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At least 253 records · Page 14Linked to original sources
PubMed2001

[The metabolism of trehalose and intracellular glycerol in Candida krusei responding to high osmosis].

The trehalose and intracellular glycerol contents of osmotolerant yeast Candida krusei cells rapidly increased in response to the medium containing NaCl. Addition of NaCl at early exponential phase or steady phase increased trehalose content only, but the content of extracellular glycerol increased gradually. Development of resistance was accompanied by accumulation of trehalose and was apparently unrelated to intracellular glycerol content which was always low under these conditions. There seems to be an overlap function between trehalose and glycerol in Candida krusei cells in response to the osmotic conditions.

Candida↗
PubMed2005

[The comparison study on the preparation of chromosomes of the freshwater prawn Macrobrachraium nipponense (Crustacea, Decapoda)].

The Chromosomes of Macrobrachium nipponense had been prepared using the materials of testis or embryo with the chromosome low-osmosis method or cell low-osmosis method. After 5.5 h, the bivalents at meiotic diplotene were appeared. The comparison of the two methods for two different materials showed that the morpha of the chromosome of testis using the low-osmosis method was better than that of using the cell low-osmosis method. Contrarily, the low-osmosis was better than the cell low-osmosis for the morpha of the chromosome of embryo. The bivalents at meiotic diplotene were rod-shaped, and centromere position could be identified easily at that time. The diploid chromosomes numbers were 104. The chromosome formula was N=11M+26SM+4ST+11T. The technique of the chromosome preparation of Macrobrachium nipponense was preliminarily discussed as well.

Animals↗
PubMed1999

Quality of water used for haemodialysis: bacteriological and chemical parameters.

BACKGROUND: The bacterial and chemical contamination of dialysate fluids are important problems in haemodialysis therapy and may be caused by the water used for dialysate preparation. METHODS: We performed a survey of the microbiological and chemical quality of the water used in seven dialysis wards. Special attention was paid to the effects of each water treatment step, for example ion exchange, reverse osmosis and UV disinfection, on the number of bacteria (measured as colony forming units, CFU), the amount of endotoxin (endotoxin units, EU) and various chemical parameters, the main focus being on calcium, magnesium, sulphate, aluminium and heavy metals. RESULTS: CFU values exceeding the European Pharmacopeia value, determined at an incubation temperature of 22 degrees C, were found in the samples of raw water (20.0%, n=25), after ion exchange (66.7%, n=12), after reverse osmosis (33.3%, n=18) and also in samples of the dialysis water taken at the inlets (12.5%, n=40) and outlets (50.0%, n=18) of the machines. Whereas all raw water samples from the wards showed high mean values for endotoxin (0.56-9.10 EU/ml) and the endotoxin levels were often enhanced after ion exchange (0.13- >9.49 EU/ml), treatment by reverse osmosis led to a satisfactory decrease in endotoxin in all samples (<0.03 EU/ml). Sufficient reductions in calcium, magnesium and sulphate could only be achieved by the combined application of ion exchange and reverse osmosis. Mercury contamination was observed in the samples after ion exchange at three treatment plants, this was possibly caused by polluted regenerants. Increased amounts of aluminium, copper and zinc were found in water samples from different sites in the treatment systems and were caused by materials in contact with the water. CONCLUSIONS: A sufficient chemical water purification treatment system should consist of ion exchange and reverse osmosis. Attention has to be paid to the suitability of materials in contact with the water and of the chemicals used, for example regenerants or corrosion inhibitors. From the microbiological point of view, a safety UV disinfection step in the water-treatment system is favourable. To avoid bacterial recontamination periodic cleaning and disinfecting of the water-treatment and distribution systems, as well as the dialysis machine are essential. There is the need for complete guidelines regarding dialysis water that include all relevant chemical and microbiological parameters. Based on this standard, periodic examination of the water after each treatment step has to be performed.

Metals↗
PubMed1970

An electrokinetic model of transduction in the semicircular canal.

Transduction in the semicircular canal was studied by focusing an infrared beam on either side of exposed ampullae from the posterior canals of Rana pipiens. The direction of fluid movement resulting from a stimulus was inferred by observing the polarity of the change in afferent impulse mean rate relative to the spontaneous value. On the basis of the accepted functional polarization of this receptor, the results indicate that fluid moved toward the warmer side of the ampulla. Convection and thermal reception were shown to be unlikely explanations for these results. Morover, cupular displacements toward the warmer side would not be expected. Because thermo-osmosis can cause fluid to move toward the warmer side in a gelatin membrane, the results can be interpreted as evidence that thermo-osmosis occurred in the gelatinous cupula and influenced the transduction mechanism. Thermo-osmosis of liquids appears to be due to an electric field that is set up in a charged membrane; hence, the hair cells might have detected an electric field that occurred in the cupula during thermo-osmosis. Electroreception might be an important link in the transduction of physiological stimuli also. Rotational stimuli could result in weak electric fields in the cupula by the mechanoelectric effect. Cupular displacements could be important for large stimuli, but extrapolations to threshold stimuli suggest displacements of angstrom amplitudes. Therefore, electroreception by the hair cells could be an explanation of the great sensitivity that has been observed in the semicircular canal and other labyrinthine receptors.

Animals↗
PubMed1997

A triphasic analysis of negative osmotic flows through charged hydrated soft tissues.

Osmotic flow and ion transport in a one-dimensional steady diffusion process through charged hydrated soft tissues such as articular cartilage were analysed using the triphasic theory (Lai et al., 1991, J. biomech. Engng 113, 245-258). It was found that solvent would flow from the high NaCl concentration side to the low concentration side (i.e. negative osmosis) when the fixed charge density within the tissue (or membrane) separating the two electrolyte (NaCl) solutions was lower than a critical value. The condition for negative osmosis was derived based on a linear version of the triphasic theory. Distributions of ion concentration and strain field within the tissue were calculated numerically. Quantitative results of osmotic flow rates (ordinary and negative osmosis), ion flux and electric potential across the tissue during this diffusion process suggest that the negative osmosis phenomenon is due to the friction between ions and water since they could flow through the tissues at different rates and different directions.

Biomechanical Phenomena↗
PubMed2004

Frequency bandwidth limitation of external pulse electric field in microchannels. Applications to analyte velocity modulation detections.

Pulse field driven electro-separations have been used for different analytical advantages, such as signal quality improvement and separation performance improvement. We have studied the temporal electro-osmosis in microchannels due to viscous diffusivity under the external pulse electric fields. Theoretical studies derived from Navier-Stokes equations conclude the dependence of the time to steady state electro-osmosis on the channel sizes. Pulse field frequency should be limited by the electro-osmosis setting-in time. We also observed the unstable electro-osmosis as the external field frequency increases. As channel geometry characterization results are employed in the mathematical models, the threshold frequencies obtained in experimental data are consistent with the computational predictions. In previous studies, effective signal quality improvement of electro-separations has been demonstrated, when external pulse fields modulate analyte velocities with synchronous lock-in detection. The results indicate signal-to-noise ratio improvement would be more significant at the high frequency regime where flicker noise is not dominant. Since bandwidth limitation due to fluid viscosity constrains the pulse frequency, optimum analyte velocity modulation is in need of further investigation. Under the bandwidth constrains, we have investigated the theoretical optimum modulation frequencies.

Computer Simulation↗