Comparison of various electrophoretic characteristics of LDL particles and their relationship to the risk of ischemic heart disease.

BACKGROUND: Several cross-sectional studies and 3 prospective, nested, case-control studies have indicated that individuals with small, dense low density lipoprotein (LDL) particles are at increased risk for ischemic heart disease (IHD). However, whether LDL particle size is an independent risk factor for future IHD events remains controversial. The objective of the present study was to further analyze the cardiovascular risk associated with various electrophoretic characteristics of LDL particles in men. METHODS AND RESULTS: LDL particles were characterized by polyacrylamide gradient gel electrophoresis (PAGGE) in a cohort of 2034 men of the Quebec Cardiovascular Study. All men were initially free of IHD and were followed up for a period of 5 years, during which 108 first IHD events were recorded. Among all LDL characteristics investigated by PAGGE, including LDL peak particle size, the cholesterol concentration in LDL particles with a diameter smaller than 255 A showed the strongest association with the risk of IHD (relative risk=4.6 in men in the third vs first tertile of the distribution, P<0.001). Multivariate logistic and survival models indicated that the relationship between LDL cholesterol levels in particles with a diameter <255 A and IHD risk was independent of all nonlipid risk factors and of LDL cholesterol, high density lipoprotein cholesterol, triglyceride, and lipoprotein(a) levels. CONCLUSIONS: Results from this large, population-based, prospective study suggest that further characterization of LDL particles by PAGGE, in addition to the traditional lipid profile, may improve our ability to predict IHD events in men.

Age and duration of follow-up as modulators of the risk for ischemic heart disease associated with high plasma C-reactive protein levels in men.

BACKGROUND: Plasma C-reactive protein (CRP) levels recently have been identified as an emerging risk factor for ischemic heart disease (IHD). However, whether plasma CRP levels predict an increased risk for future IHD beyond traditional risk factors has yet to be evaluated in a large prospective, population-based study. METHODS: The association between elevated plasma CRP levels and the risk for future IHD was investigated in the prospective, population-based cohort of 2037 IHD-free middle-aged men from the Quebec Cardiovascular Study. During a 5-year follow-up, 105 first IHD events were recorded. Baseline plasma CRP levels were measured using a highly sensitive assay. RESULTS: High plasma CRP concentrations (equal to or above vs below the median level of 1.77 mg/L) were associated with a significant 1.8-fold increase in IHD risk (95% confidence interval [CI], 1.2-2.7). This association remained significant after adjustment for lipid risk factors but not when the simultaneous contribution of nonlipid traditional risk factors was taken into account. Multivariate analyses indicated that CRP level predicted short-term risk for IHD (events that occurred < or =2 years after the baseline evaluation), but not long-term risk (>2 years). Moreover, high plasma CRP levels predicted an increased risk for IHD, independent of any other confounder, in younger (< or =55 years) but not in older (>55 years) individuals. CONCLUSION: Plasma CRP levels may provide independent information on IHD risk only in younger middle-aged men and in the case of IHD events that may occur relatively soon after the baseline evaluation.

Effects of moderate amounts of emulsified dietary fat on postprandial lipemia and lipoproteins in normolipidemic adults.

Eight normolipidemic males ingested a meal containing either 42 g fat or 31 g fat in the form of emulsions (9.0 and 9.2 m2) and a fixed amount of retinyl palmitate. Fasting and postmeal blood samples were obtained for 7 h. Serum and chylomicron triglyceride responses were related to the amount of fat ingested and peaked after 2-3 h. The chylomicron retinyl palmitate response was lower (P < or = 0.05) with the 31-g fat supply. After the 42-g fat intake, but not after the 31-g fat intake, serum free cholesterol and phospholipids increased and esterified cholesterol decreased postprandially. Significantly different responses were observed after both meals for low-density-lipoprotein (LDL) free cholesterol, very-low-density-lipoprotein (VLDL) and LDL esterified cholesterol, and high-density-lipoprotein (HDL) phospholipids. These data show that ingesting 31 g instead of 42 g fat in a meal reduces postmeal lipoprotein variations and suggest that a threshold level of dietary fat should be overcome to promote significant postprandial changes in lipoprotein particles.

Postprandial appearance of dietary deuterated cholesterol in the chylomicron fraction and whole plasma in healthy subjects.

This study examined the appearance of dietary cholesterol in the chylomicron fraction (chylomicrons plus chylomicron remnants) and whole plasma in healthy normolipidemic subjects during a 0-7-h postprandial period. Six adult males were given two diet sequences in random order: a low-fiber diet (standard Western diet for 14 d) followed by a labeled low-fiber test meal or a fiber-supplemented diet (40 g oat bran/d for 14 d) followed by a labeled oat bran (40 g) test meal. The test meals provided 192.5 mg cholesterol, including 80.1 mg octadeuterated cholesterol. Fasting and hourly postmeal blood samples were obtained for 7 h. Isotopic cholesterol ratios [tracer:(tracer+native cholesterol)] were determined by gas chromatography-mass spectrometry. Chylomicron triacylglycerol and cholesterol concentrations peaked after 2-3 h and returned to baseline after 7 h. After the low-fiber test meal, the isotopic cholesterol ratio continuously increased until 7 h in the chylomicron fraction (4.2 +/- 1.2 x 10(-3)) and whole plasma (1.04 +/- 0.39 x 10(-3)). At 7 h postprandial, the maximum dietary cholesterol concentration in the chylomicron fraction and plasma cholesterol was 1 in 99 and 1 in 397 cholesterol molecules, respectively. No marked differences were obtained after the high-fiber sequence compared with the low-fiber one; there was a comparable isotopic cholesterol ratio and concentration in the chylomicron fraction and a slightly lower (-44%, P < 0.10) 0-7 h area under the curve whole-plasma deuterated cholesterol concentration. Thus, dietary cholesterol supplied as a single meal does not simultaneously appear in the chylomicron fraction postprandially with endogenous cholesterol and triacylglycerols and fiber feeding does not markedly alter this process in healthy normolipidemic humans.

Effects of oat bran, rice bran, wheat fiber, and wheat germ on postprandial lipemia in healthy adults.

Six normolipidemic males ingested on separate days a low-fiber test meal [2.8 g dietary fiber (TDF)] containing 70 g fat and 756 mg cholesterol, enriched or not with 10 g TDF as oat bran, rice bran, or wheat fiber or 4.2 g TDF as wheat germ. Fasting and postmeal blood samples were obtained for 7 h and chylomicrons were isolated. Adding fibers to the test meal induced no change in serum glucose or insulin responses. The serum triglyceride response was lower (P less than or equal to 0.05) in the presence of oat bran, wheat fiber, or wheat germ and chylomicron triglycerides were reduced with wheat fiber. All fiber sources reduced chylomicron cholesterol. Cholesterolemia decreased postprandially for 6 h and was further lowered in the presence of oat bran. Serum apolipoprotein (apo) A-1 and apo B concentrations were not affected. Thus, dietary fibers from cereals may reduce postprandial lipemia in humans to a variable extent.

Chronic oat bran intake alters postprandial lipemia and lipoproteins in healthy adults.

This study evaluates the possible interaction between chronic oat bran intake and the postmeal metabolic response. Six normolipidemic men consumed three different diets for 14 d, at the end of which they consumed a test meal. The diets were C (control), basal low-fiber diet (15.6 g fiber/d) and a low-fiber (2.8 g fiber) test meal; OB (oat bran), basal low-fiber diet and a 40-g oat bran-enriched test meal (12.8 g fiber); and OB-A (oat bran-adaptation), 14-d oat bran (40 g/d) supplemented diet (23.8 g fiber/d) and an oat bran test meal (12.8 g fiber). The diets were fed in a random order. Fasting and postmeal blood samples were obtained for 7 h and lipoproteins were isolated. Adding oat bran to the test meals markedly reduced the postmeal insulin rise (P < 0.05). Compared with the low-fiber control diet, the effects elicited postprandially by adding oat bran to a single meal were enhanced after 14 d of oat bran feeding, ie, increased plasma triglycerides, phospholipids, and free cholesterol; decreased plasma esterified cholesterol; increased chylomicron and small-sized triglyceride-rich lipoprotein triglycerides; increased LDL and HDL free cholesterol; and decreased HDL esterified cholesterol. Thus, chronic oat bran feeding alters the postmeal response in human subjects.

Pretransplant and posttransplant antibodies in human corneal transplantation.

The purpose of this study was to measure the association between antibody formation and endothelial corneal allograft reactions in 533 consecutive corneal graft recipients. The median follow-up time of these recipients was 732 days. Pretransplant panel-reactive antibodies were not found to be associated with endothelial corneal allograft reactions. Out of 533 recipients, 239 developed posttransplant antibodies during the course of this study. The formation of posttransplant antibodies was frequent in recipients with pretransplant antibodies and in HLA-A,-B-incompatible recipients. Posttransplant antibodies most often appeared within the first six months after transplantation whereas endothelial allograft reactions most often occurred later. Out of 65 recipients who developed PPRA and underwent an allograft reaction, 53 had a PPRA peak prior to, or at about the time of, the allograft reaction. Corneal allograft reaction events diagnosed during the second and third year after surgery were correlated with PPRA formation during the first year after grafting. The 36-month reaction-free survival rate of transplants was estimated at 72% in recipients with PPRA compared with 86% in recipients without PPRA (log rank P value = 0.002). Furthermore, posttransplant antibody formation altered the outcome of corneal allografts in both HLA-A and -B-compatible and -incompatible recipients. These findings suggest that posttransplant antibody development represents a high risk of endothelial corneal allograft reactions.

Outbreak of glutaraldehyde-induced proctocolitis.

BACKGROUND: An outbreak of hemorrhagic proctocolitis occurred after the introduction of 2% glutaraldehyde as a disinfectant for colonoscopes. An inadequate rinsing procedure was detected. Recent studies have pointed to glutaraldehyde as an irritant potentially capable of inducing colitis. This study aimed to measure retrospectively the occurrence of proctocolitis after colonoscopy in persons exposed to glutaraldehyde used as a disinfectant for colonoscopes, and to compare this rate with that in patients exposed to the previous cleaning procedure. METHODS: Colonoscopic procedures were randomly selected during the period when glutaraldehyde was used, as well as during the previous period, when a detergent was used. Patients were asked to respond to a questionnaire during a telephone interview, in search of symptoms compatible with proctocolitis after colonoscopy. RESULTS: Of the 400 colonoscopic procedures selected during each of the glutaraldehyde and the detergent periods, respectively 299 and 242 were evaluable. According to different nonexclusive definitions, we observed in the glutaraldehyde period higher frequencies of proctocolitis (at least five stools/day; 14/299 vs 3/242, p = 0.02), severe proctocolitis (> 10 stools/day; 10/299 vs 1/242, p = 0.04), and severe hemorrhagic proctocolitis (6/299 vs 0/242, p = 0.04). Younger age was associated with proctocolitis only during the glutaraldehyde period (p = 0.0008). No pathogen was demonstrated in the only two patients who had stool cultures. The median incubation after colonoscopy was 4 hours (range 0 to 24 hours) and the symptoms lasted 30 hours (range 6 to 216 hours). No patient had fever, and the illness resolved spontaneously in all cases. CONCLUSION: Inadequate rinsing of colonoscopes after immersion in glutaraldehyde may result in proctocolitis, presumably caused by direct action on the mucosa.

Prediction of preterm delivery by fetal fibronectin: a meta-analysis.

OBJECTIVE: To assess the cervicovaginal fetal fibronectin test to predict preterm delivery. DATA SOURCES: We searched MEDLINE, Current Contents, Index Medicus, and proceedings of meetings for studies published between 1991 and June 1997. METHODS OF STUDY SELECTION: Inclusion criteria were prospective cohort study; test performed between 20 and 36 weeks' gestation; fetal fibronectin measured by a previously described assay, with a cutoff level set at 50 ng/mL; test results not disclosed to women or physicians; and fewer than 20% of study participants excluded from the analysis. TABULATION, INTEGRATION, AND RESULTS: Twenty-nine relevant studies were stratified according to the prevalence of preterm delivery, the number of tests performed, and delivery before 34, 35, or 37 weeks. Sensitivities, specificities, and likelihood ratios were calculated in each study. The summary estimates of the likelihood ratio for tests yielding positive results or tests yielding negative results along with their 95% confidence intervals (CIs) were computed in each stratum according to a random-effects model. All summary likelihood ratios for a test yielding positive results indicated a significant association with preterm delivery. The strongest association was found between a single test with positive results and delivery before 37 weeks in a low-risk population (likelihood ratio 7.5; 95% CI 4.6, 12.3). This association also was found in high-risk women (likelihood ratio 3.5; 95% CI 2.6, 4.6). In high-risk women, a test yielding negative results was associated with a reduction in risk of preterm delivery (likelihood ratio 0.4; 95% CI 0.3, 0.5). CONCLUSION: Fetal fibronectin in cervicovaginal secretions is associated with preterm delivery in both high-risk and low-risk women.

Effect of factors unrelated to tissue matching on corneal transplant endothelial rejection.

We examined 348 consecutive adult recipients of a corneal transplant for clinical signs of an endothelial rejection episode in a single-center follow-up study. The variables studied included primary diagnosis, number of previous corneal transplants, previous transplant failures from rejection episodes, transplant size, recipient corneal vascularization, donor age, recipient age and sex, past blood transfusions, and number of pregnancies. Five important risk factors were identified: primary diagnosis of herpetic, interstitial, or traumatic keratitis; transplant size 8 mm and larger; more than one previous corneal transplant; recipients younger than 60 years of age; and the presence of recipient corneal vascularization. This information will serve eventually for analyzing the effect of donor recipient tissue matching on corneal transplant rejection.

Piecework, repetitive work and medicine use in the clothing industry.

This study was designed to examine the potential effects of severe time constraints on workers' health. Medicine use is considered to be an indicator of non-specific morbidity that is worthy of interest in industrial health research when it is possible to compare workers who share the same culture and socio-economic characteristics, but are submitted to different work conditions. In the clothing industry, our hypotheses were that (1) piecework paid operators would have a higher percentage of medicine users than the hourly paid and (2) operators who did repetitive work would have a higher percentage of medicine users than those who did non-repetitive work. Women selected into the study were between the ages of 45 and 70, natives of Canada, spoke French and lived in the metropolitan region of Montreal. The occupational data came from the files of The Ladies' Clothing Joint Commission. They encompass the 30-year period 1956-85. Data on socio-economic characteristics, smoking status and medicine use of the 800 respondents were obtained by questionnaires administered by specially trained nurses. Among currently employed women, the probability of using stomach medication was higher for pieceworkers than among women who received an hourly wage: OR = 2.57 (1.19-3.96). The probability was also higher for women who did repetitive work than for women who did non-repetitive work: OR = 2.43 (1.26-3.60).

Effects of pea and soybean fibre on postprandial lipaemia and lipoproteins in healthy adults.

To evaluate some possible mechanisms whereby total dietary fibre (TDF) may affect lipid metabolism in humans, six normolipidaemic males ingested on separate days a low-fibre test meal (2.8 g TDF) containing 70 g fat and 756 mg cholesterol, enriched with 10 g TDF in the form of either pea fibre or soybean fibre. Fasting and post-meal blood samples were obtained for 7 h and chylomicrons (CM) were isolated. Lipoproteins (VLDL+CM remnants, LDL, HDL) were isolated from the baseline samples and the samples of the 2-3 h triglyceride peaks. As compared to the postprandial response given by the control low-fibre test meal, adding fibre induced no change in serum glucose, insulin or Apo A1 and Apo B variations. The serum triglyceride response was not altered by adding fibres but the 2-3 h chylomicron triglyceride rise was increased (P < or = 0.05) by soybean fibre. VLDL+CM remnants, LDL and HDL triglyceride variations were unchanged with fibres. Cholesterolaemia decreased postprandially for 6 h, and was further lowered in the presence of pea fibre. This resulted from a marked decrease in serum esterified cholesterol. The chylomicron cholesterol and phospholipid rise was lowered in the presence of either fibre. The postprandial changes in the free cholesterol concentrations of the various lipoprotein classes were not altered by fibre whereas changes from baseline in esterified cholesterol concentrations were reduced by soybean fibre in LDL and amplified by soybean and pea fibres in HDL. The results obtained show that dietary fibre present in legumes may alter postprandial lipaemia and lipoproteins in humans to a variable extent. These effects could be related to some long-term metabolic effects.

Association between characteristics of locomotion and accomplishment of life habits in children with cerebral palsy.

BACKGROUND AND PURPOSE: "Handicap situation" is defined in the literature as "a disruption in the accomplishment of a person's life habits (activities of daily living and social roles)." The purpose of this study was to determine the strength of association between various types of locomotion and the accomplishment of life habits, which is an indicator of the occurrence of handicap situations in children with cerebral palsy. SUBJECTS: Ninety-eight children with cerebral palsy, aged 5 to 17.8 years (mean = 10.5, SD = 3.5), were recruited. METHODS: The Life Habits Assessment was used to evaluate handicap situations in activities of daily living and social roles. Types of locomotion, the Pediatric Functional Independence Measure (locomotion section), and 2 tests representing functional activities (walking speed and stair climbing) were used as characteristics of locomotion. RESULTS: Locomotion capabilities were associated with the accomplishment of activities of daily living and social roles. Performance in variables related to locomotion, number of associated problems, and type of cerebral palsy explained 17% to 74% of the total variance in accomplishment of life habits in children who walked without technical aids. CONCLUSION AND DISCUSSION: The results suggest that locomotion might influence the accomplishment of life habits. Other factors, however--such as environmental barriers--should also be examined to determine their impact on the occurrence of handicap situations.

[Anti-influenza vaccination in a family medicine department]. / Vaccination anti-influenza dans une unité de médecine familiale (1988-1992).

This study describes the anti-influenza vaccination coverage of persons aged 65 or over who presented at the family medicine unit (FMU) of the Saint-Sacrement Hospital (Quebec City), between January 1988 and December 1992. All individuals were classified according to their anti-influenza vaccination status for each vaccination period. In general, the proportion of vaccinated persons increased by 14.1% during the five-year vaccination period. The mean increase in the proportion of vaccinated persons is 22.6% for those seen at least once a year at the FMU and 52.6% for those who were vaccinated at the FMU the previous year. The study results indicate that regular medical examination and previous vaccination increase the likelihood of subsequent vaccination in persons aged 65 or over.

Factors affecting the ingestion of fluoride dentifrice by children.

Several factors affecting the amount of fluoride ingested during toothbrushing by 2- to 7-year-old children were investigated. The specific purpose of this study was to determine the contribution of age, the amount of dentifrice used, and rinsing after brushing to the variation in the ingestion of fluoride dentifrice. Four hundred and five children brushed their teeth in front of a portable sink. The tubes of dentifrice in gel (0.24% NaF) were weighed before and after use to determine the amount of toothpaste used. The fluoride content of the collected liquids was determined with a fluoride-ion-specific electrode. The amount of fluoride ingested was derived by determining the difference between the amounts used and recovered. The amount of dentifrice used, the age, and the rinsing habits, entered in a multiple regression model, explained up to 66 percent of the total variation in the amount of fluoride ingested. The amount of dentifrice used accounted by itself for 60 percent of the total variation. Therefore, these results indicate that the quantity of dentifrice used was the most important factor affecting the ingestion of fluoride through toothbrushing by young children.

[Relation between blood pressure and smoking in a population of Quebec workers]. / Relation entre la tension artérielle et le tabagisme dans une population de travailleurs québécois.

Relations between blood pressure and cigarette smoking were investigated on the basis of a health survey conducted in a population of 3034 mine workers from Quebec Province. Blood pressure was found to be lower among smokers than among non-smokers, the difference between these two groups being: systolic pressure 2.3 mmHg, diastolic pressure 3.0 mmHg. After adjustment for age and bodyweight this relation persisted but only as far as diastolic pressure was concerned. The prevalence of hypertension was 1.5 times higher in non-smokers than in smokers. On the other hand, the number of cigarette-smoking years and the number of cigarettes smoked per day seemed to have little effect on mean arterial pressure.

[Normal confidence interval for a summary measure]. / Intervalle de confiance normal pour une mesure pondérée.

This paper proposes an approach for calculating the normal confidence interval of a weighted summary measure which requires a particular continuous transformation for its variance estimation. By using the transformation properties and applying the delta method, the variance of transformed measure is easily expressed in terms of the transformed specific measure variances and the squared weights. The confidence limits of the summary measure are easily deduced by inverse transformation of those of transformed measure. The method is illustrated by applying it to some well known epidemiological measures. It seems appropriate for application in stratified analysis context where size allows normal approximation.

[Adjustment and standardization: 2 concepts]. / Adjustement et standardisation: deux concepts.

This paper aims at clarifying and distinguishing the notions of adjustment and standardization. These two notions are often ill understood and utilized. Adjustment is conceived as a process of summarizing a set of specific measures. Standardization is conceived as an adjustment to an identical system of weights of two or many sets of specific measures. In the presence of confounding factors, the practice of standardization is essential in order to get valid comparisons between groups. Examples of non adjusted measures, of adjusted but non standardized measures, finally of standardized measures are examined.

[Calculation of sample size for the detection of relative risk with a predetermined confidence level and power]. / Calcul des tailles d'échantillons pour la détection d'un risque relatif, avec un niveau de confiance et une puissance déterminés.

Herein, a method of calculation is proposed for determining the number of subjects required for risk ratio detection, the significance level (alpha) and the power (1 - beta) being fixed in advance. Risk ratios under consideration are rate ratios, proportion ratios and odds ratios. The method of calculation is based on the logarithmic transformation.

[Relationship between preoperative delay in hip fractures, postoperative complications and risk of death]. / Relation entre le délai pré-opératoire pour une fracture de hanche, les complications post-opératoires et le risque de décès.

The objective was to describe the relationship between preoperative delay, postoperative complications, and risk of death at 6 months. The population is constituted of 200 subjects aged 65 years or older who were living at home and treated for a hip fracture in any of three of Québec's hospitals between April, 1st, 1987 and March, 31, 1989. Chi-square or F-test, and linear and logistic regression were used to test the relationship between the variables. Preoperative delays varied from 2 to 403 h (median, 45 h). Variations between hospitals were particularly important; median delay at hospital 1 was 109 h, at hospital 2, 36 h, at hospital 3, 30.5 h. Only 5% of the variance of the delay was explained by the subjects' characteristics before the fracture. The relationships between delay and postoperative complications are not significant. However, the risk of death at 6 months increased with the length of operative delay; the observed increase tends to be linear (p = 0.03). These results suggest first, that surgery for hip fracture had to be consider as an urgency, second, that it could be done 36 hours or less after the arrival at hospital.