Liquid chromatography-tandem mass spectrometry method for mycophenolic acid and its glucuronide determination in saliva samples from children with nephrotic syndrome.

BACKGROUND: Saliva sampling is one of the methods of therapeutic drug monitoring for mycophenolic acid (MPA) and its metabolite, mycophenolic acid glucuronide (MPAG). The study describes the liquid chromatography tandem mass spectrometry (LC-MS/MS) method developed for saliva MPA and MPAG determination in children with nephrotic syndrome. METHODS: The mobile phase consisted of methanol and water at gradient flow, both with 0.1% formic acid. Firstly, 100 µL of saliva was evaporated at 45 °C for 2 h to dryness, secondly, it was reconstituted in the mobile phase, and finally 10 µL was injected into the LC-MS/MS system. Saliva from ten children with nephrotic syndrome treated with mycophenolate mofetil was collected with Salivette®. RESULTS: For MPA and MPAG, within the 2-500 ng/mL range, the method was selective, specific, accurate and precise within-run and between-run. No carry-over and matrix effects were observed. Stability tests showed that MPA and MPAG were stable in saliva samples if stored for 2 h at room temperature, 18 h at 4 °C, and at least 5 months at - 80 °C as well as after three freeze-thaw cycles, in a dry extract for 16 h at 4 °C, and for 8 h at 15 °C in the autosampler. The analytes were not adsorbed onto Salivette® cotton swabs. For concentrations above 500 ng/mL, the samples may be diluted twofold. In children, saliva MPA and MPAG were within the ranges of 4.6-531.8 ng/mL and 10.7-183.7 ng/mL, respectively. CONCLUSIONS: The evaluated LC-MS/MS method has met the validation requirements for saliva MPA and MPAG determination in children with nephrotic syndrome. Further studies are needed to explore plasma-saliva correlations and assess their potential contribution to MPA monitoring.

High-performance liquid chromatography with fluorescence detection for mycophenolic acid determination in saliva samples.

BACKGROUND: For therapeutic drug monitoring (TDM) of mycophenolic acid (MPA), which is frequently proposed, saliva might be a suitable and easy-to-obtain biological matrix. The study aimed to validate an HPLC method with fluorescence detection for determining mycophenolic acid in saliva (sMPA) in children with nephrotic syndrome. METHODS: The mobile phase was composed of methanol and tetrabutylammonium bromide with disodium hydrogen phosphate (pH 8.5) at a 48:52 ratio. To prepare the saliva samples, 100 µL of saliva, 50 µL of calibration standards, and 50 µL of levofloxacin (used as an internal standard) were mixed and evaporated to dryness at 45 °C for 2 h. The resulting dry extract was reconstituted in the mobile phase and injected into the HPLC system after centrifugation. Saliva samples from study participants were collected using Salivette® devices. RESULTS: The method was linear within the range of 5-2000 ng/mL, was selective with no carry-over effect and met the acceptance criteria for within-run and between-run accuracy and precision. Saliva samples can be stored for up to 2 h at room temperature, for up to 4 h at 4 °C, and for up to 6 months at - 80 °C. MPA was stable in saliva after three freeze-thaw cycles, in dry extract for 20 h at 4 °C, and for 4 h in the autosampler at room temperature. MPA recovery from Salivette® cotton swabs was within the range of 94-105%. The sMPA concentrations in the two children with nephrotic syndrome who were treated with mycophenolate mofetil were within 5-112 ng/mL. CONCLUSIONS: The sMPA determination method is specific, selective, and meets the validation requirements for analytic methods. It may be used in children with nephrotic syndrome; however further studies are required to investigate focusing on sMPA and the correlation between sMPA and total MPA and its possible contribution to MPA TDM is required.

Limited sampling strategy to predict free mycophenolic acid area under the concentration-time curve in paediatric patients with nephrotic syndrome.

In paediatric patients, there is no data on the recommended area under the concentration-time curve from 0 to 12 h (AUC0-12 ) for free mycophenolic acid (fMPA), which is the active form of the drug, responsible for the pharmacological effect. We decided to establish the limited sampling strategy (LSS) for fMPA for its use in MPA therapeutic monitoring in children with nephrotic syndrome treated with mycophenolate mofetil (MMF). This study included 23 children (aged 11 ± 4 years) from whom eight blood samples were collected within 12 h after MMF administration. The fMPA was determined using the high-performance liquid chromatography with fluorescence detection method. LSSs were estimated with the use of R software and bootstrap procedure. The best model was chosen based on a number of profiles with AUC predicted within ± 20% of AUC0-12 (good guess), r2 , mean prediction error (%MPE) of ±10% and mean absolute error (%MAE) of less than 25%. The fMPA AUC0-12 was 0.1669 ± 0.0697 µg h/mL and the free fraction was within 0.16%-0.81%. In total, there were 92 equations developed of which five fulfilled the acceptance criteria for %MPE, %MAE, good guess >80% and r2 > 0.900. These equations consisted of three time points: model 1 (C1 , C2 , C6 ), model 2 (C1 , C3 , C6 ), model 3 (C1 , C4 , C6 ), model 5 (C0 , C1 , C2 ), and model 6 (C1 , C2 , C9 ). Although blood sampling up to 9 h after MMF dosing is impractical, it is crucial to include C6 or C9 in LSS to assess fMPA AUCpred correctly. The most practical fMPA LSS, which fulfilled the acceptance criteria in the estimation group, was fMPA AUCpred  = 0.040 + 2.220 × C0 + 1.130 × C1 + 1.742 × C2 . Further studies should define the recommended fMPA AUC0-12 value in children with nephrotic syndrome.

Acute kidney injury and diabetic kidney disease in children with acute complications of diabetes.

BACKGROUND: Diabetic ketoacidosis (DKA) and hyperglycaemia without ketoacidosis are common acute complications of diabetes. Their association with acute kidney injury (AKI) and diabetic kidney disease (DKD) was studied. METHODS: The study group consisted of 197 children with type 1 diabetes with average diabetes duration of 8.08 ± 2.32 years. The medical history of the patients was retrospectively reviewed. The number of children with severe hyperglycaemia, DKA and AKI was assessed. The association with the risk of chronic kidney disease (CKD) was analysed. RESULTS: AKI was found in 14% of cases hospitalised for DKA and 8% of cases hospitalised for hyperglycaemia. Patients with AKI showed a significantly increased corrected sodium (141.23 ± 5.09 mmol/L, p = 0.035). Patients with AKI in DKA showed a significant increase in WBC (20.73 ± 8.71 × 103/µL, p = 0.0009). Follow-up analysis after a minimum of 5 years of diabetes revealed that a single episode of DKA was found in 63 patients and a single episode of AKI in 18 patients. Two or more episodes of DKA were found in 18 patients, and nine cases were complicated by AKI. These patients showed a significant increase in urinary albumin excretion (44.20 ± 64.21 mg/24 h), the highest values of eGFR and the worst glycaemic control. CONCLUSIONS: Diabetic children can develop AKI in the course of DKA and hyperglycaemia without ketoacidosis, which is associated with volume depletion and reflected by corrected sodium concentration. AKI in DKA seems to be complicated by stress and inflammation activation. AKI and poor glycaemic control with repeated DKA episodes can magnify the risk of progression to DKD. A higher resolution version of the Graphical abstract is available as Supplementary information.

Inosine monophosphate dehydrogenase activity and mycophenolate pharmacokinetics in children with nephrotic syndrome treated with mycophenolate mofetil.

Some studies have shown that the area under the concentration-time curve (AUC) of mycophenolic acid (MPA) should be higher for children with nephrotic syndrome (NS) than after renal transplantation. The pharmacodynamic aspect of MPA, the activity of inosine monophosphate dehydrogenase (IMPDH), has not been studied in children with NS. The study included 21 children (4-16 years old) with NS treated with mycophenolate mofetil. MPA and its glucuronide plasma concentrations were determined using validated high-performance liquid chromatography-ultraviolet (HPLC-UV). The separate HPLC-UV method was applied for IMPDH activity determination. The variability was expressed by the coefficient of variation (CV). IMPDH activity and MPA concentration (Ctrough ) before the morning dose amounted to 29.95 µmol s-1  mol-1 adenosine monophosphate (AMP) (range, 6.71-98.60 µmol s-1  mol-1 AMP) and 1.72 µg/mL (range, 0.39-4.34 µg/mL), respectively, whereas the area under the effect-time curve from 0 to 4 h and MPA AUC0-4 were 130.36 µmol s-1  mol-1 AMP × h (range, 23.58-306.57 µmol s-1  mol-1 AMP × h) and 24.63 µg h/mL (range, 12.21-67.48 µg h/mL), respectively. IMPDH activity decreased concomitantly with MPA concentration increase, however, the variability of the pharmacodynamic parameters was greater than of the pharmacokinetics. The median degree of maximum IMPDH inhibition was 61%. MPA Ctrough and predicted AUC were lower than in our previous study. Only a few MPA pharmacokinetic parameters correlated with the pharmacodynamics. IMPDH activity did not correlate with the children's age and did not differ between boys and girls. MPA clearance was the highest in younger children (median, 10.54 L/m2 /h) and cholesterol correlated negatively with the children's age (r = -0.659, P = 0.003). IMPDH minimum activity and the degree of maximum IMPDH inhibition were similar to those obtained in renal transplant recipients. IMPDH activity does not undergo developmental or gender-specific regulation in children with NS. MPA underexposure might be more frequent in younger children, especially with high cholesterol and triglycerides levels because of high MPA clearance.

Chronic kidney disease predictors in obese adolescents.

BACKGROUND: Glomerular hyperfiltration, initiating development of obesity-related glomerulopathy, results in an enlargement of the glomeruli and unsealing of the filtration barrier. It can be followed by adaptive focal segmental glomerulosclerosis and chronic kidney disease (CKD). The aim of the study was to determine the expression pattern of lipid metabolism and selected kidney damage markers in obese adolescents and to identify potential factors which can predict CKD. METHODS: The study group consisted of 142 adolescents with a BMI z-score > 2. Sixty-two healthy and normal-weight individuals served as controls. The factors associated with the rate of glomerular filtration in obese adolescents were assessed by linear regression methods using univariate and multivariate analyses. The risk of developing CKD was estimated using the Fisher's exact test. RESULTS: The study group was divided into "elevated," "normal," and "decreased" glomerular filtration rate (GFR) patients. Increased urine galectin-3 (Gal-3) concentration was diagnosed in all patients. "Decreased GFR" subjects expressed increased urine concentration of neutrophil gelatinase-associated lipocalin (NGAL) and daily megalin excretion. Thirty-nine study participants developed CKD. Increased uric acid (UA) concentration was associated with CKD development both in "normal" and "decreased GFR" patients. Additionally, in "normal" GFR patients, increased concentrations of cholesterol (Ch), triglycerides (TG), and NGAL were associated with CKD. CONCLUSIONS: Increased serum concentrations of Ch, TG, and UA and increased urine concentration of NGAL might predict CKD development in obese adolescents with normal and decreased GFR. A higher resolution version of the Graphical abstract is available as Supplementary information.

Relationship between Gd-IgA1 and TNFR1 in IgA nephropathy and IgA vasculitis nephritis in children - multicenter study.

AIM OF THE STUDY: To evaluate the relationship between serum Gd-IgA1 (sGd-IgA1) and serum and urine TNFR1 (sTNFR1, uTNFR1) levels as possible prognostic factors in IgA nephropathy (IgAN) and IgA vasculitis nephritis (IgAVN). MATERIAL AND METHODS: From 299 patients from the Polish Registry of Pediatric IgAN and IgAVN, 60 children (24 IgAN and 36 IgAVN) were included in the study. The control group consisted of 20 healthy children. Proteinuria, haematuria, serum creatinine as well as IgA and C3 levels were measured and glomerular filtration rate (GFR) was calculated at onset and at the end of the follow-up. Kidney biopsy findings were evaluated using the Oxford classification. Serum Gd-IgA1 and serum and urine TNFR1 levels were measured at the end of follow-up. RESULTS: Serum Gd-IgA1 level was significantly higher in IgAN and IgAVN patients in comparison to the control group. Urine TNFR1 was significantly higher in IgAN than in IgAVN and the control group. We did not observe any differences in sTNFR1 level between IgAN, IgAVN and control groups. We found a positive correlation between Gd-IgA1 and creatinine (r = 0.34), and negative between Gd-IgA1 and GFR (r = -0.35) at the end of follow-up. We observed a negative correlation between uTNFR1/creatinine log and albumin level and protein/creatinine ratio. We did not find any correlations between Gd-IgA1 and TNFR1. CONCLUSIONS: The prognostic value of sGd-IgA1 in children with IgAN and IgAVN has been confirmed. TNFR1 is not associated with Gd-IgA1 and is not a useful prognostic marker in children with IgAN/IgAVN and normal kidney function.

The Role of Complement Component C3 Activation in the Clinical Presentation and Prognosis of IgA Nephropathy-A National Study in Children.

The aim of the study was to evaluate the influence of the intensity of mesangial C3 deposits in kidney biopsy and the serum C3 level on the clinical course and outcomes of IgAN in children. The study included 148 children from the Polish Pediatric IgAN Registry, diagnosed based on kidney biopsy. Proteinuria, creatinine, IgA, C3 were evaluated twice in the study group, at baseline and the end of follow-up. Kidney biopsy was categorized using the Oxford classification, with a calculation of the MEST-C score. The intensity of IgA and C3 deposits were rated from 0 to +4 in immunofluorescence microscopy. The intensity of mesangial C3 > +1 deposits in kidney biopsy has an effect on renal survival with normal GFR in children with IgAN. A reduced serum C3 level has not been a prognostic factor in children but perhaps this finding should be confirmed in a larger group of children.

Differences between Obese and Non-Obese Children and Adolescents Regarding Their Oral Status and Blood Markers of Kidney Diseases.

(1) Background: A rarely discussed effect of obesity-related glomerulopathy (ORG) may slowly lead to irreversible glomerular damage and the development of chronic kidney disease. These patients need to undertake medical care, but whether they should be included in intensive oral care is still not mandatory. The study aimed to assess a relationship between renal, metabolic, and oral health indicators among pediatric patients affected by simple obesity. (2) Methods: 45 children and adolescents with simple obesity hospitalized (BMI 34.1 ± 4.8 kg/m2, age 15.4 ± 2.3) and compared with 41 aged-matched healthy controls (BMI 16.4 ± 2.4 kg/m2, age 15.4 ± 2.7). Echocardiography, 24-h ambulatory blood pressure monitoring, ultrasound exam with Doppler, and laboratory tests including kidney and metabolic markers were performed. Oral status was examined regarding the occurrence of carious lesions using decay missing filling teeth (DMFT), gingivitis as bleeding on probing (BOP), and bacterial colonization as plaque control record (PCR). (3) Results: The strongest correlation was revealed between BMI and concentration of uric acid, cystatin C, GFR estimated by the Filler formula (r = 0.74; r = 0.48; r = -0.52), and between oral variables such as PCR and BOP (r = 0.54; r = 0.58). Children and adolescents with obesity demonstrated untreated dental caries, less efficient in plaque control and gingivitis. (4) Conclusions: No specific relation to markers of kidney disease were found; however, more frequent gingivitis/bacterial colonization and significant differences in oral status between obese and non-obese patients were revealed. Susceptibility to inflammation may be conducive to developing metabolic syndrome and kidney damage in the form of obesity-related glomerulopathy and contribute to future dental caries. Uric acid seems to indicate metabolic syndrome and cardiovascular complications (LVMI > 95 percentiles). Cystatin C and uric acid might aspire to be early markers of kidney damage leading to obesity-related glomerulopathy.

The Evaluation of Multiple Linear Regression-Based Limited Sampling Strategies for Mycophenolic Acid in Children with Nephrotic Syndrome.

We evaluated mycophenolic acid (MPA) limited sampling strategies (LSSs) established using multiple linear regression (MLR) in children with nephrotic syndrome treated with mycophenolate mofetil (MMF). MLR-LSS is an easy-to-determine approach of therapeutic drug monitoring (TDM). We assessed the practicability of different LSSs for the estimation of MPA exposure as well as the optimal time points for MPA TDM. The literature search returned 29 studies dated 1998-2020. We applied 53 LSSs (n = 48 for MPA, n = 5 for free MPA [fMPA]) to predict the area under the time-concentration curve (AUCpred) in 24 children with nephrotic syndrome, for whom we previously determined MPA and fMPA concentrations, and compare the results with the determined AUC (AUCtotal). Nine equations met the requirements for bias and precision ±15%. The MPA AUC in children with nephrotic syndrome was predicted the best by four time-point LSSs developed for renal transplant recipients. Out of five LSSs evaluated for fMPA, none fulfilled the ±15% criteria for bias and precision probably due to very high percentage of bound MPA (99.64%). MPA LSS for children with nephrotic syndrome should include blood samples collected 1 h, 2 h and near the second MPA maximum concentration. MPA concentrations determined with the high performance liquid chromatography after multiplying by 1.175 may be used in LSSs based on MPA concentrations determined with the immunoassay technique. MPA LSS may facilitate TDM in the case of MMF, however, more studies on fMPA LSS are required for children with nephrotic syndrome.

Prediction of steroid resistance and steroid dependence in nephrotic syndrome children.

BACKGROUND: Steroid resistant (SR) nephrotic syndrome (NS) affects up to 30% of children and is responsible for fast progression to end stage renal disease. Currently there is no early prognostic marker of SR and studied candidate variants and parameters differ highly between distinct ethnic cohorts. METHODS: Here, we analyzed 11polymorphic variants, 6 mutations, SOCS3 promoter methylation and biochemical parameters as prognostic markers in a group of 124 Polish NS children (53 steroid resistant, 71 steroid sensitive including 31 steroid dependent) and 55 controls. We used single marker and multiple logistic regression analysis, accompanied by prediction modeling using neural network approach. RESULTS: We achieved 92% (AUC = 0.778) SR prediction for binomial and 63% for multinomial calculations, with the strongest predictors ABCB1 rs1922240, rs1045642 and rs2235048, CD73 rs9444348 and rs4431401, serum creatinine and unmethylated SOCS3 promoter region. Next, we achieved 80% (AUC = 0.720) in binomial and 63% in multinomial prediction of SD, with the strongest predictors ABCB1 rs1045642 and rs2235048. Haplotype analysis revealed CD73_AG to be associated with SR while ABCB1_AGT was associated with SR, SD and membranoproliferative pattern of kidney injury regardless the steroid response. CONCLUSIONS: We achieved prediction of steroid resistance and, as a novelty, steroid dependence, based on early markers in NS children. Such predictions, prior to drug administration, could facilitate decision on a proper treatment and avoid diverse effects of high steroid doses.

Dental caries-related primary hypertension in children and adolescents: Cross-sectional study.

BACKGROUND: Hypertension is a growing clinical problem in pediatric population. Also, the cause of hypertension is usually unknown and it may result from systemic inflammation related to tooth decay. AIM: To estimate the potential association in cross-sectional study between tooth decay and hypertension in children and adolescents. PATIENTS AND METHODS: Study group-65 children diagnosed with primary arterial hypertension; control subjects-44 normotensive children. Blood pressure, dental examination, measurement of salivary cortisol, alpha-amylase, secretory IgA, and lysozyme concentrations were performed in all of the children. RESULTS: Hyper- and normotensive children had similar peripheral blood morphology and serum biochemical parameters, except of uric acid concentration, which was significantly higher in the study group (p = .047). Salivary evening concentrations of cortisol and alpha-amylase were significantly higher in hypertensive children (p = .002 and p = .004, respectively). Although 24-hr systolic blood pressure (SBP), including daytime and nighttime SBP, correlated with "decay," "microalbuminuria," "BMI," and "glomerular filtration rate" (r > .75, r > .7, r < .68, and r < .43, respectively), in multivariate analysis only "decay" was associated with hypertension both in children and in adolescents (p < .0001). CONCLUSION: Tooth decay in children/adolescents might be regarded as a potent trigger factor of hypertension in individuals in whom all other causes of secondary arterial hypertension have been excluded.

Association of Oral Status and Early Primary Hypertension Biomarkers among Children and Adolescents.

The aim of this case-control study was the evaluation of the association between biomarkers of early primary arterial hypertension (HA) and oral diseases among children and adolescents. Material and methods. Subjects suspected of primary HA (n = 180) underwent a complex evaluation of their vascular status: blood pressure, heart rate, vascular stiffness, sympathetic activity in a 24 h ambulatory examination, followed by measurement of serum uric acid (UA), cystatin C, and creatinine. This procedure allowed the identification of children with primary (n = 58) and secondary HA (n = 74), as well as of children with normal arterial blood pressure, who served as a control group (n = 48). All subjects with secondary HA were excluded from further investigation. Oral examination included the measurement of caries intensity (using the decayed, missing, filled index for permanent teeth DMFT /primary teeth dmft), bacterial plaque (by the plaque control record index, PCR%), and gingivitis (by the bleeding on probing index, BOP%). For statistical analysis, a linear regression model and Spearman rank correlation were used. Results. UA, cystatin C, and creatinine were not altered in the HA group. However, the number of decayed permanent teeth (DT) and the DMFT, PCR%, and BOP% indexes were significantly higher in the primary HA group compared to the control group (p = 0.0006; p = 0.02; p = 0.0009; p = 0.003). Our results are not sufficient to prove the important role of caries and gingival inflammation in the modulation of HA symptoms, although they prove the association of oral diseases with primary HA symptoms. This may indicate future strategies for preventive measures for hypertensive children and adolescents.

The Application of Inosine 5'-Monophosphate Dehydrogenase Activity Determination in Peripheral Blood Mononuclear Cells for Monitoring Mycophenolate Mofetil Therapy in Children with Nephrotic Syndrome.

In pediatric nephrotic syndrome, recommended mycophenolic acid (MPA) pharmacokinetics are higher than those for transplant recipients. In MPA therapeutic monitoring, inosine-5'-monophosphate dehydrogenase (IMPDH) activity may be useful. We modified the method established for renal transplant recipients and determined IMPDH activity in peripheral blood mononuclear cells (PBMCs) from healthy volunteers and children (4-16 years) with nephrotic syndrome treated with mycophenolate mofetil (MMF). From children, four blood samples were collected, and MPA concentrations were also determined. IMPDH activity was calculated using xanthosine monophosphate (XMP) normalized with adenosine monophosphate (AMP), both determined with the HPLC-UV method. The modified method was accurate, precise, and linear for AMP and XMP within 0.50-50.0 µmoL/L. Mean IMPDH activity in volunteers was 45.97 ± 6.24 µmoL·s-1·moL-1 AMP, whereas for children, the values were variable and amounted to 39.23 ± 27.40 µmoL·s-1·moL-1 AMP and 17.97 ± 15.24 µmoL·s-1·moL-1 AMP before the next MMF dose and 1 h afterward, respectively. The modified method may be applied to IMPDH activity determination in children with nephrotic syndrome treated with MMF. IMPDH activity should be determined after one thawing of PBMCs due to the change in AMP and XMP concentrations after subsequent thawing. For children, the lowest IMPDH activity was observed concomitantly with the highest MPA concentration.

Early kidney damage in diabetic adolescents with increased blood pressure and glomerular hyperfiltration.

BACKGROUND: The early impact of type-1 diabetes mellitus (DM1), increased blood pressure and glomerular hyperfiltration (GHF) on kidney damage in adolescents using two urinary markers of kidney injury - neutrophil gelatinase-associated lipocalin (uNGAL) and transferrin (uTransf) was assessed. METHODS: The study group consisted of 80 adolescents with DM1, of whom 42 were patients with increased blood pressure (IBP), and 38 were patients with normal blood pressure (NBP). Blood pressure was assessed by 24-hour ambulatory bloodpressure monitoring. All patients showed estimated glomerular-filtration rates (eGFRs) above 90 ml/min/1.73m2. The control group consisted of 19 healthy, age and gender-matched adolescents. RESULTS: All diabetic children showed a significant increase in uNGAL (p<0.001). This increase was not related to blood pressure. The uNGAL was elevated in all patients with normal albuminuria, normal eGFR and NBP. The concentration of uTransf was not increased in the entire studied group and was not related to blood pressure. Children with GHF had significantly higher levels of both uTransf (p=0.010) and uNGAL (p<0.001). In patients with GHF, blood pressure was normal. Patients with IBP showed a significantly higher value for triglycerides (r=0.247; p=0.032) and a longer duration of diabetes (r=0.264; p=0.019). CONCLUSIONS: Diabetes is the leading risk factor for early kidney injury. However, increased blood pressure does not lead to kidney damage, at least in the early stage of DM1. The uNGAL is the early indicator of kidney injury and increases in patients with normal albuminuria, normal glomerular filtration and normal blood pressure. Glomerular hyperfiltration seems to be a marker of diabetic-kidney involvement.

Comparison of cuff-based and cuffless continuous blood pressure measurements in children and adolescents.

OBJECTIVE: In recent times, new methods of blood pressure measurements have been introduced, including cuffless blood pressure (BP) measurement device using pulse transit time (PTT) for calculation of BP values. However, it is still unknown how values obtained with a new cuffless device compare with standard ambulatory measurements in children. The main aim of the study was to investigate whether BP values measured by a cuffless PTT device are comparable with measurements by a standard upper arm cuff-based BP device. METHODS: Thirty children were prospectively included. Blood pressure measurements using the cuffless device (Somnotouch-NIBP) and cuff-based standard device (Omron 907) were performed simultaneously on the left and right arm. RESULTS: Mean systolic BP of the standard measurements was 123,47 ± 14,91 mmHg and 127,48 ± 15,98 mmHg (p < .001) measured by cuffless method. Mean diastolic BP of the standard ABPM measurements was 66,88 ± 11,86 mmHg and 68,52 ± 12,36 mmHg (p < .001). There were significant positive correlations between standard and cuffless measurements. CONCLUSION: The results show that the created PWV-BP function produces a significant correlation between BP derived from the PWV and the SBP measured by sphygmomanometry. When applying this device in clinical practice, one may keep in mind that the reported mean values over 24 hours, awake and asleep time are not directly interchangeable with cuff-based standard 24-hour BP values. The measured BP values were higher by the new technique. Although differences in SBP between both methods reached values up to 20 mmHg, we think that the development of a cuffless BP monitoring system will provide novel solutions in various medical situations.

Limited sampling strategy to predict mycophenolic acid area under the curve in pediatric patients with nephrotic syndrome: a retrospective cohort study.

PURPOSE: Limited sampling strategy (LSS) is a precise and relatively convenient therapeutic drug monitoring method. We evaluated LSSs for mycophenolic acid (MPA) in children with nephrotic syndrome treated with mycophenolic mofetil (MMF) and validated the LSSs using two different approaches. METHODS: We measured MPA plasma concentrations in 31 children using HPLC-UV method and received 37 MPA pharmacokinetic profiles (0-12 h). For six children, MPA profiles were estimated twice after two MMF doses. LSSs were developed using multilinear regression with STATISTICA and R software and validated using validation group and bootstrap method, respectively. RESULTS: The best three time point equations included C1, C3, C6 (good guess 83%, bias - 2.78%; 95% confidence interval (CI) - 9.85-0.46); C1, C2, C6 (good guess 72%, bias 0.72%; 95% CI - 5.33-7.69); and C1, C2, C4 (good guess 72%, bias 2.05%; 95% CI - 4.92-13.01) for STATISTICA software. For R software, the best equations consisted of C1, C3, C6 (good guess 92%, bias - 2.69%; 95% CI - 27.18-33.75); C0, C1, C3 (good guess 84%, bias - 2.11%; 95% CI - 24.19-22.29); and C0, C1, C2 (good guess 84%, bias - 0.48%; 95% CI - 30.77-54.07). During validation, better results were obtained for R evaluations, i.e., bootstrap method. CONCLUSIONS: The most useful equations included C0, C1, C3 and C0, C1, C2 time points; however, the most precise included C1, C3, C6 time points because of MPA enterohepatic recirculation. Better results were obtained for bootstrap validation due to greater number of patients. Validated LSS should be used only in the population for which it was developed. As there is growing evidence that underexposure of MPA is associated with insufficient treatment response, we recommend the introduction of therapeutic drug monitoring for MPA in children with nephrotic syndrome.

Multicenter analysis of the efficacy and safety of a non-standard immunosuppressive therapy with rituximab in children with steroid-resistant nephrotic syndrome.

The aim of the study was a multicenter analysis of the efficacy and safety of a non-standard immunosuppressive therapy with rituximab (Rtx) in children with steroid-resistant nephrotic syndrome (SRNS) with particular emphasis on the possibility of permanent discontinuation or dose reduction of other immunosuppressive drugs such as glucocorticoids and cyclosporine A after 6 months of observation. The study group consisted of 30 children with idiopathic nephrotic syndrome, who were unresponsive to standard immunosuppressive treatment, and hospitalized in the years 2010-2017 in eight paediatric nephrology centres in Poland. The children were administered a single initial infusion of rituximab at the dose of 375 mg/m2 of the body surface area. Proteinuria, the daily supply of glucocorticoids, and cyclosporine were assessed at the moment of the start of the treatment and after 6 months since its commencement. Before Rtx therapy, complete remission was found in 13 patients (43%) and partial remission was found in 8 patients (26%). These numbers increased to 16 (53%) and 12 (40%), respectively. At the start of the treatment 23 patients (76.6%) were treated with cyclosporine A. After 6 months, this number decreased to 15 patients (35%). At the start of the treatment, 18 patients (60%) were treated with prednisone. After 6 months, this number decreased to 8 patients (44%). Children with SRNS may potentially benefit from Rtx treatment despite relative risk of side effects. The benefits may include reduction of proteinuria or reduction of other immunosuppressants.

Circulating suPAR as a biomarker of disease severity in children with proteinuric glomerulonephritis.

BACKGROUND: The increase of circulating urokinase plasminogen activator receptor (suPAR) was demonstrated in various diseases showing its prognostic value as well as the link to the inflammatory reaction. In glomerular diseases, suPAR was considered a causative factor of proteinuria. In the present study we aimed to evaluate serum concentration of suPAR in children with primary and secondary glomerulonephritis (GN) and its association with disease severity. METHODS: The study involved 22 children with minimal change disease (MCD), nine with primary focal segmental glomerulosclerosis (FSGS), seven with Henoch-Schönlein nephritis, seven with lupus nephritis (LN) and 16 controls. RESULTS: Serum suPAR was significantly higher in children with FSGS and LN than controls (4.47±1.39 ng/mL vs. 3.23±0.76 ng/mL; P=0.011 and 6.17±1.12 ng/mL vs. 3.23±0.76 ng/mL, respectively; P<0.0001). Further, suPAR was increased in LN when compared to FSGS (P=0.031). In the total group suPAR showed negative correlation with eGFR, serum complement C3 and positive with left ventricular mass index. In children with MCD and FSGS the inverse association of suPAR with eGFR was also shown. CONCLUSIONS: In children with primary and secondary glomerulonephritis suPAR levels are not associated with proteinuria. In primary GN elevated suPAR levels may result from reduced eGFR reflecting renal damage. In LN circulating suPAR can be increased further indicating both multi-organ involvement and systemic inflammation reflecting disease severity.

Antihypertensive treatment prescription in pediatric dialysis patients in Poland: A comparison between two nationwide studies 2003/2004-2013.

BACKGROUND: Blood pressure in pediatric dialyzed patients is under poor control. OBJECTIVES: The aim of the study was to assess the strategy and efficacy of antihypertensive drugs used for the treatment of hypertension in pediatric dialyzed patients in 2013 in comparison with the data collected in 2003/2004. The results have been viewed against present strategies of antihypertensive treatment in children. There is still limited data concerning the treatment of hypertension in dialyzed pediatric patients. MATERIAL AND METHODS: The study embraced 10 of 12 pediatric dialysis units in Poland treating 59 pediatric patients (mean age - 132 months). Collected information included present antihypertensive treatment with regard to drug classes and the dose of antihypertensive agent. The treatment was regarded as effective if both systolic and diastolic values of blood pressure were below 1.64 SDS. The results from 2013 were juxtaposed with previously analyzed data from a similar study on hypertension in dialyzed children conducted in 2003/2004. RESULTS: Forty subjects have been provided with antihypertensive treatment. In monotherapy and polytherapy 50% of the subjects were treated with ACEI (enalapril and ramipril), 67.5% with amlodipine, 50% with beta-blockers. Only 10% of the subjects were treated with angiotensin II receptor blocker (losartan). Thirty percent of the subjects received furosemide, whereas 5% were given doxazosin. Antihypertensive drugs regarded as the 2nd and 3rd choice in treating high blood pressure (doxazosin, beta-blockers and furosemide) were applied as monotherapy in 46% of the patients. Satisfactory control of treated blood pressure was reached in 45% of them. CONCLUSIONS: Antihypertensive treatment in dialyzed children did not change significantly during the last decade with regard to the groups of drugs being used. Despite a wider feasibility of antihypertensive substances, the effectiveness of this therapy was still unsatisfactory.