Projecting the effectiveness of RotaTeq® against rotavirus-related hospitalisations in Brazil

RotaTeq? (Merck & Company, Inc, Whitehouse Station, NJ, USA) is an oral pentavalent rotavirus vaccine (RV5) that has shown high and consistent efficacy in preventing rotavirus gastroenteritis (RGE) in randomised clinical trials previously conducted in industrialised countries with high medical care resources. To date, the efficacy and effectiveness data for RV5 are available in some Latin American countries, but not Brazil. In this analysis, we projected the effectiveness of RV5 in terms of the percentage reduction in RGE-related hospitalisations among children less than five years of age in four regions of Brazil, using a previously validated mathematical model. The model inputs included hospital-based rotavirus surveillance data from Goiania, Porto Alegre, Salvador and S?o Paulo from 2005-2006, which provided the proportions of rotavirus attributable to serotypes G1, G2, G3, G4 and G9, and published rotavirus serotype-specific efficacy from the Rotavirus Efficacy and Safety Trial. The model projected an overall percentage reduction of 93% in RGE-related hospitalisations, with an estimated annual reduction in RGE-related hospitalisations between 42,991-77,383 in the four combined regions of Brazil. These results suggest that RV5 could substantially prevent RGE-related hospitalisations in Brazil.     

Strong male/male competition allows for nonchoosy females: high levels of polygynandry in a territorial frog with paternal care

Our knowledge about genetic mating systems and the underlying causes for and consequences of variation in reproductive success has substantially improved in recent years. When linked to longitudinal population studies, cross-generational pedigrees across wild populations can help answer a wide suite of questions in ecology and evolutionary biology. We used microsatellite markers and exhaustive sampling of two successive adult generations to obtain population-wide estimates of individual reproductive output of males and females in a natural population of the Neotropical frog Allobates femoralis (Aromobatidae), a pan-Amazonian species that features prolonged iteroparous breeding, male territoriality and male parental care. Parentage analysis revealed a polygynandrous mating system in which high proportions of males (35.5%) and females (56.0%) produced progeny that survived until adulthood. Despite contrasting reproductive strategies, successfully reproducing males and females had similar numbers of mating partners that sired the adult progeny (both sexes: median 2; range 1-6); the numbers of their offspring that reached adulthood were also similar (both sexes: median 2; range 1-8). Measures of reproductive skew indicate selection on males only for their opportunity to breed. Reproductive success was significantly higher in territorial than in nonterritorial males, but unrelated to territory size in males or to body size in both sexes. We hypothesize that female polyandry in this species has evolved because of enhanced offspring survival when paternal care is allocated to multiple partners.     

Modeling parasitism rate and parasitism risk: an illustration using a colonially nesting songbird, the red-winged blackbird Agelaius phoeniceus

Ornithologists interested in the drivers of nest success and brood parasitism benefit from the development of new analytical approaches. One example is the development of so-called "log exposure" models for analyzing nest success. However, analyses of brood parasitism data have not kept pace with developments in nest success analyses. The standard approach uses logistic regression which does not account for multiple parasitism events, nor does it prevent bias from using observed proportions of parasitized nests. Likewise, logistic regression analyses do not capture fine scale temporal variation in parasitism. At first glance, it might be tempting to apply log exposure models to parasitism data, but the process of parasitism is inherently different from the process of nest predation. We modeled daily parasitism rate as a Poisson process, which allowed us to correct potential biases in parasitism rate. We were also able to use our estimated parasitism rate to model parasitism risk as the probability of one or more parasitism events. We applied this model to red-winged blackbird Agelaius phoeniceus nesting colonies subject to parasitism by brown-headed cowbirds Molothrus ater . Our approach allowed us to model parasitism using a wider rage of covariates, especially functions of time. We found strong support for models combining temporal fluctuations in parasitism rate and nest-site characteristics. Similarly, we found that our annual predicted parasitism risk was lower on average than the risk estimated from observed parasitism levels. Our approach improves upon traditional logistic regression analyses and opens the door for more mechanistic modeling of the process of parasitism.     

A polarimetric study of the reaction of bis(L-serinato)copper(II) with formaldehyde

Polarimetric data have shown that the base-catalyzed reaction of bis(L-serinato)copper(II) with excess formaldehyde proceeds via the initial dissociation of the proton on the nitrogen atom of the amino acid chelate. A bis(oxazolidine)copper(II) complex appears as an intermediate but this species is not detected polarimetrically at 50°C and above.     

The differential effect of disulfiram on lipoxygenases from Glycine max

A kinetic analysis of the effect of disulfiram on the isoenzymes of lipoxygenase from soybean has been carried out. The compound is an effective inhibitor of type-2 isoenzymes but has no effect on the type-1 isoenzyme under the conditions employed in this study. The inhibitory effect is reversible and therefore does not result from covalent modification of the enzyme. The inhibition is manifest as a prolongation of the lag phase commonly seen in progress curves for lipoxygenases rather than as a reduction of the catalysed rate. A variety of structurally related and unrelated compounds have been investigated to identify the nature of the inhibitory effect. The antioxidant properties of disulfiram account for its ability to inhibit type-2 lipoxygenases. The inhibitory effect of antioxidants on type-2 lipoxygenase is only partly reversed when product hydroperoxide is included in the incubation mixture. These observations support the conclusion that free radical intermediates are integral to the catalytic mechanism of type-2 lipoxygenases.     

Dynamics of dense electronegative low density lipoproteins and their preferential association with lipoprotein phospholipase A(2)

Small, dense, electronegative low density lipoprotein [LDL(-)] is increased in patients with familial hypercholesterolemia and diabetes, populations at increased risk for coronary artery disease. It is present to a lesser extent in normolipidemic subjects. The mechanistic link between small, dense LDL(-) and atherogenesis is not known. To begin to address this, we studied the composition and dynamics of small, dense LDL(-) from normolipidemic subjects. NEFA levels, which correlate with triglyceride content, are quantitatively linked to LDL electronegativity. Oxidized LDL is not specific to small, dense LDL(-) or lipoprotein [a] (i.e., abnormal lipoprotein). Apolipoprotein C-III is excluded from the most abundant LDL (i.e., that of intermediate density: 1.034 < d < 1.050 g/ml) but associated with both small and large LDL(-). In contrast, lipoprotein-associated phospholipase A(2) (LpPLA(2)) is highly enriched only in small, dense LDL(-). The association of LpPLA(2) with LDL may occur through amphipathic helical domains that are displaced from the LDL surface by contraction of the neutral lipid core.     

Optimized variants of the cold shock protein from in vitro selection: structural basis of their high thermostability

The bacterial cold shock proteins (Csp) are widely used as models for the experimental and computational analysis of protein stability. In a previous study, in vitro evolution was employed to identify strongly stabilizing mutations in Bs-CspB from Bacillus subtilis. The best variant found by this approach contained the mutations M1R, E3K and K65I, which raised the midpoint of thermal unfolding of Bs-CspB from 53.8 degrees C to 83.7 degrees C, and increased the Gibbs free energy of stabilization by 20.9 kJ mol(-1). Another selected variant with the two mutations A46K and S48R was stabilized by 11.1 kJ mol(-1). To elucidate the molecular basis of these stabilizations, we determined the crystal structures of these two Bs-CspB variants. The mutated residues are generally well ordered and provide additional stabilizing interactions, such as charge interactions, additional hydrogen bonds and improved side-chain packing. Several mutations improve the electrostatic interactions, either by the removal of unfavorable charges (E3K) or by compensating their destabilizing interactions (A46K, S48R). The stabilizing mutations are clustered at a contiguous surface area of Bs-CspB, which apparently is critically important for the stability of the beta-barrel structure but not well optimized in the wild-type protein.     

The solution and crystal structures of a module pair from the Staphylococcus aureus-binding site of human fibronectin--a tale with a twist

An important goal of structural studies of modular proteins is to determine the inter-module orientation, which often influences biological function. The N-terminal domain of human fibronectin (Fn) is composed of a string of five type 1 modules (F1). Despite their small size, to date F1 modules have proved intractable to X-ray structure solution, although there are several NMR structures available. Here, we present the first structures (two X-ray models and an NMR-derived model) of the (2)F1(3)F1 module pair, which forms part of the binding site for Fn-binding proteins from pathogenic bacteria. The crystallographic structure determination was aided by the novel technique of UV radiation damage-induced phasing. The individual module structures are very similar in all three models. In the NMR structure and one of the X-ray structures, a similar but smaller interdomain interface than that observed previously for (4)F1(5)F1 is seen. The other X-ray structure has a different interdomain orientation. This work underlines the benefits of combining X-ray and NMR data in the studies of multi-domain proteins.