Phosphodiester Amidates of Unsaturated Nucleoside Analogues as Anti-HIV Agents

Abstract

Lipophilic phosphodiester L-alaninates of acyclic unsaturated nucleoside analogues 1d, 1e, 2d, 2e, 3d, 3e, 4d and 5d were prepared and their antiretroviral activity was examined in ATH8 cell culture infected with HIV-1. A possible mechanism of action of these analogues is discussed.     

Per-operative stent placement in the right pulmonary artery; a hybrid technique for the management of pulmonary artery branch stenosis at the time of pulmonary valve replacement in adult Fallot patients

After having undergone surgical correction at an early age, many patients with tetralogy of Fallot develop long-term complications including progressive pulmonary regurgitation and peripheral pulmonary stenosis. A high percentage of these patients need to undergo a second operation in their adolescence or early adulthood. If simultaneous treatment of both pulmonary regurgitation and peripheral pulmonary stenosis is warranted, a complete surgical approach has several disadvantages. We describe four cases of Fallot patients with severe pulmonary regurgitation and peripheral pulmonary stenosis who were treated using a hybrid approach involving surgical implantation of a pulmonary homograft and peroperative stenting of the pulmonary artery.     

Corrosion behaviour, metal release and biocompatibility of implant materials coated by TiO2-sol gel chemistry]

Alloys based on titanium or cobalt have been used as implant materials for decades with good success. Because of their natural oxide layer these alloys reveal good corrosion behaviour. In contact with physiological solution metal release takes place, which can cause inflammation. Coatings can improve the corrosion behaviour. In this study Ti6Al4V and Co28Cr6Mo alloys, which are frequently used as implant materials, were tested. Polished discs of these alloys and polished discs, which were coated with TiO2-layers by sol-gel chemistry, were compared regarding their corrosion behaviour and metal ion releasing. The releasing of Al, V, Ti, Co, Cr and Mo was quantified by ICP-MS analysis. The TiO2-coating reduced the release of all ions except of the Al-ion. Both alloys showed a deviating kinetic of ion releasing. In addition, cell response (cell vitality, cell proliferation, endothelial marker CD31 and actin allocation) of osteoblasts and endothelial cells were investigated.     

Subcellular volumes and metabolite concentrations in barley leaves

Metabolite concentrations in subcellular compartments from mature barley (Hordeum vulgare L. cv. Apex) leaves after 9 h of illumination and 5 h of darkness were determined by nonaqueous fractionation and by the stereological evaluation of cellular and subcellular volumes from light and electron micrographs. Twenty one-day-old primary leaves of barley with a total leaf volume of 902 μL per mg chlorophyll were found to be composed of 27% epidermis, 42% mesophyll cells, 6% veins, 4.5% apoplast and 23% gas space. While in epidermal cells 99% of the volume was occupied by the vacuole, mesophyll cells with an average volume of 31.3 pL consisted of 23 pL (73%) vacuole, 4.6 pL (19%) chloroplasts, 2.06 pL (6,7%) cytosol (including smaller organelles and vesicles), 0.34 pL (1%) mitochondria and 107 fL (0.34%) nucleus. The differences between leaves harvested after 9 h of illumination and after 5 h of darkness were in the size of the stromal compartment and the starch grains therein. Subcellular metabolite concentrations were calculated from the compartmental volumes and metabolite contents of the compartments as determined by nonaqueous fractionation. The amino-acid concentrations in stroma and cytosol were rather similar after 9 h of illumination and 5 h of darkness. In contrast, the vacuolar amino-acid concentrations were about one order of magnitude lower than the stroma and cytosol values, and there was a slight increase in concentration after 5 h of darkness.     

Lutein epoxide cycle, light harvesting and photoprotection in species of the tropical tree genus Inga

Dynamics and possible function of the lutein epoxide (Lx) cycle, that is, the reversible conversion of Lx to lutein (L) in the light-harvesting antennae, were investigated in leaves of tropical tree species. Photosynthetic pigments were quantified in nine Inga species and species from three other genera. In Inga , Lx levels were high in shade leaves (mostly above 20 mmol mol⁻¹ chlorophyll) and low in sun leaves. In Virola surinamensis , both sun and shade leaves exhibited very high Lx contents (about 60 mmol mol⁻¹ chlorophyll). In Inga marginata grown under high irradiance, Lx slowly accumulated within several days upon transfer to deep shade. When shade leaves of I. marginata were briefly exposed to the sunlight, both violaxanthin and Lx were quickly de-epoxidized. Subsequently, overnight recovery occurred only for violaxanthin, not for Lx. In such leaves, containing reduced levels of Lx and increased levels of L, chlorophyll fluorescence induction showed significantly slower reduction of the photosystem II electron acceptor, Q _A, and faster formation as well as a higher level of non-photochemical quenching. The results indicate that slow Lx accumulation in Inga leaves may improve light harvesting under limiting light, while quick de-epoxidation of Lx to L in response to excess light may enhance photoprotection.     

Effect of pressure on islet amyloid polypeptide aggregation: revealing the polymorphic nature of the fibrillation process

Type II diabetes mellitus is a disease which is characterized by peripheral insulin resistance coupled with a progressive loss of insulin secretion that is associated with a decrease in pancreatic islet beta-cell mass and the deposition of amyloid in the extracellular matrix of beta-cells, which lead to islet cell death. The principal component of the islet amyloid is a pancreatic hormone called islet amyloid polypeptide (IAPP). High-pressure coupled with FT-IR spectroscopic and AFM studies were carried out to elucidate further information about the aggregation pathway as well as the aggregate structures of IAPP. To this end, a comparative fibrillation study of IAPP fragments was carried out as well. As high hydrostatic pressure (HHP) is acting to weaken or even prevent hydrophobic self-organization and electrostatic interactions, application of HHP has been used as a measure to reveal the importance of these interactions in the fibrillation process of IAPP and its fragments. IAPP preformed fibrils exhibit a strong polymorphism with heterogeneous structures, a large population of which are rather sensitive to high hydrostatic pressure, thus indicating a high percentage of ionic and hydrophobic interactions and loose packing of these species. Conversely, fragments 1-19 and 1-29 are resistant to pressure treatment, suggesting more densely packed aggregate structures with less void volume and strong cooperative hydrogen bonding. Furthermore, the FT-IR data indicate that fragment 1-29 has intermolecular beta-sheet conformational properties different from those of fragment 1-19, the latter exhibiting polymorphic behavior with more disordered structures and less strongly hydrogen bonded fibrillar assemblies. The data also suggest that hydrophobic interactions and/or less efficient packing of amino acids 30-37 region leads to the marked pressure sensitivity observed for full-length IAPP.     

Complete degradation of carbohydrate to carbon dioxide and methane by syntrophic cultures of Acetobacterium woodii and Methanosarcina barkeri

Methanosarcina barkeri (strain MS) grew and converted acetate to CO₂ and methane after an adaption period of 20 days. Growth and metabolism were rapid with gas production being comparable to that of cells grown on H₂ and CO₂. After an intermediary growth cycle under a H₂ and CO₂ atmosphere acetateadapted cells were capable of growth on acetate with formation of methane and CO₂. When acetate-adapted Methanosarcina barkeri was co-cultered with Acetobacterium woodii on fructose or glucose as substrate, a complete conversion of the carbohydrate to gases (CO₂ and CH₄) was observed.Abbreviation CMC carboxymethyl cellulose     

Perturbation of the mutated EGFR interactome identifies vulnerabilities and resistance mechanisms

We hypothesized that elucidating the interactome of epidermal growth factor receptor (EGFR) forms that are mutated in lung cancer, via global analysis of protein–protein interactions, phosphorylation, and systematically perturbing the ensuing network nodes, should offer a new, more systems‐level perspective of the molecular etiology. Here, we describe an EGFR interactome of 263 proteins and offer a 14‐protein core network critical to the viability of multiple EGFR‐mutated lung cancer cells. Cells with acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) had differential dependence of the core network proteins based on the underlying molecular mechanisms of resistance. Of the 14 proteins, 9 are shown to be specifically associated with survival of EGFR‐mutated lung cancer cell lines. This included EGFR, GRB2, MK12, SHC1, ARAF, CD11B, ARHG5, GLU2B, and CD11A. With the use of a drug network associated with the core network proteins, we identified two compounds, midostaurin and lestaurtinib, that could overcome drug resistance through direct EGFR inhibition when combined with erlotinib. Our results, enabled by interactome mapping, suggest new targets and combination therapies that could circumvent EGFR TKI resistance.     

The Molecular and Structural Characterization of Two Vitellogenins from the Free-Living Nematode Oscheius tipulae

This paper describes the purification of yolk proteins, which are important for the reproduction of egg-laying animals, and the structural characterization of two vitellogenins, VT1 and OTI-VIT-6, of the nematode Oscheius tipulae. O. tipulae is an alternative model organism to its relative, the widely used Caenorhabditis elegans, and is a good model to understand reproduction in insect parasitic nematodes of the genus Heterorhabditis. The native purified O. tipulae vitellogenin is composed of three polypeptides (VT1, VT2 and VT3), whereas in C. elegans, vitellogenin is composed of four polypeptides. The gene (Oti-vit-1) encoding yolk polypeptide VT1 has been recently identified in the genome of O. tipulae. Immunoblotting and N-terminal sequencing confirmed that VT1 is indeed coded by Oti-vit-1. Utilizing the same experimental approaches, we showed that the polypeptides VT2 and VT3 are derived from the proteolytic processing of the C- and N-terminal portions of the precursor OTI-VIT-6, respectively. We also showed that the recombinant polypeptide (P40), corresponding to the N-terminal sequence of OTI-VIT-6, preferentially interacts with a 100-kDa polypeptide found in adult worm extracts, as we have previously shown for the native vitellins of O. tipulae. Using the putative nematode vitellogenin amino acid sequences available in the UniProtKB database, we constructed a phylogenetic tree and showed that the O. tipulae vitellogenins characterized in this study are orthologous to those of the Caenorhabditis spp. Together, these results represent the first structural and functional comparative study of nematode yolk proteins outside the Caenorhabditis genus and provide insight into the evolution of these lipoproteins within the Nematode Phylum.     

Studies on Galalpha3-binding proteins: comparison of the glycosphingolipid binding specificities of Marasmius oreades lectin and Euonymus europaeus lectin

The carbohydrate binding preferences of the Galalpha3Galbeta4 GlcNAc-binding lectins from Marasmius oreades and Euonymus europaeus were examined by binding to glycosphingolipids on thin-layer chromatograms and in microtiter wells. The M. oreades lectin bound to Galalpha3-terminated glycosphingolipids with a preference for type 2 chains. The B6 type 2 glycosphingolipid (Galalpha3[Fucalpha2]Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) was preferred over the B5 glycosphingolipid (Galalpha3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer), suggesting that the alpha2-linked Fuc is accommodated in the carbohydrate binding site, providing additional interactions. The lectin from E. europaeus had broader binding specificity. The B6 type 2 glycosphingolipid was the best ligand also for this lectin, but binding to the B6 type 1 glycosphingolipid (Galalpha3[Fucalpha2]Galbeta3GlcNAcbeta3Galbeta4Glcbeta1Cer) was also obtained. Furthermore, the H5 type 2 glycosphingolipid (Fucalpha2Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer), devoid of a terminal alpha3-linked Gal, was preferred over the the B5 glycosphingolipid, demonstrating a significant contribution to the binding affinity by the alpha2-linked Fuc. The more tolerant nature of the lectin from E. europaeus was also demonstrated by the binding of this lectin, but not the M. oreades lectin, to the x2 glycosphingolipid (GalNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) and GlcNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer. The A6 type 2 glycosphingolipid (GalNAcalpha3[Fucalpha2]Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) and GalNAcalpha3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1-Cer were not recognized by the lectins despite the interaction with B6 type 2 glycosphingolipid and the B5 glycosphingolipid. These observations are explained by the absolute requirement of a free hydroxyl in the 2-position of Galalpha3 and that the E. europaea lectin can accommodate a GlcNAc acetamido moiety close to this position by reorienting the terminal sugar, whereas the M. oreades lectin cannot.