Search results for "otas"
showing 10 items of 1136 documents
Kinetic modeling of ion conduction in KcsA potassium channel.
2005
KcsA constitutes a potassium channel of known structure that shows both high conduction rates and selectivity among monovalent cations. A kinetic model for ion conduction through this channel that assumes rapid ion transport within the filter has recently been presented by Nelson. In a recent, brief communication, we used the model to provide preliminary explanations to the experimental current-voltage J-V and conductance-concentration g-S curves obtained for a series of monovalent ions (K(+),Tl(+), and Rb(+)). We did not assume rapid ion transport in the calculations, since ion transport within the selectivity filter could be rate limiting for ions other than native K(+). This previous wor…
Organotin(IV) complexes ofN-[(2Z)-3-hydroxy-1-methyl-2-butenylidene]glycine
2003
Organotin(IV) derivatives of N-[(2Z)-3-hydroxy-1-methyl-2-butenylidene]glycine have been synthesized and characterized by 1H, 13C, 119Sn NMR, 119Sn Mossbauer, and IR spectroscopy along with elemental analyses. The di- and triorganotin(IV) complexes were readily obtained from the reactions of organotin halides and sodium/potassium N-[(2Z)-3-hydroxy-1-methyl-2-butenylidene]glycinate. The diorganotin compound reacted with Ph3SnCl in refluxing benzene to give the mixed organotin dinuclear complex of composition Ph2Sn(2-OC(CH3)-C(H)C(CH3)NCH2COO)·Ph3SnCl, which was characterized by single crystal X-ray structure determination. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:149–154, 2003; Publ…
Interspecific hybridization improves the performance of Lotus spp. under saline stress
2019
Abstract Salinity is one of the most frequent limiting conditions in pasture production for grazing livestock. Legumes, such as Lotus spp. with high forage quality and capable of adapting to different environments, improves pasture performance in restrictive areas. In order to determine potential cultivars with better forage traits, the current study assess the response to salt stress of L. tenuis, L. corniculatus and a novel L. tenuis x L. corniculatus accession. For this purpose, chlorophyll fluorescence, biomass production, ion accumulation and anthocyanins and proanthocyanidins levels have been evaluated in control and salt-treated plants PSII activity was affected by salt in L. tenuis,…
Light-Dependent Translocation of Arrestin in Rod Photoreceptors is Signaled through a Phospholipase C Cascade and Requires ATP
2009
Light adaptation of rod photoreceptors induces translocation of arrestin from inner segments (IS) to outer segments (OS). Our study suggests that components of the G-protein linked phosphoinositide pathway play a role in signaling the initiating events of arrestin translocation. We show that arrestin translocation can be stimulated by activators of phospholipase C (PLC) and protein kinase C (PKC) in the absence of light. Conversely, arrestin translocation to the OS is significantly slowed by inhibitors of PLC and PKC.In the second part of this study, we investigated the mechanism by which arrestin translocates in response to light. Other investigators have suggested that arrestin translocat…
TFIIH Operates through an Expanded Proximal Promoter To Fine-Tune c-myc Expression
2004
A continuous stream of activating and repressing signals is processed by the transcription complex paused at the promoter of the c-myc proto-oncogene. The general transcription factor IIH (TFIIH) is held at promoters prior to promoter escape and so is well situated to channel the input of activators and repressors to modulate c-myc expression. We have compared cells expressing only a mutated p89 (xeroderma pigmentosum complementation group B [XPB]), the largest TFIIH subunit, with the same cells functionally complemented with the wild-type protein (XPB/wt-p89). Here, we show structural, compositional, and functional differences in transcription complexes between XPB and XPB/wt-89 cells at t…
Simulation Analysis of the Influence of Hemodialysis Control Parameters on Exchange Processes during Therapy
1992
The effect of dialysis control parameters (dialysate composition, ultrafiltration rate, blood flow rate) on the patient's internal milieu were studied using a mathematical model for the description of the dynamic exchange processes during hemodialysis. This model simulates the electrolyte and water distribution, the acid-base and the oxygenation state as well as the ventilation. The dialysate sodium concentration affects mainly the intra-/ extracellular water and the potassium distribution. The dialysate bicarbonate and acetate concentrations control the acid-base state and the electrolyte distribution (sodium and potassium). In addition, the dialysate acetate concentration has a strong ef…
Inhibition of the system luminol-H2O2-Fe(CN)63− chemiluminescence by the Mn(II) indirect determination of isoniazid in a pharmaceutical formulation
1998
A flow injection procedure for the indirect chemiluminescent determination of isoniazid is proposed. The method is performed in a flow-injection manifold provided with a solid-phase reactor. The reactor was made from manganese dioxide physically entrapped by polymerization; the redox reaction isoniazid-manganese dioxide released Mn(II) which was monitored through its inhibitory effect on the reaction between luminol and hydrogen peroxide in presence of potassium hexacyanoferrate (III). The procedure resulted in a linear calibration graph over the range 5-15 mg/L of isoniazid with a sample throughput of 43 samples/h. The influence of foreign compounds was studied and the method was applied t…
FIA-Chemiluminescence Determination of Acridine Yellow
2003
Abstract The direct determination of yellow acridine is performed by a FIA assembly on the basis of the oxidation of the acridine. The acridine solution is injected into a pure water stream. This solution merges with the oxidant solution (KMnO4 in sulfuric acid medium) and the resulting chemiluminescence allows the method to be applied over the range 0.01–100 mg L−1 of acridine with a correlation coefficient of 0.9997. The relative standard deviation (%) is 1.6 and the sample throughput 60 h−1. The influence of foreign substances is also tested. The new method is applied to the determination of yellow acridine in waste waters.
Einflu� eines diphenolischen Laxans (Bisacodyl) auf den Wasser- und Elektrolyttransport im menschlichen Colon
1974
Bei 5 Versuchspersonen wurde die Wirkung von Bisacodyl auf die Wasser- und Elektrolytbewegungen im menschlichen Colon untersucht. Das Colon wurde durch eine Sonde perfundiert, die in das Coecum plaziert wurde. Die Perfusionslosung enthielt NaCl (140 maq/l) als Chlorid und Bicarbonat und K (2,8 maq/l) als Chlorid sowie14C-Polyathylenglykol als Marker. Sie wurde mit einer Rate von 10 ml/min perfundiert und uber ein Darmrohr im Rectum wieder aufgefangen.
Study on the histamine-like activity of guanfacine
1990
Abstract The effects of guanfacine have been studied on guinea-pig isolated atria and diethylstilboestrol-treated rat isolated uterus to determine whether it possesses histamine-like activity. Guanfacine produced a concentration-dependent negative chronotropic effect which was not modified by ranitidine (0.1 μM). In rat isolated uterus contracted by KCl, clonidine (5–5000 μM) produced concentration-dependent relaxation which was blocked by ranitidine (0.1 μM), but guanfacine only produced relaxation at high concentrations (100–1000 μM), and this was not affected by ranitidine (0.1 μM). It is concluded that guanfacine, unlike clonidine, does not produce effects due to activation of H2-recept…