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 10,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cerebral effects of alterations in plasma osmolality (Osm) and colloid oncotic pressure (COP) were examined in normocarbic, normothermic, pentobarbital-anesthetized rabbits that had been subjected to cryogenic brain injury. Monitored variables in all animals included mean arterial, right atrial, and intracranial pressures (MAP, CVP, and ICP), electroencephalographic (EEG) recordings, and cerebral blood flow (CBF). When surgical preparation was complete, a left parietal lesion was produced with liquid nitrogen. Group 1 (control, n = 8) animals subsequently received only maintenance fluids [lactated Ringer's solution (LR)]. One hour after injury, 3 other groups of animals underwent 45 minutes of plasmapheresis, carried out by arterial phlebotomy (packed red cells returned), with separated plasma being replaced by one of three fluids given in amounts sufficient to maintain MAP and CVP at baseline values. The three fluids were 1) 6% hetastarch in hypo-osmotic LR [Group 2 (Hypo-Osm), n = 6; COP = 21 mm Hg, Osm = 130 mOsm/kg]; 2) iso-osmotic LR [Group 3 (Hypo-COP), n = 8; COP = 0; Osm = 305]; and 3) 6% hetastarch in iso-osmotic LR [Group 4 (Iso-Osm/COP), n = 8; COP = 21, Osm = 310]. The animals were killed by exsanguination 25 minutes after completion of plasmapheresis. The brain was removed, the hemispheres separated, weighed, and sliced, and the specific gravities (SpGr) of the regional tissue determined. There were no differences in MAP, CVP, regional CBF, or EEG activity among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Acute effects of changing plasma osmolality and colloid oncotic pressure on the formation of brain edema after cryogenic injury. 271 75

The effects of an 8-h period of reduced colloid oncotic pressure (COP) on cerebral edema formation following cryogenic brain injury were studied in 24 normothermic, normocarbic rabbits. Anesthesia was induced with halothane and catheters inserted to permit the monitoring of arterial, right atrial, and intracranial pressures (MAP, CVP, and ICP, respectively). When surgery was complete, halothane was discontinued, 40 mg/kg of pentobarbital was given iv, and ventilation continued with 66% N2O/balance O2. A left parietal cryogenic injury was then produced using liquid N2, and the animals assigned to one of three groups. In group 1 (Control, n = 8), only maintenance lactated Ringer's solution (LR) was given for the remainder of the study. Beginning 30 min after injury, animals in the other two groups (n = 8 each) underwent 45 min of plasmapheresis (arterial phlebotomy, with packed cells returned). In group 2 (Iso-COP) separated plasma was replaced with 6% hetastarch in LR, while in group 3 (Hypo-COP), plasma was replaced with LR alone. In both groups, the volume of fluid given was adjusted to maintain MAP and CVP at baseline values. After plasmapheresis, animals subsequently received only maintenance LR. Eight and one-half hours after the injury (8 h after the start of plasmapheresis), animals were killed and the brains removed. Regional tissue specific gravities (SpGr) and water contents (%H2O) were measured respectively by microgravimetry and drying. In addition, the %H2O of samples of skeletal muscle and small bowel were determined to assess peripheral edema formation. There were no important intergroup differences in MAP, CVP, ICP, blood gases, or osmolality at any time.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prolonged reduction in colloid oncotic pressure does not increase brain edema following cryogenic injury in rabbits. 280 12

A pre-oxidation procedure which converts arsenite [As(III)] into arsenate [As(v)] was investigated in urinary arsenic speciation prior to on-line photo-oxidation hydride generation with ICP-MS detection. This sample pre-oxidation method eliminates As(III) and As(v) preservation concerns and simplifies the chromatographic separation. Four oxidants, Cl2, MnO2, H2O2 and I3-, were investigated. Chlorine (ClO-aq) and MnO2 selectively converted As(III) into As(v) in pure water samples, but the conversion was inefficient in the complex urine matrix. Oxidation of As(III) by H2O2 was least affected by the urine matrix, but the removal of excess H2O2 at pH 10 proved difficult. The most appropriate oxidant for the selective conversion of As(III) into As(v) with minimal interference from the urine matrix is I3- at pH 7. Unlike H2O2, excess oxidant can be easily removed by the addition of S2O3(2-). The I3-(-)S2O3(2-) treatment on a fortified sample of reconstituted NIST SRM 2670 freeze dried urine indicated that arsenobetaine (AsB), dimethlyarsinic acid (DMA), monomethylarsonic acid (MMA) and As(v) were not chemically degraded with recoveries ranging from 95 to 102% for all arsenicals. Sample clean-up involved pH adjustment prior to C18 filtration in order to achieve efficient As(III) conversion and quantitative recoveries of AsB and DMA. The concentrations determined in NIST SRM 2670 freeze dried urine were AsB 17.2 +/- 0.5, DMA 56 +/- 4 and MMA 10.3 +/- 0.3 with a combined total of 83 +/- 5 micrograms L-1 (+/- 2 sigma).
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PMID:Application of sample pre-oxidation of arsenite in human urine prior to speciation via on-line photo-oxidation with membrane hydride generation and ICP-MS detection. 1093 62

The deferrization mechanism of apoferritin was established, and the spectra variation of apoferritin was compared with that of holoferritin. Sodium hyposulfite is a strong reducing agent, therefore, was applied to deoxidize holoferritin to release iron ion, and connection of iron of buffer was measured by the 2,2-dipyridyl. Apoferritin was detected by ICP-MS. Holoferritin was found to have no absorption compared with apoferritin by UV analysis, and have no fluorescence emission spectra in contrast with apoferritin by fluorescence analysis.
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PMID:[Study on of deferrization mechanism of apoferritin and the effect of spectra variation with holoferritin]. 2209 69

In response to oxidative stress the biosynthesis of the ROS scavenger, glutathione is induced. This requires the induction of the sulfate reduction pathway for an adequate supply of cysteine, the precursor for glutathione. Cysteine also acts as the sulfur donor for the sulfuration of the molybdenum cofactor, crucial for the last step of ABA biosynthesis. Sulfate and sulfite are, respectively, the precursor and intermediate for cysteine biosynthesis and there is evidence for stress-induced sulfate uptake and further downstream, enhanced sulfite generation by 5'-phosphosulfate (APS) reductase (APR, EC 1.8.99.2) activity. Sulfite reductase (SiR, E.C.1.8.7.1) protects the chloroplast against toxic levels of sulfite by reducing it to sulfide. In case of sulfite accumulation as a result of air pollution or stress-induced premature senescence, such as in extended darkness, sulfite can be oxidized to sulfate by sulfite oxidase. Additionally sulfite can be catalyzed to thiosulfate by sulfurtransferases or to UDP-sulfoquinovose by SQD1, being the first step toward sulfolipid biosynthesis.Determination of total sulfur in plants can be accomplished using many techniques such as ICP-AES, high-frequency induction furnace, high performance ion chromatography, sulfur combustion analysis, and colorimetric titration. Here we describe a total sulfur detection method in plants by elemental analyzer (EA). The used EA method is simple, sensitive, and accurate, and can be applied for the determination of total S content in plants.Sulfate anions in the soil are the main source of sulfur, required for normal growth and development, of plants. Plants take up sulfate ions from the soil, which are then reduced and incorporated into organic matter. Plant sulfate content can be determined by ion chromatography with carbonate eluents.Sulfite is an intermediate in the reductive assimilation of sulfate to the essential amino acids cysteine and methionine, and is cytotoxic above a certain threshold if not rapidly metabolized and can wreak havoc at the cellular and whole plant levels. Plant sulfite content affects carbon and nitrogen homeostasis Therefore, methods capable of determining sulfite levels in plants are of major importance. Here we present two robust laboratory protocols which can be used for sulfite detection in plants.Thiosulfate is an essential sulfur intermediate less toxic than sulfite which is accumulating in plants in response to sulfite accumulation. The complexity of thiosulfate detection is linked to its chemical properties. Here we present a rapid, sensitive, and accurate colorimetric method based on the enzymatic conversion of thiosulfate to thiocyanate.The plant sulfolipid sulfoquinovosyldiacylglycerol (SQDG) accounts for a large fraction of organic sulfur in the biosphere. Aside from sulfur amino acids, SQDG represents a considerable sink for sulfate in plants and is the only sulfur-containing anionic glycerolipid that is found in the photosynthetic membranes of plastids. We present the separation of sulfolipids from other fatty acids in two simple ways: by one- and two-dimensional thin-layer chromatography.
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PMID:Determination of Total Sulfur, Sulfate, Sulfite, Thiosulfate, and Sulfolipids in Plants. 2873 2