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排序方式: 共有162条查询结果,搜索用时 15 毫秒
1.
Cardiac and coronary consequences of intracoronary platelet activating factor infusion in the domestic pig 总被引:4,自引:0,他引:4
In previous studies we have shown that platelet-activating factor (PAF) is a potent vasoactive substance with deleterious effects on coronary blood flow (CBF) and myocardial performance. The present study further investigates the effects of PAF during its sustained intracoronary infusion in the blood-perfused domestic pig (n = 16). PAF infusion (1-9 nmol/min) produced triphasic changes in CBF (n = 7): an initial brief phase of coronary dilation (14 +/- 2% above baseline), followed by severe reduction in CBF due to increase in coronary vascular resistance and a third phase of escape that was characterized by return of CBF towards baseline in spite of continuing PAF infusion. In 9 remaining pigs PAF infusion had a biphasic response: the first phase of coronary dilation rapidly turned into severe coronary constriction accompanied by severe systemic hypotension and death within a few min. PAF infusion caused a profound rise in systemic arterial and coronary venous thromboxane B2 levels, while 6-keto-PGF1 alpha and leukotriene C4-immunoreactivity levels were not changed. Indomethacin completely blocked the rise in thromboxane level during PAF infusion and abolished the constrictor effect of PAF on the coronary vessels. These data suggest that PAF might play a detrimental role on the coronary circulation and cardiac function, primarily through thromboxane A2 mediated mechanism. 相似文献
2.
A total of 54 ovariectomized female guinea pigs were divided into three groups and tested six times at 2-week intervals for their responsiveness to exogenous ovarian hormones (3 days of 4 micrograms/kg estradiol benzoate plus 1 day of 0.4 mg/kg progesterone) or control injections (0.2 ml oil vehicle). Two weeks after ovariectomy, treatment with estradiol significantly reduced food intake and body weight, and also produced vaginal membrane rupture in 98.1% of the females. When tested for sexual behavior at 4, 6, and 8 hr after the progesterone injection, 29 of the subjects (53.7%) displayed lordosis in response to manual stimulation. Twelve weeks after ovariectomy, the effects of estradiol on food intake, body weight, and vaginal membrane condition had not diminished. However, the overall proportion of females from which lordosis could be elicited declined to 27.8%. Biweekly injections of estradiol benzoate plus progesterone to one of the groups of females did not prevent this decline in the sexual response. Based on these results, it was concluded that the observed reduction in behavioral lordosis does not represent a general decline in the responsiveness of ovariectomized guinea pigs to estrogenic stimulation, but may involve changes in their responsiveness to progesterone or in other mechanisms more specifically associated with sexual behavior. 相似文献
3.
4.
Nataliya Di Donato Ying Y. Jean A. Murat Maga Briana D. Krewson Alison B. Shupp Maria I. Avrutsky Achira Roy Sarah Collins Carissa Olds Rebecca A. Willert Agnieszka M. Czaja Rachel Johnson Jessi A. Stover Steven Gottlieb Deborah Bartholdi Anita Rauch Amy Goldstein Victoria Boyd-Kyle Kimberly A. Aldinger Ghayda M. Mirzaa Anke Nissen Karlla W. Brigatti Erik G. Puffenberger Kathleen J. Millen Kevin A. Strauss William B. Dobyns Carol M. Troy Robert N. Jinks 《American journal of human genetics》2016,99(5):1117-1129
5.
Deborah F. Tate Leslie Lytle Kristen Polzien Molly Diamond Kelsey R. Leonard John M. Jakicic Karen C. Johnson Christine M. Olson Kevin Patrick Laura P. Svetkey Rena R. Wing Pao‐Hwa Lin Mathilda Coday Melissa N. Laska Gina Merchant Sara J. Czaja Richard Schulz Steven H. Belle 《Obesity (Silver Spring, Md.)》2019,27(7):1085-1098
6.
7.
Factors affecting the yield and properties of bacterial cellulose 总被引:12,自引:0,他引:12
Krystynowicz A Czaja W Wiktorowska-Jezierska A Gonçalves-Miśkiewicz M Turkiewicz M Bielecki S 《Journal of industrial microbiology & biotechnology》2002,29(4):189-195
Acetobacter xylinum E25 has been applied in our studies in order to find optimal culture conditions for effective bacterial cellulose (BC) production.
The strain displays significantly higher stability in BC production under stationary culture conditions. In contrast, intensive
agitation and aeration appear to drastically reduce cellulose synthesis since such conditions induced formation of spontaneous
cellulose nonproducing mutants (Cel−), which dominated in the culture. Mutation frequency strictly depends on the medium composition in agitated cultures. Enrichment
of the standard SH and Yamanaka media with 1% ethanol significantly enhanced BC production in stationary cultures. Horizontal
fermentors equipped with rotating discs or rollers were successfully applied in order to improve culture conditions. Relatively
slow rotation velocity (4 rpm) and large surface area enabling effective cell attachment are optimal parameters for cellulose
production. Physical properties of BC samples synthesized either in stationary cultures or in a horizontal fermentor revealed
that cellulose from stationary cultures demonstrated a much higher value of Young's modulus, but a much lower value of water-holding
capacity. Journal of Industrial Microbiology & Biotechnology (2002) 29, 189–195 doi:10.1038/sj.jim.7000303
Received 01 March 2002/ Accepted in revised form 18 July 2002 相似文献
8.
Wasowicz K Kaleczyc J Sienkiewicz W Czaja K Zivcik A Lakomy M 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2001,39(3):269-274
The influence of an anti-GnRH vaccine on VIP- and NPY-positive innervation of testes was studied in the pig. The immunization prevented the occurrence of changes in the pattern of VIP- and NPY-positive testicular innervation associated with the sexual maturation: it maintained the density of innervation at the high level characteristic for sexually immature animals. The effect was dependent on the method of immunization: the application of two doses of the vaccine was more efficient than application of only one dose, and vaccination with adjuvant was more efficient than vaccination with the plain vaccine. The studies on VIP and NPY concentration in the testicular tissue with radioimmunoassay (RIA) revealed immunization-dependent changes in the peptide concentration, however, some discrepancies between morphological changes and peptide levels were observed. 相似文献
9.
Matthew Kennedy Lian Yu Maria João Lima Carla S. Ascenso Christopher Czaja Isabel Moura Jose J. G. Moura F. Rusnak 《Journal of biological inorganic chemistry》1998,3(6):643-649
Desulforedoxin and the N-terminus of desulfoferrodoxin share a 36 amino acid domain containing a (Cys-S)4 metal binding site. Recombinant forms of desulforedoxin, an N-terminal fragment of desulfoferrodoxin, and two desulforedoxin
mutant proteins were reconstituted with Fe3+, Cd2+, and Zn2+ and relative metal ion affinities assessed by proton titrations. Protons compete with metal for protein ligands, a process
that can be followed by monitoring the optical spectrum of the metal-protein complex as a function of pH. For all polypeptides,
Fe3+ bound with the highest affinity, whereas the affinity of Zn2+ was greater than Cd2+ in desulforedoxin and the N-terminal fragment of desulfoferrodoxin, but this order was reversed in desulforedoxin mutant
proteins. Metal binding in both mutants was significantly impaired. Furthermore, the Fe3+ complex of both mutants underwent a time-dependent bleaching process which coincided with increased reactivity of cysteine
residues to Ellman's reagent and concomitant metal dissociation. It is hypothesized that this results from an autoredox reaction
in which Fe3+ is reduced to Fe2+ with attendant oxidation of ligand thiols.
Received: 17 June 1998 / Accepted: 3 September 1998 相似文献
10.
Jennifer MP Woo Zhuofeng Lin Mohamad Navab Casey Van Dyck Yvette Trejo-Lopez Krystal MT Woo Hongyun Li Lawrence W Castellani Xuping Wang Noriko Iikuni Ornella J Rullo Hui Wu Antonio La Cava Alan M Fogelman Aldons J Lusis Betty P Tsao 《Arthritis research & therapy》2010,12(3):R93