A New Cycler for Automated Peritoneal Dialysis to Provide Efficient Dialysis and Improved Sleep Quality.

INTRODUCTION: Automated peritoneal dialysis (APD) employs cyclers to control inflow and outflow of the dialysis fluid to the patient's abdomen. To allow more patients to use this modality, cyclers should support the achievement of an adequate dialysis dose and be easy to use, cost-effective, and silent. The new SILENCIA cycler (Fresenius Medical Care, Bad Homburg, Germany), designed to improve these characteristics in comparison to its predecessor device, was evaluated in this respect in a prospective study. METHODS: This cross-over study comprised two 2-week study periods, separated by a 3-week training phase. First, patients underwent APD with their current cycler (PD-NIGHT [Fresenius Medical Care, Bad Homburg, Germany] or HomeChoice Pro [Baxter, Deerfield, IL, USA] as control), followed by training on the SILENCIA cycler. Then, patients were switched to the SILENCIA cycler. During each treatment period, we collected data on total Kt/Vurea, ultrafiltration (UF) volume, patient-reported outcomes (sleep quality, among others), and device handling. RESULTS: Sixteen patients were enrolled; 2 patients terminated the study prematurely before study intervention, 1 patient due to a protocol violation. In 13 patients, total Kt/Vurea and UF could be evaluated. Neither Kt/Vurea nor UF differed significantly between control and SILENCIA cyclers. Out of 10 patients answering the questionnaire on sleep quality after the 2-week phase with the SILENCIA cycler, sleep quality improved in 5 patients; in the other patients, sleep quality was rated unchanged compared to the previously used cycler. The average reported sleep time was 5.9 ± 1.8 h with the PD-NIGHT, 7.2 ± 2.1 h with HomeChoice Pro, and 8.0 ± 1.6 h with the SILENCIA cycler. All patients were much or very much satisfied with the new cycler. CONCLUSION: The SILENCIA cycler delivers adequate urea clearance and UF. Importantly, sleep quality improved, possibly related to less caution messages and alarms.

Efficacy of vaccination against the SARS-CoV-2 virus in patients with chronic kidney disease on hemodialysis.

SARS-CoV-2 has had a great impact on world health, patients on hemodialysis have a higher rate of infection and death due to COVID-19. Vaccination is important to control infection and improve the prognosis of infected patients. To describe the efficacy of vaccination against SARS-CoV-2 in Chilean patients on hemodialysis during the year 2021. Retrospective observational study. A total of 9,712 clinical records were reviewed. Data were presented as summary measures. Fisher's exact test, Mann-Whitney U test, and multivariate logistic regression were used for the analysis. Risk and survival analysis were calculated, considering a statistical significance of less than 0.05. The average age of the patients attended was 61.5 ± 14.6 years. Average time on dialysis 67.6 months and 35.0% diabetic. 93.2% of patients were vaccinated against SARS-CoV-2, 70.7% of them received booster doses. The risk of infection was higher for those who received one or no dose, compared to those who received booster doses against SARS-CoV-2: OR = 252.46 [165.13; 401.57]. Of the infected patients, 15.7% died from COVID-19. The risk of death was higher in unvaccinated or single-dose patients compared to those vaccinated with two doses: OR = 2.64 [2.23; 3.12]. Patients with two doses and a booster had a longer survival compared to those who received one or no dose of vaccination against SARS-CoV-2 (p < .05). The vaccination in Chile, which started in February 2021, has demonstrated that booster doses against SARS-CoV-2 significantly reduced the risk of infection, hospitalization, and death due to COVID-19 in patients on hemodialysis.

Clinical Efficacy of SARS-CoV-2 Vaccination in Hemodialysis Patients.

Introduction: The COVID-19 pandemic is a global public health problem. Patients with end-stage renal disease on hemodialysis are at a higher risk of infection and mortality than the general population. Worldwide, a vaccination campaign has been developed that has been shown to reduce severe infections and deaths in the general population. However, there are currently limited data on the clinical efficacy of vaccinations in the hemodialysis population. Methods: A national multicenter observational cohort was performed in Chile to evaluate the clinical efficacy of anti-SARS-CoV-2 vaccination in end-stage renal disease patients on chronic hemodialysis from February 2021 to August 2021. In addition, the BNT162b2 (Pfizer-BioNTech) and CoronaVac (Sinovac) vaccines were evaluated. The efficacy of vaccination in preventing SARS-CoV-2 infection, hospitalizations, and deaths associated with COVID-19 was determined. Results: A total of 12,301 patients were evaluated; 10,615 (86.3%) received a complete vaccination (2 doses), 490 (4.0%) received incomplete vaccination, and 1196 (9.7%) were not vaccinated. During follow-up, 1362 (11.0%) patients developed COVID-19, and 150 died (case fatality rate: 11.0%). The efficacy of the complete vaccination in preventing infection was 18.1% (95% confidence interval [CI]:11.8-23.8%), and prevention of death was 66.0% (95% CI:60.6-70.7%). When comparing both vaccines, BNT162b2 and CoronaVac were effective in reducing infection and deaths associated with COVID-19. Nevertheless, the BNT162b2 vaccine had higher efficacy in preventing infection (42.6% vs. 15.0%) and deaths (90.4% vs. 64.8%) compared to CoronaVac. Conclusion: The results of our study suggest that vaccination against SARS-CoV-2 in patients on chronic hemodialysis was effective in preventing infection and death associated with COVID-19.

Survival study and factors associated with mortality in Chilean patients on peritoneal dialysis infected with SARS-CoV-2.

The Covid-19 pandemic has been responsible for millions of deaths worldwide. Patients with comorbidities- such as those on peritoneal dialysis (PD)- present higher morbidity and mortality than the general population. We prospectively evaluated all Chilean patients on PD (48 centres) and followed those who had Covid-19 from the beginning of the Covid-19 pandemic in Chile (March 2020) to January 2021 (start of vaccination campaign). We described demographic history, comorbidities, factors related to infection, need for hospitalisation and death due to Covid-19. During the study period, 106 adults on PD were infected by SARS-CoV-2, with a mean age of 53.1 (±16.3) and of which 53.9% were female. From that group, 54.8% required hospitalisation and 24.5% (n = 26) died due to Covid-19. Most of the patients (63.4%) were infected at home and 22.8% during hospitalisation for other reasons. There was a significant association for Covid-19 mortality with: being ≥60 years old, diabetes, time on PD ≥5 years, need for hospitalisation and hospital-acquired infection. At 90 days of follow-up, all deaths associated to Covid-19 occurred before 40 days. We conclude that patients on PD without Covid-19 vaccination have a high mortality and need for hospitalisation associated to Covid-19. To avoid this negative outcome, it is necessary to intensify strategies to avoid contagion, especially in those ≥60 years old, with diabetes and/or ≥5 years spent on PD.

MicrosimUC: Validation of a Low-Cost, Portable, Do-It-Yourself Microsurgery Training Kit.

BACKGROUND: Microsurgery depends largely on simulated training to acquire skills. Courses offered worldwide are usually short and intensive and depend on a physical laboratory. Our objective was to develop and validate a portable, low-cost microsurgery training kit. METHODS: We modified a miniature microscope. Twenty general surgery residents were selected and divided into two groups: (1) home-based training with the portable microscope (MicrosimUC, n = 10) and (2) the traditional validated microsurgery course at our laboratory (MicroLab, n = 10). Before the intervention, they were assessed making an end-to-end anastomosis in a chicken wing artery. Then, each member of the MicrosimUC group took a portable kit for remote skill training and completed an eight-session curriculum. The laboratory group was trained at the laboratory. After completion of training, they were all reassessed. Pre- and posttraining procedures were recorded and rated by two blind experts using time, basic, and specific scales. Wilcoxon's and Mann-Whitney tests were used to compare scores. The model was tested by experts (n = 10) and a survey was applied to evaluate face and content validity. RESULTS: MicrosimUC residents significantly improved their median performance scores after completion of training (p < 0.05), with no significant differences compared with the MicroLab group. The model was rated very useful for acquiring skills with 100% of experts considering it for training. Each kit had a cost of U.S. $92, excluding shipping expenses. CONCLUSION: We developed a low-cost, portable microsurgical training kit and curriculum with significant acquisition of skills in a group of residents, comparable to a formal microsurgery course.

Defects in t6A tRNA modification due to GON7 and YRDC mutations lead to Galloway-Mowat syndrome.

N6-threonyl-carbamoylation of adenosine 37 of ANN-type tRNAs (t6A) is a universal modification essential for translational accuracy and efficiency. The t6A pathway uses two sequentially acting enzymes, YRDC and OSGEP, the latter being a subunit of the multiprotein KEOPS complex. We recently identified mutations in genes encoding four out of the five KEOPS subunits in children with Galloway-Mowat syndrome (GAMOS), a clinically heterogeneous autosomal recessive disease characterized by early-onset steroid-resistant nephrotic syndrome and microcephaly. Here we show that mutations in YRDC cause an extremely severe form of GAMOS whereas mutations in GON7, encoding the fifth KEOPS subunit, lead to a milder form of the disease. The crystal structure of the GON7/LAGE3/OSGEP subcomplex shows that the intrinsically disordered GON7 protein becomes partially structured upon binding to LAGE3. The structure and cellular characterization of GON7 suggest its involvement in the cellular stability and quaternary arrangement of the KEOPS complex.

Clinical and genetic heterogeneity in familial steroid-sensitive nephrotic syndrome.

BACKGROUND: Familial steroid-sensitive nephrotic syndrome (SSNS) is a rare condition. The disease pathophysiology remains elusive. However, bi-allelic mutations in the EMP2 gene were identified, and specific variations in HLA-DQA1 were linked to a high risk of developing the disease. METHODS: Clinical data were analyzed in 59 SSNS families. EMP2 gene was sequenced in families with a potential autosomal recessive (AR) inheritance. Exome sequencing was performed in a subset of 13 families with potential AR inheritance. Two variations in HLA-DQA1 were genotyped in the whole cohort. RESULTS: Transmission was compatible with an AR (n = 33) or autosomal dominant (AD, n = 26) inheritance, assuming that familial SSNS is a monogenic trait. Clinical features did not differ between AR and AD groups. All patients, including primary (n = 7) and secondary steroid resistant nephrotic syndrone (SRNS), (n = 13) were sensitive to additional immunosuppressive therapy. Both HLA-DQA1 variations were found to be highly linked to the disease (OR = 4.34 and OR = 4.89; p < 0.001). Exome sequencing did not reveal any pathogenic mutation, neither did EMP2 sequencing. CONCLUSIONS: Taken together, these results highlight the clinical and genetic heterogeneity in familial SSNS. Clinical findings sustain an immune origin in all patients, whatever the initial steroid-sensitivity. The absence of a variant shared by two families and the HLA-DQA1 variation enrichments suggest a complex mode of inheritance.

Hereditary kidney diseases: highlighting the importance of classical Mendelian phenotypes.

A Mendelian inheritance underlies a nonnegligible proportion of hereditary kidney diseases, suggesting that the encoded proteins are essential for maintenance of the renal function. The identification of genes involved in congenital anomalies of the kidney and in familial forms of nephrotic syndrome significantly increased our understanding of the renal development and kidney filtration barrier physiology. This review will focus on the classical phenotype and clinical heterogeneity observed in the monogenic forms of these disorders. In addition, the role of susceptibility genes in kidney diseases with a complex inheritance will also be discussed.

Genotype-phenotype correlations in non-Finnish congenital nephrotic syndrome.

Mutations in NPHS1, which encodes nephrin, are the main causes of congenital nephrotic syndrome (CNS) in Finnish patients, whereas mutations in NPHS2, which encodes podocin, are typically responsible for childhood-onset steroid-resistant nephrotic syndrome in European populations. Genotype-phenotype correlations are not well understood in non-Finnish patients. We evaluated the clinical presentation, kidney histology, and disease progression in non-Finnish CNS cases by mutational screening in 107 families (117 cases) by sequencing the entire coding regions of NPHS1, NPHS2, PLCE1, WT1, LAMB2, PDSS2, COQ2, and NEPH1. We found that CNS describes a heterogeneous group of disorders in non-Finnish populations. We identified nephrin and podocin mutations in most families and only rarely found mutations in genes implicated in other hereditary forms of NS. In approximately 20% of cases, we could not identify the underlying genetic cause. Consistent with the major role of nephrin at the slit diaphragm, NPHS1 mutations associated with an earlier onset of disease and worse renal outcomes than NPHS2 mutations. Milder cases resulting from mutant NPHS1 had either two mutations in the cytoplasmic tail or two missense mutations in the extracellular domain, including at least one that preserved structure and function. In addition, we extend the spectrum of known NPHS1 mutations by describing long NPHS1 deletions. In summary, these data demonstrate that CNS is not a distinct clinical entity in non-Finnish populations but rather a clinically and genetically heterogeneous group of disorders.

Hereditary nephrotic syndrome: a systematic approach for genetic testing and a review of associated podocyte gene mutations.

Several genes have been implicated in genetic forms of nephrotic syndrome occurring in children. It is now known that the phenotypes associated with mutations in these genes display significant variability, rendering genetic testing and counselling a more complex task. This review will focus on the recent clinical findings associated with those genes known to be involved in isolated steroid-resistant nephrotic syndrome in children and, thereby, propose an approach for appropriate mutational screening. The recurrence of proteinuria after transplantation in patients with hereditary forms of nephrotic syndrome will also be discussed.

Analysis of recessive CD2AP and ACTN4 mutations in steroid-resistant nephrotic syndrome.

Mutations in podocyte genes have been identified in patients with steroid-resistant nephrotic syndrome (SRNS). Point mutations in the ACTN4 gene cause an autosomal dominant form of human focal segmental glomerular sclerosis (FSGS); however, reports of CD2AP mutations remain scarce. Based on the phenotype of Actn4 and Cd2ap null mice, we aimed to define the role of recessive CD2AP and ACTN4 mutations in a cohort of children with SRNS for which NPHS1, NPHS2, and PLCE1 mutations had been previously excluded. CD2AP and ACTN4 mutational analysis was performed in 42 children from 35 unrelated families. The median age of disease onset was 20 (range 0-102) months. Sixteen patients reached end-stage kidney disease at a median age of 84 (range 4-161) months. Renal histology showed FSGS lesions and minimal glomerular changes in 49% and 20% of patients, respectively. Microsatellite marker analysis excluded linkage to the CD2AP locus in 26 families and to the ACTN4 locus in 31 families. No disease-causing mutations were identified in the remaining families. Recessive CD2AP and ACTN4 mutations are rare in children with SRNS. The absence of mutations in this study suggests that there are other genetic causes of SRNS that still need to be identified.

Genetics of nephrotic syndrome: connecting molecular genetics to podocyte physiology.

Urinary losses of macromolecules in nephrotic syndrome (NS) reflect a dysfunction of the highly permselective glomerular filtration barrier. Genetic studies of hereditary forms of NS have led to the identification of proteins playing a crucial role in slit-diaphragm signalling, regulation of actin cytoskeleton dynamics, maintenance of podocyte integrity and cell-matrix interactions. This review will focus on recent molecular and clinical findings in the field of genetics of NS, thereby providing a better understanding of the complex glomerular filtration barrier physiology.

Genetics of nephrotic syndrome: new insights into molecules acting at the glomerular filtration barrier.

Nephrotic syndrome is caused by increased permeability of the glomerular filtration barrier for macromolecules. The identification of mutations of various podocyte-expressed proteins as causes of familial nephrotic syndrome has significantly contributed to shedding light into the molecular pathogenesis of nephrotic proteinuria and into the physiology of the glomerular sieve. More recent findings have changed our conception of the glomerular filtration barrier from a relatively static structure to a highly dynamic one. Both the multiprotein slit diaphragm complex around nephrin and the integrin receptor complex that mediates binding of the podocyte to the glomerular basement membrane, may translate outside-inside signaling and lead to podocyte actin cytoskeleton rearrangement. This may enable the podocyte network to adapt to environmental changes and respond to injury. Disturbance in these processes may not only be involved in the pathogenesis of hereditary nephrotic syndrome but also in that of more common acquired proteinuric diseases. Elucidation of the molecular mechanisms involved will possibly open the way to new therapeutic approaches.

Clinical and epidemiological assessment of steroid-resistant nephrotic syndrome associated with the NPHS2 R229Q variant.

Mutations of NPHS2, encoding podocin, are the main cause of autosomal recessive steroid-resistant nephrotic syndrome (NS) presenting in childhood. Adult-onset steroid-resistant NS has been described in patients heterozygous for a pathogenic NPHS2 mutation together with the p.R229Q variant. To determine the frequency and the phenotype of patients carrying the p.R229Q variant, we sequenced the complete coding region of NPHS2 in 455 families (546 patients) non-responsive to immunosuppressive therapy or without relapse after transplantation. Among affected Europeans, the p.R229Q allele was significantly more frequent compared to control individuals. Thirty-six patients from 27 families (11 families from Europe and 14 from South America) were compound heterozygotes for the p.R229Q variant and one pathogenic mutation. These patients had significantly later onset of NS and end stage renal disease than patients with two pathogenic mutations. Among 119 patients diagnosed with NS presenting after 18 years of age, 18 patients were found to have one pathogenic mutation and p.R229Q, but none had two pathogenic mutations. Our study shows that compound heterozygosity for p.R229Q is associated with adult-onset steroid-resistant NS, mostly among patients of European and South American origin. Screening for the p.R229Q variant is recommended in these patients along with further NPHS2 mutation analysis in those carrying the variant.

Streptococcus viridans-associated peritonitis after gastroscopy.

Transient bacteremia during and after endoscopic procedures is a well-documented phenomenon. Streptococcus viridans peritonitis is frequently associated with peritoneal dialysis, and the infection is probably attributable to hematogenous spread, dental procedures, or transluminal contamination with oral flora. To our knowledge, no reports exist of peritonitis occurring after gastroscopy in peritoneal dialysis patients. Here, we report the case of a 69-year-old male patient receiving automated peritoneal dialysis who required emergency gastroscopy and sclerotherapy plus heat-probe coagulation to control active bleeding from a duodenal ulcer The next day, this patient developed nausea and abdominal pain. The diagnosis of peritonitis was made based on a cloudy peritoneal effluent and a leukocyte count of 11,500 cells/microL with 98% neutrophils. S. viridans was identified in the peritoneal fluid culture. The patient received ceftazidime for 14 days, followed by clarithromycin for 7 days, and he recovered successfully. Patients receiving peritoneal dialysis who undergo esophagogastroduodenal endoscopy are at risk to develop peritonitis, and so antibiotic prophylaxis is desirable.

Stenotrophomonas maltophilia peritonitis in a patient receiving automated peritoneal dialysis.

Stenotrophomonas maltophilia is increasingly being recognized as an important cause of nosocomial infection. S. maltophilia peritonitis is a rare complication of chronic peritoneal dialysis. Here, we report the case of a 54-year-old female with end-stage renal disease treated with automated peritoneal dialysis. The patient had no previous history of peritonitis or catheter exit-site infection. She presented with fever, abdominal pain, and cloudy peritoneal effluent. The organism isolated from the effluent was S. maltophilia. The patient received trimethoprim 320 mg and sulfamethoxazole 1600 mg for 6 weeks, plus amikacin 200 mg for 14 days. She recovered completely, with no need for catheter removal. No recurrence was observed.

Successful treatment of Nocardia asteroides peritonitis in a patient undergoing automated peritoneal dialysis and receiving immunosuppressive therapy.

Nocardiosis is an opportunistic infection especially in patients with underlying chronic debilitating disease or immunodeficiency. Nocardia peritonitis is an uncommon infection in peritoneal dialysis patients. Here, we report a case of peritonitis by Nocardia asteroides during automated peritoneal dialysis in a 35-year-old male patient who had prolonged immunosuppressive therapy to treat acute rejection of a nonfunctioning kidney allograft. The patient presented at our outpatient clinic with typical symptoms of acute peritonitis. The peritoneal fluid leukocyte count was 20,500 cells/microL, with 90% neutrophils. Gram staining showed gram-positive filamentous bacilli later identified as N. asteroides. After bacterial identification, the patient received trimethoprim 320 mg and sulfamethoxazole 3200 mg intravenously every 48 hours (TMP-SMX), plus amikacin 100 mg intraperitoneally daily. The immunosuppressive therapy was reduced. Peritoneal fluid cultures became negative after 1 week of treatment, concomitant with clinical improvement. Unfortunately, after 5 weeks of therapy, the patient developed hematologic side effects attributable to the TMP-SMX treatment. The TMP-SMX was suspended at that time, and the patient then received cefuroxime 500 mg by mouth and amikacin 100 mg intraperitoneally daily for a total of 12 weeks. The patient recovered completely and was discharged 3 months after onset of the peritonitis. Prolonged antibiotic therapy without catheter removal has not been previously described in immunosuppressed patients with APD peritonitis. The combination of amikacin and TMP-SMX may be safe and effective in APD patients who develop N. asteroides peritonitis.