Lipid profile: causal relationship on cognitive performance in multiple sclerosis?

Molecular Biology Reports - Although cognitive impairment (CI) is classically associated with aging, it has been proposed that neurological pathologies may increase the risk to suffer CI. Despite...     

A synthetic biology approach for the fabrication of functional (fluorescent magnetic) bioorganic–inorganic hybrid materials in sponge primmorphs

During evolution, sponges (Porifera) have honed the genetic toolbox and biosynthetic mechanisms for the fabrication of siliceous skeletal components (spicules). Spicules carry a protein scaffold embedded within biogenic silica (biosilica) and feature an amazing range of optical, structural, and mechanical properties. Thus, it is tempting to explore the low-energy synthetic pathways of spiculogenesis for the fabrication of innovative hybrid materials. In this synthetic biology approach, the uptake of multifunctional nonbiogenic nanoparticles (fluorescent, superparamagnetic) by spicule-forming cells of bioreactor-cultivated sponge primmorphs provides access to spiculogenesis. The ingested nanoparticles were detected within intracellular vesicles resembling silicasomes (silica-rich cellular compartments) and as cytosolic clusters where they lent primmorphs fluorescent/magnetic properties. During spiculogenesis, the nanoparticles initially formed an incomplete layer around juvenile, intracellular spicules. In the mature, extracellular spicules the nanoparticles were densely arranged as a surface layer that rendered the resulting composite fluorescent and magnetic. By branching off the conventional route of solid-state materials synthesis under harsh conditions, a new pathway has been opened to a versatile platform that allows adding functionalities to growing spicules as templates in living cells, using nonbiogenic nanoscale building blocks with multiple functionalities. The magnet-assisted alignment renders this composite with its fluorescent/magnetic properties potentially suitable for application in biooptoelectronics and microelectronics (e.g., microscale on-chip waveguides for applications of optical detection and sensing).     

High temporal and individual variation in the prevalence and intensity of chytrid infection in the southernmost Leaf Frog of the genus Pithecopus (Anura,Phyllomedusidae)

Hydrobiologia - Pithecopus rusticus is an endemic amphibian restricted to the type locality, in southern Brazil, and possibly endangered to extinction, due to habitat degradation. However, an...     

The novel NhaE-type Na+/H+ antiporter of the pathogenic bacterium Neisseria meningitidis

Neisseria meningitidis is a pathogenic bacterium responsible for meningitis. The mechanisms underlying the control of Na⁺ transmembrane movement, presumably important to pathogenicity, have been barely addressed. To elucidate the function of the components of the Na⁺ transport system in N. meningitidis, an open reading frame from the genome of this bacterium displaying similarity with the NhaE type of Na⁺/H⁺ antiporters was expressed in Escherichia coli and characterized for sodium transport ability. The N. meningitidis antiporter (NmNhaE) was able to complement an E. coli strain devoid of Na⁺/H⁺ antiporters (KNabc) respecting the ability to grow in the presence of NaCl and LiCl. Ion transport assays in everted vesicles prepared from KNabc expressing NmNhaE from a plasmid confirmed its ability to translocate Na⁺ and Li⁺. Here is presented the characterization of the first NhaE from a pathogen, an important contribution to the comprehension of sodium ion metabolism in this kind of microorganisms.     

Development and application of a volume penalization immersed boundary method for the computation of blood flow and shear stresses in cerebral vessels and aneurysms

A volume-penalizing immersed boundary method is presented for the simulation of laminar incompressible flow inside geometrically complex blood vessels in the human brain. We concentrate on cerebral aneurysms and compute flow in curved brain vessels with and without spherical aneurysm cavities attached. We approximate blood as an incompressible Newtonian fluid and simulate the flow with the use of a skew-symmetric finite-volume discretization and explicit time-stepping. A key element of the immersed boundary method is the so-called masking function. This is a binary function with which we identify at any location in the domain whether it is ‘solid’ or ‘fluid’, allowing to represent objects immersed in a Cartesian grid. We compare three definitions of the masking function for geometries that are non-aligned with the grid. In each case a ‘staircase’ representation is used in which a grid cell is either ‘solid’ or ‘fluid’. Reliable findings are obtained with our immersed boundary method, even at fairly coarse meshes with about 16 grid cells across a velocity profile. The validation of the immersed boundary method is provided on the basis of classical Poiseuille flow in a cylindrical pipe. We obtain first order convergence for the velocity and the shear stress, reflecting the fact that in our approach the solid-fluid interface is localized with an accuracy on the order of a grid cell. Simulations for curved vessels and aneurysms are done for different flow regimes, characterized by different values of the Reynolds number ( $Re$ ). The validation is performed for laminar flow at $Re=250$ , while the flow in more complex geometries is studied at $Re = 100$ and $Re = 250$ , as suggested by physiological conditions pertaining to flow of blood in the circle of Willis.     

Neuroprotection of medical IOP-lowering therapy

Intraocular pressure (IOP)-lowering therapy has been shown to arrest or retard the progression of optic neuropathy typical for glaucoma and can, thus, be described as neuroprotective. At present, six classes of medical therapy are employed, namely parasympathomimetics, alpha/beta-sympathomimetics, β-blockers, carbonic anhydrase inhibitors, α₂-adrenergic receptor agonists and prostaglandin analogues. For several of these substances, some experimental evidence exists of a possible neuroprotective mechanism, beyond their IOP-lowering activity. β-Blockers are involved in the up-regulation of brain-derived neurotrophic factor (BDNF) and can decrease glutamate-mediated NMDA receptor activation. Not only systemic but also topical carbonic anhydrase inhibitors are able to increase retinal blood flow. α₂-Adrenergic receptor agonists can up-regulate the formation of BDNF and anti-apoptotic factors. Prostaglandin analogues increase blood flow to the eye, possibly including the retina. To date, evidence for a neuroprotective effect independent of IOP regulation in human glaucoma is scarce and has only been shown to be likely for the α₂-adrenergic receptor agonist, brimonidine.     

Ecological photodynamic therapy: New trend to disrupt the intricate networks within tumor ecosystem

As with natural ecosystems, species within the tumor microenvironment are connected by pairwise interactions (e.g. mutualism, predation) leading to a strong interdependence of different populations on each other. In this review we have identified the ecological roles played by each non-neoplastic population (macrophages, endothelial cells, fibroblasts) and other abiotic components (oxygen, extracellular matrix) directly involved with neoplastic development. A way to alter an ecosystem is to affect other species within the environment that are supporting the growth and survival of the species of interest, here the tumor cells; thus, some features of ecological systems could be exploited for cancer therapy. We propose a well-known antitumor therapy called photodynamic therapy (PDT) as a novel modulator of ecological interactions. We refer to this as “ecological photodynamic therapy.” The main goal of this new strategy is the improvement of therapeutic efficiency through the disruption of ecological networks with the aim of destroying the tumor ecosystem. It is therefore necessary to identify those interactions from which tumor cells get benefit and those by which it is impaired, and then design multitargeted combined photodynamic regimes in order to orchestrate non-neoplastic populations against their neoplastic counterpart. Thus, conceiving the tumor as an ecological system opens avenues for novel approaches on treatment strategies.     

A review of the allozyme data set for the Canarian endemic flora: causes of the high genetic diversity levels and implications for conservation

Background and Aims

Allozyme and reproductive data sets for the Canarian flora are updated in order to assess how the present levels and structuring of genetic variation have been influenced by the abiotic island traits and by phylogenetically determined biotic traits of the corresponding taxa; and in order to suggest conservation guidelines.

Methods

Kruskal–Wallis tests are conducted to assess the relationships of 27 variables with genetic diversity (estimated by A, P, H_o and H_e) and structuring (G_ST) of 123 taxa representing 309 populations and 16 families. Multiple linear regression analyses (MLRAs) are carried out to determine the relative influence of the less correlated significant abiotic and biotic factors on the genetic diversity levels.

Key Results and Conclusions

The interactions between biotic features of the colonizing taxa and the abiotic island features drive plant diversification in the Canarian flora. However, the lower weight of closeness to the mainland than of (respectively) high basic chromosome number, partial or total self-incompatibility and polyploidy in the MLRAs indicates substantial phylogenetic constraint; the importance of a high chromosome number is feasibly due to the generation of a larger number of linkage groups, which increase gametic and genotypic diversity. Genetic structure is also more influenced by biotic factors (long-range seed dispersal, basic chromosome number and partial or total self-incompatibility) than by distance to the mainland. Conservation-wise, genetic structure estimates (F_ST/G_ST) only reflect endangerment under intensive population sampling designs, and neutral genetic variation levels do not directly relate to threat status or to small population sizes. Habitat protection is emphasized, but the results suggest the need for urgent implementation of elementary reproductive studies in all cases, and for ex situ conservation measures for the most endangered taxa, even without prior studies. In non-endangered endemics, multidisciplinary research is needed before suggesting case-specific conservation strategies. The molecular information relevant for conservation should be conserved in a standardized format to facilitate further insight.