bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyclosporin A for Immunosuppression: Observations in Rat Heart, Pancreas, and Islet Allograft Models and in Human Renal and Pancreas Transplantation
Authors: Rynasiewicz John J , Sutherland David E R , Ferguson Ronald M , Squifflet Jean-Paul , Morrow Charles E , Goetz Frederick C , Najarian John S
Published: September 2013

Cyclosporin A (CsA) is a unique immunosuppressive cyclic polypeptide that is currently being used, either alone or in combination with low-dose prednisone, to treat recipients of renal or pancreas allografts in clinical trials. CsA is very effective in preventing rejection of heart and renal allografts in rodents, but in nontoxic doses does not consistently prevent rejection of pancreas and islet allografts. Therefore, we tested low-dose CsA in various combinations with low-dose prednisone, azathioprine, or total lymphoid irradiation in rat heart, pancreas, and islet allograft models. Several combinations are synergistic and when administered continuously can indefinitely prevent rejection of heart allografts, but only delay rejection of pancreatic allografts, transplanted across a major histocompatibility barrier. CsA by itself prolonged the survival of islet allografts transplanted across a minor, but not a major, histocompatibility barrier. CsA and azathioprine had a synergistic effect in the minor histocompatibility barrler islet transplant model, but, in the nontoxic combinations tested, could not prevent rejection indefinitely. A randomized prospective trial comparing standard immunosuppressive therapy (ALG, prednisone, and azathioprine), with CsA and low-dose prednisone for clinical renal allotransplantation is ongoing at the University of Minnesota. Current actuarial 1-yr graft survival is 93% for CsA-treated patients (N = 48) and 81% for conventionally treated patients (N = 52). Patient survival is 98% for CsA and 100% for conventionally treated patients. A pilot trial of CsA in the clinical pancreas transplant program at the University of Minnesota is also underway. Since 1978, 46 pancreas transplants have been performed in 43 patients. Of 30 technically successful pancreatic allografts, 5 of 12 recipients treated with conventional immunosuppression and 6 of 18 recipients treated with CsA currently have functioning grafts and are insulin independent between 1 and 44 months after transplantation. The results of metabolic studies are similar in conventional and CsA-treated patients with functioning pancreas grafts. Since pancreas grafts may fail for reasons other than rejection, further observations are needed to ascertain the role of CsA in clinical pancreas transplantation.
Insulin-induced Loss of Insulin-like Growth Factor-I Receptors on IM-9 Lymphocytes
Authors: Rosenfeld Ron G , Hintz Raymond L , Dollar Laura A
Published: September 2013

Preexposure of IM-9 lymphocytes to the somatomedin peptide insulin-like growth factor-I (IGF-I) results in a time- and concentration-dependent reduction in specific receptors for IGF-I. Since insulin and proinsulin are structurally homologous to IGF-I, we investigated the ability of insulin analogues to compete for occupancy and to directly modulate IGF-I receptor concentrations.

IGF-I binds rapidly and reversibly to IM-9 cells at 15°C, with half-maximal displacement of 125I-I-IGF-I at IGF-I concentrations of 3.6 × 10−9 M and insulin concentrations of 5 × 10−7 M. Preexposure of cells at 37°C to either IGF-I or insulin produced a concentration-dependent reduction in binding of 125I-IGF-I. A 50% decrease in binding was observed following preincubation of cells with IGF-I at 2.5 × 10−9 M and insulin at 2 × 10−7 M. At higher insulin concentrations (10−6–10−5 M), up to 70% reduction in 125I-IGF-I binding occurred. Bovine proinsulin and guinea pig insulin competed less potently than porcine insulin for the IGF-I receptor, and produced receptor loss in proportion to their ability to occupy the IGF-I receptor. Scatchard analysis indicated that at all insulin concentrations, the decrease in binding was secondary to loss of available IGF-I receptors, with no change in affinity. Receptor loss was evident following 1–2 h preexposure to insulin, with a t½ of 4 h and maximal receptor loss within 10 h. Similarly, IGF-I and IGF-II competed for occupancy of the IM-9 insulin receptor, with 50% displacement of 125I-insulin occurring at peptide concentrations of 3.5 × 10−9 M (insulin), 3.5 × 10−8 M (IGF-II), and 3 × 10−7 M (IGF-I). Preexposure of cells to these peptides at 37°C for 20 h resulted in a concentration-dependent reduction in binding of 125I-insulin, with the order of analogue effectiveness being insulin > IGF-II > IGF-I.

These data emphasize the structural and functional homology of insulin and the somatomedin peptides, IGF-I and II, as well as their respective receptors. Additionally, the data support the conclusion that the insulin and somatomedin peptides not only bind to both receptors, but downregulate each receptor in proportion to their ability to occupy that receptor.
Photoaffinity Labeling of Insulin Receptors in Viable Cultured Human Lymphocytes: Demonstration of Receptor Shedding and Degradation
Authors: Berhanu Paulos , Olefsky Jerrold M
Published: September 2013

A photosensitive derivative of radiolabeled insulin, SANAH-125I-insulin, was prepared by reacting N-succinimidyl-6-(4'-azido-2'-nitrophenylamino) hexanoate (SANAH) with 125I-insulin. Cultured IM-9 cells were incubated with SANAH-125I-insulin at 16 degrees C in the dark. They were then washed, photolyzed, solubilized, and analyzed by SDS-polyacrylamide gel electrophoresis and autoradiography. Under disulfide reducing conditions, a single specific band of Mr 125,000 was obtained. The characteristics of the labeling of this band with SANAH-125I-insulin (specificity, time course, concentration effect) were the same as that of 125I-insulin interaction with the IM-9 cells and the labeling process did not affect cell viability. The solubilized photolabeled insulin receptor fraction was enriched by first adsorbing to agarose-bound wheat germ agglutinin and the material eluted with N-acetyl-D-glucosamine was then analyzed by SDS-PAGE and autoradiography. Under nonreducing conditions, a major receptor band of Mr 320 K and a minor band of 280 K were obtained. Upon disulfide bond reduction with increasing concentrations of dithiothreitol, a major band of Mr 125 K and two minor bands of Mr 210 K and 94 K were seen. When cells photolabeled at 16° were further incubated at 37°, there was a time-dependent loss of intact receptors into the incubation buffer. In contrast, no similar shedding of labeled receptors was observed from isolated rat adipocytes. Following shedding, the labeled IM-9 insulin receptors rapidly disappeared from the incubation buffer (half-time ∼ 1.5 h). These results demonstrate the feasibility of photoaffinity labeling, characterizing, and following the fate of insulin receptor in viable cells. Thus receptor photoaffinity labeling should provide a suitable approach for studies of the biologic fate of insulin receptors in cells that are targets for insulin action.
Effects of Chronic Administration of Sodium 2 Chloropropionate in Normal and Diabetic Dogs
Authors: Ribes G , Valette G , Valette J F , Loubatieres-Mariani M M
Published: September 2013

Pancreatic hormonal and metabolic responses to chronic administration of sodium 2 chloropropionate (2 CP) were investigated in conscious dogs. We subcutaneously administered 2 CP daily for 7 days at the dose of 0.58 mmol/kg (62.5 mg/kg) in normal dogs and those rendered diabetic by injection of alloxan (0.24mmol/kg, i.v.).

In the normal dogs, the chronic administration of 2 CP provoked a decrease in blood lactate and pyruvate but not in blood glucose concentrations. Urinary oxalate was not increased by the daily injection of 2 CP. Blood ketone body concentrations progressively increased after the third day of treatment. At the same time, plasma cholesterol slowly decreased. The 2 CP chronic administration did not change the plasma somatostatin, glucagon, and insulin levels.

In the alloxan-diabetic dogs, treated with insulin alone, blood glucose, ketone body concentrations, and plasma somatostatin and glucagon levels were elevated. The adjunction of 2 CP with insulin injections resulted in a fall in blood lactate and pyruvate levels and a progressive decrease of blood glucose concentrations. Blood ketone bodies, which were already high at the start, were not affected when 2 CP was combined with insulin. The hypersomatostatinemia was not decreased, whereas the hyperglucagonemia was considerably reduced. So, I/G ratio, which was strongly decreased with insulin alone, progressively returned to normal values. As to urinary compounds, 2 CP induced a marked decrease in glucosuria and did not change the elevated urinary βhydroxybutyrate levels.

In conclusion, these findings show that the adjunction of sodium 2 chloropropionate to insulin in diabetic dogs results in a reduction of hyperglycemia and hyperglucagonemia.
Macro- and Micro-Domains in the Endocrine Pancreas
Authors: Orci L
Published: September 2013

Since the invention of the light microscope in the seventeenth century, progress in the field of cell research has been markedly dependent on improvements in the resolving power of magnifying instruments. The limitations of available microscopes must have inspired Martyn Paine of New York City to write in 1840
Reversibility and Preventability of the Decrease in Slow Axonal Transport Velocity in Experimental Diabetes
Authors: Sidenius Per , Jakobsen Johannes
Published: September 2013

The effect of insulin treatment on the slow axonal transport velocity of sciatic nerve was examined in streptozotocin-diabetic rats following the injection of 3H-proline into the fifth lumbar spinal ganglion. Strict insulin treatment, started immediately after the induction of diabetes and continued until the end of the experiment (group 1), can prevent the slowing in transport occurring in untreated diabetic rats [controls 0.98 ± 0.06 mm/day (mean ± SD); untreated diabetic rats 0.83 ± 0.10 mm/day; insulin-treated rats 1.00 ± 0.11 mm/day]. Strict insulin treatment when postponed for 3 wk (group 2), also can reverse an already slowed transport velocity (0.94 ± 0.05 mm/day). In addition, the influence on the transport abnormality of diabetes was studied in a situation where proteins were synthesized during normoglycemia and already in transport at the time of administration of streptozotocin; i.e., 2 days following protein labeling. The mean velocities were identical in rats made diabetic prior to (group 1) or following (group 2) protein labeling (0.83 ± 0.10 m/day and 0.83 ± 0.06 mm/day, respectively), Indicating that the metabolic derangement leads to a decrease in transport all along the axon as soon as the state is induced.

The percentage of TCA-insoluble label in slow component a (SCa) of the transport system was decreased in the three groups with elevated glucose level at the time of pulse-labeling (untreated group 1: 16.9 ± 8.3%; insulin-treated group 1 and 2:11.8 ± 8.1% and 10.3 ± 6.3%, respectively) as compared with rats with normoglycemia (controls: 27.4 ± 13.9% and untreated group 2: 35.1 ± 10.0%).

Thus a normal metabolic state at the time of pulselabeling followed by induction of hyperglycemia (diabetes group 2) results in decreased transport velocity of a normal amount of label, whereas the opposite metabolic situation (insulin-treated groups) leads to a normal transport velocity of a decreased amount of protein. We suggest that SCa is propelled by the continuous delivery of protein from the nerve cell body and, consequently, that the decreased amount of label in SCa as well as its slowed advancement indicate a defect in protein synthesis or in allocation of protein in the cell bodies.
The Immune Response to Insulin in Man: Interaction of HLA Alloantigens and the Development of the Immune Response
Authors: Kahn C Ronald , Mann Dean , Rosenthal Alan S , Galloway John A , Johnson Armead H , Mendell Nancy
Published: September 2013

In both mice and guinea pigs, the immunologic response to insulin has been demonstrated to be under immune response (Ir) gene control. In the present study, we have attempted to identify Ir genes to insulin in man by correlating HLA allotype with immunologic response to insulin. Three groups of patients were studied: (1) 117 diabetic patients with a history of exaggerated immunologic response to insulin (insulin allergy, resistance, or systemic reactions); (2) 95 insulin-taking diabetics without clinically significant immune response; and (3) 109 nondiabetic controls. Determination of HLA alloantigen frequencies in the “insulin allergic” population and the nonallergic diabetics revealed only modest increases of HLA-Bw44 (29% versus 16%, P < 0.05) and -DR7 (28% versus 15%, P < 0.05). Studies of linkage disequilibrium, however, revealed interesting associations involving HLA-A2, -Bw44, and -DR7 in the diabetic with insulin allergy that were not present in the nonallergic diabetic. Combinations of any two or all three of these antigens were observed in 39% of diabetics with insulin allergy but in only 3% of nonallergic diabetics. An intermediate frequency (23%) was observed in the normal population. Thus, if an individual with any combination of HLA-A2, -Bw44, and -DR7 develops diabetes and receives insulin therapy, there is over a 90% probability he will exhibit a clinically significant immune reaction to insulin (calculated relative risk = 20.6). These data suggest that in man, as in the mouse, the immune response to insulin is under genetic control, but this may involve interactions of several genes in the major histocompatibility (MHC) complex, or a locus in linkage with these genes that is not measured by current techniques.
Preventive and Therapeutic Effects of Large-Dose Nicotinamide Injections on Diabetes Associated with Insulitis: An Observation in Nonobese Diabetic (NOD) Mice
Authors: Yamada Kentaro , Nonaka Kyohei , Hanafusa Toshiaki , Miyazaki Atsushi , Toyoshima Hiroyuki , Tarui Seiichiro
Published: September 2013

This experiment was undertaken to explore a novel method of therapy for insulin-dependent diabetes mellitus (IDDM), using nonobese diabetic (NOD) mice that had symptoms and histologic changes similar to those of human IDDM patients. We examined preventive and therapeutic effects of large-dose nicotinamide administration on diabetes in NOD mice. Eighteen young female NOD mice without glycosuria were randomly divided into two groups; nine received subcutaneous nicotinamide (0.5 mg/g body wt) injections every day and the other nine were maintained as a control group and not injected. After 40 days, all of the mice given nicotinamide showed almost normal glucose tolerance and only mild insulitis on histologic study. On the other hand, marked glycosuria and severe insulitis were observed in six of the nine mice not injected. Four of six NOD mice given nicotinamide from the day of the first occurrence of marked glycosuria displayed a disappearance of glycosuria and an improvement in glucose tolerance during the therapy; however, urine sugar became negative in only one of six mice that received nicotinamide from 1 to 2 wk after the onset of marked glycosuria. These results indicate that nicotinamide has preventive and therapeutic effects on diabetes in NOD mice, and suggest the reversibility of B-cell damage, at least at a very early Stage of IDDM.
The Effect of Aldose Reductase Inhibition on Motor Nerve Conduction Velocity in Diabetic Rats
Authors: Yue D K , Hanwell M A , Satchell P M , Turtle J R
Published: September 2013

This study examined the effects of an aldose reductase inhibitor (CP 45634, Sorbinil, Pfizer, New York, New York) on the neuropathy of streptozotocin-induced diabetic rats. Sorbinil treatment for 4 wk reduced sciatic nerve sorbitol concentration and improved motor nerve conduction velocity in diabetes of 2–9 mo duration. It remains to be determined whether Sorbinil can prevent chronic diabetic neuropathy.
Spontaneous Hyperglycemia and Impaired Glucose Tolerance in Athymic Nude BALB/c Mice
Authors: Zeidler Adina , Tosco Clara , Kumar Dinesh , Slavin Bernard , Parker John
Published: September 2013

Basal plasma glucose, glucose tolerance, and insulin secretion were investigated in young and mature athymic nude BALB/c mice and in age-matched controls. Basal plasma glucose levels in male athymic nude mice were similar to those of controls at 1, 3, and 4 wk of age. At 6, 8, and 12 wk of age, male athymic nudes had significantly higher basal plasma glucose levels when compared with controls (P < 0.01). Plasma immunoreactive insulin concentrations were similar in athymic nudes and controls at 1 wk of age, but at 3 wk of age and subsequently at 6, 8, and 12 wk athymic nude mice had significantly decreased insulin levels when compared with their age-matched controls (P < 0.05).

We found impaired glucose tolerance in male athymic nude mice at all age groups when compared with both female athymic nudes and control BALB/c mice.

The discovery of a spontaneous diabetic syndrome (hyperglycemia, impaired glucose tolerance, and decreased insulin secretion) in a colony of athymic nude mice may provide an excellent model for studying the genetics and interactions between the immune and endocrine systems.
Responsiveness of plasma 18-Hydroxycorticosterone and Aldosterone to Angiotensin II or Corticotropin in Nonazotemic Diabetes Mellitus
Authors: Beretta-Piccoli Carlo , Weidmann Peter , Fraser Robert
Published: September 2013

To assess the function of the final step of the pathway for aldosterone biosynthesis, the responsiveness of plasma 18-hydroxycorticosterone and aldosterone concentrations to angiotensin II infusion was studied in 14 patients with nonazotemic diabetes mellitus as compared with 14 normal controls approximately matched for sex and age. In addition, the responses of both steroids to corticotropin injection were investigated in the diabetic patients. Under basal conditions, plasma aldosterone levels were slightly lower in the patients than in normal controls, while plasma 18-hydroxycorticosterone concentrations were similar in the two study groups. Angiotensin II induced marked and comparable increases in plasma 18-hydroxycorticosterone and aldosterone levels in normal and diabetic subjects. Plasma 18-hydroxycorticosterone and aldosterone levels before and after angiotensin II infusion were significantly interrelated; this correlation was similar in normal subjects (r = 0.61; P < 0.001) and diabetic patients (r = 0.51; P < 0.005). Plasma 18-hydroxycorticosterone and aldosterone were significantly increased by corticotropin in the patients. These findings indicate that the terminal step of aldosterone biosynthesis, which involves the production of 18-hydroxycorticosterone and aldosterone, is largely unaltered in patients with nonazotemic diabetes mellitus.
Glucoregulatory Mechanisms Following Hypophysectomy in Diabetic Dogs with Residual Insulin Secretion
Authors: Kemmer F W , Sirek A , Sirek O V , Perez G , Vranic M
Published: September 2013

It is known that in pancreatectomized dogs completely deprived of insulin, hypophysectomy normalizes plasma glucagon and prevents ketoacidosis, but rarely normalizes glucose levels. The present study concerns diabetic dogs with only partial insulin deficiency in whom we studied the effects of hypophysectomy on glucoregulatory mechanisms. Eleven dogs were alloxanized and hypophysectomized 2–3 wk later. Withholding exogenous insulin from alloxan-diabetic dogs resulted in hypoinsulinemia (6 ± 1 μU/ml), hyperglucagonemia (341 ± 44 pg/ml), elevated plasma FFA levels (1442 ±125 μeq/ml), hyperglycemia (333 ± 27 mg/dl), increased hepatic glucose production (Ra, 4.2 ± 0.3 mg/kg/min) and decreased clearance of glucose (CR, 1.8 ± 0.1 ml/kg/min). After hypophysectomy, glucagon and FFA fell to normal in 7 of 11 hypophysectomized alloxan-diabetic dogs (106 ± 7), while 4 remained hyperglycemic (337 ± 28 mg/dl). Normoglycemia was the result of a reduced Ra to subnormal in the presence of unaltered glucose clearance. However, normoglycemia could not be equated with normal metabolism: glucose turnover was well below normal, and peripheral glucose uptake was impaired. The sensitivity of the liver to glucagon was investigated by infusing somatostatin alone (ST, 0.24 μg/kg/min) and with replacement (1 mg/kg/min) or with excess of glucagon (3.6 ng/kg/min). Even in hypophysectomized dogs, glucagon suppression resulted in a sustained decrease in Ra and plasma glucose. Glucagon replacement restored glucose kinetics and excess of glucagon led to hyperglycemia (300 ± 20 mg/dl). This was due to a prompt rise in Ra which, however, plateaued at levels lower than in diabetic dogs, suggesting that normalization of glucagon following hypophysectomy is an important but not the sole factor responsible for the marked reduction in Ra. The persistence of hyperglycemia in four diabetic dogs was attributed to a diminished effect of the hypophysectomy: in spite of hyperglycemia, Ra was not lower than in normoglycemic dogs, it was insensitive to glucagon suppression, and glucose clearance was more impaired than in normoglycemic dogs. It is hypothesized, therefore, that these dogs had a smaller residual insulin reserve than normoglycemic hypophysectomized dogs. Thus a critical amount of insulin may be indispensible for the maintenance of normoglycemia.

In conclusion, in alloxan-diabetic dogs, hypophysectomy can fully normalize postabsorptive glycemia, due to suppression of glucose production. Normoglycemia is, however, associated with an abnormally low glucose turnover. Hyperglucagonemia is important but not the sole factor responsible for diabetic overproduction of glucose. Hypophysectomy does not abolish the hepatic sensitivity to glucagon in insulin-deficient dogs. Persistence of hyperglycemia in some dogs after hypophysectomy is associated with less effective suppression of glucose production and with a very low glucose clearance.
Diabetes Mellitus in Hopi and Navajo Indians: Prevalence of Microvascular Complications
Authors: Rate Robert G , Knowler William C , Morse Harold G , Bonnell Mark D , McVey Jan , Chervenak Carol L , Smith Mike G , Pavanich Gary
Published: September 2013

In a cross-sectional study of Hopi and Navajo Indians with non-insulin-dependent diabetes mellitus, we found vascular complications to be strongly related to the duration of diabetes. In patients with diabetes of at least 10 yr duration, retinopathy was found in 57%, nephropathy in 40%, peripheral neuropathy in 21%, and peripheral vascular disease in 28%. For the Hopi and Navajo, the duration-specific prevalence rates of microvascular disease were very similar to prevalence rates found in many other populations. Thus we question the concept, based on reports in the late 1960s, that the Hopi and Navajo Indians have hyperglycemia as an isolated chemical abnormality unaccompanied by other manifestations of diabetes mellitus.
Impairment of Insulin-mediated Glucose Metabolism by Hyperosmolality in Man
Authors: Bratusch-Marrain Paul R , DeFronzo Ralph A
Published: September 2013

The deterioration of glucose tolerance and insulin resistance observed in states of hypertonie dehydration are commonly ascribed to a concomitant increase in circulating insulin counterregulatory hormones. To examine the effect of hyperosmolality per se on carbohydrate metabolism, tissue sensitivity to insulin was assessed by means of the euglycemic insulin clamp technique and simultaneous 3H-3-glucose kinetic analysis. Eight healthy volunteers participated in three protocols: (1) In the hyperosmolal study, serum osmolality was raised from 280 ± 1 to 302 ± 1 mosm/kg by a primed continuous infusion of hypertonie mannitol. Following 2 h of hypertonicity, a euglycemic insulin clamp study was performed. The plasma insulin concentration was acutely raised and maintained at 147 ± 20 μU/ml, while plasma glucose was maintained at basal levels; (2) In the control insulin clamp study, isotonic sodium chloride was infused instead of mannitol. No significant change in serum osmolality was observed during the control study; (3) To examine the effect of mannitol per se on insulin-mediated glucose metabolism, isotonic mannitol was infused in a third study to raise the plasma mannitol level to a similar extent as observed during the infusion of hypertonie mannitol. The serum tonicity did not change during the isotonic mannitol infusion.

Insulin-mediated glucose utilization (M) was 6.69 ± 0.51 mg/kg · min in the control study and decreased to 5.84 ± 0.40 mg/kg · min following the exposure to hyperosmolality (P < 0.05). When glucose uptake by the body was expressed per unit of plasma insulin (M/l ratio), the decrement in insulin-mediated glucose metabolism by hyperosmolality was 22% (5.56 ± 0.60 versus 4.30 ± 0.43 mg/kg · min per μM/ml × 100). This could not be accounted for by changes in the plasma levels of cortisol, growth hormone, or catecholamines. Basal hepatic glucose production (1.85 ± 0.08 mg/kg · min) as well as the degree of its suppression following hyperinsulinemia (95 ± 3%) were unchanged during hyperosmolality (1.84 ± 0.08 mg/kg · min and 94 ± 2%, respectively). The infusion of isotonic mannitol had no effect on insulin-mediated glucose metabolism or suppression of hepatic glucose production by insulin.

We conclude that moderate elevations in serum osmolality, less than 10%, cause a significant decrease in insulin-mediated glucose metabolism. Thus, hyperosmolality observed following severe dehydration should be regarded as an additional factor contributing to the development of insulin resistance. This pathophysiologic concept may be of particular relevance to diabetics with severe derangements of metabolic control. Our findings underline the importance of proper rehydration in restoring to normal insulin's action on intermediary metabolism in patients who present with hyperosmolality.
Skeletal Muscle in Alloxan Diabetes: A Comparison of Isometric Contractions in Fast and Slow Muscle
Authors: Paulus Stephen F , Grossie J
Published: September 2013

Diabetes was produced by withholding insulin treatment from previously alloxanized female rats. Isometric contraction was assessed in soleus and extensor digitorum longus (EDL) muscles removed 2 h to 32 days after insulin withdrawal. Directly induced contractions were measured in vitro at 20°C. In soleus muscles from severely diabetic rats, average twitch and tetanic forces were normal or slightly greater than that of controls of similar age, whereas in EDL, marked decreases appeared in both twitch and tetanic forces. Soleus muscle from severely diabetic rats was not depolarized as already reported in EDL. After 16 and 32 days in the diabetic state, soleus muscles from moderately diabetic rats generated average tetanic forces that were equal to that found in age-matched controls, whereas EDL tetanic forces were significantly (P = <0.01) weaker. Average specific twitch force in diabetic soleus muscles was greater than age-matched controls after 16 and 32 days in the diabetic state. In diabetic soleus muscle, significant increases in the average half relaxation time and twitch duration were seen after prolonged (16 and 32 days) periods of diabetes. No changes were seen in the same temporal parameters of the twitch in diabetic EDL muscle. A greater atrophy appeared in EDL than in soleus after 16 and 32 days of uncontrolled diabetes.
Effect of Glucose Stimulation on 45Calcium Uptake and Total Calcium Content of Pancreatic Islets of Fed and Fasted Rats and Obese Hyperglycemic Mice
Authors: Wolters G H , Wiegman J B , Konijnendijk W
Published: September 2013

Effects of fasting on glucose-induced changes of various calcium parameters were investigated. The total calcium content of islets of fed rats and obese mice, determined by fluorometric microanalysis, amounted to 575 ± 25 and 600 ± 75 pmol/μg DNA, respectively. Fasting for 24 or 72 h had no effect on the calcium content of rat islets, but increased that of mice by 30%. Glucose stimulation did not alter their total calcium content. The amount of 45Ca (as percentage of total islet calcium content) taken up over 30 min by fed mouse islets at 2.5, 10, and 15 mM glucose was equivalent to 32%, 41%, and 44% and by fed rat islets to 25%, 31%, and 34%, respectively. The net uptake of fed rat islets over 60 min at 2.5 and 15 mM glucose amounted to 36% and 61%. Fasting for 24 h inhibited insulin secretion over 30 min but not 45Ca uptake, whereas both parameters were inhibited after fasting for 72 h. Insulin secretion of mouse islets, was inhibited after 24 and 72 h of fasting, but 45Ca uptake was not significantly affected. Since glucose stimulates 45Ca uptake without changing the total islet calcium content, it must represent 45Ca–40Ca exchange. Stimulation of insulin secretion of rat islets is associated with an increased calcium influx rate and increased exchangeable calcium pool(s) size. Calcium pool(s) size seems not to be altered by 24 h of fasting; however, 72 h of fasting tends to decrease the pool(s) size. The inhibition of insulin secretion induced by 24 h of fasting is not due to an altered calcium uptake, but it may be due to a modification of intracellular handling of calcium.
Impairment of T-Cell Regulation of the Humoral Immune Response to Type III Pneumococcal Polysaccharide in Diabetic Mice
Authors: Busby Barbara E , Rodman Harvey M
Published: September 2013

The peak plaque-forming-cell (PFC) and serum antibody responses of diabetic mice to type III pneumococcal capsular polysaccharide (S3) were delayed compared with normals. Proliferation of PFC precursors was not inhibited in an insulin-deficient environment. The delay in the PFC response to S3 did not occur in diabetic nude mice but was demonstrable in their thymus-bearing heterozygote littermates. Therefore, T-cells appear to mediate the delay in the response of diabetic mice to S3 probably by delaying their differentiation into PFC. Diabetic mice responded normally to the induction of low-dose tolerance to S3, indicating the presence of active suppressor T-cells (Ts) in these mice. However, inactivation of Ts by anti-lymphocyte serum (ALS) required a higher dose in the diabetic mice. Furthermore, inactivation of Ts by ALS totally abolished the delay in peak PFC response. These findings suggest that the delayed PFC response to S3 in diabetic mice was the result of excessive splenic Ts activity. In peripheral blood, diabetic mice appeared to have more amplifier T-cell activity or less suppressor T-cell activity than normals. This response was normalized by insulin treatment.
Effect of Exercise Training and Sucrose Feeding on Insulin-stimulated Glucose Uptake in Rats with Streptozotocin-induced Insulin-deficient Diabetes
Authors: Dall'aglio Elisabetta , Chang Fred , Chang Helen , Wright Diana , Reaven Gerald M
Published: September 2013

The effect of exercise training and a sucrose-rich diet on insulin-stimulated glucose disposal was studied in rats with streptozotocin-induced insulin deficiency. Rats were injected with streptozotocin (40 mg/kg), and 3 days later divided into three groups with equal degrees of hyperglycemia. One group of rats was allowed to run spontaneously on exercise wheels, another group remained sedentary but ate a sucrose-rich diet (66% sucrose), and the third also remained sedentary but consumed conventional rat chow. Three weeks later, we determined the effect of these various programs on postabsorptive plasma glucose and insulin levels, as well as on the ability of exogenous insulin to stimulate disposal of a glucose load during a period in which endogenous insulin was suppressed by epinephrine and propanolol. Basal plasma insulin levels were the same in all three groups, but plasma glucose levels were significantly lower (P < 0.001) in exercise-trained rats, and significantly higher (P < 0.05) in sucrose-fed rats, than in chow-fed diabetic rats. The inference that exercise training markedly enhanced insulin action in rats with insulin deficiency was borne out by direct estimation of insulin-stimulated glucose disposal. In contrast, sucrose-fed diabetic rats seemed to be more insulin-resistant than chow-fed diabetic rats. These results provide direct evidence that spontaneous exercise can dramatically attenuate the severity of diabetes in insulin-deficient rats by enhancing insulin action.
Fibrinolytic Activity, Autonomic Neuropathy, and Circulation in Diabetes Mellitus
Authors: Almér Lars-Olof , Sundkvist Göran , Lilja Bo
Published: September 2013

In diabetes mellitus the vascular endothelium often produces and releases abnormally low amounts of plasminogen activator, leading to an impaired fibrinolytic system, which might be of importance for the development of angiopathy.

In this study tests of autonomic neuropathy (AN) were performed on diabetics without autonomic symptoms. It was discovered that diabetics without AN had a significantly lower mean fibrinolytic response to stimulation than nondiabetic controls, whereas this reduction was not found in those with AN. The suggestion that asymptomatic AN might induce a normalization of the impaired fibrinolytic system in diabetes, and thus have a modifying effect on the rate of development of angiopathy, requires further study to be properly evaluated.
Somatomedin Inhibitors in Serum and Liver of Growth Hormone-Deficient Diabetic Rats
Authors: Vassilopoulou-Sellin Rena , Oyedeji Caroline O , Samaan Naguib A
Published: September 2013

Diabetes of moderate severity was induced with streptozotocin in growth hormone (and therefore somatomedin)-deficient rats. Somatomedin inhibitors were identified in the serum and liver perfusate of these animals, as shown by the ability of samples to blunt basal cartilage sulfation and cartilage stimulation by added normal serum. The data suggest that the induction of somatomedin inhibitors is under the influence of insulin and nutrition rather than growth hormone, indicating that their regulation may differ from that of growthpromoting somatomedins. With this model, it is possible to obtain preparations that are relatively free of somatomedins in which to study the properties of somatomedin inhibitors.
Binding of Insulin by Monkey and Pig Hypothalamus
Authors: Landau Bernard R , Takaoka Yoshiro , Abrams Marc A , Genuth Saul M , van Houten Mark , Posner Barry I , White Robert J , Ohgaku Seiji , Horvat Agnes , Hemmelgarn Edward
Published: September 2013

Membrane preparations from monkey and pig hypothalami bound [125]insulin specifically. The binding appeared to be greater by preparations from anterior than posterior portions of the pig hypothalamus. Binding was time dependent, and its dissociation was first order with a half-time at 22°C of 14 min. Desalanine insulin was as effective as native insulin in inhibiting the binding of [125I]insulin, while proinsulin was less effective and desoctapeptide insulin still less effective in accord with their biologic activities. Binding by membranes from cortex and thalamus appeared to be less than from hypothalamus.

[125I]lnsulin was infused into an arterial split monkey brain preparation to determine if insulin that was blood borne bound specifically to the primate hypothalamus. Half the brain was perfused with [125I]insulin alone and the other half with [125I]insulin plus an excess of unlabeled insulin. Radioautography showed specific binding of insulin localized to the median eminence, infundibular nucleus, and microvessels.

Thus, the monkey and pig hypothalami bind insulin with characteristics similar to those reported for known target tissues for insulin. Furthermore, insulin from the blood stream binds to specific anatomical structures in the hypothalamus of the monkey.
Spontaneous Diabetes Mellitus in the BB/W Rat: Effects of Glucocorticoids, Cyclosporin-A, and Antiserum to Rat Lymphocytes
Authors: Like A A , Anthony M , Guberski D L , Rossini A A
Published: September 2013

Combination immunosuppression therapy with long-acting glucocorticoids, cyclosporin-A, and antiserum to rat lymphocytes (ALS) reduced the severity of spontaneous diabetes among BioBreeding/Worcester rats and decreased the frequency of diabetes in susceptible littermates. Combination therapy with glucocorticoids and three injections of ALS reversed hyperglycemia in a significant number of acutely diabetic animals. These results strengthen the hypothesis that autoimmunity plays a role in the pathogenesis of diabetes in these animals and increase our understanding of the requirements of treatment protocols for the prevention and cure of this spontaneous syndrome.
Fetal and Neonatal Metabolism in the Pup of a Canine Diabetic Mother: Fasting Circulating Fuels and Neonatal Glucose Turnover
Authors: Kliegman R M , Miettinen E L , Tserng K Y
Published: September 2013

The metabolic effects of previously induced alloxan diabetes were investigated among fasted newborn dogs during the first day of life. Maternal insulin-dependent diabetes resulted in enhanced maternal and fetal blood glucose and ketone bodies, while postnatal levels of these substrates were not altered. Plasma insulin levels were augmented in the fetus and neonate (3 and 6 h of age) of the diabetic mother, while pancreatic insulin content was also enhanced at fetal and 3 h of age. Circulating free fatty acid levels were diminished among pups born to diabetic mothers (IDM pups) at 3 and 6 h of age, while glycerol levels were unaffected. Nevertheless, plasma triglyceride concentrations were elevated in pups of diabetic mothers during fetal and at 3 and 6 h of newborn fasting. Systemic glucose turnover was not altered in pups of diabetic mothers at 3, 9, or 24 h, while at 6 h, glucose turnover appeared enhanced in IDM pups, which was due in part to a decline of glucose production between 3 and 6 h among controls. Gluconeogenesis was attenuated at 9 h of age among IDM pups, but increased by 24 h of age.

Hyperinsulinism in the presence of unaltered glucose turnover with attenuated free fatty acid levels suggest that neonatal canine glucose production from hepatic glycogen is less sensitive to insulin's effect than is the lipolysis-lipid reesterification cycle. Gluconeogenesis from lactate may be unnecessary if glycogenolysis is able to support systemic and hepatic substrate requirements, while insulin mediated lipid synthesis may augment tissue triglyceride deposits.
Fetal and Neonatal Metabolism in the Pup of a Canine Diabetic Mother: Hepatic Intermediary Metabolism
Authors: Kliegman R M , Miettinen E L
Published: September 2013

The intrahepatic metabolic profile of pups from a diabetic canine pregnancy (IDM pups) was examined at birth and during the postnatal adaptation to 3, 6, 9 or 24 h of neonatal fasting. Hepatic intermediates of the glycogen, glycolytic, and Krebs cycles were determined in addition to hepatic adenine nucleotides and hepatic and muscle triglyceride concentrations. Maternal canine diabetes enhanced fetal hepatic and muscle glycogen and triglyceride content. After birth, neonatal hepatic glycogen content declined among control and IDM pups but glycogen content remained enhanced in the IDM pups at 3 and 6 h. Muscle glycogen also declined in both groups; however, it remained higher in the IDM at 3, 6, and 9 h. Muscle and hepatic triglyceride content increased in both groups. Postnatal intracellular triglyceride content was augmented in muscle tissue of the IDM at 3, 6, and 9 h while hepatic tissue from IDM had increased triglycerides at 24 h of age. Glycolytic intermediates demonstrated alterations following maternal diabetes as fructose 1, 6, diphosphate was lower in IDM pups during fetal life and at 3, 9, and 24 h while pyruvate and oxaloacetate concentrations were augmented throughout the study period when compared with age-matched controls.

Hepatic amino acids demonstrated elevated alanine concentrations in IDM pup at 6, 9, and 24 h while aspartate levels were augmented during fetal and at 6, 9, and 24 h of neonatal fasting.

These data suggest that hepatic glycogen synthesis is augmented in the fetus of the diabetic canine mother. After birth postnatal glycogenolysis is not altered and may support hepatic and systemic oxidative metabolism. Furthermore, these large tissue stores of glucose may contribute to hepatic or muscle triglyceride synthesis in addition to hepatic amino acid accumulation. The alterations of FDP, pyruvate, and oxaloacetic acid suggests that glycolysis is enhanced among pups following a diabetic pregnancy while intraheptic gluconeogenesis may be attenuated.
Role of Glucagon in Enhancing Ketone Body Production in Ketotic Diabetic Man
Authors: Keller U , Schnell H , Sonnenberg G E , Gerber P P G , Stauffacher W
Published: September 2013

To assess the role of endogenous glucagon in regulating hepatic ketone body production in ketotic insulinwithdrawn diabetic subjects, ketone body kinetics were determined in two groups of C-peptide-negative diabetics 6 h after interruption of a s.c. insulin infusion. In group 1 (N = 5), glucagon levels were suppressed by infusion of somatostatin (SRIF), whereas in group 2 (N = 6) glucagon was replaced during SRIF by infusing glucagon at 2 ng/kg/min. Ketone body production rates as determined by primed-continuous infusion of [3-14C]acetoacetate declined from 19.5 ± 0.8 to 16.4 ± 0.4 fimol/kg/min (P < 0.01) during 105 min of SRIF-induced glucagon suppression, whereas they remained unchanged (+ 0.2 ± 0.4 μmol/kg/min, P < 0.01 compared with SRIF) during glucagon replacement. Total ketone body concentrations remained unchanged during SRIF infusion but increased from 2.2 ± 0.3 to 2.9 ± 0.2 mmol/L (P < 0.01) during glucagon replacement. The metabolic clearance rate of total ketone bodies declined significantly (P < 0.01) by 27% and 21% in the two groups. Plasma free fatty acid and glycerol concentrations remained unchanged in both groups whereas plasma glucose decreased by 3.2 ± 0.5 mmol/L during SRIF (P < 0.01). Thus, endogenous glucagon contributed significantly to the maintenance of ketone body production rates in ketotic insulin-deficient diabetics. Since ketogenesis was altered in the absence of changes in free fatty acid levels, the results suggested that glucagon enhanced ketogenesis by an intrahepatic effect.
Chloride Modulation of Insulin Release, 86Rb+ Efflux, and 45Ca2+ Fluxes in Rat Islets Stimulated by Various Secretagogues
Authors: Tamagawa Tatsuo , Henquin Jean-Claude
Published: September 2013

Substitution of extracellular CI− by impermeant isethionate (5 mM residual CI−) caused a monophasic inhibition of glucose-stimulated insulin release, accompanied by an initial transient increase and a secondary lasting decrease in 86Rb+ efflux from perifused islets. CI− reintroduction restored insulin release with an overshoot above control values and successively produced a small decrease and a large increase in efflux. Theophylline potentiated the insulinotropic effect of glucose more markedly at low CI− than at normal CI−, but did not restore a normal rate of 86Rb+ efflux. Lowering the concentration of CI− did not alter the effect of glucose, tolbutamide, or arginine on 86Rb+ efflux, but simply shifted the efflux rates to lower values. The first phase of glucose-stimulated insulin release was not modified, but the second phase was inhibited. The insulinotropic effect of tolbutamide was augmented at low CI− and that of arginine (at 7 mM glucose) was not affected. In incubated islets, the stimulation of insulin release by glyceraldehyde was barely inhibited when CI− was substituted by isethionate and the marked decrease of the effect of glucose could be prevented by glutamine. In a glucose-free, low CI− medium, the insulinotropic effect of leucine, arginine, and lysine was inhibited; this inhibition was reversed by glutamine, but not by theophylline. Lowering the concentration of CI− had no effect on 45Ca2+ influx or efflux in the absence of glucose, did not alter the increase in influx and efflux during the first 5 min of glucose stimulation, but impaired both influx and efflux during the second phase. Leucine-induced 45Ca2+ uptake was inhibited at low CI− and this inhibition was prevented by glutamine. In conclusion, islet cells possess a CI−-activated modality of K efflux, which does not seem to play a role in the stimulus-secretion coupling. Since CI− substitution by an impermeant anion does not inhibit the stimulation of insulin release by all agents, the role of CI− ions does not appear to be restricted to a chemiosmotic mechanism of exocytosis. No single mechanism explains the multiple changes in B-cell function resulting from the decrease in CI− concentration, but it is proposed that some of them could result from modifications of intracellular pH.
Abnormalities of GIP in Spontaneous Syndromes of Obesity and Diabetes in Mice
Authors: Flatt Peter R , Bailey Clifford J , Kwasowski Peter , Swanston-Flatt Sara K , Marks Vincent
Published: September 2013

The role of GIP in the pathogenesis of spontaneous syndromes of obesity-diabetes wasexamined in ob/ob mice of the Aston stock and db/db mice of the C57BL/KsJ background. Compared with lean controls, fed adult ob/ob and db/db mice, respectively, exhibited 1.8- fold and 2.1-fold increases in body weight, 1.8-fold and 2.8-fold elevations of plasma glucose, and 15.4-fold and 5.6-fold elevations of plasma insulin. As indicatedby the relative magnitude of the hyperglycemia and hyperinsulinemia, db/db mice displayed a particularly severe form of diabetes. Plasma GIP concentrations of ob/ob and db/db mice were elevated 15.1-fold and 6.2- fold, respectively; the increments closely corresponded with the degrees of hyperinsulinemia. Small intestinal weight was increased 1.4-fold and 1.8-fold in ob/ob and db/db mice, respectively, but the intestinal GIP content expressed as μg/g intestine or μg/intestine was raised only in ob/ob mice (1.9-fold and 2.8- fold, respectively). Since glucose stimulation of insulin release is defective in both mutant strains, the results strongly implicate pathologically raised GIP concentrations in the hyperinsulinemia and related metabolic abnormalities of the obesity-diabetes syndromes. It is suggested that hypersecretion of GIP results in part from loss of normal feedback inhibition by endogenous insulin.