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M. Gabriella Gabrielli 《Journal of enzyme inhibition and medicinal chemistry》2013,28(3):283-286
The villus cavity cells, a specific cell type of the chick chorioallantoic membrane, express both cytosolic carbonic anhydrase in their cytoplasm and [Formula: See Text] anion exchangers at their basolateral membranes. By immunohistochemical analysis, we show here that villus cavity cells specifically react with antibodies directed against the membrane-associated form of carbonic anhydrase, CAIV. Staining is restricted to the apical cell membranes, characteristically invaginated toward the shell membrane, as well as to endothelia of blood vessels present in the mesodermal layer. The occurrence of a membrane-associated CA form at the apical pole of villus cavity cells, when definitively confirmed, would be fairly consistent with the role proposed for these cells in bicarbonate reabsorption from the eggshell so to prevent metabolic acidosis in the embryo during development. 相似文献
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Satratoxins H and G, verrucarin J, and roridin E were isolated from the bedding straw of 200 sport horses exhibiting typical symptoms of stachybotryo-toxicosis. At the same time, the oat feed consumed by the horses contained non-macrocyclicFusarium trichothecenes: T-2 toxin and diacetoxyscirpenol. 相似文献
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C Fabris D Basso L Benini T Meggiato G Del Favero G Cavallini M P Panozzo P Fogar C Angonese I Vantini 《Enzyme》1989,42(2):80-86
Serum and urine elastase 1, its renal output and clearance and urinary gamma-glutamyltransferase and ribonuclease excretions were measured in 16 patients with pancreatic cancer, 23 with chronic pancreatitis and in 22 healthy controls in order to evaluate elastase 1 plasma-urine transfer in chronic pancreatic disease and to investigate any factors that might influence the clearance of this enzyme. In an additional group of 17 patients with different pancreatic diseases the serum molecular size distribution of elastase 1 after chromatography was ascertained. An increased urinary elastase 1 output was found in 4/16 patients with pancreatic cancer and in 6/23 with chronic pancreatitis. No correlation was found between circulating elastase 1 and its urinary output; a negative correlation was detected between the serum levels of this enzyme and its clearance. The excretion of ribonuclease and gamma-glutamyltransferase was correlated with elastase 1 output and clearance. While the majority of elastase 1 in serum was accounted for by high molecular forms, probably the expression of complexes with serum inhibitors, free circulating enzyme was present in all patients with high serum elastase 1. Our findings suggest that elastase 1 urinary excretion increases in some patients with chronic pancreatic disease regardless of the neoplastic or inflammatory nature of the illness. Although the availability of different amounts of ultrafiltrable enzyme may play a role in influencing elastase 1 plasma-urine transfer, renal tubular damage appears to be the most important factor influencing the increase in the urinary output of elastase 1. 相似文献
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M A Francesconi A Donella-Deana V Furlanetto L Cavallini P Palatini R Deana 《Biochimica et biophysica acta》1989,999(2):163-170
Succinyl-CoA:3-hydroxy-3-methylglutarate coenzyme A transferase, previously identified in rat-liver mitochondria (Deana et al. (1981), Biochim. Biophys. Acta 662, 119-124), was purified to near homogeneity and further characterized. After the last purification steps consisting of Ultrogel AcA-44 filtration and agarose-hexane-coenzyme A chromatography, the enzyme was apparently tetrameric with a mass of 48-52 kDa determined by gel filtration on Sephadex G-75, ultracentrifugation through a sucrose gradient and SDS-gel electrophoresis. By means of a HPLC technique developed for measuring the CoA esters we could determine the enzyme activity in both forward and reverse directions and show that the kinetic constants, i.e., Km of reactants and Vmax, are not too different for the two reactions. Double-reciprocal plots of the enzyme velocities versus the concentration of one substrate at different fixed concentrations of the other substrate gave families of straight lines converging below the substrate-abscissa for both forward and backward reactions, indicating a kinetic mechanism of rapid equilibrium random Bi-Bi type. The competitive inhibition of the product succinate with respect to both reactants, 3-hydroxy-3-methylglutarate and succinyl-CoA, as well as the Haldane relationships are consistent with this conclusion. An inhibitory effect on CoA transferase activity by acetate, acetoacetate, acetyl-CoA, acetoacetyl-CoA, coenzyme A, carnitine, ZnCl2 and high concentrations of the monovalent anions ClO4-, F-, I- and Cl- was also found. 相似文献
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Addition of 1 mM Ca/EGTA complex (1:1 ratio) to an incubation medium containing 1.5 mM Ca2+ produced a notable increase in the Ca2+ cycling in ejaculated bovine spermatozoa. Similar results were also obtained with the Ca/EDTA and Ca/EDTA complexes or with the heavy metal chelator DTPA (50 microM). Ba2+, Ni2+ or Co2+ added at 0.1 mM concentration abolished the stimulatory effect of the Ca/EGTA complex on Ca2+ cycling, whereas it did not affect the calcium movement in the absence of the calcium chelator complex. It is concluded that small amounts of these cations should be bound to the plasma membrane of bovine spermatozoa and inhibit the cellular calcium influx. 0.1 mM Cd2+ and NEM or 1 mM diamide produced a calcium efflux from the spermatozoa together with an inhibition of cellular motility and an increase in glutamate-oxaloacetate transaminase release. Conversely the impermeant sulfhydryl reagent mersalyl caused a net calcium efflux but did not alter the cellular motility nor the transaminase release. It is suggested that the permeant thiol reagents could decrease the spermatozoal mobility by impairing the mitochondrial ATP-synthesis. 相似文献
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TFIID is required for in vitro transcription of the human U6 gene by RNA polymerase III 总被引:26,自引:6,他引:20
K A Simmen J Bernus H D Parry H G Stunnenberg A Berkenstam B Cavallini J M Egly I W Mattaj 《The EMBO journal》1991,10(7):1853-1862