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Brunow, Germany

Kiep L.,Private Laboratory | Gohl M.,University of Bayreuth | Schmidt J.,Leibniz Institute of Plant Biochemistry | Seifert K.,University of Bayreuth
Drug Research

Metabolism studies with selected test substances have shown that a model on the basis of the incubated hen's egg is suitable as a supplement to animal experimentation. Because of its 3,4-dimethoxyphenyl structure veratric acid (3,4-dimethoxybenzoic acid), a known human metabolite of mebeverine, was chosen as model substance for the present investigations and the parent compound as well as 4-hydroxy-3-methoxybenzoic acid were identified as main metabolites. The absence of 3-hydroxy-4-methoxybenzoic acid lets conclude that the O-demethylation takes place exclusively at the p-methoxyl function. In addition, 3,3',4,4'-tetramethoxy-l-ornithuric acid (2,5-bis-(3,4-dimethoxybenzoylamino)pentanoic acid) and its O-desmethyl derivative could be characterized as further metabolites. So far an amino acid conjugate has not been described after veratric acid administration in a vertebrate. There were no indications for the appearance of 3,4-dihydroxybenzoic acid in the veratric acid metabolism. This was confirmed by corresponding studies having the isomeric guaiacol acids as precursor. Furthermore, it could be proved that in ovo the O-methylation of 3,4-dihydroxybenzoic acid occurs regioselective at the m-hydroxyl group. The results which broaden the knowledge on the metabolic fate of veratric acid are discussed in comparison with those in mammals. The metabolites were identified by GC-MS, ESI-HRMS and LC/ESI-MS/MS. The structure of the synthesized reference substance was confirmed by MS, 1H and 13C NMR spectral data. © Georg Thieme Verlag KGStuttgart · New York. Source

Westermeier R.,Austral University of Chile | Patino D.J.,Austral University of Chile | Muller H.,Private Laboratory | Muller D.G.,University of Konstanz
Journal of Applied Phycology

Macrocystis is an important marine resource in Chile, with severe problems of over-exploitation. Our study describes genetic materials and techniques for a further improvement of laboratory-based mariculture. For a systematic hybridization program we have selected one pair (cultivar) of gametophytes with favorable somatic and reproductive characteristics from each of seven localities in southern Chile. Sporophytes from all 49 crosses were grown for 10 weeks to seedling size. We report here that sporophytes from sympatric parents (intra-cultivar matings) grow to different length, depending on the locality and, importantly, that sporophytes from several inter-cultivar crossings show superior growth, suggesting heterosis with symmetric or asymmetric reciprocity. The genetic materials and techniques described here, together with our newly developed standardized seedling production protocols now available, constitute a significant step towards domestication of Macrocystis in analogy to terrestrial agriculture. © Springer Science+Business Media B.V. 2009. Source

Villalon G.C.,Private Laboratory
Journal of Chemical Education

The modification of a plastic bottle to be adapted to an electronic digital buret is described. A hole is made at the bottom of the bottle that allows a little container with the titrant to be placed inside the bottle. Determinations with relatively small volume of titrant can be made with this system. This design is especially useful for titrations with expensive or unstable reagents, thus, saving costs and space storage in the laboratory. © 2013 The American Chemical Society and Division of Chemical Education, Inc. Source

Cruz G.,Private Laboratory
Journal of Chemical Education

The use of boric acid in the Kjeldahl determination of nitrogen is a variant of the original method widely applied in many laboratories all over the world. Its use is recommended by control organizations such as ISO, IDF, and EPA because it yields reliable and accurate results. However, the chemical principles the method is based on are not detailed in most analytical textbooks, perhaps because the nature of boric acid is not known in depth. To introduce the reader or student to the chemistry of boric acid, this article first describes the differences in acid-base behavior of concentrated and diluted boric acid by simple calculations and experimental pH measurements. Next, polyborate structures and their respective dissociation constants are shown to explain the differences found in previous pH measurements. In the second part of the article, the determination of ammonia with HCl is made in concentrated and diluted boric acid to reproduce the final Kjeldahl titration when two different volumes of ammonia distillate are collected. From the previous information, the apparently paradoxical results of the titration curves are explained in a qualitative manner. The third part consists of a study of systematic errors produced when colored indicators are used in the final Kjeldahl titration in concentrated and diluted boric, respectively. © 2013 The American Chemical Society and Division of Chemical Education, Inc. Source

Minasyan H.A.,Private Laboratory
International Reviews of Immunology

Leukocytes can't perform phagocytosis in blood stream. Blood velocity prevents phagocytosis because there is no time for leukocyte to recognize and catch bacteria. Bloodstream clearance from pathogens is performed by erythrocytes. During motion in bloodstream erythrocytes become charged by triboelectric effect. This charge attracts bacteria and fixes them on the surface of erythrocyte, then bacteria are engulfed and killed by hemoglobin oxygen. In bloodstream, leukocyte thin-wrinkled elastic membrane can't be charged by triboelectric effect and so leukocyte can't catch bacteria by means of electrostatic attraction force. Leukocytes engulf and kill bacteria out of blood circulatory system: in tissues, lymph nodes, slow velocity lymph, etc. Erythrocyte and leukocyte are bactericidal partners: the first kills bacteria in bloodstream, the second kills them locally, out of blood circulation. © 2014 Informa Healthcare USA, Inc. Source

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