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En el presente estudio se analizó una empresa del ramo de la manufactura del área Metropolitana de Monterrey, que tiene su planta en el municipio de Ciénega de Flores Nuevo León, la cual centra su producción en equipos de refrigeración comercial. Esta investigación se compone de cinco capítulos los cuales se encuentran detallados de la siguiente forma. El primer capítulo se presenta una introducción al tema investigado, además de planteamiento y declaración del problema, propósito y objetivos de investigación, limitaciones y delimitaciones, importancia y justificación del estudio, supuestos básicos. En el segundo capítulo se muestra una revisión de literatura relevante que se relaciona con los objetivos de la investigación. En el tercer capítulo se presenta la metodología que se siguió en este estudio, la definición de términos relacionados con el tema, la elaboración y forma de aplicación de cuestionarios, además se describe la población objeto del estudio y se explica el diseño o estrategia de investigación y la construcción del instrumento necesario para el análisis de datos. En el capítulo cuarto se analizan y discuten los datos, contiene los principales hallazgos así como, los resultados obtenidos en relación con los objetivos de esta investigación. En el capítulo quinto se presenta las conclusiones y las recomendaciones que se obtuvieron de este, trabajo, para concluir se presentan las Referencias y los anexos, correspondientes.

African swine fever virus (ASFV) CD2v protein is believed to be involved in virulence enhancement, viral hemadsorption, and pathogenesis, although the molecular mechanisms of the function of this viral protein are still not fully understood. Here we describe that CD2v localized around viral factories during ASFV infection, suggesting a role in the generation and/or dynamics of these viral structures and hence in disturbing cellular traffic. We show that CD2v targeted the regulatory trans-Golgi network (TGN) protein complex AP-1, a key element in cellular traffic. This interaction was disrupted by brefeldin A even though the location of CD2v around the viral factory remained unchanged. CD2v-AP-1 binding was independent of CD2v glycosylation and occurred on the carboxy-terminal part of CD2v, where a canonical di-Leu motif previously reported to mediate AP-1 binding in eukaryotic cells, was identified. This motif was shown to be functionally interchangeable with the di-Leu motif present in HIV-Nef protein in an AP-1 binding assay. However, we demonstrated that it was not involved either in CD2v cellular distribution or in CD2v-AP-1 binding. Taken together, these findings shed light on CD2v function during ASFV infection by identifying AP-1 as a cellular factor targeted by CD2v and hence elucidate the cellular pathways used by the virus to enhance infectivity.

During the recent past years, tremendous efforts have been made to establish enantioselective routes for the preparation of enantiomerically pure compounds due to their importance in the pharmaceutical, agricultural, and food industries. This is reflected in the fact that the sales of single-enantiomer small-molecule drugs has reached c. US $10 billion in 2002.1 Moreover, the FDA has become increasingly reluctant to permit the introduction of additional racemic drugs, as these therapies are by definition saddled with 50% of chemical ballast.2 Enzymes are nowadays widely recognized among the most active and selective catalysts for the preparation of optically active compounds.3 Some of the factors that account for this popularity are (1) They are chemo-, regio-, and stereoselective, and environmentally friendly. (2) Because of the mild conditions under which they operate, enzymatic reactions are affected to a lesser extent by side reactions (viz. isomerization, racemization, epimerization, and rearrangement of molecules) as compared to nonenzymatic processes. Nevertheless, organic chemists have been traditionally reluctant to employ biocatalysts in their syntheses. This is mainly because, in their natural form, most of the enzymes are very sensitive catalysts that exert their activity mainly in aqueous solution. Moreover, their handling requires some biochemistry knowledge. However, some recent advances carried out in the biocatalysis field have “approached” enzymes to organic synthesis: (a) They can operate in nonaqueous media accepting a broad range of substrates;4 (b) immobilization techniques increase their stability and simplify their handling.5 Thus, many enzymes can now be acquired and used as any other chemical., Stereoselective biotransformations can be grouped into two main different classes: asymmetric synthesis and kinetic resolution of racemic mixtures (KR). Conceptually, they differ from each other in the fact that while asymmetric synthesis implies the formation of one or more chirality elements in a substrate, a KR is based on a transformation, which, subsequently, makes easier the separation of the two enantiomers of the racemic substrate. This fact involves a practical difference: in a kinetic resolution only half of the starting material is used. When only one enantiomer of a substrate is required this fact constitutes a disadvantage of KRs and different approaches have been developed to overcome this limitation.6 The one on which more attention has been recently paid is the dynamic KR7 and consists of carrying out an in situ continuous racemization of the substrate, so that, theoretically, all of the racemic starting material can be used for transformation into one enantiomer. Nevertheless, many substrates employed in enzyme-catalyzed kinetic resolutions are not liable to undergo racemization., The desymmetrization of symmetric compounds consists of a modification that eliminates one or more elements of symmetry of the substrate. If the symmetry elements that preclude chirality are eliminated, enantioselectivity can be achieved.8 Enantioselective enzymatic desymmetrizations (EEDs) belong to the field of asymmetric synthesis and, accordingly, a maximum yield of 100% can be attained.9 For this reason, they constitute a very interesting alternative to KRs for the preparation of optically active compounds, which is reflected in the increasing number of enzymatic desymmetrizations applied to synthesis published in the literature during the recent past years. This review deals with the developments made in the use of biocatalysts for the desymmetrization of meso and prochiral compounds, especially from 1999 on. It is structured according to a synthetic rather than a biocatalytic point of view and, as a rule of thumb, only those examples useful from a synthetic point of view are included, i.e., EEDs that constitute or can constitute a key step in a synthetic route, or aid to rationalize either the substrate specificity of an enzyme or the desymmetrization of a certain class of compounds. Accordingly, important parameters to which attention has been paid are enantioselectivity and the yield of the EED, which should be higher than 50% so that the desymmetrization implies a clear advantage over KRs. Nevertheless, exceptions can be made on the basis of novelty and difficulty of obtaining a compound by other means.

The molecular basis of drug action is often not well understood. This is partly because the very abundant and diverse information generated in the past decades on drugs is hidden in millions of medical articles or textbooks. Therefore, we developed a one-stop data warehouse, SuperTarget that integrates drug-related information about medical indication areas, adverse drug effects, drug metabolization, pathways and Gene Ontology terms of the target proteins. An easy-to-use query interface enables the user to pose complex queries, for example to find drugs that target a certain pathway, interacting drugs that are metabolized by the same cytochrome P450 or drugs that target the same protein but are metabolized by different enzymes. Furthermore, we provide tools for 2D drug screening and sequence comparison of the targets. The database contains more than 2500 target proteins, which are annotated with about 7300 relations to 1500 drugs; the vast majority of entries have pointers to the respective literature source. A subset of these drugs has been annotated with additional binding information and indirect interactions and is available as a separate resource called Matador. SuperTarget and Matador are available at http://insilico.charite.de/supertarget and http://matador.embl.de.