Preliminary human health risk assessment of arsenic and fluoride in tap water from Zacatecas, México.

Zacatecas state is located in the central area of Mexico, where the underground water contains elevated quantities of natural arsenic and fluoride. In order to estimate health risk associated with human exposure to these pollutants, tap water samples from the southern-central region of the state were analyzed. Ninety percent of the samples exceeded the levels of arsenic established by the World Health Organization (WHO) of 0.01 mg/L and 43 % exceeded the limit established by the NOM-127-SSA1(1) of 0.025 mg/L. Forty-three percent of the samples had fluoride levels above the Mexican regulation limit of 1.5 mg/L (NOM-127-SSA1). We used WHO and EPA's health risk assessment method, we estimated 80 % of the inhabitants of sites studied could be exposed to arsenic levels higher than those recommended by EPA and the WHO, 22 % could be exposed to fluoride levels higher than those recommended by EPA, and 16 % of the local population may be in risk of suffering dental fluorosis.

Long-term exposure to particulate matter from air pollution alters airway ß-defensin-3 and -4 and cathelicidin host defense peptides production in a murine model.

Epidemiological studies have associated long-term exposure to environmental air pollution particulate matter (PM) with the development of diverse health problems. They include infectious respiratory diseases related to the deregulation of some innate immune response mechanisms, such as the host defense peptides' expression. Herein, we evaluated in BALB/c mice the effect of long-standing exposure (60 days) to urban-PM from the south of Mexico City, with aerodynamic diameters below 2.5 µm (PM2.5) and 10 µm (PM10) on the lung's gene expression and production of three host defense peptides (HDPs); murine beta-defensin-3, -4 (mBD-3, mBD-4) and cathelin-related antimicrobial peptide (CRAMP). We also evaluated mRNA levels of Il1b and Il10, two cytokines related to the expression of host defense peptides. Exposure to PM2.5 and PM10 differentially induced lung inflammation, being PM2.5, which caused higher inflammation levels, probably associated with a differential deposition on the airways, that facilitate the interaction with alveolar macrophages. Inflammation levels were associated with an early upregulation of the three HDPs assessed and an increment in Il1b mRNA levels. Interestingly, after 28 days of exposure, Il10 mRNA upregulation was observed and was associated with the downregulation of HDPs and Il1b mRNA levels. The upregulation of Il10 mRNA and suppression of HDPs might facilitate microbial colonization and the development of diseases associated with long-term exposure to PM.

The Cytocidal Spectrum of Bacillus thuringiensis Toxins: From Insects to Human Cancer Cells.

Bacillus thuringiensis (Bt) is a ubiquitous bacterium in soils, insect cadavers, phylloplane, water, and stored grain, that produces several proteins, each one toxic to different biological targets such as insects, nematodes, mites, protozoa, and mammalian cells. Most Bt toxins identify their particular target through the recognition of specific cell membrane receptors. Cry proteins are the best-known toxins from Bt and a great amount of research has been published. Cry are cytotoxic to insect larvae that affect important crops recognizing specific cell membrane receptors such as cadherin, aminopeptidase-N, and alkaline phosphatase. Furthermore, some Cry toxins such as Cry4A, Cry4B, and Cry11A act synergistically with Cyt toxins against dipteran larvae vectors of human disease. Research developed with Cry proteins revealed that these toxins also could kill human cancer cells through the interaction with specific receptors. Parasporins are a small group of patented toxins that may or may not have insecticidal activity. These proteins could kill a wide variety of mammalian cancer cells by recognizing specific membrane receptors, just like Cry toxins do. Surface layer proteins (SLP), unlike the other proteins produced by Bt, are also produced by most bacteria and archaebacteria. It was recently demonstrated that SLP produced by Bt could interact with membrane receptors of insect and human cancer cells to kill them. Cyt toxins have a structure that is mostly unrelated to Cry toxins; thereby, other mechanisms of action have been reported to them. These toxins affect mainly mosquitoes that are vectors of human diseases like Anopheles spp (malaria), Aedes spp (dengue, zika, and chikungunya), and Culex spp (Nile fever and Rift Valley fever), respectively. In addition to the Cry, Cyt, and parasporins toxins produced during spore formation as inclusion bodies, Bt strains also produce Vip (Vegetative insecticidal toxins) and Sip (Secreted insecticidal proteins) toxins with insecticidal activity during their vegetative growth phase.

Gender as a factor of susceptibility to infection in experimental hydatidosis.

We developed an experimental model of hydatidosis in BALB/c mice with six groups, a group of females and another group of males was infected with PSC of Echinococcus, granulosus. Another two groups were gonadectomised and infected with PSC. and another two groups were healthy controls. They were all bled and sacrificed after sixteen weeks post-infection. The cysts in the abdominal cavity were count, and samples were taken from liver. A microscopic study was made of the tissue around the cyst to evaluate the chronic inflammatory response. In addition the seric levels of estradiol and testosterone by means of radioimmunoassay (RIA) were determined. The results were that the females presented a greater number of cysts in liver than the males, in addition the levels to estradiol almost rose to the double in males and females after 16 weeks post-infection, and the testosterone diminished. The granulomatous response around the cysts was greater in the females than in the males. The gonadectomization affected the susceptibility to the infection in females, diminishing in number of hepatic cysts found. One concluded that the females are more susceptible to the infection by metacestode of E. granulosrus, than the males. The female displayed one better granulomatous answer than the males. Nevertheless this was not sufficient to eliminate the parasite or to inhibit its growth. The levels of estradiol and testosterone undergo an imbalance, observing that estradiol increased in chronic stages of the infection whereas the testosterone diminishes, which would indicate to us that probably the parasite causes hormonal imbalance in chronic stages, to be able to remain by long periods in its host.