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141.
Jeff W. Stevens Yasuteru Oike Christopher Handley Vincent C. Hascall Anne Hampton Bruce Caterson 《Journal of cellular biochemistry》1984,26(4):247-259
A ternary complex of hyaluronic acid-binding region and link protein bound to hyaluronic acid was isolated from limit clostripain digests of proteoglycan aggregates isolated from the Swarm rat chondrosarcoma. Under these conditions, the hyaluronic acid-binding region has a molecular weight of ? 65,000 (HA-BR65). N-terminal amino acids in the complex were selectively l4C-carbamylated. The resulting derivatized HA-BR65 was isolated, and tryptic peptide maps were prepared and developed on two-dimensional TLC sheets. A single, labeled peptide was obtained which gave a Mr by ? 8,000 by SDS-PAGE. Chymotrypsin digestion of the ternary complex reduced the molecular weight of HA-BR65 to a polypeptide of ? 55,000 (HA-BR55) which still retains the same N-terminal tryptic peptide. Partial digestion of proteoglycan aggregates with clostripain generated a series of larger intermediates with the hyaluronic acid-binding region. Direct SDS-PAGE analysis revealed one major intermediate with Mr ? 109,000 (HA-BR109) as well as HA-BR65. After chondroitinase digestion, two additional prominent intermediates were observed on a SDS-PAGE gel at Mr ? 120,000 (HA-BR120) and ? 140,000 (HA-BR140). All the intermediates were recognized by a monoclonal antibody specific for the hyaluronic acid-binding region, and all of them contained the same N-terminal tryptic peptide. The results indicate that the N terminus of the core protein is at the hyaluronic acid-binding end of the proteoglycan and that the chondroitin sulfate chains are first present on the core protein in a region between 109,000 and 120,000 molecular weight away from the N terminus. 相似文献
142.
The formation of thromboxane A2 by phospholipase A2 in rat platelets is inhibited by nicotinic acid. The synthesis of PGE2 and PGF2α is increased.Nicotinic acid inhibits collagen-induced aggregation in rat platelets. 相似文献
143.
144.
Mycoplasma Phosphoenolpyruvate-Dependent Sugar Phosphotransferase System: Purification and Characterization of Enzyme I 下载免费PDF全文
The Mycoplasma phosphoenolpyruvate-dependent sugar phosphotransferase system consists of three components: a membrane-bound enzyme II, a soluble phosphocarrier protein (HPr), and a soluble enzyme I. The soluble enzyme I was purified by ammonium sulfate fractionation; Bio-Gel P-10 gel filtration; acid precipitation; diethylaminoethyl-Bio-Gel A; and Bio-Gel HTP column chromatography. The enzyme I was shown to be homogeneous by electrophoresis in a pH 8.9 non-sodium dodecyl sulfate gel and by isoelectric focusing. Whereas the protein moved as a single component in both the non-sodium dodecyl sulfate gel and isoelectric focusing, on sodium dodecyl sulfate gels, it moved as three subcomponents. The molecular weights of the three subunits, alpha, beta, and gamma, were 44,500, 62,000 and 64,500, respectively. The holoprotein moved as a single component, in the region of 220,000 daltons, in a Bio-Gel A 0.5-agarose column. The molar ratio of subunits was estimated to be 2alpha:1beta:1gamma. The elution characteristics on a diethylaminoethyl column at pH 7.4 and 6.8, acid precipitation data, and amino acid composition indicated that the protein is acidic. Isoelectric focusing occurred at pH 4.8. N-terminal amino acids determined by the dansyl chloride method indicated that glycine, alanine, and tyrosine are N-terminal amino acids of the three subunits. Although the protein was stable for at least 14 months at -20 degrees C, it was irreversibly inactivated by the thiol reagent N-ethyl-maleimide. 相似文献
145.
Michel Hughes Daniéle Duval Heidy Schmid Patrick Kitabgi Michel Lazdunski Jean-Pierre Vincent 《Life sciences》1982,31(5):437-443
This paper describes the interaction of apamin, the bee venom neurotoxin, with its receptor in the guinea pig colon. The pharmacological activity of the toxin was assayed by measuring its contracting effect on guinea pig colon preparations that had been previously relaxed by neurotensin. The IC50 value of apamin in this bioassay is 7 nM. These pharmacological data are compared to the binding properties of apamin to smooth muscle membranes prepared from guinea pig colon. The highly radiolabeled monoiododerivative of apamin binds to its colon receptor with a dissociation constant . The maximal binding capacity of colonic membranes is 30dfmol/mg of protein. The dissociation constant of the unmodified toxin is 23 pM. The difference between the toxin concentrations that produce half-maximal effects in the binding and pharmacological studies arises from the different experimental conditions used for the two assays. 相似文献
146.
Sidney H. Rosenberg Vincent Fausone Robert Clark 《The Western journal of medicine》1980,133(4):292-296
The estrogen component in oral contraceptives is generally thought to increase the risk of stroke in users as compared with controls. If this were true, an increased risk for stroke also should be seen among postmenopausal women using estrogens as compared with nonusers. To test this hypothesis, the charts of 198 postmenopausal patients who had had strokes were compared with those of 396 controls for estrogen use and for the associated risk factors of diabetes, hypertension and coronary artery disease. The difference between estrogen use in the study population versus controls proved not significant, and the use of estrogens did not significantly influence the distribution of the above risk factors. We concluded that the use of estrogens in physiological replacement doses does not increase the risk of stroke in postmenopausal women. 相似文献
147.
Vincent W. Ogundero 《Mycopathologia》1980,71(1):9-11
Nine species of thermophilic fungi were obtained from retailed packets of imported and locally manufactured brands of cigarettes and from cured tobacco leaves. They include known human pathogens such asThermoascus aurantiacus Miehesensu Apinis,Mucor pusillus Lindt andMucor miehei Cooney and Emerson.
Chaetomium thermophile La Touche,Humicola insolens Cooney and Emerson,Thermoascus crustaeus (Apinis and Chesters) Stolk andMucor miehei have not been previously reported on tobacco products.Fewer species were obtained from foreign cigarettes than from locally manufactured brands. A mean moisture content of 19% was recorded for imported cigarettes and 37% for Nigerian brands. The potential health hazards posed to man by the unrestricted use of tobacco products are discussed. 相似文献
148.
A comparison was made between two methods for collecting gastric secretion in the rat. The two included a pyloric ligation technique and a snare-type pyloric cuff which was surgically implanted 2 weeks before the collection was initiated. It was hypothesized that the surgical trauma associated with pyloric ligation would inhibit gastric secretion and thus yield smaller gastric samples with this procedure as compared to the cuff technique. No differences in volume of gastric secretion or total acid output were observed between the two methods. 相似文献
149.
Three assays for nitrogen demand were compared on samples ofnatural plankton and on green and blue-green algal species inculture. The most reliable guide was selective luxury uptakeof nitrogen by the plankton after enrichment with a 10-to-1(wt/wt) mixture of inorganic N and P. Ammonium transport capacity,measured either directly (cultures) or by Vmax for uptake ofthe NH4+ analogue methylammonium (lakewaters), was generallyhigh in lakewaters with low dissolved inorganic N-to-P ratiosand in N-deficient cultures of green algae. By contrast, transportcapacity was much reduced in both natural and cultured populationsof heterocystous blue-green algae growing under conditions oflow combined inorganic nitrogen. Ammonium enhancement assays(heterotrophic CO2, fixation after NH4+ enrichment) were conductedat monthly intervals on eutrophic Lake Rotorua. There was astrong, negative correlation between this indicator of N deficiencyand dissolved inorganic N-to-P ratios below a threshold of 6:1.Ammonium enhancement was not, however, a reliable indicatorof combined inorganic N-demand by populations of heterocystousblue-green algae. All three assays provided strong evidenceof a persistent shortage of nitrogen relative to phosphorusfor algal production in Lake Rotorua. 相似文献
150.
Henry R. Black Samuel O. Thier Philip F. Felig James F. Jekel Joseph Belsky James L. Bernene Everett Cooper Vincent A. De Luca Jr. Martin H. Floch Marvin Garrell Pasquale E. Perillie Robert L. Piscatelli George F. Thornton 《The Yale journal of biology and medicine》1977,50(6):637-644
In July, 1975, the Departments of Internal Medicine at the Yale University School of Medicine and eight community hospitals in southern and western Connecticut formed the Yale Affiliated Hospital Program (YAHP) in Internal Medicine. The YAHP provides a planned and focused program of continuing education for medical staff and housestaff at the affiliated hospitals. Six formats for the over 1,000 rounds, lectures, and conferences given annually are used. The members of the YAHP also cooperate in housestaff and faculty recruiting, evaluation of quality of care and evaluation of the process of continuing medical education itself. This report summarizes the organization, goals and future plans of the YAHP. 相似文献