Postexercise phosphocreatine recovery, an index of mitochondrial oxidative phosphorylation, is reduced in diabetic patients with lower extremity complications

Quantitative Assessment of Peripheral Oxidative Metabolism With a New Dynamic 1H MRI Technique: A Pilot Study in People With and Without Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is linked to impaired mitochondrial function. Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) is a gadolinium-contrast-free 1H method to assess mitochondrial function by measuring low-concentration metabolites. A CEST MRI-based technique may serve as a non-invasive proxy for assessing mitochondrial health.

HYPOTHESIS

A 1H CEST MRI technique may detect significant differences in in vivo skeletal muscle phosphocreatine (SMPCr) kinetics between healthy volunteers and T2DM patients undergoing standardized isometric exercise.

STUDY TYPE

Cross-sectional study.

SUBJECTS

Seven subjects without T2DM (T2DM-) and seven age, sex, and BMI-matched subjects with T2DM (T2DM+).

FIELD STRENGTH/SEQUENCE

Single-shot rapid acquisition with refocusing echoes (RARE) and single-shot gradient-echo sequences, 3 T.

ASSESSMENT

Subjects underwent a rest-exercise-recovery imaging protocol to dynamically acquire SMPCr maps in calf musculature. Medial gastrocnemius (MG) and soleus SMPCr concentrations were plotted over time, and SMPCr recovery time, τ , was determined. Mitochondrial function index was calculated as the ratio of resting SMPCr to τ . Participants underwent a second exercise protocol for imaging of skeletal muscle blood flow (SMBF), and its association with SMPCr was assessed.

STATISTICAL TESTS

Unpaired t-tests and Pearson correlation coefficient. A P value <0.05 was considered statistically significant.

RESULTS

SMPCr concentrations in MG and soleus displayed expected declines during exercise and returns to baseline during recovery. τ was significantly longer in the T2DM+ cohort (MG 83.5 ± 25.8 vs. 54.0 ± 21.1, soleus 90.5 ± 18.9 vs. 51.2 ± 14.5). The mitochondrial function index in the soleus was significantly lower in the T2DM+ cohort (0.33 ± 0.08 vs. 0.66 ± 0.19). SMBF was moderately correlated with the SMPCr in T2DM-; this correlation was not significant in T2DM+ (r = -0.23, P = 0.269).

CONCLUSION

The CEST MRI method is feasible for quantifying SMPCr in peripheral muscle tissue. T2DM+ individuals had significantly lower oxidative capacities than T2DM- individuals. In T2DM, skeletal muscle metabolism appeared to be decoupled from perfusion.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 1.

Unraveling the Role of Tumor Necrosis Factor-Alpha in Diabetic Peripheral Neuropathy: A Systematic Review and Meta-Analysis

Diabetic peripheral neuropathy (DPN) is a prevalent and debilitating complication of diabetes mellitus, leading to sensory abnormalities, decreased balance, and increased risk of foot problems. Although tumor necrosis factor-alpha (TNF-α) has emerged as a potential factor in the pathogenesis of DPN, its role remains contested. This study intends to thoroughly analyze the association between TNF-α and DPN by combining data from various global studies. This systematic review and meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and included 23 articles investigating TNF-α levels in DPN patients for systematic review and 11 articles for meta-analysis. Data were extracted, and heterogeneity was examined. A random-effect model was chosen due to high heterogeneity. The major outcome measure across studies was serum TNF-α levels. The meta-analysis found a significant mean difference of 15.2464 (95% confidence interval = 4.4963; 25.9965) under the random-effect model due to the substantial heterogeneity (I2 = 98.1%) among included studies. The meta-analysis indicates a consistent elevation in TNF-α levels in individuals with DPN compared to those without neuropathy. This underlines the potential of TNF-α as a biomarker and contributor to diabetic neuropathy. Despite heterogeneity, the study's extensive scope and systematic approach enhance the trustworthiness and generalizability of the findings.

Diabetic Peripheral Neuropathy Associated with Foot Ulcer: One of a Kind

Significance: Diabetic peripheral neuropathy (DPN) associated with a diabetic foot ulcer (DFU) is likely to be complicated with critical factors such as biofilm infection and compromised skin barrier function of the diabetic skin. Repaired skin with a history of biofilm infection is known to be compromised in barrier function. Loss of barrier function is also observed in the oxidative stress affected diabetic and aged skin. Recent Advances: Loss of barrier function makes the skin prone to biofilm infection and cellulitis, which contributes to chronic inflammation and vasculopathy. Hyperglycemia favors biofilm formation as glucose lowering led to reduction in biofilm development. While vasculopathy limits oxygen supply, the O2 cost of inflammation is high increasing hypoxia severity. Critical Issues: The host nervous system can be inhabited by bacteria. Because electrical impulses are a part of microbial physiology, polymicrobial colonization of the host's neural circuit is likely to influence transmission of action potential. The identification of perineural apatite in diabetic patients with peripheral neuropathy suggests bacterial involvement. DPN starts in both feet at the same time. Future Directions: Pair-matched studies of DPN in the foot affected with DFU (i.e., DFU-DPN) compared with DPN in the without ulcer, and intact skin barrier function, are likely to provide critical insight that would help inform effective care strategies. This review characterizes DFU-DPN from a translational science point of view presenting a new paradigm that recognizes the current literature in the context of factors that are unique to DFU-DPN.

Histopathological examination of the protective effect of intense exercise in apoptotic germ cell damage due to diabetes

PURPOSE

The aim of this study was to determine the protective and antioxidative effects of intensive exercise on streptozotocin (STZ)-induced testicular damage, apoptotic spermatognial cells death, and oxidative stress.

METHODS

36 male Sprague Dawley rats were divided into three groups: control, diabetes, and diabetes+intensive exercise (IE) groups. Testicular tissues were examined histopathologically and antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde (MDA) activity, as well as serum testosterone level, were measured.

RESULTS

Seminiferous tubules and germ cells were found to be better in the testis tissue of the intense exercise group than in the diabetes group. Diabetes suppressed antioxidant enzymes CAT, SOD, GPx and testosterone levels were significantly decreased, and increased MDA level in the diabetic group compared to diabetes+IE group (p < 0.001). Following four weeks of treatment, intensive exercise improved the antioxidant defense, significantly decreased MDA activity, and increased testosterone levels in testicular tissue in the diabetic group compared to diabetes+IE group (p < 0.01).

CONCLUSIONS

STZ-induced diabetes causes damage to the testis tissue. In order to prevent these damages, exercise practice has become very popular nowadays. In present study, our intensive exercise protocol, histological, and biochemical analysis of the effect of diabetes on the testicular tissues is shown.

Human studies of mitochondrial biology demonstrate an overall lack of binary sex differences: A multivariate meta-analysis

Mitochondria are maternally inherited organelles that play critical tissue-specific roles, including hormone synthesis and energy production, that influence human development, health, and aging. However, whether mitochondria from women and men exhibit consistent biological differences remains unclear, representing a major gap in knowledge. This meta-analysis systematically examined four domains and six subdomains of mitochondrial biology (total 39 measures), including mitochondrial content, respiratory capacity, reactive oxygen species (ROS) production, morphometry, and mitochondrial DNA copy number. Standardized effect sizes (Hedge's g) of sex differences were computed for each measure using data in 2258 participants (51.5% women) from 50 studies. Only two measures demonstrated aggregate binary sex differences: higher mitochondrial content in women's WAT and isolated leukocyte subpopulations (g = 0.20, χ² p = .01), and higher ROS production in men's skeletal muscle (g = 0.49, χ² p < .0001). Sex differences showed weak to no correlation with age or BMI. Studies with small sample sizes tended to overestimate effect sizes (r = -.17, p < .001), and sex differences varied by tissue examined. Our findings point to a wide variability of findings in the literature concerning possible binary sex differences in mitochondrial biology. Studies specifically designed to capture sex- and gender-related differences in mitochondrial biology are needed, including detailed considerations of physical activity and sex hormones.

Association between Osteoprotegerin and Charcot Neuroarthropathy: a systematic review

AIMS

Osteoprotegerin (OPG) has been associated with Charcot Neuroarthropathy (CN); however, three studied OPG polymorphisms (1181C > G, 245A > C and 950 T > C) have yielded conflicting results. Therefore, this meta-analysis was conducted to determine the difference in serum OPG concentrations between healthy controls and diabetics with and without CN and the effect OPG polymorphisms have on CN development.

METHODS

PubMed, LILAC, SCOPUS, and EBSCO databases and retrieved publications' bibliographies were searched for studies that examined for OPG and CN. Depending on the heterogeneity, fixed or random effects were used to calculate the pooled odds ratio (OR) or standard difference in means (SDM) with 95% confidence intervals (95%CI) for 5 genetic models (heterozygous, homozygous, dominant, recessive, and allelic) and serum concentrations, respectively.

RESULTS

Seven publications (12 studies) demonstrated that serum OPG concentrations were more elevated in subjects with CN (SDM = 0.719, 95%CI = 0.555-0.883, p < 0.001). When CN was compared to healthy controls or diabetics, the difference was more prominent for healthy controls (SDM = 1.043, 95%CI = 0.676-1.409, p < 0.001) than diabetics (SDM = 0.639, 95%CI = 0.456-0.821, p < 0.001) and the SDM difference was significant (p = 0.013). Using 6 publications (9 studies), neither the 1181C > G or the 950 T > C polymorphisms showed any significant associations for any genetic model. For the 245A > C polymorphism, only the homozygous genetic model showed a significant association between the polymorphism and CN (OR = 2.850, 95%CI: 1.051-7.729, p = 0.040).

CONCLUSIONS

Here, we determined a potential correlation between the CN and serum OPG concentrations and that only the CC genotype of the 245A > C polymorphism showed an increased risk of developing CN.

Electroacupuncture Alleviates Diabetic Peripheral Neuropathy by Regulating Glycolipid-Related GLO/AGEs/RAGE Axis

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes mellitus (DM) and affects over one-third of all patients. Neuropathic pain and nerve dysfunction induced by DM is related to the increase of advanced glycation end products (AGEs) produced by reactive dicarbonyl compounds in a hyperglycemia environment. AGEs induce the expression of pro-inflammatory cytokines via the main receptor (RAGE), which has been documented to play a crucial role in the pathogenesis of diabetic peripheral neuropathy. Electroacupuncture (EA) has been reported to have a positive effect on paralgesia caused by various diseases, but the mechanism is unclear. In this study, we used high-fat-fed low-dose streptozotocin-induced rats as a model of type 2 diabetes (T2DM). Persistent metabolic disorder led to mechanical and thermal hyperalgesia, as well as intraepidermal nerve fiber density reduction and nerve demyelination. EA improved neurological hyperalgesia, decreased the pro-inflammatory cytokines, reduced the generation of AGEs and RAGE, and regulated the glyoxalase system in the EA group. Taken together, our study suggested that EA plays a role in the treatment of T2DM-induced DPN, and is probably related to the regulation of metabolism and the secondary influence on the GLO/AGE/RAGE axis.

Skeletal Muscle Mitochondrial Dysfunction and Oxidative Stress in Peripheral Arterial Disease: A Unifying Mechanism and Therapeutic Target

Peripheral artery disease (PAD) is caused by atherosclerosis in the lower extremities, which leads to a spectrum of life-altering symptomatology, including claudication, ischemic rest pain, and gangrene requiring limb amputation. Current treatments for PAD are focused primarily on re-establishing blood flow to the ischemic tissue, implying that blood flow is the decisive factor that determines whether or not the tissue survives. Unfortunately, failure rates of endovascular and revascularization procedures remain unacceptably high and numerous cell- and gene-based vascular therapies have failed to demonstrate efficacy in clinical trials. The low success of vascular-focused therapies implies that non-vascular tissues, such as skeletal muscle and oxidative stress, may substantially contribute to PAD pathobiology. Clues toward the importance of skeletal muscle in PAD pathobiology stem from clinical observations that muscle function is a strong predictor of mortality. Mitochondrial impairments in muscle have been documented in PAD patients, although its potential role in clinical pathology is incompletely understood. In this review, we discuss the underlying mechanisms causing mitochondrial dysfunction in ischemic skeletal muscle, including causal evidence in rodent studies, and highlight emerging mitochondrial-targeted therapies that have potential to improve PAD outcomes. Particularly, we will analyze literature data on reactive oxygen species production and potential counteracting endogenous and exogenous antioxidants.

Topical L-thyroxine: The Cinderella among hormones waiting to dance on the floor of dermatological therapy?

Topical hormone therapy with natural or synthetic ligands of nuclear hormone receptors such as glucocorticoids, vitamin D analogues and retinoids has a long and highly successful tradition in dermatology. Yet the dermatological potential of thyroid hormone receptor (TR) agonists has been widely ignored, despite abundant clinical, cell and molecular biology, mouse in vivo, and human skin and hair follicle organ culture data documenting a role of TR-mediated signalling in skin physiology and pathology. Here, we review this evidence, with emphasis on wound healing and hair growth, and specifically highlight the therapeutic potential of repurposing topical L-thyroxine (T4) for selected applications in future dermatological therapy. We underscore the known systemic safety and efficacy profile of T4 in clinical medicine, and the well-documented impact of thyroid hormones on, for example, human epidermal and hair follicle physiology, hair follicle epithelial stem cells and pigmentation, keratin expression, mitochondrial energy metabolism and wound healing. On this background, we argue that short-term topical T4 treatment deserves careful further preclinical and clinical exploration for repurposing as a low-cost, effective and widely available dermatotherapeutic, namely in the management of skin ulcers and telogen effluvium, and that its predictable adverse effects are well-manageable.

The Role of Oxidative Stress in Peripheral Neuropathy

Peripheral neuropathy (PN) is a common disease affecting about 5% of the general population after the age of 50. Causes of PN are numerous and include genetic, diabetes, alcohol, vitamin deficiencies, and gluten sensitivity among others. This systematic review aimed to study the association between oxidative stress and PN in an attempt to better understand PN pathogenesis. A computer-based, systematic search was conducted on the PubMed database, and ensuing data from included articles was analyzed and discussed in this review. Sixty-nine papers were eligible and were used for this review. Peripheral neuropathy is associated with an increase of reactive oxygen species and a decrease in endogenous antioxidants. Genetic predisposition to oxidative damage may be a factor. Antioxidant treatment is promising regarding treatment. Though further research is necessary to better understand the underlying mechanism, it is evident that oxidative stress is implicated in the pathogenesis of - or is at least systematically present in - PN.

The Rise of Mitochondria in Peripheral Arterial Disease Physiopathology: Experimental and Clinical Data

Peripheral arterial disease (PAD) is a frequent and serious condition, potentially life-threatening and leading to lower-limb amputation. Its pathophysiology is generally related to ischemia-reperfusion cycles, secondary to reduction or interruption of the arterial blood flow followed by reperfusion episodes that are necessary but also—per se—deleterious. Skeletal muscles alterations significantly participate in PAD injuries, and interestingly, muscle mitochondrial dysfunctions have been demonstrated to be key events and to have a prognosis value. Decreased oxidative capacity due to mitochondrial respiratory chain impairment is associated with increased release of reactive oxygen species and reduction of calcium retention capacity leading thus to enhanced apoptosis. Therefore, targeting mitochondria might be a promising therapeutic approach in PAD.

Increased skeletal muscle mitochondrial free radical production in peripheral arterial disease despite preserved mitochondrial respiratory capacity

NEW FINDINGS

What is the central question of this study? What is the degree to which skeletal muscle mitochondria-derived reactive oxygen species (ROS) production is linked to impaired skeletal muscle function in patients with early-stage peripheral arterial disease (PAD) and what is the impact on mitochondrial respiratory capacity? What is the main finding and its importance? This is the first study to document increased mitochondria-derived reactive oxygen species production associated with elevated intramuscular oxidative stress, despite preserved mitochondrial respiratory function, in patients with PAD. Furthermore, systemic inflammation, mitochondria-derived ROS production and skeletal muscle oxidative stress were strongly correlated to disease severity, as indicated by ankle-brachial index, in patients with PAD.

ABSTRACT

Skeletal muscle mitochondrial dysfunction, which is not fully explained by disease-related arterial occlusion, has been implicated in the pathophysiology of peripheral arterial disease (PAD). Therefore, this study comprehensively assessed mitochondrial respiratory function in biopsies from the gastrocnemius of 10 patients with PAD (Fontaine Stage II) and 12 healthy controls (HC). Intramuscular and systemic inflammation, mitochondria-derived reactive oxygen species (ROS) production, and oxidative stress were also assessed to better understand the mechanisms responsible for the proposed PAD-induced mitochondrial dysfunction. Interestingly, mitochondrial respiratory capacity, assessed as complex I (CI) and complex II (CII)-driven State 3 respiration, measured separately and in combination (State 3 CI+II), revealed no difference between the patients with PAD and the HC. However, mitochondria-derived ROS production was significantly elevated in PAD (HC: 1.0 ± 0.9; PAD: 4.3 ± 1.0 AU (mg tissue)^-1 ). Furthermore, patients with PAD exhibited significantly greater concentrations of the pro-inflammatory markers tumour necrosis factor α in plasma (HC: 0.9 ± 0.4; PAD: 2.0 ± 0.3 pg ml^-1 ) and interleukin 6 in both plasma (HC: 2.3 ± 0.4; PAD: 4.3 ± 0.5 pg ml^-1 ) and muscle (∼75% greater). Intramuscular oxidative stress, assessed by protein carbonyls and 4-hydroxynonenal, was significantly greater in PAD compared to HC. Ankle brachial index was significantly correlated with intramuscular inflammation, oxidative stress and mitochondria-derived ROS production. Thus, elevated intramuscular inflammation, oxidative stress and mitochondria-derived ROS production are likely to contribute to the pathophysiology of the skeletal muscle dysfunction associated with PAD, even in the presence of preserved mitochondrial respiratory function in this population.

Declining Skeletal Muscle Function in Diabetic Peripheral Neuropathy

PURPOSE

The present review highlights current concepts regarding the effects of diabetic peripheral neuropathy (DPN) in skeletal muscle. It discusses the lack of effective pharmacologic treatments and the role of physical exercise intervention in limb protection and symptom reversal. It also highlights the importance of magnetic resonance imaging (MRI) techniques in providing a mechanistic understanding of the disease and helping develop targeted treatments.

METHODS

This review provides a comprehensive reporting on the effects of DPN in the skeletal muscle of patients with diabetes. It also provides an update on the most recent trials of exercise intervention targeting DPN pathology. Lastly, we report on emerging MRI techniques that have shown promise in providing a mechanistic understanding of DPN and can help improve the design and implementation of clinical trials in the future.

FINDINGS

Impairments in lower limb muscles reduce functional capacity and contribute to altered gait, increased fall risk, and impaired balance in patients with DPN. This finding is an important concern for patients with DPN because their falls are likely to be injurious and lead to bone fractures, poorly healing wounds, and chronic infections that may require amputation. Preliminary studies have shown that moderate-intensity exercise programs are well tolerated by patients with DPN. They can improve their cardiorespiratory function and partially reverse some of the symptoms of DPN. MRI has the potential to bring new mechanistic insights into the effects of DPN as well as to objectively measure small changes in DPN pathology as a result of intervention.

IMPLICATIONS

Noninvasive exercise intervention is particularly valuable in DPN because of its safety, low cost, and potential to augment pharmacologic interventions. As we gain a better mechanistic understanding of the disease, more targeted and effective interventions can be designed.

Effect of Linagliptin on Vascular Function: A Randomized, Placebo-controlled Study

CONTEXT

The dipeptidyl peptidase-4 inhibitor, linagliptin, possesses pleiotropic vasodilatory, antioxidant, and anti-inflammatory properties in animals, independent of its glucose-lowering properties. Although large, randomized clinical trials are being conducted to better evaluate the efficacy and safety of linagliptin on cardiovascular outcomes, little is known about its effects on vascular function in humans.

OBJECTIVE

This study sought to evaluate the effect of linagliptin on surrogates of vascular and mitochondrial function.

DESIGN AND SETTING

This was a randomized, double-blind, placebo-controlled trial at a tertiary care center with a large type 2 diabetes referral base.

PATIENTS AND INTERVENTION

Forty participants with type 2 diabetes were included in a 12-wk treatment of either linagliptin 5mg/d or placebo.

MAIN OUTCOME MEASURES

Micro- and macrovascular functions were assessed using laser Doppler coupled with iontophoresis and with brachial flow-mediated dilation, respectively. Mitochondrial function was assessed by phosphorus-31 metabolites changes in the calf muscle measured by magnetic resonance spectroscopy. Circulating endothelial progenitor cells, as well as inflammatory cytokines, growth factors, and biomarkers of endothelial function were also quantified.

RESULTS

Linagliptin was associated with an increase in axon reflex-dependent vasodilation, a marker of neurovascular function (P = .05). A trend indicating increased endothelium-dependent microvascular reactivity was observed (P = .07). These were associated with decreases in concentrations of IFNγ (P < .05), IL-6 (P = .03), IL-12 (P < .03), and MIP-1 (P < .04) following linagliptin treatment when compared with placebo.

CONCLUSIONS

This study demonstrates that linagliptin tends to improve endothelial and neurovascular microvascular function and is associated with decreased markers of inflammation in patients with type 2 diabetes. There was no significant effect of linagliptin on mitochondrial function, macrovascular function, or endothelial progenitor cells.

Revascularization and muscle adaptation to limb demand ischemia in diet-induced obese mice

BACKGROUND

Obesity and type 2 diabetes are major risk factors for peripheral arterial disease in humans, which can result in lower limb demand ischemia and exercise intolerance. Exercise triggers skeletal muscle adaptation including increased vasculogenesis. The goal of this study was to determine whether demand ischemia modulates revascularization, fiber size, and signaling pathways in the ischemic hind limb muscles of mice with diet-induced obesity (DIO).

MATERIALS AND METHODS

DIO mice (n = 7) underwent unilateral femoral artery ligation and recovered for 2 wks followed by 4 wks with daily treadmill exercise to induce demand ischemia. A parallel sedentary ischemia (SI) group (n = 7) had femoral artery ligation without exercise. The contralateral limb muscles of SI served as control. Muscles were examined for capillary density, myofiber cross-sectional area, cytokine levels, and phosphorylation of STAT3 and ERK1/2.

RESULTS

Exercise significantly enhanced capillary density (P < 0.01) and markedly lowered cross-sectional area (P < 0.001) in demand ischemia compared with SI. These findings coincided with a significant increase in granulocyte colony-stimulating factor (P < 0.001) and interleukin-7 (P < 0.01) levels. In addition, phosphorylation levels of STAT3 and ERK1/2 (P < 0.01) were increased, whereas UCP1 and monocyte chemoattractant protein-1 protein levels were lower (P < 0.05) without altering vascular endothelial growth factor and tumor necrosis factor alpha protein levels. Demand ischemia increased the PGC1α messenger RNA (P < 0.001) without augmenting PGC1α protein levels.

CONCLUSIONS

Exercise-induced limb demand ischemia in the setting of DIO causes myofiber atrophy despite an increase in muscle capillary density. The combination of persistent increase in tumor necrosis factor alpha, lower vascular endothelial growth factor, and failure to increase PGC1α protein may reflect a deficient adaption to demand ischemia in DIO.

PGC-1α and PGC-1β increase CrT expression and creatine uptake in myotubes via ERRα

Intramuscular creatine plays a crucial role in maintaining skeletal muscle energy homeostasis, and its entry into the cell is dependent upon the sodium chloride dependent Creatine Transporter (CrT; Slc6a8). CrT activity is regulated by a number of factors including extra- and intracellular creatine concentrations, hormones, changes in sodium concentration, and kinase activity, however very little is known about the regulation of CrT gene expression. The present study aimed to investigate how Creatine Transporter (CrT) gene expression is regulated in skeletal muscle. Within the first intron of the CrT gene, we identified a conserved sequence that includes the motif recognized by the Estrogen-related receptor α (ERRα), also known as an Estrogen-related receptor response element (ERRE). Additional ERREs confirming to the known consensus sequence were also identified in the region upstream of the promoter. When partnered with peroxisome proliferator-activated receptor-gamma co-activator-1alpha (PGC-1α) or beta (PGC-1β), ERRα induces the expression of many genes important for cellular bioenergetics. We therefore hypothesized that PGC-1 and ERRα could also regulate CrT gene expression and creatine uptake in skeletal muscle. Here we show that adenoviral overexpression of PGC-1α or PGC-1β in L6 myotubes increased CrT mRNA (2.1 and 1.7-fold, P<0.0125) and creatine uptake (1.8 and 1.6-fold, P<0.0125), and this effect was inhibited with co-expression of shRNA for ERRα. Overexpression of a constitutively active ERRα (VP16-ERRα) increased CrT mRNA approximately 8-fold (P<0.05), resulting in a 2.2-fold (P<0.05) increase in creatine uptake. Lastly, chromatin immunoprecipitation assays revealed that PGC-1α and ERRα directly interact with the CrT gene and increase CrT gene expression.

Role of exercise in the management of diabetes mellitus: the global scenario

Background

Exercise training programs have emerged as a useful therapeutic regimen for the management of type 2 diabetes mellitus (T2DM). Majority of the Western studies highlighted the effective role of exercise in T2DM. Therefore, the main aim was to focus on the extent, type of exercise and its clinical significance in T2DM in order to educate the clinicians from developing countries, especially in Asians.

Methods

Pubmed, Science Direct, Scopus, ISI Web of Knowledge and Google scholar were searched using the terms “type 2 diabetes mellitus,” “type 2 DM,” “exercise,” and/or “physical activity,” and “type 2 diabetes mellitus with exercise.” Only clinical or human studies published in English language between 2000 and 2012 were included. Certain criteria were assigned to achieve appropriate results.

Results

Twenty five studies met the selected criteria. The majority of the studies were randomized controlled trial study design (65%). Most of the aerobic exercise based studies showed a beneficial effect in T2DM. Resistance exercise also proved to have positive effect on T2DM patients. Minimal studies related to other types of exercises such as yoga classes, joba riding and endurance-type exercise were found. On the other hand, United States of America (USA) showed strong interest of exercise management towards T2DM.

Conclusion

Aerobic exercise is more common in clinical practice compared to resistance exercise in managing T2DM. Treatment of T2DM with exercise training showed promising role in USA. A large number of researches are mandatory in the developing countries for incorporating exercise in the effective management of T2DM.

Mitochondrial dysfunction in neuromuscular disorders

This review deciphers aspects of mitochondrial (mt) dysfunction among nosologically, pathologically, and genetically diverse diseases of the skeletal muscle, lower motor neuron, and peripheral nerve, which fall outside the traditional realm of mt cytopathies. Special emphasis is given to well-characterized mt abnormalities in collagen VI myopathies (Ullrich congenital muscular dystrophy and Bethlem myopathy), megaconial congenital muscular dystrophy, limb-girdle muscular dystrophy type 2 (calpainopathy), centronuclear myopathies, core myopathies, inflammatory myopathies, spinal muscular atrophy, Charcot-Marie-Tooth neuropathy type 2, and drug-induced peripheral neuropathies. Among inflammatory myopathies, mt abnormalities are more prominent in inclusion body myositis and a subset of polymyositis with mt pathology, both of which are refractory to corticosteroid treatment. Awareness is raised about instances of phenotypic mimicry between cases harboring primary mtDNA depletion, in the context of mtDNA depletion syndrome, and established neuromuscular disorders such as spinal muscular atrophy. A substantial body of experimental work, derived from animal models, attests to a major role of mitochondria (mt) in the early process of muscle degeneration. Common mechanisms of mt-related cell injury include dysregulation of the mt permeability transition pore opening and defective autophagy. The therapeutic use of mt permeability transition pore modifiers holds promise in various neuromuscular disorders, including muscular dystrophies.

Inflammation: therapeutic targets for diabetic neuropathy

There are still no approved treatments for the prevention or of cure of diabetic neuropathy, and only symptomatic pain therapies of variable efficacy are available. Inflammation is a cardinal pathogenic mechanism of diabetic neuropathy. The relationships between inflammation and the development of diabetic neuropathy involve complex molecular networks and processes. Herein, we review the key inflammatory molecules (inflammatory cytokines, adhesion molecules, chemokines) and pathways (nuclear factor kappa B, JUN N-terminal kinase) implicated in the development and progression of diabetic neuropathy. Advances in the understanding of the roles of these key inflammatory molecules and pathways in diabetic neuropathy will facilitate the discovery of the potential of anti-inflammatory approaches for the inhibition of the development of neuropathy. Specifically, many anti-inflammatory drugs significantly inhibit the development of different aspects of diabetic neuropathy in animal models and clinical trials.