Biomedical subjects

N Dawson

Publications and source records attributed to N Dawson.

8 recordsLinked to original sources

PubMed1992

Suramin: a novel growth factor antagonist with activity in hormone-refractory metastatic prostate cancer.

PURPOSE: Suramin is known to inhibit the growth of malignant prostate carcinoma cells in vitro. This led us to evaluate the effectiveness of suramin in the treatment of 38 patients with prostate carcinoma refractory to hormone therapy. PATIENTS AND METHODS: Suramin was administered by continuous infusion at a rate designed to reach a peak of 300 micrograms/mL at the end of 14 days. Patients were given 8 weeks to recover from any toxicity before beginning the second cycle. Subsequent cycles were administered in the same manner except the starting dose rate was 280 mg/m2. RESULTS: In 17 patients with measurable soft tissue disease, three had complete disappearance of soft tissue disease for 4, 5, and 11 months, whereas three patients had a greater than or equal to 50% decrease in the sum of the products of the diameters of all measurable disease for greater than or equal to 1 month. Of these 17 patients, pretreatment prostate-specific antigen (PSA) decreased by 75% or more in five (29%) and normalized in one (6%). The remaining 21 patients had disease limited to bone, and only one of these experienced resolution of more than 50% of all lesions on bone scan. Of these 21 patients, pretreatment PSA decreased by 75% or more in eight (38%) and normalized in five (25%). Median time to progression for all patients was 26.3 weeks, and median survival was 42.3 weeks. Patients with bone involvement alone exhibited a better survival than patients with soft tissue involvement (P2 = .02). Survival was strongly correlated (P2 = .0001) with a decline in the pretreatment PSA of greater than or equal to 75% by the eighth week on therapy, with nearly an 85% survival at 1 year compared with a 20% survival for those whose pretreatment PSA did not decline by that amount. CONCLUSION: We conclude that suramin is an active agent in hormone-refractory prostate carcinoma.

Aged↗

PubMed1991

Comparison of physician judgment and decision aids for ordering chest radiographs for pneumonia in outpatients.

STUDY OBJECTIVES: To compare physician judgment in the use of chest radiographs for diagnosing pneumonia with decision rules developed by Diehr, Singal, Heckerling, and Gennis. DESIGN: Propsective observational investigation with preradiograph survey of physicians' intent to order chest radiographs for patients presenting with respiratory complaints. All patients had uniform clinical data collected, including chest radiographs and sufficient information to retrospectively apply the four clinical prediction rules. SETTING: The emergency department and medical outpatient clinic of a major urban teaching hospital. PARTICIPANTS: Adult patients presenting with recent history of acute cough or exacerbation of chronic cough plus either fever, sputum production, or hemoptysis. RESULTS: Of 290 patients, 21 (7%) had pneumonia. The sensitivity of physician judgment (0.86) exceeded that of all four decision rules. The specificity of the Diehr (0.67), Heckerling (0.67), and Gennis (0.76) rules exceeded that of physician judgment (0.58). The accuracy of the Gennis (0.76) and Heckerling (0.68) rules also exceeded that of the physicians (0.60). DISCUSSION: Physicians' diagnostic and therapeutic decisions were characterized by high sensitivity but lower specificity for ordering chest radiographs to diagnose pneumonia. The higher specificity and accuracy of two of the decision rules suggest that they may have a role in patient evaluation.

Adult↗

PubMed1991

Chemotherapy of disseminated Merkel-cell carcinoma.

Six patients developed metastatic merkel-cell carcinoma and were treated with a combination chemotherapy frequently used for small-cell lung cancer. Five of six patients had a complete response for a median of 3.5 months. Overall survival from initiation of chemotherapy was a median of 6.5 months. Two patients died from major complications of therapy.

Adult↗

PubMed1991

Health indicators 1991.

This is the second edition of a database developed by the Canadian Centre for Health Information (CCHI). It features 49 health indicators, under one cover containing the most recent data available from a variety of national surveys. This information may be used to establish health goals for the population and to offer objective measures of their success. The database can be accessed through CANSIM, Statistics Canada's socio-economic electronic database and retrieval system, or through a personal computer package which enables the user to retrieve and analyze the 1.2 million data points in the system.

Canada↗

PubMed1989

Consider TMJ.

Explore the source record for details and available documents.

Humans↗

PubMed1987

Fluorescent labeling of bacteriorhodopsin: implications for helix connections.

Purple membrane from Halobacterium halobium was reacted with dansyl (5-dimethylamino-1-naphthalenyl fluorescent labels that have specificity for different protein side chains of bacteriorhodopsin. Dansyl chloride was found to react primarily with Lys-41. Dansyl hydrazine was coupled, with water-soluble carbodiimide, to Glu-74 and/or Asp-85, which was the major modified site after papain-cleavage of the carboxyl-terminal 17 amino acids. Fluorescence energy transfer was used to probe the proximity of the modified sites to the retinal chromophore of bacteriorhodopsin. The dansyl group on Lys-41 was greater than 2.99 nm from retinal, while the dansyl group on Glu-74/Asp-85 was greater than 2.10 nm from retinal. Information available on the location of retinal in the transmembrane profile and probable surface locations of the fluorescent labels was combined with the energy transfer results to calculate distances projected in the plane of the membrane. The projected distances to retinal were 1.64 nm (Lys-41) and 1.65 nm (Gly-74). These measurements, combined with many other labeling experiments that have been reported, restrict the number of likely helix-connection models to only three: EDCABGF, FEDCBAG and FGEABDC (in the nomenclature of Engelman et al. (1980) Proc. Natl. Acad. Sci. USA 77, 2023-2027).

Bacteriorhodopsins↗

PubMed1986

Hours of contact and their relationship to students' evaluations of teaching effectiveness.

This study was designed to determine if hours of contact with a teacher influenced a student's perceptions of teaching effectiveness. Three hundred forty-one nursing students used a researcher developed instrument to rate five teachers of nursing on classroom teaching effectiveness, and one of the five teachers on clinical teaching effectiveness. Results indicated that a positive relationship existed between students' ratings of their clinical teacher's teaching effectiveness in the classroom and clinical area. The significant Pearson correlations for the five teachers ranged from .61 to .91 (p = .000). The hypothesis, that increased contact hours with a teacher would have a positive influence on students' evaluations of a teacher, received support. Three of five clinical groups of students gave their clinical instructors significantly higher scores for classroom teaching effectiveness than did other students.

Education, Nursing, Baccalaureate↗

PubMed1986

Automated fluorescent analysis for drug-induced cytotoxicity assays.

The human tumor clonogenic assay has been reported to predict for sensitivity of human tumors to a variety of drugs. However, this assay requires large numbers of viable cells, is time-consuming, and takes at least 2 weeks before results are available. To circumvent these problems, Weisenthal developed a microscope-based dye exclusion assay. Because this method is also time-consuming and subject to observer error, we have developed an automated method of quantitating drug cytotoxicity using a flow cytometric cell sorter (FCM). After incubation of drug-exposed tumor cells, acetaldehyde-fixed duck red blood cells (DRBC) are added. Dead tumor cells and the fixed DRBC are stained by the fluorescent dye propidium iodide, which penetrates dead cell membranes. A two-parameter analysis (cell size as measured by narrow angle light scatter vs propidium iodide fluorescence) enables determination of the live tumor cell:DRBC ratio. There was a strong correlation between the FCM method and manual counting (r = 0.958 for cell lines, r = 0.831 for fresh leukemic cells, P less than 0.0001 in both cases). We conclude that the automatized FCM method gives compatible results to the manual dye exclusion assay and increases efficiency.

Adult↗