Jenny Hadrévi

Comparative metabolomics of muscle interstitium fluid in human trapezius myalgia: an in vivo microdialysis study

PurposeThe mechanisms behind trapezius myalgia are unclear. Many hypotheses have been presented suggesting an altered metabolism in the muscle. Here, muscle microdialysate from healthy and myalgic muscle is analysed using metabolomics. Metabolomics analyse a vast number of metabolites, enabling a comprehensive explorative screening of the cellular processes in the muscle.MethodsMicrodialysate samples were obtained from the shoulder muscle of healthy and myalgic subjects that performed a work and stress test. Samples from the baseline period and from the recovery period were analysed using gas chromatography—mass spectrometry (GC–MS) together with multivariate analysis to detect differences in extracellular content of metabolites between groups. Systematic differences in metabolites between groups were identified using multivariate analysis and orthogonal partial least square discriminate analysis (OPLS-DA). A complementary Mann–Whitney U test of group difference in individual metabolites was also performed.ResultsA large number of metabolites were detected and identified in this screening study. At baseline, no systematic differences between groups were observed according to the OPLS-DA. However, two metabolites, l-leucine and pyroglutamic acid, were significantly more abundant in the myalgic muscle compared to the healthy muscle. In the recovery period, systematic difference in metabolites between the groups was observed according to the OPLS-DA. The groups differed in amino acids, fatty acids and carbohydrates. Myristic acid and putrescine were significantly more abundant and beta-d-glucopyranose was significantly less abundant in the myalgic muscle.ConclusionThis study provides important information regarding the metabolite content, thereby presenting new clues regarding the pathophysiology of the myalgic muscle.

Evaluation of 2‐D DIGE for skeletal muscle: Protocol and repeatability

Proteomic analysis has the potential to yield vast amounts of data. The available proteomic methods have been hampered by methodological errors in quantification due to large gel‐to‐gel variations. The inclusion of an internal standard greatly reduces this variation, and therefore the purpose of this investigation was: 1) to develop a sample preparation protocol for human skeletal muscle for two‐dimensional differentiated gel electrophoresis (DIGE) and 2) to investigate the repeatability of one particular system, the Ettan™ DIGE. To test repeatability, nine aliquots from the same homogenate were labelled with three different CyDye™ dyes (Cy2, Cy3, Cy5). Samples were run on 18×24 cm gels, scanned with a Typhoon™ 9410 laser scanner and analysed in the DeCyder™ software. When selecting spots appearing only in triplicate (n = 1314), the mean error was 1.7 % (SD: 10.5 %; 95 % CI: 1.1–2.4 %). When setting the significance level to 99 %, no false‐positive changes in protein volume ratios were detected. In the protocol presented here, only 0.5 mg tissue was used and separation of >2500 distinct protein spots in the pH range 3–11 and MW 10–200 kDa. Changes in protein abundance of <20 % could be detected. The method is especially useful when comparing muscle proteins between different conditions; for example, healthy and diseased tissue, before and after treatment or different exercise protocols.

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.

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

BackgroundThe 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.ResultsThe 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.ConclusionsThe 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.

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"

BackgroundSeveral 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.MethodsFRIDOM 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).DiscussionThe 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 registrationNCT02843269, 06.27.2016 - retrospectively registered.

Sickness behaviors (reduced social interaction and pain behaviors) are linked to inflammatory mechanisms in a rat model of work-related musculoskeletal disorders

We sought to determine if sickness behaviors (decreased social interaction and pain) are induced in a rat model of work-related overuse and effectiveness of anti-inflammatory treatments. Rats first trained to learn a high force reaching task (15 min/week day for 6 wks), with subsets treated prophylactically with ibuprofen or anti-TNFalpha. Others performed a high repetition high force (HRHF) task for 6 or 12 weeks (2 hrs/day, 3 days/wk) untreated, or with ibuprofen, anti-TNFalpha or rest treatments beginning task week 5. Untreated HRHF rats had increased IL-1beta, IL-6 and TNFalpha in serum and brain, increased Substance P in spinal cord, decreased social interaction and increased forepaw allodynia. Secondary anti-inflammatory treatments attenuated social interaction and brain changes, but not allodynia or spinal cord changes; rest provided partial attenuation. Prophylactic treatments prevented all changes. Thus, inflammatory mechanisms mediate the development of sickness behaviors induced by work-related overuse, but not maintenance of allodynia.

New Aspects on Chronic Trapezius Myalgia: Contribution of Metabolomics and Proteomics

Abstract Several hypotheses regarding the underlying mechanisms and the maintenance behind chronic work-related musculoskeletal disorders have been presented. Chronic low load work and psychosocial stress is believed to be the underlying causes to these pain conditions. The recent application of comprehensive screening methods: omnics methods; to this field of research could contribute to current knowledge regarding the pathophysiology of these disorders. The pathophysiological mechanisms behind chronic trapezius myalgia are discussed in the context of new findings obtained with proteomic and metabolomic methods. Proteins and metabolites which differ in abundance between healthy muscle and muscle suffering from chronic trapezius myalgia are presented. Primarily, the pathways and effects of the proteins and metabolites found in three recently published papers are discussed. Proteomics and metabolomics are efficient screening methods enabling the presentation of potential biomarkers and pathophysiological mechanisms explaining the pathophysiology of chronic work-related trapezius myalgia. The previous findings detecting systematic differences of proteins and metabolites when comparing chronic myalgic muscle to healthy muscle, indicating a higher glycogen metabolism, increased muscle turnover and increased neuronal signalling in the myalgic muscle, are discussed in this review.

Plasma metabolomic patterns in patients with exhaustion disorder

Abstract 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. Lay summary Exhaustion disorder (ED) patients suffer from stress-related symptoms including a reduced energy level. This study investigates the body’s metabolism in patients with ED, both fasting and after a meal. New potential markers that may help future investigations on ED were identified.

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 (N = 18) or obese (N = 16) 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.