Blood Plasma TGF- β1 Concentration in Sporadic Dilatative Pathology of Ascending Aorta: More Questions than Answers

Transforming growth factor β1 (TGF- β1) is a cytokine that participates in a broad range of cellular regulatory processes and is associated with various diseases including aortic aneurysm. Increased TGF- β1 levels are associated with Marfan syndrome (MFS) caused by FBN1 mutations and subsequent defects in signaling system. We studied TGF- β1 levels in 62 patients with sporadic, non syndromic, dilatative pathology of ascending aorta (DPAA) and in reference group subjects (n = 212). An initial screening of 212 reference individuals identified TGF- β1 gender discrepancies and age-dependent cytokine increase in women. Patients with DPAA had increased levels of TGF- β1 in comparison to reference group subjects (median 7.7 ng/ml, range 2.1–25.3, and median 6.2 ng/ml, range 1.0–33.1, respectively). There is a significant association between TGF-β1 concentration and DPAA (OR 1.084, CI 1.027–1.144, p = 0.004) but the mechanisms of cause and effect have not been established yet. Slightly increased TGF-β1 concentrations in patients with sporadic DPAA in comparison to the reference subjects show a potential use of TGF-β1 as a biomarker for the disease. However, cytokine dependence on age, gender, and other unknown factors among individuals with no cardiovascular complains reduces its specificity for DPAA. We would also like to raise awareness regarding the choice of methods when measuring TGF-β1 levels with an emphasis on preanalytical phase and the choice of sample.     

Osmotic stress responses of individual white oak (Quercus section, Quercus subgenus) genotypes cultured in vitro

White oaks (Quercus section, Quercus subgenus) are widely distributed in Europe. Quercus petraea (sessile oak), an economically important species is predicted to be affected by climate change. Q. pubescens (pubescent oak) and Q. virgiliana (Italian pubescent oak) are economically less important, drought tolerant species. Frequent hybridization of white oaks was observed and currently the introgression of Q. pubescens and Q. virgiliana in non-mediterranean regions of Europe has been reported. Our goal was to use tissue cultures established from individual trees of the above taxa and their putative hybrids, all present in the forest stand of Síkf?kút LTER Research Area (NE Hungary) as simple experimental model systems for studying drought/osmotic stress tolerance. Tissue cultures are more suitable models for such studies, than seedlings, because they are genetically identical to the parent plants. Polyethylene glycol (PEG6000) treatments were used for this purpose. The identification of taxa was based on leaf morphological traits and microsatellite analysis and showed that Q. petraea is genetically distinct to all other taxa examined. We established six callus lines of Quercus. As expected, in Q. petraea cultures PEG6000 induced severe loss of fresh weight and the ability to recover after removal of the osmoticum, which was not characteristic for Q. pubescens and Q. virgiliana. Putative hybrids exhibited an intermediate response to osmotic stress. Activity gels showed the increase of single-strand preferring (SSP) nuclease and no significant change of guaiacol-peroxidase activities in drought-sensitive genotypes/cultures and no significant increase of SSP nuclease activities accompanied with increases of guaiacol-peroxidase activities in drought-tolerant ones. This indicates that drought/osmotic stress tolerance is associated to increased capacity of scavenging reactive oxygen species and hence less susceptibility to DNA damage. Our results confirm that tissue cultures of oak are suitable model systems for studying drought/osmotic stress responses.     

A novel SOD-mimetic permeability transition inhibitor agent protects ischemic heart by inhibiting both apoptotic and necrotic cell death

In ischemia-reperfusion injuries, elevated calcium and reactive oxygen species (ROS) induce mitochondrial permeability transition (mPT), which plays a pivotal role in mediating damages and cell death. Inhibition of mPT decreases necrotic cell death; however, during reperfusion, the continuous production of ROS may contribute to the temporary opening of the pore and thus the onset of the delayed apoptotic cell death. Based on amiodarone structure, we developed the first SOD-mimetic mPT inhibitor (HO-3538) that can eliminate ROS in the microenvironment of the permeability pore. In isolated mitochondria, HO-3538 inhibited mPT and the release of proapoptotic mitochondrial proteins. It had a ROS scavenging effect and antiapoptotic effect in a cardiomyocyte line and it diminished release of mitochondrial proapoptotic proteins. Furthermore, HO-3538 significantly enhanced the recovery of mitochondrial energy metabolism and functional cardiac parameters; decreased infarct size, lipid peroxidation, and protein oxidation; and suppressed necrotic as well as apoptotic cell death pathways in Langendorff-perfused hearts. In these respects it was somewhat superior to its two constituents, amiodarone and a pyrrol-derivative free radical scavenger. These data suggest that the SOD-mimetic mPT inhibitors are ideal candidates for drug development for the alleviation of postinfarct myocardial injuries.     

Enzymic analysis of NADPH metabolism in beta-lactam-producing Penicillium chrysogenum: presence of a mitochondrial NADPH dehydrogenase

Based on assumed reaction network structures, NADPH availability has been proposed to be a key constraint in beta-lactam production by Penicillium chrysogenum. In this study, NADPH metabolism was investigated in glucose-limited chemostat cultures of an industrial P. chrysogenum strain. Enzyme assays confirmed the NADP(+)-specificity of the dehydrogenases of the pentose-phosphate pathway and the presence of NADP(+)-dependent isocitrate dehydrogenase. Pyruvate decarboxylase/NADP(+)-linked acetaldehyde dehydrogenase and NADP(+)-linked glyceraldehyde-3-phosphate dehydrogenase were not detected. Although the NADPH requirement of penicillin-G-producing chemostat cultures was calculated to be 1.4-1.6-fold higher than that of non-producing cultures, in vitro measured activities of the major NADPH-providing enzymes were the same. Isolated mitochondria showed high rates of antimycin A-sensitive respiration of NADPH, thus indicating the presence of a mitochondrial NADPH dehydrogenase that oxidises cytosolic NADPH. The presence of this enzyme in P. chrysogenum might have important implications for stoichiometric modelling of central carbon metabolism and beta-lactam production and may provide an interesting target for metabolic engineering.     

Spatio-temporal visual properties in the ascending tectofugal system

Our study compares the spatio-temporal visual receptive field properties of different subcortical stages of the ascending tectofugal visual system. Extracellular single-cell recordings were performed in the superficial (SCs) and intermediate (SCi) layers of the superior colliculus (SC), the suprageniculate nucleus (Sg) of the posterior thalamus and the caudate nucleus (CN) of halothane-anesthetized cats. Neuronal responses to drifting gratings of various spatial and temporal frequencies were recorded. The neurons of each structure responded optimally to low spatial and high temporal frequencies and displayed narrow spatial and temporal frequency tuning. The detailed statistical analysis revealed that according to its stimulus preferences the SCs has markedly different spatio-temporal properties from the homogeneous group formed by the SCi, Sg and CN. The SCs neurons preferred higher spatial and lower temporal frequencies and had broader spatial tuning than the other structures. In contrast to the SCs the visually active SCi, as well as the Sg and the CN neurons possessed consequently similar spatio-temporal preferences. These data support our hypothesis that the visually active SCi, Sg and CN neurons form a homogeneous neuronal population given a similar spatio-temporal frequency preference and a common function in processing of dynamic visual information.     

New short cationic antibacterial peptides. Synthesis,biological activity and mechanism of action

We report a theoretical and experimental study on a new series of small-sized antibacterial peptides. Synthesis and bioassays for these peptides are reported here. In addition, we evaluated different physicochemical parameters that modulate antimicrobial activity (charge, secondary structure, amphipathicity, hydrophobicity and polarity). We also performed molecular dynamic simulations to assess the interaction between these peptides and their molecular target (the membrane). Biophysical characterization of the peptides was carried out with different techniques, such as circular dichroism (CD), linear dichroism (LD), infrared spectroscopy (IR), dynamic light scattering (DLS), fluorescence spectroscopy and TEM studies using model systems (liposomes) for mammalian and bacterial membranes. The results of this study allow us to draw important conclusions on three different aspects. Theoretical and experimental results indicate that small-sized peptides have a particular mechanism of action that is different to that of large peptides. These results provide additional support for a previously proposed four-step mechanism of action. The possible pharmacophoric requirement for these small-sized peptides is discussed. Furthermore, our results indicate that a net +4 charge is the adequate for 9 amino acid long peptides to produce antibacterial activity. The information reported here is very important for designing new antibacterial peptides with these structural characteristics.