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Biomedical subjects

P Corey

Publications and source records attributed to P Corey.

At least 19 recordsLinked to original sources
PubMed1995

A workers' compensation claim population for occupational asthma. Comparison of subgroups.

STUDY OBJECTIVE: (1) To compare patients with claims submitted to the Ontario Workers' Compensation Board (WCB) for occupational asthma, in relation to the WCB decisions reached of occupational asthma (OA); aggravation of asthma from irritant exposures (AA); unrelated asthma; no asthma; and (2) to assess determinants of outcome of WCB accepted claims at permanent disability assessments. DESIGN: A retrospective review of 609 claims submitted to the WCB 1984 to 1988. RESULTS: The WCB decision reached was OA in 39% of claims, mostly attributed to isocyanates (57% of these). A further 39% were accepted for AA. Exposure to a known sensitizer occurred in 91% with OA and to an irritant in 67% with AA. Forty percent with AA were attributed to a spill or accidental exposure and 68% had preceding asthma. Those with AA were more likely to have clearing of symptoms by the time of their main assessment (43% vs 20% with OA) and were more likely to have remained in the same work (35% vs 20% with OA). Of 200 OA accepted claims reviewed at a mean of 1.9 years later, clearing of asthma occurred in 19% and milder asthma in 47%. Outcome was best with early diagnosis (p < 0.05), and milder impairment of pulmonary function at initial assessment (p < 0.05). CONCLUSIONS: Patients with asthma induced by a workplace sensitizer demonstrate some differences from those related to workplace irritants. Accurate categorization and early removal of those with OA offers the best prognosis.

Adult↗
PubMed1993

The apolipoprotein E gene and the serum low-density lipoprotein cholesterol response to dietary fiber.

Our goal was to determine whether differences in apolipoprotein E (apo E) influenced the response to dietary changes aimed at reducing serum cholesterol levels, especially increases in fiber. Apo E phenotype and genotype were determined in 43 men and 24 women who had previously taken part in parallel 2-week metabolic dietary studies involving either wheat bran or oat bran supplementation at a level of 6.8 g fiber/1,000 kcal. Fasting blood lipid measurements had been made at the beginning and end of the 2-week metabolic period. Reductions in low-density lipoprotein (LDL) cholesterol levels across both oat and wheat bran diets were significantly different depending on the E allele (P = .048). The LDL cholesterol level reduction for E2 carriers (0.60 +/- 0.14 mmol/L, n = 13) was greater than that for E3 homozygotes (0.21 +/- 0.07 mmol/L, n = 38; P = .014) and E4 carriers (0.28 +/- 0.12 mmol/L, n = 16; P = .09). Only the change in dietary fiber on the oat bran diet was related significantly to the decrease in LDL cholesterol levels (r = -.47, P = .007; n = 32). No such relationship was seen on the wheat bran diet (r = -.010, P = .59; n = 33). Carriers of the E2 allele appear to be more responsive than noncarriers to a dietary change involving increased fiber intake. The data also support a lipid-lowering advantage of oat bran over wheat bran. Current dietary recommendations to reduce serum lipid levels may vary in effectiveness depending on distribution of apo E alleles in the different populations studied.

Adult↗
PubMed1992

The effects of continuous exposure to 20-kHz sawtooth magnetic fields on the litters of CD-1 mice.

Mated CD-1 mice were exposed to 20-kHz sawtooth magnetic fields similar to those associated with video display terminals (VDT). Four groups of animals were continuously exposed from day 1 to day 18 of pregnancy to field strengths of 0, 3.6, 17, or 200 microT. There were no less than 185 mated dams in each exposure group. On day 18, the dams were sacrificed and assessed for weight gain and pregnancy. The litters were evaluated for numbers of implantations, fetal deaths and resorptions, gross external, visceral and skeletal malformations, and fetal weights. There were no less than 140 pregnant females in each group, and there were no significant differences between any of the exposure groups and the sham group (0 microT) for any of the end points. The results of this study do not support the hypothesis that the 20-kHz VLF magnetic fields associated with video display terminals are teratogenic in mammals.

Abnormalities, Radiation-Induced↗
PubMed1992

Metabolic advantages of spreading the nutrient load: effects of increased meal frequency in non-insulin-dependent diabetes.

The acute effect of increasing meal frequency as a model of slow absorption was studied for 1 d in 11 patients with non-insulin-dependent diabetes. On 1 d they took 13 snacks (the nibbling diet) and on another day the same diet was taken as three meals and one snack (the three-meal diet). The nibbling diet reduced mean blood glucose, serum insulin, and C peptide concentrations over the 9.5 h of observation and 24-h urinary C peptide output by 12.7 +/- 3.7% (mean +/- SE) (P = 0.0062), 20.1 +/- 5.8% (P = 0.0108), 9.2 +/- 2.6% (P = 0.0073), and 20.37 +/- 8.12% (P = 0.039), respectively, compared with the three-meal diet. Serum triglyceride concentrations were lower by 8.5 +/- 3.2% (P = 0.037). Despite lower insulin concentrations on the nibbling diet, the concentrations of free fatty acids, 3-hydroxybutyrate, and the insulin-sensitive branched-chain amino acids responded similarly on both treatments. Metabolic benefits seen with increased meal frequency may explain the success of similar agents that prolong absorption, including fiber and enzyme inhibitors.

Adult↗
PubMed1992

Reliability and validity of a fitness assessment for epidemiological studies.

A pilot study was conducted to investigate the applicability of the Canadian Aerobic Fitness Test (CAFT) for use in epidemiological studies. Thirty subjects ranging in age from 18 to 65 were evaluated for cardiorespiratory fitness on four separate visits. Protocols used included maximal treadmill testing, maximal step testing, and the CAFT. Results from these evaluations suggested that (a) habituation to the CAFT was negligible; (b) prediction of VO2max from the CAFT in fit subjects remains a problem and further equation development for this group may be necessary; (c) maximal step-test protocols do not result in unequivocal VO2max determinations and may lead to misclassification of fitness level; and (d) although the CAFT correlates highly to treadmill VO2max (r = 0.90), a relatively large standard error may result in as high as a 13% error in estimating VO2max and may lead to problems in classifying fitness in some populations (e.g., older unfit).

Adolescent↗
PubMed1991

Specific types of colonic fermentation may raise low-density-lipoprotein-cholesterol concentrations.

To assess the effects of increased colonic fermentation on serum lipids, eight healthy volunteers were placed on two identical 2-wk metabolic diets, one of which was supplemented with lactulose (18-25 g/d). Lactulose raised day-long concentrations of breath hydrogen and serum glutamine as indicators of increased colonic fermentation by 78 +/- 13% (P less than 0.001) and 24.7 +/- 9.5% (P less than 0.05), respectively). Unexpectedly, however, fasting serum total and low-density-lipoprotein cholesterol and apolipoprotein B concentrations were higher at 2 wk by 8.9 +/- 1.5% (P less than 0.001), 10.9 +/- 2.2% (P less than 0.005), and 18.9 +/- 5.9% (P less than 0.02), respectively, compared with the control diet. With lactulose, mean free fatty acid concentrations were reduced over the day by 19.5 +/- 5.9% (P less than 0.02), with no change in mean day-long blood glucose, serum insulin, or C-peptide concentrations. We conclude that certain rapidly fermented substrates may raise rather than lower serum lipids, possibly through increasing the amount of acetate absorbed from the colon.

Acetates↗
PubMed1991

Formaldehyde exposure and health status in households.

This report describes a case study concerned with acute and subacute health effects of formaldehyde in the indoor air, which is based on a large group of control houses and houses retroinsulated 4 to 5 years earlier with urea formaldehyde foam insulation (UFFI). Both groups underwent an environmental and health assessment on two occasions separated by an interval of 12 months, during which about one-half of the UFFI group performed remedial work on their houses. The results show that in the first survey of the study population, before remedial work, there was a moderate excess of many adverse health status indicators among the UFFI subset relative to the controls. This was associated with the presence of direct exposure-response relationships between formaldehyde levels in the UFFI houses and the prevalence of a number of symptoms. No comparable relationships were seen among the controls. At the second survey, performed following the removal of the UFFI, there was an appreciable reduction in the excess of most adverse health status indicators among the UFFI subjects. This improvement in health status among the UFFI removal subset was not associated with any significant diminution of formaldehyde exposures, although the previously observed exposure-response relationships had vanished. These observations imply that the findings obtained in the preremedial stage of the study cannot be explained by formaldehyde exposure alone.

Adult↗
PubMed1990

Prevalence and correlates of family dysfunction and poor adjustment to chronic illness in specialty clinics.

This study estimated the prevalence of poor adjustment and family dysfunction among three chronically ill clinic patient populations and assessed the biological, situational, social and psychological variables which most explained poor adjustment. Recently referred subjects were approached and 216 chronically ill subjects (from oncology, rheumatology and gastroenterology clinics) completed a Meaning of Illness Questionnaire, the McMaster Family Assessment Device, and the Psychosocial Adjustment to Illness Self-report Scale. In addition, information describing their biological, disease and socioeconomic status was obtained from the clinic record. Respondents were generally representative of other new referrals to the clinics (ineligible for the subsequent trial) in disease characteristics but uniformly came from a more advantaged socioeconomic situation and were better adjusted to illness. Subjects from the three clinics were comparable on meaning, family function and adjustment variables. The proportion of subjects with family dysfunction was 30% and with poor adjustment to illness was 36%, high by community standards. Nevertheless, healthy family functioning and high levels of positive adjustment to chronic illness prevailed and were remarkably similar across clinic settings. Severity or type of disease was not related to adjustment outcomes nor to the level of observed disability. Rather, as hypothesized, meaning given the illness, followed by family function, and disability variables combined to explain 57% of the variance in adjustment outcomes. An intervention designed to improve family function and the meaning given illness was judged suitable.

Adaptation, Psychological↗
PubMed1990

Individual correlates of health service utilization and the cost of poor adjustment to chronic illness.

It was conjectured that a small group of chronically ill in tertiary ambulatory clinics consume a large amount of health resources and that, from the perspective of the patient, psychosocial rather than disease variables would most explain their health service utilization and subsequent cost. New referrals with a chronic illness (N = 215) to one of three clinics (oncology, rheumatology, and gastroenterology) consented to participate in a subsequent trial of a psychosocial intervention designed to promote their adjustment to illness and, conceivably, to reduce their health service utilization. At baseline an inventory to describe the disease, treatment, functional capacity, prognosis, and socioeconomic situation of consenting subjects was completed. In addition, subjects completed the Psychosocial Adjustment to Illness Inventory (PAIS-SR), the Family Assessment Device (FAD), the Meaning of Illness Questionnaire (MIQ), and a Health Service Utilization Inventory designed to assess direct and indirect costs of health resources. These data were entered into a concurrent analytic survey design. Participating subjects represented a more socioeconomically advantaged and better-adjusted group of chronically ill patients compared with others referred to the tertiary clinics. They were representative of all new referrals in their use of the majority of health services. However, once hospitalized, participating subjects stayed longer and used specialists less. There was no important relationship between disease severity or prognosis and any type of service utilization, including hospitalization. Because the strongest correlate of all types of health services consumed was psychosocial adjustment to illness (r = 0.28 to 0.33), patients were partitioned into one of three categories of adjustment to illness: good, fair, and poor. The total annual cost per patient was $23,883, if poorly adjusted, compared with $9,791 if well adjusted. If cash transfers (benefits paid by different types of insurance) are added, the average 1987 annual cost per poorly adjusted subject was $31,291 per patient, compared with $13,771 for a patient well adjusted to the illness. There was a statistically significant and economically important linear gradient in 1987 treatment costs per category of adjustment. The possible economic implications for psychosocial intervention are highlighted.

Adaptation, Psychological↗
PubMed1989

The effect of domestic factors on respiratory symptoms and FEV1.

This study was conducted to determine whether indoor air pollution factors affected respiratory function and symptoms in 1357 non-smoking Caucasian children. Interviews were conducted to determine: exposure to pets and to gases, vapours and dusts from hobbies; the use of gas stoves; fireplaces, air conditioners and humidifiers; type of heating systems; and the number of residents, and the number of smokers in the home. The forced expiratory volume in one second (FEV1) was obtained from maximum expiratory flow volume curves, and symptoms from the application of a standardized questionnaire. Indoor pets and the use of fireplaces and humidifiers had no consistent relationships with FEV1 when considered individually or in combination with the other factors. Hobbies, the use of gas stoves, the absence of air conditioning, the use of hot water heating, crowded homes, and the presence of smokers in the home all had negative relationships with FEV1. The largest effect on lung function was observed in children from homes with hot water heating systems, whereas the smallest effect was observed in children with smokers in the home. Children who lived in homes with hot water heating systems with no air conditioning had mean FEV1 of up to 0.4 litres lower than did their counterparts who lived in homes with forced air heating and air conditioning. Pets, heating systems, cooking fuel, crowding and passive smoking showed no consistent effects on the reporting of any of the symptoms. Girls who were exposed to the emissions from indoor hobbies reported more phlegm, wheeze and dyspnoea.

Adolescent↗
PubMed1989

Discovery and synthesis of rioprostil.

Between 1972 and 1979 a research team at Miles Laboratories produced 1200 prostaglandin analogues as potential pharmaceuticals. Most of these analogues were produced using the Sih synthesis. They were screened in several animal models and a few were found to inhibit gastric acid secretion in the rat. The best compound (TR-4698, rioprostil) is being pursued as an anti-ulcer and cytoprotective agent. An improved synthesis of this compound involves the use of n-butyllithium and copper (I) cyanide in a one-pot conjugate addition of a vinyl tin intermediate with a chiral alkylated cyclopentenone. Multihundred gram lots of rioprostil are produced with only one chromatography, that of the final substance, needed.

Animals↗
PubMed1989

Health status and sulfur dioxide exposure of nickel smelter workers and civic laborers.

We examined a group of 143 nickel smelter workers who processed a high sulfide ore, and compared their health status with that of 117 civic laborers. All subjects were studied over the first four days of a week of work, administering a health questionnaire on day 1, measuring their pulmonary function on the morning of day 1 and day 4, and monitoring their personal exposure to SO2 and particulates over the same period. The smelter workers were exposed to an average of 0.374 mg/m3 of respirable particulates, a threefold higher level than the controls, and to 0.67 ppm of sulfur dioxide, a 40-fold greater amount than the controls, but were found to show no excess of chronic respiratory symptoms and did not differ from the controls either in their baseline pulmonary function or in their change from the morning of day 1 to day 4. However, there were several indicators of a healthy worker effect in the smelter worker group.

Air Pollutants, Occupational↗
PubMed1989

The evaluation of intranasal topical beclomethasone spray in the treatment of children with non-purulent rhinitis using rhinometric, cytologic and symptomatologic assessment.

The diagnosis and treatment of non-purulent rhinitis in the pediatric population poses a challenge to the clinician. In this randomized double blind study, the authors conclude that rhinometry is more effective than cytologic or symptomologic assessment in children with non-purulent rhinitis treated with either intranasal beclomethasone or placebo spray. Intranasal beclomethasone spray produced significant reductions in nasal airflow resistance values compared to the placebo-treated group.

Administration, Intranasal↗
PubMed1988

Does suggestibility modify acute reactions to passive cigarette smoke exposure?

The influence of suggestibility on responses to passive cigarette smoke exposure was tested in a group of 24 healthy adult nonasthmatic nonsmokers and 16 asthmatic nonsmokers. Sixty-five-min exposures to air and to moderate (17 ppm carbon monoxide) and heavy (31 ppm carbon monoxide) concentrations of machine-produced cigarette smoke were carried out according to a design that permitted all six permutations of the three treatments to be equally represented. Nonasthmatic subjects exercised intermittently at an intensity inducing a respiratory ventilation of 43.6 liters/min, while asthmatic individuals were at rest, in a 14.6-m3 chamber; all viewed a bank of burning cigarettes during each exposure. Significant dose-response relationships were observed for reported symptoms, deterioration of pulmonary function, increase in nasal airflow resistance, and increase of carboxyhemoglobin levels. These findings could reflect either a pure physiological response, or an interaction between physiological and psychological responses. For asthmatics, correlations between pulmonary function responses and baseline measures of suggestibility showed 5/45 (11%) significant correlations (P less than 0.05) for both the ratio of saline diluent/air FEV1 during methacholine inhalation challenge and an index derived from the Minnesota Multiphasic Personality Inventory (MMPI), while no significant correlations were shown with the James "locus of control" test. Nonasthmatics showed 4/45 (9%) significant correlations for both the James test and the MMPI index, and 1/45 (2%) for the ratio of saline diluent/air FEV1. It is concluded that while suggestibility may augment physiological responses to passive smoking, any effect is relatively weak.

Adult↗
PubMed1988

Comparison of health of occupants and characteristics of houses among control homes and homes insulated with urea formaldehyde foam. I. Methodology.

The methodology of a study in which a comparison is made of the health and house characteristics of the occupants of 231 control homes and 571 houses containing urea formaldehyde foam insulation (UFFI) is described. All homes and occupants were examined on two occasions separated by an interval of 12 months, during which two-thirds of the UFFI houses performed remedial work. The occupants were examined using a health questionnaire and a series of objective tests including pulmonary function, nasal airway resistance, sense of smell, nasal surface cytology, and patch tests. The houses were assessed using a questionnaire and measurements of indoor formaldehyde and carbon dioxide levels. No obvious bias has been identified in this survey with respect to the representativeness of the population studied, the classification of the UFFI and control groups, and the input from both the respondents and observers. The symptom responses made by individuals within the same households were not correlated. Quality control assessment of the objective health tests and formaldehyde sampling and assays demonstrated that these procedures remained stable over the two phases of the study, with the exception of the expected decrease in the pulmonary flow rates over 1 year and a small unexpected increase in the forced vital capacity and the forced expiratory volume in 1 s.

Airway Resistance↗
PubMed1988

Comparison of health of occupants and characteristics of houses among control homes and homes insulated with urea formaldehyde foam. II. Initial health and house variables and exposure-response relationships.

A health survey was conducted on 1726 occupants of urea formaldehyde foam insulated (UFFI) houses and 720 residents of control homes. The occupants of the UFFI houses showed a modest excess of many symptoms relative to the controls. This excess of complaints was contributed mainly by the residents of households which were intending to have their UFFI removed and by onsets which followed the installation of UFFI. There were no associated abnormalities in nasal airway resistance, sense of smell, pulmonary function, or patch tests for allergy to formaldehyde. However, the UFFI subjects intending to have their UFFI removed demonstrated a small increase in nasal epithelial squamous metaplasia. The indoor formaldehyde levels of the UFFI houses were about 20% higher than in the controls, while the carbon dioxide levels were similar in both groups. The UFFI subjects showed positive relationships between level of formaldehyde exposure and the presence of a number of symptoms, which were largely dependent on a small group of formaldehyde values that were in excess of 0.12 ppm. A number of the exposure-response relationships were enhanced by UFFI. These results suggested that some adverse health effects of UFFI were explained by formaldehyde alone while others were related to the combined effects of formaldehyde and an additional UFFI-related factor(s) which was not identified.

Carbon Dioxide↗
PubMed1988

Comparison of health of occupants and characteristics of houses among control homes and homes insulated with urea formaldehyde foam. III. Health and house variables following remedial work.

This report describes the second survey of a group of 762 control and urea formaldehyde foam insulated (UFFI) houses performed following an interval of 1 year, after about two-thirds of the UFFI households either had their UFFI removed or performed other UFFI-related remedial work. The UFFI subjects who lived in remedial houses showed a decline in indicators of impaired health status, to roughly equalize with those whose houses were not altered; they continued to show a small excess of adverse health indicators relative to the controls, but at a somewhat lower level than seen in the first survey. This improvement was not associated with changes in indoor levels of formaldehyde. Weak exposure-response relationships were observed between formaldehyde and upper and lower respiratory symptoms, but mainly in the combined UFFI and control populations; these are interpreted as representing the contribution of background levels of formaldehyde to the prevalence of respiratory complaints in the general population. The principal findings of this study were primarily based on subjective variables, but most could be directly validated by objective measurements in the UFFI and control subjects. The support for a causal relationship between impaired health and living in a UFFI house is considered to be moderately strong. However the demonstrated adverse effects are generally minor in nature.

Construction Materials↗