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991.
VIP was labeled with sodium 125iodide, and 125I-VIP was purified by reverse-phase high performance liquid chromatography. Optimal separations of 125I-VIP and unlabeled VIP were obtained using two C18-Novapak columns in series and a gradient of acetonitrile in triethylamine phosphate for elution. The specific activity of the 125I-VIP was 1.99±0.21 Ci/μmole, approaching the maximum specific activity of monoiodinated VIP (2.26 Ci/μmole). Radioimmunoassay and radioreceptorassay for VIP were more sensitive (2.6-fold, and 2.5-fold, respectively) using 125I-VIP purified by HPLC compared to 125I-VIP obtained from an open-end cellulose column. These results demonstrate the advantage of preparing purified 125I-VIP by HPLC for the accurate assay of VIP and VIP-receptors in tissues and biological fluids. 相似文献
992.
Khalil Ahmed Said A. Goueli H.Guy Williams-Ashman 《Biochemical and biophysical research communications》1983,112(1):139-146
The chemically inert trivalent ion cobalt(III) hexaammine, Co3+(NH3)6, was found to exert polyamine-like effects in enhancing certain cyclic nucleotide-independent protein kinase reactions catalyzed by nuclear enzyme preparations from rat ventral prostate or liver. At 1 mM, Co3+(NH3)6 stimulated chromatin- and also non-histone-protein-associated kinase activities with partially dephosphorylated phosvitin as substrate by 38% and 72% respectively, whereas chromatin-associated kinase-catalyzed phosphorylation of lysine-rich histones was not affected under the same conditions. 32P incorporation (from γ-32P-ATP) into endogenous protein substrates of chromatin or non-histone protein fractions catalyzed by their erdogencus kinase activity was increased by 47% and 153%, respectively. These effects of Co3+(NH3)6 were similar to those produced by 1mM spermine. Autoradiographic analysis of endogenous 32P-labelled nonhistone proteins revealed similar enhancements of the phosphorylation of several of the same proteins, induced by 1mM spermine or 1 mM Co3+(NH3)6 or 2mM spermidine. The stimulatory actions of polyamines or Co3+(NH3)6 were not mimicked by raising the ionic strength by addition of comparable concentrations of NaCl. The effects of 1 mM spermine and of 1 mM Co3+(NH3)6 tested separately were not additive. Phosphorylation of lysine-rich histones by beef heart cyclic AMP-dependent protein kinase was not affected by polyamines or Co3+(NH3)6 Various findings hint that the enhancement of cyclic nucleotide-independent kinase-catalyzed phosphorylation of certain protein substrates by spermidine, spermine and Co3+(NH3)6 is primarily due to interaction of these cations with appropriate protein substrates affecting their conformational status. Further, these effects of polyamines may be a reflection of their cationic charge properties rather than being dependent on any particular conformations assumed by the polyamines. 相似文献
993.
994.
995.
A pentadecapeptide amide with the C-terminal sequence (14–28) of the vasoactive intestinal peptide (VIP), but with the methionine residue in position 17 replaced by l-norleucine, was synthesized. The synthesis was carried out through stepwise chain lengthening, by the in situ technique. The norleucine-containing pentadecapeptide, l-arginyl-l-lysyl-l-glutaminyl-l-norleucyl-l-alanyl-l-valyl-l-lysyl-l-lysyl-l-tyrosyl- l-leucyl-l-asparaginyl-l-seryl-l-isoleucyl-l-leucyl-l-asparaginamide, was as active in relaxing different smooth-muscle preparations as the methionine-containing parent sequence. 相似文献
996.
The digestibility of treated maize cobs was studied using Romney Marsh wether sheep in a 2 × 3 factorial design; maize cobs were ground through a 10- or 6-mm screen and three chemical treatments were applied to each grinding: distilled water (control); sodium hydroxide (4.5 g per 100 g cob dry matter); and Magadi soda (9.0 g per 100 g cob dry matter). Cobs were treated for 24 h using one litre of solution per kg of maize cobs.The digestion coefficient of crude protein was lowered (P< 0.01) by finer grinding of the maize cobs. Dry matter digestibility coefficients were 44.7, 54.2 and 61.6% for maize cobs treated with water, NaOH and Magadi soda, respectively. Digestibility of energy, cell walls and cellulose was increased more by Magadi soda than by NaOH. Digestibility of acid detergent fibre (ADF) was depressed (P< 0.05) by NaOH but improved (P< 0.05) by Magadi soda. Chemical treatment lowered (P< 0.01) the digestibility of crude protein from 28.0 to 17.0% (NaOH) or to 18.7% (Magadi soda). Grinding and chemical treatment of maize cobs interacted (P< 0.01) in their effects on digestibility of crude protein.Friesian cattle, grazed on a predominantly Nandi Setaria (Setaria sphacelata) and Silver Leaf Desmodium (Desmodium uncinatum) pasture, and supplemented with water-, NaOH- and Magadi soda-treated maize cobs, gained 0.41, 0.55 and 0.51 kg per day, respectively. Daily maize cob intake was higher on NaOH-treated than on water- and Magadi soda-treated cobs. Cattle on NaOH- and Magadi soda-treated cobs required more than 1 month to adapt to the cobs and show superior gain. 相似文献
997.
998.
Coronary artery aneurysms (CAA) were originally described in a series of post-mortem studies but are now more commonly observed during the widely used coronary angiography.This article reports on four adult patients with CAA associated with obstructive coronary atherosclerosis. Arterial and venous conduits were successfully performed in all four. The aetiology and treatment are discussed. 相似文献
999.
1000.
M. Bakheit Said 《Plant and Soil》1972,36(1-3):239-242
Summary Experiments were carried out to measure direct adsorption of urea in some Sudan soils and to compare two methods for controlling
urea hydrolysis.
All the soils examined showed some capacity to adsorb urea. Urea adsorption was related to both the exchange capacity and
clay content; the exchange capacity giving higher correlation than the clay content.
Both autoclaving and mercuric chloride treatments controlled hydrolysis almost completely. Autoclaving was preferred as the
method of controlling hydrolysis in this work. 相似文献