Host-feeding preference of the mosquito, Culex quinquefasciatus, in Yucatan State, Mexico.

Studies were conducted to determine the host-feeding preference of Culex quinquefasciatus Say (Diptera: Culicidae) in relation to the availability of human and domestic animals in the city of Merida, Yucatan State, Mexico. Mosquitoes were collected in the backyards of houses using resting wooden boxes. Collections were made five times per week from January to December 2005. DNA was extracted from engorged females and tested by PCR using universal avian- and mammalian-specific primers. DNA extracted from avian-derived blood was further analyzed by PCR using primers that differentiate among the birds of three avian orders: Passeriformes, Columbiformes and Galliformes. PCR products obtained from mammalian-derived blood were subjected to restriction enzyme digestion to differentiate between human-, dog-, cat-, pig-, and horse-derived blood meals. Overall, 82% of engorged mosquitoes had fed on birds, and 18% had fed on mammals. The most frequent vertebrate hosts were Galliformes (47.1%), Passeriformes (23.8%), Columbiformes (11.2%) birds, and dogs (8.8%). The overall human blood index was 6.7%. The overall forage ratio for humans was 0.1, indicating that humans were not a preferred host for Cx. quinquefasciatus in Merida.

Folate, homocysteine, interleukin-6, and tumor necrosis factor alfa levels, but not the methylenetetrahydrofolate reductase C677T polymorphism, are risk factors for schizophrenia.

The methylenetetrahydrofolate reductase (MTHFR) C677T mutation has been associated to high homocysteine levels and schizophrenia. Since cytokines are altered in schizophrenia and increments of homocysteine could promote an inflammatory response, it was investigated whether interleukin-6 (IL-6) and tumor necrosis factor alfa (TNFalpha) levels are modulated by the MTHFR genotype. Serum levels of TNFalpha, IL-6, B(12), homocysteine, folate and red blood cell (RBC) folate as well as the MTHFR genotype were determined in a group of schizophrenic patients and compared to those of a control group. RBC folate levels were reduced and homocysteine and the two cytokines' concentrations were elevated in all patients as compared to controls. RBC folate in both heterozygous (CT) and homozygous (TT) patients was significantly different to that of their respective control groups. Homocysteine levels found in patients were significantly higher than those found in controls, only in individuals carrying the TT genotype. Cytokine levels were augmented in the group of patients irrespective of the genotype, and significant differences were found in all cases, except for TNFalpha levels in those subjects carrying the CC genotype. After adjusting for sex, low levels of RBC folate, high levels of homocysteine, both medium and high levels of TNFalpha and high IL-6 levels were associated with schizophrenia. MTHFR genotype was not a risk factor for developing the disease, although a larger sample is required to confirm this finding.

Las plantas del Nuevo Mundo y su amplísima utilización en la Medicina tradicional desde los tiempos precolombinos / The plants of the New World and their wide use in traditional Medicine since pre-Columbian times

Nos complace presentar en este número, el primero del Volumen 20, un artículo original que demuestra una actividad larvicida de plantas americanas contra Aedes aegypti (transmisor del dengue), lo que representa una herramienta alternativa de elevado impacto dentro de las medidas para el control y el manejo integrado de vectores.

A mutation in the 5,10-methylenetetrahydrofolate reductase gene is not associated with preeclampsia in women of southeast Mexico.

BACKGROUND: We investigated the possible association between C677T-5,10-methylenetetrahydrofolate (MTHFR) polymorphism and preeclampsia in women from the Yucatan Peninsula in Mexico. METHODS: We performed a comparative study among three groups of subjects: 148 preeclamptic women; 177 women with normal pregnancies, and 313 healthy volunteers as control group. All subjects were genotyped for C677T polymorphism in MTHFR gene by PCR amplification and digestion of the product with Hinf I restriction enzyme. Genotypic and allelic frequencies were compared between affected women (preeclamptic) and nonaffected groups to determine the association using Fisher exact test. Odds ratios (ORs) were also calculated to obtain estimation of relative risk (RR) for developing preeclampsia. RESULTS: Statistical analysis of intergroup comparisons among preeclamptic women, women with normal pregnancies, and control group showed no statistically significant differences for any genotype or for T allele (p >0.05). CONCLUSIONS: Our results suggest that C677T-MTHFR polymorphism is not an associated risk factor for developing preeclampsia in southeast Mexico. Results also confirmed high prevalence of C677T mutation in Mexico.