Can the genetic variability of Blastocystis sp. be associated with the climatic region of its human carriers?

Blastocystis sp. is a widespread microorganism that colonizes the intestinal tract of several animals, including human beings, while its pathogenic role in humans is still under debate. The objective of the present study was to describe the frequency of Blastocystis sp. subtypes (STs) and their genetic variation within and among samples recovered from scholars inhabiting two rural villages with tropical climates and compare this information with previously documented data from arid and temperate zones in Mexico. Blastocystis sp. positive samples and ST identification were achieved by coprological analysis screening and Polymerase Chain Reaction-sequencing, respectively. Classical population genetics indexes (nucleotide diversity (π), haplotype polymorphism (θ), gene flow (Nm), genetic differentiation (ST), and Tajima's D) were calculated by comparing the sequences here obtained (n = 42) and those from previous studies from the arid (n = 80) and temperate (n = 61) climates from Mexico. Although Blastocystis sp. was the parasite most frequently found between 33% and 26% in both communities, only STs 1-3 were found. Haplotype network inference of Blastocystis sp. STs showed different haplotype profiles among STs vs. climate zones, although no specific haplotypes were identified for any particular climatic zone. Population genetics indexes showed different values within STs and climate zones (π and θ values ranged from 0.004 to 0.147; Nm > 4 and ST from 0.006 to 0.12). Our results show that Blastocystis sp. subtypes exhibit a different genetic variability profile according to the climate zone, suggesting a balancing process between the genetic variability within the Blastocystis sp. subtype and the number of haplotypes identified in each climate.

Mutations in the FGFR2 gene in Mexican patients with Apert syndrome.

Apert syndrome (AS) is a frequent acrocephalosyndactyly, with autosomal dominant inheritance. AS has been associated with mutations in fibroblast growth factor receptor 2 (FGFR2), and approximately 99% of cases show 2 of the frequent mutations located in exon IIIa (Ser252Trp or Pro253Arg). The purpose of the present study was to describe the mutations in exon IIIa of FGFR2 in Mexican AS patients and the relationships with clinical features. Exon IIIa of FGFR2 from 6 AS patients was amplified by polymerase chain reaction. Mutations in exon IIIa of the FGFR2 gene were identified by digestion with the restriction endonuclease Bstx1 and polyacrylamide gel electrophoresis. PCR fragments were cloned into the PCR 2.1 vector, and both DNA strands were sequenced using the T7 promoter and M13 universal cloning region oligonucleotides. Sequence alignment was performed using the MEGA software version 5. The patients' major clinical features included craniosynostosis, hypertelorism, proptosis, otitis media, midfacial hypoplasia, rhizomelic shortening, and hyperhidrosis. Mutation S252W was present in 4 patients, while the other 2 patients had P253R. In conclusion, either S252W or P253R mutations were present independently in AS patients; however, the 2 mutations were not found together. None of the clinical features were associated with any of the mutations, suggesting that other mutations may be involved in the development of this syndrome.

The epithelial mesenchymal transition process may contribute to the pathogenesis of amniotic band syndrome.

The etiology of the amniotic band syndrome is unknown, and has been subject of debate since the time of Hippocrates. The most accepted theories fail to cover all the abnomalities found in affected children. During organogenesis the epithelial-mesenchymal transition process (EMTP) participates in adequate formation of different organs from three embryo layers. Altered activation of EMTP occurs when the epithelial homeostasis is disturbed, the resulting myofibroblasts are able to secrete extracellular matrix proteins and deposit them on the tissues contributing to a fibrotic phenotype. If injury occurs during organogenesis, wound healing could be exaggerated and fibrotic response could be triggered. The molecule that regulates both of these processes (EMTP and fibrosis) is the transforming growth factor ß (TGFß); indeed null animals for TGFß isoforms show similar defects than those seen in the amniotic band syndrome. Based on documented evidence this review intends to explain how the epithelial mesenchymal transition process may contribute to the pathogenesis of amniotic band syndrome.

[Irritable bowel syndrome: frequency and phylogenetic relationship of Blastocystis sp. from Mexican patients]. / Síndrome de intestino irritable: frecuencia y relación filogenética de Blastocystis sp. de pacientes mexicanos.

INTRODUCTION: Recent studies reported increased presence of Blastocystis in patients with Irritable Bowel Syndrome (IBS) and an etiologic role has been proposed. The pathogenic role of Blastocystis is controversial, because it is frequently found not only in individuals with enteric symptoms but also in healthy and asymptomatic subjects. Furthermore, there are few studies of blastocistosis in Mexico. OBJECTIVE: To assess the frequency of Blastocystis sp. in IBS patients using molecular techniques and to describe its phylogenetic relationship with sequences of other countries. METHODS: IBS patients according to Rome III criteria were enrolled. In all patients evaluations included: colonoscopies, coproparasitoscopic studies, coproculture, fecal virus screening. PCR and sequencing for Blastocystis sp. were also performed. RESULTS: We recruited 11 men and 51 women with a mean age of 45.6 (SD ± 15.7) years. Eighty-six percent of the IBS patients presented a normal colonoscopy, 8% showed polyps and 6% diverticular disease. Blastocystis sp. was identified in 25% patients (all of them with normal colonoscopy), while two patients had Endolimax nana and Entamoeba histolytica/E. dispar, respectively. Phylogenetic analysis showed that major sequences of Mexican carriers clustered together with sequences of parasites from Japan and Denmark; furthermore, two sequences from IBS patients were grouped in a single cluster. CONCLUSIONS: Blastocystis sp. was identified in 25% of the IBS patients. Our data support the hypothesis of clonal lineages in distinct geographical areas in the world.

[Quantification of T CD4+ lymphocytes and viral RNA in patients with HIV/AIDS]. / Cuantificación de linfocitos T CD4+ y de RNA viral en pacientes con VIH/SIDA.

Quantification of CD4+ T lymphocytes and viral RNA in patients with HIV/AIDS. Levels of progression markers (viral load and CD4+ T lymphocytes) in 410 patients with HIV/AIDS that were in different clinical stages of the disease and under different therapeutic schemes were quantified. The objective was to determine the correlation between values of progression markers and clinical stage of the patients. Commercial methodologies for the quantification of lymphocytes, subpopulations and circulating viral RNA were used. Results indicate that there was a correlation between low CD4+ values and high viral load in patients with antiretroviral treatment but not in patients without treatment. Furthermore, analysis of 1,208 samples processed during 1999 showed that 46% of the patients had less than 200 CD4+ T lymphocytes/mL blood and more than 500 copies of circulating viral RNA. Implications of these results in public health in Mexico are discussed.