Two alternative job stress models and the risk of coronary heart disease

OBJECTIVES

This study examined the association between two alternative job stress models-the effort-reward imbalance model and the job strain model-and the risk of coronary heart disease among male and female British civil servants.

METHODS

The logistic regression analyses were based on a prospective cohort study (Whitehall II study) comprising 6895 men and 3413 women aged 35 to 55 years. Baseline measures of both job stress models were related to new reports of coronary heart disease over a mean 5.3 years of follow-up.

RESULTS

The imbalance between personal efforts (competitiveness, work-related overcommitment, and hostility) and rewards (poor promotion prospects and a blocked career') was associated with a 2.15-fold higher risk of new coronary heart disease. Job strain and high job demands were not related to coronary heart disease; however, low job control was strongly associated with new disease. The odds ratios for low job control were 2.38 and 1.56 for self-reported and externally assessed job control, respectively. Work characteristics were simultaneously adjusted and controlled for employment grade level, negative affectivity, and coronary risk factors.

CONCLUSIONS

This is apparently the first report showing independent effects of components of two alternative job stress models-the effort-reward imbalance model and the job strain model (job control only)-on coronary heart disease.

Hydroxylation of chlorzoxazone as a specific probe for human liver cytochrome P-450IIE1

Human cytochrome P-450IIE1 has been implicated in the oxidation of a number of substrates, including protoxins and -carcinogens. To date, no drugs have been identified that are exclusive substrates for the protein and are applicable for use as noninvasive probes of the in vivo function of the enzyme in humans. Chlorzoxazone was found to be oxidized only to 6-hydroxychlorzoxazone in human liver microsomes. Results of steady-state kinetics are consistent with the view that only a single enzyme catalyzes the reaction. The microsomal reaction was strongly inhibited by rabbit anti-P-450IIE1 and, in a competitive manner, by known P-450IIE1 substrates. Rates of chlorzoxazone 6-hydroxylation in different human liver microsomal preparations were well correlated with levels of immunochemically measured P-450IIE1 and rates of (CH3)2NNO oxidation. Chlorzoxazone 6-hydroxylation was also found to be catalyzed by purified human liver P-450IIE1. These results provide strong evidence that P-450IIE1 is the primary catalyst of chlorzoxazone 6-hydroxylation in human liver. Rates of chlorzoxazone 6-hydroxylation vary considerably among human liver samples, and chlorzoxazone 6-hydroxylation may have potential use as a noninvasive probe in estimating the in vivo expression of human P-450IIE1 and its significance as a risk factor in the toxicity and carcinogenicity of a number of solvents, nitrosamines, and drugs.

An Update on Current Therapeutic Drugs Treating COVID-19

The current pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has presented unprecedented challenges to the healthcare systems in almost every country around the world. Currently, there are no proven effective vaccines or therapeutic agents against the virus. Current clinical management includes infection prevention and control measures and supportive care including supplemental oxygen and mechanical ventilatory support. Evolving research and clinical data regarding the virologic SARS-CoV-2 suggest a potential list of repurposed drugs with appropriate pharmacological effects and therapeutic efficacies in treating COVID-19 patients. In this review, we will update and summarize the most common and plausible drugs for the treatment of COVID-19 patients. These drugs and therapeutic agents include antiviral agents (remdesivir, hydroxychloroquine, chloroquine, lopinavir, umifenovir, favipiravir, and oseltamivir), and supporting agents (Ascorbic acid, Azithromycin, Corticosteroids, Nitric oxide, IL-6 antagonists), among others. We hope that this review will provide useful and most updated therapeutic drugs to prevent, control, and treat COVID-19 patients until the approval of vaccines and specific drugs targeting SARS-CoV-2.

Job strain, effort-reward imbalance and employee well-being: a large-scale cross-sectional study

This study investigated the effects of the Job Demand-Control (JD-C) Model and the Effort-Reward Imbalance (ERI) Model on employee well-being. A cross-sectional survey was conducted comprising a large representative sample of 11,636 employed Dutch men and women. Logistic regression analyses were used. Controlling for job sector, demographic characteristics (including educational level) and managerial position, employees reporting high job demands (i.e. psychological and physical demands) and low job control had elevated risks of emotional exhaustion, psychosomatic and physical health complaints and job dissatisfaction (odds ratios ranged from 2.89 to 10.94). Odds ratios were generally higher in employees reporting both high (psychological and physical) efforts and low rewards (i.e. poor salary, job insecurity and low work support): they ranged from 3.23 to 15.43. Furthermore, overcommitted people had higher risks of poor well-being due to a high effort-low reward mismatch (ORs: 3.57-20.81) than their less committed counterparts (ORs: 3.01-12.71). Finally, high efforts and low occupational rewards were stronger predictors of poor well-being than low job control when both job stress models were simultaneously adjusted. In conclusion, our findings show independent cumulative effects of both the JD-C Model and the ERI Model on employee well-being and are not significantly different in men and women as well as in young and old people. In particular, high (psychological and physical) efforts and low rewards adversely affected employee well-being. Preliminary findings also indicate excess risks of poor well-being in overcommitted persons suffering from high cost--low gain conditions at work.

Low status control, high effort at work and ischemic heart disease: prospective evidence from blue-collar men

An inverse relation between socio-economic class and occurrence of ischemic heart disease (IHD) in advanced societies is an often replicated finding from empirical studies. Yet, the processes which produce these effects remain an open question. One promising explanation concerns the prevalence of stressful working life, especially of distinct 'job strain' occupations. Based on these considerations, we develop a refined concept of work-related socio-emotional distress which considers a mismatch between high workload and low control over occupational status (e.g. job insecurity, poor promotion prospects, status inconsistency) as crucial distress-provoking conditions. Moreover, we assume that the effect of this condition on IHD risk is substantially increased by the presence of a distinct individual pattern of coping with work demand ('need for control'). Based on data from a 6.5 years prospective study on IHD incidence (n = 21) in a cohort of 416 middle-aged blue-collar men this concept is tested using logistic regression analysis. Results indicate that status inconsistency [multivariate odds ratio (o.r.): 4.4], job insecurity (o.r. 3.4), work pressure (o.r. 3,4) and 'need for control' (o.r. 4,5) independently predict IHD occurrence after adjusting for major confounding somatic and behavioral coronary risk factors. In conclusion, a refined model of work-related socio-emotional distress substantially contributes to the explanation of high IHD incidence among blue-collar men.

Isoform specificity of trimethylamine N-oxygenation by human flavin-containing monooxygenase (FMO) and P450 enzymes: selective catalysis by FMO3

In the present study, we expressed human flavin-containing monooxygenase 1 (FMO1), FMO3, FMO4t (truncated), and FMO5 in the baculovirus expression vector system at levels of 0.6 to 2.4 nmol FMO/mg of membrane protein. These four isoforms, as well as purified rabbit FMO2, and eleven heterologously expressed human P450 isoforms were examined for their capacity to metabolize trimethylamine (TMA) to its N-oxide (TMAO), using a new, specific HPLC method with radiochemical detection. Human FMO3 was by far the most active isoform, exhibiting a turnover number of 30 nmol TMAO/nmol FMO3/min at pH 7.4 and 0.5 mM TMA. None of the other monooxygenases formed TMAO at rates greater than 1 nmol/nmol FMO/min under these conditions. Human fetal liver, adult liver, kidney and intestine microsomes were screened for TMA oxidation, and only human adult liver microsomes provided substantial TMAO-formation (range 2.9 to 9.1 nmol TMAO/mg protein/min, N = 5). Kinetic studies of TMAO formation by recombinant human FMO3, employing three different analytical methods, resulted in a Km of 28 +/- 1 microM and a Vmax of 36.3 +/- 5.7 nmol TMAO/nmol FMO3/min. The Km determined in human liver microsomes ranged from 13.0 to 54.8 microM. Therefore, at physiological pH, human FMO3 is a very specific and efficient TMA N-oxygenase, and is likely responsible for the metabolic clearance of TMA in vivo in humans. In addition, this specificity provides a good in vitro probe for the determination of FMO3-mediated activity in human tissues, by analyzing TMAO formation at pH 7.4 with TMA concentrations not higher than 0.5 mM.

Psychosocial work environment and myocardial infarction: improving risk estimation by combining two complementary job stress models in the SHEEP Study

OBJECTIVES

Associations between two alternative formulations of job stress derived from the effort-reward imbalance and the job strain model and first non-fatal acute myocardial infarction were studied. Whereas the job strain model concentrates on situational (extrinsic) characteristics the effort-reward imbalance model analyses distinct person (intrinsic) characteristics in addition to situational ones. In view of these conceptual differences the hypothesis was tested that combining information from the two models improves the risk estimation of acute myocardial infarction.

METHODS

951 male and female myocardial infarction cases and 1147 referents aged 45-64 years of The Stockholm Heart Epidemiology (SHEEP) case-control study underwent a clinical examination. Information on job stress and health adverse behaviours was derived from standardised questionnaires.

RESULTS

Multivariate analysis showed moderately increased odds ratios for either model. Yet, with respect to the effort-reward imbalance model gender specific effects were found: in men the extrinsic component contributed to risk estimation, whereas this was the case with the intrinsic component in women. Controlling each job stress model for the other in order to test the independent effect of either approach did not show systematically increased odds ratios. An improved estimation of acute myocardial infarction risk resulted from combining information from the two models by defining groups characterised by simultaneous exposure to effort-reward imbalance and job strain (men: odds ratio 2.02 (95% confidence intervals (CI) 1.34 to 3.07); women odds ratio 2.19 (95% CI 1.11 to 4.28)).

CONCLUSIONS

Findings show an improved risk estimation of acute myocardial infarction by combining information from the two job stress models under study. Moreover, gender specific effects of the two components of the effort-reward imbalance model were observed.

High effort, low reward, and cardiovascular risk factors in employed Swedish men and women: baseline results from the WOLF Study

STUDY OBJECTIVE

To examine associations between measures of work stress (that is, the combination of high effort and low reward) and cardiovascular risk factors.

DESIGN

Cross sectional first screening of a prospective cohort study.

SETTING AND PARTICIPANTS

The study was conducted among 5720 healthy employed men and women living in the greater Stockholm area aged 19-70 years. All analyses were restricted to subjects with complete data (n = 4958). The investigation of associations between indicators of effort-reward imbalance and cardiovascular risk factors was restricted to the age group 30-55 years (n = 3427).

MAIN RESULTS

Subjects reporting high effort and low reward at work had a higher prevalence of well known risk factors for coronary heart disease. After adjustment for relevant confounders, associations between a measure of extrinsic effort and reward (the effort-reward ratio) and hypertension (multivariate prevalence odds ratio (POR) 1.62-1.68), increased total cholesterol (upper tertile 220 mg/dl)(POR = 1.24) and the total cholesterol/high density lipoprotein(HDL)-cholesterol ratio (upper tertile 4.61)(POR 1.26-1.30) were found among men. Among women a measure of high intrinsic effort (immersion) was related to increased low density lipoprotein (LDL)-cholesterol (upper tertile 130 mg/dl)(POR 1.37-1.39). Analyses of variance showed increasing mean values of LDL cholesterol with an increasing degree of the effort-reward ratio among men and increased LDL-cholesterol among women with high levels of intrinsic effort (upper tertile of immersion).

CONCLUSIONS

Findings lend support to the hypothesis that effort-reward imbalance represents a specific constellation of stressful experience at work related to cardiovascular risk. The relation was not explained by relevant confounders (for example, lack of physical exercise, body weight, cigarette smoking).

Oxidation of acetaminophen to its toxic quinone imine and nontoxic catechol metabolites by baculovirus-expressed and purified human cytochromes P450 2E1 and 2A6

Acetaminophen (APAP), a widely used analgesic and antipyretic agent, is bioactivated by cytochromes P450 to cause severe hepatotoxicity. APAP is oxidized by two pathways to form a toxic intermediate, N-acetyl-p-benzoquinone imine (NAPQI), and a nontoxic catechol metabolite, 3-hydroxy-APAP (3-OH-APAP). We investigated the role of P450 2E1 and 2A6 in APAP oxidation by using baculovirus-expressed and highly purified forms of human P450 2E1 and 2A6. An electrochemical HPLC assay was developed to quantify both oxidative metabolites simultaneously. For the first time, it was demonstrated that human P450 2E1 selectively oxidized APAP to NAPQI (assayed as its glutathione conjugate, GS-APAP), whereas human P450 2A6 selectively oxidized APAP to 3-OH-APAP. At 1 mM APAP, the relative ratio for the formation of GS-APAP vs 3-OH-APAP with human P450 2E1 was approximately 6:1, whereas the ratio with human P450 2A6 was 1:3. Apparent Km and Vmax values for the formation of GS-APAP by human P450 2E1 were 1.3 mM and 6.9 nmol/min/nmol of P450, respectively, whereas they were 4.6 mM and 7.9 nmol/min/nmol of P450 for P450 2A6. Apparent Km and Vmax values for the formation of 3-OH-APAP by human P450 2E1 were 4.0 mM and 2.5 nmol/min/nmol of P450, respectively, whereas they were 2.2 mM and 14.2 nmol/min/nmol of P450, respectively, for P450 2A6. Thus, although at toxic doses of APAP P450 2E1 is the more efficient catalyst for the formation of the toxic metabolite NAPQI, P450 2A6 also can contribute significantly to NAPQI production.

Human cytochrome P450 2E1 is a major autoantigen associated with halothane hepatitis

Autoantibodies against specific human cytochrome P450s have been found in the sera of patients suffering from a variety of diseases, including those caused by drugs. In the cases of tienilic acid- and dihydralazine-induced hepatitis, patients have serum autoantibodies directed against cytochromes P450 2C9 and P450 1A2, respectively. In the present study, we have found that 25 of 56 (45%) patients diagnosed with halothane hepatitis have autoantibodies that react with human cytochrome P450 2E1 that was purified from a baculovirus expression system. The autoantibodies inhibited the activity of cytochrome P450 2E1 and appeared to be directed against mainly conformational epitopes. In addition, because cytochrome P450 2E1 became trifluoroacetylated when it oxidatively metabolized halothane, it is possible that the covalently altered form of cytochrome P450 2E1 may be able to bypass the immunologic tolerance that normally exists against cytochrome P450 2E1. A similar mechanism may explain the formation of autoantibodies that have been found against other cellular targets of the reactive trifluoroacetyl chloride metabolite of halothane.

Pulsatile non-Newtonian blood flow simulation through a bifurcation with an aneurysm

Blood flow is analysed by means of computer simulation in an idealized arterial bifurcation model which is pathologically altered by a saccular aneurysm. The theoretical study of the flow pattern and the paths of fluid particles is carried out under pulsatile Newtonian and non-Newtonian flow conditions. The governing equations are solved numerically with the use of the finite element method. The results show the disturbed blood flow in the bifurcation and the relatively low intra-aneurysmal flow circulation. In addition to the study of basic flow patterns in the segment, a comparison of non-Newtonian and Newtonian results is carried out. This comparison proves that for the considered large artery model under physiological flow conditions where the yield number is relatively low there is no essential difference in the results.

Thyroid dysfunction in patients with diabetes: clinical implications and screening strategies

BACKGROUND

Patients with diabetes mellitus are at an increased risk of thyroid disease. The frequency of thyroid dysfunction in diabetic patients is higher than that of the general population and up to a third of patients with type-1 diabetes (T1DM) ultimately develop thyroid dysfunction. Unrecognised thyroid dysfunction may impair metabolic control and add to cardiovascular disease risk in diabetic patients.

AIMS

Our aims were to review the current literature on the association between thyroid dysfunction and diabetes mellitus, to highlight relevant clinical implications, and to examine present thyroid disease screening strategies in routine diabetes care.

RESULTS

The pleiotropic effects of thyroid hormones on various metabolic processes are now better understood. Uncontrolled hyperthyroidism in diabetic patients may trigger hyperglycaemic emergencies while recurrent hypoglycaemic episodes have been reported in diabetic patients with hypothyroidism. Furthermore, thyroid dysfunction may amplify cardiovascular disease risk in diabetic patients through inter-relationships with dyslipidaemia, insulin resistance and vascular endothelial dysfunction. However, the significance of subclinical degrees of thyroid dysfunction remains to be clarified. While these developments have implications for diabetic patients a consensus is yet to be reached on optimal thyroid screening strategies in diabetes management.

CONCLUSIONS

The increased frequency of thyroid dysfunction in diabetic patients and its likely deleterious effects on cardiovascular and metabolic function calls for a systematic approach to thyroid disease screening in diabetes. Routine annual thyroid testing should be targeted at diabetic patients at risk of thyroid dysfunction such as patients with T1DM, positive thyroid autoantibodies or high-normal TSH concentrations.

Chronic work stress, sickness absence, and hypertension in middle managers: general or specific sociological explanations?

The issue of differential prediction of health outcomes by sociological models of work stress has received little attention so far. This paper argues, both on theoretical and empirical grounds, that active coping with the experience of chronic work stress is more likely to be associated with physical health consequences of sustained autonomic arousal such as hypertension, whereas passive coping may predispose individuals to withdrawal behavior such as sickness absence from work. Based on data from a cross-sectional study on 189 male middle-aged (40-55, 48.3 +/- 4.6 years) middle managers in a car-producing company in Germany, this hypothesis is tested in the framework of the theoretical model of effort-reward imbalance at work. More specifically, the simultaneous manifestation of high effort and low reward at work, indicative of active coping, is expected to statistically predict the risk of being hypertensive. Conversely, suffering from low occupational rewards in the absence of signs of sustained effort, indicative of passive coping, is expected to predict sickness absence (SA) behavior. Multivariate odds ratios (OR) derived from logistic regression analysis and adjusted for important confounders indicate that three measures of low reward are associated with short-term SA (OR ranging from 3.30 to 9.15), that one measure of low reward is associated with long-term SA (OR: 2.67) and that two measures of low reward are associated with number of SA episodes (OR 4.05 and 6.33), whereas no indicator of high effort at work is significantly associated with SA. On the other hand, the OR of being hypertensive is 5.77 in middle managers who suffer from high effort and low reward simultaneously. In conclusion, a sociological model of work stress which allows for differential prediction of health outcomes according to the important notions of active versus passive coping with work demands finds preliminary empirical support.

Vascular activation of adhesion molecule mRNA and cell surface expression by ionizing radiation

During cutaneous inflammatory reactions the recruitment of circulating leukocytes into the tissue critically depends on the regulated expression of endothelial cell adhesion molecules (CAMs). Various proinflammatory stimuli upregulate endothelial CAMs, including cytokines and UV irradiation. We have investigated the effects of ionizing radiation (IR) on endothelial CAM expression. Organ cultures of normal human skin as well as cultured human dermal microvascular endothelial cells (HDMEC) were exposed to IR. Expression of three major endothelial CAMs was studied in skin organ cultures by immunohistochemistry and in cell culture by Northern blot analysis and flow cytometry. In skin organ cultures vascular immunoreactivity for ICAM-1, E-selectin, and VCAM-1 was strongly induced 24 h after exposure to 5 or 10 Gy of IR, while immunoreactivity for CD31/PECAM-1, a constitutively expressed endothelial cell adhesion molecule, remained unchanged. In cultured HDMEC IR upregulated ICAM-1, VCAM-1, and E-selectin mRNAs and cell surface expression in a time- and dose-dependent fashion. Cellular morphology and viability remained unaltered by IR up to 24 h postirradiation. This study characterizes microvascular activation of adhesion molecule expression in response to ionizing radiation in a clinically relevant IR dose range. The findings also underscore the ability of endothelial cells to integrate environmental electromagnetic stimuli.

Chronic work stress is associated with atherogenic lipids and elevated fibrinogen in middle-aged men

OBJECTIVES

To examine the association between a model of chronic work stress (high efforts in combination with low rewards) and two risk factors of coronary heart disease, low-density-lipoprotein (LDL)-cholesterol and fibrinogen.

DESIGN

A cross-sectional study in a group of 179 healthy middle-aged (48.5 +/- 4.5) male middle managers.

SETTING

A large car-producing enterprise in Germany.

RESULTS

After adjustment for relevant covariates, logistic regression analysis showed independent effects of a composite measure of high effort and low reward at work on the prevalence of elevated (upper tertile, i.e. > or = 160 mg dL-1) LDL-cholesterol (prevalence odds ratio (POR) = 3.57; 95% confidence intervals (CI): 1.24-10.20) and on elevated (upper quintile, i.e. > or = 420 mg dL-1) plasma fibrinogen (POR = 6.71 (CI: 1.57-28.76). Apart from this core measure, cigarette smoking, overweight and alcohol consumption were the covariates with the relatively strongest contributions to the multivariate model.

CONCLUSIONS

Results give preliminary evidence on an independent association of chronic work stress with atherogenic lipids and with elevated fibrinogen in an occupationally homogeneous group of healthy middle-aged men.

Interleukin (IL)-6 and its soluble receptor induce TIMP-1 expression in synoviocytes and chondrocytes, and block IL-1-induced collagenolytic activity

To define the potential role of interleukin-6 (IL-6) and its soluble receptor alpha in cartilage metabolism, we analyzed their effects on tissue inhibitor of metalloproteases (TIMP) synthesis by synoviocytes and chondrocytes. TIMP-1 production by isolated human articular synovial fibroblasts and chondrocytes, stimulated by IL-6 and/or its soluble receptor, was first assayed by specific enzyme-linked immunosorbent assay; the slight stimulatory effect of IL-6 on TIMP-1 production by both types of cells was markedly amplified by the addition of soluble receptor, the maximal secretion being observed only at 96 h. TIMP-1 mRNA expression, determined by ribonuclease protection assay, was induced by IL-6 together with its soluble receptor, but TIMP-2 and -3 mRNAs were not affected by these factors. A specific neutralizing antibody abolished the effects of the soluble receptor. Finally, supernatant from synoviocytes stimulated by IL-6 plus its soluble receptor blocked almost completely the collagenolytic activity of supernatant from IL-1-induced synoviocytes. These observations indicate that IL-6 and its soluble receptor have a protective role in the metabolism of cartilage. Given the high levels of soluble receptor in synovial fluid and the marked induction of IL-6 by IL-1 or TNF-alpha, it is likely that IL-6 and its soluble receptor are critical in controlling the catabolic effects of pro-inflammatory cytokines.

Electrospray ionization mass spectrometric analysis of intact cytochrome P450: identification of tienilic acid adducts to P450 2C9

A general scheme for the purification of baculovirus-expressed cytochrome P450s (P450s) from the crude insect cell pastes has been designed which renders the P450s suitable for analysis by high-performance liquid chromatography (HPLC) electrospray ionization mass spectrometry (ESI-MS). An HPLC/ESI-MS procedure has been developed to analyze small amounts of intact purified P450 (P450s cam-HT, 1A1, 1A2, 2A6, 2B1, 2C9, 2C9 C175R, 3A4, 3A4-HT) and rat NADPH cytochrome P450 reductase (P450 reductase). The experimentally determined and predicted (based on the amino acid sequences) molecular masses (MMs) of the various proteins had identical rank orders. For each individual protein, the difference between the experimentally determined (+/-SD, based on experiments performed on at least 3 different days) and predicted MMs ranged from 0.002 to 0.035%. Each experimentally determined MM had a standard deviation of less than 0.09% (based on the charge state distribution). Application of this HPLC/ESI-MS technique made the detection of the covalent modification to P450 2C9 following mechanism-based inactivation by tienilic acid possible. In the absence of glutathione, three P450 2C9 species were detected that produced ESI mass spectra corresponding to native P450 2C9 and both a monoadduct and a diadduct of tienilic acid to P450 2C9. In the presence of glutathione, only native P450 2C9 and the monoadduct were detected. Based on the observed mass shifts for the P450 2C9/tienilic acid adducts, a mechanism for the inactivation of P450 2C9 by tienilic acid is proposed.

Income, occupational position, qualification and health inequalities--competing risks? (comparing indicators of social status)

STUDY OBJECTIVE

The debate on health inequalities has shifted from the consequences of occupational position, as expressed in the Registrar General's classification, to consequences of material living conditions. This change in interest occurred without comparative analyses of different sources of health inequalities. Thus this study investigated the relative contribution of "material resources" (income), "qualification" and "occupational position" for explaining social differentials in mortality.

DESIGN AND SETTING

Analyses were performed with records from a statutory health insurance in West Germany. The analyses were performed with data of 84,814 employed men and women between 25 and 65 years of age who were insured between 1987 and 1995 for at least 150 days.

RESULTS

The three indicators were statistically associated, but not strong enough to warrant the conclusion that they share the same empirical content. The relative risk (hazard rate) for income by controlling for occupational position and gender for the highest as compared with the lowest category was 1.99 (95% CI 1.66, 2.39). The corresponding relative risk for income by controlling for qualification and gender was 2.03 (95% CI 1.68, 2.46). In both multivariate analyses, the effects of occupational position and qualification were no longer interpretable because of large confidence intervals. In sum, income related relative mortality risks were the comparably highest, while qualification and occupational position were no longer substantial.

CONCLUSIONS

The results emphasise the present discussion on the consequences of material living conditions. Income on the one hand and qualification and occupational position on the other are largely independent. Mortality related effects of income override those of the other socioeconomic status indicators. However, seen in a time perspective, qualification may still have a placement function at least for the first occupational position.

Epidemic of liver disease caused by hydrochlorofluorocarbons used as ozone-sparing substitutes of chlorofluorocarbons

BACKGROUND

Hydrochlorofluorocarbons (HCFCs) are used increasingly in industry as substitutes for ozone-depleting chlorofluorocarbons (CFCs). Limited studies in animals indicate potential hepatotoxicity of some of these compounds. We investigated an epidemic of liver disease in nine industrial workers who had had repeated accidental exposure to a mixture of 1,1-dichloro-2,2,2-trifluoroethane (HCFC 123) and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC 124). All nine exposed workers were affected to various degrees. Both compounds are metabolised in the same way as 1-bromo-1-chloro-2,2,2-trifluoroethane (halothane) to form reactive trifluoroacetyl halide intermediates, which have been implicated in the hepatotoxicity of halothane. We aimed to test whether HCFCs 123 and 124 can result in serious liver disease.

METHODS

For one severely affected worker liver biopsy and immunohistochemical stainings for the presence of trifluoroacetyl protein adducts were done. The serum of six affected workers and five controls was tested for autoantibodies that react with human liver cytochrome-P450 2E1 (P450 2E1) and P58 protein disulphide isomerase isoform (P58).

FINDINGS

The liver biopsy sample showed hepatocellular necrosis which was prominent in perivenular zone three and extended focally from portal tracts to portal tracts and centrilobular areas (bridging necrosis). Trifluoroacetyl-adducted proteins were detected in surviving hepatocytes. Autoantibodies against P450 2E1 or P58, previously associated with halothane hepatitis, were detected in the serum of five affected workers.

INTERPRETATION

Repeated exposure of human beings to HCFCs 123 and 124 can result in serious liver injury in a large proportion of the exposed population. Although the exact mechanism of hepatotoxicity of these agents is not known, the results suggest that trifluoroacetyl-altered liver proteins are involved. In view of the potentially widespread use of these compounds, there is an urgent need to develop safer alternatives.

Accuracy and interobserver variability of coronary cineangiography: a comparison with postmortem evaluation

The accuracy of interpretation of coronary cineangiography by two independent observers was tested against postmortem findings in 27 patients who died within 6 months of cardiac catheterization. Variations in cineangiographic interpretations between the angiographers were also evaluated. Two patients had normal coronary arteries, while the remaining 25 patients had significant coronary artery disease. Significant stenosis was defined as 75% or greater reduction in luminal diameter. Of 326 coronary segments that could be evaluated postmortem, 15% could not be evaluated cineangiographically. The respective overall accuracy of the two observers was 89 and 88% with an accuracy of 96 and 100% for the left main coronary artery, 91 and 93% for the left anterior descending artery, 84 and 86% for the right coronary artery and 89 and 79% for the left circumflex coronary artery. Cineangiographic assessment of luminal status distal to a significant proximal lesion was possible in more than 70% of major vessels with accuracy levels of 86% for both observers. Of 96 distal vessels inadequately opacified cineangiographically, 49 (52%) were found to be free of significant lesions. Both angiographers agreed in their assessment of 86% of the 340 coronary segments. Interobserver agreement was significantly better for the left main, right and left anterior descending coronary arteries than for the left circumflex coronary artery (p less than 0.05). Accuracy was 93% for 244 segments that were adequately opacified and assessed the same by both angiographers. Cineangiography can thus be used to evaluate coronary anatomy with a high degree of accuracy and minimal interobserver variability.

Fractures of the calcaneum

We have assessed the long-term results after operative and non-operative treatment of undisplaced and displaced calcaneal fractures.

At a mean of 6.5 years, we reviewed 70 patients with a calcaneal fracture who were divided into four groups: group 1, 18 patients with undisplaced fractures and a normal Böhler’s angle (BA) who had been treated non-operatively; group 2, 23 with intra-articular fractures and a BA < 10° who had been treated non-operatively; group 3, 13 with intra-articular fractures and a BA > 10° who had been treated surgically; and group 4, 16 with intra-articular fractures and a BA < 10° who had been treated surgically.

The results were assessed by a clinical score considering pain, return to work, return to physical activity, change in shoe-wear and the requirement for subtalar arthrodesis.

Patients with undisplaced calcaneal fractures had a good outcome. Those with displaced fractures treated surgically who presented at follow-up with a BA > 10° had a satisfactory functional outcome and those with displaced fractures who had non-operative treatment had a poor outcome. The poorest outcome was consistently seen in patients who were treated operatively without restoration of BA. Open reduction and internal fixation of intra-articular calcaneal fractures can only be expected to benefit those patients in whom nearly anatomical reconstruction is obtained.

Does a stressful psychosocial work environment mediate the effects of shift work on cardiovascular risk factors?

OBJECTIVES

Associations between shift work, chronic psychosocial work stress, and 2 important cardiovascular risk factors, hypertension and atherogenic lipids were studied. The hypothesis was tested that psychosocial work stress, as defined by the model of effort-reward imbalance, mediates the effects of shift work on cardiovascular risk.

METHODS

Altogether 2288 male participants aged 30-55 years in the baseline screening of the Swedish WOLF (work organization, lipids, and fibrinogen) study underwent a clinical examination and answered a standardized questionnaire measuring shiftwork schedules, effort-reward imbalance at work, and health-adverse behavior.

RESULTS

In addition to the direct effects of shift work on cardiovascular risk, mediating effects of effort-reward imbalance at work were found. The respective odds ratios (OR) ranged from 2.18 to 2.27 for hypertension and from 1.34 to 1.45 for atherogenic lipids. While the effects remained significant after extensive confounder control concerning hypertension, part of the observed effect on atherogenic lipids was due to behavioral influences.

CONCLUSIONS

Despite obvious limitations, the results indicated that a stressful psychosocial work environment acts as a mediator of health-adverse effects of shift work on hypertension and, partly, atherogenic lipids. In terms of occupational health the findings call for a more comprehensive assessment of the health risks associated with shift work.

Psychosocial work environment and the risk of coronary heart disease

OBJECTIVES

Remarkable changes in the working situation have led to the increasing importance of psychomentally and socio-emotionally demanding conditions at work. With the help of theoretical models, those highly prevalent psychosocial work environments were conceptualized which influence the risk of coronary heart disease by enhanced activation of the autonomic nervous system. One of the most prominent theoretical approaches, the job strain model, and a more recent approach, the effort-reward imbalance model, are discussed in the paper.

EMPIRICAL EVIDENCE

Findings from prospective and cross-sectional studies indicate that job strain and effort-reward imbalance at work define specific conditions of chronic work stress that are associated with an elevated risk of coronary heart disease (CHD). Respective multivariate odds-ratios range from 1.2 to 5.0 with respect to job strain, and from 1.5 to 6.1 with respect to effort-reward imbalance. These associations are explained neither by established behavioral or biomedical risk factors nor by physical and chemical hazards at work, rather they define independent, new work-related risk conditions. There is additional evidence that effort-reward imbalance may mediate the association of some traditional occupational exposures, such as shift work, with cardiovascular risk: in a cross-sectional study, prevalence odds ratios of hypertension and atherogenic lipids attributable to effort-reward imbalance were relatively highest among shiftworkers as compared to daytime workers. Preliminary results from intervention programs based on the theoretical models document favorable effects on health.

CONCLUSIONS

Information derived from theoretical models on psychosocial work environment may help to better identify populations at risk and to develop and apply specific, theory-guided preventive activities in the future.

In vitro activity of aplidine, a new marine-derived anti-cancer compound, on freshly explanted clonogenic human tumour cells and haematopoietic precursor cells

Aplidine is a new marine anti-cancer depsipeptide isolated from the Mediterranean tunicate Aplidium albicans. We have evaluated its antiproliferative action against a variety of freshly explanted human tumour specimens. Concentration ranges of 0.01-1.0 microM and 0.0001-1.0 microM were used in short- and long-term exposure schedules respectively. After exposure for 1 h in 49 evaluable specimens, aplidine showed a clear concentration-dependent anti-tumour effect. At 0.05 microM, 85% of the specimens were markedly inhibited. Continuous exposure for 21-28 days in 54 tumour specimens also led to a concentration-dependent activity relationship. Fifty per cent and 100% tumour inhibitions were achieved with 0.001 microM and 0.05 microM respectively. A head to head evaluation assessing short vs continuous exposure was carried out, resulting in evidence of an activity-time of exposure relationship. Breast, melanoma and non-small-cell lung cancer appear to be sensitive to low concentrations of aplidine. In addition the evaluation of the effects of aplidine on haematopoietic cells showed a concentration-dependent toxicity. However, under continuous exposure, active concentrations induced mild bone marrow toxicity, indicating that a therapeutic window at marginally myelotoxic concentrations might exist.

Epigenetics/epigenomics and prevention by curcumin of early stages of inflammatory-driven colon cancer

Colorectal cancer (CRC) is associated with significant morbidity and mortality in the US and worldwide. CRC is the second most common cancer-related death in both men and women globally. Chronic inflammation has been identified as one of the major risk factors of CRC. It may drive genetic and epigenetic/epigenomic alterations, such as DNA methylation, histone modification, and non-coding RNA regulation. Current prevention modalities for CRC are limited and some treatment regimens such as use the nonsteroidal anti-inflammatory drug aspirin may have severe side effects, namely gastrointestinal ulceration and bleeding. Therefore, there is an urgent need of developing alternative strategies. Recently, increasing evidence suggests that several dietary cancer chemopreventive phytochemicals possess anti-inflammation and antioxidative stress activities, and may prevent cancers including CRC. Curcumin (CUR) is the yellow pigment that is found in the rhizomes of turmeric (Curcuma longa). Many studies have demonstrated that CUR exhibit strong anticancer, antioxidative stress, and anti-inflammatory activities by regulating signaling pathways, such as nuclear factor erythroid-2-related factor 2, nuclear factor-κB, and epigenetics/epigenomics pathways of histones modifications, and DNA methylation. In this review, we will discuss the latest evidence in epigenetics/epigenomics alterations by CUR in CRC and their potential contribution in the prevention of CRC.