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V V Morariu

Publications and source records attributed to V V Morariu.

18 recordsLinked to original sources
PubMed2005

Influence of near null magnetic field on in vitro growth of potato and wild Solanum species.

The influence of near null magnetic field on in vitro growth of different cultures of potato and related Solanum species was investigated for various exposure times and dates. Potato (Solanum tuberosum L. cv. Désirée) in vitro cultures of shoot tips or nodal segments were used. Three different exposure periods revealed either stimulation or inhibition of root, stem, or leaf in vitro growth after 14 or 28 days of exposure. In one experiment the significant stimulation of leaf growth was also demonstrated at biochemical level, the quantity of chlorophyll a and b and carotenoids increasing more than two-fold. For the wild species Solanum chacoense, S. microdontum, and S. verrucosum, standardized in vitro cultures of nodal stem segments were used. Root and stem growth was either stimulated or slightly inhibited after 9 days exposure to near null magnetic field. Callus cultures obtained from potato dihaploid line 120/19 were maintained in near null magnetic field in 2 different months. For these experiments as well as for Solanum verrucosum, callus cultures recorded either slight inhibition or no effect on fresh weight. For all experiments significant growth variation was brought about only when geomagnetic activity (AP index) showed variations at the beginning of in vitro growth and when the explant had at least one meristematic tissue. Moreover longer maintenance in near null magnetic field, 28 days as compared to 14 days or the controls, can also make a difference in plant growth in response to geomagnetic field variations when static component was reduced to zero value. These results of in vitro plant growth stimulation by variable component of geomagnetic field also sustain the so-called seasonal "window" effect.

Cell Proliferation↗
PubMed1999

Pore resealing inactivation in electroporated erythrocyte membrane irradiated with electrons.

The changes in the electroporation process of human erythrocytes membrane due to the direct action of high energy electron radiation were investigated. To avoid the indirect effects caused by radiolytic products of water, the irradiation was performed at liquid nitrogen temperature. The irradiated cells have been exposed to square-wave electric pulses at 4 degrees C in isotonic suspensions to induce membrane electropores. The pores resealing were quantified by monitoring the cell hemolysis. A significant decrease of the resealing process was found for irradiation doses higher than 100 Gy. The mass of molecular structures affected by the direct action of radiation was estimated using the target analysis method. We found a molecular weight Mm approximately 930 kDa roughly corresponding to spectrin tetramer of the cytoskeleton. This suggests that spectrin network plays an important role in the pores resealing of the electropermeabilized erythrocyte membrane.

Cell Membrane Permeability↗
PubMed1998

The effect of gamma radiation on Li+ transport through human erythrocyte membranes.

Human erythrocytes were exposed at room temperatures to 662 keV gamma radiation at doses up to 60 Gy. The total delta Li+ influx as well as the delta Li+ influx by passive diffusion and Na(+)-K+ pump mechanisms increased linearly with the dose. The rate constant K of Li+ efflux by the Li(+)-Na+ countertransport mechanism through irradiated erythrocyte membranes was reduced by about 35% at the highest dose.

Cell Membrane↗
PubMed1997

Manganese transport through human erythrocyte membranes. An EPR study.

Manganese uptake by human erythrocytes was investigated in the concentration range 0.5-20 mM in the suspending solution, by using the EPR technique. S shaped dependencies of manganese influx on manganese doping solution concentration for both fresh and vanadate treated erythrocytes were found, with maximum influx values of 4.1 +/- 1.9 x 10(-10) mol/m2 x s and 2.1 +/- 0.3 x 10(-9) mol/m2 x s, respectively. At low manganese concentrations (< 2 mM) the manganese permeability coefficient increases with increasing the doping concentration, the ions cooperate for achieving a transport event. For high manganese concentration (> 5 mM) the permeability coefficient decreases with increasing the doping concentration, the ions competing for the limited amount of transport system. A similar increase in manganese uptake as in vanadate treated erythrocytes was measured for 'in vitro' aged erythrocytes. These results might suggest that human erythrocytes possess an active transport mechanism by which, they oppose to manganese influx. This hypothesis is also supported by the 10-15 min time lag between the moment of doping and the start of the manganese influx into the fresh erythrocytes. The manganese uptake inhibition by nifedipine, a calcium channel blocker, for the case of vanadate treated erythrocytes, suggests that, at least partially, manganese uptake by the cells occurs via the 'calcium channels'.

Biological Transport, Active↗
PubMed1996

Fluctuations in red cell membranes.

Acetylcholinesterase activity and molecular groups characteristic of erythrocyte ghost membrane proteins show significant circadian oscillations over 24 h. These fluctuations were previously interpreted as very slow oscillations with a period ranging between 1.3 and 1.6 h. Autocorrelation function analysis revealed that practically all data represented correlated noise which was characterized by an integral time scale of about 3-4 h. The meaning of this characteristic time is proposed in terms of an analogy with hydrodynamic turbulence. The fluctuations seem to be sensitive to the type of protein involved, the protease and Triton-X treatment, respectively. This suggests that fluctuations may offer information about the slow dynamics of the membranous proteins.

Acetylcholinesterase↗
PubMed1995

The effects of near null magnetic field upon the leucocyte response in rats.

Wistar rats were kept for 2 and 4 weeks in conditions of near null magnetic field. The total serum proteins, lipids and glucides, as well as the leucocyte and neutrophil counts showed no significant changes against controls kept in natural magnetic field conditions. A significant monocytosis, a decrease in the circulating phagocyte count and in the phagocytic activity was noticed in null magnetic field. These results suggest that the natural magnetic field significantly influences health both on the ground and possibly in cosmic conditions.

Animals↗
PubMed1987

NMR investigation of the influence of procaine and its metabolites on the water exchange through human erythrocyte membranes.

The effect of procaine hydrochloride and its metabolites on the diffusional water exchange through erythrocyte membranes was investigated at 37 degrees C and at concentrations ranging between 5 X 10(-5) M and 5 X 10(-1) M by using the NMR manganese doping method. Procaine hydrochloride and 2-diethylaminoethanol have a moderate stimulating effect on the water exchange, of up to 20% at concentrations ranging between 10(-3) and 10(-2) M, while an increasing inhibitory effect was found at higher concentrations. The p-aminobenzoic acid has no effect on the water exchange up to 10(-2) M and, at higher concentrations, and apparent decreasing inhibition was noticed which is thought to be an artefact due to the uptake of Mn2+ by the cells. The temperature dependence studies suggest that procaine HCl enhances the uptake of Mn2+ by the cells. An opposite effect was found for rigid erythrocytes. The p-aminobenzoic acid and 2-diethylaminoethanol appeared to be more effective than procaine hydrochloride in increasing the uptake of Mn2+.

4-Aminobenzoic Acid↗
PubMed1986

The uptake of manganese ions and the apparent thermal transition of the erythrocyte membranes.

The nuclear magnetic resonance manganese doping technique is currently used for the determination of the water diffusional exchange time through human erythrocyte membranes. An apparent thermal transition at 26 degrees C was noticed at 18-30 mM manganese doping in the suspending solution. An analysis in terms of a two-phase nuclear spin exchanging system revealed that apparent thermal transitions are expected to occur in the upper and lower temperature regions. They represent a shift from intermediate exchange rates where water diffusion through the membrane is dominant to either fast or slow exchange rates where proton relaxation is the controlling process. The lower temperature apparent transition may be altered by the intracellular manganese concentration; the lower the Mn2+ concentration the lower the transition. Also according to this interpretation only a fraction of the erythrocytes are significantly permeated by Mn2+. The upper transition depends on the Mn2+ concentration in the extracellular volume; it decreases with decreasing Mn2+ concentration.

Chemical Phenomena↗
PubMed1986

Nuclear magnetic resonance investigation of erythrocyte membranes in chronic myeloproliferative disorders.

The temperature dependence of the apparent water diffusional exchange through erythrocyte membranes in cases of policitemia vera, chronic granulocytic leukemia and primary myelofibrosis was measured by using a nuclear magnetic resonance method in the presence of Mn2+. The thermal transition shifted to lower temperatures in all cases, regardless of the stage of the disease, suggesting a structural alteration of the membrane. The shift of transition indirectly suggests a lower penetration of the erythrocytes by Mn2+. The water exchange time at 37 degrees C also increased, mainly in the blast crisis; it seems to have a prognostic value of some clinical interest. No simple correlation of the water exchange and the following clinical investigations was observed: the white count, the percentage of promyelocites and myeloblasts, the sedimentation rate of blood, the osmotic fragility of erythrocytes, the total concentration of proteins, albumin and immunoglobulins, respectively, in plasma.

Diffusion↗
PubMed1985

Nuclear magnetic resonance investigation of human erythrocytes in the presence of manganese ions. Evidence for a thermal transition.

Water proton transverse relaxation was investigated in whole blood and washed erythrocytes samples, respectively, at various temperatures and manganese concentrations. Water diffusional exchange controls proton relaxation in whole blood samples at higher Mn2+ concentrations (20-30 mM) or in washed erythrocyte samples at low Mn2+ content (1-5 mM). Mn2+ uptake is significant in washed normal erythrocyte samples when its concentration is about 18 mM or higher in the medium, at temperatures below about 26 degrees C. The thermal transition as revealed by the NMR doping method represents a switch from a water exchange process, mainly seen in the higher temperature range, to a paramagnetic ion controlled water proton relaxation in the lower temperature range.

Erythrocyte Membrane↗
PubMed1981

Effects of temperature and pH on the water exchange through erythrocyte membranes: nuclear magnetic resonance studies.

The temperature and pH dependence of water exchange has been studied on isolated erythrocytes suspended in isotonic buffered solutions. At pH 7.4 a break in the Arrhenius plot of water exchange time at around 26 degrees C was found. The mean value of the apparent activation energy of the water exchange time at temperatures higher than that of the discontinuity was 5.7 kcal/mole (+/- 0.4); at lower temperatures the values of the apparent activation energy were below 1.4 kcal/mole. The pH dependence of water exchange time of isolated erythrocytes revealed a marked increase of the water exchange time values in the acid range of pH; a much smaller variation of the same parameter occurs between pH 7.0 and 8.0. These finding could be correlated with other processes involving erythrocyte membranes that showed similar pH and temperature dependence and were considered to indicate state transitions in the membranes. It is suggested that the temperature and pH effects on water diffusion indicate that conformational changes and cooperative effects are implicated in the mechanism of this transport process.

Adult↗
PubMed1980

Nuclear magnetic resonance at low temperatures in lyophilized and non lyophilized normal and tumoral tissues. III. Study of the solid--fluid interface.

Adsorption water on lyophilized and non-lyophilized, normal and malignant tumoral tissues was studied by nuclear magnetic resonance. Comparative study of variations in the proton signal amplitude (A) and the water proton line width (delta v) at temperatures within the 0 degree to --40 degrees C range showed: (a) The identical behaviour of the proton signal amplitude of water adsorbed on normal rat tissues (liver, skeletal muscle). (b) Similar behaviour of the amplitude in malignant tumoral tissues and hepatic embryonic tissue. (c) Dependence of the relative variation of the resonance line width at --25 degrees and --5 degrees C upon hydration of the sample suggested that there was no difference between malignant and normal tissues at the level of the macromolecular structure-adsorption water interface.

Animals↗
PubMed1978

Nuclear magnetic resonance investigation of the freezing of water in rat kidney tissues.

The proton linewidth and the integral of the absorption signal of water in rat kidney tissue have been measured at sub-zero temperatures. The water, fresh or stored at +4 degrees C for 24--48 h, shows a supercooling effect down to -10 degrees C to -14 degrees C. At -20 degrees C, 10--20% of the total tissue water remains unfrozen. The supercooling effect is diminished by prior storage at positive temperatures but completely eliminated by storage at several degrees below 0 degrees C. This suggests that the freezing behavior of tissue water varies with change in the physiological state of the tissue. Tissue samples stored at positive temperatures were observed to be more vulnerable than fresh tissue to freezing damage. Storage at several degrees below 0 degrees C for the same period of time appeared to be even more damaging.

Animals↗
PubMedDate not supplied

The effect of low temperatures on the viability of Ehrlich ascites tumor cells.

By using rapid freezing-rapid thawing procedures on Ehrlich ascites tumor cells the authors succeeded in maintaining the viability of these cells, ascertained by two methods: a) trypan blue dye-exclusion test, and b) grafting in experimental animals of cells maintained for three days at -80 degrees C.

Animals↗