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71.
The effect of FR 7534, a new dihydropyridine CA2+ antagonist, nitroglycerin, and dipyridamole have been compared on coronary collateral function in pentobarbital-anesthetized open-chest dogs following acute ligation of the left anterior descending coronary artery. Measurements of tissue blood flow using radioactive microspheres were made 60 min postligation after low and high doses of each drug and at the higher dose with methoxamine added to to return mean aortic pressure. FR 7534 treatment increased subepicardial, subendocardial, and transmural tissue flow by 100% in the central ischemic zone when perfusion pressure was controlled by methoxamine. Nitroglycerin also increased ischemic tissue flow, but to a lesser degree, 18% transmurally. Dipyridamole produced no significant change. Tissue flow in normal myocardium was similarly increased by FR 7534 and dipyridamole but slightly reduced by nitroglycerin. FR 7534 and nitroglycerin also increased retrograde coronary pressure when aortic presure was maintained constant. FR 7534, but not nitroglycerin, increased ischemic contractile force. In this model, FR 7534 may produce greater effects than nitroglycerin in increasing blood supply to ischemic myocardium delivered by endogenous collaterals especially when aortic perfusion pressure was controlled. 相似文献
72.
J Brunton D Hinde C Langston R Gross B Rowe M Gurwith 《Journal of clinical microbiology》1980,11(4):343-348
During epidemiological studies carried out in urban and rural areas of the midwestern Canadian province of Manitoba, we cultured enterotoxigenic Escherichia coli (ETEC) from 16 (1.7%) of 945 diarrheal stools and 4 (0.3%) of 1,282 normal stools. ETEC was found in not more than 2.3% of diarrheal stools obtained from any population during any season. Diarrhea associated with ETEC persisted for a mean of 9 days. Two children were dehydrated and required intravenous fluid therapy, and one adult suffered a cholera-like syndrome. Half of the children required hospitalization for management of their diarrhea. Two adults and two children who harbored ETEC were completely asymptomatic. The pattern of toxin production correlated with serotype and the serotypes encountered were (with a few exceptions) similar to those found in other areas. We conclude that ETEC is an uncommon cause of diarrhea, both in rural and urban areas of central Canada. However, the possibility that ETEC might cause severe sporadic cases or epidemics of gastroenteritis remains. 相似文献
73.
R. Finke R. Gross E. Hackenthal J. Huber H. R. Kirchheim 《Pflügers Archiv : European journal of physiology》1983,399(2):102-110
- The effect of varying renal artery pressure between 160 and 40 mm Hg on renal blood flow and renin release was studied in seven conscious foxhounds under β-adrenergic blockade receiving a normal sodium diet (4.1 mmol/kg/day). Pressure was either increased by bilateral common carotid occlusion or reduced in steps and maintained constant by a control-system using an inflatable renal artery cuff. Carotid occlusion itself had no influence on renal blood flow and renin release when renal artery pressure was kept constant and the β-receptors in the kidney were blocked.
- Between 160 mm Hg and resting pressure there was no change in renal blood flow; between resting blood pressure and the lower limit of autoregulation (average 63.9 mm Hg) renal blood flow increased slightly (average 7%) indicating a high efficiency of renal blood flow autoregulation.
- The relationship between renal artery pressure and renin release could be approximated by two linear sections:a low sensitivity to a pressure change (average slope: ?0.69 ±0.26ng AI/min/mm Hg) was found above a threshold pressure (average: 89.8±3.3 mm Hg) and a high sensitivity to a pressure change (average slope: ?64.4±20.8 ng AI/ min/mm Hg) was observed between threshold pressure and 60 mm Hg. There was no further increase of renin release between 60 and 40 mm Hg.
- It is concluded that within the autoregulatory plateau the kidney of a conscious β-blocked dog receiving a normal sodium diet releases only negligible amounts of renin until renal artery pressure falls below a threshold pressure of 90 mm Hg which is close to the animals resting systemic pressure. Since beyond that a decrease of systemic pressure by as little as 1.3 mm Hg below threshold can raise resting renin release (84.8±29.8 ng/min) by 100%, it is suggested that systemic blood pressure tends to stabilize at a level at which renin release is minimal.
74.
Differentiation between mouse-virulent and -avirulent strains of Toxoplasma gondii by a monoclonal antibody recognizing a 27-kilodalton antigen. 总被引:1,自引:1,他引:1 下载免费PDF全文
Using a murine monoclonal antibody, we were able to differentiate between mouse-virulent and -avirulent strains of Toxoplasma gondii. Monoclonal antibody TB6G5 was reactive with eight clinical mouse-avirulent isolates but not with mouse-virulent laboratory strains RH and BK. The antibody-reactive antigen was identified by indirect immunofluorescence and immunoblot as a 27-kDa cytoplasmic protein expressed by tachyzoites as well as by bradyzoites. 相似文献
75.
Colonization and maintenance of murine embryonic stem cells on poly(alpha-hydroxy esters) 总被引:2,自引:0,他引:2
Harrison J Pattanawong S Forsythe JS Gross KA Nisbet DR Beh H Scott TF Trounson AO Mollard R 《Biomaterials》2004,25(20):4963-4970
The aim of this study was to determine the ability of various poly(alpha-hydroxy esters) to support the in vitro propagation of murine embryonic stem (ES) cells in an undifferentiated state. To this end, ES cell colonization, growth and Oct-4 immunoreactivity following a 48 h culture period upon poly((D,L)-lactide), poly((L)-lactide), poly(glycolide) and poly((D,L)-lactide-co-glycolide) (PLGA) were assessed. By the analysis of live and dead cell number indices and Oct-4 immunoreactivity, ES cell colonization rate during a 48 h culture period was found to be significantly greater on PLGA compared to all the other unmodified poly(alpha-hydroxy esters) tested. Surface treatment of all polymers with 0.1m potassium hydroxide revealed a significant increase in ES cell live numbers when compared to all unmodified polymers, thus revealing a correlation between polymer content, hydrophilicity and colonization rate. These data suggest that surface treated poly(alpha-hydroxy esters) may be employed for ES cell scale up procedures and in tissue engineering applications requiring the colonization of scaffolds by ES cells in an undifferentiated state. According to such applications, once the designated scaffold has been colonized, ES cell directed differentiation into the desired and fully differentiated, functional adult tissue may then be effected. 相似文献
76.
Toxoplasma gondii is able to invade phagocytic cells of the monocyte-macrophage lineage and replicates within a parasitophorous vacuole. Since macrophages may activate specific T lymphocytes by presenting pathogen-derived antigens in association with molecules of the MHC, we investigated the in vitro expression of host cell molecules involved in antigen processing and presentation before and during infection of murine bone marrow-derived macrophages (BMM) with T. gondii. Fifty-one hours after addition of T. gondii tachyzoites at different parasite-to-host ratios, up-regulation of total MHC class II molecules by interferon-gamma (IFN-γ) was dose-dependently abrogated in up to 50% of macrophages compared with uninfected control cultures. Quantitative analyses by flow cytometry revealed that the IFN-γ-induced surface expression of class II antigens as well as the IFN-γ-induced up-regulation of class I molecules was significantly decreased in T. gondii-infected macrophage cultures compared with uninfected controls. However, the constitutive expression of MHC class I antigens was not altered after parasitic infection, and infected BMM remained clearly positive for these molecules. After infection of macrophages preactivated with IFN-γ for 48 h, T. gondii also actively down-regulated an already established expression of MHC class II molecules. Furthermore, kinetic analysis revealed that the reduction in intracellular and plasma membrane-bound class II molecules started ≈ 20 h after infection. While MHC class II antigens were most prominently reduced in parasite-positive host cells, culture supernatant from T. gondii-infected BMM cultures also significantly inhibited expression of these molecules in uninfected macrophages. However, down-regulation of MHC class II molecules was not mediated by an increased production of prostaglandin E2, IL-10, transforming growth factor-beta or nitric oxide by infected BMM compared with uninfected controls. Our data indicate that intracellular T. gondii interferes with the MHC class I and class II antigen presentation pathway of murine macrophages and this may be an important strategy for evasion from the host's immune response and for intracellular survival of the parasite. 相似文献
77.
Immunochemical analysis of plasmid-encoded proteins released by enteropathogenic Yersinia sp. grown in calcium-deficient media. 总被引:13,自引:15,他引:13 下载免费PDF全文
Enteropathogenic Yersinia sp. releases plasmid-associated proteins of low molecular mass (26-67 kilodaltons) at 37 degrees C. In this study, the optimum conditions for the release of proteins were assessed and the released proteins (RPs) were analyzed for the manner of release, immunochemical characteristics, and the location of the genes necessary for their synthesis. Protein release was strongly enhanced when growth media were markedly depleted of calcium ions by precipitation with oxalate or chelation with EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid]. RP yields were greatest when Yersinia spp. were in the exponential growth phase. The RPs appeared to be released from the Yersinia spp. by secretion rather than by pinching off of membrane vesicles, because the RPs did not sediment during high-speed centrifugation nor were they contaminated to any significant degree with lipopolysaccharide. Moreover, immunoblot analysis revealed only traces of protein species related to RPs within the outer membranes of plasmid-positive Yersinia spp. grown at 37 degrees C under calcium-restricted conditions. Immunoblot studies also showed that the RPs of Y. enterocolitica serotypes O:3, O:8, and O:9 and the RP of Y. pseudotuberculosis serotype I are highly cross-reactive. Finally, the immunoprecipitates of the products of minicells which harbor Yersinia plasmids were used to demonstrate that at least three proteins immunochemically related to the released fraction were plasmid encoded. These results suggest that at least three of the RPs may be related to or identical with previously described plasmid-encoded Yersinia outer membrane proteins. 相似文献
78.
在这篇论文中,我们提出了用于选择视觉的数据和智能控制的动态网络系统的神经实现过程。模型由数个相互作用的子系统构成,用于不同的处理。所有的神经子系统与信息和控制流程的倒序和顺序紧密相关。 相似文献
79.
W J Shih K Gross B Mitchell J Collins B Wierzbinski S Magoun U Y Ryo 《Journal of the National Medical Association》1992,84(12):1049-1050
To evaluate a relationship between Gleason scores of histopathology of prostate carcinoma and concurrent serum prostate-specific antigen (PSA) and prostate acid phosphatase (PAP) values, 65 men with prostate carcinoma were studied. These patients' cumulative Gleason scores were obtained by totaling the primary and secondary patterns, resulting in two groups: 42 patients received high (6-10) and 23 received low (2-5) Gleason scores. Serum PSA and PAP values were measured by radioimmunometric assay 1 to 7 days before surgical procedures or biopsy for prostate carcinoma. Mean serum PSA for patients in the high Gleason score group was 134.39 ng/mL (normal range: 0 to 4), and the mean serum PSA for patients in the low Gleason score group was 23.62 ng/mL. Mean serum PAP for patients with high scores was 28.08 ng/mL (normal range: 0 to 5), and the mean serum PAP for patients with low scores was 18.19 ng/mL. Patients with high Gleason scores showed significantly greater elevation of serum PSA than those with low Gleason scores (P = .047), using two samples to test for groups having unequal variants. Prostate acid phosphatase levels of patients with high scores were not significantly higher than the levels in patients with low scores (P = .60). These results indicate that PSA levels but not PAP levels correlate with Gleason scores. 相似文献
80.
Andrea M. Gross Megan Frone Karen W. Gripp Bruce D. Gelb Lisa Schoyer Lisa Schill Beth Stronach Leslie G. Biesecker Dominic Esposito Edjay Ralph Hernandez Eric Legius Mignon L. Loh Staci Martin Deborah K. Morrison Katherine A. Rauen Pamela L. Wolters Dina Zand Frank McCormick Sharon A. Savage Douglas R. Stewart Brigitte C. Widemann Marielle E. Yohe 《American journal of medical genetics. Part A》2020,182(4):866-876
RASopathies caused by germline pathogenic variants in genes that encode RAS pathway proteins. These disorders include neurofibromatosis type 1 (NF1), Noonan syndrome (NS), cardiofaciocutaneous syndrome (CFC), and Costello syndrome (CS), and others. RASopathies are characterized by heterogenous manifestations, including congenital heart disease, failure to thrive, and increased risk of cancers. Previous work led by the NCI Pediatric Oncology Branch has altered the natural course of one of the key manifestations of the RASopathy NF1. Through the conduct of a longitudinal cohort study and early phase clinical trials, the MEK inhibitor selumetinib was identified as the first active therapy for the NF1‐related peripheral nerve sheath tumors called plexiform neurofibromas (PNs). As a result, selumetinib was granted breakthrough therapy designation by the FDA for the treatment of PN. Other RASopathy manifestations may also benefit from RAS targeted therapies. The overall goal of Advancing RAS/RASopathy Therapies (ART), a new NCI initiative, is to develop effective therapies and prevention strategies for the clinical manifestations of the non‐NF1 RASopathies and for tumors characterized by somatic RAS mutations. This report reflects discussions from a February 2019 initiation meeting for this project, which had broad international collaboration from basic and clinical researchers and patient advocates. 相似文献