bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Therapy on the Nature and Quantity of Fuels Oxidized During Diabetic Ketoacidosis
Authors: Owen O E , Trapp V E , Reichard G A , Mozzoli M A , Smith R , Boden G
Published: September 2013

We studied seven patients, in moderate to severe diabetic ketoacidosis (DKA), measuring respiratory exchanges of O2, GO2, and acetone and urinary excretion of nitrogen, ketone bodies, and glucose to calculate the respiratory quotient (RQ), nonprotein respiratory quotient (npRQ), metabolic requirements, and calories derived from fat, carbohydrate, and protein oxidation. Results from indirect calorimetry were related to circulating concentrations of glucose, free fatty acids, ketone bodies, and amino acids over a 14-h study consisting of a 2-h period I of rehydration with saline, a 4-h period II of rehydration and insulin therapy, and an 8-h period III of rehydration, insulin, and glucose administration.

During period I, of about 2 h of saline rehydration, the RQ (0.55–0.80) and npRQ (0.58–0.88) varied among the patients but in general was low. The caloric requirements were 1.24 kcal/min/1.73 m2. Initially,fat contributed 78 ± 11%, glucose 17 ± 10%, and protein 5 ± 2% of the metabolic requirements. The circulating concentrations of fuels remained constant. During period II, after about 4 h of saline and insulin therapy, the RQ (0.62–0.88) and npRQ (0.55–0.91) remained rather stable, rising in only two of seven patients. Nevertheless, in all patients, saline and insulin therapy was associated with precipitous decreases in circulating concentrations of glucose, free fatty acids, acetoacetate, and beta-hydroxybutyrate and gradual decreases in plasma amino acids. During period III, after 8–12 h of insulin therapy, the RQ (0.68–0.92) and npRQ (0.48–1.01) increased, rising in five of six patients. Heightened RQ and npRQ values were observed only after plasma free fatty acid concentrations decreased to 0.44 ± 0.12 mM and plasma acetoacetate plus beta-hydroxybutyrate concentrations decreased to 5.27 ± 1.86 mM, while plasma glucose concentration remained elevated at 13.49 ± 3.67 mM because of intravenous glucose infusion.

Caloric requirements diminished progressively throughout the study, and after about 4 h of saline and insulin therapy a reciprocal relationship between the contributions of fat and glucose to metabolic requirements was evident. At the end of period III the caloric requirements were 0.77 kcal/min/1.73 m2. Fat contributed 44 ± 16%, glucose 42 ± 22%, and protein 14 ± 8% of the metabolic requirements.

We have observed a dissociation between the decrease in plasma glucose, free fatty acids, ketone bodies, and amino acids and the nature of fuels oxidized. This suggests that, during the initial hours of therapy for DKA, the predominant effect of insulin is to promote fuel storage rather than to promote glucose and ketone body oxidation. It was 8–12 h in the course of therapy before the npRQ rose, reflecting heightened glucose oxidation and diminished fat oxidation. Metabolic requirements progressively decreased with therapy.
Increased Glycosylation of Serum Albumin in Diabetes Mellitus
Authors: Dolhofer R , Wieland O H
Published: September 2013

The level of glycosylated albumin has been determined in the serum of normal and diabetic subjects after purification of the albumin to apparent homogeneity. The sugar was released from the albumin preparations as 5-hydroxymethylfurfural (HMF) after 24 h of hydrolysis in 2 N acetic acid at 92°C, and it was assayed by the thiobarbituric acid reaction. The mean value for glycosylated albumin, expressed as picomoles of HMF per nanomole of albumin, obtained from 10 normal control and 65 diabetic subjects, was 64 and 124, respectively. The level of glycosylated albumin correlates with the mean blood glucose concentration (N = 55, r = 0.715), but not with the fasting blood sugar concentrations. Moreover, a linear relationship was observed between the amounts of glycosylated hemoglobin (HbAla−c) and glycosyl-albumin (n = 74, r = 0.88). In an insulin-treated diabetic patient, there was a different temporal relationship between blood glucose concentrations and glycosylated hemoglobin and albumin levels. While HbAla−c was lowered by only 15% after 20 days, glycosylated albumin had dropped by more than 50% during the same time. Our results indicate that glycosylated albumin might provide a valuable tool to assess the average blood sugar levels between shorter intervals, since the turnover of serum albumin is considerably faster than that of HbAla−c.
L-Asparaginase-induced Diabetes Mellitus in Rabbits
Authors: Lavine Robert L , Dicintio Deborah M
Published: September 2013

Twenty-seven male New Zealand White rabbits were injected with a single dose of 10,000 IU E. coli L-asparaginase per kilogram body wt to document the diabetogenic activity of this antitumor agent. Significant weight loss was observed by day 1, and á loss continued until day 9. After day 16, weight steadily increased.

Random serum glucose levels increased steadily after the injection of L-asparaginase, reaching a peak value of 344 ± 32 mg/di ( ± SEM) on day 10. From day 12, levels declined, but they remained significantly higher than basal levels. Serum immunoreactive insulin (IRI) levels had a similar pattern of response. By day 2 the IRI was significantly above baseline. The IRI levels increased daily, reaching a peak level of 1379 ± 587 pg/ml ( ± SEM). Thereafter the levels fell gradually. However, the IRI levels remained significantly.higher than basal levels. Intravenous regular insulin decreased glucose levels in L-asparaginase–treated animals at 3 h by only 7.7 ± 3.2%, while it decreased them in controls by 34.0 ± 6.7% (P < 0.0025).

These data demonstrate that, acutely, a single intravenous dose of 10,000 IU E. coli L-asparaginase per kilogram body wt induces a hyperinsulinemic, insulin-resistant, diabetic syndrome in rabbits.
Inherited, Early Onset, Insulin-requiring Diabetes Mellitus of Keeshond Dogs
Authors: Kramer John W , Nottingham S , Robinette J , Lenz G , Sylvester S , Dessouky M I
Published: September 2013

Spontaneous diabetes mellitus has been characterized in a line of nonobese purebred keeshond dogs as an insulin-requiring hereditary disorder with onset at between 2 and 6 mo of age. Diabetic dogs developed cataracts, became ketotic, hyperglycemie, hypercho-lesterolemic, lipemic, and hypoinsulinemic. Basal glucagon, cortisol, and T4 serum concentrations and responses to ACTH, TSH, and arginine were normal. Light microscopic studies of the pancreas by immunocytochemical procedures revealed the absence of islet B cells, the presence of A cells, and solitary B cells. Diabetic dogs had poor fecundity, and a single puberal diabetic male had poor semen quality and was unable to sire pups. Parents of diabetics and nondiabetic siblings were normal. This spontaneous form of diabetes mellitus, with similar lesions to the insulin-dependent diabetes of people, will be a valuable aid to comparative biomedicai research of diabetes mellitus.
Characterization of the Conversion of a Somatostatin Precursor to Somatostatin by Islet Secretory Granules
Authors: Fletcher Donald J , Noe Bryan D , Eric Bauer G , Quigley James P
Published: September 2013

The existence of a biosynthetic precursor for somatostatin has been previously demonstrated in angler-fish pancreatic islet tissue. In the present study, the subcellular conversion of this precursor to somatostatin was examined. When subcellular fractions were assayed for immunoreactive somatostatin, 86% of the immunoreactivity was found in the microsome and secretory granule fractions. Based on this finding and results from previous studies on proglucagon and proinsulin conversion, only these two fractions were examined for converting activity. After incubating islet tissue with [3H]tryptophan and [35S]cystine or [14C]iso-leucine for varying time periods, the tissue was fractionated and the microsome and granule fractions were subjected to postincubation. Conversion was monitored by the calculation of percent accumulation of somatostatin in eluates after Bio-Gel P-10 filtration of fraction extracts. Both secretory granules and microsomes converted endogenously labeled 8000–15,000-dalton precursor peptides to somatostatin. Disruption of the granules by repeated freeze-thawing or osmotic shock did not affect converting activity. Conversion of exogenously labeled precursors was also observed in both fractions. When granules were subjected to repeated freeze-thawing and high-speed centrifugation to separate membranes from sol, the membranes were found to have 29% more converting activity than the resulting supernates. Both membranous and soluble converting activities were significantly inhibited in the presence of leupeptin but not phenylmethyl sulfonyl fluoride. Significant inhibition of conversion was observed when lysed granules were postincubated in the presence of antipain, leupeptin, and p-chloromercuribenzoate but not chloroquine, di-isopropyl fluorophosphate, EDTA, or N-p-tosyl-L-lysine-chloromethyl ketone HCI. These results indicate that the prosomatostatin converting enzyme is a unique membrane-associated thiol proteinase with a possible specificity for arginine residues. The findings also indicate that the intracellular transport and processing of prosomatostatin is similar to that of other peptide hormone precursors.
Failure to Demonstrate Increased Protein Turnover and Intracellular Proteinase Activity in Livers of Mice with Streptozotocin-induced Diabetes
Authors: Bond Judith S
Published: September 2013

The effect of streptozotocin-induced diabetes on the turnover of acidic and basic mouse liver cytosol proteins was assessed. Previous work by others had demonstrated that acidic proteins are degraded more rapidly than basic proteins in livers of normal but not in severely diabetic animals. In this study, a milder form of diabetes was investigated to determine whether insulin-dependent diabetes in the absence of starvation, large weight losses, and impending death results in fundamental changes in degradation of the normally labile (acidic) proteins and stable (basic) proteins. The relative rates of degradation of liver proteins were measured by a double-isotope technique and by the loss of protein radiolabeled with [14C]-bi-carbonate. The relative rates of synthesis of proteins were estimated by incorporations of [3H]-leucine. No fundamental change in the relative rates of synthesis or degradation of acidic and basic proteins was observed. There was a general decrease in the incorporation of radiolabeled amino acids in the diabetic state and an increase in the specific activity of some amino acid–metabolizing enzymes, indicating changes in amino acid metabolism in liver. A study of the quantity and subcellular distribution of several liver cell proteinases revealed little if any changes in the proteolytic machinery of liver cells in this form of insulin-dependent diabetes. Thus, the fundamental changes in protein degradation seen in severe diabetes are not observed in a less severe form of the disease.
Binding and Degradation of Semisynthetic Tritiated Insulin by IM-9 Cultured Human Lymphocytes
Authors: Misbin Robert I , Davies J Gwyn , Offord Robin E , Halban Philippe A , Mehl Thomas D
Published: September 2013

Insulin was tritiated by semisynthetic replacement of the amino-terminal phenylalanine of the B chain with tritiated phenylalanine. At 15°C, (3H) insulin bound to high affinity receptors on IM-9 cultured human lymphocytes with an affinity constant of about 3 × 109 M−1. The Scatchard plot was curvilinear. At 37C, maximal binding occurred after about 15 min of incubation. Binding fell thereafter due to degradation of insulin by the extracellular fluid. The major degradation product after 120 min coeluted with insulin from Sephadex G-50 and was precipitated by anti-insulin antibody but to a lesser degree than intact insulin. It had little or no biologic activity as assessed by binding to IM-9 lymphocytes. The cell-associated radioactivity was also eluted as a single peak on Sephadex G-50. In contrast to the degradation product, this material retained its ability to bind to insulin receptors. We deduce that this cell-associated material contains the entire A chain, most of the B chain, and is probably native insulin. These data show that insulin bound to IM-9 lymphocytes remains biologically intact.
The Insulin Response to Intravenous Fructose in Maturity-onset Diabetes Mellitus and in Normal Subjects
Authors: Lawrence James R , Gray Christine E , Grant Ian S , Ford James A , McIntosh William B , Dunnigan Matthew G
Published: September 2013

Insulin responses to intravenous fructose and glucose were measured in 15 patients with maturity-onset diabetes mellitus. In eight patients given fructose first the insulin responses to fructose and glucose were similar. In seven patients given glucose first the insulin response to subsequently infused fructose was significantly greater than to glucose. Multiple regression analysis showed that the ratio of the fructose to glucose insulin response, assessed by area under the insulin serum concentration-time curve (F/G ratio) in individual patients, correlated most closely with prefructose infusion plasma glucose. Similar analysis, applied to results in 27 normal subjects, showed that the most important determinant of the insulin response to fructose in this group also was the immediate prefructose infusion plasma glucose. Thus in diabetics, as in normal controls, the response of the beta cell to intravenous fructose appears to be sensitively set by the ambient plasma glucose concentration at the onset of fructose infusion.
Induction in C57BL/KsJ Mice of Complement-dependent Antibody Cytotoxic to Cultured Beta Cells
Authors: Leiter Edward H , Simon Douglas , Cherry Marianna , Phillips Catherine A
Published: September 2013

Despite widespread evidence that autoimmune mechanisms may contribute to the beta cell necrosis associated with type I insulin-dependent diabetes mellitus (IDDM), it has not heretofore been demonstrated that islet cell antibodies (ICAs), directed primarily against cytoplasmic antigens, are capable of specific lysis of beta cells. We utilized a readily accessible source of mouse pancreatic islets [CBA/J mice lacking exocrine pancreas (exocrine pancreatic insufficiency syndrome)] to experimentally induce ICAs in inbred mice. Homogenates of these islets were injected weekly for four weeks into syngeneic (CBA/J) and allogeneic (A/J, C57BL/6J, C57BL/KSJ) recipients. Only C57BL/KsJ inbred mice showed the induction of a high titer (≥160) antiserum cytotoxic to 51Cr-labeled CBA/J lymph node target cells. Neither the immunized C57BL/KsJ mice with circulating ICAs nor any of the other immunized strains showed any decrease in glucose tolerance as compared with vehicle controls. Moreover, no morphologic evidence of islet necrosis or atrophy was apparent. Thus the ICAs induced were reactive with alloantigenic determinants of the donor and unreactive with antigenic determinants of the recipient strain. The C57BL/KsJ antiserum was further screened for anti-islet cell cytotoxic activity using both a 51Cr release assay from CBA/J islet cell monolayer cultures, and immunocytochemical staining of sections of Bouin's fixed, paraffin-embedded pancreas. This antiserum was cytotoxic to CBA/J beta cells in monolayer culture, but not the other non-beta islet cell types. Immune lysis of the beta cells required rabbit complement. At a concentration of 1% antiserum and 4% complement, beta cell lysis was evident between 3 and 4 h at 37°C. Ultrastructural examination of beta cells exhibiting cytopathic changes revealed cytoplasmic disarray rather than any obvious lytic events at the plasma membrane. Grossly distended, rough, endoplasmic reticulum containing intra-cisternal type A retrovirus was the most prominent feature distinguishing antiserum and control serum-treated beta cells. This model system suggests that ICAs which recognize beta cell cytoplasmic antigens are capable of specifically lysing beta cells via a complement-dependent mechanism. Immunocytochemical staining revealed that, in addition to islet beta cells, the antiserum (1/500 dilution) stained a macrophage-like cell in spleen and lymph nodes, as well as an epithelial-like cell in the thymus. The possibility is discussed that this multiple specificity may have been due to passenger leukocytes present in the islet homogenates used to immunize.
Glucose and Cyclic AMP as Stimulators of Somatostatin and Insulin Secretion From the Isolated, Perfused Rat Pancreas: A Quantitative Study
Authors: Gerber Pietro P G , Trimble Elisabeth R , Wollheim Claes B , Renold Albert E , Miller Ralph E
Published: September 2013

The secretory responses of beta and delta cells were compared in the isolated, perfused, rat pancreas. Insulin release was stimulated 50-fold and somatostatin (SRIF) secretion twofold when the glucose concentration was increased from 100 mg/dl to 300 mg/dl. When islet cyclic AMP (cAMP) was raised by 3-isobutyl-1-methylxanthine (IBMX), the secretion of SRIF was stimulated in a glucose-dependent manner (300 mg/dl > 100 mg/dl > 25 mg/dl). As expected, insulin release was also potentiated in a similar fashion. A difference in the glucose dependency of the cAMP effect was seen at 25 mg/dl glucose, where 0.25 mM IBMX enhanced the release of SRIF but not that of insulin. In contrast, at 300 mg/dl glucose, IBMX caused a greater potentiation of insulin release than of SRIF release. The release of insulin, when expressed in absolute terms, was stimulated more markedly than that of SRIF under most conditions tested. However, the expression of total hormone released during 30 min of stimulation as a percentage of tissue hormone content allowed a different interpretation of the results. For example, 2.1% and 1.8% of tissue insulin and SRIF contents, respectively, was released during exposure to 300 mg/dl glucose. Surprisingly, under basal conditions (100 mg/dl glucose), 1.0% of total SRIF content was released during 30 min compared with the release Of only 0.04% of insulin.
Insulin in Insects and Annelids
Authors: LeRoith Derek , Lesniak Maxine A , Roth Jesse
Published: September 2013

The fruitfly, Drosophila melanogaster, and the earthworm, Annelida oligocheta, were extracted with acid-ethanol by a classic method for recovering insulin from the pancreas. When each extract was filtered on a Sephadex G-50 column, a distinct peak of insulin immunoreactivity (equivalent to 0.1 to 2 ng of insulin/g wet weight) was recovered in the region typical of insulin. The material in this peak had reactivity in the insulin bioassay, measuring stimulation of glucose oxidation or lipogenesis by isolated rat adipocytes. The bioactivity was partially or largely neutralized by anti-insulin antibodies. In concordance with previous work showing the presence of material very similar to insulin in the blowfly and molluscs, we have confirmed the presence of insulin in insects and extended the observation to earthworms. These findings suggest that insulin is more widespread in invertebrates than was previously thought. In a companion study (Proc. Nati. Acad. Sci. USA 77:6184-88, 1980), we have demonstrated material similar to insulin in unicellular organisms.
Retrograde Axonal Transport of Transmitter Enzymes, Fucose-Labeled Protein, and Nerve Growth Factor in Streptozotocin-Diabetic Rats
Authors: Jakobsen Johannes , Brimijoin Stephen , Skau Kenneth , Sidenius Per , Wells David
Published: September 2013

Rapid axonal transport was studied by several methods in rats with serum glucose levels above 300 mg/dl as a result of treatment with streptozotocin (45–50 mg/kg) 3 days, 1 wk, 4 wk, 8 wk, or 4 mo earlier. With untreated age-matched rats as controls, rapid anterograde axonal transport in the sciatic nerves of diabetic rats appeared entirely normal. Statistically significant differences were never observed between experimental and control nerves in the basal content of acetylcholinesterase (AChE) and dopamine-β-hydroxylase (DBH) activity or in the rate of accumulation of these enzymes proximal or distal to a ligature. Therefore, the basic capacity for rapid anterograde and retrograde axonal transport of proteins was probably unimpaired in the diabetic nerves. The accumulation of labeled glycoproteins proximal to ligatures on the contralateral nerves of the same rats after injection of the L5 dorsal root ganglion with 3H-fucose was likewise normal. However, rats with 1, 4, and 8 wk of diabetes did show reduced accumulation of fucose-labeled protein distal to nerve ligations, indicating a long-lasting abnormality of retrograde axonal transport. Furthermore, this abnormality was reversed by daily insulin treatment during the second half of an 8-wk experimental period. It is therefore unlikely that the depression of retrograde transport reflects direct toxic effects of streptozotocin. We conclude that streptozotocin-induced diabetes leads to: (1) abnormal delay in the turnaround of transported proteins in distal nerve regions, perhaps combined with (2) an abnormal metabolism of glycoproteins. A delayed onset of retrograde transport is consistent with present observations of reduced accumulation of 125I-labeled nerve growth factor (NGF) below a midthigh ligature on the sciatic nerve after injection of this protein into the hindfoot of rats with 3–5 wk of diabetes. Further work on the factors controlling rapid retrograde transport of proteins in diabetic nerve is warranted.
Increased Concentration of Albumin in Kidney Basement Membranes in Diabetes Mellitus
Authors: Michael Alfred F , Brown David M
Published: September 2013

The concentration of albumin was measured by a double-antibody radioimmunoassay in the glomerular basement membrane (GBM) and tubular basement membrane (TBM) of patients with diabetic nephropathy, other kidney diseases, and normal kidneys. The TBM from diabetics contained significantly more albumin (m ± SD; 2.75 ± 0.34 μg/mg) than the TBM from other diseases (1.00 ± 0.24 μg/mg) or normals (1.21 ± 0.26 μ/mg) (P < 0.0001). Similarly, diabetic GBM contained more albumin (2.25 ± 0.59 μg/mg) than other diseases (1.22 ± 0.55) or normals (1.31 ± 0.36 μg/mg) (P < 0.01–0.001). No differences were observed between the normal and other disease groups. Although there were no differences in hydroxyproline content, there was a highly significant correlation between the concentration of hydroxyproline and albumin in the diabetic TBM (r = 0.82), diabetic GBM (r = 0.70), and normal TBM (r = 0.79). Elution studies with different buffers on frozen sections of diabetic kidneys suggest that the albumin is relatively firmly bound. Although albumin is present in extracellular membranes of normal and diseased human kidneys, the concentration is higher in diabetes mellitus.
The BB Diabetic Rat: Profound T-Cell Lymphocytopenia
Authors: Jackson R , Rassi N , Crump T , Haynes B , Eisenbarth G S
Published: September 2013

Approximately 50% of Wistar “BB” rats spontaneously develop overt diabetes mellitus characterized by loss of β-cells and “insulitis.” To define abnormalities of immunoregulation in these rats, we quantitated their major circulating lymphocyte subsets. Independent of the development of diabetes, we found the BB rats to have a markedly increased percentage of circulating B lymphocytes which is secondary to a severe T-cell lymphocytopenia, with the major circulating T-cell subset reacting with monoclonal antibody W3/25 markedlydecreased. This lymphocytopenia is present in every animal studied and contrasted with studies of the nondiabetic Wistar strain from which the “BB” rats were developed.
Efficacy of the Insulin Pump in the Home Treatment of Pregnant Diabetics
Authors: Rudolf Mary C J , Coustan Donald R , Sherwin Robert S , Bates Susan E , Felig Philip , Genel Myron , Tamborlane William V
Published: September 2013

The efficacy and feasibility of the insulin infusion pump in pregnancy were examined in seven class D to FR diabetics, maintained on the pump at home from 10 to 29 wk gestation until delivery. An improvement in glucose control was achieved within the first month and sustained to term. Home monitoring demonstrated a fall in mean blood glucose levels from 135 mg/dl range 98–175, prepump) to 104 mg/dl (range 84–120) and a 25–30% reduction in standard deviations during pump treatment. Furthermore, glycosylated hemoglobin levels were normalized in each patient. During periodic inpatient evaluations, mean 24-h plasma glucose levels were slightly, but not significantly, lower after pump treatment (97 vs. 86 mg/dl). However, glycemic excursions were strikingly diminished; MAGE values and standard deviations fell by 45% and 34%, respectively. The total daily insulin dose required at the start of pump treatment was 31% less than the conventional dose used before the pump (P < 0.002). Thereafter the insulin dose increased by approximately 2.5 U/wk, with the basal infusion remaining at 40% of the total dose throughout the pregnancy. All infants were born at term, had no macrosomia or neonatal problems, and had normal intravenous glucose tolerance tests at 2 h of age. We conclude that the insulin infusion pump, managed at home, is a highly efficient way to achieve normal or near-normal glucose levels in the pregnant diabetic.
Acetylator Phenotypes and Type I (Insulin-dependent) Diabetics with Microvascular Disease
Authors: Bodansky H J , Drury P L , Cudworth A G , Evans D A Price
Published: September 2013

We have investigated the acetylator dimorphism in 55 type I (insulin-dependent) diabetics. The frequency of the fast phenotype (49%) was higher than in the general Northern European population (37%). Although this difference was not significant (chi squared = 2.64, P = 0.1) the combination of our data with data from two other studies produced a significant positive association between the fast acetylator phenotype and type I diabetes (P = 0.00013, relative risk = 2.0). These findings lend support to the concept that more than one genetic locus may be involved in the susceptibility to type I diabetes. No association was found between acetylator phenotypes and diabetic complications.
Adaptation of Glycolytic Enzymes: Glucose Use and Insulin Release in Rat Pancreatic Islets During Fasting and Refeeding
Authors: Burch Pamela Trueheart , Trus Michael D , Berner Donna K , Leontire Andrea , Zawalich Kathleen C , Matschinsky Franz M
Published: September 2013

Starvation refeeding experiments were conducted in rats to test the hypothesis that adaptation of glucokinase (the high Km component of glucose phosphorylation) could be the major determinant of glucose metabolism of pancreatic islet cells and of glucosestimulated insulin release. It was found that glucokinase of islet homogenates, glucose use by intact isolated islets, and glucose-induced insulin release as studied in a perifusion system were decreased after 24 h of fasting, whereas P-fructokinase and 3-P-glyceraldehyde DH were unaltered. After extended fasting (e.g., 120 h) all three enzymes were decreased but glucose use did not change any further. Refeeding normalized all parameters. These and previous results support the concept that glucokinase serves as the adaptive β-cell glucoreceptor relating blood glucose to insulin release.
Effect of Sucrose Overfeeding on Na,K-ATPase-Mediated 86Rb Uptake in Normal and ob/ob Mice
Authors: Flier Jeffrey S , Usher Patricia , Deluise Mario
Published: September 2013

When normal mice have their usual chow diets supplemented by free access to a solution of 10% sucrose, their caloric intake increases by about 30%. We have used this model to explore the effects of sucrose overfeeding on Na,K-ATPase-mediated cation transport. After 5 days of sucrose supplementation, Na,K-ATPase mediated K uptake is increased by 88% in liver slices and 26% in intact soleus muscles of these animals. Ob/ob mice are hyperphagic on an ad libitum chow diet, and they display even greater increments in caloric intake than do thin controls when similarly allowed access to sucrose. Despite hyperphagia while on a chow diet, Na,K-ATPase-mediated K uptake by liver slices of ob/ob mice is not significantly different from that of their thin littermates. In addition, Na, K-ATPase-mediated K uptake into liver slices of ob/ob mice does not significantly increase while on sucrose supplements. These findings demonstrate the influence of dietary factors on Na, K-ATPase-mediated ion transport in liver and muscle of normal mice, and suggest that ob/ob mice may have an impairment in such dietary control. These observations suggest an important role for nutritional factors in the overall regulation of monovalent cation transport, and may also have relevance for our understanding of the cellular mechanisms of dietary thermogenesis.
The Effect of Insulin on the Disposal of Intravenous Glucose: Results from Indirect Calorimetry and Hepatic and Femoral Venous Catheterization
Authors: DeFronzo R A , Jacot E , Jequier E , Maeder E , Wahren J , Felber J P
Published: September 2013

The effect of insulin on the disposal of intravenous glucose was examined employing the euglycemic insulin clamp technique in 24 normal subjects. When the plasma insulin concentration was raised by approximately 100 μU/ml, total glucose metabolism rose to 6.63 ± 0.38 mg/kg · min. Basal splanchnic (hepatic venous catheter technique) glucose production, 2.00 increased only slightly. These results suggest that the ability of higher doses of insulin to further stimulate glucose metabolism is primarily the result of increased glucose storage by peripheral tissues, most likely muscle. 0.15 ± mg/kg · min, reverted to a small net glucose uptake which averaged 0.33 mg/kg · min over the ensuing 2 h. This represented only 5% of the total glucose metabolized. In contrast, leg (femoral venous catheterization) glucose uptake rose from 1.18 ± 0.14 to 8.40 ± 1.06 mg/kg of leg wt. per min. If all muscles in the body respond similarly to those in the leg, muscle would account for 85% of the total glucose metabolism. To determine the relative contributions of glucose oxidation versus glucose storage by peripheral tissues following hyperinsulinemia, we performed euglycemic insulin clamp studies in combination with indirect calorimetry. Basal glucose oxidation, 1.21 ± 0.10 mg/kg min, rose to 2.28 ± 0.16 (P < 0.01), and this increase above baseline accounted for only 20% of the total glucose metabolized, 5.44 ± 0.38 mg/kg · min. Following insulin, glucose storage increased to 3.18 ± 0.34 mg/kg min and was responsible for 59% of the total glucose metabolized. These results indicate that the primary effect of insulin on muscle tissue is to enhance glucose storage, presumably as glycogen. When a higher degree of hyperinsulinemia (163 ± 19 μl/ml) was created while maintaining euglycemia, total glucose metabolism (7.99 ± 0.58) and glucose storage (5.30 ± 0.80) both increased (P < 0.01) compared with the lower dose insulin clamp study, but glucose oxidation (2.70 ± 0.16 mgμkg min)increased only slightly. These results suggest that the ability of higher doses of insulin to further stimulate glucose metabolism is primarily the result of increased glucose storage by peripheral tissues, most likely muscle.
Complement-fixing Islet Cell Antibodies from Some Diabetic Patients Alter Insulin Release In Vitro
Authors: Sai P , Boitard Chr , Debray-Sachs M , Pouplard A , Assan R , Hamburger J
Published: September 2013

To explore humoral immunity in insulin-dependent diabetic (IDDM) patients, we studied insulin release from isolated mouse islets stimulated by glucose + theophylline after incubation with the sera of these patients and complement. Eleven of 21 IDDM sera suppressed the stimulated insulin release while the arginine-stimulated glucagon release remained unchanged. Morphologic evidence and the trypan-blue exclusion test suggested that the suppression of insulin release was due to a cytotoxic effect of the sera.

No beta-cell inhibition or morphologic damage was detectable in the presence of sera from 30 healthy subjects, 8 non-insulin-dependent diabetic patients, and 5 nondiabetic patients with autoimmune diseases. Beta-cell inhibition by IDDM sera was not observed when complement was omitted. After serum fractionation, the cytotoxic potency of IDDM sera was located in the immunoglobulin G fraction. Using human islets, insulin release was suppressed by 3 of 6 IDDM sera.

Complement-dependent cytotoxicity was found in 1 of 5 recent-onset IDDM patients and 11 of 16 IDDM patients with autoimmune phenomena. It was associated in all cases with the presence of islet cell antibodies as detected by immunofluorescence, and with the presence of circulating lymphocytes which suppressed insulin release in vitro. Complement-fixing antibodies may contribute to the selective beta-cell damage in IDDM.
Long-term Continuous Intraperitoneal Insulin Infusion with an Implanted Remote-Controlled Insulin Infusion Device
Authors: Irsigler K , Kritz H , Hagmüller G , Franetzki M , Prestele K , Thurow H , Geisen K
Published: September 2013

This is a report of the implantation and first 100-day operation using a remote-controlled programmable insulin infusion device in an insulin-dependent diabetic. To prevent insulin aggregation, a special surface-active polymer developed by Hoechst AG, Frankfurt, was used as an additive.

Implantation was completed on April 8,1981, and good metabolic control was reached immediately and has continued to date (July 1981), with this unit providing the only source of insulin. There have been no hypoglycemic attacks. Patient acceptance is very good. The Siemens unit, PFA 01 (external) and DFA 01 (implanted) has proved reliable and precise.
Prevention of Diabetic Nephropathy by Diet Control in the db/db Mouse
Authors: Lee Stanley M , Bressler Rubin
Published: September 2013

Diabetes in the C57BL/KsJ(db/db) mouse is initially expressed as hyperinsulinemia, followed by hyperphagia, progressive obesity, and widespread pathologic abnormalities. This study was designed to evaluate the effects of metabolic control on the natural history of the diabetic nephropathy. Beginning at 1 mo of age and continuing for 12 wk, diabetic mice were subjected to controlled dietary restriction, such that their weight was maintained similar to that of age-matched, nondiabetic heterozygotes. Diet-restricted diabetics were compared with diabetics fed ad libitum and heterozygote nondiabetics.

Significant lowering of fasting blood glucose, water intake, and plasma insulin was achieved by diet restriction. The diet-restricted diabetics demonstrated enhanced metabolic efficiency, consuming approximately half as much food as the nondiabetics, while maintaining a similar weight.

Diabetics fed ad libitum evidenced well-defined renal lesions that included 3+ to 4+ immunoglobulin deposition in the glomerular mesangium, and generalized mesangial matrix expansion. These lesions were completely prevented in diet-restricted diabetics whose glomeruli were normal by light microscopy, and demonstrated trace to 1 + mesangial immunoglobulin deposition, features identical in all respects to the nondiabetics.

These results indicate that diabetic control achieved by prevention of obesity in the db/db mouse prevents the development of diabetic nephropathy.
Identification of Human Mononuclear Leukocytes Bearing Receptors for Somatostatin and Glucagon
Authors: Bhathena Sam J , Louie James , Schechter Geraldine P , Redman Robert S , Wahl Larry , Recant Lillian
Published: September 2013

Mononuclear leukocytes (MNL) were isolated from human blood by Ficoll-Hypaque. These cells were further separated into lymphocyte (L) and monocyte (M) enriched fractions. L contained 99% lymphocytes and M contained 74% monocytes, a threefold enrichment over MNL. Specific binding of somatostatin, glucagon, and insulin was measured in the three fractions. Binding of all three hormones in the M fraction was increased by a factor of 3 compared with MNL and was linear with cell number. Binding of glucagon and insulin to the L fraction was very low while, in contrast, somatostatin binding was substantial and linear with lymphocyte number.

Autoradiography confirmed the binding of glucagon to monocytes and of somatostatin to both monocytes and lymphocytes.

Somatostatin is the first of the peptide hormones shown to bind to both types of circulating mononuclear cells, perhaps complicating quantification of somatostatin binding in disease states in which differential alteration of binding to lymphocytes or monocytes might occur.
Diabetes and Atherosclerosis: an Overview
Authors: Steiner George
Published: September 2013

Atherosclerosis is the most common complication of diabetes. Epidemiologic and pathophysiologic evidence suggest a number of possible reasons for this. They include alterations in lipoproteins, platelets, soluble clotting factors, the balance of prostacyclin-thromboxane, blood pressure regulation, and arterial smooth muscle cell metabolism and proliferation. Many of these alterations may accompany hyperinsulinemia and may account for the recent evidence that hyperinsulinemia is a risk factor for atherosclerosis. Advances in this area will require the recognition that neither diabetes nor atherosclerosis are single disorders. Furthermore, new approaches are needed to study these disorders in which there may be many years of very subtle changes before any end point is apparent.
Cellular and Molecular Biology of Lipoprotein Metabolism in Atherosclerosis
Authors: Mahley Robert W
Published: September 2013

Despite a significant decrease in mortality from cardiovascular disease in the US over the past decade, coronary artery disease, more specifically myocardial infarction, remains the leading cause of death in our country, and in most Westernized countries of the world. The disease process of atherosclerosis causes coronary heart disease; yet, despite considerable progress, much remains to be learned about the basic mechanisms responsible for this disease process. It is the purpose of this paper to review the recent advances that are contributing to our understanding of the important role of plasma lipoproteins in atherosclerosis and the role of dietary fat and cholesterol in altering plasma lipoprotein metabolism.
Physical Factors Important in the Development of Atherosclerosis in Diabetes
Authors: McMillan Donald E
Published: September 2013

Circulation of the blood is a process controlled by physical laws. The same physical laws also determine the sites of atherosclerotic plaques. Our understanding of their role in atherogenesis is aided by a review of (1) the difference between a solid and fluid, (2) strain and shear or strain rate and shear rate as describers of motion, (3) the distinction between force as pressure and as shear stress, (4) the effects of viscosity and inertia on fluid motion, and (5) the nonlinear responses of blood and blood vessels. Moving blood affects the vessel wall principally through shear stress, the force due to its viscosity applied parallel to the surface of the vessel. Excessive shear stress occurs near the orifices of branches of the aorta, the arterial areas where atherosclerotic plaques develop. It is produced by a change in blood flow pattern at these sites. Arterial stiffening in diabetes reduces the ability of the branches of the aorta to dilate during systole, a motion that helps to control high wall shear stress. At wall shear stress levels under 400 dynes/cm2, a value only modestly higher than that normally achieved near the orifices of the major arterial branches, the endothelial lining of the arterial wall becomes disrupted, allowing entry of plasma proteins and lipids. Blood viscosity elevation in diabetes, linked to enhanced erythrocyte aggregation and reduced erythrocyte deformability, adds to the shear stress at the vessel wall, favoring increased lipid entry. Exposed to a high lipid influx secondary to excessive wall shear stress, the arterial wall must rely on physical as well as chemical means to remove the lipids. Subendothelial motion generated by diastolic arterial contraction and systolic expansion appears to cause plasmalemmal vesicle formation and dissolution, an event probably important in the removal process. The combination of arterial stiffening and hemorheologic disturbance adds to the burden of increased plasma lipids to favor the development of atherosclerosis in diabetes.
Differential Time Course of Glucagon's Effect on Glycogenolysis and Gluconeogenesis in the Conscious Dog
Authors: Cherrington A D , Williams P E , Shulman G I , Lacy W W
Published: September 2013

The evanescence of glucagon's effect on glucose production (GP) is well documented, but it is unclear (1) whether this response involves both glycogenolysis and gluconeogenesis and (2) whether the liver becomes dependent on the increased glucagon level for the maintenance of a basal supply of glucose. To answer these questions, conscious overnight-fasted dogs were given somatostatin (0.8 μg/kg · min) plus basal intraportal replacement amounts of insulin (273 μU/kg min) and glucagon (0.65 ng/kg · min) for 2 h, after which the rate of glucagon infusion was increased fourfold for 3 h and then returned to basal for 1.5 h. GP was determined using a primed infusion of [3-3H[ glucose, and gluconeogenesis (GNG) was estimatedby determining the conversion rate of alanine and lactate to glucose.

An increase in the plasma glucagon level from 55 to 206 pg/ml resulted in an initial 180% increase in GP, followed by a decline such that after 3 h of hyperglucagonemia GP was increased by only 41%. Contrary to overall GP, gluconeogenesis increased progressively throughout the hyperglucagonemic period, eventually reaching a rate 3 times basal. Restoration of the basal glucagon level (63 pg/ml) caused a marked decline in GP and GNG. In fact, GP fell to a level 29% below the initial control rate and consequently the plasma glucose level fell rapidly. The data suggest that (1) the downregulation of glucagonstimulated GP is attributable to a decline in glycogenolysis and not gluconeogenesis, and (2) following adaptation to the hormone, the liver becomes dependent on the elevated glucagon concentration for the maintenance of basal glucose production.
Pancreatic D-Cell Recognition of D-Glucose: Studies with D-Glucose, D-Glyceraldehyde, Dihydroxyacetone, D-Mannoheptulose, D-Fructose, D-Galactose, and D-Ribose
Authors: Hermansen K
Published: September 2013

To investigate how the D-cell recognizes the glucose stimulus, the hormone response to (1) glucose, (2) the trioses glyceraldehyde and dihydroxyacetone, (3) the metabolic blocker, mannoheptulose, and (4) the lowor nonmetabolized sugars galactose, fructose, or ribose were studied using the isolated dog pancreas. We found (1) a sigmoidal relationship between extracellular glucose concentrations and the somatostatin release. The threshold concentration was around 5 mM and the largest increase in somatostatin release occurs between 5 and-10 mM of glucose. (2) Glyceraldehyde at concentrations ranging between 1.25 and 5 mM stimulated the release of somatostatin, whereas the higher concentrations of 10 and 20 mM were suppressive. Dihydroxyacetone (11 mM), also initiated somatostatin release in the absence of glucose. Both of the trioses stimulated B- and inhibited A-cell secretion. (3) Mannoheptulose (5 mM) attenuated somatostatin and insulin secretion to 8.3 mM glucose, while it augmented glucagon output. In contrast, mannoheptulose (5 mM) did not affect D-, A-, or B-cell responses to glyceraldehyde (5 mM) in the absence of glucose. (4) The somatostatin, insulin, and glucagon release remained unchanged when 8.3 mM of either galactose, fructose, or ribose was added. The results suggest that the initiation of glucose-mediated D- as well as Aand B-cell responses depends on the metabolism of the sugar.
The Inhibition of Islet Superoxide Dismutase by Diabetogenic Drugs
Authors: Crouch Rosalie K , Gandy Samuel E , Kimsey Gary , Galbraith Richard A , Galbraith Gillian M P , Buse Maria G
Published: September 2013

The enzyme superoxide dismutase (SOD) is a scavenger of superoxide radicals and protects the integrity of cell membranes. We previously reported that streptozotocin inhibits the SOD activity of erythrocytes and retinae in vivo and in vitro. We now report that the three major diabetogenic drugs, i.e., alloxan, streptozotocin, and Vacor (in order of increasing potency), interact with erythrocyte Cu-Zn SOD in vitro. Maximum inhibition of erythrocyte SOD of man, dog, rat, and cow is 40% and is achieved within 10 min. At submaximal doses the effect of the three drugs is additive. Inhibition induced by streptozotocin, but not by the other two agents, is reversible by dialysis. Alloxan (80 mg/kg), like streptozotocin, also inhibits erythrocyte SOD activity when injected i.v. into rats. Glucose or 3- o-methylglucose does not prevent SOD inhibition by alloxan or streptozotocin in vitro. Injection of glucose before alloxan prevents the development of diabetes, but does not prevent alloxan-lnduced inhibition of erythrocyte SOD.

SOD is present in the islets of Langerhans of rats and dogs, as demonstrated by biochemical assay of isolated islets and by immunofluorescent staining of frozen pancreases. The specific activity of SOD in the islets exceeds that of the exocrine pancreas more than 100-fold. The islet SOD is of the Cu-Zn type, since it is inhibited by KCN, and not by chloroformethanol. The mobility of the islet enzyme on polyacrylamlde disc gel electrophoresis is different from that of erythrocyte SOD. Streptozotocin, alloxan, and Vacor Inhibit the activity of islet SOD in vitro; the rate and magnitude of inhibition is the same as that observed with erythrocyte SOD. The Mn SOD of liver mitochondria is not affected by the diabetogenic drugs. It is suggested that the inhibitory effect of the diabeto- genie drugs on islet cell SOD may contribute to their cytotoxicity, and that changes in the amount or activity of this protective enzyme in β-cells may play a role in determining their vulnerability to noxious agents.
The Cellular Stimuli for the Rejection of Established Islet Allografts
Authors: Zitron Ian M , Ono Junko , Lacy Paul E , Davie Joseph M
Published: September 2013

Previous work from our laboratory has indicated that the transplantation of pancreatic islets is a feasible approach to the problem of diabetes. A major obstacle to transplantation is presented by passenger leucocytes, which contaminate the preparations and can lead to the prompt rejection of fresh islets. We have extended our previous studies on the rejection of islet allografts by challenging transplanted animals with enriched lymphoid cell populations prepared from animals both syngeneic to the transplanted islets and third party. Rapid and complete rejection was observed when the challenge peritoneal exudate cell population was syngeneic with the transplanted islets; rejection was determined by both functional and histologic criteria. Peritoneal exudate cells from a thirdparty rat strain induced delayed and variable effects upon the function of the transplant. In contrast, splenic T-cells were capable of inducing rejection, regardless of the strain of origin, though the time course of T-cell-induced rejection was slower than that observed by syngeneic peritoneal exudate cells. Finally, splenic B-cells completely failed to induce rejection.

Our data indicate that at least two mechanisms exist by which the rejection of islet allografts may be triggered. The first is a haplotype-specific mechanism initiated by a cell type present at high frequency in peritoneal exudate cells; these are probably macrophages. The second mechanism is initiated by immunocompetent T-cells; this mechanism shows no haplotype specificity. We suggest that both macrophages and T-cells must be considered when devising protocols for the removal of passenger leucocytes from allografts.