Formation and Characterization of Supported Lipid Bilayers Composed of Hydrogenated and Deuterated Escherichia coli Lipids

Supported lipid bilayers are widely used for sensing and deciphering biomolecular interactions with model cell membranes. In this paper, we present a method to form supported lipid bilayers from total lipid extracts of Escherichia coli by vesicle fusion. We show the validity of this method for different types of extracts including those from deuterated biomass using a combination of complementary surface sensitive techniques; quartz crystal microbalance, neutron reflection and atomic force microscopy. We find that the head group composition of the deuterated and the hydrogenated lipid extracts is similar (approximately 75% phosphatidylethanolamine, 13% phosphatidylglycerol and 12% cardiolipin) and that both samples can be used to reconstitute high-coverage supported lipid bilayers with a total thickness of 41 ± 3 Å, common for fluid membranes. The formation of supported lipid bilayers composed of natural extracts of Escherichia coli allow for following biomolecular interactions, thus advancing the field towards bacterial-specific membrane biomimics.     

Reliability of Intra-Retinal Layer Thickness Estimates

Purpose

Measurement of intra-retinal layer thickness using optical coherence tomography (OCT) has become increasingly prominent in multiple sclerosis (MS) research. Nevertheless, the approaches used for determining the mean layer thicknesses vary greatly. Insufficient data exist on the reliability of different thickness estimates, which is crucial for their application in clinical studies. This study addresses this lack by evaluating the repeatability of different thickness estimates.

Methods

Studies that used intra-retinal layer segmentation of macular OCT scans in patients with MS were retrieved from PubMed. To investigate the repeatability of previously applied layer estimation approaches, we generated datasets of repeating measurements of 15 healthy subjects and 13 multiple sclerosis patients using two OCT devices (Cirrus HD-OCT and Spectralis SD-OCT). We calculated each thickness estimate in each repeated session and analyzed repeatability using intra-class correlation coefficients and coefficients of repeatability.

Results

We identified 27 articles, eleven of them used the Spectralis SD-OCT, nine Cirrus HD-OCT, two studies used both devices and two studies applied RTVue-100. Topcon OCT-1000, Stratus OCT and a research device were used in one study each. In the studies that used the Spectralis, ten different thickness estimates were identified, while thickness estimates of the Cirrus OCT were based on two different scan settings. In the simulation dataset, thickness estimates averaging larger areas showed an excellent repeatability for all retinal layers except the outer plexiform layer (OPL).

Conclusions

Given the good reliability, the thickness estimate of the 6mm-diameter area around the fovea should be favored when OCT is used in clinical research. Assessment of the OPL was weak in general and needs further investigation before OPL thickness can be used as a reliable parameter.     

Complex of Rutin with β-Cyclodextrin as Potential Delivery System

This study aimed to obtain and characterize an RU-β-CD complex in the context of investigating the possibility of changes in the solubility, stability, antioxidative and microbiological activity as well as permeability of complexated rutin as against its free form. The formation of the RU-β-CD complex via a co-grinding technique was confirmed by using DSC, SEM, FT-IR and Raman spectroscopy, and its geometry was assessed through molecular modeling. It was found that the stability and solubility of the so-obtained complex were greater compared to the free form; however, a slight decrease was observed inits antibacterial potency. An examination of changes in the EPR spectra of thecomplex excluded any reducing effect of complexation on the antioxidative activity of rutin. Considering the prospect of preformulation studies involving RU-β-CD complexes, of significance is also the observed possibility of prolongedly releasing rutin from the complex at a constant level over along period of 20 h, and the fact that twice as much complexated rutin was able topermeate compared to its free form.     

SEXUALLY SELECTED TRAITS EVOLVE POSITIVE ALLOMETRY WHEN SOME MATINGS OCCUR IRRESPECTIVE OF THE TRAIT

Positive allometry of secondary sexual traits (whereby larger individuals have disproportionally larger traits than smaller individuals) has been called one of the most pervasive and poorly understood regularities in the study of animal form and function. Its widespread occurrence is in contrast with theoretical predictions that it should evolve only under rather special circumstances. Using a combination of mathematical modeling and simulations, here we show that positive allometry is predicted to evolve under much broader conditions than previously recognized. This result hinges on the assumption that mating success is not necessarily zero for males with the lowest trait values: for example, a male who lacks horns or antlers might still be able to copulate if encountering an unguarded female. We predict the strongest positive allometry when males typically (but not always) compete in large groups, and when trait differences decisively determine the outcome of competitive interactions.     

Bone Marrow Involvement in a Patient with Paracoccidioidomycosis: A Rare Presentation of Juvenile Form

Paracoccidioides brasiliensis rarely shows bone marrow involvement and its response to treatment with itraconazole in children needs further assessment. We describe here a child with a juvenile disseminated form of paracoccidioidomycosis, which showed reticuloendothelial system involvement and the presence of Paracoccidioides brasiliensis in the bone marrow. The patient showed an effective and rapid response to itraconazole therapy.     

Anti-neoplastic effect of protein kinase CK2 inhibitor, 2-dimethylamino-4,5,6,7-tetrabromobenzimidazole (DMAT), on growth and hormonal activity of human adrenocortical carcinoma cell line (H295R) in vitro

Several studies indicate the involvement of protein kinases in the progression of various malignancies. Kinase inhibitors are therefore becoming important anticancer drugs. CK2 kinase (casein kinase-2) has been suggested to be a constituent of a neoplastic milleu, and its inhibition might represent a new approach to cancer therapy. Adrenocortical carcinomas (ACCs) are highly malignant neoplasms with poor overall prognosis. We have examined the effects of 2-dimethylamino-4,5,6,7-tetrabromobenzimidazole (DMAT), a potent CK2 inhibitor, on the H295R human adrenocortical cancer cell line. Treatment with DMAT decreases the secretion of aldosterone, dehydroepiandrosterone sulfate, and androstendione and results in an accumulation of 17-OH-progesterone. Cell growth as measured by the MTT and 5-bromo-2′-deoxyuridine incorporation assays is inhibited, and cell cycle analysis has revealed a slight induction of apoptosis. Thus, CK2 kinase activity is probably involved in human ACC endocrine activity and growth.     

Suppression of DNA-PKcs enhances FGF-2 dependent human endothelial cell proliferation via negative regulation of Akt

Angiogenesis initiation is crucially dependent on endothelial proliferation and can be stimulated by the fibroblast growth factor 2 (FGF-2). The DNA dependent protein kinase (DNA-PK), long known for its importance in repairing DNA double strand breaks, belongs to the phosphatidylinositol-3 kinase (PI3-K) super family and has recently been identified as one of the enzymes phosphorylating and activating Akt. Due to its similarity with PI3-K, we hypothesized that DNA-PK may have similar effects on endothelial angiogenic processes and signalling. We used primary endothelial cells (HUVEC and PAEC) and human microvascular endothelial cells (HMEC) to study the role of DNA-PK in endothelial proliferation and signalling. DNA-PKcs suppression with the compound NU7026 or with siRNA induced basal endothelial cell proliferation as well as enhanced FGF-2 dependent proliferation. This was associated with an increase in phosphorylated Akt. Tube formation was not affected by DNA-PKcs clearly showing that the role of DNA-PK in endothelial processes differs from that of PI3-K. Our findings indicate DNA-PK as an important enzyme maintaining the quiescent endothelial phenotype by actively inhibiting Akt thus restraining endothelial cell proliferation preventing excessive growth.     

Fitness costs associated with low genetic variation are reduced in a harsher environment in amphibian island populations

A basic premise of conservation geneticists is that low levels of genetic variation are associated with fitness costs in terms of reduced survival and fecundity. These fitness costs may frequently vary with environmental factors and should increase under more stressful conditions. However, there is no consensus on how fitness costs associated with low genetic variation change under natural conditions in relation to the stressfulness of the environment. On the Swedish west coast, natterjack toad Bufo calamita populations show a strong population genetic structure and large variation in the amount of within-population genetic variation. We experimentally examined the survival of natterjack larvae from six populations with different genetic variation in three thermal environments corresponding to (a) the mean temperature of natural ponds (stable, laboratory), (b) a high temperature environment occurring in desiccating ponds (stable, laboratory) and (c) an outdoor treatment mimicking the natural, variable thermal conditions (fluctuating, semi-natural). We found that larvae in the outdoor treatment had poorer survival than larvae in the stable environments suggesting that the outdoor treatment was more stressful. Overall, populations with higher genetic variation had higher larval survival. However, a significant interaction between treatments and genetic variation indicated that fitness costs associated with low genetic variation were less severe in the outdoor treatment. Thus, we found no support for the hypothesis that fitness costs associated with low genetic variation increase under more stressful conditions. Our results suggest that natural thermal stress may mask fitness losses associated with low genetic variation in these populations.