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1.
Iloprost caused a concentration-dependent decrease in the response to noradrenaline in the rabbit isolated endothelium denuded rings from superior mesenteric artery but not thoracic aorta. Similar inhibition was obtained by verapamil using identical concentrations. In Ca(2+)-free EGTA containing medium noradrenaline both at lower and higher concentrations elicited a reduced contractile response and further addition of Ca2+ (2.5 mM) to the medium produced a second contraction in both mesenteric artery and aortic rings which was significantly and equally inhibited by iloprost and verapamil using identical concentrations in mesenteric artery but not in aortic rings. Prior addition of iloprost to the medium did not protect the inhibitory effect of phenoxybenzamine against noradrenaline-induced contraction. These results were taken as an evidence for the possible Ca2+ entry reducing effect of iloprost in mesenteric artery but not thoracic aorta. These results were also taken as an indirect evidence supporting the hypothesis that increased synthesis of prostacyclin by noradrenaline in the vascular wall may inhibit the contractile effect of the agonist by a (-) feedback mechanism mediated by Ca2+ entry into the vascular smooth muscle. 相似文献
2.
Abstract A set of protein conformations are analyzed by normal mode analysis. An elastic network model is used to obtain fluctuation and cooperativity of residues with low amplitude fluctuations across different species. Slow modes that are associated with the function of proteins have common features among different protein structures. We show that the degree of flexibility of the protein is important for proteins to interact with other proteins and as the species gets more complex its proteins become more flexible. In the complex organism, higher cooperativity arises due to protein structure and connectivity. 相似文献
3.
Patterns of Root Colonization in Epacridaceous Plants Collected from Different Sites 总被引:2,自引:0,他引:2
Root colonization was studied in ten species of the Epacridaceaeat three sites in Victoria by morphological and cross-inoculationexperiments. The sites and genera chosen were Cranbourne [Epacrisimpressa Labill. andLeucopogon ericoides(Smith) R. Br.] andRye [L. parviflorus(Andrews) Lindley] on the Mornington Peninsula,and the Grampians[Astroloma conostephioides(Sond.) Benth.,A.humifusum(Cav.) R. Br.,A pinifolium(R. Br.) Benth,Brachylomadaphnoides(Smith) Benth.,E. impressa, E. impressavar.grandifloraBenth.andStyphelia adscendensR. Br.] in western Victoria. For morphologicalstudies, samples of roots from each species at each site werecleared and stained and examined microscopically. For cross-inoculationstudies, cuttings from each site were struck in potting mediuminoculated with soil from the same and other sites. The ericoidmycorrhizae in the roots of plants found at or grown in Cranbourneand Rye soils were similar. Both were significantly differentfrom the internal hyphae found in the roots of plants foundat or grown in Grampians soils, which were three times largerin diameter and formed dense coils which filled the host celland invaded adjacent epidermal cells. This suggests that morethan one fungus is involved in the relationships, that the MorningtonPeninsula sites had a different fungus from the Grampians siteand that host specificity is low. Vesicular structures werealso found commonly on plants at the Grampians site, in contrastwith other sites. Epacridaceae; root; fungus; mycorrhiza; morphology; inoculation 相似文献
4.
Ozer E Yörükoğlu K Mungan MU Ozkal S Demirel D Sağol O Kirkali Z 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》2001,23(4):251-256
OBJECTIVE: To evaluate the significance of nuclear morphometry in predicting the clinical course in superficial (pTa and pT1) bladder cancer. STUDY DESIGN: The study included 73 patients with superficial transitional cell carcinoma of the bladder who were followed for a median of 21 months (range, 1-90). Nuclear morphometry was performed by a computer-assisted image analyzer system on hematoxylineosin-stained histologic sections and characterized by five nuclear variables: area, perimeter, major and minor diameter, and form factor. Patient charts and microscopic slides were reviewed to record tumor stage, grade and size. Tumor proliferative activity was assessed by immunohistochemical staining with Ki-67 antibody. RESULTS: None of the morphometric variables showed a significant relation to tumor progression and recurrence. Higher values of mean nuclear area, perimeter, and major and minor diameter were significantly related to higher grade and proliferative activity. Mean nuclear area and minor diameter were associated with advanced stage. Of established prognostic factors, only histologic grade was significant in predicting progression. CONCLUSION: The results suggest that nuclear morphometry may be valuable in determining proliferative activity and may be well correlated with histologic grade in superficial bladder cancer. However, like many other potential prognostic factors, it seems to be unreliable in predicting clinical behavior. 相似文献
5.
Coombes JS Powers SK Hamilton KL Demirel HA Shanely RA Zergeroglu MA Sen CK Packer L Ji LL 《American journal of physiology. Regulatory, integrative and comparative physiology》2000,279(6):R2149-R2155
The purpose of these experiments was to examine the effects of dietary antioxidant supplementation with vitamin E (VE) and alpha-lipoic acid (alpha-LA) on biochemical and physiological responses to in vivo myocardial ischemia-reperfusion (I-R) in aged rats. Male Fischer-334 rats (18 mo old) were assigned to either 1) a control diet (CON) or 2) a VE and alpha-LA supplemented diet (ANTIOX). After a 14-wk feeding period, animals in each group underwent an in vivo I-R protocol (25 min of myocardial ischemia and 15 min of reperfusion). During reperfusion, peak arterial pressure was significantly higher (P < 0.05) in ANTIOX animals compared with CON diet animals. I-R resulted in a significant increase (P < 0.05) in myocardial lipid peroxidation in CON diet animals but not in ANTIOX animals. Compared with ANTIOX animals, heart homogenates from CON animals experienced significantly less (P < 0.05) oxidative damage when exposed to five different in vitro radical producing systems. These data indicate that dietary supplementation with VE and alpha-LA protects the aged rat heart from I-R-induced lipid peroxidation by scavenging numerous reactive oxygen species. Importantly, this protection is associated with improved cardiac performance during reperfusion. 相似文献
6.
Andréia S Lessa Bruno D Paredes Juliana V Dias Adriana B Carvalho Luiz Fernando Quintanilha Christina M Takiya Bernardo R Tura Guilherme FM Rezende Antonio C Campos de Carvalho Célia MC Resende Regina CS Goldenberg 《BMC veterinary research》2010,6(1):1-10
Background
Atypical scrapie was first identified in Norwegian sheep in 1998 and has subsequently been identified in many countries. Retrospective studies have identified cases predating the initial identification of this form of scrapie, and epidemiological studies have indicated that it does not conform to the behaviour of an infectious disease, giving rise to the hypothesis that it represents spontaneous disease. However, atypical scrapie isolates have been shown to be infectious experimentally, through intracerebral inoculation in transgenic mice and sheep. The first successful challenge of a sheep with 'field' atypical scrapie from an homologous donor sheep was reported in 2007.Results
This study demonstrates that atypical scrapie has distinct clinical, pathological and biochemical characteristics which are maintained on transmission and sub-passage, and which are distinct from other strains of transmissible spongiform encephalopathies in the same host genotype.Conclusions
Atypical scrapie is consistently transmissible within AHQ homozygous sheep, and the disease phenotype is preserved on sub-passage. 相似文献7.
van Beers JJ Raijmakers R Alexander LE Stammen-Vogelzangs J Lokate AM Heck AJ Schasfoort RB Pruijn GJ 《Arthritis research & therapy》2010,12(6):R219
Introduction
Rheumatoid arthritis (RA) frequently involves the loss of tolerance to citrullinated antigens, which may play a role in pathogenicity. Citrullinated fibrinogen is commonly found in inflamed synovial tissue and is a frequent target of autoantibodies in RA patients. To obtain insight into the B-cell response to citrullinated fibrinogen in RA, its autoepitopes were systematically mapped using a new methodology. 相似文献8.
9.
Murat Ayaz Nizamettin Dalkilic Hulagu Bariskaner Seckin Tuncer Ilhami Demirel 《Biological trace element research》2007,116(3):301-309
Gender differences are related to the manner in which the heart responds to chronic and acute stress conditions of physiological
and pathological nature. Depending on dose, sodium selenite acts as an antioxidant proven to have beneficial effects in several
pathological conditions G. Drasch, J. Schopfer, and G. N. Schrauzer, Selenium/cadmium ratios in human prostates: indicators
of prostate cancer risk of smokers and non-smokers, and relevance to the cancer protective effects of selenium,Biol. Trace Element Res.
103(2), 103–107 (2005); R. G. Kasseroller and G. N. Schrauzer, Treatment of secondary lymphedema of the arm with physical decongestive
therapy and sodium selenite: a review,Am. J. Ther.
7(4), 273–279 (2000); G. N. Schrauzer, Anticarcinogenic effects of selenium,Cell. Mol. Life Sci.
57(13–14), 1864–1873 (2000); I. S. Palmer and O. E. Olson, Relative toxicities of selenite and selenate in the drinking water of rats,J. Nutr.
104(3), 306–314 (1974). To date, little is known about the gender-dependent direct effects of toxic doses of selenite on electrophysiology
of the cardiovascular system H. A. Schroeder and M. Mitchener, Selenium and tellurium in rats: effect on growth, survival
and tumors,J. Nutr.
101(11), 1531–1540 (1971); G. N. Schrauzer, The nutritional significance, metabolism and toxicology of selenomethionine,Adv. Food Nutr. Res.
47, 73–112 (2003). In the present study, the effects of in vitro toxic concentrations of sodium selenite ranging from 10-6 M to 10-3 M were tested on both male and female rat heart preparations. The toxic effects seen in an electrocardiogram and left ventricular
pressure were dose and sex dependent at most of the tested concentrations. The present study clearly shows that at toxic doses,
stress conditions are induced by selenite, resulting in gender-dependent modifications of the heart function. This modification
is more pronounced in the contraction cascade of female rats. Males, on the other hand, had been much more affected in excitation-related
parameters. 相似文献