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Biomedical subjects

S Workman

Publications and source records attributed to S Workman.

At least 19 recordsLinked to original sources
PubMed2001

Electrochemiluminescence of copper(I) bis(2,9-dimethyl-1,10- phenanthroline).

The electrochemical and electrochemiluminescence (ECL) properties of Cu[dmp]2+ (dmp = 2,9-dimethyl-1,10-phenanthroline) have been investigated. ECL has been observed for Cu(dmp)2+ in aqueous, nonaqueous, and mixed solvent solutions using tri-n-propylamine as an oxidative-reductive coreactant. The ECL intensity peaks at potential corresponding to oxidation of both the coreactant and Cu(dmp)2+. The peak potential corresponding to maximum ECL emission is approximately 500 mV more anodic than corresponding oxidative peak potentials, indicating that the ECL emission may be due to the formation of either the *Cu(dmp)2+ metal-to-ligand charge-transfer excited state or an excited-state product of Cu(dmp)2+ oxidation. ECL efficiencies (phiecl = photons generated per redox event) are solvent-dependent (phiecl (CH3CN) > phiecl (50:50 (v/v) CH3CN:H20) > phiecl (H2O)) and correspond fairly well with photoluminescence efficiencies. Increased ECL efficiencies (> or = 50-fold) are observed in the presence of the nonionic surfactant Triton X-100.

Copper↗
PubMed2001

Surfactant chain length effects on the light emission of tris(2,2'-bipyridyl)ruthenium(II)/ tripropylamine electrogenerated chemiluminescence.

The effects of nonionic surfactant chain length on the properties of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3(2+) where bpy = 2,2'-bipyridine) electrochemiluminescence (ECL) have been investigated. The electrochemistry, photophysics, and ECL of Ru(bpy)3(2+) in the presence of a series of nonionic surfactants are reported (Triton X-100, 114, 165, 405, 305, and 705-70). These surfactants differ in the number of poly(ethylene oxide) units incorporated into the surfactant molecule. The anodic oxidation of Ru(bpy)3(2+) produces ECL in the presence of tri-n-propylamine (TPrA) in aqueous surfactant solution. Increases in ECL efficiency (> or = 5-fold) and TPrA oxidation current (> or = 2-fold) have been observed in surfactant media. Slight decreases in ECL intensity are observed as the chain length of the nonionic surfactant increases. The data supports adsorption of surfactant on the electrode surface, thus facilitating TPrA and Ru(bpy)3(2+) oxidation and leading to higher ECL efficiencies.

Journal Article↗
PubMed2001

Hospital policy on appropriate use of life-sustaining treatment. University of Toronto Joint Centre for Bioethics/Critical Care Medicine Program Task Force.

OBJECTIVE: To describe the issues faced, and how they were addressed, by the University of Toronto Critical Care Medicine Program/Joint Centre for Bioethics Task Force on Appropriate Use of Life-Sustaining Treatment. The clinical problem addressed by the Task Force was dealing with requests by patients or substitute decision makers for life-sustaining treatment that their healthcare providers believe is inappropriate. DESIGN: Case study. SETTING: The University of Toronto Joint Centre for Bioethics/Critical Care Medicine Program Task Force on Appropriate Use of Life-Sustaining Treatment. PARTICIPANTS: The 24-member Task Force included physician and nursing leaders from five critical care units, bioethicists, a legal scholar, a health administration expert, a social worker, and a hospital public relations professional. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Our specific lessons learned include a) a policy focus on process; b) use of a negotiation and mediation model, rather than a hospital ethics committee model, for this process; and c) the policy development process is itself a negotiation, so we recommend equal involvement of interested groups including patients, families, and the public. CONCLUSIONS: This article describes the key issues faced by the Task Force while developing its policy. It will provide a useful starting point for other groups developing policy on appropriate use of life-sustaining treatment.

Hospital Administration↗
PubMed2000

The effects of nonionic surfactants on the tris(2,2'-bipyridyl)ruthenium(II)--tripropylamine electrochemiluminescence system.

The electrochemistry and electrogenerated chemiluminescence (ECL) of Ru(bpy)3(2+) (bpy = 2,2'-bipyridyl) were studied in the presence of the nonionic surfactants Triton X-100, Thesit, and Nonidet P40. The anodic oxidation of Ru(bpy)3(2+) produces ECL in the presence of tri-n-propylamine in both aqueous and surfactant solutions. Increases in both ECL efficiency (> or =8-fold) and duration of the ECL signal were observed in surfactant media. A shift to lower energies of the Ru(bpy)3(2+) ECL emission by approximately 8 nm was also observed. The one-electron oxidation of Ru(bpy)3(2+) to Ru(bpy)3(3t) occurs at + 1.03 V vs Ag/AgCl in aqueous buffered (0.2 M potassium phosphate) solution as found by square wave voltammetry. This potential did not shift in surfactant systems, indicating that the redshifts in ECL emission are due to stabilization of ligand pi* orbitals in the metal-to-ligand charge-transfer excited state. These results are consistent with hydrophobic interactions between Ru(bpy)3(2+) and the nonionic surfactants.

Journal Article↗
PubMed1999

Chronic liver disease in central Harlem: the role of alcohol and viral hepatitis.

For reasons not yet determined, chronic liver disease (CLD) has been a leading cause of excess morbidity and mortality in central Harlem. We conducted a case series and case-control analysis of demographic, clinical, epidemiological, and alcohol-intake-related information from patients with CLD and age- and sex-matched hospitalized control patients. Patients' sera were tested for markers of viral hepatitis. The presumed etiology of CLD among case-patients was as follows: both alcohol abuse and hepatitis C virus (HCV) infection, 24 persons (46% of case-patients); alcohol abuse alone, 15 (29%); HCV infection alone, 6 (12%); both alcohol abuse and chronic hepatitis B virus (HBV) infection, 3 (6%); and 1 each (2%) from: 1) schistosomiasis, 2) sarcoidosis, 3) unknown causes, and 4) alcohol abuse, chronic HBV, and HCV combined. In the case-control analysis, patients who had both alcoholism and either HBV (odds ratio [OR]: 6.3; 95% CI: 0. 5-334) or HCV (OR: 2.9; 95% CI: 1.3-6.2) were at increased risk for CLD, whereas patients who had only one of these three factors were not at increased risk for CLD. Patients who tested positive for the hepatitis G virus (HGV) did not have a significantly increased risk of CLD, and neither severity of CLD nor mortality was greater among these patients. Most patients in central Harlem who had CLD had liver damage from a combination of alcohol abuse and chronic viral hepatitis. Alcohol and hepatitis viruses appear to be synergistically hepatotoxic; this synergy appears to explain both the high rate of CLD in central Harlem and the recent reductions in this rate. Persons at risk for chronic HBV and HCV infection should be counseled about their increased risk of CLD if they consume excessive alcohol. Morbidity and mortality from liver disease could be decreased further by a reduction in alcohol consumption among persons who have chronic HBV and HCV infection, avoidance of needle sharing, and hepatitis B vaccination.

Adult↗
PubMed1998

Bioethics for clinicians: 16. Dealing with demands for inappropriate treatment.

Demands by Patients or their Families for treatment thought to be inappropriate by health care providers constitute an important set of moral problems in clinical practice. A variety of approaches to such cases have been described in the literature, including medical futility, standard of care and negotiation. Medical futility fails because it confounds morally distinct cases: demand for an ineffective treatment and demand for an effective treatment that supports a controversial end (e.g., permanent unconsciousness). Medical futility is not necessary in the first case and is harmful in the second. Ineffective treatment falls outside the standard of care, and thus health care workers have no obligation to provide it. Demands for treatment that supports controversial ends are difficult cases best addressed through open communication, negotiation and the use of conflict-resolution techniques. Institutions should ensure that fair and unambiguous procedures for dealing with such cases are laid out in policy statements.

Adult↗
PubMed1997

The application of meta-analysis in assessing racial differences in the effects of antihypertensive medication.

Meta-analysis is an important technique for synthesizing research findings. Although the statistical foundations of meta-analysis continue to be debated, few question its value as a rigorous framework for organizing literature reviews. In recent years, there has been increasing emphasis on the use of meta-analysis not only to summarize the central tendency of findings but also to explain variation between studies. This article reviews the major steps in a meta-analysis with an emphasis on comparative analysis of subgroups of studies. A meta-analysis of the antihypertensive efficacy of calcium channel blockers is used to illustrate how a comparative analysis can be applied to investigate racial variation in the effects of calcium channel blockers. A statistically significant trend is found between the proportion of African-American hypertensive subjects and the mean reduction in blood pressure. Meta-analytic techniques also are applied to explore possible confounders due to differences in research design and patient characteristics.

Age Factors↗
PubMed1995

Antibiotic production and biocontrol activity by Bacillus subtilis CL27 and Bacillus pumilus CL45.

Bacillus subtilis CL27 and B. pumilus CL45 showed similar activity against Botrytis cinerea in in vitro plate assays. In a seedling bioassay, however, B. subtilis CL27 had activity similar to a commercial fungicide while B. pumilus CL45 failed completely to prevent seedling damping-off caused by Bot. cinerea. Antibiotic production by the two Bacillus strains was found to depend on the growth substrate and highest antibiotic production was found on media based on homogenized cabbage tissue. Antibiotic activity was found to depend on the pH and nutrient concentration in the assay medium. Antifungal antibiotics produced by B. subtilis CL27 and B. pumilus CL45 in different fermentation media were separated by thin layer chromatography. As suspected from the activity spectrum, three antibiotics (one with activity against Alternaria brassicicola, one with activity against Botrytis cinerea and one with activity against both fungi) could be detected in the fermentation broth of CL27, but only one in the fermentation broth of CL45. The two antibiotics produced by strain CL27 with activity against A. brassicicola were identified as peptides since their bands on the TLC plates developed a green to blue/green colour after treatment with 4,4'-tetramethyldiamino-diphenylmethane (TDM) reagent. The third antibiotics produced by strain CL27 and antibiotic produced by CL45 had a similar Rf-value and appeared not to be peptides based on the reaction with TDM. However, they showed a slightly different activity spectrum when tested against a range of different fungi. Antibiotic production was clearly indicated as the mode of action of in vivo biocontrol by strain CL27 against damping off caused by Bot. cinerea of Astilbe micro-plants, because a u.v.-induced antibiotic negative mutant strain CL27b showed no activity in seedling bioassays in vivo. Also the mutant strain CL27a which produced the two peptide antibiotics but had lost the ability to produce the non-peptide antibiotic, showed greatly reduced in vivo activity.

Antibiosis↗
PubMed1993

Academic detailing: a model for in-office CME.

The National Cancer Institute (NCI), in its goal to reduce cancer mortality by 50% by the year 2000, has placed a special emphasis on prevention and early detection, especially in underserved populations. Check-Up On Health is a community based health education program being carried out by Fox Chase Cancer Center in three inner city Philadelphia neighborhoods, to improve the provision of appropriate cancer screening and prevention services to older, blue-collar adults by their primary care physicians. Primary care physicians in the chosen neighborhoods were targeted to receive a brief cancer prevention educational message delivered by project staff and patterned on the model of drug detailing developed by the pharmaceutical industry. This study represents an attempt to evaluate the feasibility and acceptability of such an approach aimed at improving cancer prevention promotion in the health care system. Primary care physicians were identified by community residents who attended one of 67 Check-Up On Health education presentations about cancer prevention at churches, social clubs, and senior-citizen centers within the targeted neighborhoods. An attempt was then made by project staff to visit each identified physician in his/her office or clinic, during office hours, both to conduct a brief survey and to deliver an educational message about either cancer screening guidelines or counseling for smoking cessation. The physicians were also provided with educational materials for themselves as well as their patients. Twelve months after the visit, a follow-up phone call to the physicians assessed the impact of the visit and solicited suggestions for future outreach efforts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗