José Carlos Oliveira

Evaluation of peritoneal transport and membrane status in peritoneal dialysis: focus on incident fast transporters.

Background/Aim: The determinants of baseline fast solute transport are still unclear. We prospectively investigated the relationship of peritoneal solute transport with markers of inflammation, angiogenesis, and membrane status, with a focus on fast transporters. Methods: Seventy-one incident peritoneal dialysis patients were assessed with baseline and annual peritoneal equilibration tests, using a 3.86% glucose dialysis solution. Residual renal function and markers of inflammation, including systemic and intraperitoneal interleukin-6 (IL-6), effluent cancer antigen 125 (CA-125), and vascular endothelial growth factor (VEGF) appearance rates (ARs), were investigated. The time course of the dialysate-to-plasma ratio of creatinine (D/P creatinine ratio) and its relationship with the biomarkers were investigated by a mixed linear model. Results: Incident fast/fast average transporters had a similar age, diabetes prevalence, and serum and effluent IL-6 levels, but significantly higher levels of CA-125 and VEGF ARs than the slow/slow average group; the D/P creatinine ratio was not correlated with systemic IL-6, but was correlated with effluent CA-125 AR (r = 0.45, p < 0.0001) and VEGF AR (r = 0.52, p < 0.0001). The D/P creatinine ratio decreased with a U-shaped profile (p = 0.02). Intraperitoneal IL-6 was the significant and positive determinant of the time course of the D/P creatinine ratio (p < 0.0001). Effluent CA-125 decreased with time on peritoneal dialysis (p = 0.013). Conclusions: Baseline peritoneal fast transport was not associated with systemic inflammation, but was related to peritoneal locally produced substances able to mediate transitory hyperpermeability. The D/P creatinine ratio changed during the follow-up period with a U-shaped profile. This was associated with effluent IL-6 and partly with VEGF. CA-125 decreased throughout the follow-up period.

Urinary ATP May Be a Dynamic Biomarker of Detrusor Overactivity in Women with Overactive Bladder Syndrome

Background Nowadays, there is a considerable bulk of evidence showing that ATP has a prominent role in the regulation of human urinary bladder function and in the pathophysiology of detrusor overactivity. ATP mediates nonadrenergic-noncholinergic detrusor contractions in overactive bladders. In vitro studies have demonstrated that uroepithelial cells and cholinergic nerves from overactive human bladder samples (OAB) release more ATP than controls. Here, we compared the urinary ATP concentration in samples collected non-invasively from OAB women with detrusor overactivity and age-matched controls. Methods Patients with neurologic diseases, history of malignancy, urinary tract infections or renal impairment (creatinine clearance <70 ml/min) were excluded. All patients completed a 3-day voiding diary, a 24 h urine collection and blood sampling to evaluate creatinine clearance. Urine samples collected during voluntary voids were immediately freeze-preserved for ATP determination by the luciferin-luciferase bioluminescence assay; for comparison purposes, samples were also tested for urinary nerve growth factor (NGF) by ELISA. Results The urinary content of ATP, but not of NGF, normalized to patients’ urine creatinine levels (ATP/Cr) or urinary volume (ATP.Vol) were significantly (P<0.05) higher in OAB women with detrusor overactivity (n = 34) than in healthy controls (n = 30). Significant differences between the two groups were still observed by boosting urinary ATP/Cr content after water intake, but these were not detected for NGF/Cr. In OAB patients, urinary ATP/Cr levels correlated inversely with mean voided volumes determined in a 3-day voiding diary. Conclusion A high area under the receiver operator characteristics (ROC) curve (0.741; 95% CI 0.62–0.86; P<0.001) is consistent with urinary ATP/Cr being a highly sensitive dynamic biomarker for assessing detrusor overactivity in women with OAB syndrome.

T-cell receptor repertoire in hereditary hemochromatosis: a study of 32 hemochromatosis patients and 274 healthy subjects.

Low CD8(+) T lymphocyte numbers have contributed to deciphering the genotype/phenotype discrepancies found in hereditary hemochromatosis (HH) patients genotyped for the Hfe mutations, C282Y and H63D. In this study, we extend the analysis of T lymphocytes in HH to the T cell receptor (TcR) repertoire. Thirty-two HH patients (C282Y homozygous) and 274 Hfe genotyped healthy subjects were studied. The following TcR chains were analyzed: Valpha2.3, Vbeta5.1, Vbeta5.2, Vbeta5.3, Vbeta6.7, Vbeta8, and Vbeta12 among the CD4(+) and CD8(+) populations. Lymphopenias and absence of expansions of the Vbeta5.2 and Vbeta12 chains in the CD8(+) pool were seen in controls heterozygous for the C282Y mutation. Expansions in the control group were seen within the CD8(+) pool and were rare/absent within the CD4(+) pool. TcR expansions were found more frequent in patients with iron overload related pathology than in patients without pathology. 9/16 of the patients with pathology have at least one expansion among the CD8(+) pool a number significantly higher compared with patients without pathology (1/16). These findings suggest that Hfe has an effect in the shaping of T-cell populations either directly, as indicated by the lymphopenia seen in the two chains in C282Y heterozygous without iron overload, or indirectly by contributing to iron overload pathology.

Clinical and genetic heterogeneity in hereditary haemochromatosis: association between lymphocyte counts and expression of iron overload.

Abstract: To identify a new marker of expression of disease, independent of HFE genotype in patients with hereditary haemochromatosis (HHC), the total peripheral blood lymphocyte counts were analysed according to iron status in two groups of subjects with HFE mutations. The groups consisted of 38 homozygotes for C282Y, and 107 heterozygotes for the C282Y or compound heterozygotes for C282Y and H63D. For control purposes, total lymphocyte counts and iron status were also examined in 20 index patients with African dietary iron overload, a condition not associated with HFE mutations, and in 144 members of their families and communities. Mean lymphocyte numbers were lower in C282Y homozygous HHC index subjects with cirrhosis and higher iron stores than in those without cirrhosis and with lower iron burdens [(1.65 ± 0.43) × 106/mL vs. (2.27 ± 0.49) × 106/mL; p = 0.008]. Similarly, mean lymphocyte counts were significantly lower in C282Y heterozygotes and C282Y/H63D compound heterozygotes with iron overload and increased serum ferritin concentrations compared to those with normal serum ferritin concentrations (p < 0.05). Statistically significant negative correlations were found, in males, between lymphocyte counts and the total body iron stores, either in C282Y homozygous HHC patients (p = 0.031 in a multiple regression model dependent on age) and in C282Y heterozygotes or C282Y/H63D compound heterozygotes with iron overload (p = 0.029 in a simple linear model). In contrast, lymphocyte counts increased with increasing serum ferritin concentrations among the index subjects with African iron overload (r = 0.324, not statistically significant) and among the members of their families and communities (r = 0.170, p = 0.042). These results suggest that a lower peripheral blood lymphocyte count is associated with a greater degree of iron loading in HFE haemochromatosis but not in African iron overload, and they support the notion that the lymphocyte count may serve as a marker of a non‐HFE gene that influences the clinical expression of HFE haemochromatosis.

Neutrophil Gelatinase-Associated Lipocalin in Kidney Transplantation Is an Early Marker of Graft Dysfunction and Is Associated with One-Year Renal Function

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) has been suggested as potential early marker of delayed graft function (DGF) following kidney transplantation (KTx). We conducted a prospective study in 40 consecutive KTx recipients to evaluate serial changes of uNGAL within the first week after KTx and assess its performance in predicting DGF (dialysis requirement during initial posttransplant week) and graft function throughout first year. Urine samples were collected on post-KTx days 0, 1, 2, 4, and 7. Linear mixed and multivariable regression models, receiver-operating characteristic (ROC), and areas under ROC curves were used. At all-time points, mean uNGAL levels were significantly higher in patients developing DGF (n = 18). Shortly after KTx (3–6 h), uNGAL values were higher in DGF recipients (on average +242 ng/mL, considering mean dialysis time of 4.1 years) and rose further in following days, contrasting with prompt function recipients. Day-1 uNGAL levels accurately predicted DGF (AUC-ROC = 0.93), with a performance higher than serum creatinine (AUC-ROC = 0.76), and similar to cystatin C (AUC-ROC = 0.95). Multivariable analyses revealed that uNGAL levels at days 4 and 7 were strongly associated with one-year serum creatinine. Urinary NGAL is an early marker of graft injury and is independently associated with dialysis requirement within one week after KTx and one-year graft function.

Peritoneal Membrane Evaluation in Routine Clinical Practice

Background/Aims: Establishment of reference values for small solute transport, sodium sieving and effluent CA125 with 3.86% (4 h) peritoneal equilibration test (PET), and comparison with fast-fast PET with regard to small solute transport categories. Methods: Cross-sectional study; 69 prevalent patients. Sodium sieving corrected for sodium diffusion with a formula applicable to the PET. CA125 appearance rate (AR) was measured. Expected and observed 60 min D/Pcreatinine were compared by Bland and Altman. Results: Means (95% CI): D/Pcreatinine 0.73 (0.70–0.76), MTACcreatinine 9.6 (8.4–10.9) ml/min, D/D₀ glucose 0.30 (0.28–0.31), corrected dip 0.17 (0.15–0.18), CA125 150 (125–176) U/min. Both corrected and uncorrected sodium sieving were informative. Peritoneal transport was faster at 60 min dwell. UFF patients presented very low corrected dip and CA125 AR. Conclusion: 3.86% (4 h) PET provided results similar to those from SPA. Correction for diffusion of sodium sieving is dispensable for simple clinical evaluations. D/Pcreatinine at 60 min overestimated small solute transport rate. Effluent CA125 was consistently lower in UFF patients.

Leptin and Adiponectin During the First Week After Kidney Transplantation: Biomarkers of Graft Dysfunction?

CONTEXT AND OBJECTIVE Based on evidence that leptin and adiponectin are removed from circulation primarily by the kidney, we designed a study to examine the longitudinal changes of these adipokines during the first week after kidney transplantation (KTx) and to test the hypothesis that higher levels of leptin and/or adiponectin could be early biomarkers of delayed graft function (DGF=dialysis requirement during the first post-transplant week) and acute rejection. STUDY DESIGN Repeated-measures prospective study. MATERIAL AND METHODS Forty consecutive adult patients with end-stage renal disease who were undergoing KTx. Leptin and adiponectin were measured in blood samples that were collected before (day-0) and after KTx (days-1, 2, 4 and 7). Linear mixed-models, receiver operating characteristic and area under curve (AUC-ROC) were used. RESULTS At post-transplant day-1, leptinemia and adiponectinemia declined 43% and 47%, respectively. At all times studied after KTx, the median leptin levels were significantly higher in patients developing DGF (n=18), but not adiponectin levels. Shortly after KTx (day-1), leptin values were significantly higher in DGF recipients in contrast to patients with promptly functioning kidneys, approximately two times higher when controlling for gender and BMI. The leptin reduction rate between pre-tranplant and one-day after KTx moderately predicted DGF (AUC=0.73). On day-1, serum leptin predicted DGF (AUC-ROC=0.76) with a performance slightly better than serum creatinine (AUC-ROC=0.72), even after correcting for BMI (AUC-ROC=0.73). Separating this analysis by gender showed that the performance of leptin in predicting DGF for male gender (AUC-ROC=0.86) improved. CONCLUSIONS Kidney graft function is an independent determinant of leptin levels, but not of adiponectin. Leptin levels at day-1 slightly outperformed serum creatinine in predicting the occurrence of DGF, and more accurately in male gender. No significant association was detected with acute rejection.

Increased urinary adenosine triphosphate in patients with bladder outlet obstruction due to benign prostate hyperplasia

Diagnosis of bladder outflow obstruction (BOO) in patients with lower urinary tract (LUT) symptoms is challenging without using invasive urodynamic tests. Recently, we showed in vitro that urothelial strips from patients with benign prostatic hyperplasia (BPH) release more ATP than controls. Here, we tested whether urinary ATP can be used as a wall tension transducer non‐invasive biomarker to detect BOO in patients with BPH.

Peritoneal phosphate removal varies by peritoneal dialysis regimen: an underestimated parameter of phosphate control

BACKGROUND The optimization of phosphate (P) removal by peritoneal dialysis (PD) is often underestimated. Our objective was to investigate peritoneal P clearance and its relationship with standard adequacy targets, hyperphosphatemia and automated PD (APD) parameters. METHODS Dialysis dose, P clearances (24-hour urine and effluent samples), estimated percentage of diffusive P removal and peritoneal transport rate (PET) were evaluated in 77 adult prevalent PD patients. RESULTS Total P removal strongly correlated with residual renal function parameters, dissociated from peritoneal Kt/V urea (r=-0.36; p=0.02) and creatinine clearance (r=-0.32; p<0.0001). A correlation of P clearance with net ultrafiltration was not found. Among the variables studied, only renal and peritoneal P clearances were significantly lower in hyperphosphatemic patients. In APD, peritoneal phosphate clearance was positively correlated with 4-hour dialysate to plasma creatinine ratio (r=0.46; p=0.039). Slow transporters had higher peritoneal P clearances under continuous ambulatory PD (CAPD) regimens. Hyperphosphatemia was significantly associated with a lower number of APD cycles and shorter nightly therapy time, with insufficient dwell time individualization. CONCLUSIONS P peritoneal clearance is a modifiable parameter of P control in PD regimens and an additional adequacy target. Prescription skills are recommended in APD patients, particularly in anurics, to take into account peritoneal transport rate.

Serum 25-hydroxyvitamin D levels in a healthy population from the North of Portugal

Vitamin D status in human populations has become a matter of great concern, in the wake of a multitude of published works that document widespread vitamin D deficiency across Europe, even in countries with abundant sunlight. In Portugal there are no measures of 25-hydroxyvitamin D - 25(OH)D - levels in the general adult population. The purpose of this study was to measure 25(OH)D levels in a healthy population cohort and investigate the possible association with season and selected demographic and laboratory measurements. A cohort of 198 participants (18-67 years) living in the north of Portugal, Porto, conducted in July and August 2015 (summer time) and April 2016 (winter time) was studied to evaluate serum 25(OH)D levels. Sociodemographic characteristics (age, sex and body mass index) and season of the year were taken into account as possible 25(OH)D levels codeterminants. In the whole group, the mean level of serum 25(OH)D was 55.4±23.4 nmol/L, with 48% of the population presenting levels compatible with vitamin D deficiency (below 50 nmol/L). In the winter period, this value reaches 74%. No statistically significant differences were observed between genders (57.4±23.9 vs. 53.3±22.8 nmol/L, p=0.219) as well as no statistically significant correlation was found between age and 25(OH)D levels (p=0.349). As expected higher levels of 25(OH)D were observed in summer than in winter (68.2±21.5 vs. 42.2±16.9 nmol/L; p<0.0001). Serum 25(OH)D levels were significantly lower in obese compared to non-obese subjects (46.6±17.6 vs. 57.7±24.2 nmol/L, p=0.012). Vitamin D deficiency is prevalent in this area, affecting almost half of the population. Body mass index and season are predictors for lower 25-hydroxyvitamin D levels and vitamin D status. An effective strategy to prevent vitamin D deficiency and insufficiency should be envisaged and implemented in our population.