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Biomedical subjects

W A Ray

Publications and source records attributed to W A Ray.

At least 109 records · Page 6Linked to original sources
PubMed1985

Interethnic differences in genetic polymorphism of debrisoquin and mephenytoin hydroxylation between Japanese and Caucasian populations.

Interethnic differences in debrisoquin and mephenytoin hydroxylation have been compared between normal white (n = 183) and Japanese (n = 100) subjects with the 8-hour urinary metabolic ratio of debrisoquin and the urinary S/R enantiomeric ratio of mephenytoin to identify extensive (EM) and poor (PM) metabolizers. In white subjects the frequency of PMs was 8.7% and 2.7% for debrisoquin and mephenytoin, respectively. In contrast, in Japanese subjects no PMs of debrisoquin were identified, while the incidence of PMs of mephenytoin was 18%. These substantial differences (P less than 0.001) in polymorphic distributions of oxidative drug metabolizing ability have implications for interethnic efficacy and toxicity of drugs and other xenobiotics that are metabolized by the involved cytochrome P-450 isozymes.

Administration, Oral↗
PubMed1985

Factors influencing probability of reperfusion with intracoronary ostial infusion of thrombolytic agent in patients with acute myocardial infarction.

A multivariate logistic regression equation was used to evaluate variables related to successful intracoronary thrombolytic therapy. One hundred seventeen patients with a totally occluded infarct-related artery were randomly given ostial infusions of urokinase or streptokinase in a blinded study. The opening rate was 57%. The agent used and time from onset of symptoms to beginning of treatment did not significantly influence opening rate (p greater than .25). The site of occlusion was a strong predictor of opening rate (p = .0004). The anterior descending coronary artery was successfully opened more frequently than the left circumflex or right coronary artery (p = .012). Presence of collaterals adversely affected the recanalization rate in all groups (p = .0004). These variables had an additive effect on the probability of opening. Patients with proximal anterior descending occlusion and no collaterals had a 90% recanalization rate, while those with distal occlusions in vessels other than the anterior descending and with collaterals had only a 24% chance for reperfusion. Thus location of occlusion and presence or absence of collaterals may strongly influence opening rates.

Adult↗
PubMed1985

Statistical analysis for experimental models of ocular disease: continuous response measures.

Experimental designs in ophthalmologic research frequently treat both eyes of a subject in the same fashion: e.g., therapy with a specific drug or control. In these two-eye designs, observations from the same subject are often positively correlated. Failure to account for this correlation is a serious error which overstates the precision of studies, resulting in falsely significant results. This paper reviews the statistical methods appropriate for studies where endpoints are quantitative. We present: (1) the use of analysis of variance (t-test when there are 2 treatment conditions) to estimate differences between all experimental treatments, (2) the use of contrasts to estimate differences between specific treatments, and (3) methods for analysis of data from multiple experiments. Because of the ubiquity of incorrect analysis of data from two-eye designs in the ophthalmologic research literature and the serious consequences of this error, we propose a limited statistical review of manuscripts to ascertain if the statistical analysis matched the experimental design.

Amphotericin B↗
PubMed1985

Statistical analysis of multi-eye data in ophthalmic research.

An apparently common error in statistical analysis of ophthalmic data is to perform statistical tests that do not account for the correlation generally present between observations made for the right and left eyes of a subject. This error has as a consequence an overstatement of the precision of the study, resulting in incorrect P values which indicate a greater measure of statistical significance than the data warrant. As measures to reduce the occurrence of this serious error in statistical analyses, the authors recommend increased emphasis on educational programs for investigators, stimulation of nontechnical articles reviewing statistical methods, and a sharper focus upon statistical analysis in the peer review process.

Eye Diseases↗
PubMed1984

Variability in isolate recovery rates from multiple and single breeds of outbred pigmented rabbits in an experimental model of Candida keratitis.

We evaluated variability of isolate recovery rates in an experimental model of Candida keratitis for both heterogeneous, pigmented, outbred rabbits and homogeneous Dutch-belted rabbits. Our purpose was to achieve more precise evaluation of topical antifungal agents in our model by substantially reducing the component of variance due to inter-rabbit differences. For the homogeneous Dutch-belted rabbits, the overall variance was reduced by a factor of 2.34 (p = 0.18) vis a vis the heterogenous outbred rabbits. The greatest reduction, a factor of 3.5, was achieved for the inter-rabbit component of variance. The upper bound for the hereditability measure was reduced from 29% to 18%. These data suggest that (1) researchers using animal models should perform a components of variance analysis to identify the factors influencing experimental precision, and (2) for our model, additional reduction in variability must come from refinement of experimental technique.

Analysis of Variance↗
PubMed1984

Efficacy of antifungal agents in the cornea. II. Influence of corticosteroids.

The influence of topical corticosteroid on the efficacy of five topical antifungal agents was evaluated in a standardized rabbit model of Candida keratitis using a quantitative mycologic technique. Topical 1% prednisolone acetate worsened the disease when given alone and adversely influenced the efficacy of 5% natamycin, 1% flucytosine, and 1% miconazole when given in combination. The efficacy of amphotericin B appeared unaffected when the antifungal agent was administered in concentrations of 0.5% and 0.15%. The adverse effect of the topical corticosteroid appeared to be inversely related to the efficacy of the antifungal agent in vivo.

Adrenal Cortex Hormones↗
PubMed1984

Influence of the corneal epithelium on the efficacy of topical antifungal agents.

A model of deep stromal Candida albicans infection was established by injecting 25 microliters of a suspension containing 5 X 10(9) colony forming units/ml of the yeast into corneas of pigmented rabbits. In this model, the infection lasts for more than 8 days. Using quantitative techniques, the authors compared the efficacy of six topical antifungal agents in the presence of an intact epithelium and in corneas debrided of epithelium. In corneas debrided on a daily basis, the polyenes (amphotericin B 0.15% and 0.075% and natamycin 5%) exhibited a significant antifungal effect. When the epithelium was left intact, 5% natamycin and 0.075% amphotericin B were without effect, while the efficacy of the 0.15% preparation of amphotericin B was much reduced. Removal of the epithelium appeared to affect adversely the efficacy of flucytosine. The imidazoles were not efficacious in this model.

Administration, Topical↗
PubMed1984

Efficacy of antifungal agents in the cornea. IV. Amphotericin B methyl ester.

Quantitative mycologic techniques were used to evaluate the efficacy of topical amphotericin B methyl ester in two models of yeast infection in rabbit eyes. Doses of 1%, 0.5%, and 0.15% were used in a model of superficial Candida albicans infection. The 1% dose of drug was highly efficacious, abolishing the disease after 2 days of treatment. With doses of 0.5% and 0.15%, decreasing efficacy was observed. Antifungal activity did not deteriorate when 1% prednisolone acetate was administered concomitantly with the 1% dose. In a model of deep stromal infection, the administration of topical 1% amphotericin B methyl ester was highly efficacious when the corneal epithelium was absent. Even in corneas with intact epithelium, a reduced though still significant effect was noted.

Administration, Topical↗
PubMed1983

Improving antibiotic prescribing in office practice. A controlled trial of three educational methods.

We conducted a statewide controlled trial of three methods to improve antibiotic prescribing in office practice: a mailed brochure, a drug educator visit, and a physician visit. Educational topics were three antibiotics contraindicated for office practice and oral cephalosporins. Medicaid prescribing data were used to select donors who needed education. The effect of the methods was evaluated by comparing the change in prescribing (the year before the intervention v the year after the intervention) for the doctors receiving education with the prescribing of comparable doctors chosen as controls. The mailed brochure had no detectable effect, and the drug educator had only a modest effect. The physician visits produced strong attributable reductions in prescribing of both drug classes. For the contraindicated antibiotics, the reductions were 18% in number of doctors prescribing, 44% in number of patients per doctor receiving these drugs, and 54% in number of prescriptions written per doctor. For the oral cephalosporins, both number of patients and number of prescriptions per doctor were reduced by 21%. Doctors responded equally well to recommendations designed to improve the quality of care and to reduce the cost of care.

Administration, Oral↗
PubMed1983

The risk of anticholinergic toxicity in the elderly: a study of prescribing practices in two populations.

The potential for anticholinergic toxicity due to concurrent use of medications was assessed among 5,902 continuous nursing home residents and a comparable group of ambulatory patients. During the study year nearly 60% of the nursing home residents and 23% of the ambulatory patients received drugs with anticholinergic properties. Based on recommended doses of the drugs, 565 of the nursing home patients and 413 of the ambulatory patients could have received three or more anticholinergic medications concurrently. An examination of nursing home patients receiving the most frequently prescribed antipsychotic and tricyclic antidepressant drugs concurrently revealed that physicians did not choose drugs selectively within the two classes in order to minimize the potential for anticholinergic toxicity. The findings of this study suggest that the risk of anticholinergic toxicity may be underestimated by physicians.

Aged↗
PubMed1981

Clinical electroneurography: statistical analysis of controlled measures in twenty-two normal subjects.

Electroneurography, an objective electrophysiologic measurement of a muscle compound action potential, is used to assess the integrity of a peripheral motor nerve. This paper describes how to perform electroneurography with particular attention to control of patient and instrumentation variables. Twenty-two normal adult subjects were tested in a balanced, designed experiment. The resultant average difference between the right and left halves of the face was not significant. The standard deviation of this difference was divided into three components: test-retest daily, and intersubject. The data suggest that the most significant source of error in electroneurography is test-retest variability (p less than 0.05) and that repeated and averaged measures on a given patient will increase the precision of the test. As further understanding and experience are gained, electroneurography measurements should be interpreted in light of clinical findings and more traditional tests.

Action Potentials↗
PubMed1980

A study of antipsychotic drug use in nursing homes: epidemiologic evidence suggesting misuse.

We reviewed 384,326 prescriptions for 5,902 Medicaid patients residing continuously for one year in 173 Tennessee nursing homes. Of these patients, 43 per cent received antipsychotic drugs; 9 per cent were chronic recipients (received at least 365 daily doses per year). Of the 1,580 physicians who cared for these patients, 42 per cent prescribed antipsychotic medication. Physicians with large nursing home practices (10 or more patients) prescribed 81 per cent of the total antipsychotic medication, and were usually family practitioners (78 per cent) and in rural practice (47 per cent). As nursing home practice size increased, doctors prescribed more drug per patient (p less than .001). Wide variation in antipsychotic drug use occurred among nursing homes; the chronic recipient rate ranged from 0 to 46 per cent. More drug was given per patient in larger homes (r = .18, p less than .05). Typically, one physician (the "dominant" physician) provided care for the majority of a nursing home's patients. The proportion of a home's patients seen by the dominant physician was correlated with the chronic recipient rate (r = .17, p less than .05). These findings provide epidemiologic evidence suggesting misuse of antipsychotic drugs in nursing homes. They illustrate the need for investigations of techniques for patient management in nursing homes which rely less upon psychtropic drugs.

Aged↗
PubMed1978

Drug prescribing during pregnancy. A controlled study of Tennessee Medicaid recipients.

The effect of pregnancy on prescribing was assessed in a population of pregnant Medicaid recipients and two matched groups of control women. Of the 2,528 gravidas, 62 per cent received systemic legend drugs (excluding dietary supplements) during their pregnancies. White women and women 30 years of age and older were most likely to receive these medications. Systemic anti-infectives were the most frequently prescribed category of drugs (excluding dietary supplements). One fourth of the women received a narcotic-containing drug and 13 percent of the women received psychotropic drugs, most frequently diazepam. Barbiturates and narcotic-containing drugs were often "hidden" a fixed combination medication. In general, prescribing did not decrease as a result of pregnancy. This study and other studies reviewed here emphasize the need for comprehensive drug-use guidelines for physicians who care for pregnant women.

Adult↗
PubMed1978

Surveillance of antibiotic prescribing in office practice.

Using fiscal and administrative data routinely collected by the Tennessee Medicaid program, we conducted epidemiologic analyses of physicians' prescribing of selected antibiotics in office practice. This research has defined several subgroups of physicians who regularly malprescribed chloramphenicol or tetracyclines (to children less than 8 years old). After special educational mailings to all physicians, prescribing of these antimicrobial drugs diminished. Similar analyses could enable the profession to design specific remedial educational interventions, target them at physicians needing contemporary information, and assess their impact by monitoring subsequent prescribing. Such a program might diminish inappropriate drug use, reduce adverse drug reactions, help contain medical care costs, and produce better educated physicians.

Ambulatory Care↗
PubMed1977

Prescribing of tetracycline to children less than 8 years old. A two-year epidemiologic study among ambulatory Tennessee medicaid recipients.

The committee on Drugs of the American Academy of Pediatrics finds virtually no indications for administering tetracyclines to children less than 8 years old. This study analyzes tetracycline prescribing to ambulatory children less than 8 years of age in the Tennessee Medicaid program during a two-year period. Of the nearly 59,000 children in the study, 4,026 (7%) received 7,046 tetracycline prescriptions. Twenty-seven percent (527) of 1,947 participating physicians prescribed tetracycline; 26 physicians (5%) wrote 54% of the prescriptions for 45% of the children. Physicians in family practice prescribed the greatest quantity of tetracycline. Surgeons and internists prescribed more tetracycline to young children than did pediatricians. Rural location of practice was independently associated with increased tetracycline prescribing for all specialties. Recent graduates from medical school were less apt to prescribe tetracycline than were earlier graduates.

Age Factors↗