1-O-benzyl-2-O-methyl-rac-glycerol: a key intermediate for synthesis of ether glycerolipids.

A new scheme for synthesis of saturated 1-O-alkyl-2-O-methyl-rac-glycerolipids is described. The reductive cleavage of 2-O-methyl-1,3-O,O-benzylideneglycerol with BH3.THF complex leads to 1-O-benzyl-2-O-methyl-rac-glycerol, which is a key in intermediate for the facile preparation of 1-O-alkyl-2-O-methyl-rac-glycerol and derivatives.     

Laser-Driven Hybridization of a Surface Plasmon Resonance Collective Mode in a Monolayer of Silver Nanoparticles

Plasmonics - Laser-driven hybridization of a collective surface plasmon mode of a monolayer of silver nanoparticles has been studied as a function of irradiation power density. Two collective...     

Polyphenol-induced dissociation of various amyloid fibrils results in a methionine-independent formation of ROS

Fibrillization of amyloid polypeptides is accompanied by formation of reactive oxygen species (ROS), which, in turn, is assumed to further promote amyloid-related pathologies. Different polyphenols, all of which are established antioxidants, cause dissociation of amyloid fibrils. This study addresses the latter, poorly understood process. Specifically, we have investigated the dissociation of Abeta(42) fibrils by six different polyphenols, using electron microscopy and spectrofluorometric analysis. Simultanously, we have monitored the production of ROS using electron spin resonance (ESR) and the commercially available peroxide assay kit. Using the same methods we found that curcumin, one of the most potent destabilizing agents of Abeta(42), induced dissociation of fibrils of other amyloid polypeptides [Abeta(40), Abeta(42)Nle35, islet amyloid polypeptide and a fragment of alpha-synuclein]. When the solution contained traces of transition metal, all the dissociation reactions were accompanied by ROS formation, independent of the presence of a methionine residue. Kinetic studies show that the formation of ROS lags behind dissociation, indicating that if casual relationship exists between these two processes, then ROS formation may be considered a consequence and not a cause of dissociation. These findings open new avenues in amyloid research that will be required to gain further understanding of our results and of their implications.     

Lipid peroxidation in the presence of albumin, inhibitory and prooxidative effects

Oxidative modifications of LDL are involved in atherogenesis. Previously we have developed a simple assay to evaluate the susceptibility of lipids to copper-induced peroxidation in the relatively natural milieu of unfractionated serum in the presence of excess citrate. Based on our previous results we have proposed that the inducer of peroxidation in our optimized assay is a copper-citrate complex. Recent investigations indicate that under certain conditions a copper-albumin complex may induce peroxidation of ascorbate. Two different complexes may be formed in albumin-containing systems (e.g. serum) namely 1:1 and 2:1 copper-albumin complexes. The aim of the present work was to evaluate the possibility that at least one of these complexes may be responsible for the induction of peroxidation of lipids in lipidic systems containing copper and albumin, including our optimized assay. Towards this end, we have investigated the dependence of copper-induced peroxidation on the concentration of added albumin in lipidic systems in the absence and presence of citrate. In all the systems investigated in this study (PLPC liposomes, LDL, HDL and mixtures of HDL and LDL) we found that at low concentrations of free copper (e.g. in the presence of excess citrate) the 2:1 copper-albumin complex is redox-active and that this complex is the major contributor to the initiation of lipid peroxidation in these systems and in our optimized assay. The possible relevance of the induction of peroxidation in vivo by the latter complex has yet to be studied. *This work was performed in partial fulfillment of the requirements for a Ph.D. degree of Dorit Samocha-Bonet, Sackler Faculty of Medicine, Tel-Aviv University, Israel.     

Bovine viral diarrhea viruses differentially alter the expression of the protein kinases and related proteins affecting the development of infection and anti-viral mechanisms in bovine monocytes

Using a proteomics approach, we evaluated the effect of cytopathic (cp), and non-cytopathic (ncp) bovine viral diarrhea viruses (BVDV) on the expression of protein kinases and related proteins in bovine monocytes. Proteins were isolated from membrane and cytosolic fractions with the differential detergent fractionation (DDF) method and identified with 2D-LC ESI MS(2). Of approximately 10,000 proteins identified, 378 proteins had homology with known protein kinases or related proteins. Eighteen proteins involved in cell differentiation and activation, migration, anti-viral mechanisms (interferon/apoptosis), biosynthesis, sugar metabolism and oncogenic transformation were significantly altered in BVDV-infected monocytes compared to the uninfected controls. Six proteins, mostly related to cell migration, anti-viral mechanisms, sugar metabolism and possibly tumor resistance were differentially expressed between the ncp and cp BVDV-infected monocytes. Particularly, the expression of the receptor of activated C kinase (RACK), of pyridoxal kinase (PK), diacyglycerol kinase (DGK) and Brutons tyrosine kinase (BTK) was decreased in monocytes infected with cp BVDV compared to ncp BVDV, possibly contributing to the cytopathic effect of the virus. This and other findings are discussed in view of the possible role the identified proteins play in the development of viral infection and oncogenic transformation of cells.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 4. The morphological and ultrastructural changes in the liver of rats]

A study was made of the morphological and ultrastructural changes in hepatic tissue of rats lived within the Chernobyl accident zone during the period of 6 to 25 months. Considerable nonspecific changes in hepatocytes (fatty, vacuolar and parenchymatous degeneration, and hepatocyte necrobiosis) were seen throughout the entire period of observation. Coagulation necrosis of certain hepatocytes, Kupffer and endothelial cells, and the development of microcholangiomas by the end of the second year were the most characteristic alterations.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 3. The morphological and ultrastructural changes in the lungs of rats]

The morphological and ultrastructural changes revealed in the lungs of rats kept within the Chernobyl accident zone during the period of 6 to 24 months were shown to be uniform and multicomponent. The changes were found both in the respiratory and the vascular connective tissue. The inflammatory processes occurred with formation of pneumonic foci, hypo- and disatelectasis, emphysematous changes, impairment of interalveolar septa, and connective tissue cell proliferation. In the lung tissue, focal and diffuse lymphoid proliferates and, at later stages, lymphomatous changes were revealed.     

The effect of the binding of the antigenic determinant of tetrodotoxin-sensitive protein on the phytohemagglutinin-induced proliferative response of the mononuclear cells in mouse spleen]

Mammalian brain-derived "tetrodotoxin-sensitive protein" has been shown to share an epitope with as yet unidentified structure of the human and rodent lymphocyte surface. Previously obtained observations that a monoclonal antibody to this epitope induces a proliferative response of murine splenic mononuclear cells are confirmed. However, this antibody fails to modify the phytohemagglutinin-induced response. Moreover, lectin with submitogenic concentration inhibited the antibody-induced response provided that monocytes were present in the culture. The antibody-induced proliferation appeared to be less monocyte-dependent than the lectin-induced one. Taken together, these findings argue against hypothesis that a lymphocyte structure with epitope of the "tetrodotoxin-sensitive protein" is associated with either T cell receptor for antigen or interleukin-2 receptor.     

Monoclonal antibodies to cytoplasmic tetrodotoxin-sensitive brain protein. Effects of veratrine on binding between antibodies and neuroblastoma cells

The effects were studied of neurotoxins, which modulate the activity of voltagedependent sodium channels, on binding between neuroblastoma cells and monoclonal antibodies to cytoplasmic tetrodotoxin-sensitive protein displaying the properties of tetrodotoxin-sensitive sodium channles when incorporated into the liposomes. Binding between antibodies and the monolayer of viable (unfixed) cells recorded by immunoenzyme testing was found to break down in the presence of veratrine (veratridine). It is postulated that the antibodies obtained bind with an antigenic determinant located at or near the veratrine binding site.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 6, pp. 794–800, November–December, 1988.