bluuebunny/crossref_metadata_2025 huggingface dataset:
Deficiency of Ascorbic Acid in Experimental Diabetes: Relationship With Collagen and Polyol Pathway Abnormalities
Authors: McLennan Susan , Yue Dennis K , Fisher Elizabeth , Capogreco Carmela , Heffernan Scott , Ross Glynis R , Turtle John R
Published: September 2013

The plasma and tissue concentration of ascorbic acid (AA) is reduced in diabetes. This study was designed to investigate the mechanism and significance of this phenomenon. The low plasma AA concentration of diabetic rats can be normalized by dietary AA supplement (20–40 mg/day), a dosage approximately equal to the maximal synthetic rate of this substance in the rats. Treatment of diabetic rats with this regime prevented the decrease in activity of granulation tissue prolyl hydroxylase (PRLase), an AA-dependent enzyme required for maintaining the normal properties of collagen. The decreased plasma AA concentration and granulation tissue PRLase activity in diabetes can also be normalized by the aldose reductase inhibitor tolrestat. We conclude that in diabetic animals there is a true deficiency of AA that may be responsible for some of the changes of collagen observed in diabetes. Treatment with AA or an aldose reductase inhibitor may prevent some of the diabetic complications with underlying collagen abnormalities.
Factors in Development of Diabetic Neuropathy: Baseline Analysis of Neuropathy in Feasibility Phase of Diabetes Control and Complications Trial (DCCT)
Authors:   The DCCT Research Group
Published: September 2013

The Diabetes Control and Complications Trial (DCCT) is a multicenter randomized clinical trial studying the effect of intensive insulin therapy on the early vascular and neurological complications of insulin-dependent diabetes mellitus (IDDM). During the feasibility phase of the DCCT, baseline neurological histories, physical examinations, and laboratory measurements of somatic and autonomic nerve function were obtained in 278 well-characterized IDDM subjects. Subjects were free of advanced complications, including the presence of peripheral or autonomic neuropathy sufficiently severe to require treatment. Analyses of the cross-sectional data reveal that clinically detectable peripheral neuropathy was present in 39% of the subjects. The presence of clinical neuropathy correlated with greater age, longer duration of IDDM, and male gender. The somatic and autonomic test results confirm the relationship between age, diabetes duration, and male gender and diabetic neuropathy. These results support an effect of age and gender on the development of diabetic complications.
Glycosylation of Low-Density Lipoprotein Enhances Cholesteryl Ester Synthesis in Human Monocyte-Derived Macrophages
Authors: Lopes-Virella Maria F , Klein Richard L , Lyons Timothy J , Stevenson Henry C , Witztum Joseph L
Published: September 2013

Glucose can react with the lysine residues of low-density lipoproteins (LDLs) and convert the lipoprotein to a form with a receptor-mediated uptake by cultured cells that is impaired. However, in contrast to other modified lipoproteins taken up by both murine and human macrophages via the scavenger-receptor pathway that may induce the formation of foam cells, glycosylated LDL is not recognized by murine macrophages, and thus far, it has not been shown to lead to marked intracellular accumulation of cholesterol in human macrophages. This study illustrates that glycosylated LDL incubated with human monocyte-derived macrophages, at a concentration of 100 micrograms LDL/ml medium, stimulates significantly more cholesteryl ester (CE) synthesis than does control LDL (10.65 ± 1.5 vs. 4.8 ± 0.13 nmol.· mg−1 cell protein · 20 h−1; P < .05). At LDL concentrations similar to those of plasma, the rate of CE synthesis in macrophages incubated with glycosylated LDL is more markedly enhanced than that observed in cells incubated with control LDL (3-fold increase). The marked stimulation of CE synthesis in human macrophages exposed to glycosylated LDL is paralleled by a significant increase in CE accumulation in these cells (P < .001). The increase in CE synthesis and accumulation seem to be mediated by an increase in the degradation of glycosylated LDL by human macrophages. Glycosylated LDL enters the macrophages and is degraded by the classic LDL-receptor pathway in slightly smaller amounts than control LDL, but its degradation by pathways other than the classic LDL receptor or scavenger receptor is markedly enhanced. These studies have shown a possible mechanism by which glycosylation of LDL may lead to the formation of foam cells and contribute to the acceleration of atherosclerosis in diabetes mellitus.
Composition Changes in Hepatic Microsomal Cytochrome P-450 During Onset of Streptozocin-Induced Diabetes and During Insulin Treatment
Authors: Favreau Leonard V , Schenkman John B
Published: September 2013

Monospecific polyclonal antibodies to five constitutive hepatic microsomal cytochromes P-450 were prepared. These antibodies were used to monitor alterations in the content of the enzymes in livers of diabetic male rats. Within 3 wk of onset of streptozocin-induced diabetes, immunodetectable levels of RLM3 and RLM5 were decreased by 85 and >95%, respectively. Insulin treatment for 1 wk reversed the decline in these isozymes and restored RLM3 to 60% and RLM5 to 53% of levels found in the untreated rat. After a 2nd wk of therapy, these levels were returned to 86 and 92%, respectively. In contrast, the levels of RLM5b and RLM6 were elevated in diabetes 1.7- and 8-fold, respectively. Insulin treatment for 1 wk only slightly decreased the levels of RLM5b but completely reduced RLM6 levels to those seen in age-matched untreated rats. After the 2nd wk of insulin treatment, the level of RLM5b was almost completely restored to normal, with no additional change in the RLM6 level. The level of a fifth enzyme, RLM5a, was not markedly altered by diabetes or by insulin treatment. The results suggest there are at least three types of responses by constituents of the cytochrome P-450 population to diabetes: no change in the microsomal content, a rapid increase when insulin level declines and restoration when insulin is supplied, and a rapid decline when insulin level declines and a restoration by insulin treatment.
Transcutaneous Oxygen Tension in Legs and Feet of Diabetic Patients
Authors: Gaylarde Peter M , Fonseca Vivian A , Llewellyn Gareth , Sarkany Imrich , Thomas P K , Dandona Paresh
Published: September 2013

Transcutaneous oxygen tension (tcPO2) of the legs and feet was measured at 37 and 44°C in 21 patients with diabetes mellitus, 9 of whom had peripheral neuropathy. At 37°C, tcPO2 in the legs and feet of diabetic patients with peripheral neuropathy was significantly higher (P < .02) than in control subjects and diabetic patients without neuropathy. Whereas tcPO2 in the legs of control subjects and nonneuropathic diabetic patients was > in the feet (P < .02), this leg-to-foot difference was absent in diabetic patients with neuropathy. After an increase in skin temperature to 44°C, tcPO2 increased in the legs and feet of all three groups, but the increase was smallest in diabetic patients with neuropathy and greatest in control subjects. In neuropathic (P < .02) and nonneuropathic (P < .02) diabetic patients, tcPO2 was significantly lower than in control subjects. These data are consistent with a loss of vasoconstrictor tone in the blood vessels perfusing skin and subcutaneous tissue at 37°C and an inability of these vessels to vasodilate and increase blood flow at 44°C in diabetic patients in general and neuropathic diabetic patients in particular. This inability to increase tcPO2 after an increase in temperature and possibly other vasodilatory stimuli may contribute to the pathogenesis of nonhealing ulcers, protracted infections, and gangrene, which characterize the diabetic foot.
Reduced In Vivo Biological Activity of In Vitro Glycosylated Insulin
Authors: Lapolla Annunziata , Tessari Paolo , Poli Tiziana , Valerio Anna , Duner Elena , Iori Elisabetta , Fedele Domenico , Crepaldi Gaetano
Published: September 2013

We evaluated the in vivo biological activity of in vitro extensively glycosylated insulin (GI) with the euglycemic-hyperinsulinemic glucose-clamp technique in postabsorptive nondiabetic subjects. Insulin-mediated glucose disposal was ∼30% lower (P < .03) with GI (9.2 ± 1.2 mg · kg−1 · min−1, mean ± SE) than with the nonglycosylated hormone (12.6 ± 0.7 mg · kg−1 · min−1) at comparable plasma insulin concentrations (∼90 μU/ml). Binding of GI to a specific receptor on circulating cells (erythrocytes and monocytes) was normal. We conclude that in vitro extensive glycosylation of insulin reduces its biological activity in vivo, as reflected by insulin-mediated glucose disposal, probably at a postreceptor level.
High Prevalence of Diabetes in Young Adult Ethiopian Immigrants to Israel
Authors: Cohen Margo P , Stern Ervin , Rusecki Yael , Zeidler Adina
Published: September 2013

We performed oral glucose tolerance tests in 158 Ethiopian immigrants to Israel. The subjects were <30 yr of age, had lived in Israel ≤4 yr, and originated from villages in the Gondar and Ambovar regions of Ethiopia. Most had been subjected to famine conditions in Ethiopia and/or extreme hardship in Sudan before or during immigration. All were lean. They revealed a profound change in dietary habits since their arrival in Israel, with consumption of large amounts of refined carbohydrate in place of spicy stews and injura (Ethiopian pita) that had constituted dietary staples in better times in Ethiopia. According to National Diabetes Data Group criteria, 14 (8.9%) of the subjects had diabetes, and another 14 (8.9%) had impaired glucose tolerance. In addition, 13 subjects had a dramatic increase in capillary blood glucose levels (>300 mg/dl) 1 h after ingestion of 75 g glucose, despite fasting and 2-h values well within the normal range, and they complained of associated symptoms during the 1st h of testing. Eleven of 137 men and 3 of 21 women had diabetes; 7 (5.1%) of the men and 7 (33%) of the women had impaired glucose tolerance. These results indicate a high prevalence of diabetes among young adult Ethiopian immigrants of relatively short residency in Israel, for which the factors responsible warrant further investigation.
Prevention of Recurrent Autoimmune Diabetes in BB Rats by Anti-Asialo-GM1 Antibody
Authors: Jacobson Jill D , Markmann James F , Brayman Kenneth L , Barker Clyde F , Naji Ali
Published: September 2013

BB rats exhibit a syndrome of spontaneous diabetes that has clinical and pathological characteristics analogous to those found in human insulin-dependent diabetes mellitus (IDDM). Islet tissue transplanted into spontaneously diabetic BB rats is uniformly destroyed by a recurrence of the autoimmune response that destroyed the diabetic subject's native islets. To examine recurrent autoimmune destruction of transplanted islets, it is necessary to exclude islet damage that might result from allograft rejection. We utilized neonatal tolerance induction to prevent rejection of Wistar-Furth (WF) (RT1u) islet allografts by spontaneously diabetic BB recipients. We determined that islet-recipient treatment with anti-asialo-GM1 (anti-AGM1) antibody prevents recurrent autoimmune diabetes that would otherwise destroy transplanted WF islet grafts. Anti-AGM1 therapy significantly decreased peripheral blood natural killer (NK) cell activity. These data suggest a role for NK cells in the pathogenesis of recurrent diabetes in neonatally tolerant BB rats.
Cardiac Hyperfunction in Insulin-Dependent Diabetic Patients Developing Microvascular Complications
Authors: Thuesen Leif , Christiansen Jens S , Mogensen Carl E , Henningsen Per
Published: September 2013

Cardiac function was studied by echocardiography in 80 insulin-dependent diabetic patients with no signs of ischemie heart disease and in 40 healthy control subjects. Echocardiographic findings were related to the urinary albumin excretion rate (UAE). In the diabetes group, fractional shortening of the left ventricle (FS) was 37.3% versus 34.3% (P < .01) in the control group, whereas indices of preload and afterload were at the same levels as in control subjects. In diabetic patients with preclinical nephropathy (UAE 20–200 μm/min), FS was 41.1% compared to 37.0% (P < .002) in patients with no signs of nephropathy (UAE <20 μ/min) and 34.8% (P < .001) in patients with clinical nephropathy (UAE <200 μg/min). Furthermore, in patients with preclinical nephropathy, afterload was significantly decreased, whereas preload was at the same level as in the other two groups of UAE. In conclusion, a condition of cardiac hyperfunction has been found in diabetic patients with no signs of ischemie heart disease and seems pronounced in diabetic patients developing microvascular disease (patients with preclinical nephropathy), probably secondarily to a condition of hyperperfusion in these patients.
Effect of Intensive Insulin Therapy on Glycemic Thresholds for Counterregulatory Hormone Release
Authors: Amiel Stephanie A , Sherwin Robert S , Simonson Donald C , Tamborlane William V
Published: September 2013

To evaluate the effect of strict glycemie control of insulin-dependent diabetes mellitus (IDDM) on the plasma glucose threshold initiating counterregulatory hormone responses to hypoglycemia, we used the glucose clamp technique to produce a standardized gradual glucose decline from 90 to 40 mg/dl in seven young IDDM patients before and after 2–6 mo of intensified insulin therapy. Before intensive therapy [hemoglobin A1 (HbA1) 9.6 ± 1.1%], epinephrine responses were triggered at a higher plasma glucose level (67 ± 4 mg/dl) than in normal control subjects (56 ± 1 mg/dl, P < .05), and clinical symptoms of hypoglycemia appeared at glucose levels of 50–60 mg/dl. After intensive therapy (HbA, 7.1 ± 0.7%), the glucose threshold for epinephrine release consistently declined to values (46 ± 2 mg/dl) below normal (P < .01). Furthermore, epinephrine concentrations were markedly reduced at each hypoglycemie level, and a greater hypoglycemie stimulus was required to elicit symptoms. The glucose threshold stimulating release of growth hormone also significantly declined after intensive therapy. We conclude that strict glycemie control of IDDM lowers the plasma glucose level required to generate epinephrine release during hypoglycemia. This may diminish patient recognition of moderate hypoglycemia and increase the risk of severe hypoglycemia in intensively treated IDDM.
Association of HLA-DQw3 (TA10−) With Type I Diabetes Occurs With DR3/4 but not DR1/4 Patients
Authors: Tait Brian D , Mraz Grant , Harrison Leonard C
Published: September 2013

We have shown in previous studies that the TA10− subtype of HLA-DQw3 is significantly increased in HLA-DR4 type I (insulin-dependent) diabetic patients. Data presented in this article indicate that this association only occurs in heterozygous DR3/4 patients and not in DR1/4 patients. Because there is an interactive effect of both DR3/4 and DR1/4 in type I diabetes, the data indicate that the contribution of DR4 haplotypes varies depending on the haplotype borne on the homologous chromosome. In addition, the frequency of the B44-DR4 haplotype was shown to be decreased in DQw3 (TA10−) diabetic subjects who were DR3/4 compared with those who were DR1/4 or DR4/X (a pooled group of patients with different DR alleles). This finding suggests that the decrease in the B44-DR4 haplotype in type I diabetes is not solely dependent on its linkage disequilibrium with the DQw3 (TA10−) allele but suggests there is an additional effect exerted independently.
Effect of Chronic Diabetes on Myocardial Fuel Metabolism and Insulin Sensitivity
Authors: Barrett Eugene J , Schwartz Ronald G , Young Lawrence H , Jacob Ralph , Zaret Barry L
Published: September 2013

To assess the effect of chronic insulin-deficient diabetes on myocardial fuel substrate metabolism in vivo, we measured the myocardial balance of glucose, free fatty acids (FFAs), and amino acids in nine postabsorptive conscious dogs 4–6 wk after treatment with streptozocin. The acute effect of insulin on the myocardial balance of these same substrates was measured in six dogs by use of the euglycemic insulin clamp technique. To further examine the effect of insulin on heart amino acid balance, we studied three additional dogs given a constant infusion of amino acids during the insulin clamp to blunt the insulin-induced hypoaminoacidemia. In these dogs, the fasting plasma glucose concentration was markedly elevated (258 ± 3 mg/dl). In the basal period, there was no significant glucose uptake by the heart [arterial vs. coronary sinus concentration difference (Δ) = 1.0 ± 2.0 mg/dl]; furthermore, physiologic hyperinsulinemia did not stimulate glucose uptake (Δ = 2.0 ± 2.5 mg/dl). Postabsorptively, arterial FFAs were elevated (1550 ± 320 μμ) in diabetic animals, and there was a significant net extraction of FFAs by the heart (net uptake 26 ± 9 μmol/min; extraction ratio 30 ± 8%). During the insulin clamp, arterial FFAs declined (645 ± 240 μM), as did heart FFA uptake (11 ± 6 μmol/min), and the net extraction ratio for FFAs was unchanged (30 ± 7%). Similarly, the arterial branched-chain amino acid (BCAA) concentration was elevated in the postabsorptive state, and there was a significant myocardial uptake of these amino acids and of alanine. With infusion of insulin alone or a combination of insulin and amino acids, there was a highly significant linear correlation between the arterial BCAA concentration and myocardial BCAA uptake (r = .80, P < .02). Glutamine is the dominant amino acid released by the diabetic myocardium, both in the basal period and during insulin infusion (0.4 ± 0.4 and 1.1 ± 0.4 μmol/min, respectively). We conclude that when compared with myocardium of normal dogs, the myocardium of diabetic dogs is severely resistant to the action of insulin to promote glucose uptake.
Diabetes and Diuretic-Induced Alterations in Function of Rat Urinary Bladder
Authors: Kudlacz Elizabeth M , Chun Alexa L , Skau Kenneth A , Gerald Michael C , Wallace Lane J
Published: September 2013

Studies were done to characterize the bladder dysfunction associated with diabetes mellitus and to distinguish between changes occurring from increased diuresis and autonomie neuropathy. Four experimental conditions were compared: control, 4-wk-s t re ptozoc in-induced diabetes, sucrose feeding (diuretic), and galactose feeding (diuretic and sugar alcohol). A 10-fold increase in urine output and 25–50% increases in bladder weight, protein content, and DNA content were observed in all noncontrol treatment groups. Compliance properties were studied by measuring the intravesicular pressure as the bladder was infused with buffer in vitro. All treated bladders exhibited a reduction in plateau pressure and an increase in fluid capacity. Thus, diuresis results in an increased bladder size, which correlates with an alteration of compliance properties. Nervous system control in anesthetized rats was examined by monitoring contractions as the bladder was infused with buffer. Three distinct patterns of response were observed: normal, diabetic, and diuretic (galactose and sucrose treatments). The difference between responses in diuretic and diabetic animals suggests the presence of a diabetes-induced alteration in nerve regulation of the bladder. Reserpine pretreatment of control or diuretic models produced marked changes in the pattern of contractions, whereas pretreatment of diabetic rats had only modest effects. This suggests that diabetic bladders were lacking sympathetic control before the drug treatment. When rats treated for 4 wk with galactose were removed from this diet for 4 wk before testing, the bladders responded similarly to controls. This observation, coupled with the fact that galactose did not produce the same response as diabetes in the in vivo experiments, suggests that the galactose model does not produce irreversible functional neuropathies.
Diabetes-Related Changes in L-Tryptophan–Induced Release of Striatal Biogenic Amines
Authors: Broderick Patricia A , Jacoby Jacob H
Published: September 2013

In vivo voltammetry was used to measure the synaptic release of rat striatal dopamine and serotonin after the administration of the amino acid L-tryptophan to streptozocin-induced diabetic rats. Dopamine and serotonin release from rat striatum was studied at a short-term or acute (3-day) interval and a long-term or chronic (3- to 7-wk) interval after the induction of diabetes. The study was also done in age-, sex-, and food-matched controls. The findings show that L-tryptophan decreased dopamine release from rat striatum in nondiabetic rats. The decreased striatal dopamine release, after L-tryptophan administration, was exacerbated in acutely diabetic rats and further exacerbated in chronically diabetic rats. By contrast, rat striatal serotonin release predictably increased after L-tryptophan injection in nondiabetic rats. A further increased striatal serotonin release was seen in acutely diabetic rats. Chronically diabetic rats, however, responded to L-tryptophan with a dramatic and significant decrease in striatal serotonin release. The results show that in acutely diabetic and normal rats, L-tryptophan administration reduced striatal dopamine and increased striatal serotonin release, whereas in chronically diabetic rats, the release of both biogenic amines was decreased. The findings indicate that the progression of diabetes is associated with an impaired ability to release primary neurotransmitter biogenic amines.
Abnormal Thermoregulation in Diabetic Autonomic Neuropathy
Authors: Scott Adrian R , MacDonald Ian A , Bennett Terence , Tattersall Robert B
Published: September 2013

Hypothermia has been reported to be more common in diabetic people than in nondiabetic people, and we have investigated the possibility that autonomie neuropathy may be associated with disordered thermoregulation. After an overnight fast and maintenance of normoglycemia, 12 insulin-treated diabetic patients with and 11 without neuropathy and 12 nondiabetic control subjects, all <55 yr, were subjected to external cooling by perfusing water at 16°C through a liquid-conditioned coverall for ≤45 min. Patients with autonomie neuropathy had impaired vasoconstriction to cooling, particularly in the foot, calf, and forearm. Core temperature rose by 0.2°C in control subjects and by 0.15°C in patients with diabetes but no neuropathy. In contrast, group mean core temperature was unchanged in those with autonomie neuropathy and fell in 3 subjects (P < .001). Cooling caused shivering in 6 patients with diabetic autonomie neuropathy, but not in those with neuropathy or control subjects (P < .05). Baseline metabolic rates were similar in all three groups, but the increase after cooling was significantly greater among those who shivered (P < .05–.02). Thus, young diabetic patients with autonomie neuropathy have impaired thermoregulation to a relatively short period of external cooling, even during metabolic stability, which may predispose to hypothermia.
Diabetes Affects Sorbitol and myo-Inositol Levels of Neuroectodermal Tissue During Embryogenesis in Rat
Authors: Sussman Ilene , Matschinsky Franz M
Published: September 2013

ATP, ADP, phosphocreatine (PCr), creatine (Cr), glucose, malate, sorbitol, and myo-inositol (Ml) were measured by quantitative histochemical techniques in pure neuroectodermal tissue of rat embryos of gestation days 11 and 12 that were dissected from normal and streptozocin-induced diabetic mothers. Neither gestational age nor maternal diabetes affected the tissue's energy potential (ATP-to-ADP and PCr-to-Cr ratios). Diabetes resulted in a fourfold rise in the embryonic glucose and a 25% increase in neuroectodermal malate content. Maternal hyperglycémie caused a rise in fetal sorbitol at days 11 and 12 of gestation. The Ml content of the neuroectoderm was not affected by the maternal diabetic state in prefusion embryos (day 11); however, the near doubling of Ml that occurs from day 11 to day 12 during normal development was prevented. Thus, embryos isolated from diabetic mothers on gestation day 12 had 30% less Ml than embryos isolated from normal mothers. From these data we conclude that a rise in tissue sorbitol is not always accompanied by a fall in tissue Ml. These results and recent information in the literature implicate involvement of decreased Ml concentrations in the process leading to malformation of the nervous system in diabetic embryopathy.
Glyceraldehyde Phosphate and Methyl Esters of Succinic Acid: Two “New” Potent Insulin Secretagogues
Authors: MacDonald Michael J , Fahien Leonard A
Published: September 2013

We discovered that two physiologically occurring metabolic intermediates, glyceraldehyde phosphate and succinate, are potent insulin secretagogues. No other glycolytic intermediate besides glyceraldehyde phosphate was insulinotropic. Succinate, when added to islets as either its monomethyl or dimethyl ester to increase its cellular permeability, was also insulinotropic. In islets, as in other cell types, these esters are apparently hydrolyzed intracellulary to succinate. Unesterified succinate and other unesterified citric acid–cycle intermediates did not stimulate insulin release. Initiation of insulin release by esters of succinate suggests that mitochondrial metabolism alone is sufficient to initiate and support insulin release. However, this is specific for succinate in that esters of fumarate, pyruvate, and citrate were not insulinotropic.
Effects of Insulin on Vasoconstrictive Responses to Norepinephrine and Angiotensin II in Rabbit Femoral Artery and Vein
Authors: Yagi Shinji , Takata Shigeo , Kiyokawa Hiroaki , Yamamoto Masakazu , Noto Yutaka , Ikeda Takayuki , Hattori Nobu
Published: September 2013

To determine whether insulin has a vasodilator action on the artery and vein, the effects of insulin at varying concentrations (120 μU/ml, 1.2 mU/ml, 12 mU/ml, and 120 mU/ml) on vasoconstriction by norepinephrine (NE) and angiotensin II (ANG II) were studied in the isolated rabbit femoral artery and vein. Helical strips were suspended in an organ bath filled with modified Krebs solution (pH 7.4), were gassed with 95% O2/5% CO2 at 36°C, and isotonic contractions were measured. Insulin significantly and dose dependently inhibited the vasoconstriction induced by NE (10−8 M for the artery and 10−7 M for the vein) at ≥1.2 mU/ml for both the artery and vein and the vasoconstriction induced by ANG II (3 × 10−10 M for the artery and 3 × 10−9 M for the vein) at ≥1.2 mU/ml for the artery and ≥12 mU/ml for the vein. The results indicate that insulin has an inhibitory effect on NE- and ANG II–induced contraction in both the artery and vein, and this appeared to be a contributory factor in the hypotensive effect observed in diabetic patients treated with insulin.
Identification of Nucleotide Substitution in Gene Encoding [LeuA3]Insulin in Third Japanese Family
Authors: Awata Takuya , Iwamoto Yasuhiko , Matsuda Ayako , Kuzuya Takeshi
Published: September 2013

We previously described a new case of abnormal insulinemia in Japan. In one allele, nucleotide-sequence analysis revealed a substitution in the codon for the third position of insulin A chain (GTG→TTG), causing [LeuA3]insulin. This point mutation is the same as that found in insulin Wakayama. In this family, the mutant insulin allele cosegregated with an 850-base pair PvuII allele of the hypervariable region 5′-flanking the insulin gene.
Alteration of 1,2-Diacylglycerol Content in Myocardium From Diabetic Rats
Authors: Okumura Kenji , Akiyama Naohiko , Hashimoto Hidekazu , Ogawa Kouichi , Satake Tatsuo
Published: September 2013

1,2-Diacylglycerol has been proposed to be a secondary messenger; therefore, in this study we evaluated the amount of 1,2-diacylglycerol in heart tissue from streptozocin-induced diabetic rats and examined the effect of insulin treatment on 1,2-diacylglycerol content. Diabetic rats had lower body and ventricular weights and higher ratios of ventricular to body weight, all of which shifted toward normal values after 4 wk of untreated diabetes followed by 4 wk of insulin treatment. The contents of major phospholipids were significantly depressed in the diabetic rat hearts. In contrast, the triglyceride and cholesterol contents in the myocardium were increased by streptozocin injection and completely normalized by insulin treatment, and glucose levels returned to normal. The 1,2-diacylglycerol content in the myocardium was also significantly elevated in the diabetic rats compared with age-matched controls. Moreover, the 1,2-diacylglycerol content was significantly higher in rats with 4 wk of diabetes than in those with 8 wk of diabetes. Insulin treatment in the diabetic rats, however, did not produce any decrease in 1,2-diacylglycerol content. The results of this study suggest that the development of cardiomyopathy induced by streptozocin injection is associated with a high 1,2-diacylglycerol level, which may result in the activation of protein kinase C. Insulin is one of the agonists that generates 1,2-diacylglycerol in myocytes; however, the relationship between the sustained 1,2-diacylglycerol level and the normalization of diabetes by insulin administration is unclear.
Reevaluation of Urine C-Peptide as Measure of Insulin Secretion
Authors: Tillil Hartmut , Shapiro E Timothy , Given Bruce D , Rue Paul , Rubenstein Arthur H , Galloway John A , Polonsky Kenneth S
Published: September 2013

Urine C-peptide (UCP) has been proposed as a measure of insulin secretion, because insulin and C-peptide are cosecreted in equimolar concentrations by the pancreatic β-cell. The validity of this approach was tested by comparing insulin secretion rates, calculated by application of a two-compartmental analysis of peripheral C-peptide concentrations, with UCP excretion rates. Insulin secretion and UCP excretion with subjects on a mixed diet were simultaneously measured over a 24-h period in 13 patients with non-insulin-dependent diabetes mellitus and in 14 matched nondiabetic control subjects. The fraction of secreted C-peptide that was excreted in the urine (fractional C-peptide excretion) showed considerable intersubject variability in the diabetic (11.3 ± 1.6%, range 3.9–20.8) and control (8.0 ± 1.7%, range 1.1–27.9, P = .07) subjects (means ± SE). UCP clearance demonstrated a similar degree of variability and was not significantly different (P = .07) between diabetic (23.8 ± 3.0 ml/min) and control (16.5 ± 2.7 ml/min) subjects. In control subjects, the 24-h insulin secretion rate correlated more closely with the fasting insulin secretion rate (r = .97, P = .0001), fasting C-peptide (r = .81, P = .0005), and fasting insulin (r = .80, P = .0005) concentrations than with the 24-h UCP excretion rate (r = .62, P = .02). Similar results were obtained in the diabetic patients. The mean coefficient of variation of fractional UCP excretion in 7 nondiabetic control subjects who were studied on a mixed diet over a 24-h period on two occasions was 28.4 ± 10.5%, that of UCP clearance was 28.9 ± 8.6%, and that of simultaneously measured creatinine clearance was 7.8 ± 3.5%. In summary, the fraction of secreted C-peptide that appears in the urine varies considerably between subjects and in the same subject studied repeatedly. UCP excretion does not correlate as well with 24-h insulin secretion as does the fasting insulin secretion rate or the fasting C-peptide or fasting insulin concentration. We conclude that, because the fraction of secreted C-peptide that is excreted in the urine varies considerably between subjects and in the same subject studied on different occasions, UCP is of only limited value as a quantitative measure of endogenous insulin secretion.
Distinct Macrophage Subpopulations in Pancreas of Prediabetic BB/E Rats: Possible Role for Macrophages in Pathogenesis of IDDM
Authors: Walker Robert , Bone Adrian J , Cooke Anne , Baird Joyce D
Published: September 2013

Use of monoclonal antibodies directed against rat macrophages and serial pancreatic biopsy in the prediabetic period have enabled us to document the involvement of macrophages in the pancreatic events leading to onset of diabetes in the spontaneously diabetic BB/E rat. A few weeks before onset of disease, there is marked recruitment and accumulation of ED1+ macrophages at periductal and perivascular locations adjacent to noninfiltrated islets. These recruited cells, distinct from the resident ED2+ tissue macrophages, then infiltrate the islets. Infiltration of the pancreas by ED1 + macrophages is therefore a very early event in the prediabetic period and suggests a possible role for macrophages in the pathogenesis of insulin-dependent diabetes mellitus (IDDM) in this animal model.
Insulin-Gene Expression in Extrafetal Membranes of Rats
Authors: Rau Kimberley , Muglia Louis , Locker Joseph
Published: September 2013

We quantified fetal rat extrapancreatic insulin-gene expression by measuring mRNA in the yolk sac and placenta. Yolk sac makes a significant contribution to the total fetal insulin stores. The placenta contains a much smaller amount of insulin mRNA. Yolk sac insulin mRNA is barely detectable at 16 days gestation but increases markedly to a maximum at 21 days, 1 day before birth. In contrast to the pancreatic 550-nucleotlde (n) insulin mRNA, yolk sac has a 720-n mRNA. However, on removal of the terminal poly(A), both transcripts produce a 440-n RNA, the size predicted for a fully processed insulin mRNA.
Influence of Serum Amylase and Plasma Glucose Levels in Pancreas Cadaver Donors on Graft Function in Recipients
Authors: Hesse Uwe J , Sutherland David ER
Published: September 2013

In a series of 101 pancreas transplants from brain cadaver donors, serum amylase levels were determined preoperatively in 47 donors, and plasma glucose levels were monitored in 94 donors. Eighty-six percent of the donors died from head injury and 14% from asphyxia. No donors had a history of diabetes or pancreatitis, and the pancreas was grossly normal in all donors. Of the 47 cadaver pancreas donors in whom serum amylase levels were measured, the values of 20 donors were elevated (110–994 IU/L), and the values of 11 donors were >300 IU/L. In 51 of 94 braindead cadaver pancreas donors in whom plasma glucose determinations were made, hyperglycemia was present (200–980 mg/dl). Early posttransplant pancreas-graft function was excellent in all recipients except for 5 patients in whom the grafts had to be removed for reasons not related to donor serum amylase and plasma glucose levels. Hyperamylasemia and hyperglycemia are probably not contraindications for cadaver pancreas organ donation unless overt pancreatic trauma, pancreatitis, or a history of diabetes is present.
Quantitative Analysis of Microvasculature of Rat Pancreas Transplants in Acute Rejection
Authors: Nakai Ichiro , Aikawa Ichiro , Oka Takahiro
Published: September 2013

The changes of the microvasculature of rat pancreas transplants during acute rejection were investigated and quantitatively analyzed. The vessels in pancreas transplants increased in caliber and decreased in density during acute rejection. These changes were marked in the exocrine pancreas, especially in central zones, whereas changes in islets were mild. These results indicate that the early deterioration of exocrine function is closely related to vascular destruction.
Insulin Release from Isolated Islets of Langerhans after Segmental-Pancreas Autotransplantation in Dogs
Authors: Duron Jean-Jacques , Imbaud Patrice , Roux Jean Marc , Dutet Didier , Dubois Michele , Ravel Denis , Duhault Jacques
Published: September 2013

Pancreas transplantation is warranted essentially by the quality of glucose regulation. Although the fasting blood glucose is invariably normal, this may not be the case during glucose load tests. The purpose of this study was to examine dysregulation within the isolated islet originating from a segmental-pancreas autograft in the dog. Results show an increased basal insulin secretion by the graft islets in static incubation compared with that of islets originating from the head of the pancreas and left in situ. This abnormal secretion may be accounted for by various factors intervening within the graft or the isolated islet, thus suggesting a possible improvement in the surgical model.
Toxicity of FK-506 in Human Fetal Pancreas
Authors: Leonard Dann K , Landry Ann S , Sollinger Hans W , Hullett Debra A
Published: September 2013

The toxic effects of FK-506 (FK), a newly discovered immunosuppressive agent isolated from Streptomyces tsukubaensis, were studied in the human fetal pancreas (HFP) system. Human fetal pancreas expiants (14–21 wk gestation) were cultured up to 72 h with either 10−10 10−7 M FK or 10−8 to 10−5 M cyclosporin A (CsA), then examined histologically and functionally with a stimulated insulin-release assay. Additionally, FK and CsA were tested for the ability to suppress cellmediated immunity with a human mixed-lymphocyte reaction (MLR). Previous studies have demonstrated that near-complete immunosuppression is obtained with FK at 10−8 M and CsA at 10−6 M. When cultured up to 72 h throughout the concentration range, neither FK nor CsA altered HFP cellular architecture, and indirect immunoperoxidase staining for insulin demonstrated no change in quantity or distribution of insulin-producing β-cells compared with control tissue. Drug-cultured HFP also retained the ability to release insulin in response to a glucose/theophylline challenge. Finally, 50% inhibition of a human MLR was achieved with FK at 2 × 10−9 M and CsA at 2 × 10−7 M, demonstrating the 100-fold greater potency of FK. Our results suggest that further work with FK will show that this immunosuppressive agent can be used with HFP transplantation into diabetic patients without toxicity to HFP.
Prolonged Cryopreservation of Purified Human Pancreatic Islets
Authors: Kneteman Norman M , Alderson Derek , Scharp David W , Lacy Paul E
Published: September 2013

Long-term islet storage would facilitate many aspects of islet research and clinical islet transplantation. Collagenase-isolated, Ficoll-purified islets from eight cadaveric pancreases were stored in liquid nitrogen for 44 ± 9 days after dimethyl sulfoxide equilibration and slow cooling. Rapid rewarming and 48 h of culture preceded repeat evaluation of recovery by islet counts, insulin extraction, and glucose-stimulated perifusion. Islet recovery was 94 ± 4% by count and 90 ± 22% by insulin extraction immediately after thawing. After an additional 48 h in culture, recovery was 74 ± 12% by insulin extraction and 79% by quantitative perifusion culture. Perifusion demonstrated normal baseline and first-phase insulin secretion with decreased secondphase insulin secretion after cryopreservation. Insulinstained sections and electron microscopy revealed preserved islet morphology and ultrastructure. Granulated islets with preserved morphology were recovered 14 days after renal subcapsular xenografting into nude mice. This study demonstrates high recovery and good functional activity of human islets after prolonged cryopreservation.
Failure of Canine Islet Allotransplantation After Kidney Transplantation
Authors: Guy Andrew J , Griffin S Michael , Alderson Derek , Farndon John R
Published: September 2013

Eight dogs with previously established kidney allografts, immunosuppressed with cyclosporin A, received islet allografts from their respective original kidney donors. The median islet-graft functional survival was only 10.5 days, significantly less than for six similarly immunosuppressed dogs receiving only islet allografts (48.5 days, P < .05). Three of the eight dogs that received sequential kidney and islet allografts had experienced no kidney-graft rejection episodes before islet transplantation, but their islet grafts were all rejected within 19 days. In the pancreatectomized dog, prior donor-specific kidney transplantation has an adverse effect on subsequent islet-graft survival.
Results With Combined Kidney and Paratopic Segmental-Pancreas Transplantation
Authors: Brons I Gabrielle M , Calne Roy Y , Jamieson Neville V , Rolles Keith , Williams Paul F , Evans David B
Published: September 2013

Rehabilitation and quality of life after combined pancreas and kidney transplantation was assessed in 15 previously diabetic patients in renal failure and compared with 11 diabetic patients in renal failure transplanted with a kidney only. The paratopic segmental-pancreas-grafting technique, which allows physiologic insulin delivery into the portal venous system, was used in 13 patients; 2 patients received a heterotopic segmental-pancreas graft, resulting in systemic insulin delivery. A kidney was transplanted heterotopically in all cases. Mean age, duration of diabetes, retinopathy, neuropathy, mortality, infection rate, and immunosuppressive treatment did not differ significantly between the groups. Diabetic patients with only kidney transplants had difficulties adjusting to their diabetes, which may be partly due to the immunosuppressive treatment. The quality of life only marginally improved. In contrast, patients with a combined pancreas-kidney graft achieved full rehabilitation within a short time.
Normalization of Hyperglycemia in Diabetic Rats by Intraportal Transplantation of Cryopreserved Islets From Four Donors
Authors: Vasir Baldev S , Gray Derek WR , Morris Peter J
Published: September 2013

Techniques for freezing rat islets have been examined by the intensive use of the supravital stains fluorescein diacetate and ethidium bromide. By the use of a simple scoring system, the effect of the cooling rate, treatment with dimethyl sulfoxide (DMSO), rate of thawing, and postthaw culture were examined. These studies showed the most effective method to be a 24-h culture of islets, followed by partial incubation with 20% DMSO at 0°C, followed by seeding at −8°C in an alcohol bath. The islets were then cooled at a rate of −0.25°C/min to −40°C followed by quenching in liquid nitrogen at −196°C. Rapid thawing at 37°C was then followed by a 24-h culture. Islets from four Lewis rat donors were cryopreserved, counted, and transplanted intraportally into streptozocin-induced diabetic Lewis rats. Corresponding control transplants were performed with islets from four donors only cultured for 48 h. The results showed that reversal of hyperglycemia in severely diabetic rats was obtained at 5, 5, 6, 6, 6, or 8 days with cryopreserved islets from four donors, compared to reversal of diabetes at 1, 4, 5, 6, 7, and 12 days with islets from four donors subjected to culture alone. The new cryopreservation technique has several small modifications over previously described methods and results in a significant improvement in islet survival.
Angiogenesis and Hemodynamics of Microvasculature of Transplanted Islets of Langerhans
Authors: Menger Michael D , Jaeger Sabine , Walter Paul , Feifel Gernot , Hammersen Frithjof , Messmer Konrad
Published: September 2013

Transplantation of isolated islets of Langerhans is frequently followed by early loss of islet function. Because whether this is caused by insufficient vascularization or graft rejection is unknown, angiogenesis and microvascularization of islet grafts were studied in vivo by means of intravital microscopy. After transplantation of syngeneic islets in hamster dorsal skin-fold chambers, 97% (n = 66) of the islets exhibited the first signs of angiogenesis at days 2–4, characterized by sinusoidal sacculations and capillary sprouts. After 10 days, angiogenesis was completed, consisting of a microvascular network similar to those of islets in situ: arterial supply, afferent and efferent capillary loops, and venular drainage. Functional density of microvessels was 700.1 ± 127.0 cm−1, and erythrocyte velocity was 0.58 ± 0.35 mm/s. Intracellular insulin was demonstrated immunohistochemically. Electronmicroscopic studies revealed normal fine structure of the capillary wall. The model allows in vivo analysis of microvascular phenomena occurring in host-vs.-graft reaction after allogeneic and xenogeneic islet transplantation. Furthermore, it may be used to quantitatively assess immunosuppressive regimens.
Bovine Islets of Langerhans: Potential Source for Transplantation?
Authors: Hering Bernhard J , Romann Dietmar , Clarius Astrid , Brendel Mathias , Slijepcevic Milivoj , Bretzel Reinhard G , Federlin Konrad
Published: September 2013

Two methods are described for large-scale isolation of islets from the bovine pancreas. With the single-endpoint technique the average number of islets isolated from a 73.3-g pancreas sample was 150,560, representing an estimated total islet volume of 0.391 ml. Pancreases processed by the continuous digestion-filtration method yielded an average of 246,229 islets from a 93.9-g pancreas sample, representing an estimated total islet volume of 0.458 ml. Isolated bovine pancreatic islets demonstrated a well-preserved endocrine cell ultrastructure, responded to acute stimulation with propionic acid, and temporarily reversed experimental diabetes in mice.
OKT3 Rescue Therapy in Pancreas-Allograft Rejection
Authors: Stratta Robert J , Sollinger Hans W , D'Alessandro Anthony M , Pirsch John D , Kalayoglu Munci , Belzer Folkert O
Published: September 2013

OKT3 has emerged as a highly effective antirejection therapy, but its efficacy in pancreas transplantation remains to be determined. During a 26-mo period, 46 vascularized pancreas transplants were performed with pancreaticoduodenocystostomy. Twenty-one patients (45.7%) were treated with OKT3. Indications for OKT3 use included steroid- and/or antilymphoblast globulinresistant rejection in isolated-pancreas transplant (n = 8) or simultaneous pancreas-kidney-transplant (n = 13) recipients. A total of 46 rejection episodes occurred (mean 2.2). OKT3 was administered for a 14-day course concomitant with pulsed corticosteroide, azathioprine, and cyclosporin. OKT3 rescue therapy was successful in 13 cases (61.9%). The mean time to rejection reversal was 8.8 days (range 5–14 days). In isolated-pancreas transplants, OKT3 reversed only 1 episode of rejection (12.5%). In contrast, 12 episodes (92.3%) of allograft rejection were responsive to OKT3 in simultaneous pancreas-kidney recipients (P < .05). Graft loss from rejection occurred at a mean 5.5 mo posttransplantation. OKT3 therapy was more successful in the setting of early rejection, rejection in combined pancreas-kidney transplants, and rejection not associated with hyperglycemia. No graft loss due to infection or patient death has occurred after OKT3 therapy. After a mean follow-up of 17.3 mo, patient survival was 89.1%, and allograft survival was 26.3% in isolated-pancreas and 85.2% in simultaneous pancreas-kidney transplants (P < .05). Salvage therapy with OKT3 is a safe and effective means of reversing rejection in pancreas-allograft recipients. OKT3 is more effective in simultaneous pancreas-kidney recipients due to the earlier diagnosis of rejection.