Risk factors associated with the deterioration of renal function after kidney transplantation

Risk factors associated with the deterioration of renal function after kidney transplantation Renal function early after transplantation is associated with a large number of risk factors, including donor age and acute rejection. During the 1990s, donor age increased and the incidence of acute rejection decreased. Renal function between the third and sixth month improved slightly, while renal function deterioration between the third or sixth month and the 12th month improved significantly. This modification coincides with the introduction of mycophenolate mofetil and tacrolimus. The tendency for sustained renal improvement early after transplantation became more evident after the introduction of anti-calcineurin–free regimens. Studies of protocol biopsies have shown that there is an increase of glomerular volume after transplantation and that a larger glomerular volume at 4 months is associated with a better glomerular filtration rate. This adaptation mechanism is impaired in patients with chronic allograft nephropathy or in patients with high cyclosporin levels. Taken together, these data suggest that the steady improvement of renal allograft function may be partly explained by a better glomerular adaptation after transplantation because of the avoidance of the vasoconstrictive effect of anti-calcineurinic agents, and a significant decrease in the prevalence of chronic allograft nephropathy early after transplantation

Multiple, large separation site diversity

[ANGLÈS] Nowadays, it is usual that Earth-Space communications make use of high frequency bands like the Ka-band and above due to the fact that lower bands are saturated and higher capacities are needed. However, at these frequencies the Earth-Space path is strongly affected by atmospheric phenomena, especially by rain attenuation, limiting the Earth-Satellite link availability. One of the best fade mitigation techniques against rain is site diversity which takes advantage of the spatial structure of rain to counteract it. In this work, three different scenarios are studied through simulations with time-series of rain attenuation at 20 GHz in order to evaluate the effectiveness in terms of propagation of multiple-site diversity from a small-scale to large-scale. Results show that technical requirements in terms of transmit power or antenna gain of ground stations can be relaxed in order to maintain a reliable communication more than 99.99% of the time thanks to the significant improvement in terms of diversity advantage or achieve higher availability for the equipment use.[CASTELLÀ] Hoy en día es habitual que las comunicaciones Tierra-Espacio hagan uso de bandas de frecuencia elevadas tales como la banda Ka y superiores debido a que las bandas inferiores están saturadas y se necesitan mayores capacidades. Sin embargo, a estas frecuencias el camino Tierra-Espacio se ve fuertemente afectado por fenómenos atmosféricos, especialmente por la atenuación de la lluvia, limitando la disponibilidad del enlace Tierra-Satélite. Una de las mejores técnicas de mitigación de desvanecimientos contra la lluvia es la diversidad de lugar la cual aprovecha la estructura espacial de la lluvia para contrarrestar sus efectos. En este trabajo, tres escenarios diferentes son estudiados a través de simulaciones con time-series de atenuación de lluvia a 20 GHz para evaluar la eficacia de la diversidad de lugar múltiple en términos de propagación desde una pequeña escala hasta una gran escala. Los resultados muestran que los requerimientos técnicos en términos de potencia transmitida o ganancia de antena de las estaciones terrestres se pueden relajar para mantener una comunicación fiable más del 99.99 % del tiempo gracias a la significativa mejora introducida por la diversidad o alcanzar mayor disponibilidad con el uso del equipo.[CATALÀ] Avui en dia, és habitual que les comunicacions Terra-Espai facin ús de bandes freqüencials elevades tals com la banda Ka i superiors atès que les bandes inferiors estan saturades i es requereixen majors capacitats. No obstant, a aquestes freqüències, el camí Terra-Espai es veu greument afectat per fenòmens atmosfèrics, especialment per l'atenuació de la pluja, limitant la disponibilitat de l'enllaç Terra-Satèl·lit. Una de les millors tècniques de mitigació d'esvaïments contra la pluja és la diversitat de lloc, la qual aprofita l'estructura espacial de la pluja per contrarestar els seus efectes. En aquest treball, s'estudien tres escenaris diferents mitjançant simulacions amb time-series d'atenuació de pluja a 20 GHz per tal d'avaluar l'eficàcia de la diversitat de lloc múltiple en termes de propagació des d'una petita escala fins a una gran escala. Els resultats mostren que els requeriments tècnics en termes de potència transmesa o guany d'antena de les estacions terrestres es poden relaxar per mantenir una comunicació fiable més del 99.99 % del temps gràcies a la significativa millora introduïda per la diversitat o aconseguir major disponibilitat amb l'ús del equip

Repair algorithms and penalty functions to handling constraints in an evolutionary scheduling

Ecosystems are directly and negatively affected by many industrial risky activities such as the oil transportation and exploitation. It is therefore important that oil companies carry out a correct maintenance of their oil fields. In this work we implement in our previously proposed evolutionary optimization tool (called PAE) a set of constraint-handling techniques to solve a constrained version of the maintenance problem. The results and comparisons demonstrated that the proposed repair algorithm required less computational effort (evaluations) with the same quality of solutions for the set of instances used.Presentado en XI Workshop Agentes y Sistemas Inteligentes (WASI)Red de Universidades con Carreras en Informática (RedUNCI

Kidney transplantation and COVID-19 renal and patient prognosis

Coronavirus disease 2019 (COVD-19) emerged as a pandemic in December 2019. Infection has spread quickly and renal transplant recipients receiving chronic immunosuppression have been considered a population at high risk of infection, complications and infection-related death. During this year a large amount of information from nationwide registries, multicentre and single-centre studies have been reported. The number of renal transplant patients diagnosed with COVID-19 was higher than in the general population, but the lower threshold for testing may have contributed to its better identification. Major complications such as acute kidney injury and acute respiratory distress syndrome were very frequent in renal transplant patients, with a high comorbidity burden, but further studies are needed to support that organ transplant recipients receiving chronic immunosuppression are more prone to develop these complications than the general population. Kidney transplant recipients experience a high mortality rate compared with the general population, especially during the very early post-transplant period. Despite the fact that some studies report more favourable outcomes in patients with a kidney transplant than in patients on the kidney waiting list, the higher mortality described in the very early post-transplant period would advise against performing a kidney transplant in areas where the spread of infection is high, especially in recipients >60 years of age. Management of transplant recipients has been challenging for clinicians and strategies such as less use of lymphocyte-depleting agents for new transplants or anti-metabolite withdrawal and calcineurin inhibitor reduction for transplant patients with COVID-19 are not based on high-quality evidence

Proposed Definitions of Antibody-Mediated Rejection for Use as a Clinical Trial Endpoint in Kidney Transplantation

Antibody-mediated rejection; Biopsy; Kidney transplantationRechazo mediado por anticuerpos; Biopsia; Trasplante renalRebuig mediat per anticossos; Biòpsia; Trasplantament renalAntibody-mediated rejection (AMR) is caused by antibodies that recognize donor human leukocyte antigen (HLA) or other targets. As knowledge of AMR pathophysiology has increased, a combination of factors is necessary to confirm the diagnosis and phenotype. However, frequent modifications to the AMR definition have made it difficult to compare data and evaluate associations between AMR and graft outcome. The present paper was developed following a Broad Scientific Advice request from the European Society for Organ Transplantation (ESOT) to the European Medicines Agency (EMA), which explored whether updating guidelines on clinical trial endpoints would encourage innovations in kidney transplantation research. ESOT considers that an AMR diagnosis must be based on a combination of histopathological factors and presence of donor-specific HLA antibodies in the recipient. Evidence for associations between individual features of AMR and impaired graft outcome is noted for microvascular inflammation scores ≥2 and glomerular basement membrane splitting of >10% of the entire tuft in the most severely affected glomerulus. Together, these should form the basis for AMR-related endpoints in clinical trials of kidney transplantation, although modifications and restrictions to the Banff diagnostic definition of AMR are proposed for this purpose. The EMA provided recommendations based on this Broad Scientific Advice request in December 2020; further discussion, and consensus on the restricted definition of the AMR endpoint, is required.This initiative was supported by the European Society for Organ Transplantation

Proposed Definitions of T Cell-Mediated Rejection and Tubulointerstitial Inflammation as Clinical Trial Endpoints in Kidney Transplantation

T cell-mediated rejection; Kidney transplantation; OutcomesRebuig mediat per cèl·lules T; Trasplantament renal; ResultatsRechazo mediado por células T; Trasplante renal; ResultadosThe diagnosis of acute T cell-mediated rejection (aTCMR) after kidney transplantation has considerable relevance for research purposes. Its definition is primarily based on tubulointerstitial inflammation and has changed little over time; aTCMR is therefore a suitable parameter for longitudinal data comparisons. In addition, because aTCMR is managed with antirejection therapies that carry additional risks, anxieties, and costs, it is a clinically meaningful endpoint for studies. This paper reviews the history and classifications of TCMR and characterizes its potential role in clinical trials: a role that largely depends on the nature of the biopsy taken (indication vs protocol), the level of inflammation observed (e.g., borderline changes vs full TCMR), concomitant chronic lesions (chronic active TCMR), and the therapeutic intervention planned. There is ongoing variability—and ambiguity—in clinical monitoring and management of TCMR. More research, to investigate the clinical relevance of borderline changes (especially in protocol biopsies) and effective therapeutic strategies that improve graft survival rates with minimal patient morbidity, is urgently required. The present paper was developed from documentation produced by the European Society for Organ Transplantation (ESOT) as part of a Broad Scientific Advice request that ESOT submitted to the European Medicines Agency for discussion in 2020. This paper proposes to move toward refined definitions of aTCMR and borderline changes to be included as primary endpoints in clinical trials of kidney transplantation.This initiative was supported by the European Society for Organ Transplantation

Change in Estimated GFR and Risk of Allograft Failure in Patients Diagnosed With Late Active Antibody-mediated Rejection Following Kidney Transplantation

Malaltia renal en fase terminal; Trasplantament de ronyóEnfermedad renal en etapa terminal; Transplante de riñónEnd-stage renal disease; Kidney TransplantBackground. There are challenges in designing adequate, well-controlled studies of patients with active antibody-mediated rejection (AMR) after kidney transplantation (KTx). Methods. We assessed the functional relationship between change in estimated glomerular filtration rate (eGFR) following the diagnosis of AMR and the risk of subsequent death-censored graft failure using the joint modeling framework. We included recipients of solitary KTx between 1995 and 2013 at 4 transplant centers diagnosed with biopsy-proven active AMR at least 1 year post-KTx, who had a minimum of 3-year follow-up. Results. A total of 91 patients across participating centers were included in the analysis. Of the 91 patients, n = 54 patients (59%) met the death-censored graft failure endpoint and n = 62 patients (68%) met the all-cause graft failure composite endpoint. Kaplan-Meier death-censored graft survival rates at 12, 36, and 60 months postdiagnosis of AMR pooled across centers were 88.9%, 58.9%, and 36.4%, respectively. Spaghetti plots indicated a linear trend in the change in eGFR, especially in the first 12 months postdiagnosis of active AMR. A significant change in eGFR was observed within the first 12 months postdiagnosis of active AMR, getting worse by a factor of −0.757 mL/min/1.73 m2 per month during the 12-month analysis period (a delta of −9.084 mL/min/1.73 m2 at 1 y). Notably, an extrapolated 30% improvement in the slope of eGFR in the first 12 months was associated with a 10% improvement in death-censored graft failure at 5 years. Conclusions. If prospectively validated, this study may inform the design of pivotal clinical trials for therapies for late AMR

Renal Biopsy in Type 2 Diabetic Patients

The majority of diabetic patients with renal involvement are not biopsied. Studies evaluating histological findings in renal biopsies performed in diabetic patients have shown that approximately one third of the cases will show pure diabetic nephropathy, one third a non-diabetic condition and another third will show diabetic nephropathy with a superimposed disease. Early diagnosis of treatable non-diabetic diseases in diabetic patients is important to ameliorate renal prognosis. The publication of the International Consensus Document for the classification of type 1 and type 2 diabetes has provided common criteria for the classification of diabetic nephropathy and its utility to stratify risk for renal failure has already been demonstrated in different retrospective studies. The availability of new drugs with the potential to modify the natural history of diabetic nephropathy has raised the question whether renal biopsies may allow a better design of clinical trials aimed to delay the progression of chronic kidney disease in diabetic patients

Comportamiento de un cluster heterogéneo de CPUs y GPUs para el trazado de rayos

El objetivo de este PFC es realizar la adaptación de un trazador de rayos al cálculo en paralelo sobre varias computadoras conectadas en red y estudiar su comportamiento y el rendimiento conseguido