A G‐CSF functionalized scaffold for stem cells seeding: a differentiating device for cardiac purposes

Myocardial infarction and its consequences represent one of the most demanding challenges in cell therapy and regenerative medicine. Transfer of skeletal myoblasts into decompensated hearts has been performed through intramyocardial injection. However, the achievements of both cardiomyocyte differentiation and precise integration of the injected cells into the myocardial wall, in order to augment synchronized contractility and avoid potentially life‐threatening alterations in the electrical conduction of the heart, still remain a major target to be pursued. Recently, granulocytes colony‐stimulating factor (G‐CSF) fuelled the interest of researchers for its direct effect on cardiomyocytes, inhibiting both apoptosis and remodelling in the failing heart and protecting from ventricular arrhythmias through the up‐regulation of connexin 43 (Cx43). We propose a tissue engineering approach concerning the fabrication of an electrospun cardiac graft functionalized with G‐CSF, in order to provide the correct signalling sequence to orientate myoblast differentiation and exert important systemic and local effects, positively modulating the infarction microenvironment. Poly‐(l ‐lactide) electrospun scaffolds were seeded with C2C12 murine skeletal myoblast for 48 hrs. Biological assays demonstrated the induction of Cx43 expression along with morphostructural changes resulting in cell elongation and appearance of cellular junctions resembling the usual cardiomyocyte arrangement at the ultrastructural level. The possibility of fabricating extracellular matrix‐mimicking scaffolds able to promote myoblast pre‐commitment towards myocardiocyte lineage and mitigate the hazardous environment of the damaged myocardium represents an interesting strategy in cardiac tissue engineering.     

The structure of maize polyamine oxidase K300M mutant in complex with the natural substrates provides a snapshot of the catalytic mechanism of polyamine oxidation

Polyamine oxidases are FAD-dependent enzymes catalyzing the oxidation of polyamines at the secondary amino groups. Zea mays PAO (ZmPAO) oxidizes the carbon on the endo-side of the N5-nitrogen of spermidine (Spd) and spermine (Spm). The structure of ZmPAO revealed that the active site is formed by a catalytic tunnel in which the N5 atom of FAD lies in close proximity to the K300 side chain, the only active-site residue conserved in all PAOs. A water molecule, (HOH309), is hydrogen-bound to the amino group of K300 and mutation of this residue results in a 1400-fold decrease in the rate of flavin reduction. The structural studies on the catalytically impaired ZmPAO-K300M mutant described here show that substrates are bound in an 'out-of-register' mode and the HOH309 water molecule is absent in the enzyme-substrate complexes. Moreover, K300 mutation brings about a 60 mV decrease in the FAD redox potential and a 30-fold decrease in the FAD reoxidation rate, within a virtually unaltered geometry of the catalytic pocket. Taken together, these results indicate that the HOH309-K300 couple plays a major role in multiple steps of ZmPAO catalytic mechanism, such as correct substrate binding geometry as well as FAD reduction and reoxidation kinetics.     

Increased adipose protein carbonylation in human obesity

Insulin resistance is associated with obesity but mechanisms controlling this relationship in humans are not fully understood. Studies in animal models suggest a linkage between adipose reactive oxygen species (ROS) and insulin resistance. ROS oxidize cellular lipids to produce a variety of lipid hydroperoxides that in turn generate reactive lipid aldehydes that covalently modify cellular proteins in a process termed carbonylation. Mammalian cells defend against reactive lipid aldehydes and protein carbonylation by glutathionylation using glutathione-S-transferase A4 (GSTA4) or carbonyl reduction/oxidation via reductases and/or dehydrogenases. Insulin resistance in mice is linked to ROS production and increased level of protein carbonylation, mitochondrial dysfunction, decreased insulin-stimulated glucose transport, and altered adipokine secretion. To assess protein carbonylation and insulin resistance in humans, eight healthy participants underwent subcutaneous fat biopsy from the periumbilical region for protein analysis and frequently sampled intravenous glucose tolerance testing to measure insulin sensitivity. Soluble proteins from adipose tissue were analyzed using two-dimensional gel electrophoresis and the major carbonylated proteins identified as the adipocyte and epithelial fatty acid-binding proteins. The level of protein carbonylation was directly correlated with adiposity and serum free fatty acids (FFAs). These results suggest that in human obesity oxidative stress is linked to protein carbonylation and such events may contribute to the development of insulin resistance.     

A topological framework for the computation of the HOMFLY polynomial and its application to proteins

Polymers can be modeled as open polygonal paths and their closure generates knots. Knotted proteins detection is currently achieved via high-throughput methods based on a common framework insensitive to the handedness of knots. Here we propose a topological framework for the computation of the HOMFLY polynomial, an handedness-sensitive invariant. Our approach couples a multi-component reduction scheme with the polynomial computation. After validation on tabulated knots and links the framework was applied to the entire Protein Data Bank along with a set of selected topological checks that allowed to discard artificially entangled structures. This led to an up-to-date table of knotted proteins that also includes two newly detected right-handed trefoil knots in recently deposited protein structures. The application range of our framework is not limited to proteins and it can be extended to the topological analysis of biological and synthetic polymers and more generally to arbitrary polygonal paths.     

Lactobacillus rhamnosus HN001 attenuates allergy development in a pig model

Background

Probiotics have been studied as immunomodulatory agents of allergy. Several human probiotic trials tracking the development of eczema and other forms of allergy have yielded inconsistent results. A recent infant study demonstrated that pre and postnatal Lactobacillus rhamnosus HN001 (HN001) supplementation decreased the prevalence of eczema and IgE associated eczema. However, the influence of HN001 on the incidence of wheeze, asthma, and/or other allergic manifestations has yet to be reported.

Objective

This study was conducted to determine the effects of the probiotic HN001 on the development of allergic lung disease in a pig model.

Methods

Allergy was induced by a series of subcutaneous and intratracheal sensitizations with Ascaris suum allergen (ASA) during a six week time frame in post-weanling pigs supplemented daily with HN001, or without supplementation. One week following final sensitization intradermal skin tests and respiratory challenges were conducted.

Results

In response to intradermal and respiratory challenges, ASA-sensitized pigs fed HN001 had less severe skin flare reactions, smaller increases in pleural pressure, and trends towards lower changes in arterial oxygen and carbon dioxide partial pressure levels compared to control pigs. The frequency of ASA-specific IFN-γ-secreting peripheral blood mononuclear cells, as well as the amount of IL-10 produced by ASA-specific cells, was of greater magnitude in probiotic-fed pigs compared to control animals. These observations suggest that differences in clinical responses to the allergen challenges may be related to probiotic-induced modulation of Th1 (IFN-γ) and regulatory (IL-10) cytokine expression.

Conclusions

Probiotic supplementation decreased the severity of allergic skin and lung responses in allergen-sensitized pigs with a corresponding increase in IFN-γ expression. A similar correlation between certain allergic responses and increased IFN-γ expression has been reported in human clinical studies of allergy; this pig model of allergy may be indicative of potential probiotic modulation of allergic lung disease in humans.     

Evolution of the ABPA Subunit of Androgen-Binding Protein Expressed in the Submaxillary Glands in New and Old World Rodent Taxa

The salivary androgen-binding proteins (ABPs) are members of the secretoglobin gene family present in mammals. Each ABP is a heterodimer assembled as an ABPA subunit encoded by an Abpa gene and linked by disulfide bridges to an ABPBG subunit encoded by an Abpbg gene. The ABP dimers are secreted into the saliva of mice and then transferred to the pelage after grooming and subsequently to the environment allowing an animal to mark territory with a biochemical signal. The putative role of the mouse salivary ABPs is that of pheromones mediating mate selection resulting in assortative mating in the Mus musculus species complex. We focused on comparing patterns of molecular evolution between the Abpa genes expressed in the submaxillary glands of species of New World and Old World muroids. We found that in both sets of rodents the Abpa genes expressed in the submaxillary glands appear to be evolving under a similar evolutionary regime, with relatively high nonsynonymous substitution rates, suggesting that ABP might play a similar biological role in both systems. Thus, ABP could be involved with mate recognition and species isolation in New World as well as Old World muroids.     

A possible pterosaur manus track from the Late Cretaceous of Alberta

An isolated track from the latest Campanian–Maastrichtian Wapiti Formation (Alberta) is tentatively identified as a pterosaur manus print. The basic digital formula (digit I < digit II < digit III) is consistent with the plesiomorphic condition in pterosaurs. The track measures 25.5 cm in length, making it the largest putative pterosaur manus print (estimated wingspan 7.7 m) from North America. Although precise chronostratigraphic data are lacking, sedimentary evidence indicates the track comes from a mid‐ to late Campanian fluvial deposits that accumulated approximately 400 km from the closest shoreline within a high‐latitude (65°N) setting.