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In skeletal muscle, excitation-contraction (EC) coupling relies on the mechanical coupling between two ion channels: the L-type voltage-gated calcium channel (Ca V 1.1), located in the sarcolemma and functioning as the voltage sensor of EC coupling, and the ryanodine receptor 1 (RyR1), located on the sarcoplasmic reticulum serving as the calcium release channel. To this day, the molecular mechanism by which these two ion channels are linked remains elusive. However, recently, skeletal muscle EC coupling could be reconstituted in heterologous cells, revealing that only four proteins are essential for this process: Ca V 1.1, RyR1, and the cytosolic proteins Ca V β 1a and STAC3. Due to the crucial role of these proteins in skeletal muscle EC coupling, any mutation that affects any one of these proteins can have devastating consequences, resulting in congenital myopathies and other pathologies.Here, we summarize the current knowledge concerning these four essential proteins and discuss the pathophysiology of the Ca V 1.1, RyR1, and STAC3-related skeletal muscle diseases with an emphasis on the molecular mechanisms. Being part of the same signalosome, mutations in different proteins often result in congenital myopathies with similar symptoms or even in the same disease., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Purpose: We investigated the effect of shift work on headache. Furthermore, we investigated whether the association between shift work and headache was explained by potential mediators in terms of perceived stress, poor sleep and health behaviors., Methods: In this longitudinal study, we used questionnaire data (collected in 2007 and 2009) from civil servants and hospital employees from the PRISME study. 2952 individuals were available for the analyses of shift work and headache and 2272 individuals were available for the analyses of shift work and migraine. Headache was operationalized as the participants' experience of "being bothered by headache during the past 4 weeks". Migraine was operationalized as "ever being diagnosed with migraine by a medical doctor". We used binary logistic regression to compare shift workers with permanent day workers and adjusted for socio-demographic factors. In a subsequent step, we adjusted for potential mediators., Results: We found higher odds of unspecific headache (OR = 1.25; 95% CI 1.02-1.54) and migraine (OR = 1.72; 95% CI 1.04-2.86) among shift workers compared with day workers. Our results suggest that the effect of shift work on headache and migraine differ between men and women. Inclusion of potential mediators in the analyses did not attenuate the associations., Conclusion: Shift workers have higher risk of reporting being bothered by headache as well as reporting being diagnosed with migraine. Future research is needed to disentangle the underlying mechanisms with the aim of reducing headache related to occupational exposures.

Purpose: To determine the prospective relation between workplace violence and the risk of long-term sickness absence (LTSA), and study if work-unit social capital could buffer this effect. As an explorative analysis, the association between work-unit social capital and workplace violence is also tested., Methods: The study is based on the Well-being in HospitAL Employees (WHALE) cohort, including healthcare employees in Denmark. The study sample consisted of 30,044 employees nested within 2304 work-units. Exposure to workplace violence and threats of violence during the past 12 months was measured by self-report. Work-unit social capital was computed by aggregating the mean individual responses within work-units. LTSA was defined as one or more episodes of ≥ 29 consecutive sickness absence days initiated within 2 years following baseline., Results: Employees experiencing workplace violence had a higher risk of LTSA (OR = 1.55; 95% CI 1.39-1.72), but there was no evidence in support of work-unit social capital buffering the effect of workplace violence on LTSA (RERI = 0.24; 95%CI: - 0.36 to 0.84; p = 0.12 for multiplicative interaction). High compared to low work-unit social capital was associated with a lower prevalence of workplace violence (OR = 0.47; 95% CI 0.36-0.61)., Conclusion: There was a prospective association between workplace violence and LTSA, but work-unit social capital did not buffer this effect. Furthermore, the results revealed an inverse association between work-unit social capital and workplace violence. The findings indicate that  in order to effectively reduce LTSA, preventive interventions need to both prevent workplace violence and strengthen social capital.

Aim: The aim of the present study was to examine the bidirectional associations between subjective role ambiguity and role conflicts at work, respectively, and self-reported sleep 2 years later. In addition, we also examine whether sense of coherence (SOC) moderate or mediate the association between role stressors and poor sleep and between poor sleep and role stressors., Methods: We used questionnaire data collected in 2006 and 2008 from the Workplace Bullying and Harassment cohort. In 2006, 3363 responded to the questionnaire and in 2008 1671 responded. In total, 1569 participants responded in both 2006 and 2008 to the questions on role stressors (in terms of role ambiguity and role conflicts at work) and sleep problems in both 2006 and 2008. Sleep problems were assessed with the awakening index (AWI) and the disturbed sleep index (DSI). Moderation and mediation analyses of the association were estimated using structural equation modelling., Results: We found a prospective association between role stressors and sleep problems [beta values were 0.07 (95% CI 0.03-0.11) and 0.05 (CI 0.01-0.10) for DSI and AWI, respectively] when adjusting for sleep problems at baseline, age, sex, and life style factors (i.e. alcohol, smoking, and leisure time physical activity). SOC moderated the association showing that participants with lower SOC scores who reported higher role ambiguity reported sleep problems to a higher extent than participants with high SOC scores. SOC also mediated the association between role stressors and sleep problems. We also found support for sleep problems at baseline and role stressors 2 years later [DSI 0.04 (CI 0.00-0.08) and 0.15 (CI 0.09-0.21)] for role ambiguity and role conflicts, respectively. Similar results were observed for AWI., Conclusion: Subjective role stressors were prospectively associated with sleep problems. Yet, sleep problems could also prospectively predict subjective role stressors (i.e. reverse causation). The analyses also showed that SOC may be regarded as both a mediating and a moderating factor of the association between subjective role conflicts and poor sleep. We found that SOC moderated the prospective association so participants with low SOC report more sleep problems with subjective role conflicts compared to participants with high SOC. Finally, we also found SOC mediated the prospective association between subjective role stressors and sleep problems and the reverse association.