Inhaled salbutamol decreases blood ammonia levels during exercise in normal subjects

The present study examines the effect of salbutamol, a beta2-adrenoreceptor agonist, on blood ammonia levels during an incremental cycle exercise test in healthy non-asthmatic subjects. Blood ammonia levels were lower after inhalation of 400 mcg of salbutamol than after placebo during submaximal exercise: 33+/-2 micromol x l(-1) v.s. 48+/-9 micromol x l(-1) at 220 W and 39+/-2 micromol x l(-1) v.s. 50+/-4 micromol x l(-1) at 260 W. At peak exercise there were no significant differences. The results suggest that beta2-adrenoreceptors are involved in the regulation of blood ammonia during exercise.     

Comparative RFLP mapping of the chlorotoluron resistance gene (Su1) in cultivated wheat (Triticum aestivum) and wild wheat (Triticum dicoccoides)

Chlorotoluron is a selective phenylurea herbicide widely used for broad-leaved and annual grass weed control in cereals. Variation in the response to chlorotoluron (CT) was found in both hexaploid bread wheat (Triticum aestivum L.) and wild tetraploid wheat (Triticum dicoccoides KöRN.). Here, we describe the comparative mapping of the CT resistance gene (Su1) on chromosome 6B in bread and wild wheat using RFLP markers. In bread wheat, mapping was based on 58 F₄ single-seed descent (SSD) plants of the cross between a genotype sensitive to chlorotoluron, ‘Chinese Spring’ (CS), and a resistant derivative, the single chromosome substitution line, CS (‘Cappele-Desprez’ 6B) [CS (CAP6B). In T dicoccoides, mapping was based on 37 F₂ plants obtained from the cross between the CT-susceptible accession B-7 and the resistant accession B-35. Nine RFLP probes spanning the centromere were chosen for mapping. In bread wheat Su1 was found to be linked to α-Amy-1 (9.84 cM) and Xpsr371 (5.2 cM), both on the long arm of 6B, and Nor2 (2.74 cM) on the short arm. In wild wheat the most probable linkage map was Nor2-Xpsr312-Su1-Pgk2, and the genetic distances between the genes were 24.8cM, 5.3cM, and 6.8cM, respectively. These results along with other published map data indicate that the linear order of the genes is similar to that found in T. aestivum. The results of this study also show that the Su1 gene for differential response to chlorotoluron has evolved prior to the domestication of cultivated wheat and not in response to the development and use of chemicals.     

Influence of alloxan-induced diabetes and selenite treatment on blood glucose and glutathione levels in mice

Many clinical studies reported that diabetic patients had lower glutathione contents in erythrocytes or plasma. Recently, selenium, an essential trace element with well-known antioxidant characteristics, has been found to have insulin-mimetic properties. But seldom information is available about the influence of selenium on glutathione changes induced by diabetes mellitus in animals. Therefore, this study was designed to compare the impacts of selenite treatment on glutathione (GSH) levels of blood and tissues such as brain, kidney, liver, spleen and testis in mice. Four groups were used in this study: a control group, a diabetic group, a selenite-treated normal group and a selenite-treated diabetic group. Selenite was administered to the mice for 4 weeks with an oral dose of 2 mg kg(-1) day(-1) by gavage. The blood glucose level, and GSH level in blood and tissues were determined. The results show that the selenite-treated diabetic group had significantly lower blood glucose levels than the diabetic group. Moreover, alloxan-induced diabetes significantly decreased GSH levels in blood, kidney, liver and testis compared to the controls. Selenite treatment of the diabetic mice only improved the GSH levels in liver and brain. On the other hand, selenite administered to the normal mice reduced GSH levels in the liver compared to the controls. In conclusion, this study suggests that selenite treatment of diabetic mice with an effective dose would be beneficial for the antioxidant system of liver and brain although it exerts a toxic effect on the liver of normal mice.     

Identification and mapping of random amplified polymorphic DNA (RAPD) markers linked to resistance against beet necrotic yellow vein virus (BNYVV) in Beta accessions

Molecular markers linked to resistance genes are useful to facilitate the introgression of one or more of these genes in breeding materials. Following the approach of bulked segregant analysis, RAPD markers linked to resistance genes against beet necrotic yellow vein virus were identified in the four Beta accessions Holly-1-4, R104, R128 and WB42. Two primers were found which generate RAPD markers tightly linked to resistance in segregating families of Holly-1-4, R104 and R128, indicating that the resistance genes in these accessions might be situated at the same locus. Other, specific, primers were identified which generate RAPD markers linked to resistance in each of these accessions. Short-range maps were established around the resistance locus in these accessions. For WB42, RAPD markers were only identified at a relatively large distance from the resistance gene. Conversion of three RAPD primers of Holly-1-4, R104 and R128 into STS primers resulted in STS markers which can be readily used for marker-assisted selection in breeding programmes. Received: 8 January 1996 / Accepted: 14 June 1996     

Combined effect of ACE inhibitor and exercise training on insulin resistance in type 2 diabetic rats

The aim of this study was to investigate whether a combined treatment of ACE inhibitor and exercise training is more effective than either treatment alone in alleviating the insulin resistant states in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of type 2 diabetes. OLETF rats (25 weeks old) were randomly divided into 5 groups; sedentary control, exercise-trained, temocapril (ACE inhibitor; 2 mg/kg/day)-treated, with and without exercise, and losartan (AT1 receptor antagonist; 1 mg/kg/day)-treated. Long-Evans Tokushima Otsuka rats were used as a non-diabetic control. Body weight, the amount of abdominal fat and blood pressure were higher for OLETF rats than for control rats. However, glucose infusion rate (GIR), an index of insulin resistance, was decreased greatly in OLETF rats. The fasting levels of blood glucose, insulin and lipids were also increased in the diabetic strain. In OLETF rats, both temocapril and losartan reversed hypertensive states significantly, whereas GIR and hyperlipidemia were improved when rats were treated with ACE inhibitors, but not with the AT1 receptor antagonist. Exercise training decreased body weight and the amount of abdominal fat, and also increased GIR in parallel with improved dislipidemia. The combination of the ACE inhibitor with exercise training also improved obesity, hyperinsulinemia, dislipidemia and fasting level of blood glucose, and this combination resulted in the greatest improvement of insulin resistance. These results suggest that the combination of ACE inhibitor and exercise training may be a beneficial treatment for mixed diabetic and hypertensive conditions.     

Angptl4 deficiency decreases serum triglyceride levels in low-density lipoprotein receptor knockout mice and streptozotocin-induced diabetic mice

Angiopoietin-like protein family 4 (Angptl4) has been shown to regulate lipoprotein metabolism through the inhibition of lipoprotein lipase (LPL). In familial hypercholesterolemia (FH), individuals lacking low-density lipoprotein receptor (LDLR) present not only hypercholesterolemia, but also increased plasma triglyceride (TG)-rich lipoprotein remnants, and develop atherosclerosis. In addition, the most common type of dyslipidemia in individuals with diabetes is increased TG levels.We first generated LDLR^−/−Angptl4^−/− mice to study the effect of Angptl4 deficiency on the lipid metabolism. Fasting total cholesterol, VLDL-C, LDL-C, HDL-C and TG levels were decreased in LDLR^−/−Angptl4^−/− mice compared with LDLR^−/−Angptl4^+/+ mice. In particular, post olive oil-loaded TG excursion were largely attenuated in LDLR^−/−Angptl4^−/− mice compared with LDLR^−/−Angptl4^+/+ mice. We next introduced diabetes by streptozotocin (STZ) treatment in Angptl4^−/− mice and examined the impacts of Angptl4 deficiency. Compared with diabetic Angptl4^+/+ mice, diabetic Angptl4^−/− mice showed the improvement of fasting and postprandial hypertriglyceridemia as well. Thus, targeted silencing of Angptl4 offers a potential therapeutic strategy for the treatment of dyslipidemia in individuals with FH and insulin deficient diabetes.     

Chronic taurine supplementation ameliorates oxidative stress and Na+ K+ ATPase impairment in the retina of diabetic rats

Summary.  This study evaluates the effect of 4 months supplementation with 2% and 5% taurine (w/w) on the retina of diabetic rats. In non-diabetic rats, taurine does not modify glycemia, body weight, retinal conjugated dienes (CD), lipid hydroperoxide (LP), and Na⁺K⁺ATPase activity. In diabetic rat, at 2, 4, 8, 16 weeks following the onset of diabetes, retinal CD and LP are significantly and progressively increased, while pump activity is gradually and significantly reduced. In taurine supplemented diabetic rats, glycemia is not affected but lipid peroxidation is significantly decreased. Finally, taurine preserves ATPase activity being 5% more effective than 2% taurine. We conclude that taurine supplementation ameliorates biochemical retinal abnormalities caused by diabetes, thereby suggesting that taurine may have a role in the prevention of retinal changes in diabetes. Received November 26, 2001 Accepted January 10, 2002 Published online October 3, 2002 Authors' address: Prof. Flavia Franconi, Department of Pharmacology, University of Sassari, Via Muroni 23a, I-07100 Sassari, Italy, Fax: 39-79228715, E-mail: franconi@ssmain.uniss.it     

Superactive somatostatin analog decreases plasma glucose and glucagon levels in diabetic rats

The action of the new analog of somatostatin, D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2 (RC-160), on plasma glucagon and glucose levels was evaluated in streptozotocin-diabetic rats. The effect of this analog on the insulin-induced hypoglycemia in diabetic rats was also investigated in order to evaluate the risk of exacerbating hypoglycemia. Administration of analog RC-160, in a dose of 25 micrograms/kg b. wt. SC, inhibited plasma glucagon secretion and decreased plasma glucose levels. This effect also occurred when plasma glucagon and glucose levels were first elevated by arginine infusion, 1000 mg/kg/hr for 30 min. Subcutaneous injection of regular insulin, 15 U/kg b. wt., produced hypoglycemia with a progressive increase in glucagon levels. Analog RC-160 completely suppressed the hypoglycemia-induced glucagon release for up to 150 min after injection of the analog or insulin. A greater decrease in the plasma glucose level was observed in the group treated with insulin and the analog than in the group injected only with insulin. These results indicate that somatostatin analog RC-160 can produce a marked and prolonged inhibition of glucagon release and a decrease in the plasma glucose level in diabetic rats. This analog may be useful as an adjunct to insulin in the treatment of diabetic patients, although caution should be exercised, to prevent hypoglycemia when using somatostatin analogs together with insulin.     

Early molecular events in the development of the diabetic cardiomyopathy

Summary.  Oxidative damage to DNA has been well documented in cardiac cells isolated from diabetic patients and rats with streptozotocin-induced diabetes mellitus (DM). This study evaluates possible molecular mechanisms for early events in the development of DM-induced cardiomyopathy. Methods: To analyze the mechanism of overexpression of p21^WAF1/CIP1 and inhibition of cyclin D₁ expression in cardiomyocytes of diabetic rats we examined the methylation status of these genes by MS-PCR and assessed the possibility of epigenetic control of their expression. Results: We found that the steady-state expression of both genes is influenced by their methylation status, as an epigenetic event, of their 5′-flanking regions upon development of diabetes. Conclusions: Oxidative damage contributes to the development of cardiomyopathy via p53-dependent activation of cardiac cell death. This pathway includes de novo methylation of the P53-inducible p21^WAF1/CIP1-gene encoding a protein which binds to and inhibits a broad range of cyclin-cyclin-dependent kinase complexes. Received June 29, 2001 Accepted August 6, 2001 Published online August 9, 2002     

Zinc and copper in the serum of diabetic patients

The Zn/Cu ratio was examined in the serum of three groups of persons: healthy volunteers, diabetic patients on diabetic diet (NIDDM), and diabetic patients on diabetic diet and insulin (IDDM). Zinc, copper, the Zn/Cu serum ratio, and the blood glucose level were determined during fasting and 2 h after breakfast. Zn and Cu serum levels in NIDDM and IDDM patients were decreased. The Zn/Cu ratio was higher in both groups of diabetic patients. These changes in the Zn and Cu levels as well as in the Zn/Cu ratio were not related to chronic diabetic complications.     

Selenium and glycogen levels in diabetic patients

Selenium in serum and selenium and glycogen in erythrocytes were determined in diabetic patients divided into noninsulin-dependent (n=50) and insulin-dependent (n=31) groups according to the etiopathogenesis of their diabetes. Selenium was determined by the method of atomic absorption spectrometry. Serum level of selenium was statistically significantly different in patients with either noninsulin-dependent (59.23±12.2 μg/L) or insulin-dependent (58.23±16.7 μg/L) diabetes mellitus as compared with the control group of 62 subjects (64.2±11.5 μg/L; p<0.05). There was no statistically significant difference in the serum levels of selenium between the groups of patients with noninsulin-dependent and insulin-dependent diabetes mellitus. The levels of erythrocyte glycogen were 2.0580±1.326, 2.0380±1.735, and 2.0036±1.3537 μg/g Hb in the control group, noninsulin-dependent group, and insulin-dependent group, respectively, with no statistically significant between-group difference. The decreased levels of selenium in serum and erythrocytes of diabetic patients suggest the possible role of glutathione peroxidase activity.     

Balneotherapy and platelet glutathione metabolism in type II diabetic patients

Effects of balneotherapy on platelet glutathione metabolism were investigated in 12 type II (non-insulin-dependent) diabetic patients. Levels of the reduced form of glutathione (GSH) on admission were well correlated with those of fasting plasma glucose (FPG;r=0.692,P<0.02). After 4 weeks of balneotherapy, the mean level of GSH showed no changes; however, in well-controlled patients (FPG <150 mg/dl), the level increased (P<0.01) and in poorly controlled patients (FPG >150 mg/dl), the value decreased (P<0.05). There was a negative correlation between glutathione peroxidase (GPX) activities and the levels of FPG (r=–0.430,P<0.05). After balneotherapy, the activity increased in 5 patients, decreased in 3 patients and showed no changes (alteration within ±3%) in all the other patients. From these findings in diabetic patients we concluded: (1) platelet GSH synthesis appeared to be induced in response to oxidative stress; (2) lowered GPX activities indicated that the antioxidative defense system was impaired; and (3) platelet glutathione metabolism was partially improved by 4 weeks balneotherapy, an effect thought to be dependent on the control status of plasma glucose levels. It is suggested that balneotherapy is beneficial for patients whose platelet antioxidative defense system is damaged, such as those with diabetes mellitus and coronary heart disease.     

Mapping of two genes for resistance to clubroot (Plasmodiophora brassicae) in a population of doubled haploid lines of Brassica oleracea by means of RFLP and AFLP markers

A genetic map covering 615 cM in 12 linkage groups was assembled based on 92 RFLP and AFLP markers segregating in a population of 107 doubled haploid lines (DH lines) of Brassica oleracea. The DH-line population was obtained through microspore culture from the of two homozygous parents: DH-line Bi derived from the cabbage landrace Bindsachsener, and DH-line Gr from broccoli cv ‘Greenia’. Sixty-five percent of the loci, and in some cases complete linkage groups, displayed distorted segregation ratios, a frequency much higher than that observed in populations of the same species. DH-line Bi was resistant to clubroot, which is caused by a Dutch field isolate of Plasmodiophora brassicae. Resistance in the DH-line population was determined in two ways: by assigning symptom grades to each plant, and by measuring the fresh weights of the healthy and affected parts of the root system of each plant. Using a multiple QTL mapping approach to analyze the fresh weight data, we found two loci for clubroot resistance; these were designated pb-3 and pb-4. The additive effects of these loci were responsible for 68% of the difference between the parents and for 60% of the genetic variance among DH-line means. Also, indications for the presence of two additional, minor QTLs were found. Analysis of symptom grades revealed the two QTLs pb-3 and pb-4, as well as one of the two minor QTLs indicated by analysis of the fresh weight data. Received: 29 April 1996 / Accepted: 10 May 1996     

Effect of acetazolamide on cerebral blood flow and tympanic temperature in healthy subjects and patients with subacute subarachnoid haemorrhage

The influence of the increased cerebral blood flow (CBF) induced by acetazolamide on tympanic temperature (T _ty) was examined in three healthy male volunteers and in five patients with subacute subarachnoid haemorrhage (SAH). The CBF was estimated by means of stable xenon-enhanced computed tomography before and after the administration of acetazolamide. The T _ty was recorded continuously in both ears using thermistor thermometers. In all subjects, CBF increased ranging from 11% to 108% after acetazolamide administration. In all the healthy subjects and in two patients with mild SAH, T _ty was higher than the oesophageal temperature (T _oes) and T _ty decreased bilaterally, ranging from 0.07 to 0.35°C as CBF increased. Three patients with severe SAH were febrile, their T _oes exceeding T _ty, and their T _ty rose by 0.30 to 0.53°C with increased CBF. These observations suggest that T _ty follows brain temperature which changes with an increase in CBF in euthermic subjects as well as in febrile subjects. Accepted: 3 September 1996     

Metformin restores the correlation between serum-oxidized LDL and leptin levels in type 2 diabetic patients

Abstract

Introduction

Leptin has lipid peroxidation properties in healthy individuals. Here we aimed to study the correlation between serum-oxidized low-density lipoprotein (ox-LDL) and leptin levels in patients with type 2 diabetes. We also studied the effect of metformin therapy on the correlation between serum ox-LDL and leptin levels in patients with newly diagnosed diabetes.

Methods

We performed a cross-sectional study on two groups of patients with type 2 diabetes stratified according to (1) patients with newly diagnosed diabetes and (2) patients with long-standing diabetes plus healthy controls. Patients with newly diagnosed diabetes were followed for 3 months after the initiation of metformin therapy.

Results

Patients with type 2 diabetes had a higher serum ox-LDL, ox-LDL/LDL ratio, waist circumference, fasting blood sugars (FBSs), hemoglobin A1C (HbA1C), triglyceride, homeostatic model assessment of insulin resistance (HOMA-IR) and a lower serum leptin levels than controls. Serum ox-LDL, ox-LDL/LDL ratio (0.08 (0.08–0.12) vs. 0.06 (0.05–0.08), P < 0.001) and HOMA-IR (3.26 ± 0.23 vs. 2.93 ± 0.32; P < 0.01) were decreased when serum leptin levels (15.9 ± 1.6 vs. 21.4 ± 2.5, P < 0.01) were increased after 3 months of metformin therapy. This remained significant after multiple adjustments for age, body mass index, FBS, HbA1c, and HOMA-IR. Leptin was significantly correlated with ox-LDL/LDL ratio in controls (r = 0.78, P < 0.01), and in patients with newly diagnosed diabetes (r = 0.4, P < 0.05), after metformin therapy. There were not any correlation between leptin and ox-LDL/LDL ratio in patients with long-standing diabetes and patients with newly diagnosed diabetes before treatment.

Discussion

Metformin restores the positive correlation between serum ox-LDL and leptin levels in patients with type 2 diabetes.     

Immune dysfunction in patients with diabetes mellitus (DM)

Patients with diabetes mellitus (DM) have infections more often than those without DM. The course of the infections is also more complicated in this patient group. One of the possible causes of this increased prevalence of infections is defects in immunity. Besides some decreased cellular responses in vitro, no disturbances in adaptive immunity in diabetic patients have been described. Different disturbances (low complement factor 4, decreased cytokine response after stimulation) in humoral innate immunity have been described in diabetic patients. However, the clinical relevance of these findings is not clear. Concerning cellular innate immunity most studies show decreased functions (chemotaxis, phagocytosis, killing) of diabetic polymorphonuclear cells and diabetic monocytes/macrophages compared to cells of controls. In general, a better regulation of the DM leads to an improvement of these cellular functions. Furthermore, some microorganisms become more virulent in a high glucose environment. Another mechanism which can lead to the increased prevalence of infections in diabetic patients is an increased adherence of microorganisms to diabetic compared to nondiabetic cells. This has been described for Candida albicans. Possibly the carbohydrate composition of the receptor plays a role in this phenomenon.     

Behaviour of interleukin-2 serum levels in advanced non-small-cell lung cancer patients: relationship with response to therapy and survival

 Interleukin(IL)-2 is a T helper (Th) 1 type cytokine that has been shown to play an important role in antitumour immune responses. In this study, the prognostic significance of serum IL-2 levels was investigated in 60 advanced non-small-cell lung cancer (NSCLC) patients. IL-2 serum levels were determined before chemotherapy, at the end of chemotherapy and during follow-up, using a commercially available enzyme-linked immunoadsorbent assay kit. The results were analysed according to the response to therapy and were used to generate a model predicting overall survival and time to treatment failure. All 60 patients were shown to have higher IL-2 serum levels than controls (P < 0.0001). Stage IV patients had significantly lower IL-2 levels than stage III patients (P < 0.0001), although they were still significantly higher than controls (P < 0.0001). It is interesting that, when patients were divided into responders and non-responders according to the response to therapy, the former were shown to have significantly higher pre-chemotherapy levels than the latter (P < 0.0001). Moreover, a further significant increase in IL-2 serum levels (P=0.004) and a significant decrease (P < 0.0001) were shown in responders and non-responders, respectively at the end of the therapy. Using univariate and multivariate analyses, both overall survival and time to treatment failure were shown to be affected by the mean pathological levels of IL-2. Furthermore, the prognostic significance of the serum level of IL-2 was confirmed by the stepwise regression analysis. In conclusion, determination of pre-treatment IL-2 serum levels was shown to be of independent prognostic utility in patients with advanced NSCLC; therefore, its possible use for prediction of outcome is proposed. Received: 16 March 2000 / Accepted: 27 July 2000     

Effects of active and passive hyperthermia on heat shock protein 70 (HSP70)

Summary. The purpose of this study was to delineate the effects of hyperthermia and physical exercise on the heat shock protein 70 (HSP70) response in circulating peripheral blood mononuclear cells (PBMCs). Six healthy, young (age: 24 ± 3 yrs), moderately trained males (VO_2max: 48.9 ± 2.7 ml · kg · min⁻¹) undertook two experimental trials in a randomised fashion in which the core temperature (T _c) was increased and then maintained at 39 °C during a 90 min bout by either active (AH) or passive (PH) means. AH involved subjects cycling at 90% of their lactate threshold in attire designed to impede heat loss mechanisms. In the PH trial, subjects were immersed up to the neck in a hot bath (40.2 ± 0.4 °C), once the critical T _c was achieved, intermittent cycling and water immersions were prescribed for the AH and PH conditions, respectively, to maintain the T _c at 39 °C. HSP70 was measured intracellularly pre, post and 4 h after trials, from circulating PBMCs using an ELISA technique. T _c reached 39 °C quicker in PH than during AH trials (PH: 21 ± 4 min vs. AH: 39 ± 6 min; P < 0.01), thereafter T _c was maintained around 39 °C (PH: 39.1 ± 0.2 °C; AH: 38.8 ± 0.3 °C; P > 0.05). AH induced a marked leukocytosis in all sub-sets (P < 0.05). PH generated significant monocytosis and granulocytosis (P < 0.05), without changes in lymphocyte counts (P > 0.05). There were no significant increases in intracellular HSP70 at 0 h (AH: Δ − 21.1 ± 44.8; PH: Δ + 12.5 ± 32.4 ng/mg TP/10³/μl PBMCs; P > 0.05) and 4 h (AH: Δ − 30.0 ± 40.1; PH: Δ + 36.3 ± 70.4 ng/mg TP/10³/μl PBMCs; P > 0.05) post active and passive heating. Peak HSP70 expressed as a fold-change from rest was also not increased by AH (1.1 ± 0.9; P > 0.05) or PH (3.2 ± 4.8; P > 0.05). There were no significant differences between the AH and PH trials at any time-point, and the HSP70 response appeared to be individual specific. These results did not allow us to delineate the effects of hyperthermia and other exercise associated stressors on the heat shock response and therefore further work is warranted. Authors’ address: Ric Lovell, Department of Sport, Health and Exercise Science, University of Hull, Hull HU6 7RX, U.K.     

Relation of blood glucose levels to the changes in plasma levels of various hydrolytic enzymes in diabetic patients

Plasma levels of various hydrolytic enzymes in diabetic patients, as diagnosed by their blood glucose levels, were compared with those of control subjects. Most of the levels of the aminopeptidase activities examined were significantly increased, while those of angiotensin-converting enzyme (ACE) and esterase decreased, in diabetic patients. The results of multivariate analysis suggest that the increased aminopeptidase activities are related rather to secondary organ lesions than to the primary pancreatic lesion. It seems that the blood glucose level is not necessarily a good indicator of metabolic abnormalities underlying this pathological condition.