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Biomedical subjects

L Braeckman

Publications and source records attributed to L Braeckman.

15 recordsLinked to original sources
PubMed2003

Differential contribution of testosterone and estradiol in the determination of cholesterol and lipoprotein profile in healthy middle-aged men.

The role of endogenous sex steroids in the association between male gender and cardiovascular risk remains unclear. We performed a cross-sectional analysis of the role of endogenous testosterone (T) and estradiol (E2), as well as their respective biologically active fractions, in the determination of lipids and lipoproteins in an occupation-based cohort of 715 healthy middle-aged men. Serum T, sex hormone binding globulin (SHBG) and E(2) were measured by immunoassays; free T (FT) and free E2 (FE2) were calculated using a validated equation. Serum total cholesterol (Chol), HDL-cholesterol (HDL-Chol), apolipoproteins A1 (ApoA1), B (ApoB), E (ApoE), ApoE phenotype, lipoprotein a (Lpa), fibrinogen, C-reactive protein (CRP), systolic (SBP) and diastolic blood pressure (DBP) were assessed. Serum levels of T and FT, correlated positively with HDL-Chol and ApoA1 with Spearman correlation coefficients, partialised for age and body mass index (BMI), ranging between 0.14 and 0.17 (P<0.001); FT was associated with total Chol and ApoB levels (r=0.12 for both T and FT; P<0.01). After adjustment for age and BMI, both serum E2 and FE2 levels correlated significantly with ApoE (r=0.25 and r=0.26 for E2 and FE2, respectively; P<0.001). Free and total E2 were associated with both SBP and DBP with correlation coefficients partialised for age and BMI ranging between 0.11 and 0.13 (P<0.01). No correlation was found between any of the studied sex steroids, fibrinogen, Lpa or CRP. In multiple linear regression analyses, T was the most important independent hormonal determinant of HDL-Chol levels, when E2, SHBG and exogenous factors were considered in the model (P<0.01), whereas E2 contributed mostly in the determination of ApoE levels (P<0.001) and SBP (P<0.01). When FT and FE2 were considered in multivariate analyses as independent hormonal variables, FT was the most significant predictor of HDL-Chol (P<0.01) and ApoB (P<0.01) concentrations. Moreover, in the same multivariate model, ApoE (P<0.001) concentration as well as SBP (P<0.001) was most affected by FE2 levels in comparison with FT. In conclusion, our findings do suggest a differential role of T and E2 in the determination of traditional cardiovascular risk factors in healthy middle-aged men. In the determination of both HDL-Chol and ApoB levels endogenous (F)T may be involved, whereas (F)E2 may contribute to the determination of ApoE levels in this study group of 715 healthy middle-aged men. Regarding the observational design of the study, the physiological relationship of the observed associations between sex steroids and cardiovascular risk factors remains to be unravelled.

Adult↗
PubMed2001

The cross-sectional study of the health effects of occupational exposure to carbon disulfide in a Chinese viscose plant.

This article presents results of carbon disulfide exposure assessment in a Chinese viscose rayon factory and represents the cross-sectional study beginning phase of the occupational epidemiological project. The authors measured external exposure levels to carbon disulfide at a Chinese viscose rayon factory and monitored results as internal exposure indexes by testing urine samples of workers exposed to carbon disulfide levels. The rate at which carbon disulfide is metabolized by exposed subjects was demonstrated by 2-thio-thiazolidine-4-carboxylic acid (TTCA) concentrations in urine of exposed subjects, which was studied to determine best time points for internal exposure sampling. Carbon disulfide concentrations in the air of the workplace were analyzed with gas chromatography with flame photometric detector (GC-FPD); presence of TTCA in urine samples of subjects was determined using a modified high-performance liquid chromatography method. Kinetics of TTCA excretion was studied by analysis at different time points during and after exposure of workers to carbon disulfide. A total of 155 personal samples were obtained. Carbon disulfide concentration at staple viscose hall was found to be 13.72 +/- 1.12 mg/m3 in terms of geometric mean and geometric standard deviation. Carbon disulfide concentration at filament spinning hall was found to be 20.05 +/- 1.33 mg/m3. TTCA values of subjects at staple spinning hall were 1.18 +/- 0.43 and 1.07 +/- 0.38 mg/g creatinine for subjects working at filament spinning hall. The best time for TTCA sampling is at the end of the exposure-working shift.

Adult↗
PubMed2001

Carbon disulfide exposure assessment in a Chinese viscose filament plant.

UNLABELLED: Carbon disulfide is a well-known occupational hazard in the viscose industry, and studies have shown considerable health effects when workers are exposed to high concentrations of this reagent. At exposure levels below the TLV-TWA(31 mg/m3), findings remain contradictory, probably due to deficient exposure data. The present study tries to identify the occupational hazards and thoroughly assess the exposure levels in a Chinese viscose rayon plant. METHODS: An industrial hygienic field survey and a sampling campaign were carried out, including multi-gas monitoring, on-line measurements, and stationary assessment in the spinning hall as well as personal exposure sampling for spinners (by charcoal tube absorbing and GC-FPD analysis). All data was introduced into Foxpro database, and analyzed by Epi info (6.04) and SPSS. RESULTS: On-line measurement showed that the geometric mean (GM) of carbon disulfide exposure amounted to 12.73 mg/m3 in 'exposure' and 0.08 mg/m3 in 'non-exposure' worksites. These concentrations in the air were related to the subject's activities showing the highest levels when they had to open the shield windows of the spinning machines. Stationary exposure measurements of carbon disulfide in the spinning hall amounted to 23.29 mg/m3 GM (range 5.8-97.94 mg/m3). Personal exposure of spinners was about 17.3 mg/m3 GM. Comparing these methods, the personal exposure sampling could exactly express the exposure levels of the worker's contacting situation. The on-line measurement by multi-gas monitor might also be recommended to the factory as it has its own advantages of rapid and independent assessment, but it under-estimates the exposure level.

Air Pollution, Indoor↗
PubMed2001

Decreased carotid artery distensibility as a sign of early atherosclerosis in viscose rayon workers.

Carbon disulphide (CS(2)) is known to accelerate atherosclerosis and to increase the risk for cardiovascular diseases. To assess the effect of CS(2) on the functional (distensibility and compliance) and the structural (intima media thickness) properties of the common carotid artery, and blood pressure and lipid metabolism parameters, a cross-sectional study on 85 workers from a viscose rayon factory and 37 controls was carried out. Exposure to CS(2) was assessed by personal monitoring and was well below the threshold limit value-time weighted average. Carotid arterial wall properties were determined using a non-invasive ultrasound wall movement detector system. No significant effect of CS(2) on blood pressure, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol or triglycerides was found. Among the vascular parameters studied, only distensibility was significantly lower and heart rate was significantly higher in exposed subjects compared with the controls. In conclusion, occupational exposure to CS(2) may cause early alterations in arterial elastic properties in young individuals, and even before lipid and clinical findings have occurred, important functional changes in the vessel wall are present.

Adult↗
PubMed2001

Vascular changes in workers exposed to carbon disulfide.

AIM: To assess the effects of occupational exposure to carbon disulfide (CS2) concentrations below the threshold limit value (31 mg/m3) on the structural and the functional properties of the arteries, heart rate, blood pressure and lipids. METHODS: Study subjects were 85 male workers in the viscose industry and 35 men without such exposure. The CS2 concentration was determined by personal active sampling. From the common carotid artery diameter, the change in diameter (echography) during the heart cycle and the pulse pressure, local arterial distensibility and compliance were calculated. Global large and small artery elasticity were calculated from registrations of radial artery waveforms. Simultaneously, heart rate and blood pressure were recorded and blood samples were collected for lipid measurements. RESULTS: CS2 concentrations ranged from 2.34 to 32.4 mg/m3. No significant effect of CS2 on blood pressure, total cholesterol, HDL and LDL cholesterol or triglycerides was found. Among the vascular parameters under study, common carotid artery distensibility was significantly lower, and heart rate significantly higher in exposed workers compared to controls. The differences remained significant after adjustment for age, body mass index, smoking habits, alcohol consumption, heart rate and systolic blood pressure. Common carotid artery intima media thickness and global arterial indices did not differ significantly between the two groups. CONCLUSIONS: Exposure to CS2 under the current level may already cause alterations in common carotid artery elastic properties in apparently healthy individuals. Even before biochemical and clinical findings occur, important functional changes in the vessel wall were observed, at least in some vascular territories.

Adult↗
PubMed1999

Associations between haptoglobin polymorphism, lipids, lipoproteins and inflammatory variables.

The haptoglobin allele frequencies and the phenotype distribution were determined in 741 male Caucasian workers, aged 35 to 59 years. The association of the haptoglobin polymorphism with various clinical and biochemical parameters was investigated. Furthermore a possible interaction with the apo E polymorphism on lipid and lipoprotein traits was analysed. The frequency of Hp1 and Hp2 was found to be 0.401 and 0.599, respectively. The observed distribution of Hp types (Hp 1-1, 15.5%; Hp 2-1, 49.3%; Hp 2-2, 35.2%) was in Hardy-Weinberg equilibrium. Age, body mass index, smoking, alcohol intake and blood pressure were comparable between the three Hp groups. Subjects with Hp 2-2 had significantly higher serum total and free cholesterol concentration compared to those in other haptoglobin types (P = 0.006 and P = 0.003). Similarly, apo B levels were significantly higher among Hp 2-2 individuals (P = 0.02). No significant differences were demonstrated between the Hp phenotypes in HDL cholesterol, apo A-I, apo E, Lp(a), cholesteryl esters, fibrinogen and C-reactive protein concentrations, although for the latter an increase was noticed in Hp 2-2. The effects of Hp type and apo E type on Lp(a) and on free cholesterol levels were found to be significantly multiplicative, with the highest free cholesterol values observed in subjects having Hp 2-2 and the apo epsilon4 allele. Significantly lower Lp(a) levels were observed in individuals carrying Hp 1-1 and an epsilon2 allele than in subjects without the epsilon2 allele. In conclusion, haptoglobin polymorphism may play an important role in the regulation of lipoprotein metabolism and could contribute to the risk of coronary heart disease. Larger samples are needed to clarify the clinical relevance of the gene-gene (Hp-apo E) interaction on lipids and lipoproteins.

Adult↗
PubMed1999

Effects of a low-intensity worksite-based nutrition intervention.

Male employees from four local worksites were recruited to participate in a short-term and low-intensity nutrition intervention which focused on promoting low-fat dietary habits. The sites were randomized to control conditions or to the intervention programme that consisted of an individualized health risk appraisal, group sessions, mass media activities and environmental changes. Participants were seen before and three months after intervention to measure blood lipids, nutrition knowledge and dietary changes. Eighty-three per cent of all eligible subjects were screened (n = 770) and follow-up measures were obtained for 82%. The score for nutrition knowledge improved significantly in the intervention group. There was also a net reduction in the intake of total calories and in the percentage of energy from total fat. Reported intake of carbohydrates and proteins increased. For all employees assessed, there were no changes in mean total cholesterol level or fatty acid composition. Only among participants with hypercholesterolemia was a significant reduction in blood cholesterol observed. This low-intensity intervention programme achieved some self-reported dietary changes and was successful (at least in part because statistical regression needs to be considered) in obtaining a more short-term beneficial cholesterol level in employees at higher cardiovascular risk.

Adult↗
PubMed1999

Preliminary external quality assessment for the biological monitoring of carbon disulfide with urinary 2-thiothiazolidine-4-carboxylic acid.

Four laboratories have participated in an external quality control assessment for the determination of 2-thiothiazolidine-4-carboxylic acid (TTCA). TTCA is used as a biomarker for exposure to CS2. Thirteen different urine samples were analyzed by each laboratory. Ten of these were spiked with known amounts of TTCA, and had either a high or intermediate creatinine content. Two samples without any TTCA were used as controls and one sample was a pool of samples of urine from five employees occupationally exposed to CS2. The latter had unknown TTCA content. For each sample, TTCA and creatinine concentration were determined. The samples were supplied in three consecutive deliveries. Several samples were offered more than once. Thus, within-laboratory variability could be established for creatinine and TTCA determination and accuracy could be determined for TTCA analysis. Within-laboratory variability was low for all laboratories for creatinine, although laboratory D seemed to have a slight downward bias. Accuracy for TTCA was good for all laboratories. No significant mean deviation from the expected TTCA value was encountered. There does not seem to be any clear influence of the TTCA concentration level of the samples on the accuracy and within-laboratory variability. Two of the four laboratories (A and C) showed lower within-laboratory variability than the other two for TTCA, although coefficients of variation between replicated samples are high for these two laboratories as well. The laboratory giving the best accuracy, gave the highest within-laboratory variability. A non-systematic, random error is probably the source of this. The results of this preliminary study indicate that analysis of TTCA, although regarded as an established biomarker, can give biases and thus negatively interfere with inferred dose-effect or dose-response relationships in occupational epidemiology.

Bias↗
PubMed1998

The effect of age and lifestyle factors on plasma levels of apolipoprotein E.

BACKGROUND: The plasma concentration of apolipoprotein E might be an important risk factor for various chronic diseases, including coronary heart disease. OBJECTIVE: To investigate the role of lifestyle-related factors in determining concentrations of apolipoprotein E. METHODS: The independent effects of age and several lifestyle-related factors [body mass index (BMI), smoking, consumption of alcohol, physical activity, educational level and poly-unsaturated:saturated fatty acid intake ratio in diet] on the apolipoprotein E concentration were assessed for a sample of 757 middle-aged working men. Multiple log-linear regression models were fitted with additional correction for the apolipoprotein E polymorphism. RESULTS: The overall mean plasma concentration of apolipoprotein E was 3.44 mg/dl with mean levels varying from 2.42 mg/dl in men with the E4/4 phenotype to 8.32 mg/dl in men in the E2/2 group. In multivariate analysis apolipoprotein E levels were found to be significantly positively correlated to BMI (P<0.0001) and consumption of alcohol (P=0.04). The effect of age on the apolipoprotein E concentration was significantly quadratic (P=0.02) with highest levels found in the men aged 40-44 years (levels 13.3% greater than those in the men aged 35-39 years). Subjects with BMI in the range 27-30 kg/m2 had on average a 16.4% higher apolipoprotein E concentration than did men in the group with BMI lower than 23 kg/m2. This adjusted proportional increase amounted to 22.6% for the severely obese subjects (BMI>30 kg/m2). The independent effect of current smoking was only of borderline stat stical significance. CONCLUSIONS: These results indicate that age and lifestyle-related factors, such as BMI and to a lesser extent consumption of alcohol and smoking, should be taken into account as possible confounders in the study of the plasma concentration of apolipoprotein E as a risk factor for coronary heart disease.

Adult↗
PubMed1997

Intra-individual variability of fibrinogen levels.

Elevated fibrinogen concentrations are recognized as playing an important role in the pathogenesis of atherosclerosis. In the framework of a risk factor survey in 342 middle-aged working men, screened twice over a period of five months, plasma fibrinogen levels were found to be fairly unstable as large discrepancies between both measurements were observed. Due to a substantial proportion of within-person variability, the reliability coefficient was only R = 0.56. Repeatability was highest in higher educated and physically more active men. Our data suggest that the impact of elevated fibrinogen levels on the development of ischemic heart disease and stroke, is likely to be under-estimated.

Adult↗
PubMed1996

Apolipoprotein E polymorphism in middle-aged Belgian men: phenotype distribution and relation to serum lipids and lipoproteins.

Apo E phenotype was determined in 760 Belgian men, aged 35 to 59 years. Serum lipids and lipoproteins were related to the apo E polymorphism in 734 participants. By comparison with the most frequent apo E3/3 phenotype, the presence of the epsilon2 allele was associated with a lower serum total and non-HDL cholesterol, and with a lower apo B and a higher HDL cholesterol, independently of age, lifestyle factors and apo E concentration. In contrast, the presence of the epsilon4 allele was associated with a higher serum total and non-HDL cholesterol, and with a lower HDL cholesterol and a lower apo AI. The apo E phenotype explained 17.4% of the variance in apo E concentration; the proportion of the variance in total cholesterol, HDL cholesterol, apo AI and apo B levels explained by the apo E polymorphism was low but statistically significant. Among the lifestyle factors, waist to hip ratio was the only variable significantly associated with apo E concentration. The data suggest that besides the well-documented increasing effect on non-HDL cholesterol, the epsilon4 allele could further predispose to coronary heart disease through a decreasing effect on HDL while the epsilon2 allele could exert a protective influence through both a decreasing effect on non-HDL cholesterol and an increasing effect on HDL cholesterol.

Adult↗
PubMed1996

Determinants of lipoprotein(a) levels in a middle-aged working population.

BACKGROUND: The association between blood lipids, apolipoproteins, fibrinogen, life-style-related factors and lipoprotein(a) was assessed in a cohort of middle-aged men. METHODS: Male employees, working in local industry, were invited to participate in a health survey at their worksite. After exclusion of nine persons with prevalent diabetes and 14 subjects with a history of myocardial infarction or angina, data were available on 720 healthy Caucasian men. RESULTS: Lipoprotein(a) concentration was measured using an enzyme-linked immunosorbent assay (ELISA), and distribution was found to be highly skewed with a median level of 9 mg.dl-1 (mean level 23.1 mg.dl-1). The percentage of subjects with lipoprotein(a) levels higher than 30 mg.dl-1 was 23.6%. Univariate analysis showed a significant association between lipoprotein(a) and age, total cholesterol, apolipoprotein B and fibrinogen. However, no relationship was found with body mass index, waist to hip ratio, smoking, blood pressure, alcohol consumption, diet, HDL cholesterol, apolipoprotein AI and apolipoprotein E concentration or apolipoprotein E polymorphism. In multivariate analysis, In-transformed lipoprotein(a) correlated positively with apolipoprotein B (P < 0.0001) and fibrinogen (P = 0.004). Proportional changes in lipoprotein(a) concentration were predicted in relation to specified changes in biochemical and lifestyle variables. A 20 mg.dl-1 increase in apolipoprotein B and a 75 mg.dl-1 increase in fibrinogen levels were estimated to increase lipoprotein(a) concentration by 29.4% and 21.5% respectively. CONCLUSIONS: Our data confirm the existence of an independent association between lipoprotein(a) and fibrinogen and give evidence for correlation with apolipoprotein B.

Adult↗
PubMed1995

Relation of fibrinogen to lifestyles and to cardiovascular risk factors in a working population.

BACKGROUND: The association between fibrinogen and smoking behaviour, age, body mass index, blood pressure, heart rate and plasma lipid profile, was assessed in a cohort of middle-aged working men. METHODS: Seven hundred and forty five subjects were examined as part of a health intervention programme at the work-site. Nine subjects were excluded from the study because of prevalent diabetes. Correlates of plasma fibrinogen concentrations were evaluated through univariate and multivariate methods. RESULTS: In multiple regression analysis fibrinogen correlated with age, smoking behaviour, apolipoprotein B (apo B) apolipoprotein A-I (apo A-I) and lipoprotein (a) (Lp(a)) levels, which together explained 11% of the variation in fibrinogen concentration. From this model, fibrinogen concentration was associated with an increase of 13.6 mg/dl for every 10 years' increase in age, 28.2 mg/dl if a person smoked, and 4.6 mg/dl and 3.8 mg/dl with a 20 mg/dl rise in respectively apo B and Lp(a). A 20 mg/dl increase in apo A-I concentrations was estimated to be associated with a 6.0 mg/dl lower fibrinogen level. CONCLUSION: The data indicate that both biochemical and lifestyle factors are related to the plasma fibrinogen concentration; these interactions may explain partly the relationship between fibrinogen and cardiovascular disease.

Adult↗
PubMedDate not supplied

Cardiovascular effects in viscose rayon workers exposed to carbon disulfide.

The objectives of this study were to investigate the cardiovascular effects in workers currently exposed to carbon disulfide (CS2) below the threshold limit value (TLV) of 31 mg/m3 and to determine the prevalence of coronary heart disease (CHD) after long-term exposure. 172 men (91 workers exposed to CS2 in a viscose rayon factory and 81 referent workers) were examined using a medical and job history questionnaire, Rose's questionnaire, and electrocardiography at rest, and by measuring blood pressure and serum lipids and lipoproteins. Personal exposures were monitored simultaneously with active sampling and findings were analyzed according to the NIOSH 1600 method. As a result of technical and organizational improvements, personal CS2 exposures were well below the TLV (5.4-13.02 mg/m3). No significant effect of CS2 on blood pressure or lipids (total cholesterol, HDL and LDL cholesterol, triglycerides, and apolipoproteins AI and B) was found, even after allowance for confounding factors. The prevalence of CHD (ECG abnormalities and chest pain) was higher in the viscose rayon workers than in the workers with no exposure but reached statistical significance for men with exposure histories often years and more only (cumulative CS9 index > or = 150 mg/m3, the most highly exposed group). The findings suggest that the coronary risk is increased in workers previously exposed to high CS2 concentrations but not in those exposed to CS2 levels below the current TLV.

Adult↗