Vezivanje glikozilfosfatidilinozitola(GPI-a) za membranske proteine eritrocita pod dejstvom insulina

In this work GPI binding to membrane proteins from erythrocytes of insulinoma patients for whom prolonged hyperinsulinism and hypoglycemia were characteristic, as well as from normal erythrocytes incubated with supraphysiological concentrations of insulin were analyzed. In the RBCs from insulinoma patients, covalent GPI binding to red cell membrane proteins in the spectrin/ankyrin region, band 4.1 and two proteins of molecular mass of 115 and 110 kD was demonstrated. In erythrocytes incubated with insulin label was associated with band 4.1 and two proteins of molecular mass of 115 and 110 kD. Extraction studies showed that the 100-kD proteins are unrelated to band 3 since they were found in Triton- prepared cytoskeleton. To our knowledge this is the first demonstration of such a modification of red cell skeletal proteins, and the first demonstration of post-translation GPI binding to red cell skeletal proteins in response to insulin. A mechanism proposed for GPI binding to red cell skeletal proteins as well as the relevance of these results for physiological disorders that are characterized by hyperinsulinism are briefly discussed.U ovom radu ispitivano je vezivanje GPI-a za membranske proteine eritrocita pacijenata obolelih od insulinoma, za koje su karakteristični dugotrajni hiperinsulinizam i hipoglikemija, kao i u normalnim eritrocitima inkubiranim sa suprafiziološkim koncentracijama insulina. Nađeno je da u eritrocitima pacijenata dolazi do kovalentnog vezivanja GPI-a za membranske proteine eritrocita i to u oblasti spektrina i ankirina, za traku 4.1. i dva proteina molekulskih masa 115 i 110kD. U eritrocitima inkubiranim sa insulinom GPI se vezuje za traku 4.1. i dva proteina molekulskih masa 115 i 110 kD. Utvrđeno je da proteini mase 100 kD ne potiču od trake 3, jer su detektovani u citoskeletnoj frakciji zaostaloj posle ekstrakcije membranskih proteina rastvorom Triton-a. U ovom radu je prvi puta detektovana modifikacija citoskeletnih proteina eritrocita vezivanjem GPI-a, kao i post-translaciono vezivanje GPI-a za citoskeletne proteine eritrocita pod uticajem insulina. Ukratko je diskutovan mehanizam vezivanja GPI-a za proteine citoskeleta eritrocita, kao i značaj dobijenih rezultata za razumevanje fizioloških poremećaja u hiperinsulinizmu

Activities of antioxidative defence enzymes in the blood of patients with amyotrophic lateral sclerosis - Base for controled trial of antioxidants combination

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Lipid status, anti-oxidant enzyme defence and haemoglobin content in the blood of long-term clozapine-treated schizophrenic patients

Objective: Despite clozapine's unique effectiveness in patients with schizophrenia, a number of adverse effects have been recognised including abnormalities in lipid and glucose metabolisms. A high clozapine level in red blood cells (RBCs) and disturbed anti-oxidant enzyme activities in blood from schizophrenic patients prompted us to investigate lipid status and anti-oxidant enzyme defence in the blood of chronic schizophrenic patients on long-term clozapine therapy. Methods: Plasma lipids, RBC anti-oxidant enzyme activities and haemoglobin (Hb) content were measured using established procedures in a group of eighteen chronically-medicated (average 630 days of therapy) schizophrenic patients receiving clozapine (average dose of 295 mg/day) and data were compared with those from a group of eighteen well-matched normal controls. Results: Significantly higher levels of plasma triglycerides (by 47%, p<0.01) and total cholesterol and phospholipids (by 8% and 11%, respectively p<0.05) in patients were found. CuZn-superoxide dismutase (SOD1) activity was markedly higher (by 35%, p<0.001) while selenium-dependent glutathione peroxidase (GSH-Px1) activity was markedly lower (by 41%, p<0.001) in patients. In addition, metHb and HbA1c levels in patients were significantly higher (by 58% and 25%. respectively p<0.001). SOD1 activity was negatively correlated (p<0.001) to GSH-Px1 activity in patients. Conclusions:The findings support the view that ongoing oxidative stress may be a mechanism by which clozapine induces some adverse effects that increase the risk of diabetes and metabolic syndrome. If valid, this would indicate that in parallel with long-term clozapine treatment, schizophrenic patients could be encouraged to make some lifestyle changes to limit the detrimental effects of the medication. (C) 2009 Elsevier Inc. All rights reserved.Ministry of Science and Technological Development of the Republic of Serbia [142017, 143034

Biotransformation of nitric oxide in the cerebrospinal fluid of amyotrophic lateral sclerosis patients

Recent findings indicate that nitric oxide (NOcenter dot) over-production might be an important factor in the pathogenesis of sporadic amyotrophic lateral sclerosis (SALS). We measured significantly higher concentrations of uric acid and thiol group-containing molecules (R-SH groups) in the cerebrospinal fluid (CSF) from SALS patients compared to controls. The above factors, together with a slightly increased free iron concentration found in the CSF, favour conditions necessary for the formation of the dinitrosyl iron complex, capable of NOcenter dot bio-transformation. Thus, we performed ex vivo saturation of CSF ( from both SALS patients and controls) with NOcenter dot. A decrease in the level of R - SH was found. This was more pronounced in the CSF from SALS patients. In the CSF from SALS patients the production of nitrite and hydroxylamine was greater than that observed in the CSF from controls. Moreover, we also found increased Cu, Zn-SOD activity in the CSF from SALS patients ( when compared to control subjects) but no activity corresponding to Mn-SOD in any CSF samples. As Cu, Zn-SOD can react with nitroxyl forming NOcenter dot, the conditions for a closed, but continuous, loop of NOcenter dot biotransformation are present in the CSF of ALS patients.nul

Biotransformation of nitric oxide in the cerebrospinal fluid of amyotrophic lateral sclerosis patients

Recent findings indicate that nitric oxide (NOcenter dot) over-production might be an important factor in the pathogenesis of sporadic amyotrophic lateral sclerosis (SALS). We measured significantly higher concentrations of uric acid and thiol group-containing molecules (R-SH groups) in the cerebrospinal fluid (CSF) from SALS patients compared to controls. The above factors, together with a slightly increased free iron concentration found in the CSF, favour conditions necessary for the formation of the dinitrosyl iron complex, capable of NOcenter dot bio-transformation. Thus, we performed ex vivo saturation of CSF ( from both SALS patients and controls) with NOcenter dot. A decrease in the level of R - SH was found. This was more pronounced in the CSF from SALS patients. In the CSF from SALS patients the production of nitrite and hydroxylamine was greater than that observed in the CSF from controls. Moreover, we also found increased Cu, Zn-SOD activity in the CSF from SALS patients ( when compared to control subjects) but no activity corresponding to Mn-SOD in any CSF samples. As Cu, Zn-SOD can react with nitroxyl forming NOcenter dot, the conditions for a closed, but continuous, loop of NOcenter dot biotransformation are present in the CSF of ALS patients.nul