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排序方式: 共有1194条查询结果,搜索用时 31 毫秒
1.
Luis Hernandez-Garcia Gregory R Lee Alberto L Vazquez Chun-Yu Yip Douglas C Noll 《Magnetic resonance in medicine》2005,54(4):955-964
A new approach to modeling the signal observed in arterial spin labeling (ASL) experiments during changing perfusion conditions is presented in this article. The new model uses numerical methods to extend first-order kinetic principles to include the changes in arrival time of the arterial tag that occur during neuronal activation. Estimation of the perfusion function from the ASL signal using this model is also demonstrated. The estimation algorithm uses a roughness penalty as well as prior information. The approach is demonstrated in numerical simulations and human experiments. The approach presented here is particularly suitable for fast ASL acquisition schemes, such as turbo continuous ASL (Turbo-CASL), which allows subtraction pairs to be acquired in less than 3 s but is sensitive to arrival time changes. This modeling approach can also be extended to other acquisition schemes. 相似文献
2.
Starting from 4,4'-diamino-diphenylsulfone (DDS) as a lead structure, new 2-substituted analogues as well as new 2-substituted 4-alkylamino-4'-amino diphenylsulfones have been designed and synthetized in different ways. This has led to compounds the inhibitory activity of which against 7,8-dihydropteroic acid synthase of plasmodia and mycobacteria is clearly superior to that of sulfadoxine and in most cases to that of DDS. Of special interest is 4'-amino-4-n-propylamino-2-methyl-diphenylsulfone. Together with inhibitors of 7,8-dihydrofolate reductase in vitro and in vivo it possesses a marked synergistic inhibitory activity against plasmodia. In contrast to DDS in doses up to 200 mg/kg p.o. (cat) no methemoglobin formation is observed. The compound has been selected for further studies. 相似文献
3.
Peer relationships and adjustment in children with cancer 总被引:4,自引:4,他引:0
R B Noll S LeRoy W M Bukowski F A Rogosch R Kulkarni 《Journal of pediatric psychology》1991,16(3):307-326
Evaluated the psychosocial adaptations of children with cancer (n = 24, ages 8-18) as compared with same classroom controls on indices of (a) peer- and self-perceptions of sociability, aggression, and social isolation; (b) overall popularity; (c) mutual friendships; (d) feelings of loneliness; and (e) self-concept in multiple domains. Although the peer report data showed that children with cancer had a social reputation as significantly more socially isolated, no significant differences were found for their popularity, number of mutual friends, loneliness, or self-worth. Findings suggest that children with cancer have a reputation as more socially isolated, but differences were not found on measures of acceptance by peers, self-concept, or loneliness. 相似文献
4.
Dr. Hajo Dirk Weitmann Tomas Hendrik Knocke Claudia Waldhäusl Richard Pötter 《Strahlentherapie und Onkologie》2006,182(2):86-95
BACKGROUND: In advanced vaginal recurrences of cervical and endometrial carcinomas therapeutic options are rare because of preceding therapy. PATIENTS AND METHODS: 23 patients developing advanced vaginal recurrences of cervical and endometrial carcinomas were included. 15 patients started with external-beam therapy to the pelvis and eight patients after preceding radiotherapy underwent brachytherapy alone. All patients had ultrasound-guided implantation of transvaginal or transperineal interstitial needles for brachytherapy. Median prescribed total dose was 64 Gy. RESULTS: 18 patients (78%) achieved complete remission. Six patients are alive without tumor and one with tumor after a median follow-up of 64 months. 14 patients died of tumor and two of intercurrent disease. 5-year disease-specific survival and local control rate were 43% and 47%, respectively, in patients with complete remission. Univariate analysis found time to relapse > 2 years, initial diameter < or = 4 cm, initial volume < 15 cm(3), no extension to the pelvic side wall, volume before brachytherapy < 7.5 cm(3), brachytherapy coverage index > 0.8, and prescribed total dose > 64 Gy being positive predictors for local control and survival. CONCLUSION: The use of ultrasound guidance for placement of interstitial needles in template-based brachytherapy of advanced recurrent gynecologic malignancies is a feasible, safe, and cheap method with encouraging results. Today, ultrasound imaging can be also used to some extent for treatment planning which requires further development. Patient- and treatment-related prognostic factors can be defined. 相似文献
5.
Essential hypertension is associated with reduced endothelium-dependent vasodilation, mainly due to reduced nitric oxide and an increase in vasoconstrictors such as endothelin-1 and angiotensin II. Endothelial dysfunction has been shown to be associated with an increased incidence of cardiovascular events and to have prognostic significance. The reduction of blood pressure per se is insufficient for improving endothelial function, and antihypertensive drugs show contrasting effects in terms of improvement or restoration of endothelial function. 相似文献
6.
Steven D. Forman Jonathan D. Cohen Mark Fitzgerald William F. Eddy Mark A. Mintun Douglas C. Noll 《Magnetic resonance in medicine》1995,33(5):636-647
The typical functional magnetic resonance (fMRI) study presents a formidable problem of multiple statistical comparisons (i.e, > 10,000 in a 128 x 128 image). To protect against false positives, investigators have typically relied on decreasing the per pixel false positive probability. This approach incurs an inevitable loss of power to detect statistically significant activity. An alternative approach, which relies on the assumption that areas of true neural activity will tend to stimulate signal changes over contiguous pixels, is presented. If one knows the probability distribution of such cluster sizes as a function of per pixel false positive probability, one can use cluster-size thresholds independently to reject false positives. Both Monte Carlo simulations and fMRI studies of human subjects have been used to verify that this approach can improve statistical power by as much as fivefold over techniques that rely solely on adjusting per pixel false positive probabilities. 相似文献
7.
K L?ster S Seidel D Kirstein F Schneider F Noll 《Journal of immunological methods》1992,148(1-2):41-47
Novel kinds of magnetizable particles have been prepared using the interaction between the complexing groups of phosphonic acid and polyvalent metal ions on the surface of Fe3O4 particles. After modification of monoclonal and polyclonal antibodies by the bifunctional chelating agent 2-(4-diazophenyl)-1-hydroxyethane-1,1-bisphosphonic acid, antibodies were immobilized at a ratio of 5-10 mg antibody molecules per ml Fe3O4 particles without loss of immunological reactivity. Very sensitive and fast immunoenzymometric assays for the quantitative determination of human interferon-alpha 1 and mouse immunoglobulins were developed using such particles. The advantages of the method include immobilization of proteins on magnetizable carriers without chemical modification of the carrier and the short assay time compared to conventional immunoenzymometric assays. 相似文献
8.
O. Bertel G. Noll 《Cardiovascular drugs and therapy / sponsored by the International Society of Cardiovascular Pharmacotherapy》1988,2(1):107-111
Summary In a prospective single-blind study we examined the effects of additional molsidomine in 20 patients (63±10 years; 15 males, 5 females) with unstable resting angina (3 attacks/24 hours) refractory to triple therapy (nitrates, calcium antagonists, and beta blockers) combined with heparin or aspirin. All but one patient had coronary artery disease documented by coronarography (n=17) or by recent myocardial infarction (n=3). Two patients had angiographically documented severe coronary spasms. Patients entered the study if coronary bypass surgery or PTCA could not be performed within 3 days after angiography (n=9) or was not feasible due to anatomical or technical reasons (n=6), concomitant malignant disease (n=2), or age greater than 75 years (n=3). All patients received molsidomine orally 12 to 24 mg/day. In 15 of the 20 patients molsidomine was given i.v. initially, starting with 20 mg i.v., followed by infusion of 1 to 4 mg/hour. Heart rate and blood pressure did not change significantly, and eight patients had a slight decrease of systolic and diastolic blood pressure. Severe adverse effects did not occur, and moderate headaches were reported by five patients. In 13 patients, unstable angina could be stabilized, and they remained free of resting angina; five had a marked reduction of the frequency of anginal attacks. In two patients, molsidomine was without demonstrable beneficial effects. After a follow-up of 4 weeks, nine patients were free of symptoms after bypass surgery or PTCA, 10 continued to have angina NYHA class II or III, and one patient died due to acute myocardial infarction and cardiogenic shock 4 days after starting additional molsidomine. We conclude that molsidomine is well tolerated and has a marked beneficial effect in patients with refractory unstable angina. Molsidomine should therefore be considered for routine therapy of unstable angina, especially in those patients who are suspected of tolerance to nitrate therapy. 相似文献
9.
C N Coleman L Noll A E Howes J R Harris J Zakar R A Kramer 《International journal of radiation oncology, biology, physics》1989,16(4):1085-1087
To exploit both the oxygen-mimetic and "pre-incubation" or continuous exposure effects of the 2-nitroimidazole radiosensitizers, we are conducting a Phase I trial of continuous infusion SR 2508 for patients receiving brachytherapy. Following the administration of a loading dose of 2 g/m2, SR 2508 is administered by continuous infusion for 48 hr. Twenty-one patients have completed treatment. The initial total dose was 8 g/m2 with patients currently receiving 15 g/m2. No toxicity has been observed. At the higher doses the steady-state plasma concentrations have been between 50 and 70 micrograms/ml. It is not yet known whether or not hypoxic sensitizers will be of benefit clinically, and if so, when during a course of treatment is the optimal time to use them. Given the lack of toxicity and plasma concentrations achievable with continuous infusion, future studies will be conducted using SR 2508 during both the external beam and brachytherapy aspects of treatment. 相似文献
10.
Gerhardt CA Vannatta K McKellop JM Taylor J Passo M Reiter-Purtill J Zeller M Noll RB 《Journal of pediatric psychology》2003,28(4):275-279
OBJECTIVE: To evaluate predictions from professionals in pediatric rheumatology regarding the child-rearing practices of caregivers of children with juvenile rheumatoid arthritis (JRA) and healthy classmates. METHODS: Sixteen professionals identified items from the Child-Rearing Practices Report (CRPR) that were expected to differentiate between caregivers of children with JRA (64 mothers, 45 fathers) and caregivers of healthy classmates (64 mothers, 40 fathers). Families were interviewed, and physician ratings of disease severity were obtained. RESULTS: Experts predicted difficulties in protectiveness, discipline, and worry. Ratings from parents of children with JRA showed modest agreement with the professionals, surprising similarity to controls, and a limited association with disease factors. CONCLUSIONS: Contrary to expert opinion, JRA has only a modest influence on some child-rearing practices. Educating health care providers may minimize misperceptions about caring for children with JRA, and screening parents of children with more severe disease may assist in allocating education and services for families. 相似文献