bluuebunny/crossref_metadata_2025 huggingface dataset:
Neonatal Tolerization With Glutamic Acid Decarboxylase But Not With Bovine Serum Albumin Delays the Onset of Diabetes in NOD Mice
Authors: Petersen Jacob Sten , Karlsen Allan E , Markholst Helle , Worsaae Anne , Dyrberg Thomas , Michelsen Birgitte
Published: September 2013

To test the role of glutamic acid decarboxylase (GAD65) or bovine serum albumin (BSA) autoimmunity in the pathogenesis of diabetes, GAD65 or BSA was injected intraperitoneally into neonatal female NOD mice (100 micrograms/mouse of each protein). Treatment with GAD65, but not with BSA, significantly delayed the onset of diabetes compared with control mice (P < 0.05). At 18 weeks, 6 of 10 control mice compared with 0 of 10 GAD65-treated mice (P = 0.005) and 7 of 14 BSA-treated mice had developed diabetes. However, after 79 weeks, 6 of 10 of the GAD65-treated mice were diabetic compared with 9 of 10 of the control mice and 12 of 14 of the BSA-treated mice. In GAD65-treated mice without diabetes, insulitis was markedly reduced compared with control or BSA-treated mice (P < 10−4). To further elucidate why GAD becomes an autoantigen, the expression in NOD mice islets was studied. Quantitative immunohistochemistry revealed that islet cell expression of GAD was increased in 5-week-old NOD mice compared with BALB/c mice (P = 0.02). With the occurrence of insulitis (9–15 weeks), the GAD expression was further increased relative to 5-week-old NOD mice (P < 0.02). In conclusion, GAD, but not BSA, autoimmunity is important for the development of diabetes in NOD mice. Furthermore, concordant with the appearance of insulitis, the GAD expression increased in NOD mouse islets, which could possibly potentiate the β-cell-directed autoimmunity.
Dynamics of Glucose Production and Uptake Are More Closely Related to Insulin in Hindlimb Lymph Than in Thoracic Duct Lymph
Authors: Poulin Reneé A , Steil Garry M , Moore Donna M , Ader Marilyn , Bergman Richard N
Published: September 2013

We previously reported a striking similarity between the dynamics of both glucose turnover and thoracic duct lymph insulin during euglycemic clamps (J Clin Invest 84:1620, 1989), which suggested that transendothelial insulin transport (TET) is rate-limiting for insulin action in vivo. Thoracic duct lymph, however, is primarily derived from insulin-insensitive tissues, which raises questions as to the physiological significance of this relationship. The relationship between glucose turnover and TET was thus examined in insulin-sensitive tissues by the simultaneous measurement of insulin in plasma, thoracic duct lymph, and hindlimb lymph during euglycemic clamps in normal anesthetized dogs (n = 8). Clamps consisted of two 3-h phases: a 0.6 mU · min−1 · kg−1 insulin infusion (activation phase) followed by termination of the insulin infusion (deactivation phase). Lymph insulin was < plasma insulin during both phases (P < 0.01) with steady-state hindlimb (120 ± 12 pM) and thoracic duct lymph insulin (138 ± 12 pM) 38 and 45%, respectively, lower than steady-state plasma insulin (222 ± 24 pM) at the end of the activation phase (P < 0.05). Also, the rate of increase of lymph insulin was slower than plasma insulin during hormone infusion; half-time to steady-state was 8.8 ± 2.0 min for plasma insulin, but longer for thoracic (25.8 ± 3.5) and hindlimb lymph insulin (40.7 ± 5.7 min). A very close relationship was observed during activation between the rate of increase of glucose uptake (Rd) and the increase in hindlimb lymph insulin (r2 = 0.92); this relationship was weaker for thoracic lymph (r2 = 0.74) and much weaker between glucose uptake and plasma insulin (r2 = 0.35). These data support the concept that interstitial insulin (represented by hindlimb lymph) is the signal that determines glucose uptake by insulin-sensitive tissues and that the rate of increase of glucose uptake is determined by transendothelial insulin transport into insulin-sensitive tissue. Also, during activation, hindlimb lymph insulin was a very strong predictor of the rate of suppression of hepatic glucose output (HGO) (r2 = 0.96), and the correlation with HGO was stronger than that for thoracic lymph (r2 = 0.85). The evidence that the rate of increase of Rd and the rate of suppression of HGO during insulin infusion are very strongly predicted by the time course of insulin in hindlimb lymph is consistent with the single-gateway hypothesis: the insulin transport rate across endothelium in insulin-sensitive tissue (skeletal muscle) determines the rate of glucose utilization and the suppression of hepatic glucose output. It is suggested that there is a yet-undefined signal that controls HGO generated at the level of insulin-sensitive peripheral tissues.
Islet-Specific T-Cell Clones From the NOD Mouse Respond to β-Granule Antigen
Authors: Bergman Barbara , Haskins Kathrin
Published: September 2013

Islet-reactive T-cell clones from NOD mice provide an important approach to the investigation of antigens with relevance to type I diabetes. To identify a source of β-cell antigen suitable for biochemical studies, we have used two islet-specific, diabetogenic T-cell clones to test β-tumor cells. β-tumor cell lines, maintained in continuous culture, were found to lose antigenicity rapidly. However, cells harvested directly from β-tumors arising spontaneously in the transgenic NOD/Lt-Tg(RIPTag)1Lt mouse proved to be a potent source of β-cell antigen for the T-cell clones. Subcellular fractionation of β-tumor cells showed that the T-cell antigen was highly enriched in the β-granule fraction and that this activity was associated with the granule membrane.
Higher Maternal Than Paternal Inheritance of Diabetes in GK Rats
Authors: Gauguier Dominique , Nelson Isabelle , Bernard Catherine , Parent Véronique , Marsac Cécile , Cohen Daniel , Froguel Philippe
Published: September 2013

Results from crosses between Goto-Kakizaki (GK) rats, which exhibit spontaneous non-insulin-dependent diabetes mellitus (NIDDM), and outbred nondiabetic Wistar rats have demonstrated an effect of maternal inheritance on diabetes in offspring of the first generation (F1). At 6 weeks of age, F1 offspring of sex-directed crosses exhibited plasma glucose values intermediate between GK and Wistar parents. Hyperglycemia in F1 rats born of female GK rats (F1GK) was more marked than in those born of female Wistar (F1W) rats. At 3 months of age, F1 rats showed a marked impairment of both glucose tolerance and insulin secretion, which was intermediate between GK and Wistar rats. Glucose intolerance was more pronounced in F1GK rats than in F1W. By contrast, insulin secretion in F1W rats was more deteriorated than in F1GK rats. No deletion in mitochondrial DNA was observed in the GK rats, which decreased the possibility of a mitochondrial inheritance effect as an explanation of our findings. These data support a polygenic model in diabetes inheritance of NIDDM and suggest that, in addition to genetic factors, a perturbed maternal metabolism can contribute to its inheritance.
Impact of Diabetic Inheritance on Glucose Tolerance and Insulin Secretion in Spontaneously Diabetic GK-Wistar Rats
Authors: Abdel-Halim Samy M , Guenifi Amel , Luthman Holger , Grill Valdemar , Efendic Suad , Östenson Claes-Gö
Published: September 2013

The impact of genetic factors and maternal diabetes on glucose tolerance and pancreatic β-cell function was studied in first generation (F1) offspring generated in crosses between the spontaneously diabetic Goto-Kakizaki (GK)-Wistar rat and normoglycemic control Wistar rats (W). The (GK × W) F1 hybrids were offspring of either male GK (mGK) and female Wistar (fW) (mGK × fW) or male Wistar (mW) and female GK (fGK) (mW × fGK) rats. Already at 8 days of age, blood glucose levels were elevated in GK (7.6 ± 0.5 vs. 4.8 ± 0.3 mM in W; P < 0.001) and in F1 rats (6.0 ± 0.3 in mGK × fW and 6.6 ± 0.4 mM in mW × fGK; both P < 0.01 vs. W). In 2-month-old male rats, glucose (2 g/kg, intraperitoneally) markedly increased blood glucose levels after 60 min in GK rats (18.1 ± 0.6 vs. 5.5 ± 0.3 mM in W; P < 0.001) and moderately increased levels in F1 rats (9.9 ± 0.9 in mGK × fW and 11.6 ± 1.0 mM in mW × fGK, both P < 0.01 vs. W). Similar patterns were obtained in female rats. Repeated backcrossing of F1 with W rats successively improved glucose tolerance. In perfused pancreases of male rats, the 20-min insulin response to 16.7 mM glucose was −7.44 ± 5.18 pmol in GK rats, 71.57 ± 12.25 pmol in W rats, 9.00 ± 0.89 pmol in mGK × fW rats, and 18.20 ± 3.97 pmol in mW × fGK rats. In female W rats, the glucose-induced insulin response was significantly lower than in males (P < 0.05). However, as in males, insulin responses to glucose were impaired in both GK and F1 female rats. Arginine-induced insulin release was similar in all groups. In mGK × fW, glucose-stimulated somatostatin release was 50% of that in W rats, whereas arginine-stimulated responses of glucagon and somatostatin were not different from W rats. Pancreatic contents of insulin and glucagon were similar in mGK × fW and W rats, whereas somatostatin content was lower in mGK × fW rats (P < 0.05). In conclusion, the diabetic state in GK and F1 rats was evident early in life. Hybrid rats were intermediate between W and GK rats with regard to glucose tolerance and glucose-stimulated insulin response in vitro, but had normal pancreatic insulin content. Results of repeated backcrossing of F1 rats with W rats showed that genes in >1 locus contribute to the diabetic state. Furthermore, the absence of significant differences between impact of maternal and paternal origin of the GK genes for glucose intolerance suggests that hyperglycemia in utero does not influence the severity of diabetes in the F1 offspring.
Assessment of Insulin Action in NIDDM in the Presence of Dynamic Changes in Insulin and Glucose Concentration
Authors: Katz Harold , Homan Mal , Jensen Michael , Caumo Andrea , Cobelli Claudio , Rizza Robert
Published: September 2013

Both glucose and insulin are important regulators of glucose uptake and hepatic glucose release. Because insulin concentrations rarely if ever increase under daily living conditions, unless glucose concentrations also increase, we sought to determine whether hepatic and extrahepatic responses to changes in insulin and glucose concentration are impaired in patients with non-insulin-dependent diabetes mellitus (NIDDM). To address this question, glucose metabolism was measured in diabetic and nondiabetic subjects. A computer-driven infusion system was used to produce a nondiabetic postprandial insulin profile in both groups while sufficient exogenous glucose was infused to mimic nondiabetic postprandial glucose concentrations. Although NIDDM was associated with greater (P < 0.05) hepatic glucose release both before and during the prandial insulin infusion, suppression did not differ in the diabetic and nondiabetic subjects (−1.06 ± 0.20 vs. −0.86 ± 0.15 mmol/kg every 4 h). In contrast, stimulation of both glucose disappearance (0.77 ± 0.27 vs. 1.68 ± 0.27 mmol/kg every 4 h) and forearm glucose uptake (187 ± 81 vs. 550 ± 149 μmol/dl every 4 h) was lower (P < 0.05) in diabetic than in nondiabetic subjects. Thus, despite increased basal rates of glucose production, obese individuals with NIDDM had decreased stimulation of glucose disappearance but normal suppression of hepatic glucose release in response to nondiabetic prandial glucose and insulin concentrations. These data indicate that the increase in glucose that occurs with carbohydrate ingestion is likely to compensate for hepatic but not extrahepatic insulin resistance.
Islet Amyloid Polypeptide in Human Insulinomas: Evidence for Intracellular Amyloidogenesis
Authors: O'Brien Timothy D , Butler Alexandra E , Roche Patrick C , Johnson Kenneth H , Butler Peter C
Published: September 2013

Amyloid deposits that characteristically form in the pancreatic islets of patients with non-insulin-dependent diabetes mellitus (NIDDM) and in insulinomas are both derived from islet amyloid polypeptide (IAPP). Evidence from previous studies has suggested that deposition of IAPP-derived amyloid is related to inherent amyloidogenic sequences present within normal human IAPP, together with an increased production and local concentration of IAPP. However, whether the aggregation of IAPP to form amyloid fibrils is primarily an intra- or extracellular event is not clear. To address this question, we studied 20 human insulinomas by light and electron microscopy. By light microscopy, amyloid deposits were demonstrated in 13 of 20 (65%) human insulinomas. Furthermore, evaluation of Congo red-stained tumor sections showed small, globular or irregular, congophilic amyloid deposits within the cytoplasm of many tumor cells in 10 of 13 (77%) amyloid-containing insulinomas. Dense, punctate areas of IAPP immunoreactivity within tumor cells corresponded with the congophilic intracellular deposits. Ubiquitin immunoreactivity also was observed as punctate intracellular labeling and within large extracellular amyloid deposits. Among the 10 insulinomas available for electron microscopic evaluation, pathological IAPP-immunoreactive (immunogold) deposits were found in 3 of 5 insulinomas in which amyloid was demonstrated by light microscopy and in none of 5 tumors found negative for amyloid by light microscopy. Morphology of IAPP-immunoreactive deposits varied from those with the classical distinct 7- to 10-nm diameter nonbranching fibrils to those with distinct but faint fibrillarity to those without discernable fibrils. In each of the 3 tumors with ultrastructurally demonstrable amyloid deposits, intracellular aggregates of IAPP-immunoreactive amyloid fibrils were observed either free in the cytoplasmic matrix or in membrane-bound structures. Intracellular IAPP-immunoreactive deposits were up to 10 urn in the greatest dimension. Free intracellular aggregates of amyloid fibrils sometimes contained degenerating secretory vesicles and fragments of membranous organelles. These observations suggest that IAPP-derived amyloid deposits are initially formed intracellularly and are subsequently released to the extracellular space by exocytosis of the membrane-bound structures and/or after necrosis of the tumor cells. Our observations raise the possibility that IAPP-derived islet amyloid deposits (characteristically present in NIODM patients) also may be initially formed within the cytoplasm of β-cells, thus leading to β-cell necrosis and a reduction of β-cell mass as seen in NIDDM.
Vanadate Augments Insulin-Stimulated Insulin Receptor Kinase Activity and Prolongs Insulin Action In Rat Adipocytes: Evidence for Transduction of Amplitude of Signaling into Duration of Response
Authors: Fantus I George , Ahmad Ferhaan , Deragon Guy
Published: September 2013

Vanadate, a protein tyrosine phosphatase inhibitor, preserves insulin-stimulated lipogenesis after removal of insulin. To investigate the mechanism of this action of vanadate, lipogenesis was studied in isolated rat adipocytes exposed to vanadate for 60 min followed by insulin for 15 min at 37°C. Vanadate (10–50 μM) prolonged insulin-stimulated lipogenesis. The half-time (t½) of the decay in insulin (0.34 nM)-stimulated lipogenesis after removal of insulin by washing in pH 7.0 followed by pH 7.6 buffer was 21 min in the absence and 59 min in the presence of vanadate. During these conditions, vanadate did not alter insulin binding nor the removal of insulin by the series of washes. In contrast to lipogenesis, the t½ of the decay in insulin receptor tyrosine kinase (IRK) activity, assayed with the artificial substrate Poly[Glu:Tyr] (4:1), was not significantly prolonged by vanadate (6 vs. 6.8 min). However, insulin-stimulated IRK activity was markedly augmented by vanadate to 319 ± 19% of insulin alone, associated with a similar augmentation of phosphotyrosine incorporation into the insulin receptor beta-subunit determined by Western blotting with antiphosphotyrosine antibodies. To determine the relationship between prolongation of lipogenesis and the increase in IRK, adipocytes were exposed to 17.2 nM insulin to activate the IRK to the same extent as insulin (0.34 nM) plus vanadate (maximum activation). During these two conditions, the decay of lipogenesis was similar and after stimulation with 17.2 nM insulin was not prolonged by vanadate. We conclude that vanadate prolongs insulin action at insulin concentrations that do not maximally activate the IRK by augmenting IRK activity.The data suggest that the amplitude of the insulin signal, the IRK, is transduced into duration of response, lipogenesis. Thus activation of receptor above that required for a maximum biological response results in prolongation of action.
[Lys(B28), Pro(B29)]-Human Insulin: A Rapidly Absorbed Analogue of Human Insulin
Authors: Howey Daniel C , Bowsher Ronald R , Brunelle Rocco L , Woodworth James R
Published: September 2013

[Lys(B28, Pro(B29)]-human insulin (LYSPRO) is an insulin analogue in which the natural amino acid sequence of the B-chain at positions 28 and 29 is inverted. These changes result in an insulin molecule with a greatly reduced capacity for self-association in solution. These clinical studies were designed to compare LYSPRO with human Regular insulin after subcutaneous injection in humans. We wanted to evaluate the effect of adding zinc to LYSPRO on its pharmacokinetics and pharmacodynamics. In addition, we compared the pharmacokinetics and pharmacodynamics of LYSPRO and human Regular insulin after subcutaneous injection to those of human Regular insulin given intravenously. Thus, we compared four treatments: solutions of zinc-free LYSPRO given subcutaneously (A), zinc-containing LYSPRO given subcutaneously (B), human Regular insulin given subcutaneously (C), and human Regular insulin given intravenously (D). We gave a 10-U dose of each treatment to 10 healthy (nondiabetic) men during glucose clamps. Serum insulin concentrations peaked more than two times higher (maximum serum insulin level [Cmax], 698 vs. 308 pM, A vs. C) and in < half the time (time to Cmax [Tmax], 42 vs. 101 min, A vs. C) after subcutaneous injection of zinc-free LYSPRO. At the same time, the glucose infusion rate peaked in about half the time (time to maximum glucose infusion rate [TRmax], 99 vs. 179 min, A vs. C) and was slightly but not significantly higher (maximum glucose infusion rate [Rmax], 3.1 vs. 2.2 mmol/min, A vs. C) than that of human Regular insulin. Although the addition of zinc retarded the absorption of LYSPRO slightly (Cmax, 550 vs. 698 pM, B vs. A), zinc-containing LYSPRO retained its distinct profile (Tmax 53 vs. 42 min, B vs. A). LYSPRO displays faster pharmacodynamic action than human Regular insulin when injected subcutaneously
Linkage Analysis of Acute Insulin Secretion With GLUT2 and Glucokinase in Pima Indians and the Identification of a Missense Mutation in GLUT2
Authors: Janssen Rachel C , Bogardus Clifton , Takeda Jun , Knowler William C , Thompson D Bruce
Published: September 2013

The acute insulin response (AIR), a measure of pancreatic β-cell function, aggregates in families and is a predictor for the development of non-insulin-dependent diabetes mellitus (NIDDM) in insulin-resistant Pima Indians. To assess the genetic components of AIR and NIDDM, polymorphic dinucleotide repeat regions in two candidate genes, the liver/islet glucose transporter gene (GLUT2) and the glucokinase gene, were evaluated. Sib-pair linkage analyses were performed to determine if linkage exists between these marker loci and measurements of AIR and NIDDM. No linkage was found between glucokinase and either AIR or NIDDM. Robust sib-pair linkage analyses suggest linkage between GLUT2 and acute insulin response (P = 0.04), but no linkage was observed with NIDDM. The coding region of the GLUT2 gene was screened for mutations using polymerase chain reaction-single-strand conformation polymorphism analysis. A single base change was identified in exon 3 in ∼5% of the study population, and it constitutes the first reported mutation in the human GLUT2 gene. This base change resulted in an amino acid substitution (Thr110→Ile110) in the second membrane-spanning region of the GLUT2 protein. No significant association was noted between AIR and the presence or absence of the mutation. Thus, this mutation in GLUT2 is unlikely the cause of a low AIR in Pima Indians.
The Contribution of Insulin-Dependent and Insulin-Independent Glucose Uptake to Intravenous Glucose Tolerance in Healthy Human Subjects
Authors: Kahn Steven E , Prigeon Ronald L , McCulloch David K , Boyko Edward J , Bergman Richard N , Schwartz Michael W , Neifing James L , Ward W Kenneth , Beard James C , Palmer Jerry P
Published: September 2013

Glucose disposal occurs by both insulin-independent and insulin-dependent mechanisms, the latter being determined by the interaction of insulin sensitivity and insulin secretion. To determine the role of insulin-independent and insulin-dependent factors in glucose tolerance, we performed intravenous glucose tolerance tests on 93 young healthy subjects (55 male, 38 female; 18–44 years of age; body mass index, 19.5–52.2 kg/m2). From these tests, we determined glucose tolerance as the glucose disappearance constant (Kg), calculated β-cell function as the incremental insulin response to glucose for 19 min after an intravenous glucose bolus (IIR0-19), and derived an insulin sensitivity index (SI) and glucose effectiveness at basal insulin (SG) using the minimal model of glucose kinetics. To eliminate the effect of basal insulin on SG and estimate insulin-independent glucose uptake, we calculated glucose effectiveness at zero insulin (GEZI = SG [SI × basal insulin]). Insulin-dependent glucose uptake was estimated as SI × IIR0-19, because the relationship between SI and β-cell function has been shown to be hyperbolic. Using linear regression to determine the influence of these factors on glucose tolerance, we found that GEZI was significantly related to Kg (r = 0.70; P < 0.0001), suggesting a major contribution of insulin-independent glucose uptake to glucose disappearance. As expected, SI × IIR0-19 also correlated well with Kg (r = 0.74; P < 0.0001), confirming the importance of insulin-dependent glucose uptake to glucose tolerance. Although IIR0-19 alone correlated with Kg (r = 0.35; P = 0.0005), SI did not (r = 0.18; P > 0.08). By multiple regression, 72% of the variance in Kg could be explained by GEZI and S1 × IIR0-19 (r = 0.85; P < 0.0001). We conclude that insulin-independent glucose uptake is a major determinant of intravenous glucose tolerance and that the interaction of insulin sensitivity and insulin levels are more important than either factor alone as a determinant of intravenous glucose tolerance.
The Squatting Test: A Useful Tool to Assess Both Parasympathetic and Sympathetic Involvement of the Cardiovascular Autonomic Neuropathy in Diabetes
Authors: Marfella Raffaele , Giugliano Dario , di Maro Giosué , Acampora Ritta , Giunta Riccardoxs , D'Onofrio Felice
Published: September 2013

The heart rate responses observed after both squatting and standing are thought to be of reflex nature and may be useful to assess the functional integrity of parasympathetic and sympathetic nerves in diabetes. In the standard maneuver, each subject stood still for 3 min, then squatted down for 1 min, and at last stood up during an inspiratory phase. In 10 healthy subjects (25–31 years of age), lengthening of the R-R interval during squatting was abolished by atropine, whereas propranolol markedly attenuated shortening of the R-R interval at standing from squatting. Squatting test (SqT) ratios (SqT vagal [SqTv] = ratio between the R-R interval mean before squatting and the longest R-R interval after squatting; SqT sympathetic [SqTs] = ratio between the basal R-R interval and the shortest R-R interval at standing) were calculated in 558 healthy subjects and 346 diabetic patients (insulin-dependent diabetes mellitus/non-insulin-dependent diabetes mellitus: 103/243). Normal ranges (95 and 99% confidence intervals [CIs]) for subjects 20–74 years of age showed a statistically significant negative correlation with age. SqTv was outside the 99% CI in 145 (42%) diabetic patients and in 7 (1.3%) of the control subjects. The corresponding figures for SqTs were 40 and 0.8%, respectively. Age and duration of diabetes had a negative influence on SqT ratios. SqT ratios were compared with other reflex tests currently used for diagnosis of autonomic neuropathy: deep breathing (DB), lying-to-standing (LS), Valsalva manuever, and blood pressure change after standing (orthostatic hypotension [OH]). Autonomic involvement was arbitrarily defind as mild (one test pathologica), definite (two tests pathological), or severe (three or more tests pathological), definite (two tests pathological), or severe (three or more tests pathological). In patients with definite or severe involvement, Sqt ratios and DB anf LS tests showed the least overlap between healthy subjects and diabetic patients; however, for patients with mild or no autonomic involvement, SqT rations were significantly better than DB, LS, or OH tests. In conclusion, 1) SqT ratios can discriminate between healthy subjects and diabetic patients to an equal or greater extent than the other tests; 2) SqT ratios give information on both parasympathetic and sympathetic activity; and 3) SqT ratios are better than other single tests in identifying mild autonomic involvement. These results may be important for early intervention trials.
Atherosclerosis in Carotid Artery of Young IDDM Patients Monitored by Ultrasound High-Resolution B-Mode Imaging
Authors: Yamasaki Yoshimitsu , Kawamori Ryuzo , Matsushima Hiroyuki , Nishizawa Hideko , Kodama Mineo , Kajimoto Yoshitaka , Morishima Toyohiko , Kamada Takenobu
Published: September 2013

Ultrasound high-resolution B-mode imaging was used to assess the carotid arteries in 105 patients with insulin-dependent diabetes mellitus (IDDM), 4–25 years of age, with duration of diabetes ranging from 0.5–17 years, 529 patients with non-insulin-dependent diabetes (NIDDM), 31–86 years of age, with duration of diabetes ranging from 0.5–49 years, and 104 nondiabetic healthy subjects, 7–76 years of age, to determine the intimal plus medial thickness (IMT) of the arterial wall. The IMT values for IDDM patients 10–19 years of age (0.525 ± 0.123 mm, n = 68) or 20–25 years of age (0.696 ± 0.124 mm, n = 14) were significantly > those in age-matched nondiabetic subjects (0.444 ± 0.057 mm, n = 12, P = 0.01169; 0.538 ± 0.098 mm, n = 34, P < 0.00006). NIDDM patients showed IMT values equivalent to those in normal adults ≥ 20 years of age. Multiple regression analysis showed that IMT in IDDM patients was positively related to the duration of diabetes (P = 0.00061) as well as to age (P = 0.00046). No other possible risk factors, such as serum total cholesterol level, serum high-density lipoprotein (HDL)-cholesterol level, serum low-density lipoprotein-cholesterol level, serum triglycerides, serum lipoprotein(a) level, or systolic or diastolic blood pressure, have shown significant correlations with IMT in IDDM patients. However, non-HDL-cholesterol, smoking, and systolic hypertension were independently responsible for increases in IMT values of NIDDM patients as well as age and duration of diabetes. The partial regression coefficient of IMT for duration of diabetes (0.00978 mm/year) consistent with that of IMT for age (0.00848–0.00909 mm/year) in nondiabetic and diabetic subjects indicated that diabetes led to carotid atherosclerosis that was twice as advanced in children and adolescents with IDDM. Ultrasound high-resolution B-mode imaging revealed atherosclerosis in the carotid arteries of young IDDM patients on in vivo examination. Diabetes as well as aging can advance atherosclerosis in the carotid arteries of young diabetic patients. The IMT of carotid arteries, which can be measured noninvasively and frequently, may be an important indicator of atherosclerosis, even in young IDDM patients.
Genetic Predisposition to Diabetic Nephropathy: Evidence for a Role of the Angiotensin I–Converting Enzyme Gene
Authors: Doria Alessandro , Warram James H , Krolewski Andrzej S
Published: September 2013

In search of genetic determinants of susceptibility to diabetic nephropathy, we examined the association between DNA sequence differences at the locus of angiotensin I-converting enzyme (ACE) and renal complications in 151 insulin-dependent diabetes mellitus (IDDM) patients with a diabetes duration of 16–21 years. This nested case-control study included 77 normoalbuminuric control subjects (albumin excretion rate <30 μg/min) and 74 cases with evidence of nephropathy ranging from microalbuminuria to overt proteinuria. DNA from each of these patients was genotyped at the ACE locus by a three-allele restriction fragment-melting polymorphism (RFMP) (Dde I), which we described recently, and a two-allele insertion/deletion recognized as an Xba I restriction fragment-length polymorphism, which has been shown by other investigators to be associated with serum levels of ACE and with risk of myocardial infarction. The least common allele of the Dde I RFMP was significantly more frequent among cases with nephropathy than among normoalbuminuric control subjects (12.8 vs. 4.5%, P < 0.05). The deletion in the ACE gene was also more frequent in case than in control subjects (56.1 vs. 47.4%), but the difference was not statistically significant (P < 0.25) with this sample size. To determine the independence of these associations, the two polymorphisms were analyzed jointly to identify Xba I/Dde I haplotypes. As might be expected, carriers of the Xba I/Dde I ′+ =′ haplotype had a fourfold risk of developing diabetic nephropathy (odds ratio [OR] 4.0, 95% confidence interval [CI] 1.5–11.0). However, this did not explain all of the excess Xba I ′+′ allele among cases. Carriers of the ′++′ haplotype were also more frequent among cases (OR 2.0, 95% CI 0.8–4.9), but this association was not statistically significant with this sample size. This study provides evidence that DNA sequence differences in the ACE gene may contribute to genetic susceptibility to diabetic nephropathy in IDDM.
Mechanisms of the Stimulation of Insulin Release by Saturated Fatty Acids: A Study of Palmitate Effects in Mouse β-cells
Authors: Warnotte Catherine , Gilon Patrick , Nenquin Myriam , Henquin Jean-Claude
Published: September 2013

The mechanisms by which fatty acids increase insulin release are not known. In this study, mouse islets were used as a model and palmitate as a reference compound to study in vitro how saturated fatty acids influence pancreatic β-cells. Palmitate (625 μM) was bound to albumin. It did not affect basal insulin release (3 mM glucose) but increased the release induced by 10–15 mM glucose. This effect was dependent on the concentration of free rather than total palmitate. It was reversible and abolished by epinephrine, diazoxide, nimodipine, or omission of extracellular Ca. Bromopalmitate and methyl palmoxirate, two inhibitors of fatty acid oxidation, were ineffective alone, and only bromopalmitate partially inhibited the effects of palmitate on insulin release. The increase in insulin release produced by palmitate could not be ascribed to a blockade of ATP-sensitive K+-channels because the fatty acid only barely decreased 86Rb efflux and did not depolarize β-cells in 3 mM glucose. The small effect on 86Rb efflux might be attributed to a slight rise in the ATP/ADP ratio. No such rise occurred when palmitate was tested in 15 mM glucose, and the fatty acid consistently accelerated 86Rb efflux under these conditions. Measurements of β-cell membrane potential (intracellular microelectrodes) and of free cytoplasmic calcium (Cai 2+) in β-cells (Fura 2 technique) showed that palmitate increases Ca2+ influx; it also caused a very small mobilization of intracellular Ca. The persistence of this stimulation of Ca2+ influx in the presence of diazoxide and high K+ suggests that palmitate might act on Ca2+ channels. The rise in Ca12+ produced by palmitate was accompanied by an increase in insulin release only if the concentration of glucose was sufficiently high. The β-cell response to palmitate thus differs from the responses to glucose and other metabolized nutrients in several respects. Saturated fatty acids appear to potentiate insulin release through an increase in Ca12+ and another, yet unidentified, fuel-dependent mechanism.
Risk Factors for Cardiovascular Disease in IDDM: A Study of Identical Twins
Authors: Dubrey Simon W , Reaveley David R , Seed Mary , Lane David A , Ireland Helen , O'Donnell Martina , O'Connor Bernadette , Noble Mark I , Leslie R David G
Published: September 2013

Patients with insulin-dependent diabetes mellitus (IDDM) have an excess mortality, predominantly attributable to cardiovascular disease. To determine the effect of IDDM on potential risk factors for cardiovascular mortality, we studied subjects from the British Diabetic Twin Study Group. Forty-five identical twin pairs discordant for IDDM were recruited in addition to 45 matched nondiabetic singleton control subjects. All were selected to be normotensive and to have normal albumin excretion rates. Four variables differed significantly between the diabetic twins and their nondiabetic identical co-twins: diabetic twins had higher systolic blood pressure (sBP) ([mean ± SD] 127 ± 17 vs. 123 ± 18 mmHg, P < 0.05), high-density lipoprotein (HDL) cholesterol (1.36 ± 0.31 vs. 1.25 ± 0.29 mM, P < 0.05) and fibrinogen (3.23 ± 0.81 vs. 2.98 ± 0.71 mg/ml, P < 0.05) but lower factor VII (114 ± 34 vs. 122 ± 31%, P < 0.05). All four of these risk factors were significantly correlated (P < 0.001) within the identical twin pairs, as were the other risk factors. These significant correlations within twins for the risk factors studied reflects the impact of shared genetic and environmental influences. IDDM affects sBP, HDL cholesterol, fibrinogen, and factor VII, but only sBP and fibrinogen are affected adversely.
Physical Training Increases Muscle GLUT4 Protein and mRNA in Patients With NIDDM
Authors: Dela Flemming , Ploug Thorkil , Handberg Aase , Petersen Lone N , Larsen Jens J , Mikines Kári J , Galbo Henrik
Published: September 2013

Patients with non-insulin-dependent diabetes mellitus (NIDDM) exhibit insulin resistance and decreased glucose transport in skeletal muscle. Total content of muscle GLUT4 protein is not affected by NIDDM, whereas GLUT4 mRNA content is reported, variously, to be unaffected or increased. Physical training is recommended in the treatment of NIDDM, but the effect of training on muscle GLUT4 protein and mRNA content is unknown. To clarify the effect of training in NIDDM, seven men with NIDDM (58 ± 2 years of age [mean ± SE]) and eight healthy men (59 ± 1 years of age) (control group) performed one-legged ergometer bicycle training for 9 weeks, 6 days/week, 30 min/day. Biopsies were obtained from the vastus lateralis leg muscle before and after training. GLUT4 protein analyses was performed along with analyses of muscle biopsies from five young (23 ± 1 years of age) (young group), healthy subjects who participated in a previously published identical study. In response to training, maximal oxygen uptake increased (Δ 3.3 ± 1.8 in NIDDM subjects and 4.5 ± 1.2 ml.min−1·kg−1 in control subjects [both P < 0.05]). Before training, GLUT4 protein content was similar in NIDDM, control, and young subjects (0.35 ± 0.02, 0.34 ± 0.03, and 0.41 ± 0.03 arbitrary units, respectively), and it increased (P < 0.05) in all groups during training (to 0.43 ± 0.03, 0.40 ± 0.03, and 0.57 ± 0.08 arbitrary units, respectively). GLUT4 mRNA content was always lower in NIDDM compared with control subjects (P < 0.05) and increased in both groups (P < 0.05) during training (94 ± 6 to 122 ± 8 and 151 ± 5 to 170 ± 4 arbitrary units/10 μg total RNA, respectively). We conclude that muscle GLUT4 protein and mRNA increase in both NIDDM and control subjects in response to training. GLUT4 mRNA content is lower in NIDDM subjects compared with control subjects. GLUT4 protein content does not change with age.
The Relation of Diabetes to the Severity of Acute Myocardial Infarction and Post-Myocardial Infarction Survival in Mexican-Americans and Non-Hispanic Whites: The Corpus Christi Heart Project
Authors: Orlander Philip R , Goff David C , Morrissey Marilyn , Ramsey David J , Wear Mary L , Labarthe Darwin R , Nichaman Milton Z
Published: September 2013

The effect of diabetes on survival after myocardial infarction (MI) was examined in a prospective population-based study of individuals hospitalized with MI in a bi-ethnic community of Mexican-Americans and non-Hispanic whites. Among Mexican-Americans, 54% (331 of 610) had diabetes compared with 33% (192 of 589) of non-Hispanic whites (P < 0.001). Among those with diabetes, the prevalence of a history of a cardiac event before the index admission was significantly higher (odds ratio = 1.4, 95% confidence interval [CI] 1.1–1.8) than among nondiabetic subjects. During the index hospitalization, diabetic subjects received cardiac catheterization less frequently than did nondiabetic subjects (45.1 vs. 51.5%, P = 0.03). Diabetic subjects had lower estimated ejection fractions, and the number of coronary arteries with significant obstruction (> 75%) was higher (P < 0.001). The peak creatine phosphokinase and creatine phosphokinase myocardial isoenzyme (CK-MB) levels were similar in diabetic and nondiabetic subjects. Despite a similar infarct size, diabetic subjects had a higher incidence of congestive heart failure (relative ratio = 2.2, 95% CI 1.7–2.8), more adverse indexes of short-term and long-term prognosis, and a longer average hospital stay (12.1 vs. 8.9 days, P < 0.01). After adjustment for age, sex, and ethnicity, the cumulative risk for total mortality, over 44 months of follow-up, was 37.4% among diabetic compared with 23.3% among nondiabetic subjects (P < 0.001). Diabetic subjects had a higher 28-day case-fatality rate post-MI as well as higher long-term mortality. In conclusion, diabetic subjects have similar size infarcts compared with nondiabetic subjects, but they have a more complicated hospital course and higher total mortality post-MI. Diabetes had a similar adverse effect on post-MI mortality in both Mexican-Americans and non-Hispanic whites.
Effects of NIDDM on Lipoprotein(a) Concentration and Apolipoprotein(a) Size
Authors: Rainwater David L , MacCluer Jean W , Stern Michael P , VandeBerg John L , Haffner Steven M
Published: September 2013

We investigated the effects of non-insulin-dependent diabetes mellitus (NIDDM) on lipoprotein(a) (Lp[a]) and apolipoprotein(a) (apo[a]) in a population of Mexican-Americans. In plasma samples from 536 subjects, we measured Lp(a) concentrations, and we estimated apo(a) isoform sizes following immunostaining of plasma proteins resolved using sodium dodecyl sulfate electrophoresis. We identified 81 diabetic subjects who had 108 distinct apo(a) isoform bands. We then identified 81 nondiabetic subjects from the remainder who were closely matched for apo(a) phenotype (i.e., number and size of apo(a) isoform bands). As expected, the diabetic group had higher levels of glucose and insulin (both fasted and 2 h after glucose challenge) and triglycerides, and lower levels of high-density lipoprotein (HDL) cholesterol when compared with the matching nondiabetic group. Moreover, the diabetic group also had significantly lower Lp(a) concentrations than the nondiabetic subjects (10.6 vs. 13.6 mg/dl, P = 0.045) using a paired Student's t test. To detect the effects of diabetes on apo(a) size, we identified by pedigree analysis the nondiabetic family members who possessed alleles identical to those in the diabetic group. When we compared the average sizes for each allele, we found that apo(a) isoforms averaged 4.1 kDa larger in diabetic subjects than the genetically identical apo(a) measured in nondiabetic subjects (P = 0.044, n = 36 alleles). In summary, we have detected significant effects of NIDDM both on Lp(a) concentrations and on apo(a) size.
Reduced Plasma Peroxyl Radical Trapping Capacity and Increased Susceptibility of LDL to Oxidation In Poorly Controlled IDDM
Authors: Tsai Elaine C , Hirsch Irl B , Brunzell John D , Chait Alan
Published: September 2013

Oxidation of low-density lipoproteins (LDLs) has been postulated to play an important role in atherogenesis. Because oxidant stress may be increased and antioxidant defenses reduced in diabetes, the susceptibility of LDL to oxidative modification and total peroxyl radical trapping potential (TRAP) of plasma were evaluated in subjects with poorly controlled insulin-dependent diabetes mellitus (IDDM). The lag phase of conjugated diene formation after initiation of LDL oxidation by the addition of copper was shorter in diabetic subjects than in normal control subjects (126 ± 11 vs. 165 ± 15 min [means ± SE], P < 0.05). This could not be attributed to the presence of oxidation-susceptible, small, dense LDL particles in the diabetic subjects, whose lipoprotein particle distribution did not differ from the control subjects. However, the total TRAP of plasma, a measure of antioxidant defense, was reduced (626 ± 34 vs. 877 ± 41 μM, P < 0.0001) in diabetes. Of the plasma antioxidants measured, only uric acid and vitamin A were decreased in diabetes (P < 0.01), and both levels correlated with TRAP (r = 0.75, P < 0.001; r = 0.54, P < 0.001, respectively). The correlation between uric acid levels and TRAP persisted when the diabetes and control groups were analyzed separately. The reduced TRAP of plasma and the increased susceptibility of LDL to oxidative modification observed is consistent with a role for lipoprotein oxidation in the pathogenesis of atherosclerosis in IDDM.
Genetic Variants in Promoters and Coding Regions of the Muscle Glycogen Synthase and the Insulin-Responsive GLUT4 Genes in NIDDM
Authors: Bjørbæk Christian , Echwald Søren M , Hubricht Peter , Vestergaard Henrik , Hansen Torben , Zierath Juleen , Pedersen Oluf
Published: September 2013

To examine the hypothesis that variants in the regulatory or coding regions of the glycogen synthase (GS) and insulin-responsive glucose transporter (GLUT4) genes contribute to insulin-resistant glucose processing of muscle from non-insulin-dependent diabetes mellitus (NIDDM) patients, promoter regions and regions of importance for translation, as well as coding sequences of the two genes, were studied using single-strand conformation polymorphism (SSCP) analysis and DNA sequencing. The genetic analyses were performed in subgroups of 52 Caucasian NIDDM patients and 25 age-matched healthy volunteers. By applying inverse polymerase chain reaction and direct DNA sequencing, 532 base pairs (bp) of the GS promoter were identified and the transcriptional start site determined by primer extension. SSCP scanning of the promoter region detected five single nucleotide substitutions, positioned at 42, –16, –43, –143, and –250. The three most common variants could be excluded for having major impact on allele-specific GS mRNA expression in muscle. Scanning of GS cDNA revealed one frequent silent polymorphism at codon 342. Moreover, SSCP analysis of ∼900 bp of the promoter, the 5′-untranslated region, and the coding region of the GLUT4 gene showed four polymorphisms, all single nucleotide substitutions, positioned at –581, 1, 30, and 582. None of the three changes in the regulatory region of the gene had any major influence on expression of the GLUT4 gene in muscle. The variant at 582 in the GLUT4 cDNA was a silent polymorphism at codon 130. Southern blotting of both gene loci did not detect any major abnormalities. These findings, altogether, suggest that genetic abnormalities in the GS and GLUT4 genes are unlikely to be major contributors to the insulin-resistant glucose utilization in muscle among Caucasian NIDDM patients.
Autoimmune Diabetes Induced by the β-cell Toxin STZ: Immunity to the 60-kDa Heat Shock Protein and to Insulin
Authors: Elias Dana , Prigozin Haia , Polak Natalie , Rapoport Micha , Lohse Ansgar W , Cohen Irun R
Published: September 2013

Administered at a suitably low dose, the toxin streptozotocin (STZ) can trigger an autoimmune process leading to destruction of the β-cells of the pancreatic islets. In this study, we examined specific immunological reactions in mice before and during the development of STZ-induced autoimmune diabetes. We now report that the development of spontaneous autoantibodies to insulin can serve as a marker of susceptibility to a low dose of STZ. Susceptible male mice of the C57BL/KsJ strain manifested such anti-insulin antibodies, and resistant female mice did not. Administration of a low dose of STZ (five daily doses each of 30 mg/kg) induced transient hyperglycemia ∼20–30 days later, which temporarily remitted but was followed by intractable diabetes ∼2.5 months later. The diabetogenic process triggered by the low dose of STZ was associated with an increase in the level of anti-insulin antibodies bearing the Dana and Micha (DM) idiotype, later followed by the appearance of anti-idiotypic antibodies that peaked before the onset of diabetes. Antibodies and T-cells reactive to hsp60 (heat shock protein) were triggered by the low-dose STZ administration and persisted throughout the period that preceded clinical diabetes. T-cells reactive to the p277 peptide of hsp60 were also observed. Finally, active immunization to hsp60 caused transient hyperglycemia by itself and also aggravated the hyperglycemia induced by low-dose STZ. Thus, autoantibodies to insulin can indicate susceptibility to a toxic trigger of diabetes, and a low dose of a toxin can activate the insulin and hsp60 autoimmunity that has been detected previously in the spontaneous autoimmune diabetes of NOD strain mice.
Evidence That Glucose Increases Monocyte Binding to Human Aortic Endothelial Cells
Authors: Kim Jeong A , Berliner Judith A , Natarajan Rama D , Nadler Jerry L
Published: September 2013

The rate of atherosclerosis is accelerated in humans with diabetes. The adhesion of monocytes to the vascular endothelium is a key event in the development of atherosclerosis. Alloxan (ALX)-induced diabetes in rabbits causes leukocyte accumulation on the arterial surface. However, the effect of glucose exposure on monocyte binding is not understood. We evaluated the effect of chronic elevated glucose on human monocyte binding to human aortic endothelial cells (HAEC) in culture. Monocyte binding to HAEC was significantly increased by chronic incubation of HAEC in high glucose for 7–10 days (CH-HG; 25 mM) compared with cells cultured for the same time in normal glucose (5.5 mM; CH-HG, 188 ± 10 cells/field vs. normal glucose, 111 ± 7; P < 0.0005). Use of mannitol at a concentration to stimulate the hyperosmolar effects of glucose did not significantly alter monocyte binding. Acute 20-min exposure of HAEC to high glucose did not alter monocyte binding. The adherence of HL-60 cells, a neutrophil-like cell line, or human neutrophils was not induced by CH-HG culture. High glucose–induced monocyte binding was not associated with induction of the major endothelial cell adhesion molecules, including E-selectin, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 (ICAM-1). A monoclonal antibody TS1–18 to the β2 integrin component that is involved in binding to ICAM-1 on endothelial cells significantly reduced monocyte binding, whereas anti-VLA-4 antibody was not effective. These results suggest that hyperglycemia can accelerate the rate of atherosclerosis in diabetics by increasing monocyte binding to the endothelium.