Functions of T cells in asthma: more than just T(H)2 cells

Asthma has been considered a T helper 2 (T(H)2) cell-associated inflammatory disease, and T(H)2-type cytokines, such as interleukin-4 (IL-4), IL-5 and IL-13, are thought to drive the disease pathology in patients. Although atopic asthma has a substantial T(H)2 cell component, the disease is notoriously heterogeneous, and recent evidence has suggested that other T cells also contribute to the development of asthma. Here, we discuss the roles of different T cell subsets in the allergic lung, consider how each subset can contribute to the development of allergic pathology and evaluate how we might manipulate these cells for new asthma therapies.     

Larvae of related Diptera species from thermally contrasting habitats exhibit continuous up-regulation of heat shock proteins and high thermotolerance

A population of Stratiomys japonica, a species belonging to the family Stratiomyidae (Diptera), common name ‘soldier flies’, occurs in a hot volcanic spring, which is apparently among the most inhospitable environments for animals because of chemical and thermal conditions. Larvae of this species, which naturally often experience temperatures more than 40 °C, have constitutively high concentrations of the normally inducible heat-shock protein Hsp70, but very low level of corresponding mRNA. Larvae of three other species of the same family, Stratiomys singularior, Nemotelus bipunctatus and Oxycera pardalina, are confined to different type semi-aquatic habitats with contrasting thermal regime. However, all of them shared the same pattern of Hsp70 expression. Interestingly, heat-shock treatment of S. japonica larvae activates heat-shock factor and significantly induces Hsp70 synthesis, whereas larvae of O. pardalina, a species from constant cold environment, produce significantly less Hsp70 in response to heat shock. Adults of the four species also exhibit lower, but detectable levels of Hsp70 without heat shock. Larvae of all species studied have very high tolerance to temperature stress in comparison with other Diptera species investigated, probably representing an inherent adaptive feature of all Stratiomyidae enabling successful colonization of highly variable and extreme habitats.     

Two Carotenoid Oxygenases Contribute to Mammalian Provitamin A Metabolism

Mammalian genomes encode two provitamin A-converting enzymes as follows: the β-carotene-15,15′-oxygenase (BCO1) and the β-carotene-9′,10′-oxygenase (BCO2). Symmetric cleavage by BCO1 yields retinoids (β-15′-apocarotenoids, C₂₀), whereas eccentric cleavage by BCO2 produces long-chain (>C₂₀) apocarotenoids. Here, we used genetic and biochemical approaches to clarify the contribution of these enzymes to provitamin A metabolism. We subjected wild type, Bco1^−/−, Bco2^−/−, and Bco1^−/−Bco2^−/− double knock-out mice to a controlled diet providing β-carotene as the sole source for apocarotenoid production. This study revealed that BCO1 is critical for retinoid homeostasis. Genetic disruption of BCO1 resulted in β-carotene accumulation and vitamin A deficiency accompanied by a BCO2-dependent production of minor amounts of β-apo-10′-carotenol (APO10ol). We found that APO10ol can be esterified and transported by the same proteins as vitamin A but with a lower affinity and slower reaction kinetics. In wild type mice, APO10ol was converted to retinoids by BCO1. We also show that a stepwise cleavage by BCO2 and BCO1 with APO10ol as an intermediate could provide a mechanism to tailor asymmetric carotenoids such as β-cryptoxanthin for vitamin A production. In conclusion, our study provides evidence that mammals employ both carotenoid oxygenases to synthesize retinoids from provitamin A carotenoids.     

Hepatic Involvement in Pediatric Patients with Paracoccidioidomycosis: A Clinical and Laboratory Study

The liver is one of the organs most affected by paracoccidioidomycosis, a systemic mycosis endemic in some Latin American countries. The majority of articles focused on adult populations and failed to describe any detailed experience of liver abnormalities in pediatric patients. Therefore, the aim of this study was to describe the frequency and characteristics of liver involvement in children with paracoccidioidomycosis. This study comprised 102 patients less than 16 years of age (median 104.3 months) diagnosed with paracoccidioidomycosis from 1980 to 2010. Diagnosis was established by the identification of fungus. Forty-one patients had liver involvement. The main clinical features were generalized lymph node enlargement (39/41), weight loss (34/41) and fever 32/41). Approximately, one-third of the patients had jaundice. Patients with hepatic involvement were younger. A predominant elevation of canalicular enzymes occurred. There was a statistically significant difference in albumin (p < 0.001) and hemoglobin (p = 0.002) values between patients with and without liver involvement, and the lowest values were found in the former group. Cutoff levels of albumin (<3.05 g/dL) and hemoglobin (<9.2 g/dL) can be used to infer hepatic involvement. Hypoalbuminemia (median 2.4 g/dl) is more severe in patients with hepatic involvement and may indicate a worse liver function or complication of the disease (intestinal lymphangiectasia). Deaths (6) occurred only among patients with liver involvement. Particular clinical and laboratory characteristics are present in pediatric patients with hepatic involvement. Younger patients and those with severe hypoalbuminemia are more likely to present liver involvement by Paracoccidioides brasiliensis.     

Production of biodiesel by Burkholderia cepacia lipase as a function of process parameters

Despite the already established route of chemically catalyzed transesterification reaction in biodiesel production, due to some of its shortcomings, biocatalysts such as lipases present a vital alternative. Namely, it was noticed that one of the key shortcomings for the optimization of the enzyme catalyzed biodiesel synthesis process is the information on the lipase activity in the reaction mixture. In addition to making optimization difficult, it also makes it impossible to compare the results of the independent research. This article shows how lipase intended for use in biodiesel synthesis can be easily and accurately characterized and what is the enzyme concentration that enables achievement of the desired level of fatty acid methyl esters (FAME) in the final product mixture. Therefore, this study investigated the effect of two different activity loads of Burkholderia cepacia lipase on the biodiesel synthesis varying the pH and temperature optimal for lipase activity. The optimal lipase pH and temperature were determined by two different enzyme assays: spectrophotometric and titrimetric. The B. cepacia lipase pH optimum differentiated between assays, while the lipase optimally hydrolyzed substrates at 50°C. The analysis of FAME during 24 hr of biodiesel synthesis, at two different enzyme concentrations, pH 7, 8, and 10, and using two different buffers, revealed that the transesterification reaction at optimal pH, 1 hr reaction time and lipase activity load of 250 U per gram of reaction mixture was sufficient to produce more than 99% FAME.     

How Feeling Betrayed Affects Cooperation

For a population of interacting self-interested agents, we study how the average cooperation level is affected by some individuals'' feelings of being betrayed and guilt. We quantify these feelings as adjusted payoffs in asymmetric games, where for different emotions, the payoff matrix takes the structure of that of either a prisoner''s dilemma or a snowdrift game. Then we analyze the evolution of cooperation in a well-mixed population of agents, each of whom is associated with such a payoff matrix. At each time-step, an agent is randomly chosen from the population to update her strategy based on the myopic best-response update rule. According to the simulations, decreasing the feeling of being betrayed in a portion of agents does not necessarily increase the level of cooperation in the population. However, this resistance of the population against low-betrayal-level agents is effective only up to some extend that is explicitly determined by the payoff matrices and the number of agents associated with these matrices. Two other models are also considered where the betrayal factor of an agent fluctuates as a function of the number of cooperators and defectors that she encounters. Unstable behaviors are observed for the level of cooperation in these cases; however, we show that one can tune the parameters in the function to make the whole population become cooperative or defective.     

Native fibrin gel networks observed by 3D microscopy, permeation and turbidity

Native fully hydrated fibrin gels formed at different fibrinogen and thrombin concentrations and at different ionic strengths were studied by confocal laser 3D microscopy, liquid permeation and turbidity. The gels were found to be composed of straight rod-like fiber elements that often came together at denser nodes. In gels formed at high fibrinogen concentrations, or with high amounts of thrombin, the spaces between the fibers decreased, indicating a decrease of gel porosity. The fiber strands were also shorter. Gel porosity decreased dramatically in gels formed at the high ionic strengths. Shorter fibers were observed and fiber swelling occurred at ionic strengths above 0.24. Quantitative parameters for gel porosity, fiber mass/length ratio and diameter were also derived by liquid permeation and turbidometric analyses of the gels. Permeation analysis showed that gel porosity (measured as Ks) decreased in gels formed at higher fibrin and thrombin concentrations in agreement with the porosity observed by microscopy. The turbidometric analysis showed good agreement with the permeation data for gels formed at various thrombin concentrations, but supported the permeation data more poorly in gels formed at different fibrinogen concentrations, especially above 2.5 mg/ml. Turbidometric analysis showed that the fiber mass/length ratio and diameter decreased in gels formed at ionic strength up to 0.24, as was seen in the permeation study. However, at higher ionic strengths swelling of the fibers was suggested from the gel turbidity data and this was also indicated by microscopy. These findings are discussed in relation to previous hydrodynamic and electron microscopic studies of fibrin gels.     

A conserved coiled‐coil protein pair focuses the cytokinetic Z‐ring in Caulobacter crescentus

The cytoskeletal GTPase FtsZ assembles at midcell, recruits the division machinery and directs envelope invagination for bacterial cytokinesis. ZapA, a conserved FtsZ‐binding protein, promotes Z‐ring stability and efficient division through a mechanism that is not fully understood. Here, we investigated the function of ZapA in Caulobacter crescentus. We found that ZapA is encoded in an operon with a small coiled‐coil protein we named ZauP. ZapA and ZauP co‐localized at the division site and were each required for efficient division. ZapA interacted directly with both FtsZ and ZauP. Neither ZapA nor ZauP influenced FtsZ dynamics or bundling, in vitro, however. Z‐rings were diffuse in cells lacking zapA or zauP and, conversely, FtsZ was enriched at midcell in cells overproducing ZapA and ZauP. Additionally, FtsZ persisted at the poles longer when ZapA and ZauP were overproduced, and frequently colocalized with MipZ, a negative regulator of FtsZ polymerization. We propose that ZapA and ZauP promote efficient cytokinesis by stabilizing the midcell Z‐ring through a bundling‐independent mechanism. The zauPzapA operon is present in diverse Gram‐negative bacteria, indicating a common mechanism for Z‐ring assembly.