60 research outputs found
Attenuation of muscle atrophy in a murine model of cachexia by inhibition of the dsRNA-dependent protein kinase
Atrophy of skeletal muscle is due to a depression in protein synthesis and an increase in degradation. Studies in vitro have suggested that activation of the dsRNA-dependent protein kinase (PKR) may be responsible for these changes in protein synthesis and degradation. In order to evaluate whether this is also applicable to cancer cachexia the action of a PKR inhibitor on the development of cachexia has been studied in mice bearing the MAC16 tumour. Treatment of animals with the PKR inhibitor (5βmgβkgβ1) significantly reduced levels of phospho-PKR in muscle down to that found in non-tumour-bearing mice, and effectively attenuated the depression of body weight, with increased muscle mass, and also inhibited tumour growth. There was an increase in protein synthesis in skeletal muscle, which paralleled a decrease in eukaryotic initiation factor 2Ξ± phosphorylation. Protein degradation rates in skeletal muscle were also significantly decreased, as was proteasome activity levels and expression. Myosin levels were increased up to values found in non-tumour-bearing animals. Proteasome expression correlated with a decreased nuclear accumulation of nuclear factor-ΞΊB (NF-ΞΊB). The PKR inhibitor also significantly inhibited tumour growth, although this appeared to be a separate event from the effect on muscle wasting. These results suggest that inhibition of the autophosphorylation of PKR may represent an appropriate target for the attenuation of muscle atrophy in cancer cachexia
Factors influencing quality of life following lower limb amputation for peripheral arterial occlusive disease: a systematic review of the literature
Background: The majority of lower limb amputations are undertaken in people with peripheral arterial occlusive disease,\ud
and approximately 50% have diabetes. Quality of life is an important outcome in lower limb amputations; little is known\ud
about what influences it, and therefore how to improve it.\ud
Objectives: The aim of this systematic review was to identify the factors that influence quality of life after lower limb\ud
amputation for peripheral arterial occlusive disease.\ud
Methods: MEDLINE, EMBASE, CINAHL, PsycINFO, Web of Science and Cochrane databases were searched to identify\ud
articles that quantitatively measured quality of life in those with a lower limb amputation for peripheral arterial occlusive\ud
disease. Articles were quality assessed by two assessors, evidence tables summarised each article and a narrative\ud
synthesis was performed.\ud
Study design: Systematic review.\ud
Results: Twelve articles were included. Study designs and outcome measures used varied. Quality assessment scores\ud
ranged from 36% to 92%. The ability to walk successfully with a prosthesis had the greatest positive impact on quality\ud
of life. A trans-femoral amputation was negatively associated with quality of life due to increased difficulty in walking\ud
with a prosthesis. Other factors such as older age, being male, longer time since amputation, level of social support and\ud
presence of diabetes also negatively affected quality of life.\ud
Conclusion: Being able to walk with a prosthesis is of primary importance to improve quality of life for people with lower\ud
limb amputation due to peripheral arterial occlusive disease. To further understand and improve the quality of life of this\ud
population, there is a need for more prospective longitudinal studies, with a standardised outcome measure
'Being there' for women with metastatic breast cancer: a pan-European patient survey
BACKGROUND: Understanding their experiences of diagnosis is integral to improving the quality of care for women living with advanced/metastatic breast cancer. METHODS: A survey, initiated in March 2011, was conducted in two stages. First, the views of 47 breast cancer-related patient groups in eight European countries were sought on standards of breast cancer care and unmet needs of patients. Findings were used to develop a patient-centric survey to capture personal experiences of advanced breast cancer to determine insights into the βtrade-off' between extending overall survival and side effects associated with its treatment. The second online survey was open to women with locally advanced or metastatic breast cancer, or their carers, and responders were recruited through local patient groups. Data were collected via anonymous local language questionnaires. RESULTS: The online stage II survey received a total of 230 responses from 17 European countries: 94% of respondents had locally advanced or metastatic breast cancer and 6% were adult carers. Although the overall experience of care was generally good/excellent (77%), gaps were still perceived in terms of treatment choice and information provision. Treatment choice for patients was felt to be lacking by 32% of responders. In addition, 68% of those who responded would have liked more information about future medical treatments and research, with 57% wishing to receive this information from their oncologist. Two-thirds (66%) of women with advanced breast cancer, or their carers, believed life-extending treatment to be important so that they can spend more time with family and friends, and 67% said that the treatment was worthwhile, despite potential associated side effects. CONCLUSION: These findings show a continuing need to provide women with advanced breast cancer with better information and emphasise the importance that these patients often place on prolonging survival
Revisiting the symptom iceberg in today's primary care: results from a UK population survey
Peer reviewedPublisher PD
In vitro assessment of the combined effect of eicosapentaenoic acid, green tea extract and curcumin C3 on protein loss in C2C12 myotubes
EPA has been clinically shown to reduce muscle wasting during cancer cachexia. This study investigates whether curcumin or green tea extract (GTE) enhances the ability of low doses of eicosapentaenoic acid (EPA) to reduce loss of muscle protein in an in vitro model. A low dose of EPA with minimal anti-cachectic activity was chosen to evaluate any potential synergistic effect with curcumin or GTE. Depression of protein synthesis and increase in degradation was determined in C2C12 myotubes in response to tumour necrosis factor-Ξ± (TNF-Ξ±) and proteolysis-inducing factor (PIF). EPA (50 ΞΌM) or curcumin (10 ΞΌg mlβ1) alone had little effect on protein degradation caused by PIF but the combination produced complete inhibition, as did the combination with GTE (10 ΞΌg mlβ1). In response to TNF-Ξ± (25 ng mlβ1)-induced protein degradation, EPA had a small, but not significant effect on protein degradation; however, when curcumin and GTE were combined with EPA, the effect was enhanced. EPA completely attenuated the depression of protein synthesis caused by TNF-Ξ±, but not that caused by PIF. The combination of EPA with curcumin produced a significant increase in protein synthesis to both agents. GTE alone or in combination with EPA had no effect on the depression of protein synthesis by TNF-Ξ±, but did significantly increase protein synthesis in PIF-treated cells. Both TNF-Ξ± and PIF significantly reduced myotube diameter from 17 to 13 ΞΌm for TNF-Ξ± (23.5%) and 15 ΞΌm (11.8%) for PIF However the triple combination of EPA, curcumin and GTE returned diameters to values not significantly different from the control. These results suggest that either curcumin or GTE or the combination could enhance the anti-catabolic effect of EPA on lean body mass
NF-ΞΊB mediates proteolysis-inducing factor induced protein degradation and expression of the ubiquitinβproteasome system in skeletal muscle
Loss of skeletal muscle in cancer cachexia has a negative effect on both morbidity and mortality. The role of nuclear factor-ΞΊB (NF-ΞΊB) in regulating muscle protein degradation and expression of the ubiquitinβproteasome proteolytic pathway in response to a tumour cachectic factor, proteolysis-inducing factor (PIF), has been studied by creating stable, transdominant-negative, muscle cell lines. Murine C2C12 myoblasts were transfected with plasmids with a CMV promoter that had mutations at the serine phosphorylation sites required for degradation of I-ΞΊBΞ±, an NF-ΞΊB inhibitory protein, and allowed to differentiate into myotubes. Proteolysis-inducing factor induced degradation of I-ΞΊBΞ±, nuclear accumulation of NF-ΞΊB and an increase in luciferase reporter gene activity in myotubes containing wild-type, but not mutant, I-ΞΊBΞ± proteins. Proteolysis-inducing factor also induced total protein degradation and loss of the myofibrillar protein myosin in myotubes containing wild-type, but not mutant, plasmids at the same concentrations as those causing activation of NF-ΞΊB. Proteolysis-inducing factor also induced increased expression of the ubiquitinβproteasome pathway, as determined by βchymotrypsin-like' enzyme activity, the predominant proteolytic activity of the Ξ²-subunits of the proteasome, protein expression of 20S Ξ±-subunits and the 19S subunits MSS1 and p42, as well as the ubiquitin conjugating enzyme, E214k, in cells containing wild-type, but not mutant, I-ΞΊBΞ±. The ability of mutant I-ΞΊBΞ± to inhibit PIF-induced protein degradation, as well as expression of the ubiquitinβproteasome pathway, confirms that both of these responses depend on initiation of transcription by NF-ΞΊB
Metabolic and morphological alterations induced by proteolysis-inducing factor from Walker tumour-bearing rats in C2C12 myotubes
BACKGROUND: Patients with advanced cancer suffer from cachexia, which is characterised by a marked weight loss, and is invariably associated with the presence of tumoral and humoral factors which are mainly responsible for the depletion of fat stores and muscular tissue. METHODS: In this work, we used cytotoxicity and enzymatic assays and morphological analysis to examine the effects of a proteolysis-inducing factor (PIF)-like molecule purified from ascitic fluid of Walker tumour-bearing rats (WF), which has been suggested to be responsible for muscle atrophy, on cultured C2C12 muscle cells. RESULTS: WF decreased the viability of C2C12 myotubes, especially at concentrations of 20-25 mug.mL-1. There was an increase in the content of the pro-oxidant malondialdehyde, and a decrease in antioxidant enzyme activity. Myotubes protein synthesis decreased and protein degradation increased together with an enhanced in the chymotrypsin-like enzyme activity, a measure of functional proteasome activity, after treatment with WF. Morphological alterations such as cell retraction and the presence of numerous cells in suspension were observed, particularly at high WF concentrations. CONCLUSION: These results indicate that WF has similar effects to those of proteolysis-inducing factor, but is less potent than the latter. Further studies are required to determine the precise role of WF in this experimental model. Β© 2008 Yano et al; licensee BioMed Central Ltd
Increased expression of phosphorylated forms of RNA-dependent protein kinase and eukaryotic initiation factor 2Ξ± may signal skeletal muscle atrophy in weight-losing cancer patients
Previous studies suggest that the activation (autophosphorylation) of dsRNA-dependent protein kinase (PKR) can stimulate protein degradation, and depress protein synthesis in skeletal muscle through phosphorylation of the translation initiation factor 2 (eIF2) on the Ξ±-subunit. To understand whether these mediators are important in muscle wasting in cancer patients, levels of the phospho forms of PKR and eIF2Ξ± have been determined in rectus abdominus muscle of weight losing patients with oesophago-gastric cancer, in comparison with healthy controls. Levels of both phospho PKR and phospho eIF2Ξ± were significantly enhanced in muscle of cancer patients with weight loss irrespective of the amount and there was a linear relationship between phosphorylation of PKR and phosphorylation of eIF2Ξ± (correlation coefficient 0.76, P=0.005). This suggests that phosphorylation of PKR led to phosphorylation of eIF2Ξ±. Myosin levels decreased as the weight loss increased, and there was a linear relationship between myosin expression and the extent of phosphorylation of eIF2Ξ± (correlation coefficient 0.77, P=0.004). These results suggest that phosphorylation of PKR may be an important initiator of muscle wasting in cancer patients
Association of food security status with overweight and dietary intake: exploration of White British and Pakistani-origin families in the Born in Bradford cohort.
BACKGROUND: Food insecurity has been associated with dietary intake and weight status in UK adults and children although results have been mixed and ethnicity has not been explored. We aimed to compare prevalence and trajectories of weight and dietary intakes among food secure and insecure White British and Pakistani-origin families. METHODS: At 12Β months postpartum, mothers in the Born in Bradford cohort completed a questionnaire on food security status and a food frequency questionnaire (FFQ) assessing their child's intake in the previous month; at 18Β months postpartum, mothers completed a short-form FFQ assessing dietary intake in the previous 12Β months. Weights and heights of mothers and infants were assessed at 12-, 24-, and 36-months postpartum, with an additional measurement of children taken at 4-5Β years. Associations between food security status and dietary intakes were assessed using Wilcoxon-Mann-Whitney for continuous variables and Ο2 or Fisher's exact tests for categorical variables. Quantile and logistic regression were used to determine dietary intakes adjusting for mother's age. Linear mixed effects models were used to assess longitudinal changes in body mass index (BMI) in mothers and BMI z-scores in children. RESULTS: At 12Β months postpartum, White British mothers reported more food insecurity than Pakistani-origin mothers (11% vs 7%; pβ<β0.01) and more food insecure mothers were overweight. Between 12 and 36Β months postpartum, BMI increased more among food insecure Pakistani-origin mothers (Ξ²β=β0.77Β units, [95% Confidence Interval [CI]: 0.40, 1.10]) than food secure (Ξ²β=β0.44Β units, 95% CI: 0.33, 0.55). This was also found in Pakistani-origin children (BMI z-score: food insecure Ξ²β=β0.40Β units, 95% CI: 0.22, 0.59; food secure Ξ²β=β0.25Β units, 95% CI: 0.20, 0.29). No significant increases in BMI were observed for food secure or insecure White British mothers while BMI z-score increased by 0.17 (95% CI: 0.13, 0.21) for food secure White British children. Food insecure mothers and children had dietary intakes of poorer quality, with fewer vegetables and higher consumption of sugar-sweetened drinks. CONCLUSIONS: Food security status is associated with body weight and dietary intakes differentially by ethnicity. These are important considerations for developing targeted interventions
Identification of Retinoic Acid in a High Content Screen for Agents that Overcome the Anti-Myogenic Effect of TGF-Beta-1
Transforming growth factor beta 1 (TGF-Ξ²1) is an inhibitor of muscle cell differentiation that is associated with fibrosis, poor regeneration and poor function in some diseases of muscle. When neutralizing antibodies to TGF-Ξ²1 or the angiotensin II inhibitor losartan were used to reduce TGF-Ξ²1 signaling, muscle morphology and function were restored in mouse models of Marfan Syndrome and muscular dystrophy. The goal of our studies was to identify additional agents that overcome the anti-myogenic effect of TGF-Ξ²1.A high-content cell-based assay was developed in a 96-well plate format that detects the expression of myosin heavy chain (MHC) in C2C12 cells. The assay was used to quantify the dose-dependent responses of C2C12 cell differentiation to TGF-Ξ²1 and to the TGF-Ξ²1 Type 1 receptor kinase inhibitor, SB431542. Thirteen agents previously described as promoting C2C12 differentiation in the absence of TGF-Ξ²1 were screened in the presence of TGF-Ξ²1. Only all-trans retinoic acid and 9-cis retinoic acid allowed a maximal level of C2C12 cell differentiation in the presence of TGF-Ξ²1; the angiotensin-converting enzyme inhibitor captopril and 10 nM estrogen provided partial rescue. Vitamin D was a potent inhibitor of retinoic acid-induced myogenesis in the presence of TGF-Ξ²1. TGF-Ξ²1 inhibits myoblast differentiation through activation of Smad3; however, retinoic acid did not inhibit TGF-Ξ²1-induced activation of a Smad3-dependent reporter gene in C2C12 cells.Retinoic acid alleviated the anti-myogenic effect of TGF-Ξ²1 by a Smad3-independent mechanism. With regard to the goal of improving muscle regeneration and function in individuals with muscle disease, the identification of retinoic acid is intriguing in that some retinoids are already approved for human therapy. However, retinoids also have well-described adverse effects. The quantitative, high-content assay will be useful to screen for less-toxic retinoids or combinations of agents that promote myoblast differentiation in the presence of TGF-Ξ²1
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