Identification of multiple strains of Porphyromonas gingivalis using heteroduplex polymerase chain reaction in varying severity of chronic periodontitis

Aim: Research has demonstrated that there are multiple strains of Porphyromonas gingivalis with varying potency to cause periodontal disease. The current study aims at using heteroduplex polymerase chain reaction (PCR) to detect the strain diversity of P. gingivalis in periodontitis lesions of varying severity in a sample of the Indian population. Materials and Methods: Subgingival plaque samples were collected from 60 individuals with varying severity of chronic periodontitis and 30 individuals with a clinically healthy periodontium. The samples were subjected to PCR analysis to identify P. gingivalis, followed by heteroduplex analysis to identify the strain diversity in a given sample. Bacterial culture was carried out as a comparative standard. Results: Of the 56 samples that were positive for P. gingivalis by PCR, 54 samples yielded eight different heteroduplex patterns. Analysis of these patterns indicated that two strains of P. gingivalis were present in 41 individuals (45.6%) and three strains were present in 13 individuals (14.4%). Detection of P. gingivalis by PCR was significantly more in the periodontitis group as compared to the healthy group. Conclusions: Species-specific PCR and heteroduplex analysis provide a simple and accurate method to analyse the strain diversity of P. gingivalis. P. gingivalis was detected in both healthy periodontal sites as well as sites with periodontitis. The presence of two or three P. gingivalis strains was seen in 60% of the samples.

PCR-heterodúplex por agrupamiento: implementación de un método de identificación de portadores de la mutación más común causal de fibrosis quística en Colombia / PCR-heteroduplex by grouping: rapid screening carrier method for cystic fibrosis F508del mutation in Colombia

Introducción: La fibrosis quística (FQ) es una enfermedad autosómica recesiva frecuente, con una incidencia de 1 en 2,500 recién nacidos. La causan más de 1,300 mutaciones distintas en el gen regulador de la conductancia transmembranal de la fibrosis quística (CFTR). Sin embargo, la mutación F508del es la más común en la mayoría de las poblaciones. Objetivos: Desarrollo de una técnica rápida, de bajo costo y confiable que permita filtrar con rapidez a los portadores o afectados por esta mutación que mediante el asesoramiento genético, contribuya a disminuir la aparición de nuevos casos y a un diagnóstico temprano de los enfermos y así lograr un descenso en la morbilidad y la mortalidad asociadas con la fibrosis quística en Colombia. Metodología: En el presente estudio se aplicó la técnica PCR-heterodúplex por agrupamientos, gracias al análisis de 400 muestras de sangre en papel filtro obtenidas de individuos asintomáticos para la FQ. Resultados: En las pruebas de validación de la técnica PCR-heterodúplex por agrupamiento se obtuvo una eficiencia, reproducibilidad y especificidad de 100% y una sensibilidad de 92%. Conclusiones: Se demostró la sensibilidad y reproducibilidad de la técnica PCR Directa-heterodúplex por agrupamientos de hasta 10 muestras, que se pueden emplear en programas para filtrar heterocigotos y afectados de F508del.

Background: Cystic fibrosis (CF) is the most frequent autosomal recessive disorder in the Caucasian population with an incidence of 1 in 2,500 newborns. More than 1,300 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that causes CF have been described. However, mutation F508del is the most common mutation in different populations around the world. Objective: To develop a fast, reliable and low-cost technique to screen carriers and affected individuals for the F508del mutation. This kind of analysis will have an impact on genetic counselling to decrease the incidence of new cases, in the early diagnosis and instauration of appropriate treatment to decrease morbidity and mortality associated to CF in Colombia. Methods: The reliability of the PCR-heteroduplex by grouping technique by analysis of 400 blood spot samples from asymptomatic CF patients was defined. Results: Using PCR-heteroduplex by grouping technique 100% efficiency, reproducibility and specificity and 92%sensitivity were found.Conclusions: The sensitivity and reproducibility of the PCR-heteroduplex by grouping technique up to pooling of 10 samples were demonstrated. This kind of analysis could be used in heterozygotes and affected screening programs.

Polymerase Chain Reaction and Heteroduplex Analysis Based Detection of Clonal T Cell Receptor Gamma Gene Rearrangements in Paraffin-embedded Tissues of Cutaneous T Cell Proliferative Diseases

BACKGROUND: Recently, the molecular pathologic investigation for clonality in lymphomas has been introduced and has gained a role in the diagnosis of lymphomas. In fact, the clonality test using TCRGR phenomenon has been done by Southern blot analysis (SBA) and polymerase chain reaction (PCR) for molecular pathologic diagnosis of T cell lymphomas. However, it is difficult to perform SBA with paraffin embedded specimens or with samples of small skin biopsies. OBJECTIVE: We investigated the efficacy of PCR amplification of TCR gene in paraffin em-bedded cutaneous T cell lymphomas. METHODS: Iii this study, the clonality was assessed by polymerase chain reaction (PCR) analysis of T cell receptor gamma (TCR) gene from the DNA extracts obtained from paraffin em-bedded tissues (PET) of malignant T cells, B cell lymphomas, and benign cutaneous T cell proliferative disorders. Heteroduple-x-analyses were also performed to rule out the false positives. RESULTS: Among the total of 62 cases analyzed, monoclonality was observed in 4 out of 10 mycosis fungoides, 7 out of 9 cutaneous T cell lymphomas excluding mycosis fungoides, 1 out of 3 angiocentric lymphomas, 2 out of 2 lymphomatosis papulosis, 1 out of 7 large plaque parapsoriasis, and 1 out of 2 T cell lymphomas in other organs. No monoclonality was observed in 9 inflammatory cutaneous diseases, 5 small plaque parapsoriasis, 4 cutaneous B cell lymphomas, and 11 B cell lymphomas in lymph nodes. CONCLUSION: The results suggest that the PCR method and heteroduplex analysis used in this study were not only practical but also efficacious for the diagnosis of cutaneous T cell lymphomas using tissues embedded in paraffins.