Selenium-containing tRNAs from Clostridium sticklandii. Cochromatography of seleno-tRNA I with l-valyl-tRNA

It has been previously shown that Clostridium sticklandii specifically synthesized three readily separable ⁷⁵Se-labeled tRNAs, designated seleno-tRNAs I, II and III, and the partially purified seleno-tRNA II cochromatographed with l-prolyl-tRNA on DEAE-Sephadex A-50 (Chen, C.S. and Stadtman, T.C. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 1403–1407). In the present study a highly purified ⁷⁵Se-labeled tRNA I was obtained by chromatography on benzoylated DEAE-cellulose, DEAE-Sephadex A-50 and Sepharose 4B. The ⁷⁵Se-labeled tRNA I cochromatographed with an l-valine-accepting species on DEAE-Sephadex A-50 and Sepharose 4B. Addition of a 285-fold molar excess of unlabeled l-valine to the l-valine acceptor activity assay mixture markedly decreased the amount of l-[¹⁴C]valine bound to seleno-tRNA I.     

Minor sterols of marine invertebrates 37. Isolation of novel coprostanols and 4α-methyl sterols from the tunicate Ascidia nigra

The complex sterol mixture isolated from $\text{A, nigra}$ was found to contain a low level of Δ⁴-3-keto steroids, 5β-stanols and 4α-methyl sterols in addition to regular (4-demethyl) sterols. The following new marine sterols were isolated and identified using MS and 360 MHz NMR: 5β-cholest-22E-en-3β-ol, 24S-methyl-5β-cholest-22E-en-3β-ol, 24-methylene-5β-cholestan-3β-ol, both epimers at C-24 of 4α-methyl-24-ethyl-5α-cholest-22E-en-3β-ol, 4α, 22ξ, 23ξ-(or 24ξ-)trimethyl-5α-cholest-8(14)-en-3β-ol and (22S, 23S, 24S)-4α-24-dimethyl-22, 23-methylene-5α-cholestan-3β-ol. The latter sterol and 23-demethylgorqosterol have opposite configurations at C-22, C-23, and C-24; the Δ⁸⁽¹⁴⁾ sterol has an unprecedented side chain.     

Experimental study on aggregation of model dipeptide molecules. V. Stereoselective association of leucine dipeptides

Infrared spectroscopy and ¹H nmr have been used to elucidate the association modes of leucine dipeptides in carbon tetrachloride solution. Two stereoselective types of aggregates have been evidenced. Homochiral molecules are associated in oligomeric aggregates and accommodate a β-parallel-like structure which was characterized by x-ray diffraction. Heterochiral molecules are paired in centrosymmetrical dimers; the latter aggregation mode restricted to the dimer stage predominates in racemic solutions. A theoretical model proposed to account for this aggregation process is consistent with the experimental nmr data. Both homo- and heterochiral association constants are estimated from vapor pressure and nmr experiments.     

Étude expérimentale de l'auto-association des molécules modèles dipeptidiques. II. Association stéréosélective des molécules énantiomères

Modes of aggregation fo alanine-, norvaline- and valine-contaiing dpepetides with the general formula R₁? C₁O₁? N₂H₂? CHR₂? C₂O₂? N₃H₃? R₃ have been studied in CCl₄ solution by using infrared and nuclear magnetic resonance spectroscopies. Solutions of the pure L isomer and of the racemic mixture do not give identical data. At a given concentration, the racemic mixtrue is more aggregated than the pure enantiomer, and the difference, negligible in the case of alanine derivative, increases wiht the bulkiness of the side cahin R₂. The results show that a selective interaction takes place between enantiomeric molecules, resulting ina dimer associating tow inverse configurated C₅ conformers. The stabilizaion of this dimer proceeds from two symmetrical and intermolecular H₃ … O₁ hydrogen bondings.     

The influence of insulin on glucose permeability and metabolism of human granulocytes.

Viable human polymorphonuclear leukocytes isolated from peripheral blood were incubated for 1 h at 37 degrees C with variable concentrations of insulin in a saline medium buffered at pH 7.4. The hormone increased glucose consumption by about 40% without influencing the permeability of the membranes to glucose, whose uptake followed a passive diffusion process. The measurement of intermediates localized activation of glycolysis by insulin, down to 0.36 nM, at the phosphofructokinase step. However, the spectrophotometric measurement showed no activation of phosphofructokinase after preincubation with insulin of either intact granulocytes or crude or ultracentrifuged homogenates. The level of cyclic AMP, which is known to activate phosphofructokinase, was not modified by insulin; cyclic GMP did not activate the enzyme in the granulocyte extracts: neither of the two nucleotides can therefore be considered as a direct messenger of the action of insulin on phosphofructokinase. An important fraction of the extra glucose consumed under the influence of insulin was recovered as neither glycogen nor lactate, nor was it oxidized in the Krebs cycle. It might be assumed to have been converted into glycerolipids. However, insulin produced no detectable accumulation of triglycerides and activated neither the pentose phosphate pathway nor oxidative decarboxylation of pyruvate. The fate of the extra glucose consumed under the influence of insulin therefore remains questionable.     

The role of YKL-40 in the pathogenesis of autoimmune diseases: a comprehensive review

YKL-40, a chitinase-3-like protein 1 (CHI3L1) or human cartilage glycoprotein 39 (HC gp-39), is expressed and secreted by various cell-types including macrophages, chondrocytes, fibroblast-like synovial cells and vascular smooth muscle cells. Its biological function is not well elucidated, but it is speculated to have some connection with inflammatory reactions and autoimmune diseases. Although having important biological roles in autoimmunity, there were only attempts to elucidate relationships of YKL-40 with a single or couple of diseases in the literature. Therefore, in order to analyze the relationship between YKL-40 and the overall diseases, we reviewed 51 articles that discussed the association of YKL-40 with rheumatoid arthritis, psoriasis, systemic lupus erythematosus, Behçet disease and inflammatory bowel disease. Several studies showed that YKL-40 could be assumed as a marker for disease diagnosis, prognosis, disease activity and severity. It is also shown to be involved in response to disease treatment. However, other studies showed controversial results particularly in the case of Behçet disease activity. Therefore, further studies are needed to elucidate the exact role of YKL-40 in autoimmunity and to investigate its potential in therapeutics.     

Protective Role of miR-34c in Hypoxia by Activating Autophagy through BCL2 Repression

Hypoxia leads to significant cellular stress that has diverse pathological consequences such as cardiovascular diseases and cancers. MicroRNAs (miRNAs) are one of regulators of the adaptive pathway in hypoxia. We identified a hypoxia-induced miRNA, miR-34c, that was significantly upregulated in hypoxic human umbilical cord vein endothelial cells (HUVECs) and in murine blood vessels on day 3 of hindlimb ischemia (HLI). miR-34c directly inhibited BCL2 expression, acting as a toggle switch between apoptosis and autophagy in vitro and in vivo. BCL2 repression by miR-34c activated autophagy, which was evaluated by the expression of LC3-II. Overexpression of miR-34c inhibited apoptosis in HUVEC as well as in a murine model of HLI, and increased cell viability in HUVEC. Importantly, the number of viable cells in the blood vessels following HLI was increased by miR-34c overexpression. Collectively, our findings show that miR-34c plays a protective role in hypoxia, suggesting a novel therapeutic target for hypoxic and ischemic diseases in the blood vessels.     

Current state and perspectives on erythropoietin production

Erythropoietin is a major regulator of erythropoiesis which maintains the body's red blood cell mass and tissue oxygenation at an optimum level. Recombinant human erythropoietin (rhEPO), which is a widely used therapeutic agent for the treatment of anemia and which represents one of the largest biopharmaceuticals markets, is produced from recombinant Chinese hamster ovary cells. rhEPO is a glycoprotein with complex glycan structure, which is responsible for its therapeutic efficacy, including the in vivo activity and half-life. In order to obtain an optimal and consistent glycoform profile of rhEPO and concurrently maintain a high production yield, various approaches in drug development and cell culture technology have been attempted. Recent advances in rhEPO production are classified into three types: the development of improved rhEPO molecules by protein engineering; improvement of production host cells by genetic engineering; and culture condition optimization by fine control of the production mode/system, process parameters, and culture media. In this review, we focus on rhEPO production strategies as they have progressed thus far. Furthermore, the current status of the market and outlook on rhEPO and its derivatives are discussed.