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Biomedical subjects

M Gros

Publications and source records attributed to M Gros.

At least 19 recordsLinked to original sources
PubMed2000

Asymmetrical labeling of giant phospholipid vesicles.

The method for labeling of inner membrane leaflet in unilamellar giant POPC vesicles was developed and characterised. Symmetrically NBD-PC labeled vesicles were treated by sodium dithionite, which undergoes an irreversible chemical reaction with NBD-PC molecule making it non-fluorescent. After the addition of dithionite the fluorescence on single vesicles as well as on vesicle suspension showed a 50% decrease of its initial value corresponding to marker quenching in the outer leaflet. Hence, fluorimetry as well as fluorescence microscopy prove that dithionite quenching is a suitable method to induce an asymmetrical labeling of the NBD-PC marked giant vesicles.

4-Chloro-7-nitrobenzofurazan↗
PubMed2000

Effect of pH on red blood cell deformability.

The effect of pH on the red blood cell (RBC) deformability, which is a consequence of a change of cell membrane elastic properties is studied experimentally. With the intention to reduce the effects on deformability of cell geometry and cytoplasmic viscosity, we measured the deformability of the cells with the same volume at various pH of cell suspension from 6.2 to 8.0. Constant cell volume was achieved by varying osmolarity. Deformability was quantified by measuring the elongation of RBCs subjected to velocity gradient in a transparent cone-plate rheoscope. Observed significant decrease of deformability at lower pH leads to the conclusion that membrane elastic properties could be affected by pH changes in the range from 6.2 to 8.0.

Cell Size↗
PubMed1996

Pre-Main-Sequence Star Candidates in the Bar of the Large Magellanic Cloud

Candidate pre-main-sequence stars were observed in the bar of the Large Magellanic Cloud during the search for dark matter in the galactic halo. Seven blue stars of apparent visual magnitude 15 to 17 had irregular photometric variations and hydrogen emission lines in their optical spectra, which suggested that these stars are pre-main-sequence stars of about 10 solar masses. These stars are slightly more massive and definitely more luminous than are Herbig AeBe pre-main-sequence stars in our own galaxy. Continued observations of these very young stars from another galaxy, which are probably at the pre-hydrogen-burning stage, should provide important clues about early stages of star formation.

Journal Article↗
PubMed1996

Low pH induced shape changes and vesiculation of human erythrocytes.

Shape changes and vesiculation were induced in intact human erythrocytes by gradually decreasing pH in the cell suspension. A sequence of different shapes preceding vesiculation was documented, i.e. discocytes, stomatocytes, and stomatoacantocytes. The final state was characterized by spherical mother cells and vesicles released. Low pH-induced vesiculation was also studied in the presence of stomatocytogenic or echinocytogenic compounds. The action of stomatocytogenic compounds was inhibitory, and echinocytogenic compounds had no effect on low pH-induced vesiculation. Vesiculation induced by low pH was studied also in isotonic solutions of different sucrose/salt composition. It was concluded that (i) low intracellular pH is responsible for cell shape transformations as well as for release of vesicles, (ii) at temperature 37 degrees C the intracellular pH value which induces the release of vesicles is 5.4, and (iii) the sequence of typical shape changes preceding vesiculation does not include echinocytes. The results are discussed on the basis of the layered membrane model of the shape formation and shape transformations of the human erythrocyte, and additionally considering the partial detachment of the membrane skeleton from the bilayer part of the membrane.

Erythrocyte Membrane↗
PubMed1990

Oxygen free radical scavenger system intermediates in essential hypertensive patients before and immediately after sublingual captopril administration.

Oxygen-free radical intermediates/scavengers were measured in 43 patients with essential hypertension who, although under antihypertensive therapy (without angiotensin-converting enzyme inhibitors), still had high blood pressure values. Measurements were taken before and 30, 60 and 120 min after sublingual administration of 25 mg captopril. Both systolic and diastolic blood pressures were reduced significantly. Twenty normotensive healthy volunteers were used as controls. The hypertensive patients had lower glutathione peroxide activity (GSHPx), higher superoxide dismutase (SOD) and serum glutathione reductase activity (GSHRx) compared with the controls. After captopril (30, 60 min) the glutathione and GSHPx increased compared with the pretreatment values. SOD and GSHRx remained high compared with the controls, while whole blood glucose-6-phosphate dehydrogenase remained low. Another group of 19 essential hypertensive patients, free of any antihypertensive medication (for at least 3 weeks), had lower GSHPx, SOD and higher GSHRx than the normal control group. Our results show significant differences in the oxygen free radical scavenger system of hypertensives compared with the normal subjects. It may be that captopril has a concomitant scavenging action together with its antihypertensive effect. Our study raises the question whether cell/organ damage will occur in hypertensive patients exposed to oxidative stress during periods of low antioxidative capacity.

Adult↗
PubMed1981

The use of oesophageal pH-monitoring for the evaluation of gastrooesophageal reflux after resection of the cardia and total gastrectomy.

We intended to estimate the applicability of oesophageal pHmetry for the evaluation and diagnosis of reflux oesophagitis after resection of the cardia and total gastrectomy. We applied the system of glass calomel electrode type GK 282 C (Radiometer-Kopenhagen). The pH probe was introduced transnasally in the remnant of the stomach or into the jejunum. Its position was controlled by fluoroscopy. Then the probe was drawn for 5 cm subsequently to the final position of 5 to 10 cm above the oesophagogastric or oesophagojejunal anastomosis. During the examination the patients were sitting or lying backward. Afterwards the reflux was provocated by Valsalva's and Müller's maneuvers and in head down position. If necessary the patient swallowed 50 cc. of 0,1 N HCl solution. We examined 37 patients. Among 29 patients after gastrooesophageal resection the reflux was stated in 18 cases (in 6 cases faint in 3 moderate and in 9 severe). The proof of the reflux failed in all 8 cases after total gastrectomy. In these cases the method is unsuitable for the evaluation of jejunooesophageal reflux because of a too fast passage of the swallowed 0,1 N HCl solution through the jejunum. It prevents the creation of the necessary acidity gradient between the oesophagus and the jejunum during the examination. We proved by this method the reflux in 14 out of 24 patients with regurgitation in the history and in 4 out of 11 without it. We consider the method to be safe, simple and successful in the assessment of gastrooesophageal reflux which must be evaluated in combination with the results of clinical, X-ray and endoscopical examinations.

Cardia↗