Clinical application of covalently closed circular DNA detection techniques / 临床肝胆病杂志

Covalently closed circular DNA (cccDNA) is the original template for hepatitis B virus (HBV) replication and is the basis of persistent HBV infection. Only when HBV cccDNA is completely eliminated can HBV be eradicated. Therefore, the detection of HBV cccDNA plays an important role in evaluating the antiviral outcome of chronic hepatitis B, assessing HBV clearance, clarifying occult HBV infection, studying the pathogenesis of hepatitis B, and developing new drugs, and HBV cccDNA detection techniques with high sensitivity and specificity are the basis for clinical application. With reference to related reports in literature and our own research work, this article reviews the development and clinical application of HBV cccDNA detection methods in recent years.

DNA Typing of Sporothrix schenckii by Analysis of Ribosomal-DNA Regions / 中华皮肤科杂志

Objectives To identify genotypes of 31 Sporothrix schenckii (S.schenckii) strains by Southern blotting and to explore the relationship between genotypes and geographic distributions and clinical manifestations.Methods Total DNA was extracted by cetyltriethyl ammonium bromide (CTAB).The polymorphisms were detected by hybridization of ApaⅠ-digested S.schenckii genomic DNA with a probe amplified from the small-subunit rDNA and adjacent internal transcribed spacer (ITS) regions.The band patterns manifested by Southern blotting were employed to investigate genotypes of 31 strains of S.schenckii collected from five different areas in China.Results Of 31 strains of S.schenckii,15 individual patterns (DNA Type A-O) were recognized.Type A to C accounted for 51.61% of all strains.Conclusion The Southern blotting provides a highly sensitive and reliable means for DNA typing of S.schenckii.It is also found that there is an obvious correlation between DNA patterns and different geographic distribution and clinical manifestations.

Síndrome frágil X: correlación clínica, citogenética y molecular en una familia

Estudios recientes han permitido caracterizar molecularmente el defecto genético o mutación FMR-1 del síndrome frágil X. Esta mutación consiste en variaciones de repeticiones del triplete CGG del gen, que varían del rango normal a la mutación completa y pasan por rangos intermedios o premutaciones. Debido a que el individuo afectado además expresa un porcentaje variable de sitio frágil Xq27.3 (FRAXA) en su cariotipo, en este trabajo se presenta una correlación clínica y citogenética con la caracterización molecular del gen FMR-1 realizada por 2 métodos directos: Southern blot y reacción en cadena de la polimerasa (PCR) en 5 varones afectados y 5 mujeres portadoras, a propósito del diagnóstico prenatal en una de ellas. El análisis de las caracterizaciones clínicas, físicas y neuropsicológicas previamente delineadas, llevaron a la conclusión de que éstas, así como la frecuencia en porcentaje de FRAXA, se correlacionan en los varones afectados con la elongación que experimenta la mutación al trasmitirse de una generación a la siguiente a través de mujeres portadoras, en quienes por otra parte, estas características son heterogéneas y susceptibles a sobrelapamiento tanto por efecto genómico como por factores ambientales psicofamiliares.

Recent studies have allowed to characterize molecularly the genetic defect or FMR-1 mutation of the fragile X syndrome. This mutation consists in variations of repetitions of the gene's CGG triplet that came from the normal range to the complete mutation, passing through intermediate ranges or premutations. Due to the fact that the affected individual also shows a variable percentage of Xq27.3 fragile site (FRAXA) in his karyotype, it is presented in this paper a clinical and cytogenetic correlation with the molecular characterization of the FMR-1 gen carried out by 2 direct methods: Southern Blot and polymerase chain reaction (PCR) in 5 affected males and 5 female carriers, one of them with prenatal diagnosis. The analysis of the clinical, physical and neuropsychological characterizations previously delineated, led to the conclusion that these, as well as the FRAXA frequency in percentage, are correlated among the affected males with the elongation the mutation suffers on being transmitted from one generation to another through female carriers, in whom these characteristics are heterogeneous and susceptible to overlapping as a result of genomic effect and of environmental psychofamilial factors.

Diagnóstico molecular del Síndrome X Frágil en un grupo control y miembros de 3 familias afectadas

El síndrome X frágil constituye la forma de retraso mental hereditario más frecuente con una incidencia de 1 en 1 500 varones y de 1 en 2 500 hembras; es causado por mutaciones que aumentan el tamaño de un fragmento de ácido desoxinucleótico (DNA) específico en la región Xq 27.3 del cromosoma X. Se presenta el resultado en la introducción y aplicación de la sonda molecular StB12.3 en un grupo control y en miembros afectados de 3 familias. Se exponen las radiografías de los Southern blot que exhiben los patrones diagnósticos posibles a obtener. Esta metodología es mucho más directa, eficiente y confiable para el diagnóstico y prevención de esta forma de retraso mental.

The fragile X syndrome is the most frequent form of hereditary mental retardation, with an incidence of 1 in 1 500 males, and 1 in 2 500 females; it is caused by mutations that increase the size of a fragment of specific desoxinucleotic acid (DNA) in the Xq 27.3 region of the X chromosome. The outcome in the introduction and application of the StB12.3 molecular probe in a control group and in affected members of three families, is presented. The x-rays of the Southern blot that show the diagnosis patterns possible to obtain, are exposed. This methodology is more direct, effective and reliable for the diagnosis and prevention of this form of mental retardation.