Antonio Fernández-Perpén

Epithelial-to-mesenchymal transition of mesothelial cells is an early event during peritoneal dialysis and is associated with high peritoneal transport.

Ultrafiltration (UF) failure is a consequence of long-term peritoneal dialysis (PD). Fibrosis, angiogenesis, and vasculopathy are causes of this functional disorder after 3-8 years on PD. Epithelial-to-mesenchymal transition (EMT) of mesothelial cell (MC) is a key process leading to peritoneal fibrosis with functional deterioration. Our purpose was to study the peritoneal anatomical changes during the first months on PD, and to correlate them with peritoneal functional parameters. We studied 35 stable PD patients for up to 2 years on PD, with a mean age of 45.3+/-14.5 years. Seventy-four percent of patients presented loss of the mesothelial layer, 46% fibrosis (>150 microm) and 17% in situ evidence of EMT (submesothelial cytokeratin staining), which increased over time. All patients with EMT showed myofibroblasts, while only 36% of patients without EMT had myofibroblasts. The number of peritoneal vessels did not vary when we compared different times on PD. Vasculopathy was present in 17% of the samples. Functional studies were used to define the peritoneal transport status. Patients in the highest quartile of mass transfer area coefficient of creatinine (Cr-MTAC) (>11.8 ml min(-1)) showed significantly higher EMT prevalence (P=0.016) but similar number of peritoneal vessels. In the multivariate analysis, the highest quartile of Cr-MTAC remained as an independent factor predicting the presence of EMT (odds ratio 12.4; confidence interval: 1.6-92; P=0.013) after adjusting for fibrosis (P=0.018). We concluded that, during the first 2 PD years, EMT of MCs is a frequent morphological change in the peritoneal membrane. High solute transport status is associated with its presence but not with increased number of peritoneal vessels.

Eating behavior disorders in uremia: a question of balance in appetite regulation.

Eating and appetite disorders are frequent complications of the uremic syndrome which contribute to malnutrition in dialysis patients. The data suggest that uremic anorexia may occur with or without abdominal and visceral fat accumulation despite a lower food intake. This form of obesity (i.e., with low food intake and malnutrition) is more common in dialysis patients than obesity with high food intake. This article reviews the current knowledge regarding mechanisms responsible for appetite regulation in normal conditions and in uremic patients. Anorexia in dialysis patients has been historically considered as a sign of uremic toxicity due to ‘‘inadequate’’ dialysis as judged by uncertain means (‘‘middle molecule’’ accumulation, Kt/V, ‘‘peak‐concentration hypothesis,’’ and others). We propose the tryptophan‐serotonin hypothesis, based on a uremia‐induced disorder in patients’ amino acid profile—low concentrations of large neutral and branched‐chain amino acids with high tryptophan levels. A high rate of tryptophan transport across the blood‐brain barrier increases the synthesis of serotonin, a major appetite inhibitor. Inflammation may also play a role in the genesis of anorexia and malnutrition. For example, silent infection with Helicobacter pylori may be a source of cytokines with cachectic action; its eradication improves appetite and nutrition. The evaluation of appetite should take into account cultural and social aspects. Uremic patients showed a universal trend to carbohydrate preference and red meat refusal compared to healthy people. In contrast, white meat was less problematic. Uremic patients also have a remarkable attraction for citrics and strong flavors in general. Eating preferences or refusals have been related to the predominance of some appetite peptide modulators. High levels of cholecystokinin (CCK) (a powerful anorexigen) are associated with early satiety for carbohydrates and neuropeptide Y (NPY) (an orexigen) with repeated food intake. Obesity and elevated body mass index often falsely suggest a good nutritional status. In uremic patients (a hyperinsulinemia state), disorders in the regulation of fat distribution (insulin, leptin, insulin‐like growth factor [IGF]‐1, fatty acids, and disorders in receptors for insulin, lipoprotein lipase, mitochondrial uncoupling protein‐2, and β3‐adrenoreceptors) may cause abdominal fat accumulation without an increase in appetite. Finally, appetite regulation in uremia is highly complex. Disorders in adipose tissue, gastrointestinal and neuropeptides, retained or hyperproduced inflammatory end products, and central nervous system changes may all play a role. Uremic anorexia may be explained by a hypothalamic hyperserotoninergic state derived from a high concentration of tryptophan and low branched‐chain amino acids.

Comparisons of hemodialysis and CAPD in patients over 65 years of age: a meta-analysis.

This meta-analysis had the aim of studyingthe available studies on comparison betweenHemodialysis and Peritoneal Dialysis in theelderly. The final objective was to reach, ifpossible, evidence for potential differences.In the case that no differences could bedemonstrated, contribute to accept that HD andPD are similar techniques to be offered toelderly people requiring dialysis.The question formulated was this: Do we haveadequately contrasted data on results forsurvival, hospitalization rate, quality of lifeand morbidity on hemodialysis and peritonealdialysis in the elderly (more than 65 yearsold)?As data sources we selected eight papers thatcompared the general results of these twodialysis techniques. Different elements wereconsidered in this selection because nonereached the two first levels in the hierarchyof sources of evidence, and only two reachedthe third level – that of prospective studies;this is because an oral presentation of datahas been included in a meta-analysis. Anotherfour papers – uni- or multicenter retrospectivestudies compared the results obtained with PDand HD. The remaining two papers – reports fromnationwide registries that compare of mortalityrates, adjusted for co-morbid conditions andage, present specific results on groups ofelderly patients. Three papers compareparticular aspects of the two techniques,including nutritional status, psychiatric andpsychosocial aspects and rehabilitation, inthis case comparing PD with home hemodialysispatients. Finally, we have included theopinions of healthy elderly people on dialysisissues.This meta-analysis of these different studiessuggests that the mortality and hospitalizationrate of elderly people treated by PD is similarto that of similar people treated by HD. Inconsequence, we have no reasons to selecteither therapy on behalf of the patient. Thenephrologist should consider and inform thepatient and family about the relativeadvantages and disadvantages of both techniquesand tailor dialysis technique choice to thespecific individual to assure the best results.Local circumstances should also be considered.protection.

Biocompatible dialysis solutions preserve peritoneal mesothelial cell and vessel wall integrity. A case-control study on human biopsies

♦ Introduction: Chronic exposure to conventional peritoneal dialysis (PD) solutions has been related to peritoneal function alterations in PD patients, and associated with mesothelial cell loss, submesothelial fibrosis, vasculopathy, and angiogenesis. In vitro and ex vivo analyses, as well as studies with animal models, have demonstrated that biocompatible PD solutions attenuate these morphological alterations. Our aim was to confirm the morphological benefits of biocompatible solutions in PD patients. ♦ Methods: We analyzed biopsies from 23 patients treated with biocompatible solutions (study group, SG), and compared them with a control group (n = 23) treated with conventional solutions (CG), matched for time on PD. ♦ Results: A total of 56.5% of SG patients showed total or partial preservation of mesothelial cells monolayer, in contrast with 26.1% of patients in CG (p = 0.036). Peritoneal fibrosis was not significantly less frequent in SG patients (47.8% SG vs 69.6% CG; p = 0.13). In patients without previous peritonitis, a significantly lower prevalence of fibrosis was present in SG patients (41.7% SG vs 77.8% CG; p = 0.04). Hyalinizing vasculopathy (HV) was significantly lower in SG (4.3% SG vs 30.4% CG; p = 0.02). Cytokeratin-positive fibroblast-like cells were detected in 10 patients (22%), but the prevalence was not significantly lower in SG. In the univariate regression analysis, the use of biocompatible solutions was associated with mesothelial monolayer integrity (p = 0.04) and an absence of vasculopathy (p = 0.04). ♦ Conclusion: The present study demonstrates in vivo in human biopsies that biocompatible solutions are better tolerated by the peritoneum in the medium and long term than conventional solutions.

Cumplimiento de objetivos de calidad y evolución de los pacientes incidentes en diálisis peritoneal

INTRODUCTION In 2007 the Scientific Quality-technical and Improvement of Quality in Peritoneal Dialysis was edited. It includes several quality indicators. As far as we know, only some groups of work had evaluated these indicators, with inconclusive results. AIM To study the evolution and impact of guidelines in Peritoneal Dialysis. METHODS Prospective cohort study of each incident of patients in Peritoneal Dialysis, in a regional public health care system (2003-2006). We prospectively collected baseline clinical and analytical data, technical efficacy, cardiovascular risk, events and deaths, hospital admissions and also prescription data was collected every 6 months. RESULTS Over a period of 3 years, 490 patients (53.58 years of age; 61.6% males.) Causes of ERC: glomerular 25.5%, diabetes 16%, vascular 12.4%, and interstitial 13.3%. 26.48% were on the list for transplant. Dialysis efficacy: Of the first available results, the residual renal function was 6.37 ml/min, achieving 67.6% of all the objectives K/DOQI. 38.6% remained within the range during the entire first year. Anaemia: 79.3% received erythropoietic stimulating agents and maintained an average Hb of 12.1 g/dl. The percentage of patients in the range (Hb: 11-13 g/dl) improved after a year (58.4% vs 56.3% keeping in the range during this time of 25.6%). Evolution: it has been estimated that per patient-year the risk of: 1) mortality is 0.06 IC 95% [0.04-0.08]; 2) admissions 0.65 [0.58-0.72]; 3) peritoneal infections 0.5 [0.44-0.56]. CONCLUSION Diabetes Mellitus patients had a higher cardiovascular risk and prevalence of events. The degrees of control during the follow-up in many topics of peritoneal dialysis improve each year; however they are far from the recommended guidelines, especially if they are evaluated throughout the whole study.