Biomedical subjects

A Kantar

Publications and source records attributed to A Kantar.

29 records · Page 2Linked to original sources

PubMed1991

Effect of PAF on erythrocyte membrane heterogeneity: a fluorescence study.

The effect of platelet activating factor, PAF, on the erythrocyte membrane heterogeneity was investigated by measuring the steady-state fluorescence anisotropy and fluorescence decay of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated in hemoglobin-free erythrocyte membranes. PAF induced a significant increase of the lipid order in the exterior part of the membrane and a decrease in membrane heterogeneity. These results indicate that PAF may cause changes in the physico-chemical structure of the erythrocyte membrane.

Diphenylhexatriene↗

PubMed1991

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.

Child↗

PubMed1990

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

Steady state fluorescence anisotropy (rs) 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 rs during the respiratory burst activation. In the presence of NADPH-oxidase inhibitor DPI, only PAF induces changes in rs 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 rs value after activation. Moreover, the catalase does not abolish the increase in rs induced upon activation. This rules out the possibility that changes of rs 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.

Adult↗

PubMed1990

Alterations of the respiratory burst of polymorphonuclear leukocytes from diabetic children. A chemiluminescence study.

The respiratory burst of polymorphonuclear leukocytes was investigated in 24 children with insulin dependent diabetes mellitus and 24 healthy controls. This oxygen dependent, membrane associated process generates a number of toxic oxygen metabolites which are implicated in the pathogenesis of endothelial damage. The activity of polymorphonuclear leukocytes was studied in terms of luminol amplified chemiluminescence. It was found that the resting luminol amplified chemiluminescence activity of isolated polymorphonuclear leukocytes from diabetic children was significantly higher than that of controls (342,000 +/- 174,000 cpm vs. 165,000 +/- 82,000 cpm, p less than 0.01). The addition of respiratory burst inhibitors caused a significant reduction of basal chemiluminescence (greater than 80%). When the ratio of phorbol myristate acetate stimulated activity to basal activity was calculated and used as an activation index, it was found to be significantly reduced in diabetics relative to controls (4.29 +/- 2.46 vs. 8.34 +/- 3.21, p less than 0.01). These observations suggest that increased release of toxic oxygen metabolites from polymorphonuclear leukocytes in diabetic subjects may play a role in the development of diabetic angiopathies.

Adolescent↗

PubMed1990

Steady state fluorescence polarization and Fourier transform infrared spectroscopy studies on membranes of functionally senescent human erythrocytes.

Human erythrocytes were separated using Percoll/Albumin density gradient centrifugation into 5 subpopulations which represent cell subpopulations of different ages. The physico-chemical properties of the membranes and their lipid extracts, prepared from the 5 subpopulations, were studied by 1,6-diphenyl-1,3,5-hexatriene fluorescence polarization and by Fourier Transform Infrared Spectroscopy respectively. The fluorescence polarization data show a decrease of membrane fluidity in the youngest erythrocyte fraction and the infrared spectroscopy reveals a lower degree of unsaturation of the lipids from this fraction. Changes of membrane fluidity among the 5 erythrocyte subpopulations is assigned to the variations of the degree of unsaturations of lipids rather than to variations of cholesterol content.

Adult↗

PubMed1989

Modifications of erythrocyte membrane fluidity of in vivo functionally aged human erythrocytes.

The process of red blood cell senescence in the blood stream results in many changes in their physical and biochemical properties. In this work we have studied the physico-chemical state of erythrocyte membranes prepared from 5 subpopulations of erythrocytes of different age by using the fluorescence technique. Membrane fluidity has been evaluated by the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and a further study of the fluorescence decay of this probe has been performed by multifrequency phase and modulation fluorometry. DPH fluorescence polarization is significantly increased in the membranes prepared from the youngest fraction of erythrocytes, indicating a decreased fluidity without any significant change in DPH fluorescence decay.

Erythrocyte Aging↗

PubMedDate not supplied

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.

Animals↗

PubMedDate not supplied

Plasma membrane fluidity and polarity of polymorphonuclear leukocytes from children with type I diabetes mellitus.

Polymorphonuclear leukocytes (PMN) from diabetic subjects have been found to be abnormal in various functional activities. These activities are mediated by the plasma membrane. This study was designed to evaluate plasma membrane fluidity and polarity in children with type I diabetes mellitus using fluorescence spectroscopy. PMN membrane fluidity and polarity were assessed in a group of 32 diabetic children. Membrane fluidity was investigated by measuring steady-state fluorescence anisotropy and fluorescence decay of 1-[4-trimethylammonium-phenyl]-6-phenyl- 1,3,5-hexatriene (TMA-DPH), whereas membrane polarity was studied by measuring the steady-state fluorescence emission and excitation spectra of 2-dimethylamino[6-lauroyl]-naphthalene (Laurdan). TMA-DPH and Laurdan are known to be incorporated at the hydrophobic-hydrophilic interface of the bilayer. Our data show a significant increase in steady-state fluorescence anisotropy in diabetic PMN that reflects a decrease in membrane fluidity, and a decrease in TMA-DPH lifetime distribution indicating a decrease in membrane heterogeneity. Laurdan shows a blue shift of the fluorescence emission and a red shift of the excitation spectra in diabetic PMN with respect to the control group, indicating a decrease in membrane polarity. The results demonstrate a decrease in the phospholipid order at the membrane surface and a decrease in membrane polarity in diabetic PMN. These alterations in the physico-chemical properties of the plasma membrane could be the basis of the modifications in functional activities of PMN. The changes in the plasma membrane of PMN could be the result of metabolic and chemical modification associated with type I diabetes.

Adolescent↗

PubMedDate not supplied

Effect of oral administration of bacterial extracts on the bactericidal capacity of polymorphonuclear leucocytes in children with recurrent respiratory infections.

The effect of orally administered bacterial extracts given intermittently over 16 weeks on the bactericidal capacity of polymorphonuclear leucocytes (PMNs) in children with recurrent respiratory infections was investigated using a luminol-amplified chemiluminescence assay. Chemiluminescence of PMNs stimulated with zymosan or N-formyl-methionyl-leucyl-phenylalanine (fMLP) before and after treatment with bacterial extracts or intramuscular benzanthine penicillin was evaluated. Chemiluminescence induced by opsonized zymosan increased significantly (P less than 0.05) after treatment with bacterial extracts, whereas no significant changes were observed in the fMLP-stimulated PMNs. Long-acting penicillin treatment did not significantly affect zymosan- or fMLP-stimulated chemiluminescence. The data suggest that orally administered bacterial extracts can increase the opsonic capacity of serum and thus the bactericidal capacity of PMNs in subjects with recurrent respiratory infections.

Adjuvants, Immunologic↗

PubMedDate not supplied

[Fryns syndrome. Description of a case].

We report on a female infant who presents a pattern of malformations including dysmorphic facies, Dandy-Walker anomaly, hypoplasia of the upper lobe of the right lung, associated with diaphragmatic elevation and slight digital anomalies. This whole clinical picture allows us to formulate the diagnosis of Fryns syndrome; this is one of the very few not lethal cases that are reported in literature.

Abnormalities, Multiple↗

PubMedDate not supplied

[Protective effect of oxatomide in infantile bronchial asthma. Double-blind study vs placebo].

BACKGROUND: This study has been designed to assess the protective effect of oxatomide in allergic bronchial asthma of the seasonal type in young children. METHODS: The study was carried out in a paediatric clinic; sixteen children divided into two balanced groups took oxatomide in an oral suspension at the dosage of 1 mg/kg/day, or placebo for a period of 2 months. Eight patients (7 males, 1 female), aged 22 months +/- 2.83 (mean +/- SD) took oxatomide in an oral suspension at the dosage of 1 mg/kg/day, while the other eight (3 males, 5 females; 22.13 months +/- 3.48) took placebo. Efficacy was assessed by monitoring cough, dyspnea at rest, dyspnea following exercise, wheezing, sleep disorders at baseline and after 15, 30 and 60 days of treatment, on the basis of a semiquantitative scale. All side effects were recorded. RESULTS: Persistent coughing was significantly reduced (p < 0.05) after two weeks' treatment with oxatomide. Sleep disorders and other symptoms remarkably improved. Dyspnea at rest and following exercise disappeared after 15 days' therapy, while the intensity of wheezing decreased after 30 days' active treatment. In all parameters examined, oxatomide was significantly more active than placebo at the first examination (p < 0.05 and p < 0.01). Oxatomide was well tolerated and only 2 patients complained of drowsiness which required a reduction in dosage. CONCLUSIONS: Oxatomide, at the dose of 1 mg/kg/day, obtained a good control of respiratory symptoms.

Anti-Asthmatic Agents↗