[Role of the occupational medicine in the prevention of diseases and accidents]. / Rôle de la Médecine du travail dans la prévention des maladies et des accidents.

Occupational medicine is an essential branch of preventive medicine that aims to protect the health of workers in the workplace. Any work situation exposes the worker to occupational hazards. The three levels of prevention applied in occupational medicine make it possible, together, to control risks. Primary prevention aims to prevent the occurrence of damage related to occupational risks, secondary prevention aims to early detect work-related health problems and in tertiary prevention, the objective is to limit the consequences of occupational risks or diseases already developed. It is not always possible to completely eliminate an occupational hazard. Regular medical examinations, at a frequency appropriate to the risks identified, meet this objective and therefore make it possible to detect work-related health problems or problems that could influence work. A proactive approach focused on prevention helps to reduce occupational risks, prevent work-related diseases, and to promote a healthy and safe work environment for all.

La médecine du travail est une branche essentielle de la médecine préventive qui vise à protéger la santé des travailleurs sur leur lieu de travail. Toute situation de travail expose le travailleur à des dangers professionnels. Les trois niveaux de prévention appliqués en médecine du travail permettent, ensemble, de maîtriser les risques. La prévention primaire vise à empêcher l'apparition des dommages liés aux risques professionnels, la prévention secondaire vise à détecter précocement les problèmes de santé liés au travail et en prévention tertiaire, l'objectif est de limiter les conséquences des risques professionnels ou des maladies déjà développées. Il n'est pas toujours possible de supprimer complètement un risque professionnel. Les examens médicaux réguliers, à une périodicité adaptée aux risques identifiés, répondent à cet objectif et permettent donc de détecter les éventuels problèmes de santé liés au travail ou qui pourraient influencer le travail. Une approche proactive axée sur la prévention contribue à réduire les risques professionnels, à prévenir les maladies liées au travail, et à promouvoir un environnement de travail sain et sécurisé pour tous.

PROBE Study: A Sentinel Surveillance System to Monitor Exposure of Belgian Employees to Hazardous Chemicals: A Feasibility Study.

OBJECTIVE: To test the feasibility of collecting reliable and representative data on exposure of Belgian employees to a selection of hazardous chemicals by using a sentinel surveillance method. METHOD: In PROBE (Hazardous chemical Products Register for Occupational use in Belgium), 47 occupational physicians were recruited as a sentinel network. Employees answered a web-based survey assessing their past week exposure to 22 chemicals. RESULTS: 47% employees were exposed to at least one chemical. The most frequently reported exposures was to diesel exhaust (14%). The exposed employees were mostly older men, with most exposed during production and manufacturing, and working in smaller companies. For diesel exhaust, wood dust, and crystalline silica, 54%, 32%, and 20% of the exposed employees, did not use collective/personal protective equipment. CONCLUSION: Sentinel surveillance is a feasible method for obtaining high-quality data on the exposure of Belgian employees to hazardous chemicals.

Psychosocial determinants predicting long-term sickness absence: a register-based cohort study.

BACKGROUND: This study assessed the psychosocial determinants as explanatory variables for the length of the work disability period. The aim was to estimate the predictive value of a selected set of psychosocial determinants from the Quickscan questionnaire for the length of the sick leave period. A comparison was also made with the most common biomedical determinant: diagnosis. METHODS: In a cohort study of 4 981 insured Belgian patients, the length of the sick leave was calculated using Kaplan-Meier. Predictive psychosocial determinants were selected using backward conditional selection in Cox regression and using concordance index values (C-index) we compared the predictive value of the biomedical to the psychosocial model in a sample subset. RESULTS: Fourteen psychosocial determinants were significantly (p<0.10) related to the length of the sick leave: health perception of the patient, physical workload, social support management, social support colleagues, work-health interference, psychological distress, fear of colleagues' expectations, stressful life-events, autonomy, learning and development opportunities, job satisfaction, workload, work expectations and expectation to return to work. The C-index of this biopsychosocial model including gender, age and labour status was 0.80 (CI: 0.78; 0.81) (n=4 981). In the subset of 2 868 respondents with diagnostic information, the C-index for the same model was .73 (CI: 0.71; 0.76) compared with 0.63 (CI: 0.61; 0.65) for the biomedical model. CONCLUSIONS: A set of 14 psychosocial determinants showed good predictive capacity (C-index: 0.80). Also, in a subset of the sample, the selected determinants performed better compared with diagnostic information to predict long-term sick leave (>6 months).

Correction to: Assessment of long-term sickness absence: content and face validity of a new questionnaire based on qualitative data from nominal groups.

In the original publication of this article [1] the author Marc Du Bois was omitted. In this correction article the author and the corresponding details are provided. The publisher apologizes to the readers and authors for the inconvenience.

Assessment of long-term sickness absence: content and face validity of a new questionnaire based on qualitative data from nominal groups.

BACKGROUND: Increasing rates of long-term sickness absence are a worldwide problem. Belgium is the first country in Europe that aims to screen its entire population of sick leavers (sick leave > 6 weeks) for the risk of long-term sickness absence in order to focus resources on the high-risk group and to provide adequate return-to-work support. Our aim was to investigate content and face validity of a newly designed questionnaire (Quickscan) using item prioritization of patients and professionals in the field of long-term sickness absence. This questionnaire was developed based on a review of the literature and existing instruments (Goorts et al, J Public Health Res 7:1419, 2018). METHODS: Qualitative data were collected using the nominal group technique. The data were gathered exploring factors that influence return-to work restrictions or opportunities. RESULTS: Participants indicated 20 out of 21 of the questionnaire factors as important reasons that might influence the return-to-work process. Additionally, 16 factors were discussed that were not yet included in the Quickscan but that might provide useful information on return-to-work issues, according to the participants. In the prioritization of items, we found considerable diversity among participants. CONCLUSIONS: Our findings demonstrate the validity of the Quickscan items to ask patients about important return-to-work barriers or opportunities. However, additional factors were identified that may improve the assessment of risk for long-term sickness absence.

Quickscan assesses risk factors of long-term sickness absence: A cross-sectional (factorial) construct validation study.

OBJECTIVES: The number of sick-listed employees has increased dramatically worldwide. Therefore, many countries aim to stimulate early and sustainable return to work opportunities to obtain better health outcomes and lower costs for disability pensions. To effectively orientate resources to patients with a high risk of not resuming work spontaneously, it is necessary to screen patients early in their sickness absence process. In this study, we validate "Quickscan", a new instrument to assess return-to-work needs and to predict risks of long-term sick leave. METHODS: As part of the Quickscan validation process, we tested and compared the reliability and construct validity of the questionnaire in two different populations. First, we conducted a cross-sectional study in which the screening instrument was sent to sick-listed individuals in healthcare insurance. In a second cross-sectional study, sick-listed workers who consulted the occupational health physician for return-to-work assessment were asked to fill out the questionnaire. We compared both samples for descriptive statistics: frequencies, means and standard deviations. Reliability of the scales was calculated using Cronbach's alpha. Confirmatory factor analysis was performed to evaluate the construct (factorial) validity of the studied scales using software package AMOS 24. RESULTS: The screening tool was shown to be an instrument with reliable scales (except for the perfectionism and health perception patient scale) in both populations. The construct validity was satisfactory: we found that the hypothesized measurement models with the theoretical factors fitted the data well in both populations. In the first sample, the model improved for scales concerning stressful life events and showed worse fit for person-related factors. Work-related factors and functioning factors both showed similar fit indices across samples. We found small differences in descriptive statistics, which we could explain by the differences in characteristics of both populations. CONCLUSIONS: We can conclude that the instrument has considerable potential to function as a screening tool for disability management and follow-up of sick-leave, provided that some adaptations and validation tests are executed.

Quickscan Assesses Risk of Long-Term Sickness Absence: A Cross-Sectional Validation Study.

OBJECTIVE: Increasing long-term sickness absence in many countries asks for specific measures regarding return-to work. METHODS: The risk of long-term sickness absence was assessed using a questionnaire containing work-related, function-related, stressful life-events-related, and person-related factors. Additionally, workers' occupational health physician estimated the worker's chances for work resumption. Reliability, construct, and criterion validity of the questionnaire were measured. RESULTS: Two hundred seventy-six patients and 35 physicians participated in the study. The reliability was satisfying (α > 0.70) for all scales, except for perfectionism (α = 0.62). The results of the CFAs showed that the hypothesized factor models fitted the data well. Criterion validity tests showed that eight predictors significantly related to the estimation of the occupational physicians (ρ < 0.05). CONCLUSIONS: The scales of the questionnaire are reliable and valid, and may be implemented to assess sick-listed workers at risk who might benefit from a rehabilitation program.

Screening for the risk on long-term sickness absence.

Background: Long-term sickness absence is a growing concern in Belgium and other European countries. Since 2017, Belgian physicians of the sickness funding organisations are required to assess the re-integration possibilities within the first two months of sickness absence. Given the shortage of physicians in the assessment of work disability and the growing number of people in sickness absence, there is a need for a triage tool, allowing to assign return-to work support to patients having a high-risk profile not to resume work. Methods/design: The current study comprises a comprehensive validation process of a screening tool that supports Belgian physicians in guiding people back to work. The study consists of a theoretical construct validation (face validity and content validity), and an empirical construct validation (concurrence validity, factorial validity, predictive validity, hypothesis testing validity and known- group validity). Expected impact of the study for Public Health: The screening instrument assessing the risk for long-term sickness absence is a tool developed to support physicians who work for sickness funds and for occupational health and safety organisations. Both professionals play an important role in the return to work process and the prevention of long-term sickness absence. The screening tool aims at making a distinction between people who will resume their work independently and people who will need support to do so. Generation of this prediction model will help physicians to focus effort and resources in the high-risk group. Results may also help understand the relationship between the biopsychosocial model and long-term sick-leave.

Characterization and quality control of antibodies used in ChIP assays.

We present here the very robust characterization and quality control (QC) process that we have established for our polyclonal antibodies, which are mainly directed against targets relevant to the epigenetics field such as modified histones, modifying enzymes, and chromatin-interacting proteins. The final purpose of the characterization and QC is to label antibodies as chromatin immunoprecipitation (ChIP) grade. Indeed, the ChIP method is extensively used in epigenetics to study gene regulation and relies on the use of antibodies to select the protein of interest and then precipitate and identify the DNA associated to it. We have optimized in-house all protocols and reagents needed from the first to the last step of antibody characterization. First, following immunizations, the rabbit crude serum is tested for immune response. Whether or not the antibody is specific is determined in further characterizations. Then, only specific antibodies are tested in ChIP using an optimized method which is ideal for antibody screening. Once QC is established for one antibody, it is used to similarly characterize each antibody batch in order to supply researchers in a reproducible manner with validated antibodies. All in all, this demonstrates that we develop epigenetics research tools based on everyday's researcher's needs by providing batch-specific fully characterized ChIP-grade antibodies.

Preliminary characterization of jejunocyte and colonocyte cell lines isolated by enzymatic digestion from adult and young cattle.

In the present study we developed an enzymatic approach (through the use of collagenase and dispase) to isolate bovine intestinal epithelial cells. Using this method, freshly isolated jejunocytes could be distinguished from simultaneously isolated colonocytes, as the jejunocytes specifically exhibited the small intestinal peptidase gene transcript, as well as an active alkaline phosphatase. The transformation of both types of cell suspension was performed by retroviral infection, using reproduction-defective viruses bearing the gene coding for the large T antigen of the leukaemia simian virus (SV40). The success of the transfection was demonstrated by (1) a significant increase in cell passage numbers (52-53 vs. 7 passages for non-transfected cells), (2) the detection of both the large T transcript and the large T antigen in transformed cells. Possible contamination and progressive substitution of bovine primocultures by non-bovine lineages available in the laboratory was excluded, as the transformed cells presented a bovine typical karyotype. Most transfected cells kept an epithelial morphology after transformation. They also maintained the expression of FABP and enterocyte specific enzymes (brush-border associated maltase and IAP). However, levels of specific activity of these enzymes were low, suggesting that cell differentiation is not completely achieved under the applied culture conditions.

Immunochemical, biomolecular and biochemical characterization of bovine epithelial intestinal primocultures.

BACKGROUND: Cultures of enterocytes and colonocytes represent valuable tools to study growth and differentiation of epithelial cells. In vitro models may be used to evaluate passage or toxicity of drugs, interactions of enteropathogenes bacteria strains with intestinal epithelium and other physiologic or pathologic phenomenon involving the digestive tract. RESULTS: Cultures of bovine colonocytes and jejunocytes were obtained from organoid-enriched preparations, using a combination of enzymatic and mechanical disruption of the intestine epithelium, followed by an isopicnic centrifugation discarding most single cells. Confluent cell monolayers arising from plated organoids exhibited epithelium typical features, such as the pavement-like structure, the presence of apical microvilli and tight junctions. Accordingly, cells expressed several markers of enterocyte brush border (i.e. maltase, alkaline phosphatase and fatty acid binding protein) as well as an epithelial cytoskeleton component (cytokeratin 18). However, enterocyte primocultures were also positive for the vimentin immunostaining (mesenchyme marker). Vimentin expression studies showed that this gene is constitutively expressed in bovine enterocytes. Comparison of the vimentin expression profile with the pattern of brush border enzymes activities, suggested that the decrease of cell differentiation level observed during the enterocyte isolation procedure and early passages of the primoculture could result from a post-transcriptional de-repression of vimentin synthesis. The low differentiation level of bovine enterocytes in vitro could partly be counteracted adding butyrate (1-2 mM) or using a glucose-deprived culture medium. CONCLUSION: The present study describes several complementary approaches to characterize bovine primary cultures of intestinal cells. Cultured cells kept their morphologic and functional characteristics during several generations.

Modulation of intestinal urea cycle by dietary spermine in suckling rat.

Argininosuccinate synthetase, an ubiquitous enzyme in mammals, catalyses the formation of argininosuccinate, the precursor of arginine. Arginine is recognised as an essential amino acid in foetuses and neonates, but also as a conditionally essential amino acid in adults. Argininosuccinate synthetase is initially expressed in enterocytes during the developmental period, it disappeared from this organ then appeared in the kidneys. Although the importance of both intestinal and renal argininosuccinate synthetases has been recognised for a long time, nutrients have not yet been identified as inducers of the gene expression. In the context of a proteomic screening of intestinal modifications induced by dietary spermine in suckling rats, we showed that argininosuccinate synthetase and carbamoyl phosphate synthase disappeared from enterocytes after this treatment. The disappearance of argininosuccinate synthetase in small intestine was confirmed by immunodetection. Expression of carbamoyl phosphate synthase and argininosuccinate synthetase coding genes decreased also after spermine administration. Expression of other urea cycle enzyme coding genes was modulated by spermine administration: argininosuccinate lyase decreased and arginase increased. Our results fit with the developmental variation of argininosuccinate synthetase and carbamoyl phosphate synthase. Modulation of the gene expression for several urea cycle enzymes suggests a coordination between all the pathway steps and switch toward polyamine (or proline and glutamate) biosynthesis from ornithine.