Key residues revealed in a major conformational epitope of the U1-70K protein

Epitopes depending on three-dimensional folding of proteins have during recent years been acknowledged to be main targets for many autoantibodies. However, a detailed resolution of conformation-dependent epitopes has to date not been achieved in spite of its importance for understanding the complex interaction between an autoantigen and the immune system. In analysis of immunodominant epitopes of the U1-70K protein, the major autoantigen recognized by human ribonucleoprotein (RNP)-positive sera, we have used diversely mutated recombinant Drosophila melanogaster 70K proteins as antigens in assays for human anti-RNP antibodies. Thus, the contribution of individual amino acids to antigenicity could be assayed with the overall structure of the major antigenic domain preserved, and analysis of how antigenicity can be reconstituted rather than obliterated was enabled. Our results reveal that amino acid residue 125 is situated at a crucial position for recognition by human anti-RNP autoantibodies and that flanking residues at positions 119-126 also appear to be of utmost importance for recognition. These results are discussed in relation to structural models of RNA-binding domains, and tertiary structure modeling indicates that the residues 119-126 are situated at easily accessible positions in the end of an alpha-helix in the RNA binding region. This study identifies a major conformation-dependent epitope of the U1-70K protein and demonstrates the significance of individual amino acids in conformational epitopes. Using this model, we believe it will be possible to analyze other immunodominant regions in which protein conformation has a strong impact.

The roles of social class of origin, achieved social class and intergenerational social mobility in explaining social-class inequalities in alcoholism among young men

The aim of this study was to investigate the role of intergenerational health-related mobility in explaining social-class inequalities in alcoholism among young men. Data on social class of origin and on risk factors in childhood and adolescence, e.g. risk use of alcohol, were collected for 49,323 men, born 1949-51, at enlistment for compulsory military training in 1969/70. Information on achieved socioeconomic class was obtained from Sweden's 1975 census. Data on alcoholism diagnoses were collected from the national in-patient care register 1976-83. Risk indicators for alcoholism established in adolescence were found to be more common among downwardly mobile individuals, and also among stable manual workers, than among those who ended up as non-manual employees. Downwardly mobile individuals, and also stable manual workers, were also found to have an increased risk of alcoholism diagnosis. The increased relative risk could, to a considerable extent, be attributed to factors from childhood/adolescence. In this longitudinal study, it is shown that intergenerational social mobility associated with health-related factors, albeit not with illness itself, made a major contribution to explaining differences in alcoholism between social classes. Factors established in adolescence were important with regard to differences in alcoholism between social classes among young adults. But such adverse conditions did not seem to be well reflected by social class of origin.

Genetic analysis of the contribution of IL10 to systemic lupus erythematosus

OBJECTIVE

To study the contribution of the IL10 gene to the susceptibility to systemic lupus erythematosus (SLE).

METHODS

Analysis by fluorescent-semiautomated genotyping of a dinucleotide repeat located in the promoter region of the IL10 locus (microsatellite G).

RESULTS

No significant difference was found in the frequencies of the microsatellite alleles of 330 Mexican patients with SLE compared to 368 controls from the same population. Two-point linkage analyses were carried out using 13 Mexican, 13 Swedish, and 8 Icelandic families with 2 or more cases with SLE. No linkage was revealed between IL10 and SLE, using a variety of parameter settings.

CONCLUSION

Our results do not support that the IL10 gene contributes to the susceptibility to SLE in the populations we studied.

Psychosocial characteristics in young men as predictors of early disability pension with a psychiatric diagnosis

BACKGROUND

There is little knowledge about disability pensions (DPs) in psychiatric diagnoses. The aim of this study was to analyse risk factors among men for receiving an early disability pension with a psychiatric diagnosis.

METHODS

The study is based on data from a nationwide survey of 49 285 young Swedish men who were conscripted into military service in 1969/1970. Potential psychosocial and behavioural risk factors were linked to records from the Swedish Social Insurance Board up until 1993.

RESULTS

The majority (63.4%) of the men granted a DP during follow-up had a psychiatric diagnosis as the main and/or secondary diagnosis. Among those conscripts analysed (41 702), 599 had been granted a disability pension with a psychiatric diagnosis. Of these, 35.4% had a diagnosis of psychosis, 23.2% an alcohol- or drug-related diagnosis, and 41.4% 'other' psychiatric diagnosis. Receiving a psychiatric diagnosis at conscription, showing low emotional control, unemployment after graduation, and ranking low on an "IQ" test were strong predictors of all categories of DP with psychiatric diagnoses. In multivariate analysis controlling for the effect of all other risk indicators included in the model, DP with non-alcohol- and non-drug-related psychiatric diagnoses was related to low social support at adolescence but not to signs of extrovert deviant behaviour (risky use of alcohol or contact with police and child authorities). In contrast, DP with an alcohol- or drug-related diagnosis had strong associations with signs of extrovert deviant behaviour. The risk pattern of DP without psychiatric diagnoses was similar to that of DP with a psychosis but also, though to a lesser extent, to that of DP with 'other' psychiatric diagnosis. These similarities could be interpreted as showing that the diagnoses on the records of disability pensions have a low sensitivity and/or specificity or, alternatively, that the risk factors found are risk factors for life careers steering toward a disability pension rather than toward the specific health outcomes per se.

CONCLUSIONS

The results illustrate the importance of psychosocial factors established in late adolescence in the complex pathway of a decision of an early DP.

Organophosphate neuropathy due to methamidophos: biochemical and neurophysiological markers

Neuropathy target esterase (NTE), the putative target enzyme for organophosphate induced delayed polyneuropathy (OPIDP), can be measured in lymphocytes but has rarely been assessed in acute human poisoning. Serum autoantibodies to nervous system proteins develop in hens poisoned with neuropathic insecticides and also have not been studied after human poisoning. Serial lymphocyte NTE (LNTE) was measured in a 16-year-old boy after acute poisoning with methamidophos for evaluation as a predictor of subsequent neuropathy. The profiles of serum autoantibodies to neurofilament triplet proteins, myelin basic protein, and glial fibrillary acidic protein were measured in order to characterize changes occurring as a result of OPIDP. Clinical neuropathy characterized by steppage gate and profound lower extremity weakness, decreased grip and pinch strength, and decreased ulnar and absent tibial compound muscle action potentials developed 2 weeks following poisoning. Sensory examination and nerve conduction studies were normal. On day 3 following poisoning LNTE was depressed (77% compared with subsequent baseline enzyme activity). Marked increases in serum immunoglobulin G (IgG) autoantibodies to glial fibrillary acidic protein and to neurofilament 200 were observed after the development of OPIDP. We conclude that inhibition of lymphocyte NTE is predictive of subsequent OPIDP. Serum autoantibody titers to nervous system proteins may be useful markers of neuropathy.

Exercise and variations in neuropeptide concentrations in rheumatoid arthritis

The aim of the present study was to investigate the influence of an exercise program on neuropeptide concentrations, disease activity, impairments and disabilities in rheumatoid arthritis (RA). Eleven females (median age 60 years, median disease duration 6.5 years, ARA functional classes I or II) exercised 30 min daily for 4 weeks. The urine concentrations of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and neuropeptide Y-like immunoreactivity (NPY-LI) were analyzed 1 week prior to exercise start, at exercise start, after 2 and 4 weeks of exercise, and after a 4-week follow-up period. Measurements of disease activity, aerobic capacity, grip force, limb muscle function, and activities of daily living (ADL) were also undertaken. The results indicate a decrease (md 5.64 pM to md 3.48 pM, P</=0.05) of CGRP-LI concentrations after 4 weeks' exercise. NPY-LI concentrations remained unchanged, as did disease activity and aerobic capacity. Muscle function and ADL capacity improved significantly (P</=0.05) after the exercise period. Only the improved grip force remained after the follow-up period. In conclusion the results indicate that decreased CGRP-LI concentration, probably reflecting a decreased sympathetic tone, follows physical exercise and suggest that regular physical activity might be important among individuals with RA to maintain a decreased sympathetic tone and less symptoms from their disease.

Increased number of interleukin-10-producing cells in systemic lupus erythematosus patients and their first-degree relatives and spouses in Icelandic multicase families

OBJECTIVE

To evaluate the production of interleukin-10 (IL-10) as well as levels of IgG and antinuclear antibodies (ANA) in systemic lupus erythematosus (SLE) patients and their first-degree relatives and spouses in Icelandic SLE multicase families.

METHODS

IL-10 production was studied by enzyme-linked immunospot assay of freshly isolated peripheral blood mononuclear cells. Total IgG and ANA were also investigated. Subjects consisted of 23 SLE patients and 47 of their first-degree relatives in 9 Icelandic multicase families. Subjects were ethnically matched by a group of healthy controls. A separate study investigated 12 SLE patients (also from SLE multicase families) and their spouses and a matched group of healthy controls. A predefined protocol was used to obtain both clinical and laboratory data, including information about SLE and other autoimmune disorders.

RESULTS

The SLE patients had a significantly higher number of IL-10-producing cells compared with both first-degree relatives and healthy controls (P = 0.0005 and P < 0.0001, respectively). First-degree relatives also had a significantly higher number of IL-10-producing cells compared with healthy controls (P = 0.01). This was also true for the spouses of SLE patients, who had a higher number of IL-10-producing cells compared with matched healthy controls (P = 0.02).

CONCLUSION

SLE patients and their first-degree relatives, as well as a limited number of healthy spouses of SLE patients, had increased numbers of spontaneous IL-10-producing cells. These data support the hypothesis that IL-10 production may be genetically determined, and may predispose one toward development of SLE. This has previously been suggested by studies of SLE patients and their relatives in another ethnic population, using another method for measuring IL-10 production. Although these data are based on a small number of observations, they suggest that not only genetic but also environmental factors may be of importance in determining IL-10 production, since the spouses of SLE patients also had an increased number of IL-10-producing cells.

A comparison of genome-scans performed in multicase families with systemic lupus erythematosus from different population groups

Systemic lupus erythematosus is a disease of unknown etiology. Multiple genetic factors are believed to be involved in its pathogenesis. In addition, and due to genetic heterogeneity, these factors and/or their combinations may be different in different ethnic groups, while some might be shared between populations. We have performed genome scans in multicase families from three different population groups, two from Northern Europe, with a high degree of homogeneity, and the third from a recently admixed population of Mexican Mestizos. Although our family material is relatively small, the results presented here show that using family sets from well defined populations are sufficient to detect susceptibility loci for SLE. Our results also reveal the chromosomal regions most likely to contain susceptibility genes for SLE.

Safety of a home exercise programme in patients with polymyositis and dermatomyositis: a pilot study

OBJECTIVES

To investigate whether a home exercise programme could safely be performed by patients with stable, inactive polymyositis (PM) and dermatomyositis (DM), regarding disease activity, muscle function, health status and pain.

METHODS

Ten patients with reduced muscle function completed the study. A home exercise programme including exercises for strength in the upper and lower limbs, neck and trunk, for mobility in the upper limbs and moderate stretching was developed. The patients exercised for 15 min and took a 15 min walk 5 days a week during a 12 week period. Assessments included clinical evaluation of disease activity, serum creatinine phosphokinase (CPK) levels, magnetic resonance imaging (MRI) of the quadriceps, repeated muscle biopsy of the vastus lateralis, a muscle function index (FI), a walking test and a health status instrument (the SF 36) performed at the start of the study and after 12 weeks.

RESULTS

After 12 weeks of exercise, there were no signs of increased disease activity as assessed clinically, by CPK values, MRI or muscle biopsy findings. On an individual basis, all patients improved regarding muscle function according to the FI, in six cases the improvement reached statistical significance (P < 0.05). A significant improvement regarding muscle function in the upper and lower limbs, walking distance and general health status was achieved.

CONCLUSIONS

Our results indicate that this home exercise programme can be safely employed in patients with stable, inactive PM and DM, with beneficial effects on muscle function.

Collaboration between developing and developed countries and between developing countries in occupational health research and surveillance

Collaborative occupational health and safety studies between counterparts in developing and developed countries and between developing countries have demonstrated their potential for improving occupational health and safety. Such collaboration in occupational health and safety is encouraged in the development of infrastructure in research empowerment and capacity building. This action includes the setting of priorities, the identification and documentation of problems, sponsorship, data bases and surveillance systems, technical support, methodology, publishing, research and training programs, controlled intervention, information exchange, and networking. Examples of priorities in occupational health and safety in the developing world include the informal sector (informally hired and independent workers), temporary work, pesticides, accidents, dusts, carcinogens, solvents, ergonomics, women and child labor, human immunodeficiency virus/acquired immunodeficiencey syndrome (HIV/AIDS), and transfer of hazardous materials and technologies. The sustainability of occupational health and safety structures and functions in the developing countries is a primary concern. Socioethical principles emphasize local, national, mutual and global gains. Examples of collaboration are given. Pervasive problems and strategies toward their solution are highlighted.

Antibodies against lysophosphatidylcholine and oxidized LDL in patients with SLE

Lysophosphatidylcholine (LPC) is present in oxidized low density lipoprotein (oxLDL), which is implicated in atherosclerosis. Antibodies to cardiolipin (aCL) and oxLDL (aoxLDL) have been shown to crossreact. LPC is formed by hydrolysis of phosphatidylcholine (PC) in LDL and cell membranes, induced by phospholipase A2 or by oxidation. We here demonstrate the presence of enhanced antibody levels to LPC in 184 patients with SLE as compared to 85 healthy, age-matched controls. The antibody reactivity to LPC was not specifically related to oxidation of the fatty acid moiety in LPC, since LPC containing only the saturated fatty acid palmitic acid showed equivalent antibody levels as LPC containing unsaturated fatty acids. aPC were significantly lower as compared to aLPC, indicating that hydrolysis of PC at the sn-2 position increases the antigenic potential of the molecule. Beta-glycoprotein 1 was a cofactor for aCL, but not for aoxLDL or aLPC, and the antigenicity of these compounds is therefore not directly related to beta2GP1. There was a close correlation between aoxLDL, aCL and aLPC and both LPC and oxLDL competitively inhibited aCL-binding to CL. LPC, oxLDL and CL thus display a common antigenic site, which could be formed by removal of a fatty acid at the sn-2 position, possibly due to the activity to phospholipase A2 and/or oxidation. This study indicates the potential role of LDL-oxidation and phospholipase A2 in SLE.

Antibodies to adult human endothelial cells cross-react with oxidized low-density lipoprotein and beta 2-glycoprotein I (beta 2-GPI) in systemic lupus erythematosus

Cardiovascular manifestations are common in systemic lupus erythematosus (SLE). Oxidized low-density lipoprotein (oxLDL) is implicated in cardiovascular disease, especially atherosclerosis, and cross-reacts with antibodies to cardiolipin (aCL). beta 2-GPI is a plasma protein participating in the coagulating cascade, and is also cofactor for aCL, and some aCL have been shown to be directed against beta 2-GPI and/or complexes between beta 2-GPI and phospholipids. Lysophosphatidylcholine (LPC) is a phospholipid present both in oxLDL and in damaged endothelium, and we recently showed that LPC is involved in the antigenicity of oxLDL. Antibodies to endothelial cells (aEC) correlate with diseases activity in SLE and vasculitis, and we recently showed that aEC are enhanced in cardiovascular disease such as borderline hypertension and early atherosclerosis. aEC were determined using EC from adult V. Saphena Magna. Antibody levels were determined by ELISA. aEC of IgG type were enhanced in 184 patients with SLE compared with 85 healthy controls. There was a close correlation between aoxLDL, aCL, aLPC, a beta 2-GPI and aEC. Binding of sera to EC was competitively inhibited by beta 2-GPI, LPC and oxLDL. Taken together, the data indicate that EC share antigenic epitopes with beta 2-GPI and with oxLDL, especially LPC. Phospholipids in EC membranes may thus be antigenic epitopes. beta 2-GPI may bind to these phospholipids, and become an autoantigen. LPC is formed by oxidation of phospholipids and/or proinflammatory factors leading to activation of phospholipase A2, and the findings indicate the potential role of both lipid oxidation and phospholipase A2 in SLE.

Mortality of short-term workers in two international cohorts

The purpose of this study was to compare the pattern of mortality of blue-collar workers employed less and more than 1 year in the man-made vitreous fiber (MMVF) and the reinforced plastic industries, the latter group being exposed to styrene. We conducted an analysis among 21,784 workers with less than 1 year of employment (short-term workers) and 19,117 workers with 1 or more years of employment (long-term workers) employed in eight European countries. We conducted analyses based on external as well as internal comparisons. In both cohorts, the standardized mortality ratio for all causes among short-term workers was approximately 40% higher, compared with that for longer-term workers. In internal comparisons, the difference was reduced to 9% in the MMVF cohort and 11% in the styrene cohort. Workers with less than 1 month of employment displayed an increased mortality in both cohorts and in most countries. The increased mortality among short-term workers was not concentrated shortly after they quit employment. In both cohorts, short-term workers had a higher mortality from external causes, while little difference was seen in mortality from ischemic heart disease and malignant neoplasms. Although extra-occupational factors may contribute to increase the mortality of short-term workers and, in particular, of those employed for less than 1 month, the difference observed in analyses adjusted for characteristics of employment suggested a relatively small difference in mortality from most causes.

Explanations of social class differences in alcoholism among young men

The aim of this study was to analyse the role of differences in alcohol consumption and other risk factors for alcoholism established in late adolescence, for later differences in the distribution of alcoholism between social classes among young men. Data on risk factors in childhood and adolescence, e.g. risk use of alcohol, was collected among 49,323 men, born 1949-1951, at conscription for compulsory military training 1969/1970. Data on socio-economic group was obtained from the 1975 census and data on alcoholism diagnoses from the national in-patient care register 1976-1983. Several risk factors for alcoholism, such as risk use of alcohol, psychiatric diagnosis at conscription, parental divorce, low emotional control and contact with police and child care authorities, seemed to be more common among those who were recruited to blue-collar occupations compared to those who were recruited to non-manual occupations. In multivariate analyses, taking the background variables into consideration, the increased relative risks among manual workers for alcoholism diagnoses, found in univariate analyses, diminished considerably. Several risk factors had a stronger effect on the outcome among unskilled workers compared with non-manual employees at medium or higher degree. It is concluded that risk factors for poor health established in late adolescence could explain much of the increased relative risk of alcoholism among young unskilled and skilled male workers in this study.

Central nervous system nitric oxide formation in cerebral systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an inflammatory disease in which up to two thirds of the patients present neurological symptoms. The diagnosis of the disease is based on clinical findings and the presence of autoantibodies, and the pathogenesis is unclear. The purpose of this study was to determine if the pathogenesis was partly mediated via nitric oxide (NO) formation. Cerebrospinal fluid (CSF) samples from 15 patients with cerebral SLE were analyzed for the NO metabolites nitrite and nitrate using capillary electrophoresis. The severity of neurological symptoms was scored by dividing the patients into two groups with either mild or moderate/severe CNS involvement. All patients with cerebral SLE showed increased levels of NO metabolites. In CSF, there was a relationship between signs of NO production and clinical results showing that increased levels of nitrite and nitrate were associated with more severe neurological symptoms. These findings may shed new light on the pathogenesis of cerebral SLE, and analysis of nitrate and nitrate may prove to be of value in monitoring the activity of the disease.

Increased serum levels of immunoglobulins, C-reactive protein, type 1 and type 2 cytokines in patients with mixed connective tissue disease

It is controversial whether mixed connective tissue disease (MCTD) should be regarded as a distinct disease entity. In the present study, we investigated immunological parameters in patients with MCTD by studying serum levels of immunoglobulins, C-reactive protein (CRP) and cytokines and compared the results to the corresponding values in systemic lupus erythematosus (SLE), in rheumatoid arthritis (RA) patients and in healthy controls. Using the ELISA technique, serum levels of the cytokines interferon-gamma (IFN-gamma), interleukin-10 (IL-10) and tumour necrosis factor-alpha (TNF-alpha) were investigated. Cytokine levels in SLE and MCTD were correlated to disease activity as assessed by systemic lupus activity measure (SLAM). They were also correlated to serum levels of CRP, IgG, IgA and IgM in the three patient groups. The MCTD patients had the highest levels of immunoglobulins, followed by the SLE patients. In contrast, the highest CRP levels were observed in RA patients, followed by the MCTD patients. The MCTD patients had the highest serum levels of IL-10, but also had elevated IFN-gamma and TNF-alpha levels similar to the RA patients. There was no correlation between the investigated cytokine levels and disease activity, as assessed by SLAM. We conclude that MCTD patients have high immunoglobulin levels as well as high CRP levels and that this situation is compatible with the observed increase in both type 1 and type 2 cytokine levels. The findings imply that MCTD shares some distinct immunological properties with both RA and SLE and that MCTD may also be considered as a separate disease entity according to these properties.

Why is learning to read a hard task for some children?

In this brief review of some of my research on reading disability, I argue that a child's development into literacy has two major ontogenetic roots, one involving early informal literacy socialization and one related to phonological awareness. Although failure in reading acquisition might be a question of cultural deprivation, the dynamic interaction between genetic dispositions and environment must be acknowledged, especially in a society providing rich sources of print exposure. The crucial transition in literacy development involves a step from implicit to explicit control of the phonemic units of language. When the cipher of the alphabetic system is understood the child is equipped with a powerful instrument for self teaching. A primary source of reading disability is then related to problems of segmenting the speech stream into phonemic units. The poor functioning of the phonological module seems to be a circumscribed deficit not related to general cognitive ability. The causal and reciprocal relationship between phonological awareness and learning to read has been demonstrated in my research over 20 years. Some of these studies are briefly reviewed in this article. The preventive and remedial implications of the findings are rather obvious.

Mortality and cancer incidence among Swedish paint industry workers with long-term exposure to organic solvents

OBJECTIVES

The aim of this update on a cohort of male paint industry workers was to determine whether an excess of mortality and incidence of lymphatic and hematopoietic tumors, particularly multiple myeloma, still exists, and, if so, to determine if it is due to exposures occurring before the mid-1950s, when benzene disappeared as a solvent in the Swedish paint industry.

METHODS

The cohort of 411 men who had worked in the Swedish paint industry and had been exposed to organic solvents for at least 5 years during 1955-1975 was followed from 1961 to 1994 for causes of death in the mortality register and from 1961 to 1992 for cases of cancer in the Swedish cancer register.

RESULTS

The number of paint industry workers who had died, plus the number of deaths in the major disease groups and the number of cancers reported to the cancer registry, was close to the expected. The incidence of prostatic cancer increased somewhat [standardized incidence ratio (SIR) 1.5, 95% confidence interval (95% CI) 1.0-2.2]. Among the workers first employed in 1956 or earlier, there was an increase in both the incidence and mortality from all lymphatic and hematopoietic tumors [SIR 2.3, 95% CI 1.0-2.2; standardized mortality ratio (SMR) 2.0, 95% CI 0.7-4.4]. The excess was particularly marked for multiple myeloma (SIR 3.8, 95% CI 0.8-11; SMR 4.4, 95% CI 0.9-13).

CONCLUSIONS

Employment in the Swedish paint industry before 1957 may have entailed some excess risk of lymphatic and hematopoietic tumors, particularly multiple myeloma. A significant excess of prostatic cancer was not linked to any particular employment period and deserves further investigation.

Work control, work demands, and work social support in relation to alcoholism among young men

OBJECTIVES

The aim of the study was to estimate the impact of psychosocial work-environment factors, such as low work control, on alcoholism among young men.

METHODS

Data on circumstances during childhood and adolescence, such as on risk use of alcohol, were collected for 49,323 young men, born 1949 to 1951 at time of enlistment for compulsory military training in 1969/1970. On the basis of census data on occupation in 1975, all individuals were classified into groups with regard to psychosocial work-environment factors in accordance with a job-exposure matrix. Follow-up for alcoholism diagnoses from inpatient care registers (1976 to 1983) was undertaken for each of the groups. A number of potential confounding factors were taken into account

RESULTS

Low work control and also low job demands and low workplace social support were found to be related to later alcoholism. On separate analysis, the pattern among blue-collar workers was found to be similar to that of the entire population. When the analyses were extended to include indicators of risk use of alcohol and other relevant background factors, the relative risks decreased, but were still significantly high in the cases of low work control and low work social support. A combination of low demands and low control, what might be called a "passive" work environment, was related to an increased relative risk of psychiatric alcoholism diagnosis after controlling for relevant background factors.

CONCLUSIONS

Low work control, in particular in combination with low work demands, and low work social support are related to later alcoholism even after controlling for previously known risk factors (including risk use of alcohol). The results suggest that young men may respond to an undemanding occupational environment by increasing their alcohol consumption.

Ro/SS-A and La/SS-B antibody level variation in patients with Sjögren's syndrome and systemic lupus erythematosus

To examine both possible correlations between anti-Ro/SS-A and anti-La/SS-B levels and their correlation with clinical disease activity in patients with Sjögren's syndrome (SS) or systemic lupus erythematosus (SLE), an ELISA was developed using purified recombinant Ro 60 kDa, Ro 52 kDa and La antigens. The ELISA was used for testing sequential serum samples from 16 patients with either SS or SLE. The patients were followed for periods between 15 and 128 months, and 3-15 serum samples per patient were analysed and compared with clinically apparent disease activity at the time of sampling in 14 patients. A temporal correlation of antibody levels to Ro and La antigens was found, and antibodies to different epitopes of the Ro 60 kDa protein showed parallel variation in seven of eight patients tested. Co-variation of autoantibody levels and disease activity was found in 11 of 14 patients. In seven of these 11 patients the anti-Ro and anti-La levels were stable and changes in disease activity were minimal during the observation period. In the other four of these 11, changes in disease activity were noted, with an associated change in autoantibody levels. The results suggest that the serological response to Ro and La antigens, as well as to different epitopes of the Ro 60 kDa protein, is antigen driven and regulated by common mechanisms, and indicate a correlation of Ro and La antibodies with pathogenic events.

Occurrence of anti-C1q antibodies in IgA nephropathy

BACKGROUND

The pathogenic mechanisms and the antigens involved in the establishment and progress of IgA nephropathy are unknown. As antibodies against C1q have been reported to correlate with SLE nephritis, we analysed the occurrence of these antibodies in IgA nephropathy in order to investigate the possibility of pathogenetic similarities in these renal disorders.

METHODS

The occurrence of IgA- and IgG anti-C1q antibodies (anti-C1q) were determined by ELISA in patients with IgA nephropathy (n = 36) and SLE nephritis (n = 37), diseases both known to be associated with circulating immune complexes. Levels of these antibodies were also determined in two other glomerular diseases, i.e. idiopathic membranous glomerulonephritis (n = 7) and minimal change disease (n = 2), in which circulating immune complexes are usually not present, and in 40 healthy controls.

RESULTS

IgA anti-C1q was observed in increased titres in 11/36 of the patients with IgA nephropathy, in 2/37 of the patients with SLE nephritis (both with proliferative disease) and in 1/9 of the patients with membranous and minimal change disease (P < 0.001). Increased titres of IgG anti-C1q were observed in 1/36 of the patients with IgA nephropathy, in 17/37 of the patients with SLE nephritis and in 0/9 of the patients with membranous and minimal change disease (P < 0.001). There were no correlations between the levels of anti-C1q antibodies and clinical parameters such as degree of proteinuria, haematuria, or renal function. Nor was there any correlation to the concentration of C3a and the terminal complement complex (TCC) in patients with IgA nephropathy.

CONCLUSIONS

The occurrence of anti-C1q antibodies in both IgA nephropathy and SLE nephritis, albeit of different predominating isotypes, indicates the possibility of a similar pathogenic mechanism involved in these renal disorders. The occurrence of IgA anti-C1q antibodies in patients with IgA nephropathy has to our knowledge not previously been reported.

Predisposing factors in sulphasalazine-induced systemic lupus erythematosus

The aim of this study was to define predisposing factors in patients with sulphasalazine-induced systemic lupus erythematosus (SLE). Eleven patients with onset of SLE or SLE-like syndromes during sulphasalazine treatment are reported. Before the onset of SLE, five of the patients suffered from rheumatoid arthritis (RA), one from psoriatic arthropathy (PsoA), two from juvenile chronic arthritis (JCA) and three from ulcerative colitis (UC). At the time of diagnosis of drug-induced SLE, analysis of antinuclear antibodies (ANA), anti-double-stranded DNA antibodies (anti-dsDNA), anti-histone antibodies (anti-histones), acetylator status of the enzyme N-acetyltransferase 2 (NAT2) and HLA classification were performed. All patients were anti-DNA positive at disease onset and were determined to be slow acetylators. HLA A1 occurred in 4/10 patients, B8 in 5/10. HLA DR 3 was represented in one patient and DR 3(17) in five patients. The DQA1* 0501 allele was observed in 7/10 patients and DQB1 0201* in 6/10. Persistent SLE and development of nephritis were noted in patients with long duration of treatment and high cumulative dose of sulphasalazine (> 1000 g). In sulphasalazine-induced SLE, slow acetylator genotype and HLA haplotypes associated with idiopathic SLE seem to predict disease induction. Further, as the risk of developing persistent SLE and nephritis increases with long-standing sulphasalazine medication, it is of importance to monitor the patients with regard to signs of SLE during the entire treatment period.

Alcoholism in social classes and occupations in Sweden

BACKGROUND

A number of studies have shown variations in the occurrence of alcoholism between different socioeconomic groups and occupations, but it has not been clear to what extent this is related to the average alcohol consumption in the same socioeconomic groups or occupations.

METHODS

The relationship between socioeconomic group and occupation and hospital discharge 1981-1983 due to 'diagnoses related to alcoholism' (AD) (alcohol psychosis, alcoholism, and alcohol intoxication) and liver cirrhosis was studied in a cohort of 375,035 men and 140,139 women in 13 counties in Sweden who had reported the same occupation in the censuses of 1960 and 1970. Data on alcohol consumption in different socioeconomic groups and occupations were collected from a conscription investigation and from the Swedish twin registry with data from 1969/70 and 1973 respectively.

RESULTS

Intermediate or higher non-manual employees had lower risk of AD as well as of liver cirrhosis compared to manual workers for both sexes. Among males several, mostly blue-collar, occupations had increased relative risks of AD. A high level of association was found between the relative risks of AD and liver cirrhosis in socioeconomic groups, and the relative risk of AD in occupations, and the average alcohol consumption in the same socioeconomic groups/occupations among males. Such an association was not evident among women.

CONCLUSION

The study shows, contrary to previous Swedish evidence, that there is a strong relationship between the incidence of alcoholism in socioeconomic groups and occupations and the average alcohol consumption in these groups among men.

Evaluation of the Q16 questionnaire on neurotoxic symptoms and a review of its use

OBJECTIVES

The questionnaire 16 (Q16) is commonly used to study prevalences of neurotoxic symptoms among workers exposed to organic solvents. It has also been recommended that exposed workers reporting more than six symptoms should be referred for further examination of possible chronic toxic encephalopathy. It would be useful to know whether symptoms reported in the questionnaire also reflect impairment of similar functions measured with objective or semiobjective methods in a formerly highly exposed group.

METHODS

135 painters and 71 carpenters answered the Q16, were interviewed about symptoms compatible with an organic brain damage, and took a battery of psychometric tests. A subsample of 52 painters and 45 carpenters were interviewed for psychiatric diagnosis according to Diagnostic and Statistical Manual for Mental Disorders, 3rd version (DSM III) and their vibration thresholds in hands and feet were measured. The entire group was followed up in the register of diagnoses at early retirement 1971-93. The lifetime exposure to organic solvents was assessed. Current exposure to organic solvents was found to be low or none.

RESULTS

The prevalence of people with more than six symptoms in the Q16 rose with increasing cumulative exposure to solvents. The sensitivity of the questionnaire (more than six symptoms) to detect people who were assessed to exhibit symptoms compatible with an organic brain damage was only 38%. One of seven people who had retired early with a diagnosis compatible with a chronic toxic encephalopathy, and two of five people with a psychiatric diagnosis compatible with this condition, had more than six symptoms in the Q16. The agreement between Q16 replies and psychometric test results, as well as other examinations, was low.

CONCLUSIONS

The notable exposure-response relation indicates that the questionnaire is useful for comparison of groups with different exposures to organic solvents. There was low agreement between the number of symptoms on the questionnaire and the assessment of symptoms compatible with organic brain damage, as well as psychiatric, or early retirement diagnoses compatible with chronic toxic encephalopathy. The questionnaire does not seem useful for screening of patients with chronic toxic encephalopathy in groups without ongoing exposure to organic solvents.

Cytokine production in muscle tissue of patients with idiopathic inflammatory myopathies

OBJECTIVE

To study cytokine expression in muscle tissues of patients with inflammatory myopathies and to compare the profiles of patients with polymyositis (PM), inclusion body myositis (IBM), and dermatomyositis (DM).

METHODS

We performed indirect immunohistochemistry studies of muscle tissue sections with a panel of 16 different cytokine-specific monoclonal antibodies, directed against interleukin-1alpha, (IL-1alpha), IL-1beta, IL-1 receptor antagonist (IL-1Ra), IL-2, IL-3, IL-4, IL-6, IL-8, IL-10, IL-13, interferon-gamma (IFN gamma), tumor necrosis factor alpha (TNF alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), transforming growth factor beta1 (TGF beta1), TGF beta2, and TGF beta3 in 5 untreated patients each with PM, DM, and IBM and in 4 normal controls. Fresh frozen muscle tissue sections were fixed in formaldehyde before the procedure. The use of saponin as a detergent to permeabilize the cell membranes enabled identification of intracellular cytokine production.

RESULTS

The most prominent finding was the expression of IL-1alpha observed in all patients but in none of the normal controls. In all patients with PM, DM, and IBM, IL-1alpha was expressed in endothelial cells of capillaries, arterioles, and venules in areas surrounded by inflammatory cells, and also in areas with no or scarce inflammatory cells in both endomysium and perimysium. Furthermore, IL-1alpha was also expressed in mononuclear inflammatory cells in all 15 cases. IL-1beta was observed in inflammatory cells in 10 of the 15 patients but, in contrast to IL-1alpha, it was not expressed in blood vessel walls. TGF beta1, TGF beta2, and TGF beta3 were strongly positive in all 15 patients, but only scattered cells were positive in the normal controls. The remaining cytokines were observed only in relatively few cells and only in occasional patients (although the patients were selected for the presence of large infiltrates), and in none of the controls. The patterns were similar in PM, DM, and IBM.

CONCLUSION

Cytokine expression in muscle tissue of patients with inflammatory myopathy is dominated by IL-1alpha, IL-1beta, and TGF beta1-3. The predominant IL-1alpha expression in the blood vessels indicates an importance of the endothelial cells in the inflammatory process in PM, IBM, and DM. A sustained, local release of T cell-derived cytokines may not be a requirement for tissue injury in the inflammatory myopathies. There does not appear to be a qualitative difference in cytokine expression patterns in PM, IBM, and DM.

Health-related selection to seafaring occupations and its effects on morbidity and mortality

This study investigates the relative extents to which health-related selection and the occupation itself might explain increased mortality and morbidity among seafarers. The study group comprised a cohort of young men conscripted for compulsory military training in Sweden during 1969-1970. At conscription, information on ill health and also a number of health-related factors, such as alcohol consumption, was collected. Information on occupation over the period 1970-1990 was extracted from census data. Subjects were 206 men who had been seamen in either 1970 or 1975, or both. These men were compared with 16,292 other men who were unskilled workers during these years. Information on mortality, psychiatric diagnoses and early retirement was collected from relevant registers. Health-related selection was found among persons entering the occupation of seaman. Seamen were also found to have increased relative risks of mortality, early retirement, and psychiatric diagnosis (both related to and not related to alcohol or drug abuse), even after taking into account several background variables concerned with circumstances during childhood and adolescence. Health-related selection was only partly able to explain the increased relative risks faced by seamen found in this study. The occupation itself remains a strong risk indicator, even after controlling for a large number of selection factors.

European Union System for the Evaluation of Substances (EUSES). Principles and structure

In the European Union, Directive 92/32/EC and EC Council Regulation (EC) 793/93 require the risk assessment of new and existing substances, respectively. Principles for this risk assessment have been laid down, supported by a detailed package of Technical Guidance Documents. Against this background the European Union System for the Evaluation of Substances (EUSES) has been developed. This software can be used to carry out tiered risk assessments of increasing complexity on the basis of increasing data requirements. The exposure assessment, effects assessment and risk characterisation are carried out for environmental populations as well as for human beings, including workers, consumers and man exposed through the environment. EUSES is the result of a co-ordinated effort of EU Member States, the European Commission and the European Chemical Industry.

Dual-route and connectionist models: a step towards a combined model

Current models of word recognition are mainly constructed within the frameworks of either dual-route or connectionist theories. The most important test of a word recognition model is how it succeeds in accounting for various reading behaviors. In the present paper dual-route and connectionist word recognition models are briefly described and evaluated. As a further development of these models, a combined framework is proposed. An amalgamation of the two main types of models might give a more satisfactory account of various phenomena within word recognition.

Risk of cancer and exposure to gasoline vapors

Until the introduction of self-service around 1970, service station workers in the Nordic countries were exposed to gasoline vapors. Based on measurements reported in the literature, the 8-hour time-weighted average benzene exposure was estimated to be in the range of 0.5-1 mg/m3. We studied the cancer incidence in a cohort of 19,000 service station workers from Denmark, Norway, Sweden, and Finland. They were identified from the 1970 censuses and followed through 20 years, where 1,300 incident cancers were observed. National incidence rates were used for comparison. The incidence was not increased for leukemia (observed = 28, standardized incidence ratio (SIR) = 0.9, 95% confidence interval (CI) 0.6-1.3) not for acute myeloid leukemia (observed = 13, SIR = 1.3, 95% CI 0.7-2.1). The incidence was slightly elevated for kidney cancer observed = 57, SIR = 1.3, 95% CI 1.0-1.7) and for pharyngeal, laryngeal, and lung cancer. A 3.5-fold risk of nasal cancer was found (observed = 12, SIR = 3.5, 95% CI 1.8-6.1). This cohort exposed to gasoline vapors with benzene levels estimated to be 0.5-1 mg/m3 showed no excess risk of leukemia or acute myeloid leukemia, a 30% elevated risk of kidney cancer, and a previously unnoticed risk of nasal cancer.

Increased risk of lung cancer among male professional drivers in urban but not rural areas of Sweden

OBJECTIVES

To study the risk of lung cancer in different subgroups of professional drivers in urban and rural areas of Sweden.

METHODS

Information on occupation and geographical region was obtained from the Swedish census of 1970 and data on the incidence of lung cancer between 1971 and 1984 from the National Swedish Cancer Registry. Professional drivers were separated into bus, taxi, and long and short distance lorry drivers. Comparisons of cumulative incidence of lung cancer were made between each particular group of drivers and gainfully employed men in the same region.

RESULTS

Taxi drivers, and long and short distance lorry drivers in Stockholm County showed increased relative risks (RRs) of lung cancer with the highest risk among the short distance lorry drivers (RR 2.0, 95% confidence interval (95% CI) 1.5 to 2.6). These categories of drivers also showed increased risks in the other two large conurbations in Sweden. In the rest of the country (mainly rural areas) there were no increased RRs for any category of driver. The RR for bus drivers was not increased in any region. After adjustment for assumed differences in smoking habits the RRs remained significantly increased for lorry drivers in Stockholm but not for other groups of drivers in other areas. However, the RRs remained numerically higher in large conurbations than in rural regions for all groups of drivers.

CONCLUSIONS

These findings suggest that some factors present in the urban environment play a substantial part in the excess of lung cancer among short distance lorry drivers in urban areas of Sweden. Exposure to motor exhaust fumes may have contributed to this excess.

Association between ongoing anti-C1q antibody production in peripheral blood and proliferative nephritis in patients with active systemic lupus erythematosus

The aim of this study was to compare ongoing production of anti-C1q antibodies (anti-C1q) in peripheral blood with serum anti-C1q levels in patients with systemic lupus erythematosus (SLE), especially in patients with nephritis. Using the ELISPOT technique for the detection of IgG and IgA anti-C1q production, 21 patients with active SLE were investigated. ELISAs for IgG and IgA anti-C1q were compared with the ELISPOT results. Six of the patients were found to have proliferative nephritis (WHO grade III/IV) confirmed by renal biopsy. High numbers of IgG anti-C1q spot-forming cells (SFC), defined as > 20/10(5) plated peripheral blood mononuclear cells (PBMC), were exclusively observed in patients with proliferative nephritis (P < 0.0001). Serum levels of IgG anti-C1q were significantly increased in patients with proliferative nephritis (P = 0.039). High ongoing IgG anti-C1q production was observed in all patients with proliferative nephritis, which may be a contributory factor in the pathogenesis of this disorder. The detection of IgG anti-C1q production may be valuable in the clinical investigation of patients with suspected SLE nephritis.

Exposure to styrene and mortality from nervous system diseases and mental disorders

Chronic low-dose exposure to solvents has been associated in epidemiologic studies with chronic neurotoxicity, but the evidence is not consistent. Styrene causes acute disturbances in the central and peripheral nervous systems. To determine if exposure to styrene may contribute to chronic diseases of the central nervous system, the authors examined mortality from nervous system diseases, mental disorders, and suicide in relation to styrene exposure in an international historical cohort study. The cohort involved 35,443 workers employed during 1945-1991 in the reinforced plastics industry, where high exposures to styrene occur. Indicators of exposure were reconstructed through job histories and environmental and biologic monitoring data. Poisson regression was used for internal comparisons. Mortality from diseases of the central nervous system (27 deaths) increased with time since first exposure, duration of exposure, average level of exposure, and cumulative exposure to styrene. A quadratic model described best the dose-response shape for cumulative exposure and duration of exposure with the highest risks at around 300 ppm-years and 5 years, respectively, and a subsequent decrease in risk in the highest exposure categories. Mortality from epilepsy increased monotonically with all styrene exposure indicators, while associations for degenerative diseases of the central nervous system were generally weaker. Mortality from mental disorders and suicide decreased with increasing duration of exposure and cumulative exposure, while there was no trend with time since first exposure and average exposure to styrene. These findings suggest that, in addition to the known acute effects, exposure to styrene may contribute to chronic diseases of the central nervous system.

Neuropsychological verbal tests may lack "hold" properties in occupational studies of neurotoxic effects

OBJECTIVES

In epidemiological studies of neurotoxic effects neuropsychological tests are often applied to assess possible functional changes. In these studies tests presumed to be resistant to neurotoxic effects, "hold tests", are often used to adjust performance in tests presumed to be sensitive to neurotoxic effects, "nonhold tests", in assessment of pre-exposure ability. This conception is based on experience from the examination of patients with organic brain disorders. For this adjustment to be valid hold tests should change comparatively little over time and should not change differently in groups of people with different exposures to neurotoxic agents.

METHODS

These assumptions were examined in 71 carpenters and 135 painters divided in three subgroups according to level of cumulative exposure to organic solvents. The results were noted from two verbal tests (test A, which involved following verbal instructions and test C, word comprehension), which were performed at conscription (age 18-20). The tests resemble hold tests used in occupational studies. The same tests were performed again at the age of 45-60 together with a conventional synonym test (SRB 1), often used in occupational studies.

RESULTS

In the three tests given at the time of the investigation some differences were found between the carpenters and the subgroups of painters. The painters with low exposure tended to perform better than the carpenters in all three tests and the heavily exposed painters tended to perform less well in the tests. These differences were not present at the age of 18-20. In one of the conscription tests painters with different cumulative exposure to organic solvents developed differently over time. There was little improvement among painters with heavy and intermediate exposure and obvious improvement among painters with low exposure. The results in the other conscription test showed similar tendencies.

CONCLUSIONS

The results indicate that the hold tests examined do not meet basic criteria for hold tests used in occupational studies. Thus adjustments for conventional verbal tests seem inappropriate in such studies. It is possible that other presumed hold tests may meet the criteria but our results suggest that such tests also should be evaluated before being used as hold tests in working populations.

Exposure to styrene and mortality from nonmalignant respiratory diseases

A cohort of 34,560 men and 6128 women employed in 660 European factories manufacturing reinforced plastic products, followed up originally to assess the risk of cancer, was used to assess the risk of non-malignant respiratory diseases associated with exposure to styrene. Mortality from pneumonia was associated with intensity of exposure to styrene, but this may have been due to chance. Mortality from bronchitis, emphysema, and asthma was not associated with styrene exposure.

Exposure to styrene and mortality from nonmalignant diseases of the genitourinary system

OBJECTIVES

A historical cohort study was carried out to investigate mortality from nonmalignant diseases of the genitourinary system among workers in the reinforced plastics industry, where high workroom concentrations of styrene are encountered.

METHODS

The external comparisons in this report were based on an average of 12.6 years of retrospective follow-up of 35 443 workers who were first employed in the reinforced plastics industry during 1945-1991 and were known to have been exposed to styrene in their work. For the internal comparisons, 2641 subjects with incomplete occupational histories were excluded, leaving 32 802 subjects. Previous individual exposure histories to styrene were reconstructed through job histories and environmental and biological monitoring data.

RESULTS

Mortality from nonmalignant diseases of the genitourinary system (N = 20) was associated with average exposure to styrene (P for trend 0.05). Weaker increasing trends in risk were seen for time since first exposure and cumulative exposure, while no increase was identified for duration of exposure. There was a significant increasing trend in mortality from nephritis and nephrosis (N = 5), associated with an increasing average level of exposure to styrene (P for trend 0.03). No clear trend was observed for time since first exposure, duration of exposure, or cumulative exposure.

CONCLUSIONS

In this large cohort study of workers exposed to styrene, mortality from nonmalignant diseases of the genitourinary system increased as the average intensity of exposure increased. This finding indicates that other data should be scrutinized.

Analysis of cytokine expression in muscle in inflammatory myopathies, Duchenne dystrophy, and non-weak controls

We investigated the profiles of cytokine mRNA expression in muscle in 15 cases of inflammatory myopathy (IM) (5 each of polymyositis, inclusion body myositis, and dermatomyositis) and in 10 controls (5 of Duchenne dystrophy and 5 non-weak subjects). Expressions of the predominantly T cell-derived cytokines (interleukin (IL)-2, IL-4, IL-5, and interferon-gamma (IFN-gamma), of the predominantly macrophage-derived cytokines (IL-1, IL-6, and tumor necrosis factor-alpha (TNF-alpha)), as well as cytokines that can be of either T cell or macrophage origin (granulocyte-macrophage colony stimulating factor (GM-CSF) and transforming growth factor beta 1 (TGF-beta 1) and TGF-beta 2), were monitored by the reverse transcriptase-PCR method. The expression of T cell cytokine mRNAs for IL-2, IL-5, and IFN-gamma was generally weak or inconsistent. IL-4 mRNA expression was consistently moderate to strong in polymyositis but generally weak or absent in the other IMs. The expression of macrophage cytokine mRNAs for IL-1 alpha and IL-1 beta was weak or absent in all cases. Variable TNF-alpha mRNA expression was observed in 12 of 15 IM cases and faint or weak expression in 5 of 10 controls. Very strong GM-CSF expression was detected, but only on boosted PCR, in 12 of 15 cases of IM but in none of the controls. IL-6 was expressed only weakly or inconsistently. In contrast to the variable expression of several of the above mentioned cytokine mRNAs, all IM specimens strongly expressed TGF-beta 1 mRNA and 12 of 15 strongly expressed TGF-beta 2 mRNA. Thus, with the exception of IL-4 expression in polymyositis, a similar pattern of cytokine mRNA expression exists in the different types of IMs. Moreover, this pattern resembles that detected in non-weak and DD controls, although expression is generally weaker in the non-weak controls. The findings suggest that in IM muscle a sustained secretion of cytokines by T cells or of IL-1 by macrophages is not a prerequisite for operation of the immune effector response and that muscle may not be the site of ongoing sensitization.

Development of a questionnaire in Spanish on neurotoxic symptoms

A questionnaire in Spanish (with yes/no answers) was developed in order to study effects of neurotoxic agents in groups of workers in Nicaragua. Since many workers in Latin America are illiterate, the questions were read to the subjects. The questionnaire initially contained 34 questions, which were reduced to 16 after studying whether the questions were interpreted in the intended way by the subjects, whether the answers were reasonably reproducible over a 3-week period, and whether the questions discriminated between groups exposed to different neurotoxic agents (mercury, lead, organic solvents, and organophosphate insecticides) and nonexposed groups. In total, 851 male workers in Nicaragua and Venezuela participated in the evaluation. The questionnaire is submitted for use in the monitoring of groups exposed to neurotoxic agents, particularly in Latin America. The authors welcome further evaluation.

Cancer incidence and mortality of patients with suspected solvent-related disorders

OBJECTIVE

The aim of this study was to study the incidence of cancer and deaths from cancer and other diseases among patients referred to the 11 clinics of occupational medicine in Sweden between 1967 and 1987 for examination because of exposure to organic solvents.

METHODS

The cohort comprised 5791 persons, 5283 men and 508 women. Information about cancer incidence and causes of death was collected from the Cancer Register of the National Board of Health and Welfare and the National Death Register of Statistics Sweden, respectively. The expected values were calculated from the national death rates and incidence rates of cancer.

RESULTS

The overall mortality rate was close to expected, but the mortality rate was decreased for diseases of the circulatory system [standardized mortality ratio (SMR) 0.7, 95% confidence limit (95% CI) 0.5-0.9] and increased for suicide (SMR 2.0, 95% CI 1.2-3.2). The total cancer incidence was slightly elevated [standardized incidence ratio (SIR) 1.2, 95% CI 0.99-1.4], and some specific cancer sites showed an increased incidence, although the lower confidence limits surpassed one. Malignancies of the lymphohematopoietic system and cancer of the uterine cervix had an increased risk (SIR 1.9, 95% CI 1.2-3.2, and SIR 3.7, 95% CI 2.2-6.2, respectively). Patients with presumerably high solvent exposure had an SIR of 1.4 for all malignancies (95% CI 0.9-2.1) and those with presumerably low exposure had an SIR of 1.1 (95% CI 0.9-1.4).

CONCLUSIONS

The study showed an increased risk for malignancies of the hematopoietic system and the uterine cervix among patients originally examined with regard to solvent-induced disorders. There was also an increased risk of suicide and a decreased risk of death from diseases of the circulatory system. There was no increased risk for deaths from mental or neurological disorders.

Cancer mortality in a historical cohort study of workers exposed to styrene

OBJECTIVES

The goal of this study was to determine whether exposure to styrene is associated with an increased risk for neoplasms of the lymphatic and hematopoietic tissues.

METHODS

A historical cohort study was conducted in Denmark, Finland, Italy, Norway, Sweden, and the United Kingdom. It involved 40,688 workers ever employed in the reinforced plastics industry, where high exposure to styrene occurs. Exposure to styrene was reconstructed through job histories and environmental and biological monitoring data. Cause-specific national death rates were used as the reference. Poisson regression was applied for internal comparisons.

RESULTS

Among the exposed workers, no excess was observed for mortality from all neoplasms. Mortality from neoplasms of the lymphatic and hematopoietic tissues increased with time since first exposure and average level of exposure to styrene, but was not consistently associated with duration of exposure or with cumulative exposure.

CONCLUSIONS

These findings leave open the possibility of an excess risk of neoplasms of the lymphatic and hematopoietic tissues among workers exposed to styrene.

Liver function tests and urinary albumin in house painters with previous heavy exposure to organic solvents

The serum activities or concentrations of aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), alkaline phosphatase (ALP), albumin, gamma-glutamyl transpeptidase (GGT), bilirubin (BIL), cholic acid (CHOL), chenodeoxycholic acid (CHENO), and transferrin with isoelectric point 5.7, and the urinary excretion of albumin were determined among male current or former house painters (n = 135) and house carpenters (n = 71) who had worked in their trades for at least 10 years before 1970. Workers who showed a value above the 90th percentile among the carpenters in at least one of the tests ASAT, ALAT, GGT, BIL, CHOL, or CHENO were regarded as showing "possible signs of liver dysfunction". Each participant's lifetime solvent exposure was evaluated by interview. The painters were divided into categories with low, intermediate, and heavy cumulative exposure during life (LTSE) or during the most exposed year (MEYSE). All participants stated none or slight recent exposure. The prevalence of possible signs of liver dysfunction increased with solvent exposure category according to LTSE as well as MEYSE with a numerically higher risk estimate in the heavy exposure category for MEYSE than for LTSE. ALP activity increased with exposure category according to both exposure estimates. This increase seemed to be due to an interaction between exposure to solvents and current or previous long term intake of medicines potentially toxic to the liver. None of these results was affected by whether or not the subjects had been exposed to solvents during the year before the investigation. The exposure to solvents was not significantly related to any other outcome variable. It is concluded that long term heavy exposure to solvents may elicit changes in conventional liver function tests indicative of a mild chronic effect on the liver. The findings also suggest that heavy solvent exposure during short time periods is a more likely cause of the findings than lifetime cumulative solvent exposure and that an interaction between solvent exposure and medicines potentially harmful to the liver may be important in the causation of the effects.

Occupation, occupational exposure to chemicals and rheumatological disease. A register based cohort study

The cumulative incidence of rheumatoid arthritis (RA) was compared between different occupations, and between different exposure groups based on a job-exposure matrix (JEM). The study population comprised those subjects who in 1980 lived in one of 13 Swedish counties, were born between 1905 and 1945, and who had stated the same occupation in the censuses of 1960 and 1970, a total of 375,035 men and 140,139 women. The study population was followed concerning hospital care for rheumatoid arthritis in 1981-1983 by lineage to the Swedish Hospital Discharge Register. In general there were rather small differences in the relative risk of RA in different exposure groups and different occupations. Most of the occupations associated with an increased risk of RA were occupations in which it was possible to work when the disease was present, i.e. cost accountants, estimating clerks and working proprietors in the retail trade. However, an increased relative risk of RA was also observed in some occupations where selection of RA patients out of heavy work should have biased genuinely increased relative risks towards unity. Such occupations were farmers, upholsterers, lacquerers, concrete workers, and hair-dressers. Substantial handling of organic solvents, according to the JEM, was associated with an increased relative risk.

Acute myeloid leukemia among petrol station attendants

The risk of acute myeloid leukemia (AML) within different occupations was studied, using occupational information obtained from the Swedish 1970 census. Follow-up in the Swedish Cancer Register was carried out from 1971 to 1984. Among male petrol station attendants, 10 cases were observed versus 2.8 expected (observed/expected = 3.6, 95% confidence interval 1.7-6.6). For several decades, Swedish petrol has contained 3-5% of benzene. Thus, a hypothesis was that benzene had contributed to the excess risk. The work histories of the 10 cases were reconstructed through interviews with surviving relatives and were compatible with the hypothesis. However, because the air benzene exposures at petrol stations always have been lower than benzene exposures associated previously with an increased risk of AML, the leukemogenic effect of benzene may have been potentiated by other petrol or vehicle exhaust components.

Dyslexia, left-handedness, and immune disorders

OBJECTIVE

To illuminate a possible three-way association between dyslexia, immune disorders, and left-handedness. Geschwind's, Behan's, and Galaburda's hypotheses have been of special interest in this connection.

DESIGN

Statistical analysis based on general assessment of the prevalence of the three aforementioned conditions.

PARTICIPANTS

There were 734 children included from a total of 1165 in grade 6 (about 12 years of age) in the municipality of Stavanger, Norway.

SETTING

Educational and demographic statistics indicate that the municipality of Stavanger is representative of the national population at large regarding the three conditions examined.

MAIN OUTCOME MEASURES

A screening test with high reliability and validity was used to assess reading ability. It measured word recognition and phonological decoding. The questionnaires that recorded the students' handedness and immune disorders were filled in by the parents. Handedness was assessed by a Norwegian version of the Oldfield Inventory. A questionnaire concerning allergies and asthma was used to assess the prevalence of immune disorders.

RESULTS

The bivariate analyses disclosed a significant association between handedness and dyslexia and a significant but weak association between handedness and immune disorders. No significant association was found between dyslexia and immune disorders. A triadic analysis yielded the following: 66.7% of the left-handed dyslexic children had immune disorders (P > .05); 42.1% of the left-handed children with immune disorders had dyslexia (P < .01); and 32% of the dyslexic children with immune disorders were left-handed (P < .05).

CONCLUSIONS

There seems to be some association between dyslexia, left-handedness, and immune disorders. Of the three factors, handedness seems to be the most important association. The findings lend some support to the one interpretation of the hypotheses of Geschwind, Behan, and Galaburda.

Mortality and cancer incidence among PVC-processing workers in Sweden

The mortality pattern and the cancer incidence were investigated among 717 men who had been employed for at least 3 months during 1964-1974 in three Swedish PVC-processing plants. The mortality was followed 1964-1986 and the cancer incidence 1964-1984. Expected figures were calculated from Swedish national rates. Among Swedish citizens, the observed mortality and cancer incidence was close to the expected in most diagnoses. Among immigrants, mostly from Finland, there was a marked excess of circulatory deaths. This finding was probably due to the higher incidence of coronary mortality in Finland compared to Sweden. In the whole cohort, five cases of malignant melanoma had occurred as compared to 1.5 expected (SMR = 3.4, 95% confidence limit 1.1-7.9). This may be due to chance but merits further investigation since an increased incidence of malignant melanoma has previously been found among Norwegian PVC-manufacturing workers.

IgG and IgM anti-snRNP reactivity in sequentially obtained serum samples from patients with connective tissue diseases

Sequentially obtained serum samples from 30 patients with connective tissue disease positive for antibody to ribonucleoprotein (RNP) were examined to determine the specificities of IgG and IgM antibodies to snRNP during the disease course using immunoblotting of nuclear extracts. The antibody patterns were correlated with disease activity. The patterns of antibody to snRNP of individual patients were mainly stable during the study but changes in levels of antibody to snRNP were seen corresponding to changes in clinical activity. These results indicate that increased reactivity of serum IgM antibodies against the B/B' proteins seems to precede a clinically evident exacerbation of disease whereas IgG antibody reactivity to the 70 K protein peaks at the time of a disease flare.

Clinical manifestations and anti-(U1)snRNP antibodies: a prospective study of 29 anti-RNP antibody positive patients

Twenty-nine anti-RNP positive patients were followed prospectively with a mean observation time of 65 months (29-120 months). The clinical course was correlated to the presence of IgM and IgG anti-(U1)snRNP antibodies as revealed by immunoblotting from sequentially obtained sera. There was a striking dissociation between the fluctuating course, with the appearance of new manifestations followed by remissions, and the stability of the anti-snRNP antibody specificities where an appearance or a disappearance of anti-snRNP specificities was a rare phenomenon. The main epitope recognized by the IgG antibodies was the 70 kDa protein and of the IgM antibodies the B/B' proteins. No shift from the IgM to the IgG isotype was observed. The presence of IgG anti-70 kDa and IgM anti-B/B' antibodies was highly associated with presence of arthralgias, Raynaud's phenomenon and arthritis. Further, an association was noted between the combined presence of IgG anti-70 kDa, anti-A and anti-C antibodies and IgM anti-B/B' and puffy hands, myositis, pulmonary fibrosis and sclerodactyly, i.e. all manifestations of mixed connective tissue disease (MCTD). On the contrary, serositis as often seen in SLE was correlated to the presence of IgG anti-B/B' antibodies. Thus the longitudinal analysis of the correlation between anti-snRNP antibody specificities and clinical manifestations support the concept of MCTD as a distinct entity.

A clinical, serological, and histopathological study of myositis patients with and without anti-RNP antibodies

Twenty-nine patients with myositis, including 10 with polymyositis (PM), 6 with dermatomyositis (DM), and 13 with myositis associated with a connective tissue disease (CTD), were followed up for a mean observation time of 49 months. The 13 patients with CTD-associated myositis were further separated by the presence or absence of anti-RNP antibodies. The functional disability at diagnosis was pronounced without differences between the groups. The patients with anti-RNP antibodies did not differ from the other patients regarding initial muscle weakness, erythrocyte sedimentation rate, or creatinine phosphokinase values, but the histopathological muscle changes were generally milder. Rapid improvement of muscle strength on moderate doses of corticosteroids was seen in most patients. At the end of study, corticosteroid treatment had been withdrawn from 17 patients because of remission, including 6 of the 7 patients with anti-RNP antibodies. The presence of electromyographic changes compatible with myositis, pronounced muscle weakness before treatment, and a low erythrocyte sedimentation rate seemed to indicate a less favorable outcome unrelated to diagnostic subgroupings. However, the combination was rarely found among the anti-RNP-positive patients.