A hybrid expert approach for retrospective assessment of occupational exposures in a population-based case-control study of cancer

BACKGROUND

While the expert-based occupational exposure assessment approach has been considered the reference method for retrospective population-based studies, its implementation in large study samples has become prohibitive. To facilitate its application and improve upon it we developed, in the context of a Montreal population-based study of prostate cancer (PROtEuS), a hybrid approach combining job-exposure profiles (JEPs) summarizing expert evaluations from previous studies and expert review. We aim to describe the hybrid expert method and its impacts on the exposures assigned in PROtEuS compared to those from a previous study coded using the traditional expert method.

METHODS

Applying the hybrid approach, experts evaluated semi-quantitative levels of confidence, concentration and frequency of exposure to 313 agents for 16,065 jobs held by 4005 subjects in PROtEuS. These assessments were compared to those from a different set of jobs coded in an earlier study of lung cancer, conducted on the same study base, for 90 blue-collar occupations and 203 agents. Endpoints evaluated included differences in the number of exposures and in the distribution of ratings across jobs, and the within-occupation variability in exposure.

RESULTS

Compared to jobs from the lung cancer study, jobs in PROtEuS had on average 0.3 more exposures. PROtEuS exposures were more often assigned definite confidence ratings, but concentration and frequency levels tended to be lower. The within-occupation variability in ratings assigned to jobs were lower in PROtEuS jobs for all metrics. This was particularly evident for concentration, although considerable variability remained with over 40% of occupation/agent cells in PROtEuS exposed at different levels. The hybrid approach reduced coding time by half, compared to the traditional expert assessment.

CONCLUSIONS

The new hybrid expert approach improved on efficiency and transparency, and resulted in greater confidence in assessments, compared to the traditional expert method applied in an earlier study involving a similar set of jobs. Assigned ratings were more homogeneous with the hybrid approach, possibly reflecting clearer guidelines for coding, greater coherence between experts and/or reliance on summaries of past assessments. Nevertheless, significant within-occupation variability remained with the hybrid approach, suggesting that experts took into account job-specific factors in their assessments.

Physical activity and lung cancer risk in men and women

PURPOSE

Although evidence has accumulated that recreational physical activities (PA) may reduce lung cancer risk, there is little evidence concerning the possible role of a potentially more important source of PA, namely occupational PA. We investigated both recreational and lifetime occupational PA in relation to lung cancer risk in a population-based case-control study in Montreal, Canada (N_CASES = 727; N_CONTROLS = 1,351).

METHODS

Unconditional logistic regression was used to estimate odds ratios (OR), separately for men and women, adjusting for smoking, exposure to occupational carcinogens, and sociodemographic and lifestyle factors.

RESULTS

In both sexes, increasing recreational PA was associated with a lower lung cancer risk (OR_MEN = 0.66, 95% confidence interval (CI) 0.47-0.92; OR_WOMEN = 0.55, 95% CI 0.34-0.88, comparing the highest versus lowest tertiles). For occupational PA, no association was observed among women, while increasing occupational PA was associated with increased risk among men (OR_MEN = 1.96, 95% CI 1.27-3.01). ORs were not modified by occupational lung carcinogen exposure, body mass index, and smoking level; results were similar across lung cancer histological types.

CONCLUSIONS

Our results support the previous findings for recreational PA and lung cancer risk. Unexpectedly, our findings suggest a positive association for occupational PA; this requires replication and more detailed investigation.

Green Jobs: Definition and Method of Appraisal of Chemical and Biological Risks

In the wake of sustainable development, green jobs are developing rapidly, changing the work environment. However a green job is not automatically a safe job. The aim of the study was to define green jobs, and to establish a preliminary risk assessment of chemical substances and biological agents for workers in Quebec. An operational definition was developed, along with criteria and sustainable development principles to discriminate green jobs from regular jobs. The potential toxicity or hazard associated with their chemical and biological exposures was assessed, and the workers' exposure appraised using an expert assessment method. A control banding approach was then used to assess risks for workers in selected green jobs. A double entry model allowed us to set priorities in terms of chemical or biological risk. Among jobs that present the highest risk potential, several are related to waste management. The developed method is flexible and could be adapted to better appraise the risks that workers are facing or to propose control measures.

Effort--reward imbalance and medically certified absence for mental health problems: a prospective study of white-collar workers

OBJECTIVE

Little is known about the effects of psychosocial work factors on objectively assessed mental health problems leading to medically certified absence. Only one study has evaluated the prospective effects of effort-reward imbalance (ERI) at work with regards to this outcome. The present study aimed to evaluate the effects of ERI on the incidence of medically certified absence for mental health problems.

METHODS

The study included 2086 white-collar workers (63.3% women) employed in public organisations in Quebec city. Participants were followed over a 9-year period. Medical absences from work were collected from employers' files and psychosocial factors were measured using the ERI questionnaire. Cox regression models were used to estimate the incidence of certified sickness absence due to mental health problems that lasted 5 workdays or more, while controlling for confounders.

RESULTS

Workers exposed to ERI had a higher risk of a first spell of medically certified absence for mental health problems (HR=1.38, 95% CI 1.08 to 1.76) compared with unexposed workers. Low reward was significantly associated with a high risk among men (HR=2.80, 95% CI 1.34 to 5.89) but not in women. (HR=1.24, 95% CI 0.90 to 1.73). Effort at work had no effect on certified absence. All these effects were adjusted for potential confounders.

CONCLUSIONS

ERI and low reward at work were prospectively associated with medically certified absence for mental health problems. These effects seem to differ by gender. Primary prevention that is aimed at reducing these stressors should be considered to help reduce the incidence of such severe mental health problems.

Identification of workers exposed concomitantly to heat stress and chemicals

In the context of climate change, concomitant exposure to heat stress and chemicals takes on great importance. However, little information is available in this regard. The purpose of this research, therefore, was to develop an approach aimed at identifying worker groups that would be potentially most at risk. The approach comprises 5 consecutive steps: - Establishment of a list of occupations for all industry sectors - Determination of heat stress parameters - Identification of occupations at risk of heat stress - Determination of exposure to chemicals - Identification of occupations potentially most at risk. Overall, 1,010 occupations were selected due to their representativeness of employment sectors in Québec. Using a rating matrix, the risk stemming from exposure to heat stress was judged "critical" or "significant" for 257 occupations. Among these, 136 occupations were identified as showing a high potential of simultaneous exposure to heat stress and chemicals. Lastly, a consultation with thirteen experts made it possible to establish a list of 22 priority occupations, that is, 20 occupations in the metal manufacturing sector, as well as roofers and firefighters. These occupations would merit special attention for an investigation and evaluation of the potential effects on workers' health.

Development and implementation of a participative intervention to improve the psychosocial work environment and mental health in an acute care hospital

OBJECTIVES

To describe the development and implementation phases of a participative intervention aimed at reducing four theory grounded and empirically supported adverse psychosocial work factors (high psychological demands, low decision latitude, low social support, and low reward), and their mental health effects.

METHODS

The intervention was realised among 500 care providers in an acute care hospital. A prior risk evaluation was performed, using a quantitative approach, to determine the prevalence of adverse psychosocial work factors and of psychological distress in the hospital compared to an appropriate reference population. In addition, a qualitative approach included observation in the care units, interviews with key informants, and collaborative work with an intervention team (IT) including all stakeholders.

RESULTS

The prior risk evaluation showed a high prevalence of adverse psychosocial factors and psychological distress among care providers compared to a representative sample of workers from the general population. Psychosocial variables at work associated with psychological distress in the prior risk evaluation were high psychological demands (prevalence ratio (PR) = 2.27), low social support from supervisors and co-workers (PR = 1.35), low reward (PR = 2.92), and effort-reward imbalance (PR = 2.65). These results showed the empirical relevance of an intervention on the four selected adverse psychosocial factors among care providers. Qualitative methods permitted the identification of 56 adverse conditions and of their solutions. Targets of intervention were related to team work and team spirit, staffing processes, work organisation, training, communication, and ergonomy.

CONCLUSION

This study adds to the scarce literature describing the development and implementation of preventive intervention aimed at reducing psychosocial factors at work and their health effects. Even if adverse conditions in the psychosocial environment and solutions identified in this study may be specific to the healthcare sector, the intervention process used (participative problem solving) appears highly exportable to other work organisations.

Effectiveness of a participative intervention on psychosocial work factors to prevent mental health problems in a hospital setting

OBJECTIVES

To assess the effectiveness of a workplace intervention aimed at reducing adverse psychosocial work factors (psychological demands, decision latitude, social support, and effort-reward imbalance) and mental health problems among care providers.

METHODS

A quasi-experimental design with a control group was used. Pre-intervention (71% response rate), and one-year post-intervention measures (69% response rate) were collected by telephone interviews.

RESULTS

One year after the intervention, there was a reduction of several adverse psychosocial factors in the experimental group, whereas no such reduction was found in the control group. However, there was a significant deterioration of decision latitude and social support from supervisors in both experimental and control groups. There was also a significant reduction in sleeping problems and work related burnout in the experimental hospital, whereas only sleeping problems decreased in the control group while both client related and personal burnout increased in this hospital. The comparison between the experimental and control groups, after adjusting for pre-intervention measures, showed a significant difference in the means of all psychosocial factors except decision latitude. All other factors were better in the experimental group.

CONCLUSION

Results suggest positive effects of the intervention, even though only 12 months have passed since the beginning of the intervention. Follow up at 36 months is necessary to evaluate whether observed effects are maintained over time. In light of these results, we believe that continuing the participative process in the experimental hospital will foster the achievement of a more important reduction of adverse psychosocial factors at work. It is expected that the intensity of the intervention will be directly related to its beneficial effects. Long term effects will however depend on the willingness of management and of staff to appropriate the process of identifying what contributes to adverse psychosocial factors at work and to adopt means to reduce them.

Les caractéristiques du travail et la santé des agents en services de détention

BACKGROUND

The association between the psychosocial work environment and mental health problems has been well documented over the past years. Karasek and Theorell's job strain model and Siegrist's effort/reward imbalance model have been associated to several physical and mental health problems. Moreover, in the last decade, the Quebec correctional services sector has known an important increase in sickness benefit claims for mental health problems. This study aimed to describe the psychosocial work characteristics and health of Quebec correctional officers and to determine the occupational risk factors associated to psychological distress among them.

METHODS

This cross-sectional study was realized among 1034 correctional officers from 18 prisons in the province of Quebec, 668 men and 366 women. The response rate was 76%. Psychological demands, decision latitude, social support at work, reward, and psychological distress have been documented by telephone interviews during spring 2000.

RESULTS

Correctional officers were more exposed to adverse psychosocial factors at work than a comparable sample of Quebec workers and they reported more health problems. Results showed that the same sources of psychological distress affected men and women, but sometimes at different degrees. High psychological demands combined with low or high decision latitude, and effort/reward imbalance were associated to psychological distress independently of potential confounding factors. Among other work factors associated to the report of high psychological distress among correctional officers were low social support at work, and conflicts with colleagues and superiors.

CONCLUSION

Many adverse psychosocial factors at work were in excess among correctional officers compared to workers from the general population. These factors, also related to high levels of psychological distress, could be addressed with the goal of primary prevention of mental health problems at work.

Oxidation of lignin model compounds by organic and transition metal-based electron transfer mediators

We have studied the oxidation of lignin model compounds by organic and transition metal-based mediators using either an enzyme or an electrolysis cell as the mediator oxidizing agent. Electrolysis of inorganic mediator seems a promising technology for pulp delignification.

[Impact of occupational stress on health status in Canada]

Studies have shown that high psychological demands and low decision latitude may be involved in the development of major health problems. The objective of the current study was to describe the importance of these factors among the Canadian working population. The sample included 7,250 participants from the National Population Health Survey (NPHS) of 1994-95. Women were significantly more exposed than men to high psychological demands (56% versus 49%), to low decision latitude (61% versus 49%), and to these two factors simultaneously (33% versus 22%). The exposure to each of these factors was more frequent among younger and less educated people. Simultaneous exposure to both factors was more frequent among younger people and those with intermediate education level. There was a socio-economic gradient for the exposition to these factors. Some jobs with the highest exposure were identified.

Job strain and sickness absence among nurses in the province of Québec

BACKGROUND

Using Karasek's job strain model, the objective of the study was to determine whether nurses exposed to job strain had a higher incidence of sick leave than nurses not exposed.

METHODS

The design was longitudinal. Data on sick leave were collected for 1,793 nurses for a 20-month period: short-term leaves and certified sick leaves. The Job Content Questionnaire was used to measure psychological demands, job decision latitude, and social support at work.

RESULTS

Short-term sick leaves were associated with job strain (incidence density ratio (IDR) = 1.20) and with low social support at work (IDR = 1.26). Certified sick leaves were also significantly associated with low social support at work (IDR = 1.27 for all diagnoses and IDR = 1.78 for mental health diagnoses).

CONCLUSIONS

Our results support the association between job strain and short-term sick leaves. The association with certified sick leaves is also significant for subgroups of nurses with specific job characteristics. Social support at work, although associated with all types of sick leaves measured, does not modify the association between job strain and absence.

Job strain and evolution of mental health among nurses

The objective of this 2nd phase of a 2-year study among female nurses was to provide further empirical validation of the demands-control and social support model. The association of job strain with psychological problems and the potential modifying role of social support at work were examined. A questionnaire was sent at the workplace to 1,741 nurses. The same associations were found between psychological demands, decision latitude, and a combination of the 2 with psychological distress and emotional exhaustion for current exposure and for cumulative exposure. Social support had a direct effect on these psychological symptoms but did not modify their association with job strain. Longitudinal and prospective data are needed to study the occurrence and persistence of health problems when exposure is maintained or retrieved.

Job strain and evolution of mental health among nurses

The objective of this 2nd phase of a 2-year study among female nurses was to provide further empirical validation of the demands-control and social support model. The association of job strain with psychological problems and the potential modifying role of social support at work were examined. A questionnaire was sent at the workplace to 1,741 nurses. The same associations were found between psychological demands, decision latitude, and a combination of the 2 with psychological distress and emotional exhaustion for current exposure and for cumulative exposure. Social support had a direct effect on these psychological symptoms but did not modify their association with job strain. Longitudinal and prospective data are needed to study the occurrence and persistence of health problems when exposure is maintained or retrieved.

[The professional life and the health of nurses since the transformation of the Québec health system.]

Over the last years, the Quebec health system has gone through a period of transformation aimed at cost reduction and better efficiency. The present study describes the effects of the transformation on the professional life and on the health of nurses in the Quebec City urban area. Despite a cross-sectional study not allowing links from cause to effect and despite the fact that the study only includes nurses who were still employed by institutions, the research shows an increase of the prevalence of a higher level of psychological distress in nurses since the beginning of the transformation. Interventions in the work place should be geared to professional factors that nurses identify as problematical.

Job strain, psychological distress, and burnout in nurses

The first phase of this longitudinal study consisted of a questionnaire completed by a cohort of 1,891 nurses (aged 23-65 years) from six acute care hospitals from the province of Québec. This study was set up to investigate the association between the psychosocial environment of work and mental health. After adjusting for confounding factors, a combination of high psychological demands and low decision latitude was associated with psychological distress and emotional exhaustion, one of the three dimensions of burnout. Social support at work, although associated with each of the mental health indicators, did not modify their association with job strain. The present study identified conditions of the work environment that are modifiable and provide the basis for interventions that focus beyond the modification of individual coping strategies.

Electrochemical analysis of the interactions of laccase mediators with lignin model compounds

The mechanism of oxidation of lignin by laccase and mediator has been investigated by cyclic voltammetry and bulk electrolysis. Electrochemical properties and reactivities of the two mediators 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) and 1-hydroxybenzotriazole (HBT) were studied and their intermediates responsible for lignin oxidation were characterized. ABTS was oxidized first to the cation radical (ABTS+.) and then to the dication (ABTS2+). The two oxidized species are relatively stable and electrochemically reversible, with formal redox potentials (E0' vs Ag/AgCl) of 472 mV for ABTS/ABTS+. and 885 mV for ABTS+./ABTS2+. The dication was shown to be the intermediate responsible for the oxidation of the non-phenolic lignin model compound veratryl alcohol, whereas the cation radical reacted only with phenolic structures in lignin. Cyclic voltammetry of HBT shows only one oxidation peak at 878 mV, but unlike ABTS, the oxidized intermediate was not stable and decayed rapidly. The radical intermediate of HBT was shown to catalyze the oxidation of veratryl alcohol to veratraldehyde. The kinetics of homogeneous redox catalysis of mediators and veratryl alcohol were estimated. ABTS-mediated lignin oxidation at the redox potential of laccase (585 mV) was shown to be possible, but at a very slow rate, as previously reported for laccase and mediator.

Reactivities of various mediators and laccases with kraft pulp and lignin model compounds

Laccase-catalyzed oxygen delignification of kraft pulp offers some potential as a replacement for conventional chemical bleaching and has the advantage of requiring much lower pressure and temperature. However, chemical mediators are required for effective delignification by laccase, and their price is currently too high at the dosages required. To date, most studies have employed laccase from Trametes versicolor. We have found significant differences in reactivity between laccases from different fungi when they are tested for pulp delignification in the presence of the mediators 2,2(prm1)-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) and 1-hydroxybenzotriazole (HBT). A more detailed study of T. versicolor laccase with ABTS and HBT showed that HBT gave the most extensive delignification over 2 h but deactivated the enzyme, and therefore a higher enzyme dosage was required. Other mediators, including 1-nitroso-2-naphthol-3,6-disulfonic acid, 4-hydroxy-3-nitroso-1-naphthalenesulfonic acid, promazine, chlorpromazine, and Remazol brilliant blue, were also tested for their ability to delignify kraft pulp. Studies with dimeric model compounds indicated that the mechanisms of oxidation by ABTS and HBT are different. In addition, oxygen uptake by laccase is much slower with HBT than with ABTS. It is proposed that the dication of ABTS and the 1-oxide radical of HBT, with redox potentials in the 0.8- to 0.9-V range, are required for pulp delignification.

Women physicians in Quebec

This article presents the results of a qualitative study on women physicians in Quebec which aimed to go beyond a mere statistical description of the tendencies observed in their practices. It proposes an interpretation of their discourses on their practice and its context bringing to light the interdependence of individual strategies and structural constraints. We met 30 women physicians and eight men physicians asking them to talk freely about their personal and professional experience. The data reveal how the individual characteristics and interests of women physicians prevail in their decisions at key moments in their lives which have repercussions on the shaping of their practice. These moments include admission into the faculty of medicine, training, professional orientation and the choice of a specialized field, organization of professional practice and personal life. The medical practice of women is constructed through these choices and the gender variable plays a more or less significant role at each stage of this construction. Their distinctive choices reflect how gender relations are reproduced in the private sphere and the interactions between their private and professional lives. According to our participants, a difference lies in the place occupied by their profession in women and men physicians' lives. The private life of women physicians appears to be closely linked to their decisions regarding the organization of their professional life and as a result to the health services they provide, suggesting they have their own way of "being a physician". The individual nature of the strategies they adopt can have, at a collective level, consequences on the planning and the distribution of medical resources in the publicly managed health care system in Quebec while raising the global issue of gendered division of labor.

Job strain and psychological distress in white-collar workers

OBJECTIVES

In line with Karasek's job strain model, the objective of the study was to determine whether workers submitted to high job strain, a combination of high psychological demand and low decision latitude, develop more psychological distress than workers not submitted to high job strain. A second objective was to determine whether social support at work modifies the association between job strain and psychological distress.

METHODS

The design was cross-sectional and included white-collar workers in the Québec city area. A self-administered 26-item questionnaire (the Job Content Questionnaire) measured psychological demand, decision latitude, and social support at work. Psychological distress was measured by the Psychiatric Symptom Index, a 14-item self-administered instrument.

RESULTS

Among the 2889 participants, the prevalence of psychological distress was 27.8%. High job strain was present in 20.5% of the subjects. The crude odds ratio (OR) of high job strain with psychological distress was 3.52 [95% confidence interval (95% CI) 2.54-4.88]. The OR adjusted for age, gender, employment status, occupation, social support at work, nonwork social support, cynicism, hostility, domestic load, and stressful life events during the last 12 months was still significant (OR 2.45, 95% CI 1.66-3.62).

CONCLUSIONS

Our results support the association between job strain and psychological distress. Social support at work, although significantly associated with psychological distress, did not modify the association between job strain and psychological distress.

Production and Characterization of Trametes versicolor Mutants Unable To Bleach Hardwood Kraft Pulp

Protoplasts of the monokaryotic strain 52J of Trametes versicolor were treated with UV light and screened for the inability to produce a colored precipitate on guaiacol-containing agar plates. Mutants unable to oxidize guaiacol had absent or very low secretion of laccase and manganese peroxidase (MnP) proteins. All isolates unable to secrete MnP were also unable to bleach or delignify kraft pulp. One mutant strain, M49, which grew normally but did not oxidize guaiacol, was tested further with a number of other substrates whose degradation has been associated with delignification by white rot fungi. Compared with the parent, 52J, mutant M49, secreting no MnP and low laccase, could not brighten or delignify kraft pulp, produced less ethylene from 2-keto methiolbutyric acid, released much less (sup14)CO(inf2) from [(sup14)C]DHP (a synthetic lignin-like polymerizate), and produced much less methanol from pulp. This mutant also displayed decreased abilities to oxidize the dyes poly B-411, poly R-478, and phenol red compared with the wild-type strain and was also unable to decolorize kraft bleachery effluent or mineralize its organochlorine. Addition of purified MnP in conjunction with H(inf2)O(inf2), MnSO(inf4), and an Mn(III) chelator to M49 cultures partially restored methanol production, pulp delignification, and biobleaching in some cases.

Lignin oxidation by laccase isozymes from Trametes versicolor and role of the mediator 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) in kraft lignin depolymerization

Two laccase isozymes (I and II) produced by the white-rot fungus Trametes versicolor were purified, and their reactivities towards various substrates and lignins were studied. The N-terminal amino acid sequences of these enzymes were determined and compared to other known laccase sequences. Laccase II showed a very high sequence similarity to a laccase which was previously reported to depolymerize lignin. The reactivities of the two isozymes on most of the substrates tested were similar, but there were some differences in the oxidation rate of polymeric substrates. We found that the two laccases produced similar qualitative effects on kraft lignin and residual lignin in kraft pulp, with no evidence of a marked preference for depolymerization by either enzyme. However, the presence of the mediator 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) prevented and reversed the polymerization of kraft lignin by either laccase. The delignification of hardwood and softwood kraft pulps with the two isozymes and the mediator was compared; either laccase was able to reduce the kappa number of pulp, but only in the presence of 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate).

Physical, mental, and reproductive health of Québec women physicians

In order to address the personal and professional characteristics as well as the physical, mental, and reproductive health of women physicians, a survey was mailed to a random sample of 3,000 women and men physicians in the province of Québec, Canada. The data obtained from women physicians were compared with those from men physicians and with available data on a comparable subgroup of professional women. The sociodemographic and health data highlight the physical and mental health status of women physicians. These data, which provide a global picture of Québec women physicians, indicate that in spite of the challenges, they seem to reconcile their professional and parental activities without major repercussions on their physical and mental health.

Manganese Peroxidase, Produced by Trametes versicolor during Pulp Bleaching, Demethylates and Delignifies Kraft Pulp

Previous work has shown that Trametes ( Coriolus ) versicolor bleaches kraft pulp brownstock with the concomitant release of methanol. In this work, the fungus is shown to produce both laccase and manganese peroxidase (MnP) but not lignin peroxidase during pulp bleaching. MnP production was enhanced by the presence of pulp and/or Mn(II) ions. The maximum level of secreted MnP was coincident with the maximum rate of fungal bleaching. Culture filtrates isolated from bleaching cultures produced Mn(II)- and hydrogen peroxide-dependent pulp demethylation and delignification. Laccase and MnP were separated by ion-exchange chromatography. Purified MnP alone produced most of the demethylation and delignification exhibited by the culture filtrates. On the basis of the methanol released and the total and phenolic methoxyl contents of the pulp, it appears that MnP shows a preference for the oxidation of phenolic lignin substructures. The extensive increase in brightness observed in the fungus-treated pulp was not found with MnP alone. Therefore, either the MnP effect must be optimized or other enzymes or compounds from the fungus are also required for brightening.

Certified sick leave as a non-specific morbidity indicator: a case-referent study among nurses

A case-referent study assessed the association between medically certified sick leave from work and some occupational characteristics--namely, two work load indices (nurse patient ratio and patients' average duration of stay) and hospital and care unit. Study participants were nurses from seven general hospitals in Québec City who had been employed for at least six months at the time of study. Cases (n = 184) experienced at least one episode of medically certified sick leave for a diagnosis "most likely to be related to work load" between 1 January 1984 and 31 May 1987. Referents (n = 1165) were chosen from subjects who had no such leave, whatever the medical reason, and were matched to cases by the incidence density sampling method. Occupational data were collected from employment records and administrative files. Analysis was by multiple logistic regression. Significant associations were found between sick leave and nurse-patient ratio among head nurses, patient's duration of stay, and one hospital. Sick leave was more frequent among full time permanent nurses and among those on night and evening schedules. These associations were independent of age, duration of service in this hospital or in the actual job assignment, and care unit. This study supports the relevance of using sick leave as a non-specific indicator of health out-comes.

Certified sick leave and work load. A case referent study among nurses

A case-referent study assessed the association of medically certified sick leave from work with some occupational characteristics: hospital, care unit, and two work-load indices (patients' average length-of-stay, and nurse-patient ratio). Study participants were nurses from seven general hospitals in Quebec City, who had been employed for at least 6 months at the time of study. Cases (n = 1165) experienced at least one episode of medically certified sick leave between January 1, 1984 and May 31, 1987. Referents (n = 1165) were chosen from subjects who had no such leave and were matched to cases on the basis of dates on which sick leave occurred. Occupational data were collected from employment records and administrative files. Analysis was conducted using multiple logistic regression. Statistically significant associations were found between sick leave and one hospital, two care units, and nurse-patient ratio among head nurses. These odds ratios were independent of length of service in the hospital or in the actual job assignment. The study supports the pertinence of using certified sick leave as a nonspecific indicator of health outcomes.

Oxidation of non-phenolic substrates. An expanded role for laccase in lignin biodegradation

In the presence of substrates such as Remazol Blue and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulphonate) (ABTS), laccases Coriolus (Trametes) versicolor can also oxidize non-phenolic lignin model compounds. Veratryl alcohol (I) and 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-propane-1,3-diol (III) were oxidized by laccase and mediator to give the alpha-carbonyl derivatives. The beta-1 lignin model dimer, 1-(3,4-dimethoxyphenyl)-2-phenoxy-ethane-1,2-diol (II) was cleaved by laccase in the presence of ABTS to give veratraldehyde and benzaldehyde. On the basis of these observations, we propose that laccase is capable of oxidizing both phenolic and non-phenolic moieties of lignin but that the latter is dependent on the co-presence of primary laccase substrates.

Veratryl alcohol oxidases from the lignin-degrading basidiomycete Pleurotus sajor-caju

The basidiomycete Pleurotus sajor-caju mineralizes ring-14C-labelled lignin (dehydrogenative polymer) when grown in mycological broth. Under these conditions, two veratryl alcohol oxidase (VAO) enzymes were found in the culture medium. They oxidized a number of aromatic alcohols to aldehydes and reduced O2 to H2O2. The enzymes were purified by ion-exchange and gel-permeation chromatography. The final step of purification on Mono Q resolved the activity into two peaks (VAO I and VAO II). Both enzymes had the same Mr, approx. 71,000, but their isoelectric points differed slightly, 3.8 for VAO I and 4.0 for VAO II. Their amino acid compositions were similar except for aspartic acid/asparagine and glycine. Both enzymes are glycoproteins and contain flavin prosthetic groups. Their pH optima were around 5, and kinetic constants and specificities were similar. 4-Methoxybenzyl alcohol was oxidized the most rapidly, followed by veratryl alcohol. Not all aromatic alcohols were oxidized, neither were non-aromatic alcohols. Cinnamyl alcohol was oxidized at the gamma position. The VAO enzymes thus represent a significantly different route for veratryl alcohol oxidation from that catalysed by the previously found lignin peroxidases from Phanerochaete chrysosporium. The role of the oxidases in biodegradation might be to produce H2O2 during oxidation of lignin fragments.

Validity of self reported work history

Many epidemiological studies of the relation between work and disease use information on work history obtained by interview from the study subjects. A validation study was undertaken to evaluate the accuracy of this information collected from 100 workers in a shipbuilding industry. The information furnished by the workers was compared with that present in the company's registers. The work history (job titles and starting dates) was relatively accurate and the validity varied with the number of events to declare and with their duration; it also depended on the type of information and the precision required.

[The organization of work in hospitals and its effect on nurses health.]

This article covers the actual knowledge on the organization of infirmary work and its effects on nurses' physical and mental health. Then it proposes a conceptual model to study the question. This model is concerned with the relationship between the work load, a potential source of health problems and the autonomy and the social support which may relieve the load or its effects.

Simultaneous measurement of serum 25-hydroxycholecalciferol and 25-hydroxyergocalciferol

A method for the selective measurement of serum 25-hydroxycholecalciferol and 25-hydroxyergocalciferol has been developed. The two hydroxysecosteroids were measured in a control group and in a group of ambulatory patients treated chronically with anticonvulsant drugs. In both groups the serum levels of 25-hydroxycholecalciferol and 25-hydroxyergocalciferol followed a log normal distribution. No significant difference could be elicited between the control and the treated groups for either hydroxysecosteroid. Furthermore the data shows how important is the dietary source of vitamin D in our environment.

Australia antigen 'ad' and 'ay' subtypes. Purification and partial characterization

The two commonly-found Australia antigen subtypes have been purified by simple inexpensive, reproducible, physico-chemical methods involving ammonium sulfate precipitation, peptic digestion, calcium phosphate gel fractionation and molecular sieving on Sepharose 4B. The overall recovery of the two subtypes varied between 50 and 60% of the total antigen content on the starting serum. The purified antigens were found homogeneous by discontinuous gel electrophoresis, analytical ultracentrifugation, and isopycnic banding ultracentrifugation. No contaminating serum proteins could be detected by immunoelectrophoresis. The two purified antigen subtypes have similar Stokes radii and buoyant densities. The sedimentation coefficients for the 'ad' and 'ay' subtypes were found to be 33.0 and 40.1 times 10- minus 13 sec, respectively.