Ahmad Kantar

Diabetes mellitus induces red blood cell plasma membrane alterations possibly affecting the aging process

Various alterations of red blood cell (RBC) plasma membrane appear both in diabetes mellitus and during the physiological aging process. Diabetes mellitus decreases RBC life-span; therefore, it may change the plasma membrane by acting through its effect on the aging process. In order to clarify the issue, RBCs from normal subjects and insulin-dependent diabetic patients were fractionated in five subpopulations of different mean age (fraction 1: early young RBC, fraction 5: mature RBC). Thereafter, plasma membranes were prepared and enzymatic activities, membrane fluidity and lipid peroxidation were evaluated. NA+, K(+)-ATPase activity decreased during aging and it was higher in all RBC subpopulations from normal subjects in comparison to diabetic patients. Next, lipid peroxidation and fluidity increased during aging in both the study groups; in this case, however, in all subpopulations, except for that from fraction 1, RBCs from diabetic patients showed higher membrane fluidity and lipid peroxidation in comparison to normal subjects. Data herein reported suggest that diabetes mellitus affects the plasma membrane independently of (lipid peroxidation and fluidity) or dependently on (Na+, K(+)-ATPase) its effect on aging. In the case of lipid peroxidation and fluidity diabetes mellitus seems to affect the membrane by decreasing RBC life span, whereas in the case of Na+K(+)-ATPase it seems to alter this enzymatic activity which in turn might affect RBC aging. Acetylcholinesterase activity decreased during aging in RBCs from normal subjects, but it increased in RBCs from diabetic patients; RBC subpopulation from fraction 1, on the other hand, showed similar values in normal subjects and diabetic patients. In this case the effect of diabetes mellitus appears only during aging.

Changes of fluorescence anisotropy in plasma membrane of human polymorphonuclear leukocytes during the respiratory burst phenomenon

Steady state fluorescence anisotropy (r s) of TMA‐DPH was measured to study the effect of respiratory burst activation with PMA, FMLP, and PAF on the physico‐chemical structure of PMNs plasma membrane. Our results show a significant increase in r s during the respiratory burst activation. In the presence of NADPH‐oxidase inhibitor DPI, only PAF induces changes in r s values. This suggests a non‐specific effect of PAF on plasma membrane. Azide, which induces a supranormal release of H2O2, fails to increase the basal r s value after activation. Moreover, the catalase does not abolish the increase in rr s induced upon activation. This rules out the possibility that changes of r s during the respiratory burst activation are attributed mainly to H2O2 release. We conclude that multiple processes accompanying the respiratory burst activation are responsible for the changes in the physico‐chemical properties of PMNs plasma membrane.

Alterations in membrane fluidity of diabetic polymorphonuclear leukocytes

Plasma membrane fluidity of polymorphonuclear leukocytes was investigated in 28 patients with insulin dependent diabetes mellitus and 30 healthy controls. Membrane fluidity was measured by steady-state fluorescence anisotropy of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated into the plasma membrane. The fluorescence anisotropy values in resting (unstimulated) polymorphonuclear leukocytes from diabetic subjects were significantly higher than those of controls (0.318 +/- 0.003 vs 0.287 +/- 0.003, P less than 0.001). The addition of the respiratory burst stimulus phorbol myristate acetate induced a stable increase in fluorescence anisotropy values in both groups. Fluorescence anisotropy values of stimulated polymorphonuclear leukocytes from the diabetic and control groups were not significantly different (P greater than 0.05). These data demonstrate a decrease in plasma membrane fluidity of resting polymorphonuclear leukocytes obtained from diabetic subjects. This finding could be in part explained by an increase in their basal respiratory burst activity.

Minor cerebral alterations observed by magnetic resonance imaging in syndromic children with mental retardation

OBJECTIVE To evaluate the anomalies of the central nervous system (CNS) by magnetic resonance imaging (MRI) in normal subjects and in syndromic patients. METHODS AND MATERIAL Seventy-three normal subjects and 50 different syndromic patients with mental retardation (from 3 months to 16 years) were studied utilizing several morphometric parameters (degree of myelination of the white matter, evaluation of liquoral spaces, septo-caudate distance, Evans index, Aboulezz method, and length, width and angles of corpus callosum). RESULTS A high frequency of anomalies of the corpus callosum, the Chiari anomaly and alterations either of the white matter or of the ventricular and periencephalic system have been observed. CONCLUSION The authors point out the importance of cerebral MRI in the study of CNS in patients with malformation syndromes. The present research, carried out on a large number of both normal subjects and patients with malformation syndromes, represents one of the first systematic studies in this field.

A randomized, double-blind, placebo-controlled, crossover trial of systemic flunisolide in the treatment of children with severe atopic dermatitis

Abstract A multicenter, randomized, double-blind, placebo-controlled, cross-over clinical study was performed to determine the effects of systemic flunisolide on the symptoms of 20 children with chronic severe atopic dermatitis. The study lasted 5 weeks. Ten of the 20 patients received flunisolide for 2 weeks followed by placebo for 2 weeks; the other 10 patients received placebo for 2 weeks and then flunisolide for 2 weeks. A 1-week washout period separated the administration of each treatment. Clinical symptoms were assessed at baseline (week 0) and weeks 2, 3, and 5. Total clinical severity scores indicated a significant improvement of symptoms in patients after 2 weeks of flunisolide treatment, compared with the placebo group. After treatment with flunisolide, no worsening of symptoms or relapse occurred. In the placebo group, no significant reduction in clinical scores was observed and, moreover, three patients demonstrated worsening of symptoms during the washout period that followed the placebo treatment. However, this group had a prompt reduction in clinical scores after administration of flunisolide. No side effects were observed during the study. The data suggest that, in children with severe atopic dermatitis, short courses of flunisolide can provide relief while awaiting response to other agents or during severe exacerbations of symptoms. Thus flunisolide is an alternative to traditional oral steroids and has no noticeable side effects.

A study of the Interaction Between Cetirizine and Plasma Membrane of Eosinophils, Neutrophils, Platelets and Lymphocytes using A fluorescence Technique.

The effect of cetirizine on plasma membrane fluidity and heterogeneity of human eosinophils, neutrophils, platelets and lymphocytes was investigated using a fluorescence technique. Membrane fluidity and heterogeneity were studied by measuring the steady-state fluorescence anisotropy and fluorescence decay of 1-(4- trimethylammonium-phenyl)-6-phenyl-1, 3, 5-hexatriene (TMA-DPH) incorporated in the membrane. The results demonstrate that cetirizine (1 μg/ml) induced a significant increase in the Hpid order in the exterior part of the membrane and a decrease in membrane heterogeneity in eosinophils, neutrophils and platelets. Moreover, cetirizine blocked the PAF induced changes in membrane fluidity in these cells. Cetirizine did not influence significantly the plasma membrane of lymphocytes. These data may partially explain the effect ofcetirizine on inflammatory cell activities.

Alterations in erythrocyte membrane fluidity in children with trisomy 21: a fluorescence study

Membrane fluidity of erythrocytes obtained from 15 children with trisomy 21 and 20 healthy controls were studied by measuring steady‐state fluorescence anisotropy and fluorescence lifetime of 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) and 1‐(4‐trimethylammoniumphenyl)‐6‐phenyl‐1,3,5‐hexatriene (TMA‐DPH) incorporated in hemoglobin‐free erythrocyte membranes. Our results demonstrate a significant decrease in DPH fluorescence anisotropy and a significant increase in TMA‐DPH fluorescence anistropy in erythrocytes from subjects with trisomy 21. No significant differences between the two groups were observed in the fluorescence lifetime of DPH and TMA‐DPH. These data suggest an increase in membrane fluidity in the interior part of the membrane and a decrease in fluidity at the lipid‐water interface region. This could be in part attributed to an increased oxidative damage in trisomy 21.

Effect of imidazole salicylate on the respiratory burst of polymorphonuclear leukocytes

Abstract The effect of imidazole salicylate (IS), an organic salt of imidazole and salicylic acid, on the respiratory burst of polymorphonuclear leukocytes (PMNs) was investigated using a chemiluminescence (CL) assay. Luminol- and lucigenin-amplified CL of PMNs stimulated with N-formyl-methionyl-leucyl-phenylalanine (FMLP) or phorbol myristate acetate (PMA) were evaluated in the absence or presence of 1 to 4 μg/ml of IS. Luminol-amplified CL of PMNs activated with FMLP was significantly reduced in the presence of IS, whereas no significant effect was observed on PMA-stimulated PMNs. Lucigenin-amplified CL of PMA-stimulated PMNs was significantly inhibited by IS. CL of the xanthine/xanthine oxidase system was abolished in the presence of IS. These results suggest that IS is a scavenger of the superoxide anion and that it can influence the respiratory burst of PMNs, probably by interacting with the plasma membrane.

Interaction of trout hemoglobin with H2O2: a chemiluminescence study

Erythrocytes from trout Salmo irideus are characterized by four different hemoglobin components (HbI, HbII, HbIII and HbIV), HbI and HbIV being predominant. In this study we describe the interaction between trout hemoglobin (HbI and HbIV) and H2O2 using a chemiluminescence assay. Our data show that the reaction of hemoglobins with H2O2 produces a time-limited and significant increase of chemiluminescence signal. The half-life of the decay of this chemiluminescence signal was characteristic for each type of hemoglobin used. These results indicate the formation of excited molecules related to the interaction between trout hemoglobin and H2O2.

Interaction between PAF and human platelet membranes' a fluorescence study

The interaction between PAF and human platelet membranes was investigated by measuring the steadystate fluorescence anisotropy and fluorescence decay of 1 (4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated in platelet plasma membranes. PAF induced a time-limited and significant increase of the lipid order in the exterior part of the membrane and a decrease in membrane heterogeneity. These changes were blocked in the presence of the PAF antagonists, L-659,989 and 1-O-hexadecyl-2-acetyl-sn-glycero-3-phospho(N,N,N-trimethyl)hexanolamine.H2O. These results indicate that the observed changes in the physico-chemical properties of the membrane are attributed to the PAF–receptor interaction and signal transduction.