Protein differences between human trapezius and vastus lateralis muscles determined with a proteomic approach

Background: The trapezius muscle is a neck muscle that is susceptible to chronic pain conditions associated with repetitive tasks, commonly referred to as chronic work-related myalgia, hence making the trapezius a muscle of clinical interest. To provide a basis for further investigations of the proteomic traits of the trapezius muscle in disease, two-dimensional difference gel electrophoresis (2D-DIGE) was performed on the healthy trapezius using vastus lateralis as a reference. To obtain as much information as possible from the vast proteomic data set, both one-way ANOVA, with and without false discovery rate (FDR) correlation, and partial least square projection to latent structures with discriminant analysis (PLS-DA) were combined to compare the outcome of the analysis. Results: The trapezius and vastus lateralis showed significant differences in metabolic, contractile and regulatory proteins, with different results depending on choice of statistical approach and pre-processing technique. Using the standard method, FDR correlated one-way ANOVA, 42 protein spots differed significantly in abundance between the two muscles. Complementary analysis using immunohistochemistry and western blot confirmed the results from the 2D-DIGE analysis. Conclusions: The proteomic approach used in the present study combining 2D-DIGE and multivariate modelling provided a more comprehensive comparison of the protein profiles of the human trapezius and vastus lateralis muscle, than previously possible to obtain with immunohistochemistry or SDS-PAGE alone. Although 2D-DIGE has inherent limitations it is particularly useful to comprehensively screen for important structural and metabolic proteins, and appears to be a promising tool for future studies of patients suffering from chronic work related myalgia or other muscle diseases

Tillämpning av proteomiska och metabolomiska metoder på human skelettmuskel med inriktning mot kronisk trapezius myalgi

Work related musculoskeletal disorders are the dominating causes of reported ill-health in industrialized countries. These chronic pain conditions are one of the most costly public health problems in Europe and North America. When work related musculoskeletal disorders are considered to be of muscular origin and the trapezius muscle is affected, the common appellation is trapezius myalgia. Since little is known about the genesis or how it is maintained, it is of great importance to better understand the pathophysiology of trapezius myalgia; doing so will better enable recommendations for prevention, treatment and rehabilitation. Several hypotheses have been presented based on biochemical alterations in the muscle, suggesting increased signaling of inflammatory substances and altered metabolism. Previous research has not been able to present the comprehensive picture of the muscle in pain. Thus there is a demand for more comprehensive research regarding the biochemical milleu of the chronic trapezius muscle. Proteomic and metabolomic methods allow non-targeted simultaneous analyses of a large number of proteins and metabolites. The main emphasis in this thesis is on a proteomic method, two-dimensional differential gel electrophoresis (2D-DIGE). The method is validated to human skeletal muscle biopsy research with laboratory specific settings. In the baseline study, there were 14 metabolic, contractile, structural and regulatory proteins that differed significantly in abundance when trapezius and vastus lateralis muscles were compared. Using the validated 2D-DIGE method and the baseline study, a comparison between healthy and myalgic muscles was made. Biopsies from female cleaners with and without myalgia were compared to obtain results from women with the same type of work exposure. In the multivariate model, 28 identified unique proteins separated healthy and myalgic muscle and were grouped according to function: metabolic (n=10), contractile (n=9), regulatory (n=3), structural (n=4), and other (n=2). Finally, a second screening method, metabolomics, was introduced to analyze differences in metabolite content as a complement to and verification of the proteomic results. Gas chromatography-mass spectrometry (GC-MS) was performed on muscle interstitial fluid samples obtained with microdialysis, and differences in the abundance of extracellular metabolites were revealed.  The 2D-DIGE method is a reliable method to analyze human skeletal muscle. The outcomes of the proteomic analyses were dependant on the statistical approach. Systematic differences in protein and metabolite content were detected using a multivariate approach. Univariate analyses were used to analyze individual proteins for their significance. The significant proteins in the baseline study were predominately related to muscle fiber type which correlated with the differences in fiber type content between trapezius and vastus lateralis. The proteomic and metabolomics studies where myalgic and healthy muscles were compared provide us with new clues and new aspects regarding the pathophysiology of the myalgic muscle. Technically advanced methods employed in the thesis enabled an explorative screening of proteins of relevance for the pathophysiology of the myalgic muscle. The results of these analyses may contribute to the formulation of future hypothesis that need to be further evaluated

Dietary Fiber Intake among Normal-Weight and Overweight Female Health Care Workers : An Exploratory Nested Case-Control Study within FINALE-Health

Socioeconomic factors affect choice of diet, that is, dietary fiber intake. Underreporting of food consumption in diet surveys has been reported higher in low-income, low-education groups compared to high-income, high-education groups. This paper examines in a socioeconomic homogenous low-income low-education group of females the relation between dietary fiber intake and overweight and scrutinizes if the level of underreporting is equally large in normal-weight and overweight groups. Thirty-four female health care workers classified as either normal-weight () or obese () based on BMI, fat percentage, and waist circumference participated. A detailed food-diary was used to record their dietary intake in 9 days. Average dietary fiber intake in the normal-weight group was 2.73 +/− 0.65 g/MJ, while it was 2.15 +/− 0.64 g/MJ for the women in the obese group. In both groups, the overall food intake was underreported. In spite of a significantly lower dietary fiber intake in the obese group, the present population of women working within health care all showed an overall low dietary fiber intake and a general underreporting of food intake. These results indicate a clear need for dietary advice especially on fiber intake to increase general health and decrease weight

Multivariate Modeling of Proteins Related to Trapezius Myalgia, a Comparative Study of Female Cleaners with or without Pain

The prevalence of chronic trapezius myalgia is high in women with high exposure to awkward working positions, repetitive movements and movements with high precision demands. The mechanisms behind chronic trapezius myalgia are not fully understood. The purpose of this study was to explore the differences in protein content between healthy and myalgic trapezius muscle using proteomics. Muscle biopsies from 12 female cleaners with work-related trapezius myalgia and 12 pain free female cleaners were obtained from the descending part of the trapezius. Proteins were separated with two-dimensional differential gel electrophoresis (2D-DIGE) and selected proteins were identified with mass spectrometry. In order to discriminate the two groups, quantified proteins were fitted to a multivariate analysis: partial least square discriminate analysis. The model separated 28 unique proteins which were related to glycolysis, the tricaboxylic acid cycle, to the contractile apparatus, the cytoskeleton and to acute response proteins. The results suggest altered metabolism, a higher abundance of proteins related to inflammation in myalgic cleaners compared to healthy, and a possible alteration of the contractile apparatus. This explorative proteomic screening of proteins related to chronic pain in the trapezius muscle provides new important aspects of the pathophysiology behind chronic trapezius myalgia

Higher prevalence of type 2 diabetes in men than in women is associated with differences in visceral fat mass

Context: We have previously found that visceral fat is a stronger predictor for cardiovascular risk factors than body mass index (BMI). Objective: This study sought to investigate the prevalence of diabetes in elderly men and women in relation to objectively assessed visceral fat volume. Design and Setting: The cohort consisted of a population-based sample of 705 men and 688 women, all age 70 y at the time of examination. Main Outcome Measures: Associations between body fat estimates, plasma glucose level, and diabetes prevalence were investigated using multivariable-adjusted statistical models. Results: The prevalence of type 2 diabetes was 14.6% in men and 9.1% in women (P <.001). Mean BMIwasslightlyhigherinmenthaninwomen(27.3vs26.6kg/m2; P =.01),withagreaterdifference in mean visceral fat mass (1987 vs 1077 g; P <.001). After adjustment for physical activity and smoking, men had about/approximately twice the odds of having type 2 diabetes compared with women (odds ratio [OR], 1.95; 95% confidence interval [CI], 1.38-2.76). The inclusion of BMI in this model did not change the risk associated with male sex (OR, 1.93; 95% CI, 1.34-2.77). However, whenvisceralfatwasincludedasacovariate,malesexwasnotassociatedwithincreasedriskoftype 2 diabetes (OR, 0.77; 95% CI, 0.51-1.18). Conclusions: The higher prevalence of type 2 diabetes in older men than in older women was associated with larger amount of visceral fat in men. In contrast, differences in BMI was not associated with this difference

Serum Metabolites in Hand-Arm Vibration Exposed Workers

Objective: To investigate whether low molecular organic biomarkers could be identified in blood samples from vibration exposed workers using a metabolomics. Methods: The study population consisted of 38 metalworkers. All participants underwent a standardized medical examination. Blood samples were collected before and after work shift and analyzed with GC-TOFMS. Multivariate modeling (orthogonal partial least-squares analysis with discriminant analysis [OPLS-DA]) were used to verify differences in metabolic profiles. Results: Twenty-two study participants reported vascular symptoms judged as vibration-related. The metabolic profile from participants with vibration-induced white fingers (VWF) was distinctly separated from participants without VWF, both before and after vibration exposure. Conclusion: Metabolites that differed between the groups were identified both before and after exposure. Some of these metabolites might be indicators of health effects from exposure to vibrations. This is the first time that a metabolomic approach has been used in workers exposed to vibrations

Systemic differences in serum metabolome : a cross sectional comparison of women with localised and widespread pain and controls

Chronic musculoskeletal pain exists either as localised to a single region or as widespread to multiple sites in several quadrants of the body. Prospective studies indicate that widespread pain could act as a far end of a continuum of musculoskeletal pain that started with chronic localised pain. The mechanism by which the transition from localised pain to widespread occurs is not clear, although many studies suggest it to be an altered metabolism. In this study, systemic metabolic differences between women with chronic localised neck-shoulder pain (NP), women with chronic widespread pain (CWP) and women who were healthy (CON) were assessed. Blood samples were analysed taking a metabolomics approach using gas chromatography mass spectrometry (GC-MS) and orthogonal partial least square discriminant analysis (OPLS-DA). The metabolomics analysis showed a clear systematic difference in the metabolic profiles between the subjects with NP and the CON but only a weak systematic difference between the subjects with CWP and the CON. This most likely reflects a difference in the portion of the metabolome influenced by the two pain conditions. In the NP group, the overall metabolic profile suggests that processes related to energy utilisation and lipid metabolism could be central aspects of mechanisms maintaining disorder

Background, design and conceptual model of the cluster randomized multiple-component workplace study: FRamed Intervention to Decrease Occupational Muscle pain - "FRIDOM"

Abstract Background Several RCT studies have aimed to reduce either musculoskeletal disorders, sickness presenteeism, sickness absenteeism or a combination of these among females with high physical work demands. These studies have provided evidence that workplace health promotion (WHP) interventions are effective, but long-term effects are still uncertain. These studies either lack to succeed in maintaining intervention effects or lack to document if effects are maintained past a one-year period. This paper describes the background, design and conceptual model of the FRIDOM (FRamed Intervention to Decrease Occupational Muscle pain) WHP program among health care workers. A job group characterized by having high physical work demands, musculoskeletal disorders, high sickness presenteeism - and absenteeism. Methods FRIDOM aimed to reduce neck and shoulder pain. Secondary aims were to decrease sickness presenteeism, sickness absenteeism and lifestyle-diseases such as other musculoskeletal disorders as well as metabolic-, and cardiovascular disorders – and to maintain participation to regular physical exercise training, after a one year intervention period. The entire concept was tailored to a population of female health care workers. This was done through a multi-component intervention including 1) intelligent physical exercise training (IPET), dietary advice and weight loss (DAW) and cognitive behavioural training (CBT). Discussion The FRIDOM program has the potential to provide evidence-based knowledge of the pain reducing effect of a multi component WHP among a female group of employees with a high prevalence of musculoskeletal disorders and in a long term perspective evaluate the effects on sickness presenteeism and absenteeism as well as risk of life-style diseases. Trial registration NCT02843269 , 06.27.2016 - retrospectively registered

Work-Related Stress Was Not Associated with Increased Cancer Risk in a Population-Based Cohort Setting

Background: Stress is a commonly perceived cause of cancer, but the evidence to date is limited and inconclusive. We examined work-related stress in relation to cancer incidence in a population-based cohort, with outcome data from Swedish national registries. Methods: The study population included 113,057 participants in the Västerbotten Intervention Programme. HRs were estimated using Cox proportional hazards regression, for cancer overall and for types with ≥500 cases, and adjusting for several potential confounders. The primary exposure was prediagnostic work-related stress, using the well established Karasek job demand/control model. Demand and control variables were dichotomized at the median, and participants were classified according to combinations of these categories. We also considered social network and aspects of quality of life. Results: "High-strain" work (high demand/low control) was not associated with cancer risk compared with "low-strain" work (low demand/high control): multivariable HR 1.01 [95% confidence interval (CI), 0.94-1.08] for men and 0.99 (95% CI, 0.92-1.07) for women. Results were also null for most cancer types assessed: prostate, breast, colorectal, lung, and gastrointestinal (GI). The risk of GI cancer was lower for "passive" (low demand/low control) versus "low-strain" work, particularly for colorectal cancer in women: multivariable HR 0.71 (95% CI, 0.55-0.91), but statistical significance was lost after adjustment for multiple testing. Conclusions: The findings of this population-based, cohort study do not support a role for work-related stress in determining cancer risk. Impact: This study helps fill an important knowledge gap given the common concern about stress as a risk factor for cancer

Plasma metabolomic patterns in patients with exhaustion disorder

Exhaustion disorder (ED) is a stress-related disorder that often implies a great burden on the individual patient as well as on society. Previous studies have shown that ED is associated with metabolic deviations, such as lowered fasting glucose. Several mechanisms have been discussed as a plausible explanation of the lack of energy described by these patients. Metabolic processes and reduced ability to mobilize energy have been suggested as important factors. This study investigated metabolomics in 20 patients diagnosed with ED and compared them with 21 healthy controls. Plasma metabolic profiles were examined in both fasting and nonfasting (postprandial) conditions. Blood plasma samples were analyzed for metabolite content using gas chromatography mass spectrometry. A total of 62 different metabolites were simultaneously detected in each of the samples. Multivariate models indicated systematic differences between patients with ED and healthy controls in both their fasting and nonfasting plasma metabolite levels. Lysine and octadecenoic acid were more abundant and glutamine, glycine, serine and gluconic acid were less abundant in the patients across both conditions. In the present study, we comprehensively and simultaneously screen for changes in a large number of metabolites. Our results show a difference in systemic metabolites between patients with exhaustion disorder and healthy controls both in the fasting and in the postprandial states. Here, we present new potential biomarkers mirroring exhaustion disorder metabolism