bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosynthesis of Proinsulin and Other Islet Cell Proteins in Pancreatic Beta Cells of the Rat: A Radioautographic Evaluation of Glucose Effects In Vitro
Authors: Logothetopoulos John , Jain Kanti
Published: September 2013

Rat pancreatic islets were incubated in vitro with L-[4,5-3H]leucine or with L-[2,3-3H]tryptophan in Krebs-Ringer bicarbonate buffer, containing 0, 5, or 20 mM glucose. Incorporation of labeled amino acids in islet cells was evaluated quantitatively by a validated radioautographic procedure. Incorporation of labeled leucine into [3H]proinsulin and [3H]insulin was measured by immunoprecipitation and into other islet proteins by trichloroacetic acid precipitation.

Incorporation of labeled amino acids in pancreatic beta cells was patchy and not uniform. Up to 20 to 35% of beta cells, mainly in central regions of the islets, showed poor or no incorporation of label. Peripheral nonbeta, endocrine islet cells and mesenchymal islet cells were all uniformly labeled. Incorporation of either amino acid into nonbeta endocrine and mesenchymal cells was not much affected by the absence of glucose in the incubation buffer. In contrast, incorporation of the amino acids into beta cells was strikingly affected. Incorporation of [3H]leucine into proinsulin and insulin at 0 mM glucose measured by specific immunoprecipitation and by silver grain densities over beta cells was 15 to 20 times less than at 20 mM glucose. Incorporation of [3H]tryptophan, an amino acid absent in proinsulin, into nonhormonal, sedentary beta cell proteins studied by radioautography, similarly, was strikingly affected in the absence of glucose. Thus, radioautography revealed a great sensitivity of both hormonal and nonhormonal protein biosynthesis in the beta cell to the concentration of glucose in the medium.
Insulin Stimulation of Glycogen Synthase in Cultured Human Diploid Fibroblasts
Authors: Hidaka Hideki , Howard Barbara V , Kosmakos Frank C , Fields Rose M , Craig James W , Bennett Peter H , Larner Joseph
Published: September 2013

The effect of insulin on glycogen synthase activity in human diploid fibroblasts has been studied. As little as 2 × 10−10 M insulin increased the glycogen synthase / activity without changing the total activity. Stimulation occurred within 5 minand became maximal in 30 min. A half-maximal increase of / activity was achieved at 3 × 10−9 M insulin. Glucose starvation increased the magnitude of response of glycogen synthase to insulin but did not change the insulin concentration necessary to give a half-maximal stimulation. Glucose increased the basal level of / activity in human diploid fibroblasts; the effect of insulin was additive. During in vitro senescence the total glycogen synthase activity declined, but the concentration of insulin that produced a half-maximal stimulation remained unchanged. These data indicate that regulation of glycogen synthase activity in human diploid fibroblasts is responsive to physiologic insulin levels and that the system provides a useful model for the in vitro study of insulin sensitivity.
Decreased Insulin Binding of Human Erythrocytes After Dexamethasone or Prednisone Ingestion
Authors: Yasuda Keigo , Kitabchi Abbas E
Published: September 2013

We have investigated changes in insulin binding in erythrocytes in response to overnight ingestion of 1 mg dexamethasone or 10 mg of prednisone in two groups of eight lean, healthy subjects. Dexamethasone administration reduced insulin binding from 9.6 to 6.8% (P <0.001) with concomitant increase in basal plasma insulin from 10.5 to 14.1 μU/ml (P <0.05). Prednisone ingestion reduced insulin binding from 9.9 to 7.9% (P <0.01), but the increase in basal insulin from 16.9 to 20.6 μU/ml was not significantly different. The decrease in insulin binding with both dexamethasone and prednisone was associated with decreased affinity of erythrocyte for insulin at low occupancy and the increase in the dose of unlabeled insulin resulted in 50% inhibition of specific binding without changes in the number of receptors. The earliest decrease in insulin binding was noted within 2 h after ingestion of 1 mg of dexamethasone. These data suggest that acute alteration of insulin receptor function could occur in erythrocytes by small amounts of dexamethasone or prednisone through a mechanism consistent with a decrease in receptor affinity rather than a decrease in the number of receptors.
Insulin Receptors and Protein Synthesis in Bone Marrow Cells and Reticulocytes
Authors: Thomopoulos Pierre , Testa Ugo , Flamier Aline , Berthelier Martine
Published: September 2013

Normal rabbit bone marrow erythroid cells have been found to possess insulin receptors. Their number shows an inverse relationship with the stage of differentiation, ranging from 20,000 sites/cell in the less mature to 8,000 sites/cell in the more mature cells. In addition, insulin rapidly stimulates the incorporation of leucine into protein in these cells and in rabbit, human, and rat peripheral blood reticulocytes. In rat reticulocytes, the concentration range of the hormone required for this phenomenon is from 25 to 625 μU/ml.
Modalities of Gliclazide-induced Ca2+ Influx into the Pancreatic B-Cell
Authors: Lebrun P , Malaisse W J , Herchuelz A
Published: September 2013

The hypoglycemic sulfonylurea gliclazide stimulated 45Ca efflux and insulin release from prelabeled and perifused pancreatic rat islets, whether in the absence or presence of glucose (8.3 mM). The gliclazideinduced increase in 45Ca efflux is thought to reflect a stimulation of 40Ca influx into islet cells; it is suppressed in the absence of extracellular Ca2+ or in the presence of the organic Ca2+ -antagonist verapamil. In the absence of glucose, the ED50 for the inhibitory action of verapamil on gliclazide-stimulated 45Ca efflux was.almost identical to that found when the process of 40Ca-45Ca exchange was stimulated by an increase in the extracellular concentration of K+, a procedure that leads to the depolarization of the plasma membrane. .In the presence of glucose, however, the cationic response to gliclazide displayed an increased sensitivity toward the inhibitory action of verapamil. It is proposed that hypoglycemic sulfonylureas facilitate Ca2+ inflow into islet cells mainly through voltage-sensitive Ca2+ channels. In the presence of glucose, however, the stimulant action of hypoglycemic sulfonylureas upon Ca2+ entry into islet cells may entail a modality of Ca2+ transport not identical to that evoked by depolarization of the plasma membrane.
Glucose-induced Thermogenesis in Nondiabetic and Diabetic Obese Subjects
Authors: Golay A , Schutz Y , Meyer H U , Thiébaud D , Curchod B , Maeder E , Felber J-P , Jéquier E
Published: September 2013

The glucose-induced thermogenesis (GIT) following a 100-g oral glucose load has been measured by continuous indirect calorimetry in 55 nondiabetic and diabetic obese subjects of various ages and compared with two control groups of 17 young and 13 elderly nonobese subjects. The obese subjects were divided into four groups: group A, normal glucose tolerance; group B, impaired glucose tolerance; group C, diabetes with increased insulin response; group D, diabetes with reduced insulin response.

The glucose-induced thermogenesis measured during 3 h represented 8.6 ± 0.7% of the energy content of the load in the young control group. In all obese groups, the glucose-induced thermogenesis was significantly lower than in the young control group, i.e., 6.6 ± 0.9%, 6.4 ± 0.6%, 3.7 ± 0.7%, and 2.2 ± 0.4% in groups A, B, C, and D, respectively. Since the obese diabetics were older than the other groups, their glucose-induced thermogenesis was compared with that of the elderly control group; the latter (5.8 ± 0.3%) was significantly lower (P < 0.05) than that of the young control group. The obese diabetics also had a significantly lower glucose-induced thermogenesis than the elderly control group (P < 0.02 and P < 0.001 for groups C and D, respectively). When corrected for glucosuria and after taking into account the glucosuria and the changes in the glucose space, the corrected glucose-induced thermogenesis (i.e., related to glucose “uptake”), was still significantly reduced in group A versus the young control group (6.6 ± 0.9 versus 8.6 ± 0.7%, P < 0.05), and in group D versus the elderly (matched for age) control group (4.2 ± 0.7 versus 5.8 ± 0.3%, P < 0.05).

It is concluded that the postprandial thermogenesis induced by glucose ingestion is decreased in the presence of insulin resistance and/or reduced insulin response to the glucose load in obese subjects. In addition, age itself contributes to decrease glucose-induced thermogenesis.
Preparation of Rat Islet B-Cell-Enriched Fractions by Light-Scatter Flow Cytometry
Authors: Rabinovitch Alexander , Russell Thomas , Shienvold Frances , Noel Jack , Files Nancye , Patel Yogesh , Ingram Marylou
Published: September 2013

Flow cytometry has been examined as a method to separate islet cells into homogeneous subpopulations. Collagenase-isolated rat islets were dissociated into single cells and these were analyzed and sorted according to their low forward angle light scattering properties by using automated flow cytometry. Light scatter histograms showed two peaks of viable cells. Radioimmunoassay of hormone content in cell fractions collected across the two peaks showed that glucagon- containing cells were concentrated towards the left side of the left peak and somatostatin-containing cells were concentrated towards the right side of the left peak, whereas insulin-containing cells were clearly enriched in the right peak. The B-cell-enriched fraction (90% B cells, 3% A cells, 2% D cells) exhibited significant insulin secretory responses to glucose (16.7 mM), and 3-isobutyl-1-methylxanthine (0.1 mM), during a 24-h culture period, and these responses were slightly greater than those observed in the original mixed islet cell preparation (66% B cells, 14% A cells, and 4% D cells). These results indicate that flow cytometry can be applied to sort pancreatic islet cells into populations enriched in specific endocrine cell types for further study of the functions of individual cell types.
Insulin and Glucagon Release from Cultured Neonatal Pancreatic Islets of Lean and Preobese Zucker Rats
Authors: Hayek Alberto
Published: September 2013

Pancreatic islets were isolated from individual neonatal (2-5 days of age) lean and preobese Zucker rats to assess insulin and glucagon release after 7 and 14 days of culture. Insulin and glucagon release were elicited with high glucose (22.2 mM) plus aminophylline (10 mM) and alanine (10 mM), respectively.

The similar secretory hormone patterns, both at basal and stimulated conditions, of the islets from rats later identified as lean or obese, suggest that a primary islet defect does not cause the hyperinsulinemia.
Increased In Vivo Insulin Resistance in Nondiabetic Pima Indians Compared with Caucasians
Authors: Nagulesparan Murugasu , Savage Peter J , Knowler William C , Johnson Ginger C , Bennett Peter H
Published: September 2013

Pima Indian adults have the highest reported prevalence of non-insulin-dependent (type II) diabetes mellitus and an extraordinary prevalence of obesity. Before development of fasting hyperglycemia, insulin concentrations in the Pimas are elevated both during fasting and after a glucose challenge, suggesting resistance to insulin action. To determine if Pima hyperinsulinemia is associated with resistance to insulin- mediated glucose disposal and if there are racial differences in insulin resistance not attributable to obesity, insulin resistance and the plasma insulin response to oral glucose were measured in Pima Indians and Caucasians with normal glucose tolerance and varying degrees of obesity. Fasting insulin concentrations, adjusted for obesity, age, and sex, were similar in both groups, and similar relationships were found in the Pima and Caucasian subjects between obesity, fasting insulin levels, and the insulin response to oral glucose. Resistance to exogenous insulin was measured by the steady-state plasma glucose (SSPG) technique, where a mixture of insulin, glucose, and somatostatin is infused, and the plasma glucose concentration attained is taken as a measure of insulin resistance. SSPG concentrations in both Pimas and Caucasians correlated significantly with obesity and with the fasting insulin concentrations. SSPG levels were significantly higher in the Pimas (P < 0.01) and remained so even after adjustment for obesity, age, and sex (35 ± 1 2 mg/dl higher in Pimas than in Caucasians, P < 0.01), indicating that hyperinsulinemia in the Pimas reflects a resistance to insulin action and that a greater degree of insulin resistance occurs in nondiabetic Pimas than in similarly obese Caucasians. This resistance to insulin-mediated glucose metabolism may contribute to the high incidence of diabetes in the Pima Indian population.
On the Mechanisms of Inhibition of Insulin Action by Small-Molecular-Weight Trypsin Inhibitors
Authors: Muchmore Douglas B , Raess Beat U , Bergstrom Richard W , de Haën Christoph
Published: September 2013

Evidence from a number of laboratories has suggested that the mechanism of insulin action involves the release of an intracellular mediator polypeptide from the plasma membrane. It has been proposed that activation of a protease with trypsin-like specificity is involved in release of the putative mediator. In an effort to assess the potential role of such a protease in intact cells, the present study tested the effects of a variety of low-mol-wt protease inhibitors on insulin's metabolic action in isolated rat epididymal fat cells. The protease inhibitors studied included paminobenzamidine, benzamidine, phenylguanidine, diisopropylflubrophosphate, leupeptin, and the competitive substrate N-α-tosyl-L-arginine methylester. Leupeptin was devoid of activity. Most of the other inhibitors used were able to interfere with insulin-stimulated metabolism if used in sufficiently high concentrations, concentrations considerably higher than those required for inhibition of known proteases or inhibition of intracellular processes in a previously described system which involves a trypsin-like enzyme. Moreover, they displayed various activities unrelated to protease inhibition that could explain their effects on insulin action better than protease inhibition. While none of the data on individual inhibitors were by themselves convincing enough to either confirm or reject the hypothesis concerning the involvement of a protease with trypsin-like specificity in insulin action, taken together our results do weaken the hypothesis considerably and in particular render the involvement of an extracellular trypsin-like enzyme improbable.
Lens Capsule Basement Membrane Synthesis: Stimulation by Glucose In Vitro
Authors: Cohen Margo Panush , Ciborowski C James , Surma Maria L
Published: September 2013

To examine the question of whether hyperglycemia per se can affect basement membrane synthesis, intact rat lenses, which produce basement membrane in vitro, were incubated for 24 h with radioactive proline or lysine and varying concentrations of glucose. Lens capsule basement membrane (LCBM) was subsequently purified and analyzed for radiolabel incorporation and for specific activities of proline, hydroxyproline, lysine, and hydroxylysine. [14C]-proline and lysine incorporation into LCBM was increasingly stimulated in incubations performed with 10 and 20 mM compared with 5 mM glucose. High glucose concentration increased the specific activity of proline and lysine but not hydroxyproline or hydroxylysine, and decreased the ratio of radioactive hydroxyproline to proline. Gel electrophoresis of radiolabeled LCBM prepared after high glucose incubation revealed increased radioactivity in several high-molecular-weight components corresponding with the major Coomassie-blue peptide bands. The results indicate that glucose stimulates LCBM synthesis, and suggest that this effect derives from increased production of noncollagenous components.
Pregnancy-associated Hypertriglyceridemia in Normal and Diabetic Women: Differences in Insulin-dependent, Non-insulin-dependent, and Gestational Diabetes
Authors: Hollingsworth Dorothy R , Grundy Scott M
Published: September 2013

In this study longitudinal observations of plasma lipo-proteins were made in pregnant diabetic women classified according to the National Diabetes Data Group. Sequential measurements at second trimester (25–27 wk), third trimester (34–37 wk), and 3 mo postpartum (control period) were carried out in 18 diabetic and 6 normal women. In 15 diabetic and 4 normal women from this group, 24-h plasma glucose, serum C-peptide levels, and HbA1c concentrations were measured. Another group of 15 normal and 18 diabetic women underwent determinations of fasting plasma lipoproteine and other parameters at one or more of the test periods.

Insulin-dependent diabetic patients (IDDM, type I) as a group did not differ from normal controls in mean plasma levels of total cholesterol (CHOL), triglyceride (TG), very-low-density lipoprotein triglyceride (VLDL TG), low-density lipoprotein cholesterol (LDL CHOL), high-density lipoprotein cholesterol (HDL CHOL), or ratios of TG:CHOL in LDL or HDL during mid or late pregnancy or 3 mo postpartum. In marked contrast, non-insulin-dependent diabetics (NIDDM, type II) had significantly higher total fasting TG at second trimester (P < 0.005), third trimester (P < 0.03), and postpartum (P < 0.01). VLDL TG levels at the second trimester, third trimester, and postpartum also were higher than in women with IDDM or normals. In NIDDM subjects the accentuated hypertriglyceridemia during second and third trimesters was also apparent in elevated LDL TG:CHOL and HDL TG:CHOL ratios. These differences were not correlated with prepregnancy weight, weight gain during gestation, or diabetic control. Women with gestational diabetes (GDM) also had significantly higher TG levels at second trimester and postpartum. Mean HDL CHOL levels were significantly lower in patients with NIDDM and GDM than in controls and IDDM patients throughout pregnancy and 3 mo postpartum. Two of 21 normals and one woman with IDDM diabetes had spontaneously reversible pregnancy-evoked hypertriglyceridemia.

These results indicate that women with IDDM diabetes do not differ from normal women with respect to pregnancy-associated changes in lipid metabolism. On the other hand, women with NIDDM and GDM exhibit a pregnancy-associated hypertriglyceridemia.
Inhibition of In Vitro Lymphocyte Response by Streptozotocin-induced Diabetic Rat Serum: A Function of Very-Low-Density Lipoproteins
Authors: Chi David S , Berry Dianne L , Dillon Karen A , Arbogast Bradley W
Published: September 2013

Immune function is generally reported to be impaired in uncontrolled diabetes mellitus. We have previously reported that very-low-density lipoproteins (VLDL) from diabetic rat serum injure endothelial cells in vitro. Thus, we wanted to determine if VLDL would also injure lymphocytes and impair the immunity of the streptozotocin-induced diabetic rat. The immunologie functions of spleen cells from normal and diabetic rats were studied using the in vitro mitogenic stimulation assay and mixed lymphocyte responses (MLR). The effects of diabetic serum and VLDL isolated from diabetic rat serum on normal spleen cells were also determined. Both the absolute peripheral blood leukocyte (PBL) and spleen cell numbers of diabetic rats were significantly decreased from those of normal rats (P < 0.02). In PBL there was a decreased percentage of lymphocytes and increased percentage of neutrophils (both P < 0.02). The mitogenic stimulation responses of spleen cells from diabetic rats were consistently lower than normal for 3 of the 4 mi-togens used. The responses of con A-stimulated lymphocytes from diabetic spleens were significantly different (P < 0.025) from normal spleen cells. The MLR appeared to be normal. The decreased mitogenic responses of cells from diabetic spleens were not due to the induction of suppressor cells. Diabetic rat serum inhibited the proliferation of both control and mitogen-stimulated normal rat lymphocytes. Addition of increasing amounts of VLDL, isolated from diabetic serum, to normal spleen cell cultures also resulted in an exponential decrease in 3H-thymidine incorporation. Complete inhibition of the response of normal spleen cells to PHA was achieved at a VLDL triglyceride concentration of 262 μg/ml. The 4-day-old lym-phyocyte cultures incubated with VLDL at 262-μg/ml concentration were only 11% viable, which was significantly lower than the 58% viability of control cultures without VLDL (P < 0.005). Removal of VLDL from diabetic rat serum eliminated the toxic effect of diabetic serum on spleen cell cultures. Reconstitution of the infra nata n t fraction (d > 1.006) with the VLDL fraction (d < 1.006) restored the toxic activity. These results indicate that the inhibitory effect of diabetic rat serum on the mitogenic responses of normal rat spleen cells is due to the toxicity Of VLDL.
Correlations of Hemoglobin A1c and Metabolic Status in Nondiabetic, Borderline Diabetic, and Diabetic Macaca Nigra
Authors: Howard Charles F
Published: September 2013

Glycosylated hemoglobin A1c (HbA1c) increases from 2.6% in nondiabetic Macaca nigra to 7.9% in diabetic monkeys. Monkeys without overt hyperglycemia but with impaired glucose clearance, impaired insulin secretion, and increased postprandial glucose have a significant increase in glycosylation to 3.5% HbA1c. Two different forms of hemoglobin are electrophoretically distinguishable in this species due to an amino acid change in the globin beta-chain. Colorimetrie analysis established that glycosylation of the different hemoglobin forms was related only to metabolic status. Percentages of glycosylated hemoglobins indicate the inability of monkeys with varying severity of metabolic abnormalities to adequately maintain glucose homeostasis.
A Mechanism of Susceptibility to Mucormycosis in Diabetic Ketoacidosis Transferrin and Iron Availability
Authors: Artis William M , Fountain John A , Delcher Harry K , Jones Henry E
Published: September 2013

The defect in host defense that makes the diabetic ketoacidotic (DKA) patient susceptible to mucormycosis has not been identified. Sera from 10 DKA patients and three normal volunteers were tested for their capacity to support the in vitro growth of a common etiologie agent of mucormycosis, Rhizopus oryzae. After equilibration with room air none of the normal or DKA sera, each of which was now extremely alkaline, supported growth of R. oryzae. When the sera were placed in a CO2 atmosphere that permitted simulation of the in vivo clinical pH (normal 7.40 and DKA 7.3–6.6), four of seven DKA sera supported profuse fungal growth. No growth occurred in normal serum. The three DKA sera that did not support fungal growth at pH ≤7.3 contained less iron (× = 13 μg/dl) than the four sera that supported profuse fungal growth (× = 69 μg/dl). Increasing the iron content of iron-poor DKA serum that did not support R. oryzae growth allowed profuse growth at acidotic conditions but not at pH ≥7.4. Simulated acidotic conditions (pH 7.3–6.6) also decreased the iron-binding capacity of normal serum stepwise from 266 μg/dl to 0. Our data indicate that acidosis temporarily disrupts the capacity of transferrin to bind iron and suggest that this alteration abolishes an important host defense mechanism that permits growth of R. oryzae.
ε-Amino-Lysine-Bound Glucose in Human Tissues Obtained at Autopsy: Increase in Diabetes Mellitus
Authors: Vogt B W , Schleicher E D , Wieland O H
Published: September 2013

The level of nonenzymatically ε-lysine-bound glucose (NEBG) of tissue proteins obtained at autopsy has been determined with a specific method recently described.5 The mean values expressed as nmol lysine-bound glucose per μmol phenylalanine were 34 for tendon, 13 for aorta, 16 for coronary artery, 23.5 for femoral nerve, 10 for glomerular basement membrane, and 30 for lung parenchyma for tissues from nondia-betics and 86, 39.5, 34, 60, 29, and 57 for tissues from diabetics, respectively. NEBG was below detection limit in skeletal muscle from either nondiabetic or diabetic subjects. Tendon and aorta NEBG levels correlated well with those from other tissues (r = 0.8=0.94, except r = 0.68 for glomerular basement membrane). A fairly good correlation was also found when NEBG of aorta was compared with the mean blood sugar level determined during the last weeks of hospitalization. Finally, an arbitrary index of diabetic late complication was compared with NEBG of aorta. There appears to be a tendency of an increase of the index of complications along with an increase in tissue glucosylation. The possible role of nonenzymatic glucosylation in the long-term complication of diabetes is discussed.
Absence of Angiogenesis-lnhibitory Activity in Aqueous Humor of Diabetic Rabbits
Authors: Okamoto Taira , Oikawa Shinichi , Toyota Takayoshi
Published: September 2013

We studied inhibitory activity of angiogenesis in the eye to explore the formation of new blood vessels in diabetic microvascular diseases. When we examined the effects of extracts from various ocular tissues of nondiabetic rabbits on the proliferation of bovine aortic endothelial cells, potent inhibitory activity was found in lens and aqueous humor. Aqueous humor inhibited both angiogenesis on chorioallantoic membrane in vivo and promotion of endothelial cell growth in vitro, which were induced by retinal extracts. However, in diabetic rabbits, aqueous humor lost the ability to inhibit the growth of endothelial cells. The loss of activity became evident 1 mo after the alloxan injection and lasted while the animals were hyperglycemic. In addition, diabetic aqueous humor failed to suppress retinal extract-induced angiogenesis promotion and endothelial cell growth. The absence of the inhibitory activity of angiogenesis in diabetic aqueous humor might be involved in promotion of neovascularization in diabetic ocular disease.
Absence of Brown Product FFI in Nondiabetic and Diabetic Rat Collagen
Authors: Lapolla Annunziata , Gerhardinger Chiara , Pelli Beatrice , Sturaro Alberto , Favero Elio Del , Traldi Piero , Crepaldi Gaetano , Fedele Domenico
Published: September 2013

Accumulation of brown products in long-lived proteins might be an important factor in determining long-term diabetic complications. Fluorescent chromophore 2-(2-furoyl)-4-(5)-(2-furanyl)-1H-imidazole (FFI), isolated from hydrolyzed brown products synthesized in vitro, was proposed as a specific brown product responsible for functional and structural changes in long-lived proteins. In this study, an attempt was made to demonstrate by means of collision spectroscopy the presence of FFI in collagen samples taken from diabetic rats. Diabetic rat collagen samples showed mean values of absorbance per milligram of 4-hydroxy-L-proline significantly higher than those observed in nondiabetic rats, suggesting higher FFI levels. Surprisingly, all collagen samples from diabetic and nondiabetic rats gave collision spectra in which no peak diagnostic of FFI presence was observed. These data suggest that the absorbance level observed in diabetic rats is not due to the presence of FFI but to structurally related compounds, which are being investigated by means of mass spectrometry.
Adenosine Reversal of In Vivo Hepatic Responsiveness to Insulin
Authors: McLane Michael P , Black Preston R , Law William R , Raymond Richard M
Published: September 2013

Modulation by adenosine of hepatic responsiveness to insulin was investigated in vivo in 10 healthy mongrel dogs of both sexes by determining net hepatic glucose output (NHGO) in response to insulin during the presence or absence of exogenous adenosine infusion. In addition, two separate series of experiments were performed to study the effect of adenosine (n = 7) or glucagon (n = 5) on NHGO. Basal NHGO, quantitated via the Fick principle, was significantly decreased by insulin infusion (4 U/min; 4.8 ± 0.6 vs. −1.7 ± 2.6 mg · kg−1 · min−1, P < 0.05). The addition of an intrahepatic arterial infusion of adenosine (10 μmol/min) during insulin infusion caused glucose output to return to basal levels (insulin, −1.7 ± 2.6 mg · kg−1 · min−1; insulin + adenosine, 3.8 ± 1.6 mg · kg−1 · min−1, P < 0.05). The addition of intrahepatic arterial saline (control) during insulin infusion had no effect on insulin's action (insulin, −1.0 ± 1.9 mg · kg−1 · min−1; insulin + saline, −1.2 ± 1.6 mg · kg−1 · min−1, P > 0.05). Hepatic glucose, lactate, and oxygen deliveries were not affected during either insulin or insulin plus adenosine infusion. Intrahepatic arterial infusion of adenosine alone had no effect on NHGO, whereas intrahepatic arterial infusion of glucagon alone stimulated glucose output approximately fivefold (basal, 2.7 ± 0.4 mg · kg−1 · min−1; glucagon, 15.5 ± 1.2 mg · kg−1 · min−1, P < 0.01). These results show that adenosine completely reversed the inhibition by insulin of NHGO. These data suggest that adenosine may act as a modulator of insulin action on the liver.
Effects of Converting-Enzyme Inhibition on Barrier Function in Diabetic Glomerulopathy
Authors: Morelli Ester , Loon Nicholas , Meyer Timothy , Peters William , Myers Bryan D
Published: September 2013

Differential solute clearances were used to examine the effects of a 90-day course of enalapril on glomerular barrier function in 16 proteinuric patients with diabetic glomerulopathy. By day 90, plasma renin and prorenin became elevated, and arterial pressure declined. Transglomerular passage of dextrans of broad size distribution (radii 28–60 Å) was lowered significantly. In a subset of 8 patients, withdrawal of enalapril was followed after an additional 30 days by a return of renin levels and arterial pressure to pretreatment levels. The dextran-sieving profile also returned to baseline, becoming uniformly elevated above treated day-90 levels. A theoretical analysis of the serial dextran-sieving profiles indicated that enalapril shifted glomerular pore size distribution to smaller size. These changes in barrier size selectivity were associated with a reduction in fractional albumin and IgG clearances during enalapril therapy and a subsequent rise in these quantities after its withdrawal; urinary protein excretion rate tended to vary in parallel. We conclude that inhibition of converting enzyme in humans with established diabetic glomerulopathy diminishes glomerular permeability to proteins by enhancing barrier size selectivity. Because neither enalapril therapy nor its withdrawal influenced the glomerular filtration or renal plasma flow rates significantly, we propose that the primary action of enalapril may be to modulate the intrinsic membrane properties of the glomerular barrier.
Role of Glutamine as a Glucose Precursor in Fasting Humans
Authors: Hankard Régis G , Haymond Morey W , Darmaun Dominique
Published: September 2013

Recently, significant incorporation of labeled carbon into plasma glucose was documented during infusion of 14C-labeled glutamine in postabsorptive humans. Such labeling of plasma glucose can occur as a result of two different processes: either 1) through incorporation of glutamine carbon into glucose via glutamine entering Krebs cycle at a-ketoglutarate or 2) through simple fixation of labeled CO2 resulting from oxidation of labeled glutamine. Therefore, these studies were designed to determine 1) whether glutamine contributes carbon to gluconeogenesis other than through mere CO2 fixation, and, if so, 2) whether the apparent transfer of carbon from glutamine to glucose increases with fasting. Eight healthy adults were studied on two consecutive days: once after an overnight (18-h) fast and again on the second day of fasting (42-h fast). On each study day, subjects received a simultaneous 5-h infusion of D-[6,6-2H2]glucose, l-[3,4-13C2]glutamine, and l-[l-14C]leucine. Apparent rates of incorporation of glutamine carbon into glucose were estimated from the appearance of 13C into plasma glucose; glucose and glutamine production rates (appearance rate [-RJ) were determined from plasma [2H2]glucose and [13C2]glutamine enrichments, respectively. The appearance of 14C into plasma glucose was used to correct the measured rates of carbon transfer from glutamine to glucose as a result of CO2 fixation. We observed that of the apparent contribution of labeled glutamine to gluconeogenesis, only 4% occurred as a result of fixation of labeled CO2, while 96% seemed to occur through other routes. We also observed that between 18 and 42 h of fasting, 1) the relative contribution of protein breakdown to glutamine production was enhanced, while that of de novo synthesis declined; 2) the apparent contribution of glutamine to glucose production rose from 8 ± 1 to 16 ± 3% of overall glucose Ra; and 3) the relative apparent contribution of glutamine to gluconeogenesis remained constant. From the current data, it cannot be ascertained to what extent the apparent carbon transfer from glutamine to glucose represents a true contribution of glutamine to gluconeogenesis or mere carbon exchange between the trichloroacetic acid cycle and the gluconeogenic pathway. These findings are nevertheless compatible with a role of glutamine as a significant precursor of glucose in fasting humans.
High-Dose Intravenous Insulin Infusion Versus Intensive Insulin Treatment in Newly Diagnosed IDDM
Authors: Schnell Oliver , Eisfelder Bastian , Standl Eberhard , Ziegler Anette-Gabriele
Published: September 2013

High-dose intravenous insulin infusion at the onset of IDDM has been suggested to improve β-cell function during the 1st year of insulin treatment. To test this hypothesis, we randomly assigned newly diagnosed IDDM patients to receive either an experimental 2-week high-dose intravenous insulin infusion (n = 9; age, 25 ± 7 years; HbA1c, 10.5 ± 2.0%) or an intensive insulin therapy of four injections per day (n = 10; age, 28 ± 7 years; HbA1c, 12.3 ± 3.0%). The experimental-therapy group received three times more insulin (1.2 ± 0.4 U · kg−1 · day−1) than the intensive-therapy group (0.4 ± 0.1 U · kg−1 · day−1, P < 0.0005). By week 3, both groups were treated similarly with intensive insulin therapy and were followed for 1 year, β-cell function was evaluated with fasting plasma C-peptide and glucagon-stimulated and mixed meal-stimulated C-peptide concentrations. In both groups, insulin doses were comparable, and HbA1c levels were near normal during follow-up. At diagnosis of IDDM, fasting C-peptide was 0.40 ± 0.13 nmol/l in the experimental-therapy group and 0.39 ± 0.23 nmol/1 in the intensive-therapy group. Irrespective of treatment, a slight decline of fasting C-peptide was observed in sequential measurements up to 12 months in both groups (Δ, -0.13 and -0.08 nmol/1, respectively; NS). Glucagon-stimulated C-peptide concentrations decreased from 0.54 ± 0.18 and 0.70 ± 0.39 nmol/l at month 0 to 0.41 ± 0.20 and 0.61 ± 0.52 nmol/1, respectively, at month 12. In the experimental-therapy group, mixed meal-stimulated C-peptide concentrations (area under the curve over 2 h) increased from 82.10 ± 43.72 to 101.20 ± 32.53 nmol/L and in the intensive-therapy group, from 75.05 ± 46.01 to 107.20 ± 102.51 nmol/1. Changes in stimulated C-peptide concentrations between month 0 and 12 were not significant in both groups. During follow-up, fasting and stimulated C-peptide concentrations were not significantly different between the experimental-therapy group and the intensive-therapy group. We conclude that as initial treatments of newly diagnosed IDDM, high-dose intravenous insulin infusion and intensive insulin therapy equally preserve β-cell function during the 1st year of insulin therapy.
Role of Angiotensin II and Bradykinin in Experimental Diabetic Nephropathy: Functional and Structural Studies
Authors: Allen Terri J , Cao Zemin , Youssef Sherif , Lennart Hulthen U , Cooper Mark E
Published: September 2013

We explored the relative roles of the suppression of angiotensin II and the prevention of bradykinin degradation in mediating the renoprotective effects of ACE inhibitors in experimental diabetic nephropathy. Over a 24-week period, we studied male Sprague-Dawley diabetic and control rats and Sprague-Dawley diabetic rats treated with the ACE inhibitor ramipril, the angiotensin II-AT1 receptor antagonist valsartan, the bradykinin-B2 receptor antagonist HOE 140 (icatibant), and a combination of ramipril and icatibant. Serial measurements of urinary albumin excretion, blood pressure, and glycated hemoglobin were performed monthly. After 6 months, the animals were killed for the measurement of kidney weight and the assessment of glomerular ultrastructure. Over 24 weeks, urinary albumin excretion showed a continuous rise in the untreated diabetic rats. Both ramipril and valsartan, which were equihypotensive, prevented the increase in urinary albumin excretion over the whole study period. Icatibant therapy did not attenuate the antialbuminuric effect of the ACE inhibitor, nor did it have any effect as the sole therapy. Diabetes was associated with increased glomerular basement membrane thickness, glomerular volume, and total mesangial volume. Both ACE inhibition and angiotensin II receptor antagonism attenuated the glomerular ultrastructural changes to a similar degree. Icatibant did not attenuate the effects of ramipril on glomerular morphology. ACE inhibitors and angiotensin II-ATE receptor blockers appear to confer similar benefits in experimental diabetic nephropathy, and bradykinin-B2 receptor blockers do not influence this effect. These findings suggest that the blockade of angiotensin II is the major pathway responsible for renoprotection afforded by ACE inhibition in experimental diabetic nephropathy.
Evidence for Association Between the Class I Subset of the Insulin Gene Minisatellite (IDDM2 Locus) and IDDM in the Japanese Population
Authors: Awata Takuya , Kurihara Susumu , Kikuchi Chitose , Takei Shin-ichiro , Inoue Ikuo , Ishii Chikara , Takahashi Keiichi , Negishi Kiyohiko , Yoshida Yoko , Hagura Ryoko , Kanazawa Yasunori , Katayama Shigehiro
Published: September 2013

Although the shortest (class I) minisatellite (i.e., variable number of tandem repeats [VNTR]) alleles in the 5′ region of the insulin gene are positively associated with IDDM in Caucasians, the majority of Japanese are homozygous for class I alleles. Here, we determined the exact length, in number of repeat units (RUs), of class I alleles in Japanese subjects. The distribution of class I alleles in Japanese was trimodal, with peaks located at 32/33, 41, and 44 RUs. The shortest component (i.e., 1S [25-38 RUs]) alleles were significantly increased in the IDDM group compared with the control group (54 vs. 46%; P = 0.040). The 1S/1S genotype was significantly increased in the IDDM patients (34 vs. 20%; P = 0.005; relative risk 2.1). Furthermore, the transmission disequilibrium test of Japanese families with 1S/1M or 1S/1L heterozygous parents confirmed the association of 1S alleles: 17 alleles of 1S and 6 alleles of 1M (39-41 RUs) or 1L (42-44 RUs) were transmitted to affected offspring (P = 0.022). In addition, we found tight linkage of 1S with allele 9 of the tyrosine hydroxylase gene microsatellite and allele (-) of the IGF-II gene Apa I polymorphism, but neither 9 nor (-) alleles were significantly associated with IDDM. The present study suggests that a class I subset may have a role in IDDM susceptibility in Japan. It was revealed that the difference between 1S alleles and 1M or 1L alleles is almost consistently characterized by a sequence variation generated by deletion of two copies of an ACAGGGGTCC CGGGG repeat element, implying that sequence variation of class I alleles may influence disease susceptibility.
Identification of Mutations in the Hepatocyte Nuclear Factor (HNF)-1α Gene in Japanese Subjects With IDDM
Authors: Yamada Shirou , Nishigori Hidekazu , Onda Hideaki , Utsugi Toshihiro , Yanagawa Tatsuo , Maruyama Taro , Onigata Kazumichi , Nagashima Kanji , Nagai Ryozo , Morikawa Akihiro , Takeuchi Toshiyuki , Takeda Jun
Published: September 2013

One form of maturity-onset diabetes of the young, MODY3, is characterized by a severe insulin secretory defect, compared with MODY2, a glucokinase-deflcient diabetes. It has recently been shown that mutations of the gene encoding the transcription factor hepatocyte nuclear factor (HNF)-1α cause MODY3. Because of the rapid progress to overt diabetes and the high prevalence of required insulin treatment in patients with MODY3, we screened the HNF-1α gene for mutations in Japanese subjects with IDDM. Ten exons and flanking introns of the HNF-1α gene in these subjects were amplified by polymerase chain reaction and direct sequencing of the products. Mutations were identified in three (5.5%) of the 55 unrelated subjects with IDDM. A missense mutation of R272H (replacement of Arg by His in codon 272) in the DNA binding domain of HNF-1α was found in a subject who developed IDDM 1 year after diagnosis of NIDDM at 8 years of age. A frameshift mutation of P291fsinsC (insertion of a C in a polyC tract around codon 291 for Pro), which would generate a mutant truncated protein of 340 amino acids, was found in a subject who started insulin treatment when hyperglycemia and ketonuria were noticed at 13 years of age. A missense mutation of R583G (replacement of Arg by Gly in codon 583) in the transactivation domain of HNF-1α was found in a subject with sudden-onset IDDM at 20 years of age. None of these mutations were present in 100 nondiabetic subjects (200 normal chromosomes). These results indicate that the HNF-1α gene defects could lead to the development of not only early-onset NIDDM but also IDDM, implicating the importance of subclassification of HNF-1α-deficient IDDM from a classical type of autoimmune-based IDDM in Japanese.
An Economic Comparison of Pesticide Applications for Processing and Table Tomatoes: A Case Study for Turkey
Authors: Engindeniz Sait , Cosar Gorkem Ozturk
Published: September 2013

In many circumstances, pesticides are the only effective means of controlling disease organisms, weeds, or insect pests. Yet, pesticides are toxic and potentially hazardous to humans, other animals and organisms, and the environment. Therefore, people who use pesticides or regularly come in contact with them must understand the relative toxicity, potential health effects, and preventative measures to reduce the exposure to the products they use. Today, farm-level costs include the costs of the pesticides, and their application. This study was conducted to analyse the farm-level economics of pesticide use on the processing and table tomato growing in selected regions of Turkey. Data was collected from 59 processing tomato farmers and 30 table tomato farmers. These farmers were willing to have their data recorded. According to the results of the study, the average usage concerning the active ingredient of pesticides for the processing and table tomatoes were 4,825.02 and 5,273.86 g/ha. Average pesticide and pesticide application costs of the processing and table tomatoes were determined to be $445/ha and $502/ha, respectively. The breakeven yields for the processing and table tomatoes were calculated to be 3,708 and 3,138 kg/ha, repectively.
Effect of Winter Cover Crop Biomass on Summer Weed Emergence and Biomass Production
Authors: Hertwig Bittencourt Henrique von , Lovato Paulo Emílio , Comin Jucinei José , Lana Marcos Alberto , Altieri Miguel Angel , Costa Murilo Dalla , Gomes José Carlos
Published: September 2013

A greenhouse assay was carried out to evaluate the effect of winter cover crop residues on spontaneous plants that commonly occur on summer annual fields in Southern Brazil. Dry shoot residues of rye (Secale cereale), vetch (Vicia villosa), fodder radish (Raphanus sativus), and a mix of the three species, were applied over pots that had been seeded with alexandergrass (Brachiaria plantaginea), hairy beggarticks (Bidens pilosa), wild poinsettia (Euphorbia heterophylla), and morning glory (Ipomoea grandifolia) at four different depths (0, 1, 2, or 4 cm). Plant emergence and biomass production were measured. Residues of rye reduced the emergence of B. plantaginea, while vetch diminished I. grandifolia and B. plantaginea emergence. Fodder radish reduced emergence of I. grandifolia. The mix of cover crops reduced emergence of I. grandifolia, B. plantaginea, and B. pilosa. None of the cover crops differed from the control on E. heterophylla emergence. The lowest yields in spontaneous plant shoot biomass were obtained from the cover with rye + vetch + fodder radish. The lowest values of root biomass occurred under cover with rye, fodder radish or the mix. Use of vetch residues decreased emergence of B. plantaginea and I. grandifolia, but enhanced biomass accumulation by the latter
Sublethal Effects of Spinosad (Tracer®) on the Cotton Leafworm (Lepidoptera: Noctuidae)
Authors: Abouelghar Gamal Elsayed , Sakr Hanem , Ammar Hager Ali , Yousef Adel , Nassar Moustafa
Published: September 2013

The effects of sublethal concentrations of spinosad (Tracer®) on development, fecundity, and food utilization, in the cotton leafworm, Spodoptera littoralis (Boisd.) were investigated. The fourth-instar larvae were fed on castor bean leaves treated with LC25 (13.9 ppm) or LC50 (57.8 ppm) of spinosad. Pupation and pupal weight were significantly reduced in both LC25 and LC50 treatments, compared with those of the controls. The fecundity rates of females in either LC25 or LC50 treatment were also reduced, compared with the controls. The residual activity of spinosad, applied on cotton at labeled field- and subfield-rates (200 and 70 g active substance (a.s.)/ 200 l water, respectively), was examined against the fifth-instar larvae of S. littoralis. Feeding deterrent effects were significantly demonstrated in larvae that fed on leaves collected from field plots with residual deposits of spinosad at 3 and 7 days old after application (DAA). The residual activity of spinosad on feeding and other metabolic parameters was decreased after 21 DAA indicating that the chemical started to degrade under field conditions. A histological study on midgut from larvae that previously fed on leaves treated with a concentration corresponding to the labeled-field rate of spinosad showed some alterations occurred after 48 and 96 h of treatment, compared to the normal midgut from the controls. The histological alterations included degeneration in the epithelial lining of the midgut and in the peritrophic matrix. Such histopathological effects are presumed to be responsible for the reduction in growth and food utilization caused by spinosad. It is, therefore, concluded that spinosad has sublethal effects on S. littoralis that may affect population dynamics in the field via reductions in survival and reproduction
Multiplex RT-PCR Reaction for Simultaneous Detection of Tomato Torrado Virus and Pepino Mosaic Virus Co-Infecting Solanum Lycopersicum
Authors: Wieczorek Przemysław , Obrępalska-Stęplowska Aleksandra
Published: September 2013

The tomato (Solanum lycopersicum L.) is cultivated all over the world and is a vegetable of significant economic importance. However, an increased production of the vegetable is directly connected with an elevated occurrence of pathogens limiting the production efficiency of the vegetable. Both, Tomato torrado virus and Pepino mosaic virus have been found to be serious disease factors. When not controlled, these viruses can significantly decrease tomato cultivation. In this article, we report a multiplex reverse transcription-polymerase chain reaction (RT-PCR) protocol for simultaneous detection of both, Tomato torrado virus (ToTV) and Pepino mosaic virus (PepMV) in virus infected plants. The assay was designed to specifically amplify the conserved regions of genomic ribonucleic acid (RNA) of both viruses. Moreover, the glycerandehyde 3-phosphate dehydrogenase (GAPDH) was used as an internal control of amplification to exclude false-negative assay results. High-resolution melt analysis of generated RT-PCR products was additionally performed to increase sensitivity and double-check the specificity of the reaction without the need of subsequent complementary deoxyribonucleic acid (cDNA) sequencing