Ligaments: a source of work-related musculoskeletal disorders.

The mechanical and neurological properties of ligaments are reviewed and updated with recent development from the perspective which evaluates their role as a source of neuromusculoskeletal disorders resulting from exposure to occupational activities. Creep, tension-relaxation, hysteresis, sensitivity to strain rate and strain/load frequency were shown to result not only in mechanical functional degradation but also in the development of sensory-motor disorders with short- and long-term implication on function and disability. The recently exposed relationships between collagen fibers, applied mechanical stimuli, tissue microdamage, acute and chronic inflammation and neuromuscular disorders is delineated with special reference to occupational stressors.     

Work activities of practical nurses and risk factors for the development of musculoskeletal disorders

Musculoskeletal and emotional disorders are important causes of reported diseases, causing medical absences, and eventually earlier decrease of work ability. This paper reports the results of a study carried out among practical nurses working at the Orthopedics and Trauma Institute. The objectives of the study were: (a) to describe the routine activities performed during day and night shifts, and (b) to compare the work activities performed in different wards during these shifts. A Brazilian version of the Work Ability Index--WAI (TUOMI et al., 1994) was answered by 83 practical nurses. Forty-three of them (52%) reported pains or musculoskeletal diseases, either based on their own opinion or diagnosed by a physician. These nurses were invited to join the second phase of the study and twenty-nine accepted it. All work activities performed in 29 shifts were observed and recorded. The results showed that day shifts were far more demanding in terms of the number of activities related to patients' care than afternoon and night shifts. Also, body postures associated with day work activities demanded important physical efforts. The number of nurses in charge during night shifts was substantially lower than during day shifts. This could lead to an overload and affect the health of the nurses.     

Work-related musculoskeletal disorders: the epidemiologic evidence and the debate.

The debate about work-relatedness of musculoskeletal disorders (MSDs) reflects both confusion about epidemiologic principles and gaps in the scientific literature. The physical ergonomic features of work frequently cited as risk factors for MSDs include rapid work pace and repetitive motion, forceful exertions, non-neutral body postures, and vibration. However, some still dispute the importance of these factors, especially relative to non-occupational causes. This paper addresses the controversy with reference to a major report recently commissioned by the US Congress from the National Research Council (NRC) and Institute of Medicine (IOM) (2001). The available epidemiologic evidence is substantial, but will benefit from more longitudinal data to better evaluate gaps in knowledge concerning latency of effect, natural history, prognosis, and potential for selection bias in the form of the healthy worker effect. While objective measures may be especially useful in establishing a more secure diagnosis, subjective measures better capture patient impact. Examination techniques still do not exist that can serve as a "gold standard" for many of the symptoms that are commonly reported in workplace studies. Finally, exposure assessment has too often been limited to crude indicators, such as job title. Worker self-report, investigator observation, and direct measurement each add to understanding but the lack of standardized exposure metrics limits ability to compare findings among studies. Despite these challenges, the epidemiologic literature on work-related MSDs-in combination with extensive laboratory evidence of pathomechanisms related to work stressors-is convincing to most. The NRC/IOM report concluded, and other reviewers internationally have concurred, that the etiologic importance of occupational ergonomic stressors for the occurrence of MSDs of the low back and upper extremities has been demonstrated.     

Interventions to reduce work-related musculoskeletal disorders.

Work-related Musculoskeletal Disorders (WMSDs) continue to present a major challenge to workers and their employers in virtually every industry sector. Many disciplines have been involved in providing advice and working on interventions to prevent WMSDs or reduce their consequences. Since the early 1990s, 15 systematic reviews (excluding specific treatment modalities) have appeared in the peer-reviewed literature addressing musculoskeletal disorder reduction. The National Research Council-Institute of Medicine summarized many of these efforts in 2001. Using a systematic literature search strategy, we identified 20 randomized controlled studies, 17 quasi-experimental studies with control groups, and 36 paper reporting case studies with in the peer-reviewed literature between 1999-2003. Evidence is continuing to build that demonstrates combinations of measures appear to have the greatest effect in reducing WMSDs, although individual engineering and administrative controls can also have positive effects.     

Surface EMG recordings and pain-related disorders: a diagnostic framework

Surface electromyography provides a very valuable set of information when used diagnostically with pain-related disorders. Unfortunately, most researchers and clinicians limit their investigation to only one level of diagnostic information available concerning the neuromuscular system. This article develops and encourages the clinician/researcher to consider three levels of diagnostic information: emotional, organ-related, and postural aspects. The theoretical background and diagnostic procedures used to investigate each is presented. Differential treatment considerations, given differential diagnostic findings, are discussed.     

Following the genes: a framework for animal modeling of psychiatric disorders

Background

The caspase family, which plays a central role in apoptosis in metazoans, has undergone an expansion in amphioxus, increasing to 45 members through domain recombination and shuffling.

Results

In order to shed light on the conservation and uniqueness of this family in amphioxus, we cloned three representative caspase genes, designated as bbtCaspase-8, bbtCaspase-1/2 and bbtCaspase3-like, from the amphioxus Branchiostoma belcheri tsingtauense. We found that bbtCaspase-8 with conserved protein architecture is involved in the Fas-associated death domain-Caspase-8 mediated pro-apoptotic extrinsic pathway, while bbtCaspase3-like may mediate a nuclear apoptotic pathway in amphioxus. Also, bbtCaspase-1/2 can co-localize with bbtFADD2 in the nucleus, and be recruited to the cytoplasm by amphioxus apoptosis associated speck-like proteins containing a caspase recruitment domain, indicating that bbtCaspase-1/2 may serve as a switch between apoptosis and caspase-dependent innate immune response in invertebrates. Finally, amphioxus extrinsic apoptotic pathway related caspases played important roles in early embryogenesis.

Conclusions

Our study not only demonstrates the conservation of bbtCaspase-8 in apoptosis, but also reveals the unique features of several amphioxus caspases with novel domain architectures arose some 500 million years ago.     

INDI: a computational framework for inferring drug interactions and their associated recommendations

Inferring drug–drug interactions (DDIs) is an essential step in drug development and drug administration. Most computational inference methods focus on modeling drug pharmacokinetics, aiming at interactions that result from a common metabolizing enzyme (CYP). Here, we introduce a novel prediction method, INDI (INferring Drug Interactions), allowing the inference of both pharmacokinetic, CYP‐related DDIs (along with their associated CYPs) and pharmacodynamic, non‐CYP associated ones. On cross validation, it obtains high specificity and sensitivity levels (AUC (area under the receiver‐operating characteristic curve)?0.93). In application to the FDA adverse event reporting system, 53% of the drug events could potentially be connected to known (41%) or predicted (12%) DDIs. Additionally, INDI predicts the severity level of each DDI upon co‐administration of the involved drugs, suggesting that severe interactions are abundant in the clinical practice. Examining regularly taken medications by hospitalized patients, 18% of the patients receive known or predicted severely interacting drugs and are hospitalized more frequently. Access to INDI and its predictions is provided via a web tool at http://www.cs.tau.ac.il/～bnet/software/INDI , facilitating the inference and exploration of drug interactions and providing important leads for physicians and pharmaceutical companies alike.     

A system for predicting and preventing work-related musculoskeletal disorders among dentists

Work-related musculoskeletal disorders (WMSDs) have become increasingly common among dentists and initiate a series of events that could result in a career ending. This study aims to construct a system for predicting and preventing WMSD among dentists. We used Bayesian network (BN) that describes the mutual relationships among multiple variables contributing to WMSDs. The data-sets were prepared from direct measurements of dentist's movements and a questionnaire survey. We applied BN learning algorithms to the training data-sets to develop WMSD prediction model using 10-fold cross-validation. To evaluate the system performance, 16 dentists were randomly assigned into a 2 × 2 crossover trial scheduled to each of two sequences of dental working: receiving feedback or no feedback including the probability of WMSD and related risk factors from the system. The group that received feedback decreased significantly (t-test, p < 0.05) the extensions of neck and upper back in the y-axis as well as the WMSD probability on the post-test. In conclusion, the system for predicting and preventing WMSD aids the correction of neck and upper back extensions and reduction in WMSD probability, which may potentially contribute to reduce the risk of WMSD among dentists.     

Mechanisms of central sensitization, neuroimmunology & injury biomechanics in persistent pain: implications for musculoskeletal disorders.

This review will offer an overview of the mechanistic pathways of chronic pain associated with musculoskeletal disorders (MSDs). Traditional electrophysiological pain pathways of these injuries will be reviewed. In addition, recent research efforts in persistent pain have characterized a cascade of neuroimmunologic events in the central nervous system that manifests in pain behaviors and neurochemical nociceptive responses. Physiologic changes in the central nervous system will be covered as they pertain to the interplay of these two areas, and also as they focus on MSDs and injuries. One such injury leading to persistent pain is radiculopathy, which results from nerve root compression or impingement and leads to low back pain. This painful syndrome will be used as an example to provide a context for presenting immune mechanisms of chronic pain and their relationship to injury. Measures of injury biomechanics are presented in the context of the resulting pain responses, including behavioral sensitivity, local structural changes, and cellular and molecular changes in the CNS. Lastly, based on these findings and others, a discussion is provided highlighting areas of future work to help elucidate methods of injury diagnosis and development of therapeutic treatments.     

Reducing the costs of work-related musculoskeletal disorders: targeting strategies to chronic disability cases.

Musculoskeletal disorders impose a significant direct cost burden on health care systems in the US and Canada and account for even greater indirect losses of productivity. The overall prevalence of musculoskeletal disorders is high, but a disproportionate share of costs is associated with a small number of cases with chronic pain. This is especially true for cases of occupational back pain, the single most common and costly musculoskeletal disorder in the workplace. A number of studies identify workplace characteristics associated with prolonged disability among cases of work-related back pain. These characteristics include: failure to receive job accommodations, receipt of disability benefit payments, and employment in high-risk industries or jobs that require heavy lifting. Research on the predictors of high-cost cases is limited, however, because of the lack of high-quality data and the need for a multidisciplinary approach. A new study, the Arizona State University Healthy Back Study, addresses some of these issues and promises new insights into effective strategies to reduce the proportion of high-cost claims.     

CoagVDb: a comprehensive database for coagulation factors and their associated SAPs

The current state of the art in medical genetics is to identify and classify the functional (deleterious) or non-functional (neutral) single amino acid substitutions (SAPs), also known as non-synonymous SNPs (nsSNPs). The primary goal is to elucidate the mechanisms through which functional SAPs exert their effects, and ultimately interrogating this information for association with complex phenotypes. This work focuses on coagulation factors involved in the coagulation cascade pathway which plays a vital role in the maintenance of homeostasis in the human system. We developed an integrated coagulation variation database, CoagVDb, which makes use of the biological information from various public databases such as NCBI, OMIM, UniProt, PDB and SAPs (rsIDs/variant). CoagVDb enriched with computational prediction scores classify SAPs as either deleterious or tolerated. Also, various other properties are incorporated such as amino acid composition, secondary structure elements, solvent accessibility, ordered/disordered regions, conservation, and the presence of disulfide bonds. This specialized database provides integration of various prediction scores from different computational methods along with gene, protein, and disease information. We hope our database will act as a useful reference resource for hematologists to reveal protein structure–function relationship and disease genotype–phenotype correlation.

Electronic supplementary material

The online version of this article (doi:10.1186/s40659-015-0028-5) contains supplementary material, which is available to authorized users.     

Individual and occupational risk factors for knee osteoarthritis: results of a case-control study in Germany

Introduction

A number of occupational risk factors are discussed in relation to the development and progress of knee joint diseases (for example, working in a kneeling or squatting posture, lifting and carrying heavy weights). Besides the occupational factors, a number of individual risk factors are important. The distinction between work-related and other factors is crucial in assessing the risk and in deriving preventive measures in occupational health.

Methods

In a case-control study, patients with and without symptomatic knee osteoarthritis (OA) were questioned by means of a standardised questionnaire complemented by a semi-standardised interview. Controls were matched and assigned to the cases by gender and age. Conditional logistic regression was used in analysing data.

Results

In total, 739 cases and 571 controls were included in the study. In women and men, several individual and occupational predictors for knee OA could be described: obesity (odds ratio (OR) up to 17.65 in women and up to 12.56 in men); kneeling/squatting (women, OR 2.52 (>8,934 hours/life); men, 2.16 (574 to 12,244 hours/life), 2.47 (>12,244 hours/life)); genetic predisposition (women, OR 2.17; men, OR 2.37); and sports with a risk of unapparent trauma (women, OR 2.47 (≥1,440 hours/life); men, 2.58 (≥3,232 hours/life)). In women, malalignment of the knee (OR 11.54), pain in the knee already in childhood (OR 2.08), and the daily lifting and carrying of loads (≥1,088 tons/life, OR 2.13) were related to an increased OR; sitting and smoking led to a reduced OR.

Conclusions

The results support a dose-response relationship between kneeling/squatting and symptomatic knee OA in men and, for the first time, in women. The results concerning general and occupational predictors for knee OA reflect the findings from the literature quite well. Yet occupational risks such as jumping or climbing stairs/ladders, as discussed in the literature, did not correlate with symptomatic knee OA in the present study. With regards to occupational health, prevention measures should focus on the reduction of kneeling activities and the lifting and carrying of loads as well as general risk factors, most notably the reduction of obesity. More intervention studies of the effectiveness of tools and working methods for reducing knee straining activities are needed.     

A general-purpose framework to simulate musculoskeletal system of human body: using a motion tracking approach*

Computation of muscle force patterns that produce specified movements of muscle-actuated dynamic models is an important and challenging problem. This problem is an undetermined one, and then a proper optimization is required to calculate muscle forces. The purpose of this paper is to develop a general model for calculating all muscle activation and force patterns in an arbitrary human body movement. For this aim, the equations of a multibody system forward dynamics, which is considered for skeletal system of the human body model, is derived using Lagrange–Euler formulation. Next, muscle contraction dynamics is added to this model and forward dynamics of an arbitrary musculoskeletal system is obtained. For optimization purpose, the obtained model is used in computed muscle control algorithm, and a closed-loop system for tracking desired motions is derived. Finally, a popular sport exercise, biceps curl, is simulated by using this algorithm and the validity of the obtained results is evaluated via EMG signals.     

Multi-node graphs: a framework for multiplexed biological assays.

Multiplex polymerase chain reaction (PCR) is an extension of the standard PCR protocol in which primers for multiple DNA loci are pooled together within a single reaction tube, enabling simultaneous sequence amplification, thus reducing costs and saving time. Potential cost saving and throughput improvements directly depend on the level of multiplexing achieved. Designing reliable and highly multiplexed assays is challenging because primers that are pooled together in a single reaction tube may cross-hybridize, though this can be addressed either by modifying the choice of primers for one or more amplicons, or by altering the way in which DNA loci are partitioned into separate reaction tubes. In this paper, we introduce a new graph formalism called a multi-node graph, and describe its application to the analysis of multiplex PCR scalability. We show, using random multi-node graphs that the scalability of multiplex PCR is constrained by a phase transition, suggesting fundamental limits on efforts to improve the cost-effectiveness and throughput of standard multiplex PCR assays. In particular, we show that when the multiplexing level of the reaction tubes is roughly theta(log (sn)) (where s is the number of primer pair candidates per locus and n is the number of loci to be amplified), then with very high probability we can 'cover' all loci with a valid assignment to one of the tubes in the assay. However, when the multiplexing level of the tube exceeds these bounds, there is no possible cover and moreover the size of the cover drops dramatically. Simulations using a simple greedy algorithm on real DNA data also confirm the presence of this phase transition. Our theoretical results suggest, however, that the resulting phase transition is a fundamental characteristic of the problem, implying intrinsic limits on the development of future assay design algorithms.     

Relationships between physical activity and musculoskeletal disorders in former athletes

The purpose of the study was to determine the prevalence and risks for musculoskeletal disorders (MSD) in relation to previous athletic status and current physical activity level in former athletes. Main anthropometric data, sports history, current physical activity and MSD were estimated using a questionnaire in 219 (148 males, 71 females) former athletes (35-75 years old) and 79 controls (33 males, 46 females). According to the previous participation in top-level sports, former athletes were divided into three groups: (a) endurance, n=120 (76 males, 44 females); (b) speed-power, n=57 (43 males, 14 females); (c) team sports, n=42 (29 males, 13 females). The most prevalent MSD among the male and female ex-athletes were back and knee pain. The endurance ex-athletes group (both males and females) had significantly higher risk for the knee problems than the control group (Odds ratio--OR 5.9, 95% CI 1.7-20.00, p < 0.05). Team sports athletes (males and females) showed significantly higher risk for Achilles' tendon injuries (OR 3.19 95% CI 1.19-8.5, p < 0.05) as compared to controls. Back pain did not show any significant associations with previous physical activity and current physical activity level. Current physical activity was significantly associated with a lower risk for the knee and hip pain. Body mass index was positively associated with knee problems. In conclusion, our study results revealed that previous participation in enduranve sports events is associated with a significantly higher risk for knee problems. At the same time current regular physical exercise 6-11 times per month is associated with a lower prevalence of knee and hip problems as compared to those who exercised less than 6 times per month.