Individualized Neoral doses in pediatric renal transplantation

We propose a model to calculate individualized Neoral doses based on individual oral clearance (CL/F)(i) and AUC((0-12h)) values. The equation proposed by Dr. Ke-Hua Wu (2005), was employed to calculate the CL/F(i) = 28,5 - (1.24*POD) - 0.252*(TBil-11) + 0,188*(Weight o-58) -0,191*(Age-42) - 2,42*INHI - 0,212*(HCT-28), where CI/F = (L/h), POD = postoperative days, Bil.T = total bilirubin level (umol/L), CBW = in kilograms, age = in years, INHI = concurrent metabolic inhibitors present (1) or absence (0), and HCT = hematocrit percentage. The AUC((0-12h)) was calculated from the C(2) value using the equation AUC((0-12h)) = 815,578 + 4,44696*C(2), derived from the linear correlation observed in earlier work at Clinica Las Condes Hospital. The studied population were 30 kidney transplanted children at Luis Calvo Mackenna Hospital, between 2002 and 2006, who were divided into 2 similar groups according to accurate C(2) sampling time collections. The control group 1 was composed of 13 patients of age 9.85 +/- 4 years whose samples were collected correctly. Group 2 was composed of 17 patients of age 10.43 +/- 6 years with 252 C(2) samples, which were obtained at medical control. All patients were under oral treatment with prednisone, azathioprine, nifedipine, and Neoral administered twice day according the weight of the patient and the C(2) level. Relating Neoral administered doses to calculated doses according to the proposed model, the control group showed a linear correlation coefficient r = 0.924; r(2) = 85.4%; (P < .05), and group 2, r = 0.54; r(2) = 29.1 (P < .05). The proposed model to calculate Neoral doses had a predictive value of 85.0% when C(2) samples were collected correctly.

Phenotypic, serological and genetic characterization of Flavobacterium psychrophilum strains isolated from salmonids in Chile

Characterization of 20 Flavobacterium psychrophilum strains isolated from farmed Atlantic salmon and rainbow trout in Chile was done using phenotypic, antigenic and genetic techniques. Experimental infections were also performed to assess the virulence of two representative isolates and of the type strain. Biochemical and physiological analyses showed that Chilean F. psychrophilum strains, regardless of the host species, constitute a phenotypically very homogeneous group matching with previous descriptions of this pathogen. However, serological assays indicated the existence of antigenic heterogeneity with four patterns of serological reactions. The first group contained most (14 of 20) of the F. psychrophilum isolates showing cross-reaction with the antisera obtained against Atlantic salmon and rainbow trout isolates. Group 2 corresponded to four other rainbow trout isolates (1658, 1731, 1762 and 29009) that did not agglutinate with anti-1150 serum. Two minor serological groups were identified for the remaining isolates (Groups 3 and 4). Marked homogeneity was also revealed by genetic studies including 16S rRNA alleles, random amplified polymorphic DNA and REP-PCR showing that a major genetic group of F. psychrophilum may be dominant in disease outbreaks in farms. Restriction fragment length polymorphism of PCR analysis showed that gyrase genotypes B-S or B-R were found in Chilean isolates from rainbow trout and Atlantic salmon, whereas genotype A was not found. Virulence assays using Atlantic salmon indicated no relationship between the degree of pathogenicity and the host origin of the F. psychrophilum strains.

Comparison of Cyclosporine Concentrations 2 Hours Post-Dose Determined Using 3 Different Methods and Trough Level in Pediatric Renal Transplantation

Immunosuppression has been one of the great challenges in pediatric recipients of kidney allografts. Cyclosporine (CsA) has evolved during the past 25 years of transplantation. It requires frequent blood level monitoring because of its narrow therapeutic window and interpatient and intrapatient variability. Neoral (Novartis) is no exception. Ideally, monitoring of blood levels should also include determination of the area under the time-concentration curve (AUC) to better target the therapeutic window, thus avoiding underdosing or overdosing, especially in pediatric patients. A single blood concentration measurement 2 hours after Neoral administration (C2) has been shown to be a more for accurate predictor of drug exposure than trough levels (C0). Therefore, its use may lead to reduction in the incidence and severity of cellular rejection and of CsA toxicity. Some studies have shown that the metabolites/CsA ratio is substantially lower using C2 than C0, however, the between-assay differences for C2 monitoring have not been considered. The purpose of this study was to evaluate CsA C0 and C2 levels, determined using monoclonal fluorescence polarization immunoassay (FPIA)/TDx and enzyme multiplied immunoassay (EMIT). CsA levels were determined using a radioimmunoassay (RIA) in 30 pediatric transplant recipients with stable renal function within 42.7 mean months follow-up. Mean age was 13.4 years; 15 children were girls; 23 patients were recipients of cadaveric kidneys. The mean CsA microemulsion dose was 5.7 mg/kg/d. The 3 methods showed a high correlation between C0 and C2 (r > or = 0.97). A linear regression slope was significantly higher for C0 than C2 (P < .001). The CsA concentrations both at C0 and C2 were significantly higher with FPIA than with RIA (P < .009) but no differences were found for EMITT (P = .2). The mean C0 level for FPIA was 22% and 26% higher than RIA and EMIT, respectively. The mean C2, for FPIA was 7% and 12% higher than RIA and EMIT, respectively. In conclusion, CsA levels determined using RIA or EMIT are better than using FPIA/Tx; also, C2 CsA levels are more accurate than C0 in pediatric transplantation patients.