Showing papers by "University of Alcalá published in 1981"
TL;DR: The ring transformations of 4H-pyrans into pyridines are reported in this article, which can also be obtained from α-benzoylcinnamonitriles (IX) and cyanoacetamide.
27 citations
TL;DR: The ultrastructure of splenic tissue of non-immunized turtles, Mauremys caspica, shows two areas, namely, the white pulp, which is lymphoid in nature, and the red pulp which is formed by cell cords and sinusoids.
Abstract: The ultrastructure of splenic tissue of non-immunized turtles, Mauremys caspica, shows two areas, namely, the white pulp which is lymphoid in nature, and the red pulp which is formed by cell cords and sinusoids. Between both areas there is always a marginal zone with gaps through which cells leak. In the white pulp, there are two blood vessel types; one with muscled walls, and the other showing thinner walls sheathed by reticular cells. Reticular cells constitute a network where there occur dendritic macrophages, lymphoblasts and small and medium lymphocytes. Mature plasma cells are scarce in the white pulp.
26 citations
TL;DR: This study demonstrates for the first time the presence of mature and developing plasma cells in the spleen of non-immunized ammocoetes of Petromyzon marinus.
Abstract: This study demonstrates for the first time the presence of mature and developing plasma cells in the spleen of non-immunized ammocoetes of Petromyzon marinus. Plasmocytes occur as electron-dense cells with much condensed chromatin and an extensively large developed and dilated rough endoplasmic reticulum. The importance of this finding is emphasized in relation to the evolution of the immune system.
24 citations
TL;DR: In leaf segments of barley (Hordeum vulgare L. cv. Mozoncillo), the cytokinin specificity for retarding the loss of phosphate is different from that of retardingThe loss of chlorophyll.
Abstract: In leaf segments of barley (Hordeum vulgare L. cv. Mozoncillo), the cytokinin specificity for retarding the loss of phosphate is different from that of retarding the loss of chlorophyll. Some cytokinins require the simultaneous application of gibberellins to delay the loss of phosphate. Although both chlorophyll and phosphate losses occur in senescence, they are apparently controlled by cytokinins through different mechanisms.
14 citations
TL;DR: The jugular bodies of adult R. pipiens are plasma cell and antibody-forming organs, whose functional significance is discussed in relation to their ultrastructural organization.
Abstract: The jugular bodies in adult Rana pipiens, are surrounded by a capsule of mesothelium and connective tissue, and their parenchyma consists of cell cords arranged in a sinusoidal network. The cell cords are formed by irregular reticular cells, showing numerous filaments and joined together by zonulae adhaerents. The intercellular spaces are filled by reticular fibres and free cells. These latter are small and medium lymphocytes, lymphoblasts, and developing and mature plasma cells. Additionally, free macrophages, neutrophils and acidophils also occur. Sinusoidal blood vessels show thin walls with numerous filaments and pinocytotic vesicles. They exhibit a discontinuous basement membrane, and tight junctions frequently occur between endothelial cells. Occasionally, lymphatic vessels are found and the innervation is principally vasomotor, although nerve endings appear remarkably near reticular cells and lymphocytes. The jugular bodies of adult R. pipiens are plasma cell and antibody-forming organs, whose functional significance is discussed in relation to their ultrastructural organization.
8 citations
TL;DR: The assignment of relative configurations to the diastereomeric racemates (1R2R, 1S2S) of 1-mesityl-2-methyl-3-phenyl-1-propanol was carried out by studing the chemical shifts induced by Eu(fod)3 an the signal of the Me group in position 2.
7 citations
TL;DR: In this paper, the award of a Research Fellowship (to A.V.) by the Ministerio de Educació and Ciencia (Spain) was presented to the author.
7 citations
TL;DR: In this article, the reaction of Co(η-C 5 H 5 )(CO)I 2 with PEt 3 in the stoichiometry 1 : 1, 1 : 2 or 1 : 3 gave the complexes Co(C 5H5 )(PEt 3 )I 2, [Co(C5H5 ), I 2 ]I and a mixture of CO(CO), I 2 and Co(PET 3 ) 2 I 2, respectively, for the nucleophiles Y − = CN −, N 3 −, MeO −, H
6 citations
TL;DR: In this article, the properties of these compounds are discussed, and the compounds are also produced by treating solutions of (C 6 F 5 ) 2 Co-(dioxane) 2 with CO, but a simultaneous reduction to CO(CO) 4 takes place.
5 citations
5 citations
TL;DR: The ultrastructure of normal and immunized jugular bodies in adult frogs is analyzed to point out new information on these primitive lymphoid organs to show a diminution in PFC response in the jugular body.
Abstract: We have analyzed the ultrastructure of normal and immunized jugular bodies in adult frogs to point out new information on these primitive lymphoid organs. They consist of cell cords arranged in a sinusoidal network. The cell cords are formed by a stroma of reticular cells with intercellular spaces filled by free cells. The free cells consist of small and medium lymphocytes, lymphoblasts and developing and mature plasma cells, and in lesser amounts of free macrophages and granulocytes. After immunizing Rana bermeja with SRBC there is an increase in plasma cells at 7 days correlating with the increase in PFC response and in serum antibody titers. However, at 14 days we have observed a diminution in PFC response in the jugular body. At this time, there occurs an increase in the number of eosinophils accompanied by degranulation. The results are discussed from a functional and phylogenetic view.
TL;DR: In this paper, a mechanism that describes an alternative procedure to the direct product of groups by involving some scalar fields related to the group parameters has been proposed, which may provide a framework for grand unified theories with a minimal increase in the number of fundamental fields required.
Abstract: We propose a mechanism that describes an alternative procedure to the direct product of groups by involving some scalar fields related to the group parameters. In particular, the method may provide a framework for grand unified theories with a minimal increase in the number of fundamental fields required.