1236 C/T and 3435 C/T polymorphisms of the ABCB1 gene in Mexican breast cancer patients.

MDR1, which is encoded by the ABCB1 gene, is involved in multidrug resistance (hydrophobic), as well as the elimination of xenotoxic agents. The association between ABCB1 gene polymorphisms and breast cancer risk in different populations has been described previously; however, the results have been inconclusive. In this study, we examined the association between polymorphisms 3435 C/T and 1236 C/T in the ABCB1 gene and breast cancer development in Mexican women according to their menopausal status and molecular classification. Molecular subtypes as well as allele and genotype frequencies were analyzed. A total of 248 women with initial breast cancer diagnosis and 180 ethnically matched, healthy, unrelated individuals were enrolled. Polymerase chain reaction-restriction fragment length polymorphism was performed to detect polymorphisms 3435 C/T and 1236 C/T in the ABCB1 gene. Premenopausal T allele carriers of the 3435 C/T polymorphism showed a 2-fold increased risk of breast cancer with respect to the reference and postmenopausal groups, as well as triple-negative expression regarding the luminal A/B molecular subrogated subtypes. In contrast, the CT genotype of the 1236 polymorphism was a protective factor against breast cancer. We conclude that the T allele carrier of the 3435 C/T polymorphism in the ABCB1 gene in combination with an estrogen receptor-negative status may be an important risk factor for breast cancer development in premenopausal women.

Association between polymorphisms in the thymidylate synthase gene and risk of breast cancer in a Mexican population.

Breast cancer (BC) is the leading cause of cancer-related deaths among women in Mexico. Two single-nucleotide polymorphisms (SNPs) in the thymidylate synthase (TS) gene, the 28-base pair (bp) tandem repeat in the TS 5'-untranslated enhanced region (TSER) and the 6-bp insertion/deletion in the TS 3'-untranslated region (TS 3'-UTR), increase the rate of misincorporation of uridylate into DNA and may lead to chromosomal damage. We examined the association between these polymorphisms and BC risk in Mexican women according to menopause status. Mexican patients with initial BC diagnosis (N = 230) and 145 individuals from a reference general population group (RGP) were included. For statistical analysis, the BC group was divided into pre- and post-menopause groups (PRE and POST groups, respectively). We analyzed both TS polymorphisms (TSER and TS 3'-UTR) using polymerase chain reaction. Finetti analysis was used to evaluate inter-and intra-group differences. The results showed a high frequency for the 3R and ins6 alleles in the BC, RGP, PRE, and POST groups. No significant differences were observed for the TS and TSER genotype and allele frequency distributions between groups. We found that the TSER and TS 3'-UTR SNPs are not associated with BC risk in Mexican patients.

Significance of linkage disequilibrium heterogeneous patterns in the 21q22.3 region for mapping 21 trisomy individuals.

Recombination patterns can be indirectly inferred by means of linkage disequilibrium (LD) estimates, since LD is negatively correlated with genetic distance. However, LD does not necessarily have absolute correspondence with genetic distance. We estimated LD at 5 loci located in the 21q22.3 region. These STRs (D21S1440, D21S168, D21S1260, D21S1446, and D21S1411) covered 8.81 Mb of the 21q22.3 region. They were genotyped by conventional PCR. Similar size samples previously validated by sequencing were used as a genotyping control. Three hundred and sixty-nine individuals (62 families) living in Guadalajara, Mexico, were included. As an inclusion criterion, each family had a positive paternity test by autosomal markers for the CODIS core loci. Two hundred and thirty phase known haplotypes were identified by familial segregation. Only those haplotypes whose frequency was higher than 4% were taken into account for LD estimation, expressed as Lewontin's D' coefficient and Bonferroni's correction P values. For all 5 loci, the genetic distributions were in agreement with Hardy-Weinberg expectations. Heterozygosity and haplotype diversity were ≥ 0.69 and 99.58%, respectively. D21S1440-D21S168 (4.51 cM) and D21S1446-D21S1411 (4.58 cM) marker haplotype frequencies were significantly different from those expected by random distribution. The remaining haplotypes, including those with minimal inter-distance (D21S1260-D21S1446, 1.44 Mb), did not show LD. The 5 STRs at the 21q22.3 region in this Mexican population showed a non-homogeneous LD pattern, which demonstrates that recombination or linkage should not be assumed solely on the basis of genetic distance.

Influence of apple cultivars on inactivation of different strains of Escherichia coli O157:H7 in apple cider by UV irradiation.

This study examined the effect of different apple cultivars upon the UV inactivation of Escherichia coli O157:H7 strains within unfiltered apple cider. Apple cider was prepared from eight different apple cultivars, inoculated with approximately 10(6) to 10(7) CFU of three strains of E. coli O157:H7 per ml (933, ATCC 43889, and ATCC 43895), and exposed to 14 mJ of UV irradiation per cm(2). Bacterial populations for treated and untreated samples were then enumerated by using nonselective media. E. coli O157:H7 ATCC 43889 showed the most sensitivity to this disinfection process with an average 6.63-log reduction compared to an average log reduction of 5.93 for both strains 933 and ATCC 43895. The highest log reduction seen, 7.19, occurred for strain ATCC 43889 in Rome cider. The same cider produced the lowest log reductions: 5.33 and 5.25 for strains 933 and ATCC 43895, respectively. Among the apple cultivars, an average log reduction range of 5.78 (Red Delicious) to 6.74 (Empire) was observed, with two statistically significant (alpha < or = 0.05) log reduction groups represented. Within the paired cultivar-strain analysis, five of eight ciders showed statistically significant (alpha < or = 0.05) differences in at least two of the E. coli strains used. Comparison of log reductions among the E. coli strains to the cider parameters of (o)Brix, pH, and malic acid content failed to show any statistically significant relationship (R(2) > or = 0.95). However, the results of this study indicate that regardless of the apple cultivar used, a minimum 5-log reduction is achieved for all of the strains of E. coli O157:H7 tested.

Modeling of Escherichia coli inactivation by UV irradiation at different pH values in apple cider.

This study examined the effects and interactions of UV light dose (1,800 to 20,331 microJ/cm2) and apple cider pH (2.99 to 4.41) on the inactivation of Escherichia coli ATCC 25922, a surrogate for E. coli O157:H7. A predictive model was developed to relate the log reduction factor of E. coli ATCC 25922 to the UV dose. Bacterial populations for treated and untreated samples were enumerated with the use of nonselective media. The results revealed that UV dose was highly significant in the inactivation of E. coli, whereas pH showed no significant effect at higher UV doses. Doses of 6,500 microJ/cm2 or more were sufficient to achieve a greater than 5-log reduction of E. coli. Experimental inactivation data were fitted adequately by a logistic regression model. UV irradiation is an attractive alternative to conventional methods for reducing bacteria in unpasteurized apple cider.