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Effect of antidiuresis on renal creatine metabolism

86%
The current work investigates whether creatine metabolism is involved in renal adaptation to dehydration. Wistar rats were either deprived of water or induced to drink water abundantly during 60 h. Cortical and medullar mRNA levels of Na+/Cl-/creatine transporter (CRT), l-arginine: glycine amidinotransferase (AGAT), guanidinoacetate methyltransferase (GAMT) and of the tonicity sensitive genes coding for aquaporin 2, Na+/Cl-/betaine transporter and glucocorticoid-inducible kinase were measured by real-time PCR assays. The activity of the CRT and that of Na+/-methyl-glucose transporter were evaluated in renal brush-border membrane vesicles. In water loaded animals, the mRNA levels of AGAT and CRT, and the activity of the CRT were greater in the cortex than in the medulla. GAMT mRNA levels were of similar magnitude and lower than those of AGAT mRNA. Dehydration decreased cortical and medullar AGAT and CRT mRNA levels and CRT activity and it did no affect GAMT mRNA abundance. These decreases were creatine specific because dehydration increased Na+/-methyl-glucose transporter activity and the mRNA abundance of aquaporin 2, Na+/Cl-/betaine transporter and glucocorticoid-inducible kinase. In conclusion, this is the first report showing that: i) the kidneys express significant amounts of GAMT mRNA, ii) dehydration down-regulates the expression of AGAT gene and iii) dehydration down-regulates CRT gene expression and activity.
Hydrate complexes of magnesium aspartate, magnesium aspartate glycinate, magnesium aspartate arginate have been synthesized and characterized by the elemental and spectral analysis. The formulae of the magnesium complexes were Mg(C4H6O4N) • 4H2O, Mg(C6H10O5N2) • 5H2O, and Mg(C10H19O5N5) • 7H2O. The main thermal process: dehydration of the complexes, was studied using the thermoanalytical methods: differential thermal analysis (DTA), thermogravimetric analysis (TG), and differential scanning calorimemtry (DSC) measurements. The influence of additional ligands (glycinate or arginate) introduced to the structure of magnesium aspartate on the physicochemical properties of the newly synthesized compounds was analysed.
The purpose of these studies was to determine how plasma levels of arginine vasopressin (pAVP) are related to workload, plasma osmolality (pOsm), blood volume (BV) and plasma angiotensin II (pAII) in exercising dogs. Measurements were made in dogs running on a treadmill at 7.5 km. hr⁻¹ at slopes of 0, 10% and 20% when they were hydrated ad lib and when they had been deprived of drinking water and also in dogs running on a 20% slope after an IV infusion of hypertonic NaCl. Dehydration increased pOsm by 6.6% and reduced BV by 10% in resting dogs. In dehydrated animals, pAVP, pAII and pOsm were elevated above hydrated levels at rest and during exercise at all three workloads. In hydrated dogs, pOsm rose during exercise at 10% and 20% slopes but pAVP rose above resting levels only at the highest workload and pAII was not affected by exercise. In dehydrated dogs, pOsm and pAVP rose during exercise at 10% and 20% slopes and pAII was elevated at the 20% slope. BV decreased during exercise at the highest workload in both hydrated and dehydrated animals. After hypertonic NaCl, pAVP rose during exercise but pOsm and pAII did not. The results suggest that both osmotic and nonosmotic factors contribute to the release of AVP in exercising dogs and that exercise leads to a leftward shift in the relationship of pAVP to pOSM which could be a result of reduced blood volume.
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The main aim of the research was to determine a susceptibility of a dried sludge to a rehydration increase. The paper presents the results of investigations for a sludge which had been dried to ca. 86% of dry mass and stored in an airy place under roof during 2.5 years. As well, trials were carried out for a completely dried sludge (0% of water), stored outside under roof as well as inside in a laboratory room. To determine a maximum level of humidity increase, the results of re-hydration increase were presented for a sludge stored in conditions of capillary ascent. Additionally, a density, porosity and bulk density were determined for the investigated sludge.
The effect of pressure on the efficiency of osmotic dehydration of apples was studied. It was found that at reduced dehydration pressure the water loss and solid gain increased with the molecular weight of solute. The dehydration at increased pressure resulted in higher water loss and solid gain when the solute used had lower molecular weight. The highest efficiency of dehydration was obtained during dehydration in starch syrup at reduced pressure.
Dehydrated hereditary stomatocytosis (DHS), also designated hereditary xerocytosis, is a chronic congenital haemolytic anaemia, underlain by abnormal transmembrane fluxes of Na+ and K+. The intracellular concentrations of Na+ and K+ are increased and decreased, respectively, though to various degrees. Stomatocytes and other abnormally shaped red cells appear on smears. The osmotic gradient ektacytometric curve is shifted leftward. Cell dehydration, macrocytosis and/or high reticulocyte counts are noted. Electrophoresis of membrane proteins is unremarkable and, in particular, stomatin is present. The inheritance pattern of DHS is invariably dominant, although the severity and even the nature of the symptoms may vary within some particular kindreds. DHS may be associated with hereditary pseudohyperkalaemia (HPHK) and/or perinatal oedema (PO), as has been recently discovered. HPHK, per se, is a lifelong asymptomatic trait characterized by a dramatic elevation of kalaemia when blood is allowed to stand for a few hours at room temperature. Its inheritance pattern is dominant. Modulation of expression within families has not been mentionned to date. PO one is dealing with here has the unique property of spontaneously receding after birth. We have screened a number of families with DHS in order to define the single or multiple facets of the clinical phenotype. We found cases with DHS alone, HPHK alone, DHS + HPHK, DHS + PO, and a case with DHS + HPHK + PO. One bias was that HPHK was not necessarily searched for at the adequate temperature in any particular kindred. Another bias was that PO, having been slim and transient, could recede prior to birth in some cases. Taken together, the clinical genetics led us to postulate that the multiple presentation of DHS might nonetheless stem from mutations all gathered in the gene encoding, presumably, an ion transporter or channel. Based on the study of a large Irish family with isolated DHS, preliminary results indicated that the responsible locus maps to chromosome 16 (16q23-qter).
Acellular (true) slime moulds (Myxomycetes) are capable of a transition to the stage of sclerotium — a dormant form of plasmodium produced under unfavourable environmental conditions. In this study, sclerotia of Fuligo septica were analyzed by means of electron paramagnetic resonance (EPR) spectroscopy. The moulds were cultivated in vitro on filter paper, fed with oat flour, and kept until the plasmodia began to produce sclerotia. The obtained sclerotia differed in colour from yellow through orange to dark-brown. The EPR spectra revealed a free radical, melanin-like signal correlated with the depth of the colour; it was strongest in the dark sclerotia. Sclerotization only took place when the plasmodia were starved and very slowly dried. Only the yellow sclerotia were able to regenerate into viable plasmodia. This suggests that myxomycete cytoplasm dehydration is an active process regulated metabolically. Plasmodial sclerotization may therefore serve as a convenient model system to study the regulation of cytoplasmatic water balance, and sclerotia as a convenient material for EPR measurements, combining the quality of plasmodia with the technical simplicity of the measurements characteristic of dry spores. Darkening of the sclerotia is most probably a pathological phenomenon connected with the impairment of water balance during sclerotization.
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