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- Novel compound heterozygous mutations in SLC5A2 are responsible for autosomal recessive renal glucosuria.Publication . Calado, J; Soto, K; Clemente, C; Correia, P; Rueff, JFamilial renal glucosuria is an inherited renal tubular disorder. A homozygous nonsense mutation in the SLC5A2 gene, encoding the sodium/glucose co-transporter SGLT2, has recently been identified in an affected child of consanguineous parents. We now report novel compound heterozygous mutations in the son of non-consanguineous parents. One allele has a p.Q167fsX186 mutation, which is expected to produce a truncated protein, and the other a p.N654S mutation involving a highly conserved residue. These findings confirm that mutations in the SLC5A2 gene are responsible for recessive renal glucosuria.
- Demographic and clinical characteristics of patients receiving dialysis in Portugal: a nationwide multicentre surveyPublication . Lopes, J; Abreu, F; Almeida, E; Carvalho, B; Carmo, C; Carvalho, D; Barber, E; Costa, F; Silva, G; Boquinhas, H; Silva, J; Inchaustegui, L; Dias, L; Batista, M; Neves, P; Mendes, TBackground. Data on human immunodeficiency virus (HIV) infected patients receiving dialysis in Portugal is scarce. Methods. This nationwide epidemiological survey retrospectively evaluates HIV-infected patients on chronic dialysis in Portugal between 1997 and 2002. Results. Sixty-six patients were evaluated (mean age: 39.1±1.6 years, 47 men, 35 black African). Sixty-two patients started dialysis and 4 patients who were receiving dialysis had HIV seroconversion. Eighty-five percent of patients were treated in Lisbon. The annual incidence of HIV-infected patients on chronic dialysis was 0.5% in 1997 and 0.9% in 2002. Seventy-eight percent of patients were HIV-1 infected , 13% had hepatitis B and 31% hepatitis C. Sexual contact was the mode of transmission of HIV in 53% of cases. Four patients had biopsy-proved HIV-associated nephropathy. Ninety-five percent of patients were on chronic hemodialysis. Fifty percent of patients had acquired immunodeficiency syndrome. At follow-up, 12 patients died. HIV-infected CKD patient survival after starting dialysis was 80% at 3 years. Conclusion. The incidence of HIV-infected patients on chronic dialysis in Portugal has almost doubled. Widespread use of highly active antiretroviral therapy and the increasing number of black Africans from former overseas Portuguese colonies now living in Portugal are possible reasons for this large increase.
- Model-based analysis of FGF23 regulation in chronic kidney diseasePublication . Yokota, H; Pires, A; Raposo, J; Ferreira, HThe mechanism of FGF23 action in calcium/phosphorus metabolism of patients with chronic kidney disease (CKD) was studied using a mathematical model and clinical data in a public domain. We have previously built a physiological model that describes interactions of PTH, calcitriol, and FGF23 in mineral metabolism encompassing organs such as bone, intestine, kidney, and parathyroid glands. Since an elevated FGF23 level in serum is a characteristic symptom of CKD patients, we evaluate herein potential metabolic alterations in response to administration of a neutralizing antibody against FGF23. Using the parameters identified from available clinical data, we observed that a transient decrease in the FGF23 level elevated the serum concentrations of PTH, calcitriol, and phosphorus. The model also predicted that the administration reduced a urinary output of phosphorous. This model-based prediction indicated that the therapeutic reduction of FGF23 by the neutralizing antibody did not reduce phosphorus burden of CKD patients and decreased the urinary phosphorous excretion. Thus, the high FGF23 level in CKD patients was predicted to be a failure of FGF23-mediated phosphorous excretion. The results herein indicate that it is necessary to understand the mechanism in CKD in which the level of FGF23 is elevated without effectively regulating phosphorus.
- Familial C4B deficiency and immune complex glomerulonephritisPublication . Soto, K; Wu, Y; Ortiz, A; Aparício, S; Yu, CHomozygous complement C4B deficiency is described in a Southern European young female patient with Membranoproliferative Glomerulonephritis (MPGN) type III characterized by renal biopsies with strong complement C4 and IgG deposits. Low C4 levels were independent of clinical evolution or type of immunosuppression and were found in three other family members without renal disease or infections. HLA typing revealed that the patient has homozygous A*02, Cw*06, B*50 at the class I region, and DRB1*08 and DQB1*03 at the class II region. Genotypic and phenotypic studies demonstrated that the patient has homozygous monomodular RCCX in the HLA class III region, with single long C4A genes coding for C4A3 and complete C4B deficiency. Her father, mother, son and niece have heterozygous C4B deficiency. The patient's deceased brother had a history of Henoch-Schönlein Purpura (HSP), an immune complex-mediated proliferative glomerulonephritis. These findings challenge the putative pathophysiological roles of C4A and C4B and underscore the need to perform functional assays, C4 allotyping and genotyping on patients with persistently low serum levels of a classical pathway complement component and glomerulopathy associated with immune deposits.
- Nephrolithiasis is associated with an increased prevalence of cardiovascular diseasePublication . Domingos, F; Serra, MABackground: Nephrolithiasis has been associated with hypertension, obesity and diabetes Mellitus. The prevalence of adverse cardiovascular outcomes among kidney stone formers (KSF) is unknown. Methods: We examined the IV Portuguese National Health Survey for documenting possible associations between nephrolithiasis, cardiovascular diseases, diabetes and obesity in the Portuguese adult population. Results: We obtained 23,349 questionnaires from individuals with ≥ 15 year-old. The prevalence of kidney stone disease was 7.3%. The prevalence of hypertension was higher among KSF when compared with the general population (50.4% vs. 30.2%; p < 0,001). Age and obesity significantly increase the risk for nephrolithiasis. After adjusting for age and body mass index, KSF have higher prevalence of hypertension (odds-ratio: 1.841; 95% CI: 1.651 – 2.053), diabetes Mellitus (odds-ratio: 1.475; 95% CI: 1.283 – 1.696; p < 0.001), myocardial infarction (odds-ratio: 1.338; 95% CI: 1.003 – 1.786; p < 0.05), and stroke (odds-ratio: 1.330; 95% CI: 1.015 – 1.743; p < 0.05) as compared with non-stone formers. Conclusions: Kidney stone disease is associated with a higher prevalence of chronic diseases and adverse cardiovascular outcomes when compared with the general population.
- Endovascular management of non maturing dyalisis vascular accessPublication . Pinto, E; Madeira, C; Sousa, M; Penha, D; Rosa, L; Germano, A; Baptista, M
- Quiz page June 2012: kidney failure in an HIV-positive patientPublication . Coelho, S; Aparício, S; Manso, RT; Soto, K
- A mathematical model of calcium and phosphorus metabolism in two forms of hyperparathyroidism.Publication . Raposo, J; Pires, A; Yokota, H; Ferreira, HParathyroid hormone (PTH) plays a critical role in calcium and phosphorus metabolism. Interestingly, in two forms of hyperparathyroidism (excessive amount of PTH in the serum), the metabolic disturbances in patients with chronic kidney disease (CKD) significantly differ from those with primary hyperparathyroidism (PHP). Since an intuitive understanding of these PTH-linked regulatory mechanisms are hardly possible, we developed a mathematical model using clinical data (1586 CKD and 40 PHP patients). The model was composed of a set of ordinary differential equations, in which the regulatory mechanism of PTH together with other key factors such as 1,25-Dihydroxyvitamin D (1,25(OH)₂D) and calcium was described in the tissues including bone, the kidney, the serum, and the parathyroid glands. In this model, an increase in PTH was induced by its autonomous production in PHP, while PTH in CKD was elevated by a decrease in feedback inhibition of 1,25(OH)₂D in the serum, as well as an increase in stimulation by phosphorus in the serum. The model-based analysis revealed characteristic differences in the outcomes of hyperparathyroidism in CKD and PHP. The calcium exchange in bone, for instance, was predicted significantly higher in PHP than CKD. Furthermore, we evaluated the observed and predicted responses to the administration of calcimimetics, a recently developed synthetic drug that modulated efficacy of calcium-sensing receptors. The results herein support the notion that the described model would enable us to pose testable hypotheses about the actions of PTH, providing a quantitative analytical tool for evaluating treatment strategies of PHP and CKD.
- Plasma NGAL for the diagnosis of AKI in patients admitted from the emergency department settingPublication . Soto, K; Papoila, A; Coelho, S; Bennett, M; Ma, Q; Rodrigues, B; Fidalgo, P; Frade, F; Devarajan, PBACKGROUND AND OBJECTIVES: The purpose of this study was to determine the accuracy of plasma neutrophil gelatinase-associated lipocalin as a marker of AKI in patients admitted from the emergency department. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this prospective cohort study, patients (n=616) admitted from the emergency department from March to November of 2008 were classified according to clinical criteria as AKI, transient azotemia, stable CKD, and normal function. Plasma neutrophil gelatinase-associated lipocalin was measured serially. A logistic regression model using clinical characteristics was fitted to the data, and a second model included discretized plasma neutrophil gelatinase-associated lipocalin. Performance of the models was evaluated by Hosmer-Lemeshow goodness-of-fit test, area under the receiver operating characteristic curve, net reclassification improvement, integrated discrimination improvement, and predictiveness curve. RESULTS: Twenty-one percent of patients were classified as AKI; the highest median levels of plasma neutrophil gelatinase-associated lipocalin were in the AKI group (146-174 ng/ml at various time points) and increased with AKI severity (207-244 ng/ml for Acute Kidney Injury Network classification stage>2). The discriminative ability of plasma neutrophil gelatinase-associated lipocalin for AKI diagnosis (area under the curve, 0.77-0.82 at various time points) improved with higher grades of severity (area under the curve, 0.85-0.89 for AKIN>2). Plasma neutrophil gelatinase-associated lipocalin discriminated AKI from normal function and transient azotemia (area under the curve, 0.85 and 0.73, respectively). Patients were classified into three grades of AKI risk according to plasma neutrophil gelatinase-associated lipocalin levels (low, moderate [i.e., the gray zone], and high). Patients with plasma neutrophil gelatinase-associated lipocalin in the high-risk category displayed a 10-fold greater risk of AKI (odds ratio, 9.8; 95% confidence interval, 5.6 to 16.9). The addition of plasma neutrophil gelatinase-associated lipocalin to the clinical model yielded a net reclassification improvement of 94.3% and an integrated discrimination improvement of 0.122. CONCLUSION: Plasma neutrophil gelatinase-associated lipocalin is an accurate biomarker for prediction of AKI in patients admitted from the emergency department. This work proposes a three-grade classification of AKI risk based on plasma neutrophil gelatinase-associated lipocalin levels.
- Candida species contamination of preservation fluid-outcome of renal transplantation in 6 patientsPublication . Rodrigues, B; Natário, A; Vizinho, R; Jorge C, C; Weigert, A; Martinho, A; Toscano, C; Marques, T; Machado, DBACKGROUND: Fungal infections are a rare but important cause of morbidity and mortality in kidney transplantation. Fungal contamination of the kidney preservation fluid may, sometimes, be the cause of these infections. However, the clinical consequences of fungal contamination of this fluid are not completely understood and literature on this topic is controversial. The purpose of this study was to determine the incidence of preservation fluid contamination by fungi and its clinical consequences. METHODS: From June 2010 to September 2011, a prospective cohort analysis was conducted at our center, enrolling all patients who received a renal allograft and whose perfusion fluid was analyzed for microbiology sterility. Patients with perfusion fluids positive for fungi were further studied: the patients' status was assessed during regular visits and data were recorded, including clinical characteristics, infections, graft function, immunosuppressive regimen and outcomes. RESULTS: Microbiologic, cultures of 70 kidney perfusion fluids using specific mycologic media, obtained from 74 cadaveric renal transplants (4 fluids were unsuitable for analysis), were evaluated. Six samples were positive for yeasts (8.6%), with 4 isolates of Candida albicans and 2 isolates of Candida glabrata. Four patients had no evidence of fungal infection during the follow-up period (median 321 days); conversely, 2 patients developed severe mycotic vascular complications leading to transplantectomy. CONCLUSIONS: Perfusion fluid contamination by fungi is an elusive situation that can lead either to an unremarkable clinical course or to graft loss life-threatening situations. Routine culture of kidney perfusion fluid is critical for prompt diagnosis and early implementation of appropriate treatment.