Janus-faced role of endothelial NO synthase in vascular disease: uncoupling of oxygen reduction from NO synthesis and its pharmacological reversal

Endothelial NO synthase (eNOS) is the predominant enzyme responsible for vascular NO synthesis. A functional eNOS transfers electrons from NADPH to its heme center, where L-arginine is oxidized to L-citrulline and NO. Common conditions predisposing to atherosclerosis, such as hypertension, hypercholesterolemia, diabetes mellitus and smoking, are associated with enhanced production of reactive oxygen species (ROS) and reduced amounts of bioactive NO in the vessel wall. NADPH oxidases represent major sources of ROS in cardiovascular pathophysiology. NADPH oxidase-derived superoxide avidly interacts with eNOS-derived NO to form peroxynitrite (ONOO(-)), which oxidizes the essential NOS cofactor (6R-)5,6,7,8-tetrahydrobiopterin (BH(4)). As a consequence, oxygen reduction uncouples from NO synthesis, thereby rendering NOS to a superoxide-producing pro-atherosclerotic enzyme. Supplementation with BH(4) corrects eNOS dysfunction in several animal models and in patients. Administration of high local doses of the antioxidant L-ascorbic acid (vitamin C) improves endothelial function, whereas large-scale clinical trials do not support a strong role for oral vitamin C and/or E in reducing cardiovascular disease. Statins, angiotensin-converting enzyme inhibitors and AT1 receptor blockers have the potential of reducing vascular oxidative stress. Finally, novel approaches are being tested to block pathways leading to oxidative stress (e.g. protein kinase C) or to upregulate antioxidant enzymes.     

Psb27, a cyanobacterial lipoprotein, is involved in the repair cycle of photosystem II

Photosystem II (PSII) performs one of the key reactions on our planet: the light-driven oxidation of water. This fundamental but very complex process requires PSII to act in a highly coordinated fashion. Despite detailed structural information on the fully assembled PSII complex, the dynamic aspects of formation, processing, turnover, and degradation of PSII with at least 19 subunits and various cofactors are still not fully understood. Transient complexes are especially difficult to characterize due to low abundance, potential heterogeneity, and instability. Here, we show that Psb27 is involved in the assembly of the water-splitting site of PSII and in the turnover of the complex. Psb27 is a bacterial lipoprotein with a specific lipid modification as shown by matrix-assisted laser-desorption ionization time of flight mass spectrometry. The combination of HPLC purification of four different PSII subcomplexes and (15)N pulse label experiments revealed that lipoprotein Psb27 is part of a preassembled PSII subcomplex that represents a distinct intermediate in the repair cycle of PSII.     

Identification of a novel, highly variable amino-terminal amino acid sequence element in the nuclear intermediate filament protein lamin B(2) from higher vertebrates

By comparing newly available cDNA sequences of the human intermediate filament protein lamin B(2) with published sequences, we have identified an additional translation initiation codon 60 nucleotides upstream of the previously assumed translation start. In addition, corresponding sequences were identified in the chimpanzee, mouse, rat and bovine genes and cDNAs, respectively. Therefore, we generated antibodies against these potential 20 new amino acids of the human sequence. By immunoblot analysis and immunofluorescence microscopy we show that human lamin B(2) is indeed synthesized as a longer version than previously reported, because it contains these additional 20 amino acids. Notably, the sequence homology to mouse, rat and bovine lamin B(2) is significantly lower in this segment than in that between the second methionine codon and the start of the alpha-helical rod indicating that the tip of the "head" is engaged in more species-specific functions. Forced expression of the GFP-tagged authentic "long" and the 20 amino acid shorter version of lamin B(2) in human cultured SW-13 cells demonstrated that both the longer and the shorter version are properly integrated into the nuclear lamina, although the shorter version exhibited a tendency to disturb envelope architecture at higher expression levels.     

Monitoring the Early Signs of Cognitive Decline in Elderly by Computer Games: An MRI Study

BackgroundIt is anticipated that current and future preventive therapies will likely be more effective in the early stages of dementia, when everyday functioning is not affected. Accordingly the early identification of people at risk is particularly important. In most cases, when subjects visit an expert and are examined using neuropsychological tests, the disease has already been developed. Contrary to this cognitive games are played by healthy, well functioning elderly people, subjects who should be monitored for early signs. Further advantages of cognitive games are their accessibility and their cost-effectiveness.PurposeThe aim of the investigation was to show that computer games can help to identify those who are at risk. In order to validate games analysis was completed which measured the correlations between results of the ''Find the Pairs'' memory game and the volumes of the temporal brain regions previously found to be good predictors of later cognitive decline.ResultsThere was a correlation between the number of attempts and the time required to complete the memory game and the volume of the entorhinal cortex, the temporal pole, and the hippocampus. There was also a correlation between the results of the Paired Associates Learning (PAL) test and the memory game.ConclusionsThe results gathered support the initial hypothesis that healthy elderly subjects achieving lower scores in the memory game have increased level of atrophy in the temporal brain structures and showed a decreased performance in the PAL test. Based on these results it can be concluded that memory games may be useful in early screening for cognitive decline.     

Characterization of a model cyanobacterium Synechocystis sp. PCC 6803 autotrophic growth in a flat‐panel photobioreactor

We characterized the photoautotrophic growth of glucose‐tolerant Synechocystis sp. PCC 6803 in a flat‐panel photobioreactor running on a semicontinuous regime under various lights, temperatures, and influx carbon dioxide concentrations. The maximum reached growth rate was 0.135 h^?1, which corresponds to a doubling time of 5.13 h—a growth speed never reported for Synechocystis before. Saturating red light intensity for the strain was 220–360 μmol(photons) m^?2 s^?1, and we did not observe any photoinhibition up to 660 μmol(photons) m^?2 s^?1. Synechocystis was able to grow under red light only; however, photons of wavelengths 405–585 and 670–700 nm further improved its growth. Optimal growth temperature was 35°C. Below 32°C, the growth rates decreased linearly with temperature coefficient (Q₁₀) 1.70. Semicontinuous cultivation is known to be efficient for growth characterization and optimization. However, the assumption of correct growth rates calculation—culture exponential growth—is often not fulfilled. The semicontinuous setup in this study was operated as a turbidostat. Accurate online OD measurements with high time‐resolution allowed fast and reliable growth rates determination. Repeating diluting frequencies (up to 18 dilutions per day) were essential for rapid growth stability evaluation. The presented setup provides improvement to previously published semicontinuous characterization strategies by decreasing experimental time requirements and maintaining the culture in exponential growth phase throughout the entire characterization procedure.     

Plants protect their roots by alerting the enemies of grubs

Plant roots in the soil are under attack from many soil organisms. Although many ecologists are aware of the presence and importance of natural enemies in the soil that protect the plants from herbivores, the existence and nature of tritrophic interactions are poorly understood. So far, attention has focused on how plants protect their above-ground parts against herbivorous arthropods, either directly or indirectly (i.e. by getting help from the herbivore's enemies). This article is the first in showing that indirect plant defences also operate underground. We show that the roots of a coniferous plant ( Thuja occidentalis ) release chemicals upon attack by weevil larvae ( Otiorhynchus sulcatus ) and that these chemicals thereby attract parasitic nematodes ( Heterorhabditis megidis ).     

1H-nmr study on the preferred conformations of chiral pyridine-dinucleotide models

The synthesis of four chiral NAD⁺ models 1 and their 1,4-dihydro analogs 2 is described. From the temperature dependence of the ¹H-nmr spectra it is concluded that for these compounds two preferred conformations I and II, differing slightly in energy, exist. Both conformations are “folded” with the more or less parallel p-anisyl and pyridine groups mutually gauche, but in I the pyridine group is rotated by about 180° as compared with II, thus leading to a conspicuous difference in orientation of the substituent Z (NH₂CO, C₆H₅NHSO₂, (CH₂)₄NSO₂, or (C₄H₈ON)SO₂) in the pyridine ring toward the anisyl group. The most stable conformation (I) has Z closest to the center of the p-anisyl group. In 360-MHz spectra of the dihydropyridines at low temperature (?10°C), slow interconversion of I and II leads to the observation of an XY pattern for the C-4 methylene protons of the 1,4-dihydropyridine system. The anisochronity in this methylene group is caused mainly by the anisotropy of the neighboring p-anisyl group.     

Cytolytic T cells activated by H-2-controlled E molecules cross-react with A molecules

Cell-mediated lymphocytotoxicity was generated in four strain combinations differing only by the cell-surface expression of the class II E molecule controlled by the H-2 complex. The four combinations were: B10.D2(R107) anti-B10.A(3R), B10.A(4R) anti-B10.A(2R), B10.GD anti-B10.D2(R101), and B10.S(7R) anti-B10.S(9R). In all four of these combinations, the stimulator expresses E molecules on the cell surface, while the responder does not. The cytolytic T lymphocytes generated in the B10.D2(R107) anti-B10.A(3R) and B10.A(4R) anti-B10.A(2R) combinations reacted not only with the stimulator but also with strains that do not express cell-surface E molecules, in particular, strains carrying the H-2 ^f and H-2 ^q haplotypes. The cross-reactivity with E-negative strains could be blocked by monoclonal antibodies specific for the A^f or A^q molecules but not by antibodies recognizing determinants on E or class I (K) molecules. The anti-H-2^f cross-reactivity could be inhibited by H-2 ^q cold targets and, reciprocally, the anti-H-2^q reactivity could be blocked by H-2 ^f cold targets. These findings are interpreted as indicating that the cytolytic T lymphocytes stimulated by E molecules can recognize and lyse cells lacking E molecules but expressing A molecules. The observed E-A cross-reactivity supports the notion of structural and functional relatedness between the A and E molecules and suggests a common evolutionary origin of the A- and E-encoding loci.