30,982 research outputs found
ELECTRONIC AND GEOMETRIC STRUCTURE OF AND
No full textAuthor Institution: Department of Chemistry, Michigan State UniversityThe electronic and geometric structures of and have been studied using ab-inito MCSCF and Cl tychniques. The calculated bond lenth, and for the first three states of are [FIGURE] We calsulate the bond length in to be 1.75\AA with an angle of . While is strongly bond relative to , preliminary results suggest the reaction is isoergic. In addition to comparing these results to experiment we will present an analysis of the bonding
[<sup>3</sup>H]-SCH 23390 binding and cAMP accumulation after MPD withdrawal in SHR PFC.
No full text<p>(A) [<sup>3</sup>H]-SCH 23390 binding in the 24-h (PN56) and 10-day (PN65) MPD withdrawal and control groups (n = 4). (B) Basal cAMP accumulation in the 24-h (PN56) and 10-day (PN65) withdrawal group and after SCH 23390 exposure (50 μM; n = 4–7). Results are expressed as means ± S.E.M. ** = p < 0.01; *** = p < 0.001, vs. Control. a = p < 0.001, vs. SCH. b = p < 0.001, vs. MPD.</p
H(+)-ATPases of renal cortical and medullary endosomes are differentially sensitive to Sch-28080 and omeprazole
No full text Adenosinetriphosphatase (ATPase) activity stimulated by K+ and inhibited by Sch-28080 (SCH), omeprazole (OME), and vanadate has been measured in microsomes from mammalian renal medulla and attributed to a kidney isoform of the H(+)-K(+)-ATPase. To determine whether the H(+)-K(+)-ATPase inhibitors could also inhibit the vacuolar (V)-type H(+)-adenosinetriphosphatase (H(+)-ATPase, i.e., H+ pump) in mammalian intracellular vesicles, we examined their effects on bafilomycin-sensitive acidification in renal cortical vesicles (CEV) and medullary endocytic vesicles (MEV). Rats were injected with fluorescein isothiocyanate-labeled dextran, and labeled endosomes were enriched from kidney tissue homogenates by differential and Percoll density gradient centrifugation. In the CEV, the V-type H+ pump was inhibited 25% by SCH and 30% by OME (100 microM each). Whereas the inhibition by OME was concentration and time dependent, the inhibition by SCH was only concentration dependent. Inhibition by these compounds was similar in the presence of 50 mM K+ (in = out) and in the complete absence of K+, thus ruling out a significant involvement of H(+)-K(+)-ATPase-mediated acidification. Inhibition, however, was not observed with 10 microM SCH and OME. The sensitivity of the V-type H+ pump to 100 microM SCH and OME in CEV was confirmed by the comparable inhibitions of intravesicular acidification observed in acridine orange fluorescence quench studies and by inhibition of Pi liberation in an ATPase assay. We also found that the V-type H+ pump in isolated rat liver endosomes is sensitive to 100 microM SCH and OME to a similar degree. In the MEV, acidification was only weakly affected by 100 microM SCH and OME, thus suggesting that H(+)-ATPases in endosomes from cortical and medullary tubules are different, possibly due to a previously described selective expression of subunit isoforms. Our finding indicates the importance of using low concentrations (< 10 microM) of OME and SCH in studies of H(+)-K(+)-ATPase in nongastric tissues to avoid misinterpretation of the data due to nonspecific inhibition of V-type H(+)-ATPases. </jats:p
Effect of 6-h incubation with Sch A and Sch B in lipopolysaccharide (LPS)-activated pro-inflammatory cytokines in RAW264.7 macrophages.
No full textEffect of 6-h incubation with Sch A and Sch B in lipopolysaccharide (LPS)-activated pro-inflammatory cytokines in RAW264.7 macrophages.</p
Effect of Sch B incubation on lipopolysaccharide (LPS)-activated pro-inflammatory cytokines at 16 h- post Sch exposure in RAW264.7 macrophages.
No full textEffect of Sch B incubation on lipopolysaccharide (LPS)-activated pro-inflammatory cytokines at 16 h- post Sch exposure in RAW264.7 macrophages.</p
Sch-28080 inhibits bafilomycin-sensitive H+ secretion in turtle bladder independently of luminal [K+]
No full text To explore the possible contribution of an H-K-adenosine-triphosphatase (H-K-ATPase) to H+ secretion (JH) in the isolated turtle bladder, we measured electrogenic JH (JeH) as short-circuit current and total JH (JTH) by pH stat titration in the presence of ouabain at different ambient K+ concentration ([K+]) and during luminal addition of a known gastric H-K-ATPase inhibitor, Schering (Sch)-28080. JH was not reduced by decreasing ambient [K+] to undetectable or very low levels (< 0.05 mM by atomic absorption) and luminal BaCl2 addition to further reduce local [K+] at the apical membrane. These K(+)-removal studies indicate that H+ transport is not coupled to countertransport of K+. JTH did not exceed JeH at any point: in K(+)-free solutions JTH was 0.73 +/- 0.05, and JeH was 0.95 +/- 0.08 mumol/h; in standard (3.5 mM) K+ solutions JTH was 0.72 +/- 0.05 and JeH 0.98 +/- 0.06 mumol/h; in high (118 mM) K+ solutions JTH was 0.65 +/- 0.07 and JeH 0.94 +/- 0.08 mumol/h. Sch-28080 caused a rapid inhibition of JH, with similar half-maximal inhibitory concentrations (IC50) in K(+)-free, standard [K+], and high [K+] solutions. Bafilomycin inhibited JeH and JTH with an IC50 of approximately 100 nM. The observed non-potassium-competitive inhibition of JH by Sch-28080 and the bafilomycin sensitivity distinguish the H-ATPase of the turtle bladder from the gastric H-K-ATPase. The rapidity of the inhibition by Sch-28080 suggests that it acts at an accessible luminal site of the ATPase. </jats:p
Sch-28080 depletes intracellular ATP selectively in mIMCD-3 cells
No full textTwo H+-K+-ATPase isoforms are present in kidney: the gastric, highly sensitive to Sch-28080, and the colonic, partially sensitive to ouabain. Upregulation of Sch-28080-sensitive H+-K+-ATPase, or “gastric” H+-K+-ATPase, has been demonstrated in hypokalemic rat inner medullary collecting duct cells (IMCDs). Nevertheless, only colonic H+-K+-ATPase mRNA and protein abundance increase in this condition. This study was designed to determine whether Sch-28080 inhibits transporters other than the gastric H+-K+-ATPase. In the presence of bumetanide, Sch-28080 (200 μM) and ouabain (2 mM) inhibited86Rb+uptake (>90%). That86Rb+uptake was almost completely abolished by Sch-28080 indicates an effect of this agent on the Na+-K+-ATPase. ATPase assays in membranes, or lysed cells, demonstrated sensitivity to ouabain but not Sch-28080. Thus the inhibitory effect of Sch-28080 was dependent on cell integrity.86Rb+-uptake studies without bumetanide demonstrated that ouabain inhibited activity by only 50%. Addition of Sch-28080 (200 μM) blocked all residual activity. Intracellular ATP declined after Sch-28080 (200 μM) but recovered after removal of this agent. In conclusion, high concentrations of Sch-28080 inhibit K+-ATPase activity in mouse IMCD-3 (mIMCD-3) cells as a result of ATP depletion.</jats:p
Palinotaxonomia de espécies de Chrysolaena H. Rob., Echinocoryne H. Rob. e Stenocephalum Sch. Bip. (Vernonieae-Compositae) ocorrentes no sudeste do Brasil Palynotaxonomy of Chrysolaena H. Rob., Echinocoryne H. Rob. and Stenocephalum Sch. Bip. (Vernonieae-Compositae) species from Southeast Brazil
No full textRealizou-se o estudo polínico de 11 espécies distribuídas em três gêneros, Chrysolaena H. Rob., Echinocoryne H. Rob. e Stenocephalum Sch. Bip., pertencentes à subtribo Vernoniinae, com o objetivo de contribuir para a caracterização polínica dessas espécies e avaliar sua posição taxonômica. Os grãos de pólen foram acetolisados, analisados e fotomicrografados sob microscopia de luz. Para observar detalhes da superfície e abertura, grãos de pólen não acetolisados foram analisados em microscópio eletrônico de varredura e de transmissão. Os gêneros foram separados, em uma chave palinológica, em dois grandes grupos utilizando-se o número total e a organização das lacunas que formam o padrão lofado. No primeiro grupo foram reunidas espécies de Echinocoryne H. Rob. que possuem grãos de pólen com 30 lacunas. No segundo grupo, espécies de Chrysolaena H. Rob. e Stenocephalum Sch. Bip., com 29 lacunas. As espécies de Echinocoryne são palinologicamente homogêneas, afastando-se apenas Echinocoryne holosericea (Mart. ex DC.) H. Rob. e Echinocoryne schwenkiaefolia (Mart. ex DC.) H. Rob. de Echinocoryne pungens (Gardn.) H. Rob. e Echinocoryne stricta (Gardn.) H. Rob. Estas duas últimas não puderam ser separadas pelas características polínicas. Considera-se, após o estudo aqui realizado, que as características polínicas isoladamente não são suficientes para definir os três gêneros aqui analisados.A pollen study of 11 species distributed in three genera, Chrysolaena H. Rob., Echinocoryne H. Rob. and Stenocephalum Sch. Bip. belonging to the Vernoniinae subtribe was carried out to characterize the pollen of these species and evaluate their taxonomic position. The pollen grains were acetolysed, analyzed and illustrated using light microscopy. For further details of pollen surface and aperture, non-acetolysed pollen grains were analysed by means of scanning and transmition electron microscopy. The genera were separated by a pollen key in two major groups using organization and number of lacunae that form the lophate pattern. In the first group, Echinocoryne H. Rob. species have pollen grains with 30 lacunae and in a second group, Chrysolaena H. Rob. and Stenocephalum Sch. Bip. species with 29 lacunae. Echinocoryne H. Rob. species are palynologically homogenous and only Echinocoryne holosericea (Mart. ex DC.) H. Rob. and Echinocoryne schwenkiaefolia (Mart. ex DC.) H. Rob. can be separated from Echinocoryne pungens (Gardn.) H. Rob. and Echinocoryne stricta (Gardn.) H. Rob. The last two could not be distinguished using pollen characters. Our datashow that pollen characters alone are not enough to define the three genera
Effect of Sch A and Sch B incubation on the antioxidant response in RAW264.7 macrophages.
No full textRAW264.7 macrophages were incubated with Sch A or Sch B for 6 h. (A) Nuclear factor erythroid 2-related factor 2 (Nrf2) is a master transcription factor for the antioxidant system. Levels of Nrf2 and β-actin in cytosolic fractions as well as Nrf2 and lamin B1 in nuclear fractions of macrophages were measured using Western blot analysis. Whereas the level of Nrf2cytosolic was normalized relative to the β-actincytosolic level, Nrf2nuclear content was normalized relative to the lamin-B1nuclear level. The ratio of normalized nuclear Nrf2 to normalized cytosolic Nrf2 was determined to estimate the extent of Nrf2 nuclear translocation (which is indicative of Nrf2 activation) in RAW264.7 macrophages (left panel). Data are expressed as % control by normalizing relative to the vehicle-incubated control group. (B) Following 2 h of-exposure to Sch A or Sch B, the mRNA level of thioredoxin (TRX) was measured, as described in Fig 6. (C) Following a 16 h-exposure to Sch A and Sch B, the level of TRX was measured using Western blot analysis. The amount of TRX was normalized relative to the β-actin level and expressed as % control (right; lower panel). Value given are means ± SEM, with n = 3. * Significantly different from the vehicle control.</p
Effects of long-term treatment with Sch A and Sch B in concanavalin A (Con A)-activated splenocytes isolated from Sch A/Sch B-treated mice.
No full textFemale ICR mice were administered Sch A or Sch B orally [alone (0.25 nmol/kg/d) or in combination (0.125 nmol/kg/d) × 5 d], as described in Materials and Methods. Splenocytes were isolated from the spleen of Sch A/Sch B-treated mice, as described in Materials and Methods. (A) The isolated splenocytes were lysed and the levels of GSH in the cell lysate were measured. (B) Isolated splenocytes were incubated with Con A (1, 2 and 4 μg/mL) for 72 h. The Con A-induced proliferation of splenocytes was measured by MTT assay. The area under the curve (AUC) plotting the absorbance at 570 nm against the concentration of Con A was calculated and expressed as stimulation index. Data are expressed % control by normalizing with the vehicle control group. * Significantly different from the control group.</p
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