Diferencias de protección frente al riesgo biológico laboral en relación al sistema preventivo elegido por la empresa / Differences of occupational biohazard protection in relation to preventive system chosen by the company

El objetivo de este trabajo ha sido obtener información sobre el nivel de exposición y protección de los trabajadores a los agentes biológicos laborales en diferentes sectores de actividad valorando sus diferencias en relación al sistema preventivo elegido por las empresas. Se realizó un estudio en el que participaron 590 trabajadores de 59 empresas españolas en las que se pasaron 2 cuestionarios, uno para la empresa y otro para los trabajadores, obteniéndose una muestra definitiva de 518 trabajadores pertenecientes a 51 empresas en las que existía exposición a agentes biológicos. Se encontraron diferencias significativas en la gestión del riesgo biológico laboral en función del sistema preventivo elegido por la empresa concluyendo que la protección a la exposición laboral a agentes biológicos no está desarrollada por completo porque no se dispone de herramientas que permitan su fácil realización y por lo tanto la gestión de los riesgos biológicos general no es adecuada (AU)

The aim of this study was to obtain information on the level of exposure and protection of workers to biological agents at work in relation to the preventive system choosen for the companies. An study in which 590 workers from 59 Spanish companies in which 2 questionnaires were given, one for the company and other for the workers, yielding a final sample of 518 workers from 51 companies in which there is exposure to biological agents. Our results provide significant differences in the management of occupational exposure to biological agents depending on the preventive system chosen by the company concluding that the protection is not fully developed because there are not enough tools available that allow easy implementation and the overall management of biological risks is inadequate (AU)

Pybox monolithic miniflow reactors for continuous asymmetric cyclopropanation reaction under conventional and supercritical conditions.

Supported catalysts having pybox chiral moieties were prepared as macroporous monolithic miniflow systems. These catalysts are based on styrene-divinylbenzene polymeric backbones having different compositions and pybox chiral moieties. Their corresponding ruthenium complexes were tested for the continuous flow cyclopropanation reaction between styrene and ethyldiazoacetate (EDA) under conventional conditions and in supercritical carbon dioxide (scCO2). Ru-Pybox monolithic miniflow reactors not only provided a highly efficient and robust heterogeneous chiral catalyst but also allowed us to develop more environmental reaction conditions without sacrificing the global efficiency of the process.

Are AM1 ligand-protein binding enthalpies good enough for use in the rational design of new drugs?

We have examined the performance of semiempirical quantum mechanical methods in solving the problem of accurately predicting protein-ligand binding energies and geometries. Firstly, AM1 and PM3 geometries and binding enthalpies between small molecules that simulate typical ligand-protein interactions were compared with high level quantum mechanical techniques that include electronic correlation (e.g., MP2 or B3LYP). Species studied include alkanes, aromatic systems, molecules including groups with hypervalent sulfur or with donor or acceptor hydrogen bonding capability, as well as ammonium or carboxylate ions. B3LYP/6-311+G(2d,p) binding energies correlated very well with the BSSE corrected MP2/6-31G(d) values. AM1 binding enthalpies also showed good correlation with MP2 values, and their systematic deviation is acceptable when enthalpies are used for the comparison of interaction energies between ligands and a target. PM3 otherwise gave erratic energy differences in comparison to the B3LYP or MP2 approaches. As one would expect, the geometries of the binding complexes showed the known limitations of the semiempirical and DFT methods. AM1 calculations were subsequently applied to a test set consisting of "real" protein active site-ligand complexes. Preliminary results indicate that AM1 could be a valuable tool for the design of new drugs using proteins as templates. This approach also has a reasonable computational cost. The ligand-protein X-ray structures were reasonably reproduced by AM1 calculations and the corresponding AM1 binding enthalpies are in agreement with the results from the "small molecules" test set.

Benzo[b]thiophenesulphonamide 1,1-dioxide derivatives inhibit tNOX activity in a redox state-dependent manner.

Benzo[b]thiophenesulphonamide 1,1-dioxide (BTS) derivatives are strong cytotoxic agents that induce reactive oxygen species (ROS) overproduction and apoptosis in tumour cells. Although the precise origin of BTS-induced ROS is not known, a clear correlation between their cytotoxic effect and ability to inhibit a tumour-associated NADH oxidase (tNOX) activity of the plasma membrane has been described. To analyse the putative implication of tNOX in BTS-induced ROS generation, in this work we have synthesised and tested a new BTS derivative, the 6-[N-(2-phenylethyl)]benzo[b]thiophenesulphonamide 1,1-dioxide. According to its high lipophilicity, this compound showed a strong cytotoxic activity against a panel of six human tumour cell lines, including two human leukaemia (K-562 and CCRF-CEM) and four human solid tumours (HT-29, HTB54, HeLa and MEL-AC). We also tested the ability of this compound to inhibit the tNOX activity and we found an absolute dependence of this inhibition on the redox state of the tNOX: while under reducing conditions, that is, 100 mM GSH, the drug inhibits strongly the NOX activity with an EC(50) of about 0.1 nM, under oxidising conditions, there is no effect of the drug or just a slight stimulation of activity.

Synthesis and cytotoxic activity of lipophilic sulphonamide derivatives of the benzo[b]thiophene 1,1-dioxide.

In the search of new compounds with antineoplastic activity, we have analysed the effect of several structural modifications on the nucleus 6-benzo[b]thiophenesulphonamide 1,1-dioxide on its cytotoxic activity on tumour cells. Lipophilic substituents on the sulphonamide group significantly increased the cytotoxic activity measured using a panel of human tumour cell lines. Only slight variations on cytotoxicity were obtained when the sulphonamide group occupied the position 5 of the system. The most active compound was the N-4-methoxyphenyl derivative 15, which showed GI(50) values of 1-9 nM against HT-29, CCRF-CEM, K-562 and MEL-AC cells and of 200 nM against HTB-54 cells. Free access to the 3-position of the heterocyclic system seems to be required to obtain cytotoxic derivatives. Derivative 15 was also active at the same level of commercial Doxorubicine against cultured normal human lung fibroblasts.

New benzo(b)thiophenesulphonamide 1,1-dioxide derivatives induce a reactive oxygen species-mediated process of apoptosis in tumour cells.

In this work, we describe the process of cell death induced by a series of new benzo(b)thiophenesulphonamide 1,1-dioxide derivatives (BTS) that have been selected as candidate antineoplastic drugs. Human leukaemic CCRF-CEM cells incubated with BTS undergo a typical apoptotic process that includes cell shrinkage, phosphatidylserine translocation to the cell surface, mitochondrial dysfunction, caspase activation, chromatin condensation and internucleosomal DNA degradation. Mitochondrial alterations included dissipation of the mitochondrial membrane potential, oxidation of the phospholipid cardiolipin, release of cytochrome c and uncoupling of the mitochondrial respiratory chain, leading to a decrease of the intracellular ATP pool. Activation of caspase-8, -9 and -3 takes place during BTS-induced apoptosis. Either the addition of the specific caspase-8 inhibitor Z-IETD-fmk, or the overexpression of the antiapoptotic protein Bcl-2 significantly prevented BTS-induced apoptosis, suggesting the involvement of both caspase-8-regulated and mitochondria-dependent signalling pathways in this process. BTS induce a significant increase in the production and accumulation of intracellular reactive oxygen species (ROS) that can be observed within minutes after drug addition. Moreover, cytochrome c release, caspase-3 activation and cell death can be completely abrogated by a previous incubation with the antioxidant N-acetyl-cysteine. These results suggest that ROS are essential mediators in BTS-induced apoptosis.

New cytotoxic benzo(b)thiophenilsulfonamide 1,1-dioxide derivatives inhibit a NADH oxidase located in plasma membranes of tumour cells.

A series of benzo(b)thiophenesulfonamide 1,1-dioxide derivatives (BTS) have been designed and synthesized as candidate antineoplastic drugs. Several of these compounds have shown in vitro cytotoxic activity on leukaemic CCRF-CEM cells. The cytotoxic BTS, but not the inactive ones, were able to inhibit a tumour cell-specific NADH oxidase activity present in the membrane of CCRF-CEM cells.

Theoretical (DFT) insights into the mechanism of copper-catalyzed cyclopropanation reactions. Implications for enantioselective catalysis.

The mechanism of the copper(I)-catalyzed cyclopropanation reaction has been extensively investigated for a medium-size reaction model by means of B3LYP/6-31G(d) calculations. The starting ethylene complex of the N,N'-dimethylmalonaldiimine--copper (I) catalyst undergoes a ligand exchange with methyl diazoacetate to yield a reaction intermediate, which subsequently undergoes nitrogen extrusion to generate a copper--carbene complex. The cyclopropanation step takes place through a direct carbene insertion of the metal--carbene species to yield a catalyst--product complex, which can finally regenerate the starting complex. The stereochemical predictions of a more realistic model (by considering a chiral bis(oxazoline)--copper (I) catalyst) have been rationalized in terms of steric repulsions, showing good agreement with experimental data.

CoMFA-SIMCA model for antichagasic nitrofurazone derivatives.

The physico-chemical properties of some 5-nitro-2-furaldehyde semicarbazones (nitrofurazones) and thiophene analogues were compared with their in vitro and in vivo trypanocidal activity against Trypanosoma cruzi (Tulahuen strain). 3D-QSAR models were obtained by applying the SIMCA methodology to the electrostatic and steric fields (CoMFA fields) of the molecules. Nitrofurazones bearing N4 substituents. which cover a range of 14-17 A from the nitro group with a thickness of about 6 A when considering the extended conformer. produced complete survival in infected mice. The in vitro model allows larger N4 substituents than the SURVival model, but they must not bear positive centres in the region 15-16 A from the nitro group. Moreover, the in vitro model is in agreement with the active site of trypanothione reductase (TR). Both models can be of use in the design of novel drugs bearing an amide-like group at a distance of 7-9 A from an easily reducible group.

Synthesis and cytotoxic activity of N-(2-pyridylsulfenyl)urea derivatives. A new class of potential antineoplastic agents.

Starting from a 3D-model for the antineoplastic activity of diarylsulfonylureas several new features were proposed and tested. Both types of assayed compounds, the N-(2-pyridylsulfonyl)urea and N-(2-pyridylsulfenyl)urea derivatives, inhibited by 50% the growth of the CCRF-CEM cell line at a dosage near to 1 microM. The N -(2-pyrimidinyl) derivative of the sulfenylurea 6c showed a better profile against HT-29, K-562 and HTB-54 tumor cell lines than the corresponding sulfonylurea 6b. Structural modifications on aryl systems affected differently to the cytotoxic activity shown by the compounds against each cell line.

New 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e]pyrimidin-5-one derivatives as diuretics.

A series of new 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e] pyrimidin-5-ones 3-substituted and/or 8,9-hydrogenated was prepared and tested for their diuretic, natriuretic and kaliuretic activities on male Wistar rats at a dosage of 25 mg/kg or less. Diuretic and saliuretic activities were strongly influenced by substituents in 3-position. Quantitative structure-activity relationships show that electron withdrawn substituents in 3-position enhance both diuretic and saliuretic activities at 25 mg/kg. Global analysis of the variations introduced on pyridine, pyrimidine and thiazole rings of this tricyclic system showed an increases of diuretic and natriuretic activities when the formal charge on N9a and C9b increases. Potassium ion excretion also increases, although not as drastically a in the earlier cases. Regression equations were calculated by partial least squares method (PLS) and validated by the cross-validation (leave-one-out) technique.

New 2-aryl-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidin-4-one derivatives as diuretics.

2-Aryl-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidin-4-one derivatives having various substituents at the 4'-position, H or methyl at 1,3-positions and nitro or amino at 6-position were prepared and tested for their diuretic, natriuretic and kaliuretic activities on male Wistar rats at a dosage of 25 mg/kg or less. 2-(3-Pyridyl) derivatives were inactive. 1,3-Dimethyl-6-nitro-2-phenyl derivatives (1) were active depending on the electronic character of the 4'-substituent but at the same time were sodium-sparing. However, 1(H),3(H)-6-nitro-2-phenyl derivatives (2) were generally inactive as diuretics but active as potassium-sparing drugs. 6-Amino-1(H),3(H)-2-phenyl derivatives (4) were active as diuretics depending on dipolar moment of the substituent at the 4'-position, and induced moderate potassium release. The 6-amino-2-(4-trifluoromethylphenyl)-1, 2,3,4-tetrahydropyrido [2,3-d]pyrimidin-4-one (4f) remained active up to a dosage of 3 mg/kg. The structure-activity relationships were carried out in light of the adaptative least squares (ALS) method and discriminant functions for diuretic compounds were established.

Quantitative structure-mutagenic activity relationships of triazino indole derivatives.

The mutagenicity of 3-(4'-benzylidenamino)-5H-1,2,3-triazin[5,4-b]-indol-4-one derivatives, new compounds with considerable platelet antiaggregating activity, was assayed with the Ames test using the Salmonella typhimurium strains TA97, TA98, TA100 and TA102. The adaptive least-squares method (ALS method) was used to carry out a quantitative structure-activity relationship (QSAR) analysis. Three equations, based on 10 congeners, were found for strains TA97, TA98 and TA100. The results suggest that lipophilicity of the substituent decreases the mutagenicity of the series.

New 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e]pyrimidine derivatives as diuretics.

New 5H-[1,3]thiazolo[3,2-a]pyrido[3,2-e]pyrimidines 1 and 6,10-dihydro-5H-pyrido[3',2':5,6]pyrimido[2,1-c] [1,2,4]triazines 4 with 5-one, 5-thione or 5-hydrazono substituents and in some cases 1,2,3,4 or 8,9 hydrogenated are synthetized. The diuretic, natriuretic and kaliuretic activities of these compounds in Wistar rats at a dose of 24 mg/kg were estimated. A series of 24 possible derivatives of 1 and 4 possessing diuretic and saliuretic activities are investigated for structure-activity relationships in light of Fujita-Ban model. The Fujita-Ban group contributions have been calculated for different structural variations on the parent ring 1a. It is observed that the hydrogenation of pyridine, [1,3]thiazole or [1,2,4]triazine rings on 1 or 4 decrease the diuretic and saliuretic activities.

Diuretic and hypotensive activities of 4-anilino derivatives of 2-methylthiopyrido[2,3-d]pyrimidines.

The synthesis of a series of 12 compounds referring to 4-anilino-2-methylthiopyrido [2,3-d]pyrimidines (1-12), and the results of a study of their diuretic, saliuretic and antihypertensive activities are reported. Most of this compounds showed significant diuretic activity at the dosage of 3-24 mg/kg. The 4-Anilino-2-methylthiopirido[2,3-d]pyrimidine 1 remained active to a dosage of 1 mg/kg. The diuretic activity of these compounds implied an increase in the Na+ excretion. Some of the most active diuretics have been studied for antihypertensive effect.