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91.
92.
The behavior of Pb in the A and B horizons of an Alfisol from Michigan and an Ultisol from Virginia was studied to determine the effects of “shock”; loading. Combined sequential extraction‐sorption isotherm analysis (CSSA), a relatively new and little tested method, was used in the study. After spiking to simulate severe contamination (~3000 to 60,000 mg/kg), CSSA revealed unexpectedly high levels of exchangeable Pb in the A horizon of the Alfisol and in both horizons of the Ultisol, and showed that the sorption capacities of the phases commonly responsible for fixation of Pb at low to moderate levels of contamination were exceeded. Carbonate sorbed the bulk of the Pb in the Alfisol B horizon and has a high sorption capacity in both soils, despite the presence of other phases with a strong affinity for Pb. Thus, when shock loading occurs (e.g., at a shooting range or dump sites), the highly contaminated A horizons of both soils are expected to pose a serious toxic hazard to humans, and groundwater contamination is possible in association with the Ultisol. CSSA proved useful for determining the sorption capacities of the individual phases while together in a natural soil system and therefore is a valuable method for predicting the attenuation capabilities of soils. 相似文献
93.
Bruce A. Davis Istvan Edes Ramesh C. Gupta Ellen F. Young Hae Won Kim Nancy A. E. Steenaart Grazyna Szymanska Evangelia G. Kranias 《Molecular and cellular biochemistry》1990,99(2):83-88
The calcium transport mechanism of cardiac sarcoplasmic reticulum (SR) is regulated by a phosphoregulatory mechanism involving the phosphorylation-dephosphorylation of an integral membrane component, termed phospholamban. Phospholamban, a 27,000 Da proteolipid, contains phosphorylation sites for three independent protein kinases: 1) cAMP-dependent, 2) Ca2+-calmodulin-dependent, and 3) Ca2+-phospholipid-dependent. Phosphorylation of phospholamban by any one of these kinases is associated with stimulation of the calcium transport rates in isolated SR vesicles. Dephosphorylation of phosphorylated phospholamban results in the reversal of the stimulatory effects produced by the protein kinases. Studies conducted on perfused hearts have shown that during exposure to beta-adrenergic agents, a good correlation exists between the in situ phosphorylation of phospholamban and the relaxation of the left ventricle. Phosphorylation of phospholamban in situ is also associated with stimulation of calcium transport rates by cardiac SR, similar to in vitro findings. Removal of beta-adrenergic agents results in the reversal of the inotropic response and this is associated with dephosphorylation of phospholamban. These findings indicate that a phospho-regulatory mechanism involving phospholamban may provide at least one of the controls for regulation of the contractile properties of the myocardium. 相似文献
94.
Abstract HPA proteolytic assay was used to study the dependence of proteolysis on phosphorus in fresh water. Inorganic phosphate (Pi ) stimulated the growth of bacteria producing proteases in water when P was limiting factor, but did not affect the biochemical activity of enzymes which were P-in-dependent. In proteolytic assays, bacteria utilised nitrogen and carbon from HPA. Therefore, during long incubations, significant increases in microbial biomass were observed. The original HPA procedure [12] gives artificial and non-realistic values of proteolytic rates in aquatic habitats due to accelerated and uncontrolled bacterial growth and enzyme production during the assay. The use of toluene to prevent microbial growth in HPA assays is recommended [10]. 相似文献
95.
Accumulation of phenolics in barley seedlings was examined in relation to elongation; the seedlings were cultivated at 5 °C
or 26 °C in light or in darkness. It was found that a higher accumulation of phenolics (mainly saponarin) was accompanied
by slower elongation. This relation was repeatedly observed regardless of whether growth retardation or stimulation was obtained
by light and temperature conditions of growth or treatment with CCO orp-fluorophenylalanine (p-FPA), respectively. It is proposed that PAL and peroxidase activities are responsible for maintaining the level of phenolics
in seedlings. These enzyme activities are differently influenced by temperature conditions of growth. It is also suggested
that accumulation of saponarin may lead to slowing down the growth by stimulating IAA oxidase and lowering the auxin level
in the tissues. Thus, phenolics may belong to the factors through which environmental conditions influence elongation of seedlings. 相似文献
96.
Furmanowa Miroslawa Glowniak Kazimierz Syklowska-Baranek Katarzyna Zgórka Grazyna Józefczyk Aleksandra 《Plant Cell, Tissue and Organ Culture》1997,49(1):75-79
We have analysed the effect of some culture conditions and media components on callus growth rate and production of taxanes
in callus of Taxus × media var. Hatfieldii. For callus induction and maintenance a Gamborg B5 medium and a White - Rangaswamy
medium (WR) with different modifications were used. On an improved WR medium (containing 10 μM picloram) the callus growth
factor increased up to 5.8 fold (fresh weight). Picloram only enhanced the growth of callus, but not taxane production. On
WR medium with (100 μM) methyl jasmonate the paclitaxel content increased from 2.37 μg g-1 to 90 μg g-1 and cephalomannine
from 5.14 μg g-1 to 29.14 μg g-1 (dry weight), whereas growth of the cultures ceased. The presence of paclitaxel and cephalomannine
was established by high performance liquid chromatography.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
97.
Synakiewicz Anna Stanislawska-Sachadyn Anna Sawicka-Zukowska Malgorzata Galezowska Grazyna Ratajczyk Joanna Owczarzak Anna Skuza Malgorzata Wolska Lidia Stachowicz-Stencel Teresa 《Amino acids》2021,53(1):133-138
Amino acids (AAs) play a crucial role in cancer cell metabolism. Levels of 22 plasma AAs at the time of diagnosis and after treatment were established among 39 pediatric cancer patients and 33 healthy children. Glutamic acid levels decreased and tryptophan levels increased during treatment. Cancer patients presented significantly lower levels of glutamine and leucine post-treatment while levels of 12 other AAs were higher comparing to controls. Results suggest that plasma free AA profile may serve as a prognostic biomarker.
相似文献98.
Dariusz Mitoraj Agnieszka Jańczyk Magdalena Strus Horst Kisch Grazyna Stochel Piotr B Heczko Wojciech Macyk 《Photochemical & photobiological sciences》2007,6(6):642-648
Visible light induced photocatalytic inactivation of bacteria (Escherichia coli, Staphylococcus aureus, Enterococcus faecalis) and fungi (Candida albicans, Aspergillus niger) was tested. Carbon-doped titanium dioxide and TiO2 modified with platinum(IV) chloride complexes were used as suspension or immobilised at the surface of plastic plates. A biocidal effect was observed under visible light irradiation in the case of E. coli in the presence of both photocatalysts. The platinum(IV) modified titania exhibited a higher inactivation effect, also in the absence of light. The mechanism of visible light induced photoinactivation is briefly discussed. The observed detrimental effect of photocatalysts on various microorganism groups decreases in the order: E. coli > S. aureus approximately E. faecalis>C. albicans approximately A. niger. This sequence results most probably from differences in cell wall or cell membrane structures in these microorganisms and is not related to the ability of catalase production. 相似文献
99.
We investigated the effect of the cyclic AMP-protein kinase A (PKA) signalling pathway on renal Na(+),K(+)-ATPase and ouabain-sensitive H(+),K(+)-ATPase. Male Wistar rats were anaesthetized and catheter was inserted through the femoral artery into the abdominal aorta proximally to the renal arteries for infusion of the investigated substances. Na(+),K(+)-ATPase activity was measured in the presence of Sch 28080 to block ouabain-sensitive H(+),K(+)-ATPase and improve specificity of the assay. Dibutyryl-cyclic AMP (db-cAMP) administered at a dose of 10(-7) mol/kg per min and 10(-6) mol/kg per min increased Na(+),K(+)-ATPase activity in the renal cortex by 34% and 42%, respectively, and decreased it in the renal medulla by 30% and 44%, respectively. db-cAMP infused at 10(-6) mol/kg per min increased the activity of cortical ouabain-sensitive H(+),K(+)-ATPase by 33%, and medullary ouabain-sensitive H(+),K(+)-ATPase by 30%. All the effects of db-cAMP were abolished by a specific inhibitor of protein kinase A, KT 5720. The stimulatory effect on ouabain-sensitive H(+),K(+)-ATPase and on cortical Na(+),K(+)-ATPase was also abolished by brefeldin A which inhibits the insertion of proteins into the plasma membranes, whereas the inhibitory effect on medullary Na(+),K(+)-ATPase was partially attenuated by 17-octadecynoic acid, an inhibitor of cytochrome p450-dependent arachidonate metabolism. We conclude that the cAMP-PKA pathway stimulates Na(+),K(+)-ATPase in the renal cortex as well as ouabain-sensitive H(+),K(+)-ATPase in the cortex and medulla by a mechanism requiring insertion of proteins into the plasma membrane. In contrast, medullary Na(+),K(+)-ATPase is inhibited by cAMP through a mechanism involving cytochrome p450-dependent arachidonate metabolites. 相似文献
100.
Piotr Czekaj Andrzej Plewka Marcin Kamiriski Grazyna Nowaczyk‐Dura Krzysztof Pawlicki Ewa Wielgus‐Serafińska 《Biological Rhythm Research》2013,44(1):67-75
Abstract An age‐associated alterations in daily and circadian changes of cytochrome P‐450‐linked monooxygenases system activity were studied using 1‐, 6‐ and 12‐months old male Wistar rats, in winter and in spring season. Cytochrome P‐450 and NADPH‐cytochrome P‐450 reductase showed 12h rhythm in all investigated age groups of animals. Cytochrome b5 and NADH‐cytochrome b5 reductase were characterized by a 12h daily rhythm in 1‐month old rats, but in older ones 24h circadian rhythm was found. There was not significant changes of the rhythm pattern in the activity of investigated MFO system ingredients in rats of different age, between spring and winter. 相似文献