Biomedical subjects

P N Corey

Publications and source records attributed to P N Corey.

At least 19 recordsLinked to original sources

PubMed1992

An efficacy trial of a mammalian cell-derived recombinant DNA hepatitis B vaccine in infants born to mothers positive for HBsAg, in Shanghai, China.

We conducted a randomized, double-blind clinical trial of an experimental mammalian cell-derived DNA hepatitis B vaccine (Betagen, Connaught Laboratories Ltd, Toronto, Canada) to determine its efficacy in infants born to mothers who were carriers of hepatitis B surface antigen (HBsAg). Four groups of 55 infants received injections as follows: (1) a licensed plasma-derived vaccine (Lanzhou, Lanzhou Institute for Biological Products, Lanzhou, People's Republic of China), 20 micrograms; (2) Betagen, 20 micrograms; (3) Betagen, 20 micrograms+hepatitis B immune globulin (HBIG); and (4) Betagen, 10 micrograms+HBIG. Vaccine injections were given at birth and at 1 and 6 months and HBIG was given at birth. The vaccines were compared to a historical placebo control group. The efficacy of Betagen alone was 82.6% compared to 51.0% for the Lanzhou. Efficacy of Betagen increased with the concomitant use of HBIG. No infants who were HBsAg negative at birth and/or were born to hepatitis B e antigen (HBeAg) negative mothers became carriers. The rate of HBsAg in infants receiving Betagen alone, and born to mothers who were HBeAg positive, decreased from 60% at birth to 20% by the ninth month, compared to 62.5% and 50% (respectively) for Lanzhou. The percentage of infants with protective levels of antiHBs was significantly higher for Betagen alone than for Lanzhou, but the geometric mean titre of antiHBs for responders was not significantly different. We have shown that Betagen alone is highly efficacious in preventing the development of hepatitis B in infants born to mothers who are carriers of HBsAg and is also highly effective in reducing the carriage of HBsAg in infants who are HBsAg positive at birth and/or born to HBeAg positive mothers.

Carrier State↗

PubMed1992

Selection of a maximal test protocol to validate the Canadian Aerobic Fitness Test.

The purpose of this study was to select a maximal aerobic power test protocol with which to validate a submaximal step test prediction equation. Subjects (N = 129), males and females 15 to 69 years of age, performed one maximal step test and one maximal treadmill test. The maximal treadmill protocol yielded higher peak VO2, ventilation, heart rate, and RER values. An age-predicted maximum heart rate was achieved by 35% of subjects on the step test and 55% on the treadmill. An RER of 1.15 was attained by 22% of the subjects on the step test and 53% on the treadmill. Regression analysis indicated that the submaximal test was more predictive of VO2max when the maximum was attained using the treadmill rather than the maximal step protocol. Peak VO2 values obtained from subjects tested on the treadmill will be used to develop a new prediction equation for the Canadian Aerobic Fitness Test.

Adolescent↗

PubMed1990

Effect of exposure of miners to aluminium powder.

'McIntyre Powder' (finely ground aluminium and aluminium oxide) was used as a prophylactic agent against silicotic lung disease between 1944 and 1979 in mines in northern Ontario. To find out whether the practice produced neurotoxic effects a morbidity prevalence study was conducted between 1988 and 1989. There were no significant differences between exposed and non-exposed miners in reported diagnoses of neurological disorder; however, exposed miners performed less well than did unexposed workers on cognitive state examinations; also, the proportion of men with scores in the impaired range was greater in the exposed than non-exposed group. Likelihood of scores in the impaired range increased with duration of exposure. The findings are consistent with putative neurotoxicity of chronic aluminium exposure.

Aluminum↗

PubMed1990

Adjusting for clustering in survey research.

The current widespread application of cluster sampling in survey design presents concerns to the researcher regarding the chosen unit of study. The statistical power of a study could be spuriously increased or decreased, sample size could be altered dramatically, and the uniqueness of the individual unit under study (e.g., a patient) could be lost and substituted by average values of characteristics depending on which unit of study is selected. The 1985 National Ambulatory Medical Care Survey of the U.S. National Center for Health Statistics was used to illustrate research methodologies that would deflate spuriously high results due to clustered sampling. Using the individual patient as the study unit, correction factors ranging from 1.99 to 35.40 were calculated in order to deflate exaggerated t-tests, chi-square, and F values of predictor variables. The effect of clustering was more marked on (1) continuous rather than binary outcome variables, as the former provide a richer environment to form clusters; and (2) on outcome variables relating to the practice-related or personal style of physicians. Using the physician (who represented a cluster of patients) as the unit of study, it was realized that correction factors were relevant to physician-specific predictors but not patient-specific predictors. Using design effect correction factors developed from a simple univariate analysis of variance, pharmacoepidemiologists can analyze accurately the currently available large survey databases of clustered samples.

Cluster Analysis↗

PubMed1990

A randomized double-blind clinical trial of a mammalian cell-derived recombinant DNA hepatitis B vaccine compared with a plasma-derived vaccine.

Eight hundred volunteers from heath care and emergency fields participated in a randomized double-blind clinical trial of a new experimental mammalian cell-derived recombinant DNA hepatitis B vaccine (Betagen) compared with a licensed plasma-derived vaccine (Heptavax-B). Vaccine injections (20 micrograms) were administered intramuscularly at 0, 1, and 6 months, and sera were tested at 0, 1, 2, 3, 6, 7, and 12 months for hepatitis B surface antigen, antibody to hepatitis B surface antigen, and antibody to hepatitis B core antigen. Data from 745 vaccinees (93.1%), analyzed at the 7th month of follow-up, showed no significant difference in the seroconversion rates for Betagen (94.4%) vs Heptavax-B (97.3%), but the geometric mean titer of antibody was significantly higher for Heptavax-B (11 833 mIU/L) than for Betagen (4628 mIU/mL). The antibody response of Betagen was significantly and independently related to age and sex, while that of Heptavax-B was related to age only. Reported side effects from both vaccines were minor and mild, with approximately one fourth of all vaccinees reporting at least one side effect. Vaccinees, who had a protective level of antibody at the 7th month, were tested for antibodies at the 12th month. Of those in the Betagen-vaccinated group and those in the Heptavax-B-vaccinated group, 99.0% and 100%, respectively, were still protected. There was a proportionately larger decline in the geometric mean titers of antibody to hepatitis B surface antigen for Heptavax-B than for Betagen.

Adult↗

PubMed1989

Conceptual and methodological issues regarding the epidemiology of iron deficiency and their implications for studies of the functional consequences of iron deficiency.

This paper reviews the measures of iron status (hemoglobin, hematocrit, mean corpuscular hemoglobin concentration, mean cell volume, free erythrocyte protoporphyrin, serum iron, transferrin saturation, and serum ferritin) that are potentially available for inclusion in field studies of the relationship between iron and mental performance. The characteristics of these measures (sensitivity to iron status, specificity to iron, and diurnal and day-to-day variability) are reviewed and the implications of choice of variable for the design, analysis, and interpretation of studies are discussed. Brief consideration is given to the question of confounding variables and to sources of both false-positive and false-negative conclusions. The explicit message of the paper is that there is no perfect choice of measure of iron status but, given explicit definition of the research question, there are preferred choices that can most effectively combine the choice of variable and the design of the study.

Adult↗

PubMed1988

Six-month double-blind, controlled trial of high dose, concentrated beclomethasone dipropionate in the treatment of severe chronic asthma.

A six-month double-blind controlled trial compared a 2,000 microgram per day dose of beclomethasone dipropionate aerosol (BDP), with current upper level doses of 800 micrograms per day of the standard BDP, in asthmatics requiring oral corticosteroids in addition to BDP and bronchodilators. Both groups showed a significant reduction in their oral steroid requirements during the study, with a 34 percent reduction in the lower dose group and a 57 percent reduction in the high dose BDP group while maintaining good symptomatic control of asthma; there was an associated improvement in baseline serum cortisol levels. Over the same period, the pulmonary function of the lower dose group showed significant worsening relative to that of the group receiving the high dose BDP which improved. There was no increase in dysphonia or oropharyngeal candidiasis among those using the concentrated BDP. We conclude that high dose concentrated BDP appears to be a safe medication in long-term steroid-dependent asthma, and is effective in reducing dependence on the use of oral corticosteroid with associated improvement both in pulmonary and adrenal function.

Administration, Inhalation↗

PubMed1987

Safety and efficacy of long-term treatment with inhaled beclomethasone dipropionate in steroid-dependent asthma.

An open long-term trial of inhaled beclomethasone dipropionate was carried out in 32 asthmatic patients chronically dependent on systemic corticosteroids. Our objectives were to study the efficacy and safety of beclomethasone and to determine the proportion of patients in whom systemic steroids could be replaced by the new drug. All subjects had a clear history and physical findings of asthma as well as significant improvement in respiratory function after inhalation of salbutamol. Patients were followed for 4 to 8 years. Compared with a baseline period, patients receiving beclomethasone had reduced symptoms and needed less bronchodilator therapy, but their pulmonary function was unchanged. Bronchial biopsy specimens from seven patients who had been taking beclomethasone for as long as 8 years did not differ histologically from specimens from five asthmatic patients who had never taken the drug. Nine patients were able to stop taking systemic corticosteroids within 9 months, eight required them occasionally, and in eight the requirement was substantially reduced; the requirement did not change appreciably in the remaining seven. Inhaled beclomethasone is a safe and effective drug for chronic administration to asthmatic patients, and in 78% of our subjects the need for systemic steroids was substantially reduced or eliminated.

Administration, Inhalation↗

PubMed1987

A method for estimating "persons" versus "cases" from hospital morbidity data in the absence of unique personal identifiers.

The authors present a method for estimating the number of persons (as opposed to the number of admissions) admitted to hospital for a defined time period for specific diagnoses when unique personal identifiers are not available. A simple computer algorithm (algorithm 1), employing a family-based scrambled health insurance number in conjunction with diagnosis, sex, and age was used to estimate the rates of readmission to hospital specific diagnoses. A proportion of the hospital morbidity records used in the study did not contain a health insurance number; therefore, estimated readmission ratios for specific diagnoses, calculated from admissions with health insurance numbers, were applied to all admissions for those diagnoses to obtain the estimates of total persons admitted to hospital in the given time period. The validity of the methodology was tested for selected diagnoses for a specific year by 1) comparing estimates of persons obtained by applying algorithm 1 with manual counts of persons obtained through examination of printed lists of all Ontario admissions to hospital for the specific diagnoses, and 2) comparing actual counts of persons admitted to a specific hospital with computer estimates of persons admitted to that hospital. The conclusions drawn were that the method, using algorithm 1, is a valid one for obtaining estimates of the number of persons admitted to hospital in a given year with a specific diagnosis and that the information derived is potentially useful for conducting epidemiologic studies. Readmission ratios were also estimated through the use of a second algorithm (algorithm 2) which was not dependent on a scrambled health insurance number. Sensitivity and specificity of these ratios were found to be low when compared with ratios estimated by algorithm 1.

Algorithms↗

PubMed1985

Alcohol consumption and blood pressure: analysis of data from the Canada Health Survey.

Recent epidemiologic studies report a significant association between alcohol consumption and elevations in both systolic (SBP) and diastolic (DBP) blood pressures. To test this hypothesis, we conducted a multivariate analysis of physical examination and other data on 721 men and 697 women aged 20 or more collected during the Canada Health Survey in 1978-1979. SBP and DBP were considered as separate dependent variables in multiple regression models with the following independent variables: age, alcohol consumption (measured as a 7-day recall history and as an average frequency of consumption), serum cholesterol, plasma glucose, physical activity, Quetelet index, parental history of hypertension, cigarette consumption, income, education, and exogenous hormonal use in women. In both weighted and unweighted multiple regression analyses, we could not demonstrate for either sex, a significant association between alcohol consumption (as recorded and following quadratic and logarithmic transformations) and either SBP or DBP. For both sexes, only age and Quetelet index were highly significantly (P less than 0.0001) and consistently associated with both SBP and DBP. No other independent variables were consistently associated, for either sex, with SBP and DBP. Further, the dose-response patterns noted by other investigators suggesting either a positive and linear relationship or a curvilinear relationship were not found in either our univariate or multivariate analyses. Rather, the alcohol-blood pressure curves showed no consistent patterns of any kind in either sex. These findings do not support recent claims that alcohol consumption is a determinant of elevations in either SBP or DBP.

Adult↗

PubMed1985

Results of a controlled drug trial in membranoproliferative glomerulonephritis.

A prospective randomized drug trial was carried out on 59 patients with confirmed membranoproliferative glomerulonephritis (MPGN). The treatment group (27 patients) received cyclophosphamide, coumadin, and dipyridamole for 18 months, and the control group (32 patients) received no specific therapy. Complications of the renal disease such as hypertension and fluid retention were treated similarly in both groups. Entrance criteria included confirmed renal pathology demonstrating either types I or II MPGN, a corrected creatinine clearance (CCr) of less than 80 ml/min/1.73 m2, and/or proteinuria greater than 2 g/day. Actuarial survival was not different between the treatment and the control groups in either MPGN type and was 85% in type I and 90% in type II at 2 years. The change in renal function, as measured by both the slope of CCr and the plasma creatinine reciprocal (1/Cr) at 6, 12, and 18 months was not significantly different between treatment and control groups in either types I or II when tested by both parametric and nonparametric analysis. The age, sex, and initial level of CCr did not influence the rate of decline. Control and treatment group proteinuria was not different at any time point in either types I or II MPGN. The small numbers of type II MPGN cases do not give sufficient power to allow conclusions regarding this therapy in type II. We can conclude that this treatment is ineffective in altering the natural history of type I MPGN.

Adolescent↗

PubMed1979

Survey of the clinical use of pressurized aerosol inhalers.

Questions as to the use of pressurized aerosol inhalers were asked of 130 persons presenting for routine pulmonary function studies who had used such a device in the previous year. After spirometry was conducted the subjects used the inhaler; they were unaware that their technique of use was being observed. Only 10.8% performed correctly all 11 maneuvers suggested for the proper use of the inhalers, and 24.7% failed to perform more than 5 satisfactorily. There were significant differences in performance according to referral diagnosis (chronic obstructive lung disease v. asthma) and regularity of use of inhalers.

Adolescent↗

PubMed1979

Management of intractable ventricular tachyarrhythmias after myocardial infarction.

Twenty-five patients with recent or old myocardial infarction were studied because they had life-threatening ventricular arrhythmias that required repeated cardioversions and were intractable to medical management. All patients had had a large anterior infarction a mean of 4.6 weeks before the emergence of the arrhythmias and all had severe left ventricular dysfunction. Cardiac catheterization or autopsy revealed a left ventricular aneurysm in 18 of 18 patients and obstruction of the left anterior descending coronary artery in 20 of 20 patients. Of 16 patients treated surgically with aneurysm resection or coronary bypass grafting, or both, 10 (62 percent) were alive after 3 to 39 (mean 26) months of follow-up. The perioperative mortality rate was 31 percent and only one patient died during the postoperative follow-up period 4 months after discharge from the hospital. By contrast, all nine medically treated patients died either in the hospital (four patients) or suddenly within 2 months of discharge (five patients). Ventricular fibrillation was documented as the cause of death in five of these patients. Surgical intervention was found to improve significantly the survival of these patients (P less than 0.02). The perioperative mortality rate was lower when at least 4 weeks had elapsed from acute infarction to surgery (10 versus 67 percent) and when the procedure included coronary bypass grafting (13 versus 50 percent), although these differences were not statistically significant (P greater than 0.05).

Adult↗

PubMed1979

Racial differences in lung function: search for proportional relationships.

A comparison of lung function in Caucasian and East Indian woodworkers revealed marked differences in FEV, FVC, AND MMF in relation to predicted age- and height-specific values of these variables reported in the literature. These findings were not attributable to differences in smoking habits, frequency of respiratory disease, or employment characteristics. Rather, they suggested that the standard values employed were inappropriate for East Indians. An attempt was made to confirm previously reported suggestions of consistent proportional differences in lung function between racial groups which would permit the calculation of a single correction factor. Evidence of a consistent proportional relationship was found for FEV over a wide range of heights and for FVC over a limited range of heights. However, no such relationship was found for MMF.

Adolescent↗

PubMed1979