Chronic kidney disease (CKD) patients are at risk for protein-energy wasting, abnormal body composition and impaired physical capacity. These complications lead to increased risk of hospitalization, morbidity and mortality.In CKD patient as well as in healthy people, there is a close association between nutrition and physical activity. Namely, inadequate nutrient (energy) intake impairs physical performance thus favoring a sedentary lifestyle: this further contributes to loss of muscle strength and mass, which limit the quality of life and rehabilitation of CKD patients. In CKD as well as in end-stage-renal-disease patients, regular physical activity coupled with adequate energy and protein intake counteracts protein-energy wasting and related comorbidity and mortality. In summary, exercise training can positively influence nutritional status and the perception of well-being of CKD patients and may facilitate the anabolic effects of nutritional interventions.

Background Trimethylamine N-oxide (TMAO), a metabolite from red meat and fish consumption, plays a role in promoting cardiovascular events. However, data regarding TMAO and its impact on clinical outcomes are inconclusive, possibly due to its undetermined dietary source. Objective We hypothesized circulating TMAO derived from fish intake might cause less harm compared to red meat source by examining the concomitant level of 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), a known biomarker of fish intake, and investigated the association between TMAO, CMPF and outcomes. Design Patients were recruited from the European QUALity study on treatment in advanced CKD (EQUAL) among individuals ≥65 years whose eGFR had dropped for the first time to ≤20mL/min/1.73m2 during last 6 months. The association between TMAO, CMPF and outcomes including all-cause mortality and kidney replacement therapy (KRT) was assessed among 737 patients. Patients were further stratified by median cut-offs of TMAO and CMPF, suggesting high/low red meat and fish intake. Results During a median of 39 months’ follow-up, 232 patients died. Higher TMAO was independently associated with an increased risk of all-cause mortality (multivariable-hazard ratio (HR) 1.46, 95% confidence interval (CI) 1.17, 1.83). Higher CMPF was associated with a reduced risk of both all-cause mortality (HR 0.79, 95%CI 0.71, 0.89) and KRT (HR 0.80, 95%CI 0.71, 0.90), independent of TMAO and other clinically relevant confounders. In comparison to patients with low TMAO and CMPF, patients with low TMAO and high CMPF had reduced risk of all-cause mortality (adjusted HR 0.49, 95% CI 0.31, 0.73), whereas those with high TMAO and high CMPF showed no association across adjusted models. Conclusions High CMPF conferred an independent role in health benefits and might even counteract the unfavorable association between TMAO and outcomes. Whether higher circulating CMPF are due to fish consumption, and/or CMPF is a protective factor remains to be verified.

It is, nowadays, possible to simulate biological processes in conditions that mimic the different cellular compartments. Several groups have performed these calculations using molecular models that vary in performance and accuracy. In many cases, the atomistic degrees of freedom have been eliminated, sacrificing both structural complexity and chemical specificity to be able to explore slow processes. In this review, we will discuss the insights gained from computer simulations on macromolecule diffusion, nuclear body formation, and processes involving the genetic material inside cell-mimicking spaces. We will also discuss the challenges to generate new models suitable for the simulations of biological processes on a cell scale and for cellcycle-long times, including non-equilibrium events such as the co-translational folding, misfolding, and aggregation of proteins. A prominent role will be played by the wise choice of the structural simplifications and, simultaneously, of a relatively complex energetic description. These challenging tasks will rely on the integration of experimental and computational methods, achieved through the application of efficient algorithms.

Sedentary lifestyle is frequent in hemodialysis patients whose physical capabilities are largely reduced when compared with healthy subjects, and evidence exists that sedentary dialysis patients are at higher risk of death as compared to non-sedentary ones. Dialysis patients may suffer from cardiovascular disease, diabetes, malnutrition, depression, which limits their exercise capacity; conversely, regular physical exercise may favor rehabilitation and correction of several cardiovascular, metabolic and nutritional abnormalities. Many observational, population-based studies show that the level of physical activity is related to quality of life and nutritional status, as well as to the survival probability. Intervention studies are instead lacking; a randomized controlled multicenter trial is in progress in Italy to assess the effect of home-based exercise programs on survival and hospitalization rate in stable dialysis patients. Implementation of physical activity should be one of the goals of dialysis care management, but several barriers prevent a widespread implementation of physical exercise programs in the dialysis units. A lack of patients' or care-givers' motivation or willingness, and structural or functional resources are the most frequent obstacles to exercise implementation. Since the hemodialysis population is quite heterogeneous for physical abilities and comorbidities, exercise in not for everyone and individual prescription is required for a correct and safe implementation of physical activity.

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Background Patients with stage 4/5 chronic kidney disease (CKD) suffer from various symptoms. The retention of uremic solutes is thought to be associated with those symptoms. However, there are relatively few rigorous studies on the potential links between uremic toxins and symptoms in patients with CKD. Methods The EQUAL study is an ongoing observational cohort study of non-dialyzed patients with stage 4/5 CKD. EQUAL patients from Germany, Poland, Sweden, and the United Kingdom were included in the present study (n = 795). Data and symptoms self-report questionnaires were collected between April 2012 and September 2020. Baseline uric acid and parathyroid hormone and ten uremic toxins were quantified. We tested the association between uremic toxins and symptoms, and adjusted p-values for multiple testing. Results Symptoms were more frequent in women than in men with stage 4/5 CKD, while levels of various uremic toxins were higher in men. Only trimethylamine-N-oxide (positive association with fatigue), p-cresylsulfate with constipation, and 3 carboxy-4-methyl-5-propyl-2-furanpropionic acid (negative association with shortness of breath) demonstrated moderately strong associations with symptoms in adjusted analysis. The association of phenylacetylglutamine with shortness of breath was consistent in both sexes, although only reached statistical significance in the full population. By contrast, trimethylamine-N-oxide (fatigue) and p-cresyl sulfate and phenylacetylglutamine (constipation) were only associated with symptoms in men, who presented higher serum levels than women. Conclusion Only a limited number of toxins were associated with symptoms in persons with stage 4/5 CKD. Other uremic toxins, uremia related factors or psychosocial factors not yet explored might contribute to symptom burden.

Background: Optimizing vascular access outcomes is still a challenge, since 30-60% of arteriovenous fistulas fail or do not mature and catheters are widely used in contemporary patients. Methods: This study reports on strategies and outcomes in a single center in which access planning, surgery and maintenance are managed by a team of nephrologists. We retrospectively analyzed 305 fistulas and 61 grafts created in 270 consecutive patients between 2002 and 2013. Results: The percentage of patients receiving a fistula or graft who initiated hemodialysis with a mature access was 68.6%. Among prevalent patients, 71.7% used a fistula, 15.7% a graft and 12.6% a catheter. Rates of primary failure and revision before cannulation were 14.4 and 1.6% for fistulas vs. 4.9 and 3.3% for grafts. After maturation, complications (1.040 vs. 0.188 per patient-year (py)) and interventions (0.743 vs. 0.066 per py) were greater for grafts than for fistulas (p < 0.001). Secondary patency did not significantly differ between grafts and fistulas (median survival 34.8 vs. 57.3 months, p = 0.36), unless primary failures were excluded from Kaplan-Meier analysis (median survival 34.9 vs. 70.9 months, p = 0.03). Conclusions: High fistula prevalence, low access-related morbidity and catheter dependence were achieved using individualized strategies, including mid-forearm or perforating vein fistula creation and selective graft placement in high risk patients. Direct involvement of nephrologists throughout all steps of access care can improve access outcomes, by promoting a patient-centered approach.

LessonThis case offers a starting point for a literature review on peritoneal ultrafiltration in refractory heart failure.