Hereditary breast cancer in Middle Eastern and North African (MENA) populations: identification of novel, recurrent and founder BRCA1 mutations in the Tunisian population

Germ-line mutations in BRCA1 breast cancer susceptibility gene account for a large proportion of hereditary breast cancer families and show considerable ethnic and geographical variations. The contribution of BRCA1 mutations to hereditary breast cancer has not yet been thoroughly investigated in Middle Eastern and North African populations. In this study, 16 Tunisian high-risk breast cancer families were screened for germline mutations in the entire BRCA1 coding region and exon–intron boundaries using direct sequencing. Six families were found to carry BRCA1 mutations with a prevalence of 37.5%. Four different deleterious mutations were detected. Three truncating mutations were previously described: c.798_799delTT (916 delTT), c.3331_3334delCAAG (3450 delCAAG), c.5266dupC (5382 insC) and one splice site mutation which seems to be specific to the Tunisian population: c.212 + 2insG (IVS5 + 2insG). We also identified 15 variants of unknown clinical significance. The c.798_799delTT mutation occurred at an 18% frequency and was shared by three apparently unrelated families. Analyzing five microsatellite markers in and flanking the BRCA1 locus showed a common haplotype associated with this mutation. This suggests that the c.798_799delTT mutation is a Tunisian founder mutation. Our findings indicate that the Tunisian population has a spectrum of prevalent BRCA1 mutations, some of which appear as recurrent and founding mutations

Clinical cross-over comparison of mid-dilution hemodiafiltration using a novel dialyzer concept and post-dilution hemodiafiltration

Clinical cross-over comparison of mid-dilution hemodiafiltration using a novel dialyzer concept and post-dilution hemodiafiltration.BackgroundSeveral studies have indicated that the improved elimination of middle molecules by convective renal replacement procedures might be associated with a better outcome in end-stage renal disease (ESRD). On-line mid-dilution hemodiafiltration (HDF) with the Nephros OLpūr™ MD 190 hemodiafilter represents a novel extracorporeal renal replacement therapy concept to increase the removal of middle molecules.MethodsIn a prospective cross-over study in 10 ESRD patients, this technique was compared to on-line post-dilution HDF with a conventional synthetic high-flux dialyzer, operated at its technical limit, concerning small and middle molecular solute removal. Each patient was treated 3 times for 4.0 ± 0.4 hours with both filters. Blood flow was 400mL/min, substitution flow (QS) during mid-dilution HDF 200mL/min, and during post-dilution HDF 100mL/min, and effective dialysate flow of 700 – QSmL/min. Instantaneous clearances, reduction ratios (RR), and middle molecule mass transfer in continuously collected dialysate were determined.ResultsWhile urea and creatinine clearances were significantly lower (6.4% and 3.9%, respectively), middle molecule removal was much more efficient in mid-dilution HDF over the whole range of investigated proteins: compared to post-dilution HDF, β2-microglobulin (11.8 kD) clearance (165.8 ± 26.59 vs. 201.9 ± 20.63mL/min; P < 0.001), RR (80.0 ± 5.4% vs. 82.2 ± 5.7%; P < 0.001), and dialysate mass transfer (53% higher; P < 0.001) were significantly higher. For the larger middle molecules, cystatin C (13.4 kD) and retinol-binding protein (21.2 kD), mid-dilution HDF resulted in an even more superior performance, indicated by significantly higher values of all investigated parameters.ConclusionOn-line mid-dilution HDF with the Nephros OLpūr™ MD 190 hemodiafilter appears to be a true technologic step ahead in terms of improved middle molecule removal. This efficient procedure gives hope to play a role in preventing or at least retarding dialysis-related long-term complications, such as β2m amyloidosis, in ESRD patients, and may contribute to a more adequate dialysis therapy

MO649: Monitoring of Ionized Magnesium in Haemodialysis Patients: A Useful Tool to Allow a Personalized Prescription of Dialysate Composition

Abstract BACKGROUND AND AIMS In healthy subjects, normal values of magnesium (Mg) are in the range 0.75–0.95 mmol/L. In the circulation, 65–70% of the Mg is present in the free, ionized and dialyzable form (i.e. 0.45– 0.60 mmol/L), 20% is bound to proteins and 15% is complexed. In chronic kidney disease (CKD) dialysis patients, the dialysate Mg concentration is a major determinant of Mg balance. The aim of this study was to assess the systemic variations of ionized Mg (iMg), as well as that of ionized calcium (iCa), before and after a dialysis session. METHOD A total of 121 dialysis patients [median age = 70 (62.5–78.2) years; 74 male/46 female] in maintenance haemodialysis three times per week, for at least 6 months and with no residual function, were included. Patients were assigned to a single dialysis session with either control fluid (group 1: 3 mM acetate, 1.5 mM Ca, 0.5 mM Mg), or citrate dialysis fluid containing 0.5 mM Mg (group 2: 0.8 mM citrate, 0.3 mM acetate, 1.65 mM Ca) or 0.75 mM Mg (group 3: 0.8 mM citrate, 0.3 mM acetate, 1.65 mM Ca). Blood samples were drawn before and after the midweek dialysis sessions as part of the routine patient follow-up and quality assurance process. iMg and iCa concentrations were measured by direct ion-selective electrode on Nova Stat Profile Prime Plus® (Nova Biomedical). Total Mg (tMg) and Ca (tCa) were assessed by colorimetric method c702/Cobas 8000 analyzer (Roche). Dialytic balance was assessed by the median intra-dialytic difference between pre-dialysis and post-dialysis. RESULTS The use of all types of dialysates (whatever their composition was) was associated with a calcium load during the session (Table). In addition, an Mg loss was observed in both control and citrate dialysis fluid groups containing 0.5 mM Mg. The dialysis session induced a significant decrease in iMg (13 and 22% in group1 and group 2 respectively). By contrast, the use of citrate dialysis fluid with 0.75 mM Mg led to a positive balance with a median intra-dialytic increase of 0.08 and 0.02 mmol/L in tMg and iMg respectively (Table), corresponding to a median increase of 8 and 3% in tMg and iMg respectively. CONCLUSION The iMg fraction represents 70% of tMg in CKD stage 5D patients. While a dialysate Mg concentration at 0.5 mM leads to a negative balance, increasing the concentration to 0.75 mM significantly raises post-dialysis circulating Mg levels in these patients. Therefore, monitoring of iMg should allow a personalized prescription in dialysate Mg composition. </jats:sec

Monitoring of ionized magnesium in hemodialysis patients: A useful tool to allow a personalized prescription of dialysate composition

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Creatinine index and transthyretin as additive predictors of mortality in haemodialysis patients.: Nutritional indices of mortality in HD

BACKGROUND: Malnutrition and inflammation are recognized as important predictors of poor clinical outcome in haemodialysis (HD). This study was designed to estimate the relative contribution of known biological markers of inflammation, malnutrition and muscle mass in the prognosis of HD patients. METHODS: A total of 187 HD patients (100 women, 87 men, median age 66.7 years [22.3-93.5]) were followed-up yearly for 5 years. At baseline, pre-dialysis values of C-reactive protein (CRP), albumin, transthyretin, total HDL- and LDL-cholesterol and triacylglycerol were determined. Estimation of creatinine index (CI) as muscle mass marker was determined by creatinine kinetic modelling using pre- and post-dialysis creatinine values. RESULTS: During the follow-up period, 89 deaths (53 from cardiovascular causes) were observed. After adjustment for age, gender, dialysis vintage, smoking, diabetes mellitus and hypertension, the highest tertile of CRP and lowest tertile of transthyretin and CI were significantly associated with all-cause mortality (relative risk (RR) = 1.98 [1.12-3.47], 2.58 [1.48-4.50], 2.71 [1.42-5.19], respectively). In addition, low CI had an additive value to low levels of transthyretin. In contrast, high cholesterol (RR = 0.47 [0.27-0.83], P = 0.0091) and vitamin E concentrations (RR = 0.46 [0.26-0.80], P = 0.006) showed a protective trend for all-cause mortality. In the multivariate analysis, transthyretin appeared as the most predictive biological marker of non-CV mortality (RR = 3.78 [1.30-10.96], P = 0.014), and CI of CV mortality (RR = 2.61 [1.06-6.46], P = 0.038), respectively. Discussion. These results confirm that uraemic malnutrition constitutes an important risk factor for mortality in HD. Beyond transthyretin, CI seems to be an additional marker routinely available and monthly determined in HD patients

Creatinine index as a surrogate of lean body mass derived from urea Kt/V, pre-dialysis serum levels and anthropometric characteristics of haemodialysis patients.

BACKGROUND AND OBJECTIVES: Protein-energy wasting is common in long-term haemodialysis (HD) patients with chronic kidney disease and is associated with increased morbidity and mortality. The creatinine index (CI) is a simple and useful nutritional parameter reflecting the dietary skeletal muscle protein intake and skeletal muscle mass of the patient. Because of the complexity of creatinine kinetic modeling (CKM) to derive CI, we developed a more simplified formula to estimate CI in HD patients. DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS: A large database of 549 HD patients followed over more than 20 years including monthly CKM-derived CI values was used to develop a simple equation based on patient demographics, predialysis serum creatinine values and dialysis dose (spKt/V) using mixed regression models. RESULTS: The equation to estimate CI was developed based on age, gender, pre-dialysis serum creatinine concentrations and spKt/V urea. The equation-derived CI correlated strongly with the measured CI using CKM (correlation coefficient  = 0.79, p-value <0.001). The mean error of CI prediction using the equation was 13.47%. Preliminary examples of few typical HD patients have been used to illustrate the clinical relevance and potential usefulness of CI. CONCLUSIONS: The elementary equation used to derive CI using demographic parameters, pre-dialysis serum creatinine concentrations and dialysis dose is a simple and accurate surrogate measure for muscle mass estimation. However, the predictive value of the simplified CI assessment method on mortality deserves further evaluation in large cohorts of HD patients

Randomised trial on clinical performances and biocompatibility of four high-flux hemodialyzers in two mode treatments: hemodialysis vs post dilution hemodiafiltration

International audienceThis prospective multicenter randomized comparative cross-over trial aimed at evaluating the influence of hemodialysis vs post-dilution hemodiafiltration with high-flux dialyzers in solute clearance and biocompatibility profile. 32 patients were sequentially dialyzed with Leoceed-21HX, Polypure-22S+, Rexsys-27H and VIE-21A. Primary outcome was β2-microglobulin removal. Secondary outcomes were (i) extraction of other uremic solutes (ii) parameters of inflammation and nutrition and (iii) comparative quantification of perdialytic albumin losses (using total ‘TDC’ vs partial ‘PDC’ collection of dialysate). Significant increases in removal rates of β2-microglobulin (84.7 ± 0.8 vs 71.6 ± 0.8 mg/L), myoglobin (65.9 ± 1.3 vs 38.6 ± 1.3 µg/L), free immunoglobulin light chains Kappa (74.9 ± 0.8 vs 55.6 ± 0.8 mg/L), β-trace protein (54.8 ± 1.3 vs 26.8 ± 1.4 mg/L) and orosomucoid (11.0 ± 1.1 vs 6.0 ± 1.1 g/L) but not myostatin (14.8 ± 1.5 vs 13.0 ± 1.5 ng/mL) were observed in HDF compared to HD when pooling all dialyzers. Rexsys and VIE-A use in both HD and HDF subgroups was associated to a better removal of middle/large-size molecules compared to Leoceed and Polypure, except β2-microglobulin for Rexsys. Inflammatory parameters were unchanged between dialyzers without any interaction with dialysis modality. Mean dialysate albumin loss was comparable between TDC and PDC (1.855 vs 1.826 g/session for TDC and PDC respectively). In addition, a significant difference in albumin loss was observed between dialyzers with the highest value (4.5 g/session) observed using Rexsys. Use of all dialyzers was associated with good removals of the large spectrum of uremic toxins tested and good biocompatibility profiles, with an additional gain in removal performances with HDF. Larger surface area, thinner wall and resultant very high ultrafiltration coefficient of Rexsys should be taken into account in its clear performance advantages