Characterization of Phenyalanine Hydroxylase Gene Mutations in Chilean PKU Patients.

Phenylketonuria (PKU, OMIM 261600) is an autosomal recessive disease, caused by mutations in the Phenylalanine Hydroxylase (PAH) gene situated in chromosome 12q22-q24.2. This gene has 13 exons. To date, 991 mutations have been described. The genotype is one of the main factors that determine the phenotype of this disease. OBJECTIVE: Characterize PKU genotype and phenotype seen in Chilean PKU patients. METHODS: We studied the PAH gene by restriction fragment length polymorphism (RFLP) and/or sequencing techniques to identify pathogenic mutations in 71 PKU subjects. We classified the phenotype according to Guldberg predicted value. RESULTS: We identified 26 different mutations in 134 of the 142 alleles studied (94.4%), 88.7% of the subjects had biallelic pathogenic mutations while 11.3% had only one pathogenic mutation identified. Compound heterozygous represented 85.9% of the cases. Exon 7 included the majority of mutations (26.9%) and 50% of mutations were missense. The most frequent mutations were c.1066-11G > A, c.442-?_509+?del and p.Val388Met. The majority of subjects (52.3%) had the classic phenotype. CONCLUSIONS: The most frequent mutations in our Chilean PKU population were p.Val388Met, c.442?_509+?del and c.1066-11G > A. It is possible to predict phenotype by detecting the genotype, and use this information to determine disease prognosis and adjust patient's medical and nutritional management accordingly.

Aspectos clínicos, moleculares y farmacológicos en los trastornos asociados a gen 1 del retraso mental del X frágil / Clinical, molecular, and pharmacological aspects of FMR1 related disorders

Introducción. El síndrome X frágil (SXF) es la causa más frecuente de discapacidad intelectual hereditaria y se asocia a un amplio espectro de enfermedades en las distintas generaciones de una misma familia. En este trabajo se revisan las manifestaciones clínicas de los trastornos asociados al X frágil y el espectro de mutaciones en el gen 1 del retraso mental del X frágil (FMR1), la neurobiología de la proteína del retardo mental X frágil (FMRP) y una visión general de los potenciales blancos terapéuticos y el asesoramiento genético. Desarrollo. Esta enfermedad es causada por una amplificación de las repeticiones CGG (>200 repeticiones) en la región 5’ no traducida del gen FMR1, que lleva al déficit o ausencia de la proteína FMRP. La FMRP es una proteína de unión al ARN que regula la traducción de varios genes que son importantes en la plasticidad sináptica y la maduración dendrítica. Se cree que expansiones de las repeticiones CGG en el rango de premutación (55-200 repeticiones) generan un aumento en los niveles de mRNA de FMR1, lo que produciría toxicidad neuronal. Esto se manifiesta en problemas del desarrollo tales como autismo y problemas de aprendizaje, así como en patologías neurodegenerativas como el síndrome de temblor/ataxia asociado al X frágil (FXTAS). Conclusiones. Los avances en la identificación de las bases moleculares del SXF pueden servir como modelo para comprender las causas de las enfermedades neuropsiquiátricas y probablemente conducirán al desarrollo de tratamientos cada vez más específicos (AU)

Background. Fragile X syndrome, the most common inherited cause of intellectual disability, is associated with a broad spectrum of disorders across different generations of a single family. This study reviews the clinical manifestations of fragile X-associated disorders as well as the spectrum of mutations of the fragile X mental retardation 1 gene (FMR1) and the neurobiology of the fragile X mental retardation protein (FMRP), and also provides an overview of the potential therapeutic targets and genetic counselling. Development. This disorder is caused by expansion of the CGG repeat (>200 repeats) in the 5 prime untranslated region of FMR1, resulting in a deficit or absence of FMRP. FMRP is an RNA-binding protein that regulates the translation of several genes that are important in synaptic plasticity and dendritic maturation. It is believed that CGG repeat expansions in the premutation range (55 to 200 repeats) elicit an increase in mRNA levels of FMR1, which may cause neuronal toxicity. These changes manifest clinically as developmental problems such as autism and learning disabilities as well as neurodegenerative diseases including fragile X-associated tremor/ataxia syndrome (FXTAS). Conclusions. Advances in identifying the molecular basis of fragile X syndrome may help us understand the causes of neuropsychiatric disorders, and they will probably contribute to development of new and specific treatments (AU)

Clinical, molecular, and pharmacological aspects of FMR1 related disorders. / Aspectos clínicos, moleculares y farmacológicos en los trastornos asociados a gen 1 del retraso mental del X frágil.

BACKGROUND: Fragile X syndrome, the most common inherited cause of intellectual disability, is associated with a broad spectrum of disorders across different generations of a single family. This study reviews the clinical manifestations of fragile X-associated disorders as well as the spectrum of mutations of the fragile X mental retardation 1 gene (FMR1) and the neurobiology of the fragile X mental retardation protein (FMRP), and also provides an overview of the potential therapeutic targets and genetic counselling. DEVELOPMENT: This disorder is caused by expansion of the CGG repeat (>200 repeats) in the 5 prime untranslated region of FMR1, resulting in a deficit or absence of FMRP. FMRP is an RNA-binding protein that regulates the translation of several genes that are important in synaptic plasticity and dendritic maturation. It is believed that CGG repeat expansions in the premutation range (55 to 200 repeats) elicit an increase in mRNA levels of FMR1, which may cause neuronal toxicity. These changes manifest clinically as developmental problems such as autism and learning disabilities as well as neurodegenerative diseases including fragile X-associated tremor/ataxia syndrome (FXTAS). CONCLUSIONS: Advances in identifying the molecular basis of fragile X syndrome may help us understand the causes of neuropsychiatric disorders, and they will probably contribute to development of new and specific treatments.

Nanomedicine and its applications to the treatment of prostate cancer.

In recent years, nanotechnology has been the focus of considerable attention in medicine due to the facility with which nanostructures interact with the body at the molecular scale. New therapies in cancer research using nanomedicine are being developed in order to improve the specificity and efficacy of drug delivery, thus reaching maximal effectiveness with minimal side effects. This literature review presents cases of prostate cancer in antiquity as well as the first modern reports before discussing how nanotechnology can contribute to the management of this disease. Three major nanoparticle-based platforms are described: liposomal, polymeric and metallic. Published results, including therapies in current clinical trials, are discussed. In addition, several formulations of microparticles containing LH-RH analogues approved by the authorities are listed in this document. A critical analysis of the health and environmental impact is made to highlight the need for precise control of the utilization of nanomaterials.

FXTAS in an unmethylated mosaic male with fragile X syndrome from Chile.

Carriers of an FMR1 premutation allele (55-200 CGG repeats) often develop the neurodegenerative disorders, fragile X-associated tremor/ataxia syndrome (FXTAS). Neurological signs of FXTAS, parkinsonism and rapid onset of cognitive decline have not been reported in individuals with an unmethylated full mutation (FM). Here, we report a Chilean family affected with FXS, inherited from a parent carrier of an FMR1 unmethylated full mosaic allele, who presented with a fast progressing FXTAS. This case suggests that the definition of FXTAS may need to be broadened to not only include those with a premutation but also those with an expanded allele in FM range with a lack of methylation leading to elevated FMR1-mRNA expression levels and subsequent RNA toxicity.

Rapid quantification of malondialdehyde in plasma by high performance liquid chromatography-visible detection.

BACKGROUND: Malondialdehyde (MDA) is one of the better-known secondary products of lipid peroxidation, and it is widely used as an indicator of cellular injury. The employment of the thiobarbituric acid reactive substances (TBARS) technique to measure MDA has received criticism over the years because of its lack of specificity. Thus, a specific and reliable method for MDA determination in plasma by high performance liquid chromatographic (HPLC)-VIS was validated; alkaline hydrolysis, n-butanol extraction steps and MDA stability were established. METHODS: The plasma underwent alkaline hydrolysis, acid deproteinization, derivatization with TBA and n-butanol extraction. After this, MDA was determined at 532 nm by HPLC-VIS. The method was applied to 65-year-old subjects from a retirement home. RESULTS: The assay was linear from 0.28 to 6.6 microM. The reproducibility of intra-run was obtained with CV%<4% and the inter run with CV%<11%. The accuracy (bias) ranged from 2 to -4.1%, and the recovery was greater than 95%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.05 and 0.17 microM, respectively. For the stability test, every sample was stored at -20 degrees C. The plasma MDA was not stable when stored after the alkaline hydrolysis step, remained stable for 30 days after TBA derivatization storage and was stable for 3 days when stored after n-butanol extraction. The elderly subjects had MDA plasma levels of 4.45+/-0.81 microM for women and 4.60+/-0.95 microM for men. CONCLUSION: The method is reproducible, accurate, stable, sensitive, and can be used in the routines in clinical laboratories. Besides, this technique presents advantages such as the complete release of protein bound MDA with the alkaline hydrolysis step, the removal of interferents with n-butanol extraction, mobile phase without phosphate buffer and rapid analytical processes and run times.

Analysis of networks based on styrene and divinylbenzene containing iron anchored using variable pressure scanning electron microscopy.

There is great demand for the development of composite materials containing small metal or metal oxides particles, owing to their variable properties and wide application. However, microscopic evaluation of these materials using high-vacuum scanning electron microscopy is difficult because the samples must undergo a series of preparation steps to reach a high image quality and to avoid becoming shrunk inside the microscope vacuum chamber. Thus, in this study, we used variable pressure scanning electron microscopy to evaluate the morphology and iron distribution on the surface of magnetic microspheres based on poly(styrene-co-divinylbenzene). These materials were obtained by suspension copolymerization of styrene and divinylbenzene in the presence of fine iron particles. Energy-dispersive X-rays were also used to analyse distribution of the iron particles. The results indicate that, under the conditions used, magnetic microspheres with a relatively narrow size distribution were formed. Moreover, the micrographs show that agglomerated iron particles appeared only on the microsphere surface.

[Molecular diagnosis of Prader-Willi and Angelman syndromes: methylation, cytogenetics and FISH analysis]. / Diagnóstico molecular de los síndromes de Prader-Willi y de Angelman: análisis de metilación, citogenética y FISH.

BACKGROUND: The diagnosis of Prader-Willi and Angelman syndromes is difficult, since their phenotypic manifestations are variable and unspecific. The study of the methylation state of DNA in 15(q11-q13) using polymerase chain reaction, called methylation test, allows the diagnosis of most patients with Prader-Willi and Angelman syndromes, irrespective if the underlying molecular alteration is a deletion, uniparental disomy or a punctual imprinting mutation. AIM: To assess the effectiveness of methylation test in the diagnosis of Prader-Willi and Angelman syndromes. PATIENTS AND METHODS: Thirty seven cases with a presumptive diagnosis of Prader-Willi syndrome and 25 with the presumptive diagnosis of Angelman syndrome were studied. Methylation test was done in genomic DNA obtained from peripheral lymphocytes. RESULTS: Methylation test confirmed the clinical diagnosis in 11 of 37 patients with Prader Willi (30%) and 6 of 25 patients with Angelman syndrome (24%). CONCLUSIONS: Clinical criteria overestimate the diagnosis of Prader-Willi and Angelman syndromes. The initial diagnosis should be confirmed with the methylation test and, if necessary, with FISH that will detect most deletions in the region.

[B-DR (HLA) linkage imbalance and transplants in Chile: a preliminary report]. / Desequilibrio de ligamento B-DR (HLA) y trasplantes en Chile: comunicación preliminar.

Linkage imbalance for the B and DR loci (HLA) was found in a Chilean sample of families where a member had been proposed for transplantation. The B7-DR2 and B14-DR1 haplotypes were significantly more frequent than expected. Most associations were those found in Caucasian populations.