bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiologic Effects of Epinephrine on Glucose Turnover and Plasma Free Fatty Acid Concentrations Mediated Independently of Glucagon
Authors: Gray D E , Lickley H L A , Vranic M
Published: September 2013

It has been suggested that the effects of epinephrine on glucose production by the liver may be mediated through glucagon. To investigate this possibility, epinephrine (EPI) (0.2 or 0.1 μg/kg-min) was infused in 12 conscious normal dogs with or without somatostatin (ST) (0.05 μg/kg-min), a known inhibitor of glucagon and insulin release. EPI (0.2 μg/kg-min) induced a sustained hyperglycemia. This resulted from both an increase in glucose production, which rose initially to 45% above basal and then plateaued at suprabasal levels, and a small but noticeable reduction (18%) in the metabolic clearance rate of glucose. Plasma levels of both immunoreactive glucagon (IRG) and insulin (IRI) also increased transiently. ST plus EPI resulted in a more severe hyperglycemia, which was due to an exaggerated initial peak of glucose production. This response occurred despite a clear suppression (71%) of IRG below basal. ST blunted the initial EPI-induced IRI peak, but IRI never fell below basal with the combined infusion of EPI and ST. The blunting of this initial insulin peak may have affected the hyperglycemie response to EPI. The lower dose of EPI (0.1 μg/kg-min) had a similar but less definite effect on glucose regulation and caused both insulin and glucagon levels to rise. However, at the lower EPI dose, ST had no appreciable effect on insulin release (as judged by peripheral IRI levels), although IRG was again greatly suppressed. Neither the EPI-induced hyperglycemia nor the rapid rise in glucose production was affected by ST, suggesting that the EPI-induced hyperglycemia is not mediated through glucagon release. It also appears that elevated EPI levels can compensate for the role of basal glucagon in regulation of basal glucose production in the postabsorptive state. EPI induced a transient 120% rise in free fatty acid (FFA) levels. The rise in FFA was more marked and more sustained when ST was given together with EPI irrespective of whether the initial EPI-induced insulin peak was blunted or remained unaltered, thus indicating a possible effect of ST on EPI-induced lipoly-sis. The same low dose of ST (0.5 μg/kg-min) infused without EPI greatly suppressed both IRG and IRI below basal (60%).

Thus (1) EPI infusion induced sustained hyperglycemia, resulting from a transient increase in glucose production and an inhibition of metabolic clearance of glucose; both IRG and IRI were also transiently increased. (2) The effect of EPI on glucose production was independent of glucagon, but it was possibly enhanced by suppression of the initial insulin peak. (3) A low dose of ST, which, by itself, suppressed basal IRI and IRG release, was able to override the effect of EPI on IRG but not on IRI release. Thus, the effect of a selective glucagon suppression could be studied. (4) EPI increased plasma FFA only transiently. (5) ST may directly or indirectly increase the lipolytic effect of EPI.
The Role of Hypoinsulinemia in Exercise Metabolism
Authors: Issekutz B
Published: September 2013

Dogs with indwelling catheters in the jugular vein and in the carotid artery ran on a treadmill (15% slope, 90 m/min). Hepatic glucose production (Ra), glucose utilization (Rd), and the metabolic clearance rate (MCR) of glucose were measured according to the primed constant rate infusion tracer techniques using 3-3H-glucose as tracer. In addition, plasma insulin (IRK) and glucagon (IRG) levels were determined. In 60 min, exercise increased Ra from 3.8 ± 0.3 to 8.5 ± 0.9 mg/kg min and MCR from 4.0 ± 0.2 to 10.4 ± 0.8 ml/kg min. Plasma insulin declined from 11.4 ± 1.2 to 7.9 ± 0.6 μ-U/ml and glucagon rose from 70 ± 10 to 110 ± 12 pg/ml. After 1 h, after a priming dose (0.36 g/kg), mannoheptulose was infused (6 mg/kg min) for 60 min. IRI fell to 3.4 μU/ml and IRG did not change significantly. Ra rose about 100% (to 16.3 ± 2.1 mg/kg min) and plasma glucose increased from 97 ± 2 to 200 ± 21 mg/dl followed by a slow rise of Rd. The MCR showed a transient decline from 10.3 ± 0.8 to 8.3 ± 1.5 ml/kg min. After that, it did not differ significantly from controls. These effects could be prevented by the infusion of insulin (0.1 mU/kg min). There was a significant inverse correlation between the logarithm of Ra and that of IRI (r = 0.83) and an even stricter correlation between Ra and the logarithm of the molar ratio of IRG/IRI (r = 0.96). It is concluded that the main role of exercise-induced hypoinsulinemia is to increase hepatic glucose production by increasing the sensitivity of the liver to glucagon. Glucose utilization of the working muscle is dominated by the increased activity of hexokinase (s), and physiologic changes of plasma insulin have little effect On it.
Cytotoxic Activation of Complement by Mouse Pancreatic Islet Cells
Authors: Idahl Lars-Åke , Sehlin Janove , Täljedal Inge-Bert , Thornell Lars-Eric
Published: September 2013

Human serum, or serum proteins excluded by Sephadex G-25, irreversibly inhibited the ability of mouse pancreatic islet cells to accumulate Rb+. The same treatment reduced the capacity of serum to subsequently inhibit Rb+ uptake by fresh islet cells or to lyse sensibilized sheep erythrocytes. Serum-treated islet cells exhibited electron microscopic signs of damage, including ruptures of the plasma membrane, swelling of mitochondria, and reduced electron density of the cytoplasmic ground substance. Serum induced a prompt insulin release, which was not inhibited by epinephrine. The serum effects were prevented by mild heating (50°C or 56°C, 30 min) but not by treating serum with 10 mM EGTA and 10 mM MgCl2, or with soybean trypsin inhibitor. Inhibition of Rb+ accumulation in response to human serum was also observed with dispersed mouse exocrine pancreas, liver, and spleen cells but not with whole islets. Homologous mouse serum had no effect on mouse liver or spleen cells but significantly decreased the Rb+ uptake by mouse islet cells. Autologous serum had no noticeable effect. It is suggested that mouse islet cells can activate complement via the alternative pathway and that triggering of this pathway is controlled by cellular discriminators of species, organ, and self.
Studies on the Insulin Mediator: II. Separation of Two Antagonistic Biologically Active Materials from Fraction II
Authors: Cheng Kang , Galasko Gail , Huang Laura , Kellogg Joan , Larner Joseph
Published: September 2013

Insulin treatment significantly altered the elution profile of deproteinized muscle extracts chromato-graphed on Sephadex G-25 columns, particularly in fraction II, which contains the insulin mediator. Further purification of fraction II by high-voltage paper electrophoresis at pH 1.9 and 3.5 resulted in two active fractions. Fraction 1 → 4 stimulated the cyclic AMP-dependent protein kinase and inhibited glycogen synthase phosphoprotein phosphatase, and may be a novel substance. Fractions 1 → > 6 and 3 → 6 inhibited the cyclic AMP-dependent protein kinase and stimulated glycogen synthase phosphatase. It is proposed that the insulin mediator is present in fractions 1 → 6 and 3 → 6.
Rapid Changes in Calcium Content of Rat Pancreatic Islets in Response to Glucose
Authors: Ribes Gerard , Siegel Eberhard G , Wollheim Claes B , Renold Albert E , Sharp Geoffrey W G
Published: September 2013

To study whether glucose affects total islet Ca content, 45Ca content was measured in isolated pancreatic islets, loaded with 45Ca++, during up to 48 h in tissue culture conditions. In islets maintained in 2.8 mM or 8.3 mM glucose the 45Ca content did not increase further after 24 h, indicating that, at this time point, islets are in isotopie equilibrium. Islets maintained in 8.3 mM glucose had a significantly higher Ca content of 9 pmol/islet than the 5 pmol of islets maintained in 2.8 mM glucose.

An increase in the glucose concentration from 2.8 mM to 8.3 mM after 24 h, in the continued presence of 45Ca++, caused a significant and rapid augmentation of the Ca content (+ 2.5 pmol/islet/5 min). Conversely, a decrease of the glucose concentration from 8.3 mM to 2.8 mM resulted in a rapid loss of cellular Ca. Thus, glucose rapidly affects the total Ca content of islets, the turnover of Ca amounting to approximately 10% of the total content per minute.

Islets maintained in 8.3 mM glucose for 24 h exhibited a greater insulin release in response to 16.7 mM glucose than islets maintained for 24 h in 2.8 mM glucose. The increased response, however, was not correlative with the difference in Ca content.
Prevention of Insulin Aggregation by Dicarboxylic Amino Acids During Prolonged Infusion
Authors: Bringer Jacques , Heldt Anneliese , Grodsky Gerold M
Published: September 2013

The dicarboxylic amino acids, aspartic acid and glutamic acid, at their isoelectric pH, reduced aggregation of insulin solutions in vitro for 16 days during continuous agitation at 37°C. Unprotected insulin solutions, when infused via a 14-day impiantatile infusion device in diabetic Chinese hamsters, controlled plasma glucose levels for only 2 days, followed by escape coincident with insulin aggregation. However, when insulin solutions were protected with glutamic acid, euglycemia was maintained for the 14-day life of the device.
Glucagon Immunoreactivity and Antidiabetic Action of Somatostatin in the Totally Duodeno-Pancreatectomized and Gastrectomized Human
Authors: Bringer Jacques , Mirouze Jacques , Marchal Georges , Pham Tan Chi , Luyckx Alfred , Lefebvre Pierre , Orsetti André
Published: September 2013

Ten patients who had been totally duodeno-pancreatectomized and totally (N = 1) or partially gastrectomized (N = 9) for chronic pancreatitis (N = 9) or pancreatic carcinoma (N = 1) were investigated. None had a measurable basal level of either plasma C-peptide or a C-peptide response to i.v. glucagon. Immunoreactive glucagon (IRG) was present in all patients, and the mean level (69 ± 8 pg/ml) was not significantly different from the mean observed in normal subjects (81 ±16 pg/ml). Plasma IRG was unequivocally stimulated by arginine in 2 of the 10 subjects. The effect of somatostatin on plasma glucose and IRG during an oral glucose tolerance test was studied in 5 of the 10 patients. The effects of somatostatin on spontaneous hyperglycemia, plasma growth hormone, and IRG after withdrawal of insulin treatment was studied in 4 patients. Somatostatin blunted both the hyperglycemic and paradoxical IRG responses to the glucose challenge, and reduced the spontaneous rise of blood glucose that occurred after insulin withdrawal. This latter effect was not related to clear-cut changes in plasma growth hormone or in IRG. These data confirm the existence of circulating IRG in pancreatectomized patients and demonstrate the presence of circulating IRG in a completely gastrectomized and pancreatectomized patient. The somatostatin-induced improvement in glucose tolerance in the oral glucose tolerance test seems to be related to a reduction of the paradoxical IRG response. In contrast, the inhibition by somatostatin of the rise in blood glucose which occurs after insulin withdrawal does not seem to be mediated through IRG or growth hormone.
Abnormalities of Pancreatic Somatostatin Secretion Corrected by In Vivo Insulin Treatment of Streptozotocin-Diabetic Rats
Authors: Trimble Elisabeth R , Gerber Pietro P G , Renold Albert E
Published: September 2013

In islets removed from untreated streptozotocin-diabetic rats, the somatostatin-containing cells were unresponsive to changes in glucose concentration, while they did respond to raised cyclic AMP levels. By contrast, in vivo insulin treatment restored the glucose sensitivity of the somatostatin secreting cells. In addition, in vivo insulin treatment resulted in a lowering of the high basal somatostatin secretion rate found in islets from untreated diabetic rats. These changes were made without any alteration of islet insulin content or enhancement of the in vitro insulin secretion. These results indicate that there is not a basic defect in the glucoreceptor of the somatostatin cell in diabetes.
Prevalence of Antibodies to Nucleic Acids in Insulin-dependent Diabetics and Their Relatives
Authors: Huang Shih-Wen , Haedt L Hallquist , Rich Stephen , Barbosa Jose
Published: September 2013

We have studied nucleic acid antibodies in 23 insulindependent diabetics, 27 of their first degree relatives, and 23 normal, unrelated controls. We have found a significantly increased prevalence of antibody to ss-DNA, ds-RNA (reovirus), and synthetic RNA (Poly A · Poly U, Poly I · Poly C) in the unaffected relatives as well as in the diabetics when compared with normal controls. There was no relationship in HLA.
Demonstration of Glucagon in the Stomach of Human Fetuses
Authors: Ravazzola Mariella , Unger Roger H , Orci Lelio
Published: September 2013

Electron microscopy using antiglucagon or antiglicentin antisera and the protein A-gold (pAg) technique revealed a population of immunoreactive cells in the gastric mucosa of human fetuses. The secretory granules of these cells showed the same ultrastructural characteristics and the same labeling pattern as pancreatic α-granules. These data demonstrate that the stomach of human fetuses contains cells with secretory granules indistinguishable by morphologic and immunocytochemical criteria from the pancreatic Acells.
Erythrocyte and Monocyte Insulin Binding in Man: A Comparative Analysis in Normal and Disease States
Authors: Dons Robert F , Ryan Janice , Gorden Phillip , Wachslicht-Rodbard Helena
Published: September 2013

Blood cells have been widely used to evaluate the status of the insulin receptor in man. The insulin receptor of human monocytes has been shown to mirror pathophysiologic states of insulin receptors in target tissues of animal models. Thus, comparison of the properties of the insulin receptor studied simultaneously in erythrocytes and monocytes is appropriate. We studied 19 normal subjects and 32 patients with diverse conditions such as acromegaly, insulinomas, insulin-dependent diabetes mellitus, corticosteroid administration, and the Type A and B forms of insulin resistance. We find that specific insulin binding at tracer concentrations significantly correlate (P < 0.001) for the two cell types obtained from these individuals. However, the total number of binding sites (Ro) and affinity of the receptor at the lowest insulin concentration (Ke) do not significantly correlate (P < 0.1). Monocytes from patients with the Type A and B forms of insulin resistance exhibit marked alterations in insulin binding and simultaneous studies in erythrocytes reflect these changes. The administration of 40 mg/day of prednisone for 3 days to normal subjects produced no significant change in insulin binding to either cell type. Insulin binding to both cell types from poorly controlled insulin-dependent diabetes mellitus patients was similarly normal or elevated. However, improved control decreased insulin binding in monocytes, but not in erythrocytes. We conclude that there is a general relationship between monocyte and erythrocyte insulin binding, but important differences exist in the way their insulin receptors are regulated. Insulin binding in erythrocytes is inversely and exponentially related to cell age. Unlike erythrocytes, monocytes represent a more uniform population of cells capable of the same receptor-mediated endocytotic functions as hepatocytes. Thus, the monocytemay provide a clearer reflection of the insulin receptor status in target tissues.
Effects of Acute Experimental Diabetes on Composite Energy Metabolism in Peripheral Nerve Axons and Schwann Cells
Authors: Greene Douglas A , Winegrad Albert I
Published: September 2013

Rabbit tibial nerve fascicle and endoneurial preparations were used to study the effects of alloxan diabetes on composite energy metabolism in peripheral nerve axons and Schwann cells. Glucose was preferentially used for energy provision in fascicle and endoneurial preparations from diabetic rabbits (despite very high endogenous fructose concentrations) and respiration provided the preponderant fraction of their energy requirements. Diabetic fascicles incubated with 20 mM glucose maintained a steady state of energy metabolism for 2 h, as assessed by O2 uptake , ATP levels, and P-creatine/creatine ratio. Their steadystate rate of energy utilization was estimated from the theoretical yield of ATP from the rates of glucose utilization required to sustain the steady state O2 uptake and lactate production. This was equivalent to the use of 117 mmol ATP/kg/h, a value 26% lower than in normal fascicles, but the ATP levels and P-creatine/creatine ratios in diabetic fascicles were unaltered. Diabetic endoneurium maintained a near steady state of energy metabolism when incubated with 5 mM glucose; its rate of energy utilization was 31% lower than in normal endoneurium, although their ATP levels and P-creatine/creatine ratios were similar. Experimental diabetes results in a striking decrease in the composite steady-state rate of energy utilization in axons and Schwann cells, suggesting that the rates of specific energy requiring processes operative in normal nerve are decreased. Diabetic fascicles and endoneurium had significantly decreased myo-inositol and creatine + P-creatine concentrations, suggesting that the maintenance of the normal intracellular/extracellular gradients of myo-inositol and creatine is impaired. The rate of energy utilization in normal endoneurium was not altered by incubation with 20 mM glucose for 2 h. Insulin (100 μU/ml) did not increase the rate of energy utilization in diabetic endoneurium incubated with glucose.
Simultaneous Inhibition of Insulin and Somatomedin-C Binding to Cultured IM-9 Lymphocytes by Naturally Occurring Antireceptor Antibodies
Authors: Rosenfeld Ron G , Baldwin David , Dollar Laura A , Hintz Raymond L , Olefsky Jerrold M , Rubenstein Arthur
Published: September 2013

A 53-yr-old male patient with insulin-resistant diabetes was found to have circulating inhibitors of both insulin and somatomedin-C binding. Serum obtained from the patient at the time of initial presentation inhibited 50% of both 125I-insulin and 125I-SM-C binding to IM-9 lymphocytes at dilutions of 1:150. Spontaneous improvement in the patient's diabetic state was associated with a simultaneous and equal decrease in the serum inhibitory titers for both radioligands. Scatchard analysis indicated that the observed serum-induced decrease in both insulin and SM-C binding was due to decreased receptor affinity, with no alteration in receptor number. The serum inhibitors of both insulin and SM-C binding were precipitated equally by Staph-A and also by 40% ammonium sulfate, suggesting they were immunoglobulins. The observation of naturally occurring autoantibodies against both the insulin and SM-C receptors suggests a structural homology between the two receptors.
Colchicine and Insulin Secretion in Man
Authors: Giugliano Dario , Cerciello Teresa , Passariello Nicola , Torella Roberto , Saccà Luigi , Sgambato Saverio , D'onofrio Felice
Published: September 2013

The present study is aimed at investigating the effect of acute and chronic colchicine administration on insulin secretion in humans. Acute insulin response to glucose (0.33 g/kg) was significantly decreased by colchicine (3 mg i.v.). In fact, this response (mean change 2–10 min insulin) was 44 ± 8 μU/ml before and 32 ± 6 μU/ml after colchicine administration (P < 0.01). As a consequence of this, glucose disappearance rates were reduced (P < 0.05). Infusion of lysine acetylsalicylate (LAS), an inhibitor of endogenous PG synthesis, completely reversed the inhibitory effect of colchicine upon insulin secretion and also augmented acute insulin response to glucose (response before colchicine + LAS = 45 ± 8 μl/ml; response after colchicine + LAS = 51 ± 9 μl/ml, P < 0.05). This effect was associated with an increase in glucose disappearance rates (P < 0.05). The 10-day treatment with colchicine (2 mg daily) caused a significant suppression of insulin secretion induced by oral glucose (100 g) and significantly increased the plasma glucose concentrations following the test (P < 0.05). These findings demonstrate that (1) both acute and chronic colchicine administration inhibit glucose-induced insulin secretion and deteriorate glucose tolerance in humans, and (2) LAS completely reverses these negative effects of colchicine. An increased synthesis of endogenous PGE, which are known to inhibit insulin secretion in humans, might account for the inhibiting effect of colchicine on insulin secretion.
Correlation Between the Nature and Amount of Carbohydrate in Meal Intake and Insulin Delivery by the Artificial Pancreas in 24 Insulin-dependent Diabetics
Authors: Slama Gérard , Klein Jean-Claude , Delage Anne , Ardila Enrique , Lemaignen Hervé , Papoz Laure , Tchobroutsky Georges
Published: September 2013

We have studied the effects of mixed meals and dextrose intake on blood glucose and insulin delivery by the artificial pancreas in 24 insulin-dependent diabetics. A group of 12 patients had 3 mixed meals containing at random 20, 40, and 60 g of complex carbohydrate along with protein and fat; another group of 12 diabetics, comparable in weight, age, and duration of diabetes, received at random 20, 40, and 60 g of dextrose.

Dextrose ingestion led to a higher initial blood glucose increase than did the mixed meal, but the duration of blood glucose increase lasted significantly longer after the mixed meal than after the dextrose load. The areas under the curves of hyperglycemia were not significantly different. There was a high (but not linear) correlation between the total amount of insulin delivered in order to restore initial blood glucose values and the amount of CHO consumed. There was no correlation with age, body weight, duration of diabetes, nor with the nature and order of administration of the CHO load; 5.1 ± 1.6 to 13.7 ± 2.1 units of insulin were needed for a period of 94 ± 11 to 132 ± 11 min. It is suggested that some of the data obtained in this study might be useful in the programming of an open-loop insulin infusion system.
Decrease of Pancreatic Somatostatin in Neonatal Nesidiobiastosis
Authors: Bishop A E , Polak J M , Garin Chesa P , Timson C M , Bryant M G , Bloom S R
Published: September 2013

The inappropriate insulin release that is characteristic of severe neonatal hypoglycemie and nesidiobiastosis was thought to be principally due to a marked proliferation of B-cells. A possible deficiency of somatostatin, one of the factors controlling insulin release, has only recently been considered.

We report here a significant decrease of pancreatic somatostatin cells and somatostatin content in nesidiobiastosis, as compared with appropriate controls.

Pancreatic tissue from five babies with severe hypoglycemie, hyperinsulinemia, and nesidiobiastosis was examined for insulin, somatostatin, and glucagon by immunocytochemistry and radioimmunpassay. There was a variable insulin cell hyperplasia among the nesidioblastotic specimens but no significant difference from controls was detected. In contrast, there was a consistent and highly significant (P < 0.02) decrease (of more than 50%) of somatostatin cells (controls, 1.29 ± 0.22%; nesidiobiastosis, 0.53 ± 0.14%, mean ± SEM).

Similarly, there was no significant alteration in insulin content, although a slight increase was found in non-microadenomatous areas of the diseased pancreata (controls, 42.3 ± 4.1; nesidiobiastosis, 58.6 ± 9.4 nmol/g wet weight of tissue, mean ± SEM). However, somatostatin content was almost 60% below control values (controls, 0.365 ± 0.038; nesidiobiastosis, 0.16 ± 0.039 nmol/g), a statistically significant difference (P < 0.01).

Thus, a marked reduction in the content of somatostatin was present in the pancreata of these infants with nesidiobiastosis, resulting in a distinct alteration of the normal pancreatic hormone balance.
Comparison of Clinical Course and Sequential Electrophysiological Tests in Diabetics with Symptomatic Polyneuropathy and its Implications for Clinical Trials
Authors: Greene Douglas A , Brown Mark J , Braunstein Seth N , Schwartz Stanley S , Asbury Arthur K , Winegrad Albert I
Published: September 2013

The use of electrophysiological (EP) tests as the primary basis for determining outcome in clinical trials of therapy for symptomatic diabetic polyneuropathy, and the frequently short duration of such trials, is based on assumptions at variance with the pathology and natural history of this disorder and with the evidence that the commonly employed EP tests predominantly reflect the status of the large myelinated nerve fibers. The course of painful, distal symmetrical, primarily sensory polyneuropathy was studied in nine chronic diabetics, aged 21-59 yr, selected for the absence of other forms of diabetic neuropathy, other causes of neuropathy, and other significant illness. All were treated with modifications of diet, insulin, and a daily multivitamin tablet, and, on a randomized basis, also received either placebo or myo-inositol tablets. Initially, and after 2, 4, and 6 mo, a standardized questionnaire was used to assess symptoms, and a standardized neurological examination and battery of EP tests were performed. A minimum of 6 mo was found necessary to assess the clinical course of this syndrome. Clinical improvement occurred in both legs and arms in four patients, as judged by improvement both in symptoms and in the extent of deficits in pinprick and temperature perception; abnormalities in sensory modalities mediated by large myelinated fibers, however, were generally unaltered after 6 mo. A nonuniform distribution of abnormal EP tests of sensory components of the commonly studied nerves of the leg and arm was demonstrated in the study group at the outset, and clinical improvement was not accompanied by evidence of any consistent pattern of improvement in the initially abnormal EP tests. A significant fraction of chronic diabetics with painful, distal symmetrical, primarily sensory polyneuropathy selected by standard criteria appear to have potential for clinical improvement over 6 mo, but primarily in sensory modalities that make it inappropriate to use the common EP tests as the primary basis of judging outcome.
Diabetic Macroangiopathy and Growth Hormone
Authors: Ledet Thomas
Published: September 2013

The large vessel disease develops slowly and progressively among most diabetics. According to the concept of a specific diabetic macroangiopathy, the alterations in the large vessels are part of the general diabetic angiopathy and are different from the spotty atherosclerosis. This hypothesis proposes that the changes develop as a consequence of the metabolic situation in diabetes. The concept is based on epidemiologic, clinical, and patho-anatomical observations.

A model of large-vessel disease in diabetes is briefly described. Diabetic serum causes proliferation of the aortic myomedial cells in culture. Growth hormone causes a similar proliferation. Type I procollagen and fibronectin elaboration is enhanced by diabetic serum. The same effect has been found with growth hormone. Insulin treatment in experimental diabetes prevents the proliferation of arterial myomedial cells in the coronary arteries. The presented data are compatible with the concept of a diabetic macroangiopathy distinct from atherosclerosis.
The Endothelial Cells of Large and Small Blood Vessels
Authors: Zetter Bruce R
Published: September 2013

Recent progress on the isolation and culture of capillary endothelial cells has allowed comparison of the biochemical and physiologic properties of endothelial cells from large and small blood vessels. These cells share certain common features including monolayer formation, production of Factor VIII antigen, production of prostacyclin, and presence of Weibel-Palade bodies. Endothelial cells from capillaries, however, differ from the endothelial cells of large arteries and veins in their nutritional requirements and in their responses to growth and migration stimuli. The differences found between endothelial cells from large and small blood vessels underscore the importance of using cells derived from vessels of appropriate size when studying the macro- and microangiopathies associated with diabetes.
Herpesvirus-induced Atherosclerosis
Authors: Fabricant Catherine G
Published: September 2013

Atherosclerosis extraordinarily like the chronic human disease was reported as a consequence of Marek's disease herpesvirus (MDV) infection in specific pathogen-free (SPF) chickens. This arterial disease was induced not only in hypercholesterolemic but also in normocholesterolemic chickens by infection with MDV. Neither uninfected hypercholesterolemic nor normocholesterolemic SPF chickens developed this arterial disease. Repeated experiments have demonstrated that these results are reproducible. Grossly visible and microscopic atherosclerotic lesions were found in aortas, as well as coronary, brachiocephalic, celiac, gastric, and mesenteric arteries. Microscopic lesions were characterized by fibromuscular intimal thickening with fibrous caps overlying atheromatous change. Results of a pathogenesis experiment indicated that the earliest microscopic and gross arterial lesions occurred respectively at 1 and 3 mo post-MDV-infection. An additional important link established between infection and arterial lesions was the finding of specific MDV internal antigens in smooth muscle cells (SMC) of some medial layers of all arterial segments examined throughout the time span of lesion development (7 mo). Furthermore, lipid accumulations in arterial lesions of normocholesterolemic infected chickens and in cultured (chicken) arterial SMC suggest that a major mechanism in MDV atherosclerosis may be viral-induced alteration of cellular lipid metabolism. The distribution and morphologic character of MDV-atherosclerotic lesions closely resemble the chronic human arterial disease. Because humans are known to be widely and persistently infected with as many as five herpesviruses, these results may be particularly relevant to human atherosclerosis. Furthermore, since diabetes is an identified high risk factor of atherosclerosis, these findings may also be important in diabetes.
The Fluid Phase of Coagulation and the Accelerated Atherosclerosis of Diabetes Mellitus
Authors: Jones R L , Peterson C M
Published: September 2013

The early and accelerated atherosclerosis associated with diabetes mellitus is probably multifactorial in origin. Hyperglycemia, in addition to its numerous pathologic effects on lipids, hormonal profiles, the vascular tree, and platelets, is also associated with effects on the fluid phase of coagulation. The most striking abnormality of coagulation described in diabetes mellitus is a decrement in fibrinogen survival that is rapidly reversible with correction of hyperglycemia or the administration of heparin but not with aspirin and dipyridamole administration, suggesting a hypercoagulable state. Abnormalities of clotting factor assays and circulating levels have been reported in patients with diabetes mellitus, but most of these studies are complicated by the controversy over the results being due to diabetes mellitus or due to the presence of vascular lesions concomitant with diabetes. Nevertheless, an increasing amount of evidence implicates the participation of the fluid phase of coagulation in both the initiation and propagation of diabetic vascular complications.
Tissue Differences in Insulin Receptors: Acute Changes in Insulin Binding Characteristics Induced by Wheat Germ Agglutinin
Authors: Pottick Lorelle A , Moxley Richard T , Livingston James N
Published: September 2013

The plant lectin, wheat germ agglutinin (WGA), produced differential effects on insulin binding by insulin receptors from rat adipocytes, rat liver, human placenta, and human monocytes. Treatment of adipocyte membranes with WGA (1 μg/ml) markedly enhanced insulin binding (500% of control, 100%) conducted with 5 × 10-10 M 125I-insulin. The lectin's effect on insulin binding by liver membranes was significantly less (260% of control) and required a larger WGA concentration (5 μg/ml) to produce the stimulation. Insulin binding by placental membranes was increased only slightly (140%) by WGA, and monocytes failed to respond. The rate of insulin dissociation from the membrane preparations was decreased by lectin treatment. This effect was most prominent with adipocyte membranes, followed next by liver membranes, whereas only a slight inhibition was found with placental membranes. Scatchard analysis of the adipocyte receptor binding data indicated that WGA treatment completely linearizes the normally curvilinear plot to one high-affinity component (Kd of 0.22 nM) and decreases total insulin binding capacity by 60%. Similar effects were found with liver membranes, except that the extent of the changes was not as dramatic. WGA treatment did not linearize the Scatchard plot determined for placental membranes. Adipocyte and liver receptors solubilized by Triton X-100 responded to WGA, although the response was less in the former (350% above control, 100%) and greater in the latter (500%). Solubilization of placental receptors did not improve their response to the lectin. These results suggest differences in the structure of the insulin receptors from different tissues. Furthermore, the effects of WGA on adipocyte and liver receptors indicate the potential usefulness of this lectin in studies of acute changes in the the insulin binding properties of these insulin target tissues.
Hormone Regulation of Glucose Metabolism in the Genetically Obese-Diabetic Mouse (db/db): Glucose Metabolism in the Perfused Hindquarters of Lean and Obese Mice
Authors: Chan Timothy M , Dehaye J P
Published: September 2013

Glucose metabolism and insulin sensitivity in the skeletal muscle of genetically obese-diabetic mice (db/db) 5-6 wk of age (an early stage of the diabetes-obesityc syndrome) were examined using an in situ perfused hindquarter preparation. Rates of glucose uptake, 14CO2 production from (U-14C) glucose, and lactate production from glucose were all lower in muscles from dbldb mice than those from their lean littermates. Lactate production in muscle perfused without exogenous glucose was similar in both lean and obese mouse hindquarters. Likewise, epinephrine, which activated phosphorylase equally in both lean and obese mouse muscle, also elevated the tissue glucose-6-phosphate level and lactate production from endogenous source(s) to a similar degree in the two preparations. However, epinephrine was less effective In stimulating glucose uptake in the db/db mouse preparation.

Glucose uptake was lower in the obese mouse hindquarter at all insulin concentrations tested (0-1000 μU/ml). The half-maximally effective dose of insulin (50 μU/ml) remained unaltered, however, indicating a decrease in insulin responsiveness rather than sensitivity. Both basal and insulin (1 mU/ml)-stimulated (3H)-D-allose uptake In the dbldb mouse hindquarter were below normal. No difference in assayed hexokinase activity was observed. Muscle pyruvate dehydrogenase and glycogen synthase activities were elevated by insulin (1 mU/ml) to a similar extent in both lean and obese mice.

These findings suggest that at an early phase of development when obesity, hyperglycemia, and hyperinsulinemia are moderate, a defect in glucose transport plays a major role in the “insulin resistance” of the skeletal muscles of dbldb mice.
Production of Monoclonal Antibodies Reacting with Rat Islet Cell Membrane Antigens
Authors: Eisenbarth George S , Oie Herbert , Gazdar Adi , Chick William , Schultz Julie A , Scearce Richard M
Published: September 2013

The present communication describes the generation of twelve lymphocyte hybrid cell lines whose antibodies react with the rat islet cell line RIN, and the initial characterization of the tissue specificity and functional properties of these antibodies. Since antibodies recognizing islet cell differentiation antigens were sought, these permanent hybrid cell lines were developed from cultures whose antibodies, by radioimmunoassay, bound minimally or not at all to rat red blood cells (cell line A3C1 is an exception). Antibodies from five of the cell lines by radioimmunoassay react significantly with cultured rat fibroblasts in addition to their reaction with RIN cells. Antibody F41-5D6 by indirect immunofluorescence reacted with sections of the RISL transplantable islet cell tumor and specifically with islet cells in sections of rat pancreas. Four antibodies (F41-1G3, 5B5, 6C5, and 5A5), by indirect immunofluorescence, reacted with sections of the RISL transplantable islet cell tumor but not with sections of normal pancreas. Seven of the antibodies were cytotoxic to cultured RIN cells and seven antibodies share the useful property of reacting with protein A. This study demonstrates the feasibility of producing monoclonal antibodies to islet cell differentiation antigens and describes several antibodies which should be useful reagents in studies of the physiology and pathophysiology of the islet cell plasma membrane.
Block in Insulin Release from Column-Perifused Pancreatic β-Cells Induced by Islet Cell Surface Antibodies and Complement
Authors: Kanatsuna Takahiro , Lernmark Ake , Rubenstein Arthur H , Steiner Donald F
Published: September 2013

Dispersed rat pancreatic islet cells were mixed into a short column of Bio-Gel P-2 polyacrylamide beads and perifused with an antiserum containing islet cell surface antibodies. The release of radioactive chromium from prelabeled cells, as a measure of cell membrane permeability, was not affected by cell surface antibodies alone, but increased dramatically in the presence of complement. While there was an eightfold increase in glucose-stimulated insulin release from β-cells exposed to control serum and complement, insulin release was completely blocked from β-cells exposed to islet-cell-specific antibodies and complement. These findings suggest that islet cell surface antibodies can mediate complement-dependent cytotOXicity.
Uptake of Glucose into the Intestine of Diabetic Rats: Effects of Variations in the Effective Resistance of the Unstirred Water Layer
Authors: Thomson A B R
Published: September 2013

Diabetes mellitus in rats is associated with enhanced intestinal absorption of glucose, but the kinetic basis for this observation is disputed. Only recently has it been appreciated that failure to account for the resistance of the unstirred water layer (UWL) leads to gross errors in the estimation of the kinetics of active and passive transport. Accordingly, the uptake Jd (unidirectional flux rate) of glucose into the intestine was measured in alloxan- or streptozotocin-diabetic rats (DM) and in control animals (C) under conditions selected to yield low and high UWL resistance. When the UWL resistance was minimized by stirring the bulk phase, Jd was higher in DM than in C, but only from the higher concentrations of glucose; this difference between DM and C was obscured when UWL was high. The difference between C and DM in Jd from 40 mM glucose progressively increased from 3 to 83 days after induction of DM, and was present in the jejunum and ileum as well as in young and old animals. The Jd from 0.5 to 2 mM glucose was similar in DM and C, and the inhibitory effect of galactose on Jd of glucose was similar in DM and C. Jd was higher in DM than in C for L-glucose and for D-glucose in the presence of phlorizin and in the absence of sodium ion. Kinetic analysis demonstrated a higher maximal transport rate (Jd m) and apparent passive permeability coefficient (P*) in DM than in C, but the apparent affinity constant was unchanged. It is concluded that (1) the greater Jd of glucose in DM is due to a greater Jdm and P*, rather than due to changes in the properties of the glucose carrier itself, and (2) these differences may be obscured by variations in UWL
Decreased Stimulated Glucose Oxidation and lodination by Polymorphonuclear Leukocytes from Insulin-Treated Diabetic Subjects
Authors: Qvist Rajes , Larkins Richard G
Published: September 2013

To investigate the mechanism of the reported abnormality of polymorphonuclear leukocyte (neutrophil) function in diabetes, the burst of oxidative activity accompanying the killing reaction and the neutrophil iodination reaction were measured in 21 stable, insulintreated diabetic subjects and 32 nondiabetic subjects of similar age range. Responses to standard killed preparations of Candida albicans (C. albicans) (glucose oxidation and neutrophil iodination) and Staphylococcus aureus (S. aureus) (neutrophil iodination) were studied. The iodination reaction was studied using the subjects' neutrophils suspended both in autologous serum and in pooled normal human serum, and the glucose oxidation test was performed using the neutrophils in pooled normal human serum.

There was a significant decrease in the conversion of 14C-1-glucose to 14CO2 in the neutrophils from diabetics [0.47 ± 0.04 (SE) cf. 0.64 ± 0.04 nmol/2 × 106 neutrophils/60 min, P < 0.005] and in neutrophil iodination in response to S. aureus in both autologous serum (diabetics .089 ± 0.008 cf. 0.114 ± 0.008 nmol iodine/106 neutrophils/90 min, P < 0.025) and in pooled human serum (diabetics 0.086 ± 0.009 cf. 0.105 ± 0.006, P < 0.05). There was no significant difference in neutrophil iodination in response to C. albicans. There was a significant negative correlation between the diabetics' fasting plasma glucose level and neutrophil iodination in response to S. aureus in pooled human serum (r = - 0.54, P < 0.05), but not between fasting plasma glucose and glucose oxidation.

It is concluded that there are significant decreases in stimulated glucose oxidation and in the neutrophil iodination reaction (reflecting decreased function of the myeloperoxidase-hydrogen peroxide-halide microbicidal system) in neutrophils from insulin-treated dia-betic subjects. These abnormalities may contribute to the defective bactericidal activity of diabetic neutrophils.
The Insulin Gene Is Located on the Short Arm of Chromosome 11 in Humans
Authors: Owerbach David , Bell Graeme I , Rutter William J , Brown Judith A , Shows Thomas B
Published: September 2013

The human insulin gene has been previously localized to chromosome 11. We have analyzed the human ONA sequences present in a human-mouse somatic cell hybrid line possessing a translocation involving human chromosomes 11 and X. These data indicate that the human insulin gene is located on the short arm of chromosome 11 in the region p13→pter.
Albumin Deposition in Dermal Capillary Basement Membrane in Insulin-dependent Diabetes Mellitus: A Preliminary Report
Authors: Chavers Blanche , Etzwiler Donnell , Michael Alfred F
Published: September 2013

Skin specimens obtained from 24 insulin-dependent diabetics (IDD) and 35 controls were examined by immunofluorescence (IF) microscopy. An increased percentage (>8%) of dermal vessel basement membranes (BM) showing circumferential fluorescence for albumin was observed in 18 of 24 IDD (duration of diabetes 1.5–33 yr) and 1 of 35 controls. Dual label studies using fluorescein-conjugated anti-human albumin and rhodamine-conjugated anti-human BM confirmed that localization of albumin was within the BM. These studies suggest that increased albumin localization in extracellular BM may be widespread in diabetes.
Functional Evaluation of a Bioartificial Pancreas Using Isolated Islets Perifused with Blood Ultrafiltrate
Authors: Reach Gérard , Poussier Philippe , Sausse André , Assan Roger , Itoh Mitsuyasu , Gerich John E
Published: September 2013

A new bioartificial pancreas, in which rat islets within a Millipore chamber are perifused with blood ultrafiltrate (polyacrylonitrile membrane), has been developed and its function evaluated in vitro and in vivo. Use of ultrafiltration (instead of diffusion) permitted rapid transmission of changes in blood glucose to the islet compartment (less than 10 min). To determine whether ultrafiltrate of Krebs-Ringer bicarbonate buffer (KRBB) and blood could support normal islet Bcell function, insulin secretion of freshly isolated islets in response to a 20-mM glucose challenge was examined during perifusion with KRBB and then with ultrafiltrate produced either from KRBB itself or from blood of normal and streptozotocin-induced diabetic rats. In the latter case, perifusate was reinfused to the animals, whose plasma glucose and insulin were then measured.

Insulin responses to glucose were virtually identical when the same islets were perifused with KRBB and then with ultrafiltrate of KRBB (47 ± 12 versus 41 ± 9 ng/100 islets/24 min), or when islets were perifused with KRBB and then with ultrafiltrate produced from blood of normal rats (69 ± 6 versus 73 ± 11 ng/100 islets/24 min). When five diabetic rats were connected to the device containing 600 islets, their plasma glucose decreased from 19.8 ± 1.2 to 6.1 ± 0.5 mM (P < 0.001) within 120 min without overshoot hypoglycemia, and remained normal for up to 6 h. Plasma insulin increased from 2.0 ± 0.1 to 11.4 ± 1.4 ng/ml (P < 0.02) at 30 min and then decreased to 2.9 ± 0.6 ng/ml. After intravenous glucose administration (0.5 g/kg, N = 4), plasma insulin increased twofold within 15 min, and glucose disappearance rates were identical to those obtained in four normal rats (K = 2.13 ± 0.18 versus 2.23 ± 0.09, NS).

These results indicate that ultrafiltrate of KRBB and blood can acutely support normal islet B-cell function, and that ultrafiltration can provide satisfactory glucose-insulin kinetics for an implantable closed-loop insulin delivery system, in which nonsyngeneic islets may be protected against immune rejection.
Autoantibodies Against the Insulin Receptor Recognize the Insulin Binding Subunits of an Oligomeric Receptor
Authors: Kasuga Masato , Obberghen Emmanuel Van , Yamada Kenneth M , Harrison Len C
Published: September 2013

125I-insulin was specifically cross-linked to membranes of human cultured lymphocytes (IM-9 line) using disuccinimidyl suberate. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions and autoradiography of this preparation revealed a major 125I-labeled band with an apparent mol wt of 130,000 and minor bands of about 300,000 and 95,000. Labeling of these bands was inhibited by incubation of membranes with either unlabeled insulin or autoantibodies to the insulin receptor. The bands were also observed after the 125I-insulin cross-linked preparation was solubilized and immunoprecipitated with a panel of autoantibodies to the insulin receptor. However, immunoprecipitation of the 125I-insulin-receptor complex was inhibited by preincubation with excess unlabeled insulin. Finally, 125I-Fab fragments of mol wt 50,000 prepared from anti-receptor antibodies and cross-linked to membranes were resolved into a major complex of mol wt 180,000 and a minor band of 125,000. Neither band was observed when 125I-Fab fragments were cross-linked to membranes in the presence of an excess of unlabeled insulin. These findings indicate that autoantibodies to the insulin receptor are directed against the insulin binding subunits of an oligomeric receptor.