Contribution of polymorphisms in the LEP, LEPR and RETN genes on serum leptin and resistin levels in young adults from Mexico.

Polymorphisms in the LEP (G-2548A and A19G), LEPR (A326G, A668G and G3057A) and RETN (C-420G and G+62A) genes were documented according to their association with alterations in biochemical parameters such as glucose, insulin and lipid profiles, along with serum leptin and resistin concentrations. The aim of the study was to establish any contribution of the G-2548A and A19G polymorphisms of the LEP gene, the A326G, A668G and G3057A polymorphisms of the LEPR gene, and the C-420G and G+62A polymorphisms of the RETN gene to serum leptin and resistin levels in Mexican young adults. Clinical and biochemical variables, serum leptin and resistin levels, and genotype profiles were analysed in 66 Mexican young adults. Seven polymorphisms in the LEP, LEPR and RETN genes were genotyped using polymerase chain reaction-restriction fragment length polymorphisms analysis. Individuals carrying allele 3057A of the G3057A polymorphism in the LEPR gene showed significantly higher leptin concentrations than those bearing the genotype G/G (43.78 ± 39.11 vs 28.20 ± 14.12 ng/mL; p = 0.021). There were no associations of serum leptin or resistin levels according to the genotype of the other six analysed polymorphisms. Our results suggest that the allele 3057A of the LEPR G3057A polymorphism contributes to increased serum leptin levels in Mexican young adults.

Tumor necrosis factor haplotype diversity in Mestizo and native populations of Mexico.

The so-called tumor necrosis factor (TNF) block includes the TNFA, lymphotoxin alpha and beta (LTA and LTB) genes with single-nucleotide polymorphisms (SNP) and microsatellites with an allele frequency that exhibits interpopulation variability. To date, no reports have included both SNPs and microsatellites at the TNF block to study Mestizo or Amerindian populations from Mexico. In this study, samples of five Mexican Mestizo populations (Durango, Guadalajara, Monterrey, Puebla, and Tierra Blanca) and four native-Mexican populations (North Lacandonians, South Lacandonians, Tepehuanos, and Yaquis) were genotyped for two SNPs (LTA+252A>G and TNFA-308G>A) and four microsatellites (TNFa, d, e, and f), to analyze the genetic substructure of the Mexican population. Allele and haplotype frequencies, linkage disequilibrium (LD), and interpopulation genetic relationships were calculated. There was significant LD along almost all of the TNF block but the lowest D' values were observed for the TNFf-TNFd pair. Mestizos showed higher allele and haplotype diversity than did natives. The genetic differentiation level was reduced among Mestizos; however, a slightly, but significant genetic substructure was observed between northern and southern Mexican Mestizos. Among the Amerindian populations, the genetic differentiation level was significantly elevated, particularly in both North and South Lacandonians. Furthermore, among Southern Lacandonians, inhabitants of Lacanja town were the most differentiated from all the Mexicans analyzed. The data presented here will serve as a reference for further population and epidemiological studies including these TNF polymorphisms in the Mexican population.

XV-2c/KM19 haplotypes analysis of cystic fibrosis patients from western Mexico.

The analysis of polymorphic markers within or closely linked to the cystic fibrosis transmembrane regulator (CFTR) gene is useful as a molecular tool for carrier detection of known and unknown mutations. To establish the association between mutations in the CFTR gene in western Mexican cystic fibrosis (CF) patients, the distribution of XV2c/KM19 haplotypes was analyzed by PCR and restriction enzyme digestion in 384 chromosomes from 74 CF patients, their unaffected parents, and normal subjects. The haplotype analysis revealed that haplotype B was present in 71.9% of CF chromosomes compared to 0% of non-CF chromosomes. The F508del and G542X mutations were strongly associated with haplotype B (96.7% and 100% of chromosomes, respectively). The haplotype distribution of the CF chromosomes carrying other CFTR mutations had a more heterogeneous background. Our results show that haplotype B is associated with CFTR mutations. Therefore, haplotype analysis is a suitable alternate strategy for screening CF patients with a heterogeneous clinical picture from populations with a high molecular heterogeneity where carrier detection programs are not available. In addition, it may be a helpful diagnostic tool for genetic counseling and carrier detection in the relatives of CF patients and in couples who are planning to have children.

Congo red effect on cyst viability and cell wall structure of encysting. Entamoeba invadens.

BACKGROUND: The cell wall of Entamoeba invadens cysts is composed of chitin microfibrils as the main structural component. It has been demonstrated in yeast that the chitin cell wall assembly is altered by dyes such as Congo red (CR) and Calcofluor. METHODS: The purpose of this work was to study the cell wall assembly under the effect of CR dye on encysting E. invadens by means of light and electron microscopy, after the amebas were subjected to the effect of 100-2,000 micrograms CR/mL. Experiments were performed either in BI-S-33 or in mLG media. RESULTS: Trophozoite growth was not inhibited by 100-1,000 micrograms/mL CR after 8 days of incubation in BI-S-33 medium. However, low levels of growth were observed with 2,000 micrograms/mL of dye. No significant differences in morphologically viable (hyaline) cyst production occurred after 24-48 h, when 100 micrograms CR/mL was used, while the highest concentration of CR (2,000 micrograms/mL) resulted in a significant decrease of hyaline cyst yield; dead cysts prevailed in cultures, particularly at 72 h of CR treatment. Differentiation of amebas incubated in the presence of 500-2,000 micrograms/mL CR produced abnormal chitin deposits, rendering irregularly thick or double cell walls, as shown by transmission and scanning electron microscopy. Cyst cultures obtained under 100 micrograms/mL CR produced as many trophozoites as did the control when they were incubated in BI-S-33, but only low numbers of trophozoites were found in culture cysts obtained under higher CR doses. CONCLUSION: Our results suggest that CR affects E. invadens encystment, alters the cell wall formation, and also affects the cyst viability.

Simultaneous growth and mass encystation of Entamoeba invadens under axenic conditions.

Encystation of Entamoeba invadens IP-1 strain trophozoites was induced in low glucose medium (LG). The numbers of trophozoites, cysts and nuclei per cyst were determined; excystation of detergent-resistant axenic cysts was induced in both BI-S-33 and LG media. It was found that after 48 and 72 h of incubation in LG, cyst production was higher than trophozoites inoculated, 90 and 65% of those cysts being morphologically viable, respectively, as differentiation proceeded cysts became tri- and tetranucleated.E. invadens cysts were able to excyst either in BI-S-33 or LG media. There were no differences in growth kinetics when amebic cultures from cysts excysted in BI-S-33 were compared with parent strain. On the contrary, lower yields of trophozoites were achieved with amebas excysted and further cultured in LG medium, but they were able to grow and simultaneously undergo mass encystation. This, as well as other evidence, suggests that E. invadens trophozoites are able to modulate their physiology according to the nutrients and other factors available in the medium, in order to accomplish, growth, encystation or simultaneous growth and mass encystation. Induction of life cycle of pathogenic amebas under axenic conditions can provide answers to inhibit encystment and/or excystment.