nerve conduction velocities were slower under both euglycemic (P < 0.029) and hyperglycemic (P < 0.04) regimens, but treatment groups did not differ. Combined 3- to 6-mo-old diabetic rats exhibited less resting sympathetic activity than controls under both euglycemic (P < 0.022) and hyperglycemic (P < 0.001) regimens. Sympathetic activity in 9- to 12-mo-old diabetic rats did not differ from controls. However, less sympathetic activity was found in older controls than in younger ones (P < 0.028). In conclusion: 1) saphenous nerve conduction velocity was slower in diabetic BB rats than in controls; 2) good glycemic control maintained normal conduction velocity in young adults, but the effect diminished with age; 3) resting sympathetic activity levels in young adult BB rats were lower than controls; and 4) sympathetic activity in old BB rats was diminished whether diabetes was present or not.