11 research outputs found

    Intra-Renal Hemodynamic Changes After Habitual Physical Activity in Patients with Chronic Kidney Disease

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    Background: Chronic Kidney Disease (CKD) is considered a silent epidemic with a continuously growing prevalence around the world. Due to uremia many functional and morphological abnormalities occur in almost all systems. Mostly affected, the cardiovascular system, leads to diminished cardiac function that affects patients’ functional capacity and physical activity levels, reducing survival and increasing all-cause mortality. Systematic exercise training ameliorates uremia induced body deficits and significantly improves the survival of CKD patients. Intradialytic exercise training has been recommended as a complementary therapeutic modality equally important to hemodialysis. Methods: The aim of this systematic review is to provide an update on recent advances in our understanding of how exercise training improves functionality of the cardiovascular system through the hemodynamic changes induced by habitual or intradialytic and/or home-based exercise training programs. Results: Systematic exercise training induces beneficial adaptive responses and influences many sensitive physiological biomarkers, such as oxidative stress biomarkers that are implicated in the development of atherosclerosis. Additionally, exercise training decreases the cardiovascular risk by improving the autonomic nervous system activity and the left ventricular function and by reducing nontraditional risk factors such as epicardial adipose tissue. It seems that all these central and peripheral adaptations to exercise training significantly contribute to improvements in functional capacity and exercise tolerance among CKD patients and result in the risk reduction of CKD-associated disorders. Conclusion: Exercise training could serve as a complimentary therapeutic strategy in CKD patients while health care providers should motivate patients to engage in any type of exercise training programs

    Systemic Redox Imbalance in Chronic Kidney Disease: A Systematic Review.

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    Patients with chronic kidney disease (CKD) experience imbalance between oxygen reactive species (ROS) production and antioxidant defenses leading to cell and tissue damage. However, it remains unclear at which stage of renal insufficiency the redox imbalance becomes more profound. The aim of this systematic review was to provide an update on recent advances in our understanding of how the redox status changes in the progression of renal disease from predialysis stages 1 to 4 to end stage 5 and whether the various treatments and dialysis modalities influence the redox balance. A systematic review was conducted searching PubMed and Scopus by using the Cochrane and PRISMA guidelines. In total, thirty-nine studies met the inclusion criteria and were reviewed. Even from an early stage, imbalance in redox status is evident and as the kidney function worsens it becomes more profound. Hemodialysis therapy per se seems to negatively influence the redox status by the elevation of lipid peroxidation markers, protein carbonylation, and impairing erythrocyte antioxidant defense. However, other dialysis modalities do not so far appear to confer advantages. Supplementation with antioxidants might assist and should be considered as an early intervention to halt premature atherogenesis development at an early stage of CKD

    Evidence of functional deficits at the single muscle fiber level in experimentally-induced renal insufficiency

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    Chronic kidney disease patients present with metabolic and functional muscle abnormalities, called uremic myopathy, whose mechanisms have not yet been fully elucidated. We investigated whether chronic renal insufficiency (CRI) affects skeletal muscle contractile properties at the cellular level. CRI was induced surgically in New Zealand rabbits (UREM), with sham-operation for controls (CON), and samples were collected at 3 months post-surgery, following euthanasia. All protocols had University Ethics approval following national and European guidelines. Sample treatments and evaluations were blinded. Maximal isometric force was assessed in 382 permeabilized psoas fibers (CON, n=142, UREM, n=240) initially at pH7, 10oC (‘standard’ conditions), in subsets of fibers in acidic conditions (pH6.2, 10oC) but also at near physiological temperature (pH7, 30oC and pH6.2, 30oC). CRI resulted in significant smaller average CSA (~11%) for UREM muscle fibers (vs CON, P<0.01). At standard conditions, UREM fibers produced lower absolute and specific forces (i.e. normalized force per fiber CSA) (vs CON, P<0.01); force increased in 30oC for both groups (P<0.01), but the disparity between UREM and CON remained significant. Acidosis significantly reduced force (vs pH7, 10oC P<0.01), similarly in both groups (in UREM by -48% and in CON by -43%, P>0.05). For the first time, we give evidence that CRI can induce significant impairments in single psoas muscle fibers force generation, only partially explained by fiber atrophy, thus affecting muscle mechanics at the cellular level

    Functional responses of uremic single skeletal muscle fibers to redox imbalances

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    The exact causes of skeletal muscle weakness in chronic kidney disease (CKD) remain unknown with uremic toxicity and redox imbalances being implicated. To understand whether uremic muscle has acquired any sensitivity to acute redox changes we examined the effects of redox disturbances on force generation capacity. Methods: Permeabilized single psoas fibers (N =37) from surgically induced CKD (UREM) and sham-operated (CON) rabbits were exposed to an oxidizing (10 mM Hydrogen Peroxide, H2O2) and/or a reducing [10 mM Dithiothreitol (DTT)] agent, in a blind design, in two sets of experiments examining: A) the acute effect of the addition of H2O2 on maximal (pCa 4.4) isometric force of actively contracting fibers and the effect of incubation in DTT on subsequent re-activation and force recovery (N =9 CON; N =9 UREM fibers); B) the effect of incubation in H2O2 on both submaximal (pCa 6.2) and maximal (pCa 4.4) calcium activated isometric force generation (N =9 CON; N =10 UREM fibers). Results: Based on cross-sectional area (CSA) calculations, a 14 % atrophy in UREM fibers was revealed; thus forces were evaluated in absolute values and corrected for CSA (specific force) values. A) Addition of H2O2 during activation did not significantly affect force generation in any group or the pool of fibers. Incubation in DTT did not affect the CON fibers but caused a 12 % maximal isometric force decrease in UREM fibers (both in absolute force p =0.024, and specific force, p =0.027). B) Incubation in H2O2 during relaxation lowered subsequent maximal (but not submaximal) isometric forces in the Pool of fibers by 3.5 % (for absolute force p =0.033, for specific force p =0.019) but not in the fiber groups separately. Conclusions: Force generation capacity of CON and UREM fibers is affected by oxidation similarly. However, DTT significantly lowered force in UREM muscle fibers. This may indicate that at baseline UREM muscle could have already been at a more reduced redox state than physiological. This observation warrants further investigation as it could be linked to disease-induced effects. HIPPOKRATIA 2017, 21(1): 3-7

    Nocturnal Activity Is Not Affected by a Long-Duration, Low-Intensity Single Exercise Bout

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    The aim of the current study was to examine whether prolonged low-intensity aerobic exercise could affect nocturnal activity in healthy individuals. Twenty-one healthy adults (24 &plusmn; 3.7 years; 9 females) were enrolled in this study. All participants participated in a 3-h low-intensity walking exercise protocol. Standard biochemical indices were assessed before the exercise protocol and at 72 h. Nocturnal activity and various indices of health were recorded for five consecutive days. The score of muscle pain peaked the night after the exercise protocol (p &lt; 0.05) and returned to baseline two days after. No statistical differences were found in any of the parameters examined, including nocturnal activity. Prolonged low-intensity exercise does not affect nocturnal activity. The anecdotal reports suggesting that exercise or/and physical activity could worsen symptoms of motor restlessness during sleep in sleep disorders, such as restless legs syndrome and periodic limb movements, are not supported by this study. However, these findings need to be verified in clinical populations, as well as by using protocols with different forms of exercise

    Long-term intradialytic hybrid exercise training on fatigue symptoms in patients receiving hemodialysis therapy

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    Purpose: Hemodialysis (HD) patients suffer from generalized weakness, exercise intolerance and muscle atrophy, all leading to generalized fatigue and lack of energy. HD patients spend at least 50% of their time in a functionally “switch off” mode with their fatigue sensations reaching a peak in the immediate hours after the dialysis session. The purpose of the current study was to assess the effectiveness of a nine-month hybrid intradialytic exercise program on fatigue symptoms occurring during and after hemodialysis session. Methods: Twenty stable hemodialysis patients were included in the study (59 ± 13.7 years; 16 males). All patients completed a 9-month supervised exercise training program composed of both aerobic cycling and resistance training during HD. Aspects related to physical and generalized fatigue were assessed via validated questionnaires, while physical performance was assessed by a battery of tests, before and after the intervention period. Results: Exercise capacity and physical performance were increased by an average of 65 and 40%, respectively. Patients reported feeling better during post-dialysis hours in question 1 (p = 0.000), question 3 (p = 0.009) and question 4 (p = 0.003) after the 9-month intervention. In addition, exercise training improved scores in cognitive function (p = 0.037), vitality (p = 0.05), depression (p = 0.000) and fatigue (p = 0.039). Conclusion: The present study showed that a 9-month hybrid (aerobic + resistance) exercise training program improved symptoms of post-dialysis fatigue and overall general perception of fatigue. Hybrid exercise training is a safe and effective non-pharmacological approach to ameliorate fatigue symptoms in HD patients

    Evidence of Blood and Muscle Redox Status Imbalance in Experimentally Induced Renal Insufficiency in a Rabbit Model

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    Chronic kidney disease (CKD) is accompanied by a disturbed redox homeostasis, especially in end-stage patients, which is associated with pathological complications such as anemia, atherosclerosis, and muscle atrophy. However, limited evidence exists about redox disturbances before the end stage of CKD. Moreover, the available redox literature has not yet provided clear associations between circulating and tissue-specific (muscle) oxidative stress levels. The aim of the study was to evaluate commonly used redox status indices in the blood and in two different types of skeletal muscle (psoas, soleus) in the predialysis stages of CKD, using an animal model of renal insufficiency, and to investigate whether blood redox status indices could be reflecting the skeletal muscle redox status. Indices evaluated included reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione reductase (GR), catalase (CAT), total antioxidant capacity (TAC), protein carbonyls (PC), and thiobarbituric acid reactive substances (TBARS). Results showed that blood GSH was higher in the uremic group compared to the control (17.50±1.73 vs. 12.43±1.01, p=0.033). In both muscle types, PC levels were higher in the uremic group compared to the control (psoas: 1.086±0.294 vs. 0.596±0.372, soleus: 2.52±0.29 vs. 0.929±0.41, p<0.05). The soleus had higher levels of TBARS, PC, GSH, CAT, and GR and lower TAC compared to the psoas in both groups. No significant correlations in redox status indices between the blood and skeletal muscles were found. However, in the uremic group, significant correlations between the psoas and soleus muscles in PC, GSSG, and CAT levels emerged, not present in the control. Even in the early stages of CKD, a disturbance in redox homeostasis was observed, which seemed to be muscle type-specific, while blood levels of redox indices did not seem to reflect the intramuscular condition. The above results highlight the need for further research in order to identify the key mechanisms driving the onset and progression of oxidative stress and its detrimental effects on CKD patients
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