Pre-treatment of dairy and breast milk with sevelamer hydrochloride and sevelamer carbonate to reduce phosphate.

INTRODUCTION: Young children and infants with chronic kidney disease are at increased risk of hyperphosphatemia because of high intake of dairy products. Hyperphosphatemia leads to metastatic calcifications and an increased risk of cardiovascular complications. Sevelamer is an effective phosphate binder, but for children it has important practical disadvantages: it clogs enteral feeding tubes and can cause gastrointestinal complaints. Pre-treatment of dairy products to reduce their phosphate content might solve those problems. METHODS: Sevelamer hydrochloride and sevelamer carbonate were suspended in various dairy products (cow's milk, breast milk, baby formula, and tube-feeding formula). Each product was tested with varying concentrations of sevelamer. After suspension, each sample was stored for 10 minutes, allowing the sevelamer to precipitate. The supernatant was decanted and analyzed for pH and for phosphate, calcium, magnesium, potassium, sodium, and chloride content. RESULTS: We observed a significant decrease in the phosphate content of all tested products. With sevelamer hydrochloride, the phosphate reduction was 48% - 91% in the various products, and with sevelamer carbonate, it was 22% - 87%. The highest effectiveness was found in breast milk. A pH increase was found in all products. With sevelamer hydrochloride, a significant increase in chloride occurred. Notably, a significant decrease in calcium content (-75%) was observed in treated breast milk. CONCLUSIONS: Pretreatment of a variety of dairy products with either sevelamer hydrochloride or sevelamer carbonate effectively reduced their phosphate content and might avoid troublesome ingestion of sevelamer in children. The change in pH with sevelamer hydrochloride was remarkable, reflecting buffering mechanisms. The reduction in the calcium content of breast milk is a potential concern and should be carefully considered and monitored during clinical use of sevelamer.

Estimated glomerular filtration rate in the nephrotic syndrome.

BACKGROUND: Plasma creatinine concentration and creatinine-based equations are most commonly used as markers of glomerular filtration rate (GFR). The abbreviated MDRD formula is considered the best available formula. Altered renal handling of creatinine, which may occur in the nephrotic syndrome, will invalidate creatinine-based formulas. We have evaluated the abbreviated MDRD formula in a large cohort of patients with proteinuria. METHODS: Data on a cohort of patients with glomerular diseases were available from a large database. We have studied the relationship between estimated GFR (MDRD formula), and plasma cystatin C (CysC) and plasma beta-2-microglobulin (ß2m) as markers of GFR. RESULTS: The final analysis included 142 patients (93 M/49 F), median age 48 years (±15), plasma creatinine 101 µmol/L (42-368), plasma albumin 28.0 g/L (10.0-47.0), proteinuria 6.4 g/day (0.03-37.9), eGFR-MDRD4 64 mL/min/1.73 m2 (15-165), ß2m 3.43 mg/L (0.7-13.8) and CysC 1.14 mg/mL (0.56-4.00). As expected, we observed a hyperbolic relationship between eGFR and both ß2m and CysC. In multivariable analysis, plasma albumin concentration proved to be the most important predictor of the relationship between eGFR and both CysC and ß2m. In the presence of hypoalbuminaemia, eGFR was ~ 30-40% higher at equal levels of plasma CysC or ß2m. Conclusions were similar when using the recently developed CKD-EPI formula. Plasma albumin concentration did not effect the relationship between eGFR estimated by the six-variable original MDRD formula and ß2m. CONCLUSIONS: Our data point to discrepancies between eGFR using the six-variable MDRD formula and eGFR using the abbreviated MDRD formula as well as the CKD-EPI formula in patients with hypoalbuminaemia. One should be aware of possible limitations of creatinine-based eGFR formulas in patients with a nephrotic syndrome.

Accuracy of bedside glucose measurement from three glucometers in critically ill patients.

OBJECTIVE: Implementation of strict glucose control in most intensive care units has resulted in increased use of point-of-care glucose devices in the intensive care unit. The aim of this study was to determine the reliability of point-of-care testing glucose meters among critically ill patients under intensive insulin treatment. DESIGN: Prospective observational study. PATIENTS: Intensive care unit and non-intensive care unit patients in a tertiary care teaching hospital. MEASUREMENTS: A glucose oxidase method was used to validate the point-of-care testing devices. Three different point-of-care testing devices, Accu-Chek Sensor (Roche Diagnostics), Precision (Abbott Diagnostics), and HemoCue were tested. Glucose measurements were performed in duplicate by an experienced technician under standardized conditions in the hospital's laboratory, using arterial (intensive care unit patients) and arterial or venous (non-intensive care unit patients) heparinized whole blood samples. MAIN RESULTS: A strong correlation was found between the glucose oxidase method and the Accu-Chek device (r = .9596, p < 0.001). Mean absolute difference between the glucose oxidase and Accu-Chek was -0.32 mmol/L (95% confidence interval -0.84 to 1.48 mmol/L). Using the International Organization for Standardization (ISO) criteria, 27 of 197 samples (13.7%) were inaccurate. In all samples that failed to meet the ISO criteria, glucose values measured by the Accu-Chek device were higher compared with the glucose oxidase method. In another set of experiments among intensive care unit patients, strong positive correlations were also found between the other point-of-care testing devices and the glucose oxidase method. However, paired samples from Accu-Chek, HemoCue, and Precision failed the ISO criteria in 9 of 82 (11.0%), 4 of 82 (4.9%), and 11 of 82 (13.4%) of cases, respectively. In non-intensive care unit patients paired samples from Accu-Chek, HemoCue, and Precision failed the ISO criteria in 3 of 120 (2.5%), 11 of 120 (9.2%), and 16 of 120 (13.3%) cases, respectively. CONCLUSIONS: Under standardized conditions, glucose results from three point-of-care testing devices were inaccurate in both intensive care unit and non-intensive care unit patients. Among intensive care unit patients, inaccurate glucose readings were most frequently falsely elevated, resulting in misinterpretation of high glucose values with subsequent inappropriate insulin administration or masking of true hypoglycemia.

Proteomic profiling and identification in peritoneal fluid of children treated by peritoneal dialysis.

BACKGROUND: Proteomic technologies offer a high-throughput analysis of the expression of proteins in biological samples. The global analysis of the proteins in peritoneal dialysis (PD) fluid will provide a better understanding of the biological processes of the peritoneal membrane. METHODS: The dialysate of nine paediatric PD patients was collected from peritoneal equilibrium tests with 3.86% glucose. Proteins were separated on a 10% SDS-PAGE gel and in-gel digested with trypsin. Peptide mixtures were analysed using nanoLC-MS/MS and results were searched against the NCBI database. RESULTS: A total number of 189 proteins were identified in the PD fluid of nine patients, with 88 proteins shared by all patients. These 88 proteins accounted for 47% of the identified proteins and >90% of the total protein content in the analysed samples. Proteins were subdivided into eight different classes according to function. CONCLUSIONS: This study gives a representative overview of the proteins present in PD fluid. The proteins in PD fluid reflect plasma proteins as well as local peritoneal processes. Potentially interesting proteins are revealed.

Biomarker discovery with SELDI-TOF MS in human urine associated with early renal injury: evaluation with computational analytical tools.

BACKGROUND: Urine proteomics is one of the key emerging technologies to discover new biomarkers for renal disease, which may be used in the early diagnosis, prognosis and treatment of patients. In the present study, we validated surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) for biomarker discovery in patients with mild ischaemic kidney injury. METHODS: We used first-morning mid-stream urine samples from healthy volunteers, and from intensive care unit patients we collected urine 12-24 h after coronary artery bypass graft (CABG) surgery. Samples of 50 volunteers were mixed to establish a reference sample (master pool). Urine samples were analysed with constant creatinine levels. RESULTS: The average intra- and interchip variation was found to be in the normal experimental range (CV of 10 to 30%). Computational analysis revealed (i) low intra-individual day-to-day variation in individual healthy volunteers; (ii) high concordance between the master pool sample and individual samples. Machine learning techniques for classification of CABG condition vs healthy patients showed that (iii) in the 3-20 kDa range, the joint activity of four protein peaks effectively discriminated the two classes, (iv) in the 20-70 kDa range, a single m/z marker was sufficient to achieve perfect separation. CONCLUSIONS: Our results substantiate the effectiveness of Seldi-TOF MS-based computational analysis as a tool for discovering potential biomarkers in urine samples associated with early renal injury.

The prognostic role of the STK15 T91A polymorphism and of STK15 mRNA expression in patients with urothelial cell carcinoma.

BACKGROUND: The prognostic role of the STK15 T91A polymorphism and of STK15 mRNA expression was investigated in patients with urothelial cell carcinoma (UCC). MATERIALS AND METHODS: The STK15 genotype with respect to the T91A polymorphism was assessed by restriction fragment length polymorphism in 135 patients. STK15 mRNA expression was measured in tumor tissues of 103 patients, using real-time quantitative PCR. RESULTS: The T91A polymorphism lacked any prognostic information in our patient cohort. Interestingly though, STK15 mRNA expression was increased in invasive and high-grade tumors (p-values of 0.009 and 0.0001, respectively). Additionally, patients with superficial UCC (n = 82) who had a tumor recurrence in the first year after surgery displayed elevated STK15 mRNA expression levels (p = 0.009). Kaplan-Meier survival analysis revealed an increased risk of tumor progression for patients with Ta tumors (n = 62) and high STK15 expression (log-rank p = 0.04). Furthermore, a decreased overall (log-rank p = 0.006) and UCC-specific survival (log-rank p = 0.001) were shown for patients with elevated STK15 mRNA levels. CONCLUSION: Patients with UCC and elevated levels of STK15 mRNA generally showed a more adverse disease course than patients with low levels. This may help in identifying patients in need of more aggressive treatment.

Simultaneous proteomic and genomic analysis of primary Ta urothelial cell carcinomas for the prediction of tumor recurrence.

BACKGROUND: The prediction of tumor recurrence in patients with Ta urothelial cell carcinoma is inaccurate and new prognostic markers are desirable. MATERIALS AND METHODS: Surface-enhanced laser-desorption ionization time-of-flight mass spectrometry (SELDI-TOF MS) was performed on 33 primary Ta tumors (16 and 17 tumors were from patients with long and short recurrence-free periods, respectively) and data were compared to previously obtained mRNA expression profiles of 49 genes. RESULTS: The intensities of a protein peak at m/z 33331 varied most significantly between the two patient groups (p = 0.0048). This was comparable to survivin, whose mRNA expression differed most significantly (p = 0.0042) of the 49 genes. ROC analysis revealed an area under the curve for protein peak 33331 and survivin of 0.78 (95% CI, 0.62-0.94) and 0.79 (95% CI, 0.63-0.94), respectively. Protein peak 33331 and survivin identified 3 (17%) and 8 (47%) patients with a recurrence-free period of at least 4 years, respectively, without generating false-negatives. CONCLUSION: These findings indicate that SELDI-TOF MS and real-time Q-PCR analysis on the same tissue can result in the identification of markers with comparable differential expression. Such combined analyses may yield combinations of several markers that might improve disease prognosis.

Gene expression analysis for the prediction of recurrence in patients with primary Ta urothelial cell carcinoma.

OBJECTIVES: The individual recurrence-free period after primary surgery of patients with Ta urothelial cell carcinoma (UCC) cannot be predicted accurately. This study aims at discriminating between patients with primary Ta UCC and long or short recurrence-free periods. METHODS: We investigated mRNA expression of 23 genes in 44 primary Ta tumours (23 and 21 tumours were from patients with long [>or=4 yr] or short [

CDC91L1 (PIG-U) mRNA expression in urothelial cell carcinomas.

CDC91L1 (PIG-U) was recently discovered as a new oncogene in human bladder cancer and showed mRNA overexpression in 36% of primary bladder tumor tissues compared to normal urothelium. We further investigated CDC91L1 mRNA expression in 8 bladder cancer cell lines, 14 normal bladder tissues and 42 urothelial cell carcinomas by real-time quantitative PCR. The prognostic value of CDC91L1 mRNA expression was also investigated. Surprisingly, only one (2.4%) tumor tissue showed overexpression compared to normal urothelium. No significant relationship of CDC91L1 mRNA expression with increasing pathologic stage (p = 0.962) or grade (p = 0.557) was observed. Median normalized CDC91L1 mRNA expression values were 0.19 for superficial tumors (n = 21) and 0.18 for invasive tumors (n = 21). Grade I, grade II and grade III tumors had median normalized expression values of 0.26, 0.18 and 0.33, respectively. CDC91L1 mRNA expression level was not indicative of early tumor recurrence (log rank p = 0.1629), tumor progression (log rank p = 0.9307) or overall and disease-specific survival (log rank p = 0.9193 and 0.4710, respectively). Our results suggest, in contrast to those of Guo et al. (Nat Med 2004;10:374-81), that the oncogene CDC91L1 is not overexpressed at the mRNA level in urothelial cell carcinomas and cannot be used to predict the course of the disease.

Exclusion of mutations in FXYD2, CLDN16 and SLC12A3 in two families with primary renal Mg2+ loss.

BACKGROUND: Based on genetic studies in families with hereditary renal Mg(2+) reabsorption disorders, several genes were shown to be involved in renal Mg(2+) transport. Mutations in the CLDN16 gene were found to underlie autosomal recessive hypomagnesaemia associated with hypercalciuria and nephrocalcinosis. The FXYD2 gene was implicated in autosomal dominant renal Mg(2+) wasting associated with hypocalciuria. Mutations in the SLC12A3 gene, also known as NCC, cause Gitelman's syndrome. In addition to hypokalaemic metabolic alkalosis, hypomagnesaemia associated with hypocalciuria is considered to be a hallmark feature of this latter disorder. METHODS: We have characterized a new family with presumed dominant renal hypomagnesaemia by detailed clinical examination and mutation analysis of CLDN16, FXYD2 and SLC12A3. In addition, we have performed mutation analysis of these three genes in a previously described family with autosomal recessive renal Mg(2+) wasting. In this family, linkage analysis was performed with polymorphic markers in the vicinity of the FXYD2 gene. RESULTS: The phenotype of the new family closely resembles that of the known dominant families with a mutation in FXYD2, but mutations in this gene were not identified in the new family. No mutations were found in CLDN16 and SLC12A3 either. Sequencing of the three genes in the patients of the recessive family revealed no mutations. In addition, haplotype analysis excluded linkage to the FXYD2 region on chromosome 11q23. CONCLUSION: Our results indicate that, in addition to the currently known loci involved in renal Mg(2+) handling, at least one other gene must be involved.