Effects of aminoguanidine and antioxidant erdosteine on bleomycin-induced lung fibrosis in rats.

Reactive oxygen and nitrogen species have been implicated in the pathogenesis of bleomycin-induced lung fibrosis. The effects of aminoguanidine and erdosteine on the bleomycin-induced lung fibrosis were evaluated in rats. The animals were placed into five groups: Vehicle + vehicle, vehicle + bleomycin (2.5 U/kg), bleomycin + aminoguanidine (200 mg/kg), bleomycin + erdosteine (10 mg/kg), and bleomycin + erdosteine + aminoguanidine. Bleomycin administration resulted in prominent lung fibrosis as measured by lung hydroxyproline content and lung histology, which is completely prevented by erdosteine and aminoguanidine. A strong staining for nitro tyrosine antibody in lung tissue and increased levels of lung NO were found in bleomycin group, that were significantly reduced by aminoguanidine and erdosteine. Aminoguanidine and erdosteine significantly prevented depletion of superoxide dismutase and glutathione peroxidase and elevated myeloperoxidase activities, malondialdehyde level in lung tissue produced by bleomycin. Data presented here indicate that aminoguanidine and erdosteine prevented bleomycin-induced lung fibrosis and that nitric oxide mediated tyrosine nitration of proteins plays a significant role in the pathogenesis of bleomycin-induced lung fibrosis. Also our data suggest that antifibrotic affect of antioxidants may be due to their inhibitory effect on nitric oxide generation in this model.     

Activities of free radical and DNA turn-over enzymes in cancerous and non-cancerous human brain tissues

Activities of adenosine deaminase (ADA), 5′ nucleotidase (5′NT), xanthine oxidase (XO), guanase (GUA), total superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) enzymes were measured in cancerous brain tissues from 48 patients. The results were compared with those of the control brain tissues from 17 subjects. Important differences were found between enzyme activities of control brain tissues and those of tumoral tissues.

There were important intracorrelations between some of the enzyme activities in both neoplastic and control brain tissues. The correlations exhibited significant differences between control group and patient groups, indicating disordered enzymatic relations in the cancerous brain tissues.

The results suggest that enzymatic make-up relating to free radical and purine metabolism shows great differences between cancerous and non-cancerous brain tissues. Similar diversity is also present between various types of cancerous brain tissues. This implies that enzymatic make-up of the tissues also depends on the cancer type. We thus suggest that the results obtained from this kind of experimental studies should be evaluated individually for the tissue analyzed taking the cancer type into consideration without making general evaluations.     

A Novel Receptor-induced Activation Site in the Nipah Virus Attachment Glycoprotein (G) Involved in Triggering the Fusion Glycoprotein (F)

Cellular entry of paramyxoviruses requires the coordinated action of both the attachment (G/H/HN) and fusion (F) glycoproteins, but how receptor binding activates G to trigger F-mediated fusion during viral entry is not known. Here, we identify a receptor (ephrinB2)-induced allosteric activation site in Nipah virus (NiV) G involved in triggering F-mediated fusion. We first generated a conformational monoclonal antibody (monoclonal antibody 45 (Mab45)) whose binding to NiV-G was enhanced upon NiV-G-ephrinB2 binding. However, Mab45 also inhibited viral entry, and its receptor binding-enhanced (RBE) epitope was temperature-dependent, suggesting that the Mab45 RBE epitope on G may be involved in triggering F. The Mab45 RBE epitope was mapped to the base of the globular domain (β6S4/β1H1). Alanine scan mutants within this region that did not exhibit this RBE epitope were also non-fusogenic despite their ability to bind ephrinB2, oligomerize, and associate with F at wild-type (WT) levels. Although circular dichroism revealed conformational changes in the soluble ectodomain of WT NiV-G upon ephrinB2 addition, no such changes were detected with soluble RBE epitope mutants or short-stalk G mutants. Additionally, WT G, but not a RBE epitope mutant, could dissociate from F upon ephrinB2 engagement. Finally, using a biotinylated HR2 peptide to detect pre-hairpin intermediate formation, a cardinal feature of F-triggering, we showed that ephrinB2 binding to WT G, but not the RBE-epitope mutants, could trigger F. In sum, we implicate the coordinated interaction between the base of NiV-G globular head domain and the stalk domain in mediating receptor-induced F triggering during viral entry.The paramyxoviruses comprise a group of important human pathogens, such as measles, mumps, human parainfluenza viruses, and the highly pathogenic Nipah (NiV)⁴ and Hendra (HeV) viruses. NiV infections have a mortality rate in humans of up to 75%, and NiV is classified as a BSL4 pathogen because of its bio- or agro-terrorism potential (1). The efficacy of entry inhibitors targeted against HIV suggests that a better understanding of Paramyxovirus entry and fusion will facilitate similarly efficacious antiviral therapeutics.Although past studies have identified regions in either the fusion (F) or attachment (G/H/HN) glycoproteins that are important for membrane fusion or F-G/H/HN association (2–10), the region(s) in G important for receptor-activated triggering of F-mediated fusion remains unknown. Current models of Paramyxovirus membrane fusion posit that receptor binding to the attachment glycoprotein (G, H, or HN) triggers a conformational cascade in the fusion protein (F). Such F-triggering results in fusion peptide (FP) exposure, which involves formation of a pre-hairpin intermediate and subsequent six-helix bundle formation (11). The energy released upon refolding into the stable six-helix bundle ground state is what drives the fusion of the viral and host-cell membranes. These are common functional and structural features responsible for membrane fusion for all enveloped viruses regardless of whether the fusion protein has predominantly trimeric α-helical coiled-coil (Class I), β (Class II), or a combination of α and β (Class III) core structures (12). Important human pathogens such as the HIV, influenza, and various paramyxoviruses have Class I fusion proteins, and their similar structural features point to similar membrane fusion mechanisms (11, 12). Besides sharing trimeric coiled-coil structures, they are synthesized as precursors that are cleaved into a metastable conformation; cleavage generates a new hydrophobic N terminus FP that gets released and inserted into the target cell membrane upon triggering (11, 12). Class I fusion proteins have two heptad repeat regions, HR1 and HR2, at their N and C termini, respectively, that fold up onto each other during six-helix bundle formation to bring about merging of target cell and viral membranes (12). For Paramyxovirus F proteins, the C-terminal HR2 region is generally thought to be pre-formed, but the N-terminal HR1 region is formed only upon F-triggering and FP insertion (11, 13). The formation of this trimeric HR1 core just before six-helix bundle formation, is known as the pre-hairpin intermediate.Despite their common features, viral fusion proteins vary in their detailed structures, triggering factors, and number of viral surface proteins involved. For paramyxoviruses, receptor binding and fusion functions are carried out by two distinct transmembrane proteins (attachment (G, H, or HN) and fusion (F) proteins, respectively), and with few exceptions both are required for membrane fusion. The underlying mechanism of fusion triggering by the attachment protein may vary depending on their use of protein versus carbohydrate receptors (14). For example, we and others have observed an inverse correlation between fusogenicity of the F protein and the avidity of the F/G or F/H interactions for NiV and measles virus (2, 3, 5, 15, 16), both of which use protein-based receptors; however, for Newcastle disease virus, a glycan-using Paramyxovirus, there seems to be a direct correlation between fusogenicity and the avidity of F/HN interactions (8).For the paramyxoviruses, the early steps in the fusion cascade, particularly how H/HN “triggers” F, are not well understood, and the region(s) in H/HN responsible for F triggering remains unclear, although the stalk domain of H/HN appears to be important for F triggering or for interaction with F (5–8). For NiV, the G attachment glycoprotein binds either the ephrinB2 (B2) or ephrinB3 (B3) protein receptors (17–19), but it is not known how receptor engagement induces G to undergo the allosteric changes involved in triggering F. However, by homology to H or HN, it is likely that the stalk domain in NiV-G is also involved in F-triggering (20). Here we analyze the early steps in the fusion cascade for NiV and identify a specific region in NiV-G distinct from the receptor binding site that is involved in 1) B2-induced changes that trigger FP exposure in F, 2) modulating the avidity of F/G interactions resulting in displacement of F from G, and 3) transducing receptor-induced membrane fusion. Our results offer testable hypotheses as to whether this model of fusion cascade holds true for other paramyxoviruses that use protein-based receptors.     

Expression of fungal cellulase gene in <Emphasis Type="Italic">Lactococcus lactis</Emphasis> to construct novel recombinant silage inoculants

The facultative anaerobic bacterium Lactococcus lactis has been used as a host for expression of a gene isolated from the anaerobic rumen fungus Neocallimastix sp. The coding region of the cellulase gene was obtained from the fungus with the aid of polymerase chain reaction amplification. The gene was then transformed into pCT vector system and the constructed recombinant plasmid was introduced into two L. lactis strains (IL403 and MG1363) by electroporation. The gene encoding the fungal originated cellulase was expressed in both strains successfully although the expression level was relatively lower in comparison with the original enzyme activity. Genetically modified L. lactis strains were used as silage inoculants for pre-biodegradation of the plant biomass during ensiling. That treatment resulted in a notable reduction of the acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents of the plant biomass used as silage material. Inoculation with recombinant strain IL1043 resulted in 4.8 and 9.7 % decrease in NDF and ADF contents, respectively while the inoculation of silage with strain MG1363 decreased the ADF content by >5 %.     

Characterization of Genetic Diversity in Populations of Cultivated and Wild Safflower Species in the Genus Carthamus L. from Turkey as Revealed by ISSR

Biology Bulletin - The aims of this study are to investigate the genetic diversity, the population structure, and the genetic differentiation within and among the populations in the species and...     

A Mechanistic Paradigm for Broad-Spectrum Antivirals that Target Virus-Cell Fusion

LJ001 is a lipophilic thiazolidine derivative that inhibits the entry of numerous enveloped viruses at non-cytotoxic concentrations (IC₅₀≤0.5 µM), and was posited to exploit the physiological difference between static viral membranes and biogenic cellular membranes. We now report on the molecular mechanism that results in LJ001''s specific inhibition of virus-cell fusion.The antiviral activity of LJ001 was light-dependent, required the presence of molecular oxygen, and was reversed by singlet oxygen (¹O₂) quenchers, qualifying LJ001 as a type II photosensitizer. Unsaturated phospholipids were the main target modified by LJ001-generated ¹O₂. Hydroxylated fatty acid species were detected in model and viral membranes treated with LJ001, but not its inactive molecular analog, LJ025. ¹O₂-mediated allylic hydroxylation of unsaturated phospholipids leads to a trans-isomerization of the double bond and concurrent formation of a hydroxyl group in the middle of the hydrophobic lipid bilayer. LJ001-induced ¹O₂-mediated lipid oxidation negatively impacts on the biophysical properties of viral membranes (membrane curvature and fluidity) critical for productive virus-cell membrane fusion. LJ001 did not mediate any apparent damage on biogenic cellular membranes, likely due to multiple endogenous cytoprotection mechanisms against phospholipid hydroperoxides.Based on our understanding of LJ001''s mechanism of action, we designed a new class of membrane-intercalating photosensitizers to overcome LJ001''s limitations for use as an in vivo antiviral agent. Structure activity relationship (SAR) studies led to a novel class of compounds (oxazolidine-2,4-dithiones) with (1) 100-fold improved in vitro potency (IC₅₀<10 nM), (2) red-shifted absorption spectra (for better tissue penetration), (3) increased quantum yield (efficiency of ¹O₂ generation), and (4) 10–100-fold improved bioavailability. Candidate compounds in our new series moderately but significantly (p≤0.01) delayed the time to death in a murine lethal challenge model of Rift Valley Fever Virus (RVFV). The viral membrane may be a viable target for broad-spectrum antivirals that target virus-cell fusion.     

The very rare and little‐known fishes along the coasts of Izmir (Aegean Sea,Turkey) in the past 40 years (1969–2008)

The objective of this study was to document the frequency of occurrence of very rare fish species as well as to note the changes in diversity over time. Fish species recorded fewer than five times over the past 40 years (1969–2008) from the coasts of Izmir (central Aegean Sea) were included in the account and considered as being very rare. The records are listed chronologically. Fish species recently recorded in the area for the first time are also included. Changes in qualitative and quantitative composition of the ichthyofauna along the coasts of Izmir are also discussed.     

The potential usage of caffeic acid phenethyl ester (CAPE) against chemotherapy-induced and radiotherapy-induced toxicity

Protection of the patients against the side effects of chemotherapy and radiotherapy regimens has attracted increasing interest of clinicians and practitioners. Caffeic acid phenethyl ester (CAPE), which is extracted from the propolis of honeybee hives as an active component, specifically inhibits nuclear factor κB at micromolar concentrations and show ability to stop 5-lipoxygenase-catalysed oxygenation of linoleic acid and arachidonic acid. CAPE has antiinflammatory, antiproliferative, antioxidant, cytostatic, antiviral, antibacterial, antifungal and antineoplastic properties. The purpose of this review is to summarize in vivo and in vitro usage of CAPE to prevent the chemotherapy-induced and radiotherapy-induced damages and side effects in experimental animals and to develop a new approach for the potential usage of CAPE in clinical trial as a protective agent during chemotherapy and radiotherapy regimens.