Dietary and Antioxidant Vitamins Limit the DNA Damage Mediated by Oxidative Stress in the Mother-Newborn Binomial.

During pregnancy, appropriate nutritional support is necessary for the development of the foetus. Maternal nutrition might protect the foetus from toxic agents such as free radicals due to its antioxidant content. In this study, 90 mothers and their children were recruited. DNA damage mediated by oxidative stress (OS) was determined by the levels of 8-hidroxy-2'-deoxyguanosine (8-OHdG) in the plasma of women and umbilical cord blood. The mothers and newborns were categorised into tertiles according to their 8-OHdG levels for further comparison. No relevant clinical differences were observed in each group. A strong correlation was observed in the mother−newborn binomial for 8-OHdG levels (Rho = 0.694, p < 0.001). In the binomial, a lower level of 8-OHdG was associated with higher consumption of calories, carbohydrates, lipids, and vitamin A (p < 0.05). In addition, the levels of 8-OHdG were only significantly lower in newborns from mothers with a higher consumption of vitamin A and E (p < 0.01). These findings were confirmed by a significant negative correlation between the 8-OHdG levels of newborns and the maternal consumption of vitamins A and E, but not C (Rho = −0.445 (p < 0.001), −0.281 (p = 0.007), and −0.120 (p = 0.257), respectively). Multiple regression analysis showed that the 8-OHdG levels in mothers and newborns inversely correlated with vitamin A (ß = −1.26 (p = 0.016) and −2.17 (p < 0.001), respectively) and pregestational body mass index (ß = −1.04 (p = 0.007) and −0.977 (p = 0.008), respectively). In conclusion, maternal consumption of vitamins A and E, but not C, might protect newborns from DNA damage mediated by OS.

Limited sampling strategy to predict the area under the curve of tacrolimus in Mexican renal transplant pediatric patients receiving Prograf® or non-innovator formulations.

TDM of tacrolimus is usually performed with trough levels (C0h ). However, in pediatric patients, C0h may not be an adequate marker. The AUC is considered a more suitable indicator of drug exposure. As several blood samples are needed for the estimation of AUC, and LSS for predicting tacrolimus AUC and optimizing the dose adjustment have been proposed. Moreover, in emerging countries such as Mexico, non-innovator formulations, which bioequivalence has not been demonstrated, are frequently used. Hence, the aim of this study was to develop and validate a LSS to predict the tacrolimus AUC0-12h in Mexican pediatric kidney transplant recipients who received either Prograf® or non-innovator tacrolimus formulations. A total of 56 pharmacokinetic profiles were randomized into two groups: model development (n = 28) and model validation (n = 28). The limited sampling equations were obtained after a stepwise multiple regression using AUC as the dependent variable and tacrolimus blood concentrations, quantified by CMIA, at different time points as the independent variables. The final equation included observed concentrations at 1 hour (C1h ) and 4 hours (C4h ) after dose administration. The predictive performance of the model was adequate in terms of both, bias and precision. Results strongly suggest that the clinical use of this LSS could provide an ethical, cost-, and time-effective method in the TDM of tacrolimus in pediatric patients with kidney transplant. The model proved to be adequate with either Prograf® or non-innovator tacrolimus formulations of dubious bioequivalence.

Population pharmacokinetic analysis of tacrolimus in Mexican paediatric renal transplant patients: role of CYP3A5 genotype and formulation.

AIMS: The aims of this study were (i) to develop a population pharmacokinetic (PK) model of tacrolimus in a Mexican renal transplant paediatric population (n = 53) and (ii) to test the influence of different covariates on its PK properties to facilitate dose individualization. METHODS: Population PK and variability parameters were estimated from whole blood drug concentration profiles obtained at steady-state using the non-linear mixed effect modelling software NONMEM® Version 7.2. RESULTS: Tacrolimus PK profiles exhibited high inter-patient variability (IPV). A two compartment model with first order input and elimination described the tacrolimus PK profiles in the studied population. The relationship between CYP3A5 genotype and tacrolimus CL/F was included in the final model. CL/F in CYP3A5*1/*1 and *1/*3 carriers was approximately 2- and 1.5-fold higher than in CYP3A5*3/*3 carriers (non-expressers), respectively, and explained almost the entire IPV in CL/F. Other covariates retained in the final model were the tacrolimus dose and formulation type. Limustin® showed markedly lower concentrations than the rest of the formulations. CONCLUSIONS: Population PK modelling of tacrolimus in paediatric renal transplant recipients identified the tacrolimus formulation type as a significant covariate affecting the blood concentrations and confirmed the previously reported significant effect of CYP3A5 genotype on CL/F. It allowed the design of a proposed dosage based on the final model that is expected to help to improve tacrolimus dosing.

Limustin®, a non-innovator tacrolimus formulation, yields reduced drug exposure in pediatric renal transplant recipients.

The aim of this study was to evaluate the bioavailability of two oral tacrolimus formulations, the innovator Prograf(®) and a formulation commercialized in Mexico with the brand name Limustin(®), in children. Stable Mexican pediatric renal transplant recipients received the product authorized by their social security provider, being either Prograf(®) or Limustin(®). At steady state, blood samples were drawn and tacrolimus blood concentration against time curves was constructed. CYP3A5 genotype was also determined. There was no significant difference in dose or in trough concentrations between formulations. However, AUC and Cmax were significantly higher with Prograf(®). The lower tacrolimus bioavailability with Limustin(®) was observed in both expressers and non-expressers of the functional CYP3A5 protein. Dose-normalized AUC values in expressers were 12.7 ± 11.9 and 48.7 ± 20.4 ng·h/mL/mg for Limustin(®) and Prograf(®), whereas in non-expressers, dose-normalized AUC was 54.4 ± 49.1 and 110.4 ± 42.9 ng·h/mL/mg for Limustin(®) and Prograf(®), respectively (p < 0.05). Pharmaceutical quality analysis showed that Limustin(®) dissolution at 120 min was 31.1 ± 6.2% while Prograf(®) dissolution was 100 ± 4.8%. Furthermore, the mean percentage of labeled amount of Limustin(®) and Prograf(®) was 91.0 ± 3.1% and 100.0 ± 0.7%, respectively. Hence, Limustin(®) exhibits pharmaceutical characteristics dissimilar to the innovator that likely explain the reduced tacrolimus exposure in children. We consider Limustin(®) is not adequate for pediatric use.

Bioavailability of a generic of the immunosuppressive agent mycophenolate mofetil in pediatric patients.

The use of generic immunosuppressive agents is controversial, especially for the treatment of pediatric patients, as information on the bioavailability of generic immunosuppressants in children is particularly scarce. The aim of the study was to compare the bioavailabilities of two products containing mycophenolate mofetil, the innovator and a generic, in children. Pediatric patients with end-stage renal disease on the waiting list for renal transplantation received a single oral dose of mycophenolate mofetil as either the innovator product (CellCept(®) , Roche) or the generic (Tevacept(®) , Teva Pharmaceuticals). A nine point pharmacokinetic profile was obtained. Mycophenolic acid concentration was quantitated in plasma by HPLC, plasma concentration-against-time curves were constructed, and bioavailability parameters were determined. Pharmaceutical quality analysis of both formulations, including drug content and dissolution profile, was also performed. There were no statistically significant differences between formulations in bioavailability parameters. Interindividual variability was very important, but individual values of AUC, an indicator of the extent of drug absorption, were within the same range for both formulations. The two formulations exhibited similar drug content and dissolution profiles, as well as comparable mycophenolic acid plasma levels in an end-stage renal failure population.

CYP3A5 polymorphism in Mexican renal transplant recipients and its association with tacrolimus dosing.

BACKGROUND AND AIMS: Variability in CYP3A5 expression associated with differences in tacrolimus bioavailability has been documented. The wild-type allele CYP3A5*1 expresses the functional protein, whereas the CYP3A5*3 allele is a splice variant with a premature stop codon and encodes a truncated nonfunctional protein. The aim of the study was to determine the frequency of CYP3A5*1 and CYP3A5*3 in 291 (124 adults, 167 pediatric) Mexican renal transplant recipients, evaluate the tacrolimus dose requirements by genotype and compare genotype frequency data with that of other populations. METHODS: We carried out a multicenter study. Patients were recruited from three institutions located in Mexico City. Genotyping of the CYP3A5*1 and CYP3A5*3 alleles was performed by direct DNA sequencing. RESULTS: Eighteen patients (6.2%) were CYP3A5*1*1 homozygous carriers or functional protein expresser homozygous, 121 patients (41.6 %) were CYP3A5*1*3 were heterozygous carriers or heterozygous expressers, and 152 patients (52.2%) were CYP3A5*3*3 homozygous carriers or homozygous nonexpressers. There was a statistically significant difference in frequency of the functional and nonfunctional expresser phenotypes from those reported for Black and Caucasian, but not for South Asian populations. The CYP3A5 phenotype had a significant impact in tacrolimus bioavailability, as wild-type carriers required higher dosing compared to mutated carriers to achieve similar drug trough levels. Patients with CYP3A5*1*1 genotype had a median dose requirement of 0.16 mg/kg/day, CYP3A5*1*3 patients had a median tacrolimus dose of 0.13 mg/kg/day and CYP3A5*3*3 had a median dose of 0.07 mg/kg/day (Kruskal-Wallis, p <0.0001). CONCLUSIONS: Of the Mexican transplant recipients, 52.2% were CYP3A5*3*3 and required significantly lower tacrolimus dose than those with CYP3A5*1 allele.

Maximal thermogenic capacity and non-shivering thermogenesis in the South American subterranean rodent Ctenomys talarum.

Subterranean rodents inhabit closed tunnel systems that are hypoxic and hypercapnic and buffer aboveground ambient temperature. In contrast to other strictly subterranean rodents, Ctenomys talarum exhibits activity on the surface during foraging and dispersion and hence, is exposed also to the aboveground environment. In this context, this species is a valuable model to explore how the interplay between underground and aboveground use affects the relationship among basal metabolic rate (BMR), cold-induced maximum metabolic rate (MMR), shivering (ST), and non-shivering thermogenesis (NST). In this work, we provide the first evidence of the presence of NST, including the expression of uncoupling proteins in brown adipose tissue (BAT), and shivering thermogenesis in Ctenomys talarum, a species belonging to the most numerous subterranean genus, endemic to South America. Our results show no differences in BMR, cold-induced MMR, and NST between cold- (15 °C) and warm- (25 °C) acclimated individuals. Furthermore, thermal acclimation had no effect on the expression of mitochondrial uncoupling protein 1 (UCP1) in BAT. Only cytochrome c oxidase (COX) content and activity increased during cold acclimation. When interscapular BAT was removed, NST decreased more than 30%, whereas cold-induced MMR remained unchanged. All together, these data suggest that cold-induced MMR reaches a maximum in warm-acclimated individuals and so a probable ceiling in NST and UCP1 expression in BAT. Possible thermogenic mechanisms explaining the increase in the oxidative capacity, mediated by COX in BAT of cold-acclimated individuals and the role of ST in subterranean life habits are proposed.

Prevalence of metabolic syndrome and obesity in renal transplanted Mexican children.

The purpose of the study was to evaluate the prevalence of MS and obesity in Mexican children with more than one yr post-renal transplantation. Thirty-two children transplanted between January 2004 and February 2006 were included in the study. The weight and height at the time of renal transplant were obtained. A fasting blood sample was drawn for serum creatinine, adiponectin, and complete lipid profile, and a three-h glucose tolerance test was also taken. A complete nutritional evaluation was performed including anthropometry. There was a statistically significant increase in BMI at one yr post-transplant that was maintained at two yr post-transplant. Three patients exhibited obesity and were overweight. Seventeen patients had hypertension, 14 patients had low HDL, 12 patients had hypertriglyceridemia, all had normal fasting glucose, six of them had glucose intolerance, and two had waist circumference higher than 90%. Eight patients (25%) had MS. Patients with MS had higher proportion of deceased donor grafts, acute rejection episodes, and received more methylprednisolone pulses; also they had a statistically significant higher pretransplant BMI than patients without MS. There was a significant relationship between BMI at one yr post-renal transplant and creatinine clearance estimated by Schwartz formula.

Síndrome de Alport / Alport syndrome

El síndrome de Alport (SA) es una enfermedad hereditaria de las membranas basales, debida a mutaciones en la colágena tipo IV. Clínicamente se caracteriza por nefropatía hereditaria progresiva, comúnmente asociada a sordera sensorial y/o lesiones oculares y, en ocasiones, leiomiomatosis. Constituye de 1-2% de las causas de enfermedad renal terminal en Europa y aproximadamente 3% en la población pediátrica americana. Existen tres formas genéticas de SA: 1. Ligado al cromosoma X, debido a mutaciones en el gen COL4A5. Esta forma se presenta en aproximadamente 80-85% de los pacientes. 2. Autosómico recesivo, debido a mutaciones en ambos alelos (homocigotos) de los genes COL4A3 ó COL4A4, ubicado en el cromosoma 2q35-37. Se presenta aproximadamente en 15% de las familias. 3. Autosómico dominante, debido a una mutación heterocigota de los genes COL4A3 ó COL4A4. Se presenta aproximadamente en 5% de las familias. La evolución depende del género y de factores genéticos. Se expone la fisiopatología de la enfermedad desde el punto de vista genético y bioquímico, así como las manifestaciones clínicas e histopatológicas, estrategias de diagnóstico y las opciones terapéuticas.

Alport syndrome (AS) is a hereditary disease of basal membranes due to a mutation in type IV collagen. It is characterized by hereditary progressive nephropathy often associated with sensorineural hearing loss, ocular defects and less commonly leiomyomatosis. It accounts for 1-2% of end stage renal disease patients in Europe and approximately 3% of end stage renal disease children in America. There are 3 genetic forms of AS: 1. X-linked, due to mutation in COL4A5 gene, present in 80-85% of patients. 2. Autosomal recessive, due to mutations in both alleles of COL4A3 or COL4A4 located in the 2q35-37 chromosome, present in 15% of families with Alport syndrome. 3. Autosomal dominant, due to a heterozygous mutation in COL4A3 or COL4A6 genes, it is present in 5% of the patients. The disease genetics, biochemistry, clinical presentation, histopathology, diagnosis, prognosis and therapeutic options are reviewed.

Púrpura de Henoch-Schönlein: Reporte de 105 pacientes pediátricos / Henoch-Schönlein purpura in children: Report of 105 patients

Introducción. La púrpura de Henoch-Schönlein (PHS) es la vasculitis más frecuente en niños. Objetivo: conocer la presentación clínica y evolución de los pacientes con PHS que se han tratado en el hospital en los últimos 5 años. Material y métodos. Estudio retrospectivo en pacientes que acudieron al Hospital Infantil de México Federico Gómez, del 1 de enero de 2000 al 31 de diciembre de 2005, con diagnóstico de PHS. Resultados. Se encontraron 105 pacientes con una mediana de edad de 6 años. El tiempo promedio de seguimiento fue de 15 meses. Todos presentaron lesiones dérmicas, 49.5% dolor abdominal y 41% artritis; 45 (42.9%) pacientes manifestaron nefropatía, con un promedio de aparición de 4.5 meses después de las lesiones dérmicas. Sólo en 37.7% de los casos con nefropatía desaparecieron las alteraciones urinarias. Se realizó biopsia renal en 14 pacientes. La lesión histopatológica más frecuente fue el grado IIIA. La edad de presentación tuvo relación estadísticamente significativa con la presencia de nefritis, los mayores de 10 años tuvieron mayor incidencia de nefritis y los menores de 5 años menor incidencia (Chi cuadrada, P < 0.05). La incidencia global de insuficiencia renal crónica fue de 0.95%. Conclusión. La edad de presentación es un factor pronóstico para la evolución de la enfermedad. Si bien la púrpura es una vasculitis, la principal complicación a largo plazo es renal, por lo que el seguimiento de los pacientes debe ser supervisado por un nefrólogo pediatra.

Introduction. Henoch-Schönlein purpura (HSP) is the most frequent vasculitis in children. Objective: To describe the clinical presentation and clinical outcome in children with HSP treated in our hospital in the last 5 years. Material and methods. A retrospective study was performed in HSP patients diagnosed between January 1st 2001 and December 31st 2005. Results. HSP was diagnosed in 105 patients, median age 6 years old. All had the skin manifestations, 49.5% abdominal pain and 41% arthritis; 45 patients developed HSP nephritis (42.9%), mean presentation time was 4.5 months after HSP diagnosis. Renal biopsy was performed in 14 patients, and the most common histopathological finding was HSP nephritis grade III A. Age of onset older than 10 years was statistically significant for nephritis development (Chi Square < 0.05). Chronic renal insufficiency incidence was 0.95%. Conclusions. The main complication of HSP is nephritis. Follow-up should include evaluation by a pediatric nephrologist. Age of onset older than 10 years is an important risk factor for HSP nephritis.

In vitro antimicrobial susceptibility in clinical isolates of Enterococcus species.

OBJECTIVE: To describe the antimicrobial activity of several antimicrobial agents against 97 clinical significant isolates of Enterococcus spp. MATERIAL AND METHODS: During a 2-year prospective study at Instituto Nacional de Pediatria (National Institute of Pediatrics) in Mexico City. Ninety seven strains of Enterococcus spp. (60 E faecalis and 37 E. faecium) were tested against 11 antibiotics. Susceptibility tests were performed with agar, according to the standards of the sNational Committee for Clinical Laboratory Standards (NCCLS). Isolates were screened for high-level resistance (HLR) to beta-lactams, aminoglycosides, glycopeptides and other antibiotics, as well as for vancomycin-phenotypes. Differences between proportions were evaluated with chi 2 of Fisher exact fest. RESULTS: Overall resistance rates to the antibiotics tested were: 17/97 (17.5%) to penicillin, ampicillin, amoxicillin-clavulanate and imipenem. There was neither HLR nor beta-lactamase production; 74/97 (48.4%) were resistant to erythromycin; 60% to ciprofloxacin; 31/97 (32%) to gentamicin, and 55/97 (56.7%) to streptomycin. Seven strains were vancomycin-resistant enterococci (VRE), all of them identified as E. faecium; 5/7 with Van A and 2/7 with Van B phenotypes. All the isolates were susceptible to linezolid. The difference in susceptibility among species was significant. CONCLUSIONS: Mutidrug-resistant enterococci is a real problem and continuous surveillance is necessary. The microbiology laboratory is the first line of defense against the spread of multiantibiotic-resistan enterococci in the hospital environment. All the strains recovered should be tested for susceptibility to ampicillin, streptomycin, gentamicin and glycopeptides. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.

In vitro antimicrobial susceptibility in clinical isolates of Enterococcus species

OBJECTIVE: To describe the antimicrobial activity of several antimicrobial agents against 97 clinical significant isolates of Enterococcus spp. MATHERIAL AND METHODS: During a 2-year prospective study at Instituto Nacional de Pediatria (National Institute of Pediatrics) in Mexico City. Ninety seven strains of Enterococcus spp. (60 E. faecalis and 37 E. faecium) were tested against 11 antibiotics. Susceptibility tests were performed with agar, according to the standards of the sNational Committee for Clinical Laboratory Standards (NCCLS). Isolates were screened for high-level resistance (HLR) to beta-lactams, aminoglycosides, glycopeptides and other antibiotics, as well as for vancomycin-phenotypes. Differences between proportions were evaluated with chi2 of Fisher exact fest. RESULTS: Overall resistance rates to the antibiotics tested were: 17/97 (17.5 percent) to penicillin, ampicillin, amoxicillin-clavulanate and imipenem. There was neither HLR nor beta-lactamase production; 74/97 (48.4 percent) were resistant to erythromycin; 60 percent to ciprofloxacin; 31/97 (32 percent) to gentamicin, and 55/97 (56.7 percent) to streptomycin. Seven strains were vancomycin-resistant enterococci (VRE), all of them identified as E. faecium; 5/7 with Van A and 2/7 with Van B phenotypes. All the isolates were susceptible to linezolid. The difference in susceptibility among species was significant. CONCLUSIONS: Mutidrug-resistant enterococci is a real problem and continuous surveillance is necessary. The microbiology laboratory is the first line of defense against the spread of multiantibiotic-resistan enterococci in the hospital environment . All the strains recovered should be tested for susceptibility to ampicillin, streptomycin, gentamicin and glycopeptides