Chiral symmetry breaking induced by energy dissipation.

Spontaneous chiral symmetry breaking is observed in a wide variety of systems on very different scales, from the subatomic to the cosmological. Despite its generality and importance for a large number of applications, its origin is still a matter of debate. It has been shown that the existence of a difference between the energies of the intermediate states of optical enantiomers leads to disparate production rates and thus to symmetry breaking. However, it is still unclear why this occurs. We measured for the first time the optical rotation angle of NaClO3 enantiomeric crystals in solution during their formation and found that the amount of energy needed to induce the enantiomeric excess is exactly the same as the energy dissipated per mole of solid salt calculated from the entropy production obtained from the proposed model. The irreversible nature of the process leading to entropy production thus explains the chiral symmetry breaking in the salt crystals studied. The proposed method could be used to explain the formation of self-organised structures generated by self-assembly of enantiomers arising from chiral symmetry breaking, such as those emerging in the production of advanced materials and synthetic biological tissues.

Characterization of Gene Expression in the Rat Brainstem After Neonatal Hypoxic-Ischemic Injury and Antioxidant Treatment.

The perinatal brainstem is known to be very vulnerable to hypoxic-ischemic events which can lead to deafness, swallowing dysfunction, and defective respiratory control. The aim of the present work was to evaluate the potential neuroprotective effects of nicotine, melatonin, resveratrol, and docosahexaenoic acid on the expression of a panel of genes in the brainstem following hypoxic-ischemic damage. Quantitative PCR was used to examine gene expression 3 and 12 h after the damage, and immunohistochemistry was employed to evaluate neurons, astrocytes, and synaptic vesicles 24 h post insult. We found that the expression of some immediate-early genes, as well as that of inflammatory genes TNF-α, COX2, and caspase 3, was upregulated in response to the insult. Twenty-four hours after the damage, the percentage of NeuN and synaptophysin immunolabeled cells was found to be reduced while GFAP expression was upregulated. No differences were observed in ROS gene expression following treatments.

Epimastigogénesis de Trypanosoma cruzi: método para estudiar in vivo la transformación de tripomastigota en epimastigota / Trypanosoma cruzi epimastigogenesis: a method for studying Trypomastigote to epimastigote transformation in vivo

La epimastigogénesis de Trypanosoma cruzi ocurre naturalmente en el intestino del hospedador invertebrado. Se desconoce si los cambios morfológicos que ocurren durante la transformación de los tripomastigotas sanguíneos en epimastigotas son idénticos para diferentes aislados de T. cruzi. Aquí mostramos un método útil para estudiar los eventos que ocurren durante la epimastigogénesis, comparando parásitos de diferentes procedencias epidemiológicas. Se alimentaron artificialmente ninfas de V estadio de Rhodnius prolixus con una solución ad hoc conteniendo tripomastigotas tipo-sanguíneo y siguiendo los cambios morfológicos por 8 días. Los contenidos del intestino anterior de las ninfas se obtuvieron decapitando y comprimiendo el abdomen lo que permitió obtener rápidamente casi 100% del inóculo con cargas entre 1,9 y 8,9 × 106 tripomastigotas/ninfa. El número de parásitos por ninfa y los cambios morfológicos se determinaron por Microscopia de Contraste de Fases y coloración con Giemsa. Las ninfas ingirieron 7,4 veces su peso de solución infectante, con volúmenes entre 101 y 357 µL (229 ± 66 mg), 50% de esa ingesta se eliminó como orina durante las primeras 24 h. Los tripomastigotas se transformaron en formas redondeadas antes de evolucionar a epimastigotas, siguiendo cinéticas diferentes según el aislado. Proponemos esta metodología para estudiar rápida y cuantitativamente los eventos tempranos de la epimastigogénesis de T. cruzi in vivo.

Trypanosoma cruzi epimastigogenesis naturally occurs in the intestine of the invertebrate host. It is not known whether the morphological changes that occur during transformation of bloodstream trypomastigotes to epimastigotes are identical for different T. cruzi isolates. This research shows a useful method for studying the events that occur during epimastigogenesis, comparing parasites from epidemiological sources. Rhodnius prolixus V stage nymphs were fed artificially with an ad hoc solution containing blood-like trypomastigotes and the morphological changes were examined during eight days. Anterior intestinal contents were removed by decapitation and squeezing the abdomen of the nymphs, which permitted obtaining quickly almost 100% of the inoculate with loads between 1.9 and 8.9 × 106 trypomastigotes/nymph. The number of parasites per nymph and morphological changes were determined using phase microscopy with Giemsa staining. The nymphs ingested 7.4 times their weight of the infecting solution with volumes between 101 e 357 µL (229 ± 66 mg); 50% of the ingest was eliminated as urine during the first 24 hours. The trypomastigotes transformed to rounded forms before evolving into epimastigotes following different kinetics according to the isolate. This method is proposed for rapid, quantitative study of the early events of epimastigogenesis for T. cruzi in vivo.

Dental caries prevalence and tooth loss in chilean adult population: first national dental examination survey.

The purpose of this study was to assess the prevalence of dental caries, tooth loss, and risk factors among adult population of Chile. Furthermore, age, gender, and behavioural specific differences in caries prevalence and tooth loss were examined. A national stratified multistage probabilistic sample design in two-age cohorts was applied to the Chilean population. A sample of 1553 adults, comprising 1088 individuals aged 35-44 and 465 senior individuals aged 65-74, were examined. The DMFT was evaluated following WHO recommendations using diagnostic criteria of caries lesions into dentin. The data were analyzed by univariate and multivariate models using logistic regression analyses. Results showed a mean DMFT of 15.06 in the 35-44-year-old group and of 21.57 in the 65-74 group. Factors related to tooth loss in the 35-44 group through univariate logistic regression were depression (OR 1.9 CI 95% 1.26-2.85), education level <12 years (OR 2.24 CI 95% 1.31-3.73), personal income (OR 1.51 CI 95% 1.04-2.19), and familiar income (OR 2.05 CI 95% 1.34-3.13), and through multivariate logistic regression in the same age group were depression (OR 1.93 CI 95% 1.24-3.0), education level <12 years (OR 1.94 CI 95% 1.2-3.14), and familiar income (OR 1.71 CI 95% 1.09-2.68). Factors related to tooth loss in the 65-74-year-old group through univariate logistic regression were education level <12 years (OR 2.54 CI 95% 1.3-4.96) and personal income (OR 1.66 CI 95% 1.05-2.63), and for multivariate logistic regression in the same age group, it was education level <12 years (OR 2.51 CI 95% 1.21-5.18). In conclusion, adult population in Chile showed a high prevalence of dental caries and tooth loss, as age, education level, personal and familiar incomes, and depression are being the main risk factors.