Twin seasonality in a rural Catalonian population

The seasonality of twinning in the Spanish populations has not been studied until now. Differences between seasonal distribution of the twin conceptions and those of the single births have been observed in other populations. The aim of this work is to explore the frequency of twinning in a rural population from Catalonia during the nineteenth century, as well as the seasonality patterns characterizing each of the twinning types. Data corresponding to all births recorded at Tortosa (South Catalonia) from 1801 to 1900 have been analyzed in order to study the twinning distribution. The distribution of the moving averages of the monthly rates of twins shows a peak in autumn. Twinning distribution differs from the total births' distribution in Tortosa. This fact is very clear in the case of unlike-sexed twins that have their greater incidence in the last quarter of the year, while the total maternities have their peak in the first one.     

Stridulation variability and morphology: an examination in dung beetles of the genus<Emphasis Type="Italic"> Trypocopris</Emphasis> (Coleoptera,Geotrupidae)

Distress signals produced by dung beetles of the genus Trypocopris (Coleoptera, Geotrupidae) were analysed to test whether interspecific and intraspecific acoustic variability are species- and subspecies-specific and to ascertain to what extent bioacoustic parameters depend upon the morphology of the stridulatory organs (pars stridens). Bioacoustic analyses showed that the three species were clearly differentiated, despite the fact that disturbance stridulations presented the same stereotyped spectrographic pattern. Within each species, most of the subspecies and populations considered were also bioacoustically distinguishable. Subspecies and populations within each species were differentiated with regard to body size and stridulatory organ, and the length of the pars stridens was positively correlated with the width of the coxa, in turn positively correlated with body size. A few spectrographic measures were significantly constrained by the morphology of the stridulatory apparatus; in particular the duration of sound emission was positively correlated with the length of the apparatus and the sub-pulse rate was negatively related to the distance between two consecutive crests. For T. pyrenaeus, with the largest number of populations sampled, there was no significant correlation between morphological and spectrographic distances, but there were significant positive correlations between morphological and geographical distances and between morphological and genetic distances. It is hypothesized that genetic differentiation might directly affect variability of the stridulatory apparata which would also be indirectly influenced and constrained by external morphological traits (like the width of the coxa and body size). Stridulatory organs, in turn, would affect the ways a few stridulatory traits (especially the temporal ones) change in time and space.     

Neighboring-group participation in benzylidene acetal ring-opening of a 2-cyano-2-deoxypyranoside derivative by diethylaluminum cyanide

The oxirane ring-opening of an anhydro sugar with diethylaluminum cyanide (Et(2)AlCN) is a direct approach for obtaining a cyano derivative. Methyl 2,3-anhydro-4,6-O-benzylidene-alpha-D-allopyranoside showed anomalous chemical behavior when treated with Et(2)AlCN. The reaction afforded the corresponding beta-cyanohydrin as the minor component from a mixture of compounds resulting from the benzylidene acetal ring-opening caused by the attack of ethyl or cyano groups.     

Genetic analysis of rabies virus isolates in the Philippines

To determine the genetic characteristics of the rabies virus in the Philippines, 59 rabies virus isolates were obtained from domestic rabid dogs and their partial nucleotide sequences of nucleoprotein (N) gene were compared. Based on comparison with reported sequences, phylogenetic analysis revealed that all isolates from the Philippines had close genetic relations and formed two subgroups. The Philippines isolates belonged to a different lineage from other Asian isolates but were closer to them than to terrestrial isolates and laboratory strains. Several specific nucleotide and amino acid substitutions were observed among the Philippines isolates. Our results suggest that rabies viruses in the Philippines might have a characteristic evolution.     

In vitro and in vivo assays of 3,5-disubstituted-tetrahydro-2H-1,3,5-thiadiazin-2-thione derivatives against Trypanosoma cruzi

Cytotoxicity assays of 24 new 3,5-disubstituted-tetrahydro-2H-1,3,5-thiadiazin-2-thione derivatives were performed. The 17 compounds with higher anti-epimastigote activity and lower cytotoxicity were, thereafter, screened against amastigote of Trypanosoma cruzi. Out of these 17 derivatives S-2d was selected to be assayed in vivo, because of its remarkable trypanocidal properties. To determine toxicity against J774 macrophages, a method based on quantification of cell damage, after 24 h, was used. Cell respiration, an indicator of cell viability, was assessed by the reduction of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] to formazan. Anti-amastigote activity was estimated after 48 h by microscopic counts of May Grünwald-Giemsa-stained monolayers. Nifurtimox and benznidazole were used as reference drugs. For the in vivo experiences, mice were infected with 10(4) blood trypomastigotes and then treated during 15 days with S-2d or nifurtimox by oral route. All of the compounds were highly toxic at 100 micro g/ml for macrophages and a few of them maintained this cytotoxicity even at 10 microg/ml. Of the derivatives assayed against amastigotes 3k and S-2d showed an interesting activity, that was held even at 1microg/ml. It is demonstrated that the high anti-epimastigote activity previously reported is mainly due to the non-specific toxicity of these compounds. In vivo assays assessed a reduction of parasitemia after administration of S-2d to infected mice.     

Micropatterned surfaces for the control of endothelial cell behaviour

Micropatterned materials were synthesised by photoimmobilising the sulphated hyaluronic acid, adequately functionalised with a photoreactive moiety, on glass substrates. Four different patterns (10, 25, 50 and 100 microns) were obtained. The spectroscopic and microscopic analysis of the microstructured surfaces revealed that the photoimmobilisation process was successful, demonstrating that the photomask was well reproduced on the sample surface. Analysis of endothelial cell behaviour on these micropatterned materials was performed in terms of adhesion, locomotion and orientation. Decreasing the stripe dimensions a more fusiform shape of the adhered endothelial cells was observed. At the same time the cell locomotion and orientation were increased. Furthermore, a photoimmobilisation of stripes of HyalS (10 and 100 microns) was performed on a continuous HyalS layer, in turn immobilised on glass substrate. Being excluded a different chemistry between the stripe and the substrate, the influence of topography on the behaviour of endothelia cells was thus envisaged.     

Fibrinogen conformation and platelet reactivity in relation to material-blood interaction: effect of stress hormones

The performance of many biomaterials in hemocompatibility tests is altered when blood is drawn from stressed subjects. A salient physiological response during stress is one in which hormones are released into plasma by the hypothalamo-pituitary-adrenal axis. We investigated the influence of basal and stress levels of epinephrine and beta-endorphin on the conformation of fibrinogen (Fbg), both in saline solution (under physiological conditions) and after its adsorption to polyethylene (PE), by FT-IR spectroscopy. Moreover, as Fbg is one of the major mediators of platelet adhesion, the behavior of platelets in contact with PE was also evaluated as a function of the two different hormone concentrations. Epinephrine was found to affect Fbg conformation and to increase platelet adhesion to PE at stress level. Basal and stress levels of beta-endorphin did not significantly affect the Fbg conformation and only induced adhesion of isolated platelets to the PE surface. A direct relationship was therefore found between Fbg conformation and platelet behavior. The response of platelets was affected by the stress status of donors through the influence of epinephrine on Fbg conformation.     

Bayesian analysis for nonlinear regression model under skewed errors,with application in growth curves

We have considered a Bayesian approach for the nonlinear regression model by replacing the normal distribution on the error term by some skewed distributions, which account for both skewness and heavy tails or skewness alone. The type of data considered in this paper concerns repeated measurements taken in time on a set of individuals. Such multiple observations on the same individual generally produce serially correlated outcomes. Thus, additionally, our model does allow for a correlation between observations made from the same individual. We have illustrated the procedure using a data set to study the growth curves of a clinic measurement of a group of pregnant women from an obstetrics clinic in Santiago, Chile. Parameter estimation and prediction were carried out using appropriate posterior simulation schemes based in Markov Chain Monte Carlo methods. Besides the deviance information criterion (DIC) and the conditional predictive ordinate (CPO), we suggest the use of proper scoring rules based on the posterior predictive distribution for comparing models. For our data set, all these criteria chose the skew‐t model as the best model for the errors. These DIC and CPO criteria are also validated, for the model proposed here, through a simulation study. As a conclusion of this study, the DIC criterion is not trustful for this kind of complex model.