Biomedical subjects

A Kantar

Publications and source records attributed to A Kantar.

At least 19 recordsLinked to original sources

PubMed1998

Antioxidant activities of different hemoglobin derivatives.

The antioxidant activity of hemoglobin was examined by studying both its peroxidase activity and its interaction with the superoxide anion. The peroxidase activity of both the subunits (alpha and beta) was reduced with respect to the alpha 2 beta 2 tetramer and heme-oxidation was found to be associated with a decrease in this activity. Lucigenin-amplified chemiluminescence experiments have shown that at low pH, the presence of hemoglobin reduces the level of superoxide anion generated by the xanthine/xanthine oxidase system (met-Hb is more efficient in reducing the level of O2- than oxy-hemoglobin). These results confirm that hemoglobin may be of importance in providing protection against oxidative damage to erythrocytes.

Acridines↗

PubMed1998

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.

Adolescent↗

PubMed1996

Platelet plasma membrane in subjects with primary nocturnal enuresis: effect of desmopressin.

Plasma membrane fluidity of platelets (PLT) obtained from subjects with primary nocturnal enuresis (PNE) and healthy controls was investigated before and after addition of desmopressin (DDAVP). Membrane fluidity was studied by measuring steady-state fluorescence anisotropy of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3, 5-hexatriene incorporated into PLT plasma membrane. Our results show an increase in membrane fluidity at the surface level of PLT from subjects with PNE. Moreover, the addition of DDAVP induces a stable and significant decrease of membrane fluidity in both groups. These results suggest alterations of the lipid order in the exterior part of the PLT plasma membrane from patients with PNE.

Adolescent↗

PubMed1995

Effect of inhaled nedocromil sodium therapy on blood gas changes in children challenged with ultrasonically nebulized distilled water. A comparison of 8 mg versus 16 mg daily dose.

Changes in time course of blood partial pressures of oxygen (PtcO2) and carbon dioxide (PtcCO2) before, during and after challenge with ultrasonically nebulized distilled water (UNDW) were evaluated in 22 children with mild asthma in basal conditions, and after 8 weeks of therapy with inhaled nedocromil sodium at a daily dosage of 8 or 16 mg. PtcO2 and PtcCO2 were followed using transcutaneous O2 and CO2 monitoring system. All asthmatic subjects presented a significant decrease in PtcO2 and/or PtcCO2 (> 20% basal value) during or after challenge. After therapy, the decrease in PtcO2 and PtcCO2 was normalized in the group treated with 16 mg/day, whereas only a partial yet significant reduction in the decrease of O2 and CO2 was observed in the group assuming 8 mg/-day. These data indicate that inhaled nedocromil is effective in treating bronchial hyperresponsiveness in childhood and that the dose required to achieve this effect is of 16 mg/day.

Administration, Inhalation↗

PubMed1994

Polymorphonuclear leukocyte-generated oxygen metabolites decrease beat frequency of human respiratory cilia.

We investigated the effect of polymorphonuclear leukocyte (PMN)-generated oxygen metabolites on the ciliary beat frequency. PMNs were incubated with human respiratory cilia obtained by nasal brushing. The oxidative metabolism was stimulated by opsonized zymosan, and ciliary beat frequency was evaluated before and after activation of PMNs. Ciliary beat frequency was studied using video microscopy. Our results demonstrate a significant decrease in ciliary beat frequency after activation of PMNs. This effect was reduced by catalase. These data suggest that the PMN-generated oxygen metabolites, particularly H2O2, decrease beat frequency of human respiratory cilia.

Ascorbic Acid↗

PubMed1994

A sensitive detection of neutrophil activation by fluorescence quenching of membrane inserted singlet oxygen probe.

Fluorescence emission intensity of 1,3-diphenylisobenzofuran incorporated in polymorphonuclear granulocytes plasma membranes was investigated in basal conditions and during stimulation with different activators. Phorbol myristate acetate, known as the most effective "oxygen burst" inducer, produced a larger decrease in 1,3-diphenylisobenzofuran fluorescence intensity than 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activating factor) and N-formyl-methionyl-leucyl-phenylalanine, known as weak stimulants of oxygen uptake. Diphenyl iodonium an inhibitor of leukocyte NADPH oxidase, and the singlet oxygen selective trap alpha-terpinene inhibited the quenching effect of phorbol myristate acetate on 1,3-diphenylisobenzofuran fluorescence. These data suggest formation of singlet oxygen in activated leukocytes and demonstrate that measurement of 1,3-diphenylisobenzofuran fluorescence intensity provides a new sensitive method of detection of neutrophils activation.

Benzofurans↗

PubMed1994

Respiratory distress in a newborn with primary ciliary dyskinesia, situs inversus and Turner syndrome.

A report is given of a newborn girl with situs inversus and Turner syndrome that presented respiratory distress. The patient had a mosaic karyotype 45,X/46,X + mar (80%/20%). Ciliary motion analysis demonstrated a total absence of ciliary motion whereas, ultrastructural studies revealed typical features of primary ciliary dyskinesia (PCD) (absence or short outer/inner dynein arms in 90% of the cilia). We regard this rare combination (PCD, situs inversus and Turner syndrome) as a coincidental occurrence.

Chromosome Aberrations↗

PubMed1994

Successful interferon gamma therapy in a patient with X-linked chronic granulomatous disease, McLeod syndrome and hyper-IgE. Case report.

Recent studies have shown clinical benefit resulting from recombinant interferon gamma (rIFN-gamma) therapy in patients affected by chronic granulomatous disease (CGD), which represents an important adjunct to conventional therapy. In order to evaluate the effect of interferon gamma therapy, we investigated clinical and haematological parameters in a child with X-linked CGD, McLeod phenotype (kell negative) and hyper-IgE, before and after 8 months of therapy. Our results show no significant effect of rIFN-gamma on the respiratory burst of peripheral polymorphonuclear leukocytes. This notwithstanding, we observed improved clinical and haematological conditions. These results support the view that interferon gamma may benefit these subjects by influencing oxygen-independent antimicrobial activity or other immunological parameters.

Amoxicillin↗

PubMed1993

Effect of PAF on human lymphocyte membranes: a fluorescence study.

We have studied the effect of platelet-activating factor (PAF) on the physico-chemical organization of human lymphocyte plasma membranes by measuring the steady-state fluorescence anisotropy and the fluorescence decay of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated in lymphocyte 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 PAF antagonist L-659,989. The results indicate that the observed changes in the physico-chemical properties of the lymphocyte plasma membranes may be attributed to a PAF-receptor interaction.

Cell Membrane↗

PubMed1993

Use of Laurdan fluorescence in studying plasma membrane organization of polymorphonuclear leukocytes during the respiratory burst.

The changes in plasma membrane polarity of polymorphonuclear leukocytes (PMN) during the activation of the respiratory burst were investigated by measuring the steady-state fluorescence emission spectra of 2-dimethylamino(6-lauroyl) naphthalene (Laurdan), which is known to be incorporated at the hydrophobic-hydrophilic interface of the bilayer, displaying spectral sensitivity to the polarity of its surroundings. Laurdan shows a marked steady-state emission blue shift in nonpolar solvents, with respect to polar solvents. Our results show a blue shift of the fluorescence emission spectra of Laurdan during activation of PMN with phorbol myristate acetate or N-formyl-methionyl-leucyl-phenylalanine. These results suggest that the activation of the respiratory burst of PMN is accompanied by a decrease in polarity in the hydrophobic-hydrophilic interface of the plasma membrane.

2-Naphthylamine↗

PubMed1993

Membrane fluidity of polymorphonuclear leukocytes from children with primary ciliary dyskinesia.

Plasma membrane fluidity and heterogeneity of polymorphonuclear leukocytes (PMN) were investigated in seven children with primary ciliary dyskinesia (PCD) and 17 healthy controls. Membrane fluidity and heterogeneity were studied by measuring the steady state fluorescence anisotropy and fluorescence decay of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) incorporated into PMN plasma membrane. Our results show an increase in membrane fluidity at the surface level of PMN from patients with PCD. Distribution analysis of TMA-DPH lifetime values indicate an increase in membrane heterogeneity in subjects with PCD. The observed changes in the physicochemical properties of the membrane could lead to alterations in the function of PMN from children with PCD.

Chemotaxis, Leukocyte↗

PubMed1993

[Oxidative metabolism in polymorphonuclear granulocytes of children with trisomy 21].

In response to certain stimuli, polymorphonuclear leukocytes (PMNs) undergo an oxidative burst during which a series of reactive oxygen metabolites are generated. The importance of the release of these oxygen metabolites by polymorphonuclear leukocytes, is recognized to be a key event in the function of these cells during infection and inflammation. We have evaluated the release of reactive oxygen species during the activation of respiratory burst (RB) of PMNs obtained from children with trisomy 21 using chemiluminescence techniques. As chemiluminogenic probes we have employed lucigenin and luminon that are know to be sensitive to the superoxide anion and the H2O2-myeloperoxidase-halide system of PMNs, respectively. Activated PMNs from children with trisomy 21 exhibited a low level of superoxide and a reduced activity of H2O2-myeloperoxidase-halide system compared to the control group. No significant difference in extracellular H2O2 release was observed. It seems likely that alterations in the enzymatic activities of the Cu/Zn-Superoxide dismutase and myeloperoxidase induce imbalance in the release of reactive oxygen species in activated PMNs from children with trisomy 21. This imbalance could be on the basis of the increased oxidative injury reported in trisomy 21.

Child↗

PubMed1992

Cilia in children with recurrent upper respiratory tract infections: ultrastructural observations.

We investigated the ultrastructure of nasal cilia in 27 children suffering from recurrent infections of the upper respiratory tract, during and after the onset of an acute respiratory infection, and after a convalescent period of 12 weeks. Our results demonstrated that in seven subjects after resolution of infection, the morphology of a large proportion of the cilia (32%) was not back to normal. These findings suggest a long-term residual effect of infection, or the inability to reestablish normal ciliary structure during the convalescent period in some subjects with recurrent upper respiratory tract infection.

Acute Disease↗

PubMed1992

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.

Acetylcholinesterase↗

PubMed1992

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.

Adolescent↗

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↗