Can sensation of cold hands predict Raynaud's phenomenon or paraesthesia?

Background: Raynaud's phenomenon and neurosensory symptoms are common after hand-arm vibration exposure. Knowledge of early signs of vibration injuries is needed. Aims: To investigate the risk of developing Raynaud's phenomenon and paraesthesia in relation to sensation of cold hands in a cohort of male employees at an engineering plant. Methods: We followed a cohort of male manual and office workers at an engineering plant in Sweden for 21 years. At baseline (1987 and 1992) and each follow-up (1992, 1997, 2002, 2008), we assessed sensation of cold, Raynaud's phenomenon and paraesthesia in the hands using questionnaires and measured vibration exposure. We calculated risk estimates with univariate and multiple logistic regression analyses and adjusted for vibration exposure and tobacco usage. Results: There were 241 study participants. During the study period, 21 individuals developed Raynaud's phenomenon and 43 developed paraesthesia. When adjusting the risk of developing Raynaud's phenomenon for vibration exposure and tobacco use, the odds ratios were between 6.0 and 6.3 (95% CI 2.2-17.0). We observed no increased risk for paraesthesia in relation to a sensation of cold hands. Conclusions: A sensation of cold hands was a risk factor for Raynaud's phenomenon. At the individual level, reporting a sensation of cold hands did not appear to be useful information to predict future development of Raynaud's phenomenon given a weak to moderate predictive value. For paraesthesia, the sensation of cold was not a risk factor and there was no predictive value at the individual level.

The mediating role of recovery opportunities on future sickness absence from a gender- and age-sensitive perspective.

A lack of sufficient recovery during and after work may help to explain impaired health in the long run. We aimed to increase knowledge on the mediating role of recovery opportunities (RO) during and after work on future sickness absence from a gender- and age-sensitive perspective. We used data on RO from a Swedish national survey in 2011 and linked these to sickness absence (>14 days) two years later among the general working population (N = 7,649). Mediation of the relationship between gender and sickness absence by exposure to RO was studied through linear regression. We conducted separate analyses for RO during and after work and for three different age groups (16-29; 30-49; 50-64). The sample consisted of 3,563 men and 4,086 women. Sickness absence was higher among the women than among the men (11 days vs 5 days, p<0.001). Men reported statistically significantly more positive on their RO than women. RO during (ß 0.3-1.8) and after work (ß 0.4-0.6) mediated the relationship between gender and sickness absence. Mediation effects existed across age groups, with the strongest effects of RO during work found among the age group between 50 and 64 years of age (attenuation 36%). Our results indicate that gender inequality is also reflected in worse RO among women. This partially explains the increased risk of future sickness absence, particularly among those above 50 years of age. These findings show that RO during work deserve more attention in working life research.

Relationships between work-related factors and musculoskeletal health with current and future work ability among male workers.

PURPOSE: The purpose was to increase job-specific knowledge about individual and work-related factors and their relationship with current and future work ability (WA). We studied cross-sectional relationships between mental demands, physical exertion during work, grip strength, musculoskeletal pain in the upper extremities and WA and the relationships between these variables and WA 11 years later. METHODS: We used a dataset of a prospective cohort study (1997-2008) among employees of an engineering plant (n = 157). The cohort was surveyed by means of tests and written questions on work demands, musculoskeletal health, WA score (WAS; 0-10), and mental and physical WA. Spearman correlation coefficients and logistic regression analysis were used. RESULTS: Among manual workers, we found weak correlations between grip strength and current and future physical WA. We did not find predictors for future poor WA among the manual workers. Among the office workers, we found that musculoskeletal pain was moderately and negatively related to current WAS and physical WA. More handgrip strength related to better future WAS and physical WA. Musculoskeletal pain (OR 1.67 p < 0.01) and lower handgrip strength (OR 0.91 p < 0.05) predicted future poor WA among office workers. CONCLUSIONS: Our results showed cross-sectional and longitudinal relationships between musculoskeletal health and work ability depending on occupation. However, the present implies that predicting work ability in the far future based on health surveillance data is rather difficult. Testing the musculoskeletal system (grip strength) and asking workers' about their musculoskeletal health seems relevant when monitoring work ability.

Work ability in vibration-exposed workers.

BACKGROUND: Hand-arm vibration exposure may cause hand-arm vibration syndrome (HAVS) including sensorineural disturbances. AIMS: To investigate which factors had the strongest impact on work ability in vibration-exposed workers. METHODS: A cross-sectional study in which vibration-exposed workers referred to a department of occupational and environmental medicine were compared with a randomized sample of unexposed subjects from the general population of the city of Gothenburg. All participants underwent a structured interview, answered several questionnaires and had a physical examination including measurements of hand and finger muscle strength and vibrotactile and thermal perception thresholds. RESULTS: The vibration-exposed group (47 subjects) showed significantly reduced sensitivity to cold and warmth in digit 2 bilaterally (P < 0.01) and in digit 5 in the left hand (P < 0.05) and to warmth in digit 5 in the right hand (P < 0.01), compared with the 18 referents. Similarly, tactilometry showed significantly raised vibration perception thresholds among the workers (P < 0.05). A strong relationship was found for the following multiple regression model: estimated work ability = 11.4 - 0.1 × age - 2.3 × current stress level - 2.5 × current pain in hands/arms (multiple r = 0.68; P < 0.001). CONCLUSIONS: Vibration-exposed workers showed raised vibrotactile and thermal perception thresholds, compared with unexposed referents. Multiple regression analysis indicated that stress disorders and muscle pain in hands/arms must also be considered when evaluating work ability among subjects with HAVS.

Risk factors, incidence and persistence of symptoms from the eyes among professional computer users.

BACKGROUND: Symptoms from the eyes are common among computer users. Knowledge is scarce about these problems, however. OBJECTIVES: The aim was to study risk-factors, incidence and persistence of eye-symptoms among professionally active computer users. METHODS: This was a questionnaire based prospective study where 1283 males and females from different professions and companies answered a baseline questionnaire about individual factors and working conditions, e.g. duration of daily computer work, comfort of screen work, psychosocial factors. Subjects were at baseline and 10 follow-ups asked about the number of days with eye-symptoms during the preceding month. RESULTS: The incidence-rate of symptoms persisting minimum three days was 0.38/person-year. A multivariate Hazard-ratio model showed significant associations with extended continuous computer work, tasks with high demands on eye-hand coordination, low level of control, visual discomfort, female sex and nicotine use. Eye-symptoms at baseline was a strong risk factor for new symptoms. CONCLUSION: The incidence of eye-symptoms among professional computer users is high and related to both individual and work-related factors. The organization of computer work should secure frequent breaks from near-work at the computer screen. The severity of vision-related problems could in field studies be quantified by asking for the persistence of symptoms.

Incidence and risk factors for symptoms from the eyes among professional computer users.

Personal computers are used by a majority of the working population in their professions. Little is known about risk-factors for incident symptoms from the eyes among professional computer users. The aim was to study the incidence and risk-factors for symptoms from the eyes among professional computer users.This study is a part of a comprehensive prospective follow-up study of factors associated with the incidence of symptoms among professional computer users. 1531 computer users of different professions at 46 companies were invited, whereof 1283 answered a baseline questionnaire (498 men; 785 women) and 1246 at least one of 10 monthly follow-up questionnaires. The computer work-station and equipment were generally of a good standard. The majority used CRT displays.During the follow-up period 329 subjects reported eye symptoms. The overall incidence rate in the whole study group was 0.38 per person-year, 0.23 in the subgroup of subjects who were symptom free at baseline and 1.06 among subjects who reported eye symptoms at baseline. In the bivariate analyses significant associations were found with all explanatory variables, except BMI. The reduced multivariate model showed significant associations with extended computer work, visual discomfort (dose-response), eye symptoms at baseline (higher risk), sex (women=higher risk) and nicotine use.The incidence of eye problems among professional computer users is high and related to both individual and work-related factors.

Black silicon with high density and high aspect ratio nanowhiskers.

The physical properties of black silicon (b-Si) formed on Si wafers by reactive ion etching in chlorine plasma are reported in an attempt to clarify the formation mechanism and the origin of the observed optical and electrical phenomena, which are promising for a variety of applications. The b-Si consisting of high density and high aspect ratio sub-micron length whiskers or pillars with tip diameters of well under 3 nm exhibits strong photoluminescence (PL) both in the visible and the infrared, which is interpreted in conjunction with defects, confinement effects and near band-edge emission. Structural analysis indicates that the whiskers are all crystalline and encapsulated by a thin Si oxide layer. The infrared vibrational spectrum of Si-O-Si bondings in terms of transverse-optic (TO) and longitudinal-optic (LO) phonons indicates that disorder induced LO-TO optical mode coupling can be an effective tool in assessing the structural quality of the b-Si. The same phonons are likely coupled to electrons in visible region PL transitions. Field emission properties of these nanoscopic features are demonstrated indicating the influence of the tip shape on the emission. Overall properties are discussed in terms of the surface morphology of the nanowhiskers.

Expression of four canine leukocyte adhesion factors in fresh and stored whole blood samples evaluated using a no-lyse, no-wash method.

Expression of four leukocyte adhesion factors on canine leukocytes was studied by flow cytometry using a no-lyse, no-wash method. The effect of fixation and storage for up to 14 days in 1% paraformaldehyde on labelled samples and within assay variation was evaluated. Monoclonal antibodies directed to monocyte marker CD14, and to adhesion molecules CD11a, CD18, CD32 and CD49d were used. Cell surface marker, cell population, time, and the interactions between time and cell marker significantly affected expression of cell adhesion factors. For CD18, there was a significant difference in mean fluorescence intensity (MFI) between fresh and stored samples (P<0.001), but no significant difference between stored samples. The MFIs of CD11a and CD49d were not significantly affected by fixation and storage. The CVs differed significantly depending on cell marker (P<0.001) and cell population (P=0.005). Fixation and storage did not significantly affect the CV. In conclusion, a no-lyse, no-wash method can be applied to canine leukocytes. The effect of fixation and storage on the resulting MFI differs between monoclonal antibodies, and should be evaluated for each antibody before use. The coefficient of variation was generally acceptable, and high CVs were related to a low MFIs or low numbers of analysed cells.

Controlled thinning and surface smoothening of silicon nanopillars.

A convenient method has been developed to thin electron beam fabricated silicon nanopillars under controlled surface manipulation by transforming the surface of the pillars to an oxide shell layer followed by the growth of sacrificial ammonium silicon fluoride coating. The results show the formation of an oxide shell and a silicon core without significantly changing the original length and shape of the pillars. The oxide shell layer thickness can be controlled from a few nanometers up to a few hundred nanometers. While downsizing in diameter, smooth Si pillar surfaces of less than 10 nm roughness within 2 microm were produced after exposure to vapors of HF and HNO3 mixture as evidenced by transmission electron microscopy (TEM) analysis. The attempt to expose for long durations leads to the growth of a thick oxide whose strain effect on pillars can be assessed by coupled LO-TO vibrational modes of Si-O bonds. Photoluminescence (PL) of the pillar structures which have been downsized exhibits visible and infrared emissions, which are attributable to microscopic pillars and to the confinement of excited carriers in the Si core, respectively. The formation of smooth core-shell structures while reducing the diameter of the Si pillars has a potential in fabricating nanoscale electronic devices and functional components.

Neck pain combined with arm pain among professional drivers of forest machines and the association with whole-body vibration exposure.

The purpose of this study was to investigate the existence of neck pain and arm pain among professional forest machine drivers and to find out if pain were related to their whole-body vibration (WBV) exposure. A self-administered questionnaire was sent to 529 forest machine drivers in northern Sweden and the response was 63%. Two pain groups were formed; 1) neck pain; 2) neck pain combined with arm pain. From WBV exposure data (recent measurements made according to ISO 2631-1, available information from reports) and from the self-administered questionnaire, 14 various WBV exposure/dose measures were calculated for each driver. The prevalence of neck pain reported both for the previous 12 months and for the previous 7 d was 34% and more than half of them reported neck pain combined with pain in one or both arms. Analysis showed no significant association between neck pain and high WBV exposure; however, cases with neck pain more often experienced shocks and jolts in the vehicle as uncomfortable. There was no significant association between the 14 WBV measures and type of neck pain (neck pain vs. neck pain combined with arm pain). It seems as if characteristics of WBV exposure can explain neither existence nor the type of neck pain amongst professional drivers of forest machines. The logging industry is important for several industrialised countries. Drivers of forest machines frequently report neuromusculoskeletal pain from the neck. The type of neck pain is important for the decision of treatment modality and may be associated with exposure characteristics at work.

Characterization of bovine lymphocytes stimulated in vitro by Dictyocaulus viviparus homogenate.

Adult Dictyocaulus viviparus homogenate induced proliferation of lymphocytes from naïve cattle. We characterized the responding cells by carboxyfluorescein diacetate succinimidyl ester (CFSE) loading, for detection of proliferation, and antibody labelling for cell surface molecules. Lymphocytes expressing CD4, CD8 and gamma/delta TCR, rather than Ig expressing cells, proliferated after in vitro stimulation with D. viviparus homogenate. Of gamma/delta TCR expressing cells, both CD8, WC1.1 and WC1.2 co-expressing cells proliferated. Moreover, gamma/delta T cells expressing MHC class II proliferated to a higher extent than those negative for MHC class II. Of CD4 and CD8 expressing lymphocytes, both those co-expressing CD45R and CD45R0 proliferated. Among CD4 expressing lymphocytes, those that were CD45R0 positive had a larger proportion of proliferated cells than did CD45R positive cells. Compared to stimulation with Con A, the proportion of dividing cells after D. viviparus stimulation was smaller although the cells had divided more times. Furthermore, we also compared in vitro responses of peripheral blood mononuclear cells collected before and after two subsequent infections with D. viviparus, but no clear acquired responses could be detected. Overall, this suggests that most T lymphocytes are stimulated by the D. viviparus homogenate rather than any particular lymphocyte subpopulation.

Thermal perception thresholds among young adults exposed to hand-transmitted vibration.

INTRODUCTION: Quantitative sensory testing assesses non-invasively the function of the sensory pathways from receptors to cortex. Studies of workers exposed to vibration support evidence that neuro-sensory hand-arm vibration syndrome also encompasses neuropathy of the small-diameter nerve fibres. OBJECTIVES: To assess the risk of disturbed thermal perception developing among young adults exposed to vibration and hand-intensive manual work. The aim also encompasses the study of alternative covariates in small-diameter nerve fibre neuropathy assessment. METHODS: This cross-sectional multi-centre study comprised 202 males and females from vocational school programs in auto mechanics, construction and catering. The testing included a baseline questionnaire, a clinical examination focusing on upper extremity disorders and quantitative somatosensory testing. Thermal perception thresholds were assessed, on both hands, second and fifth digits, using a modified Marstock method for warmth and cold. RESULTS: Reduced thermal perception sensitivity was found for digit II compared to digit V, for females compared to males, and between the two study centres. Subjects exposed to vibration at work showed reduced sensitivity to temperature compared to non-vibration exposed. In univariate analyses odds ratios of 1.06 (95% CI 1.006-1.118) and 1.02 (95% CI 0.971-1.078) for reduced perception to cold for the right and left hands, respectively, was found for vibration. This association was lost in multivariate analyses. The study centre was the strongest confounding influence. CONCLUSIONS: Sensitivity to temperature appears to be reduced despite the subjects short exposure-time and low exposure to vibration. The effect is small in relation to other confounding factors. A low agreement between the modalities indicates the need for separate tests for cold and warmth. Hand-side, age, stature, and BMI were not important for thermal perception but study centre, gender and choice of digit were. Conventional electro-diagnostic investigations are inadequate for evaluating the status of the small-fibre afferent systems leaving QST of thermal perception as the preferred diagnostic tool.

Incidence of self-reported reduced productivity owing to musculoskeletal symptoms: association with workplace and individual factors among computer users.

UNLABELLED: The aim of the present study was to assess the incidence and identify possible risk factors for self-reported reduced productivity owing to musculoskeletal symptoms among computer users. DESIGN: a cohort study with a baseline questionnaire and monthly follow ups during 10 months. METHODS: the study base consisted of 1,283 computer users, 636 men and 896 women. Ergonomists observed workstation characteristics before entering the cohort. Cases were defined as subjects reporting reduced productivity or reporting being on sick leave owing to musculoskeletal symptoms. RESULTS: women had approximately two times the incidence of self-reported reduced productivity owing to symptoms in the neck, shoulder and in the forearm/hand than men. There was no difference in gender for the incidence of self-reported reduced productivity owing to back symptoms. Working overtime and job demands were risk factors for self-reported reduced productivity owing to neck and back symptoms. Physical exercise fewer than 8 times the last month was a risk factor for self-reported reduced productivity owing to neck, shoulder and forearm/hand symptoms. Computer mouse use for more than 0.5 h/day was a risk factor for self-reported reduced productivity owing to shoulder and forearm/hand symptoms. CONCLUSIONS: risk factors for self-reported reduced productivity owing to musculoskeletal symptoms included life style factors, such as overweight and low physical exercise, occupational factors, such as overtime, job demands and computer mouse operating time.

Current issues in case definitions for common musculoskeletal disorders in workers for clinical practice and research.

BACKGROUND: Several reviews and attempts at meta-analysis have pointed out that comparisons between studies on work-related musculoskeletal disorders are problematic, since different studies use different case definitions. In a clinical setting, the case definition involves a detailed history, a physical examination, and laboratory testing. DISCUSSION AND CONCLUSIONS: When determining which tests should be included in a clinical examination, it is necessary to take into consideration the characteristics of clinical tests in terms of likelihood ratio for confirming and ruling out disease in addition to the pre-test probability of disease. If the different musculoskeletal symptoms and signs do not completely comply with the criteria for a disease, we recommend the choice of an ICD label (International Classification of Diseases - WHO) that focuses on the symptoms rather than the pathology. We suggest that the process for a new feasible case definition system for the neck and upper extremities should start with the creation of a consensus of criteria for diagnosis of common musculoskeletal disorders in primary care, developed by a panel consisting of researchers in the key disciplines. Furthermore, we suggest that in workers whose musculoskeletal function is crucial for employment, use of the International Classification of Function (ICF) may be one way to improve classification of health problems.

Predictors of leaving nursing care: a longitudinal study among Swedish nursing personnel.

OBJECTIVES: Despite extensive research on turnover among nursing personnel very little is known about the impact of physical workload and health on leaving. The aim of this study was to find predictors for leaving nursing care with special reference to physical working conditions and musculoskeletal problems. METHODS: This study is based on longitudinal data from a survey of nursing personnel who were employed at various county hospitals in Sweden from 1992-95. A self administrated follow up questionnaire was used to identify their present position in the labour market. The response rate was 73% (n = 1095). RESULTS: The results showed that nursing personnel reporting musculoskeletal problems of the neck/shoulder or knees and those who had limited use of transfer devices were more likely to leave nursing care. CONCLUSIONS: The study highlights the importance of taking musculoskeletal problems and use of transfer devices into consideration in order to retain nursing personnel.

Mononuclear cell subsets in bronchoalveolar lavage fluid during Dictyocaulus viviparus infection of calves: a potential role for gamma/delta TCR-expressing cells in airway immune responses?

Mononuclear cell populations in the lungs of calves infected with Dictyocaulus viviparus were studied during primary infection and reinfection in order to identify cells involved in development of protective immunity to parasitic bronchitis. Three groups of calves were either inoculated with 500 third-stage larvae at both weeks 0 and 10 (n = 6), inoculated only at week 10 (n = 6), or remained uninfected (n = 3). The animals were monitored weekly by collection of bronchoalveolar lavage fluid (BALF), blood and faeces. Among mononuclear BALF-cell populations, the gamma/delta TCR-expressing cells showed a pronounced transient increase in proportion as well as in relative cell size 2 weeks post primary infection, whereas CD4-, CD8-, Ig- and CD14-expressing cells showed no significant differences related to the infection. The increase in gamma/delta TCR-expressing cells coincided with significantly increased proportions of eosinophils and recovery of adult worms in BALF. After reinfection, gamma/delta TCR-expressing cells increased again, but not until week 3 post inoculation, whereas eosinophils were increased by week 2 and reached higher levels than after primary infection. After reinfection, establishment of D. viviparus was less successful than after primary infection. In conclusion, these results indicate a role for gamma/delta TCR-expressing lymphocytes in the pathogenesis of D. viviparus infection.

Clinical assessment, prognosis and return to work with reference to work related neck and upper limb disorders.

OBJECTIVES: To describe the clinical assessment and management of work related neck and upper limb disorders. METHODS: A total of 65 references in English were found in Pub Med for the years 1980-2002 that dealt with clinical assessment, prognosis and return to work with reference to neck and upper limb original research that dealt with test performance in diagnostic procedures. Few studies were randomised studies of prognosis and return to work with reference to neck and upper limb disorders. RESULTS: The clinical assessment consists of the clinical and exposure history, the evaluation of the physical and laboratory findings. The physical examination should include the following steps: (1) inspection; (2) testing for range of motion (3) testing for muscle contraction pain and muscle strength (4) palpation of muscle tendons and insertions and (5) specific tests. The characteristics of clinical tests in terms of likelihood ratio for confirming and ruling out disease have to be considered for the diagnosis. The use of terms such as RSI (repetitive strain injuries) and CTD (cumulative trauma disorders) should be avoided. If the different musculoskeletal symptoms and signs do not completely comply with criteria for a disease, it is recommended to choose an ICD (International Classification of Disease) label that focuses on the symptoms rather than the pathology. The prognosis for most work related disorders are variable. The general experience is for non-specific neck and upper arm that pain and discomfort may be decreased but not eliminated in the majority of cases. It is important to start rehabilitation early. Long periods of sick leave are generally counterproductive. Disputed workers' compensation claims and an adverse work setting also are likely to impede successful rehabilitation. Since most patients with musculoskeletal disorders are also exposed to ergonomic stressors accommodation of the injured worker has to take the whole work system into account (task, technology, environment and organization). CONCLUSIONS: Despite the large number of patients with neck and upper limb disorders the scientific evidence for clinical assessment, to determine the prognosis and for successful procedures for return to work are few.

Concordance between VDU-users' ratings of comfort and perceived exertion with experts' observations of workplace layout and working postures.

The aim of the present study was to evaluate the concordance (agreement) between VDU-users' ratings of comfort and ergonomists' observations of workplace layout, and the concordance between VDU-users' ratings of perceived exertion and ergonomists' observations of working postures during VDU-work. The study population consisted of 853 symptom free subjects. Data on perceived comfort in different dimensions and data regarding perceived exertion in different body locations were collected by means of a questionnaire. Data concerning workplace layout and working postures were collected with an observation protocol, by an ergonomist. Concordance between ratings of comfort and observations of workplace layout was reasonably good for the chair and the keyboard (0.60, 0.58) and good regarding the screen and the input device (0.72, 0.61). Concordance between ratings of perceived exertion and observations of working postures indicated good agreement (0.63-0.77) for all measured body locations (neck, shoulder, wrist and trunk). In conclusion ratings of comfort and perceived exertion could be used as cost-efficient and user-friendly methods for practitioners to identify high exposure to poor workplace layout and poor working postures.

Perceived muscular tension, job strain, physical exposure, and associations with neck pain among VDU users; a prospective cohort study.

AIMS: To determine whether perceived muscular tension, job strain, or physical exposure are associated with increased risk of developing neck pain among VDU users. METHODS: A baseline questionnaire was answered by 1283 respondents, of whom 671 were free from neck pain at baseline. Perceived muscular tension, job strain, and physical exposure were assessed at baseline. Information about newly developed neck pain was collected in 10 follow up questionnaires and the case definition was the first report of such pain in any of the follow up questionnaires. Median follow up time was 10.9 months. RESULTS: Both men and women who perceived muscular tension at least a few times per week, compared to those who had not perceived muscular tension the preceding month, had an incidence rate ratio (IRR) of 1.9 (95% CI 1.25 to 2.93) for developing neck pain, when stratifying for sex. High perceived muscular tension was associated with an increased risk (IRR 1.6, 95% CI 1.02 to 1.91), even when controlling for job strain, physical exposure, and age in the model stratified by sex. CONCLUSIONS: Perceived muscular tension was associated with an increased risk of developing neck pain among VDU users. The combination of high job strain and high perceived muscular tension was associated with higher risk of developing neck pain than the combination of high physical exposure and high perceived muscular tension. There was an indication of an excess risk due to interaction between high physical exposure and high job strain.