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Biomedical subjects

J J Koval

Publications and source records attributed to J J Koval.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effects of adding C-19 versus C-21 progestin to conjugated estrogen in moderately hypercholesterolemic postmenopausal women.

OBJECTIVE: Our purpose was to compare the effects on fasting plasma lipoprotein lipids of adding low dosage C-19 continuous progestin (dl-norgestrel) versus conventional low-dosage continuous C-21 progestin (medroxyprogesterone acetate) to cyclic conjugated estrogen therapy. STUDY DESIGN: Nine hypercholesterolemic postmenopausal women with intact uteri were randomly assigned in a prospective, double-blind, two-period crossover study of conjugated estrogen plus either (1) dl-norgestrel (0.05 mg/day) or (2) medroxyprogesterone acetate (2.5 mg/day) for 1 year and after an appropriate washout period were switched to the alternative regimen for another year. Four subjects received conjugated estrogen only. RESULTS: Compared with baselines, each of the C-19 and C-21 progestin regimens significantly increased plasma high-density lipoprotein cholesterol (15% vs 12%) and reduced the ratio of total cholesterol/high-density lipoprotein cholesterol (20% vs 15%, respectively), but only the former significantly reduced plasma triglycerides (24% vs 0.3%, p < 0.05). CONCLUSIONS: Low dosages of either dl-norgestrel (C-19) or medroxyprogesterone acetate (C-21) when combined with conjugated estrogen significantly improve plasma lipoprotein lipids of postmenopausal women.

Cholesterol↗
PubMed1997

Nonresponse bias in a survey of Ontario dentists' infection control and attitudes concerning HIV.

OBJECTIVE: This study investigated late response and nonresponse bias in an HIV-related survey of dentists. METHODS: Questionnaires with ID numbers were mailed to all dentists in Ontario (N = 5,997) with additional mailings four and seven weeks later. RESULTS: Proportionately more respondents who returned questionnaires less than four weeks after the first mailing reported that they knowingly treated (P < .05) or were willing to treat HIV-infected patients (P < .05); that they had an accurate perception of risk of HIV infection after a needlestick injury (P < .01), and preferred not to refer HIV-infected patients (P < .01). Linear extrapolation of cumulative percent responses indicated nonresponse bias in terms of attitude and knowledge items; however, the magnitude was low. CONCLUSIONS: The effects of late response and nonresponse bias on the results of this study were small. However, these results cannot be generalized beyond the study population, and obtaining high response rates and testing for nonresponse bias in surveys of attitudes related to HIV are recommended.

Acquired Immunodeficiency Syndrome↗
PubMed1997

A model of oxygen transport capacity changes for independently living older men and women.

The purpose of the present investigation was to describe, for a subset of a large random survey of men and women, restricted to the ages of 55 to 85 years, the physiological decay pattern for aerobic fitness and contributing factors of cardiovascular and pulmonary function. The time course of the age-related changes in maximal oxygen uptake (VO2max), ventilatory threshold (TVE), maximal ventilation (VEmax), maximal heart rate (HRmax), and O2 pulse (VO2max/HRmax) were examined by fitting the data to a decaying exponential model by use of a least-squares parameter estimation technique. The time constant (tau) was used to describe the rate of decline. The women showed a much slower decline in VO2max (tau = 47.4 years) and TVE (tau = 83.3 years) than the men (tau = 20.8 and 15.4 years, respectively). There was a significant age-related decrease in body weight (0.45 kg.yr-1) in the men, whereas the women showed no change. Pulmonary function did not limit performance based on the very slow decline in VEmax and the normal FEV1.0. The decay in HRmax was better described by a linear model, resulting in an extremely slow tau. Maximal O2 pulse clearly exhibited an exponential decay, with a shorter tau (tau men = 13.5 years; tau women = 28.5 years) than any other variable.

Aged↗
PubMed1997

The relationship of cigarette prices and no-smoking bylaws to the prevalence of smoking in Canada.

OBJECTIVES: The aim of this study was to analyze the association of cigarette prices and no-smoking bylaws with the prevalence of smoking. METHODS: Data on individual smoking status were taken from two national household surveys in Canada. Current cigarette price, the 1-year and 10-year increase in price, and the extent of local restrictions on public smoking were added to the model. Logistic regression was used to estimate the odds of being a smoker. RESULTS: The odds ratio for being a smoker was 1.21 where no-smoking by-laws were relatively infrequent and 1.26 when cigarettes were relatively inexpensive, after adjusting for individual age, sex, education, and marital status. CONCLUSIONS: Both cigarette prices and no-smoking bylaws are effective in controlling smoking; either alone will likely have less impact than the two measures together.

Adult↗
PubMed1996

Changes in dentists' infection control practices, knowledge, and attitudes about HIV over a 2-year period.

OBJECTIVE: To investigate changes in the infection control practices, attitudes, and knowledge of dentists as they relate to HIV/AIDS: STUDY DESIGN: A comparison of responses to surveys conducted in 1992 (n = 258) and 1994 (n = 262) with the use of univariate/multivariate analyses and McNemar's test for paired data. RESULTS: The response rate were > 70%. There were significant increases in reports of continuing education related to HIV/AIDS, heat sterilization of handpieces, use of masks, and knowledge of risk of HIV infection after a needlestick injury. Significantly fewer respondents reported concerns about staff fears about HIV/AIDS: Reports of willingness to treat patients with HIV increased from 68% to 77%. The best predictors of willingness to treat changed from primarily infection control variables to lack of concern with respect to risk or loss of patients when treating persons with HIV. CONCLUSIONS: Increased use of infection control procedures and knowledge may be partly attributable to the introduction of mandatory continuing education in 1993.

Analysis of Variance↗
PubMed1996

Therapeutics and inflammatory bowel disease: a guide to the interpretation of randomized controlled trials.

Randomized controlled trials are the optimal means of assessing the efficacy of new treatments. This report reviews the methodology of clinical trials in inflammatory bowel disease using examples from recent randomized trials of therapy for Crohn's disease and other gastrointestinal diseases to show key principles. Guidelines for the practicing clinician to evaluate these studies are provided.

Guidelines as Topic↗
PubMed1995

Randomized trial of partial zona dissection for male infertility.

OBJECTIVES: To compare IVF rates using partial zona dissection versus zona intact insemination in couples with male infertility. To analyze pregnancy rates relative to sperm characteristics, fertilization rates, and treatment. DESIGN: Randomized prospective comparison of fertilization in sibling oocytes. Transfer of the three best quality embryos from one or both treatments. SETTING: Department of Gynaecology and Reproductive Medicine, University Hospital, London, Ontario, Canada. PARTICIPANTS: Thirty-two couples undergoing IVF with a principal diagnosis of male infertility. INTERVENTION: Treatment with partial zona dissection. MAIN OUTCOME MEASURES: Fertilization and pregnancy. RESULTS: Fertilization rates were 26% and 9% after partial zona dissection and IVF, respectively. Polyspermy was < 1% in each treatment. There were five singleton pregnancies in 29 completed cycles, three in cycles with fertilization only by partial zona dissection and two in cycles with both partial zona dissection and IVF fertilization. There were no pregnancies after fertilization by IVF only. Stepwise logistic regression analysis indicated that pregnancy was related to partial zona dissection, initial sperm concentration, and total acrosin activity. CONCLUSION: Partial zona dissection was associated with minimal polyspermic fertilization and higher normal fertilization rates than sibling oocytes treated by modified IVF. Pregnancy occurred only after transfer of embryos from partial zona dissection or combined partial zona dissection and IVF.

Adult↗
PubMed1994

Ventilatory response to exercise in men and women 55 to 86 years of age.

This study examines the relationship between minute ventilation (VE) and carbon dioxide production (VCO2) during exercise in men (n = 128) and women (n = 96), 55 to 86 yr of age. The means for the slopes of VE-VCO2 (delta VE/delta VCO2), examined for graded exercise below the ventilation threshold (TVE), increased significantly for men (p < 0.0001), from 25.0 +/- 0.7 (SEM) at mean age 58 (55 to 59) yr to 32.2 +/- 1.8 at mean age 83 (80 to 86) yr, but did not change for women (p = 0.0812), from 22.3 +/- 0.9 at mean age 58 (56-59) yr to 24.2 +/- 2.4 at mean age 79 (75 to 85) yr. A correlation that was significantly greater than zero was found between delta VE/delta VCO2 and age. The increase in delta VE/delta VCO2 was 0.29/yr for men (r = 0.47, p < 0.001) and 0.20/yr for women (r = 0.28, p = 0.0051). In both cases, the explained variance was small (men = 22%; women = 8%). VE, tidal volume (VT), and breathing frequency (fb) were examined at VCO2 = 1.0 L/min, the highest intensity that most older men and women could exercise without exceeding TVE. VE was significantly higher by 14% in men 80 to 86 yr of age (38.2 +/- 1.4 L/min) compared with men 55 to 59 yr of age (33.5 +/- 0.8), whereas there were no differences in VE for the women.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Age and sex effects on mobility of the human ankle.

We investigated whether values for passive resistive torque, dorsiflexion strength, and active mobility of the ankle joint varied with age in a randomly selected sample of middle-aged and elderly males and females. The main effects of sex and age group were significant, without an interaction effect, on values for passive resistive torque and voluntary strength. The trends indicated that females had lower values for both variables and that passive torque increased and strength decreased with respect to age. Dorsiflexion range of motion also showed a highly significant trend to decrease across age groups, and more so for females than males. Mean values for middle-aged men vs old men went from 20.0 to 13.5 degrees, while corresponding values for women decreased from 20.7 degrees of dorsiflexion to 10.1. Functional ankle movement thus becomes limited with age, but could be improved by strengthening weak dorsiflexor muscles.

Aged↗
PubMed1992

Forced expiratory volume, height, and demispan in Canadian men and women aged 55-86.

In a random cross-sectional study in London, Canada, forced expiratory volume in 1 second (FeV1.0), height, and demispan (fingerweb to central sternal notch) were measured on 182 men and 212 women of mean ages 70.4 (SD 8.5) and 71.3 (8.2). The mean FeV1.0 for men was 2.55 (0.66) l, and for women 1.80 (0.48) l and declined 29 ml.year-1 and 25 ml.year-1, respectively. The mean FeV1.0 standardized for measured height and calculated height for men was 2.54 (0.61) l and 2.55 (0.62) l in men, and 1.80 (0.46) l and 1.79 (0.45) l in women. There was no significant difference between the two methods of standardization, and the relationship of height to demispan in this independent elderly population was constant across age for both men (2.16) and women (2.17). Linear and proportional regression coefficients to predict FeV1.0 from height and demispan have been generated for this random sample aged 55 to 86 years.

Aged↗
PubMed1992

Response rates in a survey of physical capacity among older persons.

A representative sample of 420 subjects aged 55 to 84 was sought for participation in a study of the relationship between physical activity and health. A stratified random sample with 35 subjects in each of 12 age-gender categories was designed, using lists generated consecutively until the target number for each category was reached. Although the protocol required walking and treadmill tests, 60.3 percent of those eligible participated, a figure comparable to that of NHANES II and superior to that of the Canada Fitness Survey. Participants were younger, more likely to be male, less likely to be currently married, and more likely to have had a white-collar job and some postsecondary education than were nonparticipants. Difficulties of obtaining subjects and methods for avoiding these difficulties include offering many opportunities to attend and determining accurately the reason for nonparticipation.

Age Factors↗
PubMed1984

Testing the effect of sex differences on sib-sib correlations.

Procedures for testing the effect of sex differences on sib-sib correlations are studied. It is demonstrated that a simple procedure for testing the equality of a pair of brother-brother and sister-sister correlations (the modified Z test) is comparable in power to the likelihood ratio test in moderately large samples drawn from sibship-size distributions that are likely to occur in practice. In small samples, the modified Z test is preferable to the likelihood ratio test, since the latter tends to be anti-conservative.

Biometry↗
PubMed1983

Clinical correlates of the spectrum of lung microvascular injury in human noncardiac edema.

We measured the clearance from blood to pulmonary edema fluid of a small molecular weight hydrophilic radiotracer, Indium-111-DTPA (In-DTPA) and a larger molecular weight radiotracer, Iodine-125-HSA (I-HSA), in patients with pulmonary edema on either a cardiac or noncardiac (permeability) basis. In previous investigations, we had noted an apparent relationship between the magnitude of clearance of I-HSA across the alveolocapillary membrane and the severity of noncardiac pulmonary edema. In this study, we were able to distinguish at least 2 distinct groups of patients with noncardiac pulmonary edema. Patients with the greatest damage to the alveolo-capillary exchanging membrane, defined by the flux of I-HSA from blood to edema fluid, were significantly differentiated from those with a lesser microvascular injury on the basis of higher mean heart rate (HR), temperature, cardiac index (CI), pulmonary artery pressures, right ventricular stroke work index (RVSWI), and a lower mean total white blood cell count (WBC), among others. Therefore, noncardiac pulmonary edema is characterized by a spectrum of permeability injury to the pulmonary microvasculature which seems to parallel other measurable indices of the severity of the systemic response to the illness.

Cell Membrane Permeability↗
PubMed1983

Variance-component estimation from human sibship data.

The large-sample relative efficiencies of the analysis-of-variance (ANOVA) estimators of variance components and the intraclass correlation coefficient rho are investigated for the unbalanced single classification in the context of family studies. The efficiency of an analysis based on the method of unweighted group means is also investigated. From a Monte Carlo study which generates the group sizes from typical family-size distributions it is found that the relative efficiency of the ANOVA estimators of the between-group variance component exceeds 95% for values of .2 less than or equal to rho less than or equal to .4, but can fall below 60% for values of rho that are very close to zero. For the estimation of the between-group variance component the method of unweighted means tends to be preferable to the ANOVA method only if rho greater than .5.

Analysis of Variance↗