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Biomedical subjects

B Gonet

Publications and source records attributed to B Gonet.

16 recordsLinked to original sources
PubMed2004

Capacity of ascorbyl palmitate to produce the ascorbyl radical in vitro: an electron spin resonance investigation.

This study aims to compare the electron spin resonance (ESR) spectra emitted by human blood loaded with either ascorbyl-6-palmitate (AP), a lipid-soluble derivative of ascorbic acid (AA), or with AA. Whole blood of a healthy male individual was equilibrated with equimolar concentrations of AP and AA of 200, 400, and 800 micromol/l. The intensity of the ESR signal, expressed as the peak-to-peak amplitude, reflects the amount of unpaired spins that are created due to the reducing action of AA and is proportional, in relative terms, to the amount of the ascorbyl radical formed. We found that the blood with AP emitted an ESR signal whose singlet shape, width, and location precisely correlate with the known characteristics of the ascorbyl radical in vitro. The signal magnitude increased linearly with increasing concentrations of AP and was similar to that of AA. We conclude that AP is biologically active, as it generates the ascorbyl radical, an action that also underlies the scavenging process by ascorbic acid. To this end, ascorbyl-6-palmitate might have potential advantages, due to its ability to penetrate biomembranes and to act at the lipid-related molecular target sites.

Adult↗
PubMed1998

Antioxidant status of children with steroid-sensitive nephrotic syndrome.

Eighteen children with steroid-sensitive nephrotic syndrome (SSNS) were studied. The control group comprised 20 healthy children. The following indirect parameters of reactive oxygen species activity were determined in nephrotic patients during four stages of the disease (full relapse before prednisone administration, disappearance of proteinuria, prednisone cessation, unmaintained remission): plasma malondialdehyde (MDA) levels, copper/zinc superoxide dismutase (CuZn SOD) activity and glutathione peroxidase (GPX) activity in erythrocytes, reduced glutathione (GSH) and vitamin C levels in whole blood, and vitamin E level in serum. Increased MDA levels, reduced vitamin C levels, and enhanced CuZn SOD activity were found in relapse. GSH concentration was high during all four stages. Vitamin E level was also increased, parallel to the pattern of serum lipids. GPX activity remained low during the proteinuria stage and in remission. We conclude that the majority of abnormal findings can be attributed to the hyperlipidemia of NS. Low GPX activity may be a factor limiting the antioxidant capacity in NS. The present study is inconclusive regarding the role of free radicals in the proteinuria of NS.

Adolescent↗
PubMed1997

Hypoxia depletes ascorbate in the cat carotid body.

Vitamin C or L-ascorbate is an effective endogenous reducing agent influencing the functions that are involved with the redox mechanism. Detection of oxygen tension changes by the carotid body chemoreceptors is one such function. In this study we investigated the hypothesis that the level of ascorbate, if present, could change in the carotid body as a result of ascorbate's interaction in the chemosensing process, which would be reflected in the production of the ascorbyl radical. We addressed this issue by examining changes of the ascorbyl radical, using the in vitro electron spin resonance spectroscopy (ESR), in the carotid bodies dissected from pentobarbitone anesthetized cats exposed in vivo to three eucapnic, breathing gas mixtures of different O2 concentration: normoxic, 21% O2; hypoxic, 7% O2; and hypoxic-reoxygenated, 7% O2 followed by 100% O2. Each group consisted of five cats, yielding five pairs of carotid bodies for the ESR signal recording. We found that the intensity of ESR signals, measured as peak-to-peak amplitude, was diminished by 39 and 43% in the hypoxic and hypoxic-reoxygenated groups, respectively, compared with that in normoxia. The study shows that ascorbate was present in the normoxic carotid body and was depleted by hypoxia. We conclude that ascorbate is part of free radical mechanisms operative in the carotid body in hypoxia.

Animals↗
PubMed1994

Free radical aspects of the ozone influence on blood.

Ozone is one of the most potent toxic agents. The noxious effects of its influence on living organisms appear mainly in the lungs and blood. A considerable role in its action is ascribed to free radicals. In this study the ESR method was applied to indirectly demonstrate the free radical effects, as well as the significance of ascorbate in ozonizing the blood. The effects of ozonizing the blood in vitro indicate the existence of a "local" protective mechanism of the blood cells, while in vivo they point out the consumption of ascorbate in "scavenging" of free radicals.

Administration, Inhalation↗
PubMed1992

Essential phospholipids modify immunological functions and reduce experimental atherosclerosis in rabbits.

Atherosclerosis was induced in male mongrel rabbits with a high-fat diet and the influence of essential phospholipids (EPL) on plaque formation, parameters of lipid metabolism and immunological functions was studied. When EPL were added to the high-fat diet there was a significant reduction in the area of atherosclerotic involvement of the aorta. The serum concentration of lipids decreased, often to normal values, and cholesterol esterified with polyunsaturated fatty acids appeared. Normalization of the malonyldialdehyde level in plasma was accompanied by a decrease in the concentration of ascorbate free radicals in blood and liver. The high-fat diet caused a depression of both non-specific and specific immune functions studied. With EPL in the diet the tests showed near normal or normal values. It is inferred from these results that a normal state of the immune system is important for preventing the progress of atherosclerotic changes. This is discussed with reference to the role of some immune cells in the metabolism of lipids and to participation of essential phospholipids in plasma membrane functions.

Animals↗
PubMed1991

Effect of a magnetic field on ascorbate system in mice.

The effect exerted on the ascorbate system due to the exposure of mice to the constant magnetic field associated with MRI methods has been examined. The mice were exposed to magnetic field 1.00 T strength for 0.2 h, 3 h, or 24 h. The ascorbyl free radical in tissues was measured in vitro, which in vivo corresponds to the level of ascorbic acid. Only in a group of mice where the ascorbyl free radical was measured 24 h following their exposure to magnetic field 1.00 T strength for 24 hours, was the level of free radical in tissues significantly decreased.

Animals↗
PubMed1985

Influence of constant magnetic fields on certain physiochemical properties of water.

There has been considerable recent interest in the question of effects of constant magnetic fields (CMF) on living organisms. The possible alteration of the physiochemical properties of water appears to be one example of such an influence. The dielectric constant, pH, and surface tension of water exposed to CMF action were studied. The results fail to confirm the changes observed by some authors. Controversial opinions on this problem are also summarized and discussed.

Hydrogen-Ion Concentration↗
PubMedDate not supplied

Solving problems fluorine 19F with NMR spectroscopy.

Fluorine 19F is one of few 'lucky' elements found in living organisms, whose nucleus is characterised by non-zero spin, which makes it possible to detect fluorine and to analyse (and image) its chemical compounds with the help of Nuclear Magnetic Resonance (NMR). Fluorine 19F spectroscopy is not as popular as that of hydrogen 1H or phosphorus 31P, however, this method has recently been developed and applied (in medicine, too) more and more frequently, despite technical problems. This paper is a brief introduction to the techniques of investigating fluorine 19F with NMR spectroscopy, providing insight into the peculiarities and the difficulties associated with this method. It is also a short review of the achievements in NMR fluorine investigations in the fields of biology and medicine.

Animals↗
PubMedDate not supplied

[Properties of hemoglobin in ozone-exposed hemolysates of erythrocytes].

The objective of the paper was to investigate the changes in haemoglobin properties under the influence of ozone on haemolysates of erythrocytes. The detailed analysis of experiments permitted to draw the following conclusions: 1. Haemoglobin in the presence of ozone is transformed into methaemoglobin in a biphasic process. 2. In ozone exposed haemolysates of erythrocytes the haemoglobin had other properties: an increase in affinity for oxygen and a decrease of the hem-hem interaction coefficient.

Erythrocytes↗