Exploring the nature of the H-bonds between the human class II MHC protein, HLA-DR1 (DRB*0101) and the influenza virus hemagglutinin peptide, HA306-318, using the quantum theory of atoms in molecules.

The nature of the H-bonds between the human protein HLA-DR1 (DRB*0101) and the hemagglutinin peptide HA306-318 has been studied using the Quantum Theory of Atoms in Molecules for the first time. We have found four H-bond groups: one conventional CO··HN bond group and three nonconventional CO··HC, π··HC involving aromatic rings and HN··HCaliphatic groups. The calculated electron density at the determined H-bond critical points suggests the follow protein pocket binding trend: P1 (2,311) >> P9 (1.109) > P4 (0.950) > P6 (0.553) > P7 (0.213) which agrees and reveal the nature of experimental findings, showing that P1 produces by a long way the strongest binding of the HLA-DR1 human protein molecule with the peptide backbone as consequence of the vast number of H-bonds in the P1 area and at the same time the largest specific binding of the peptide Tyr308 residue with aromatic residues located at the binding groove floor. The present results suggest the topological analysis of the electronic density as a valuable tool that allows a non-arbitrary partition of the pockets binding energy via the calculated electron density at the determined critical points.

Optical fiber spectroelectrochemical device for detection of catechol at press-transferred single-walled carbon nanotubes electrodes.

A new long-optical-pathway spectroelectrochemical cell for absorptometric measurements in the UV-Vis region was developed. This cell consists of two optical fibers brought face to face and fixed on the working electrode support. As a proof of concept, the spectroelectrochemical cell was applied to the determination of catechol using a press-transferred single-walled carbon nanotube film as the working electrode. Voltabsorptometry was demonstrated to be very helpful in understanding the mechanism of catechol oxidation. The experiments showed that the main oxidation product is o-benzoquinone, but other soluble side products are also observed. Multivariate calibration explains the selection of 390 nm as the best wavelength for the univariate absorptometric determination of catechol, avoiding the interference of oxidation side products. Catechol was quantified using both the electrochemical and the spectroscopic signal, demonstrating that this hybrid technique is an autovalidated analytical method. Dual detection of catechol was also carried out using amperometric spectroelectrochemistry. Finally, spectroelectrochemistry was used to quantify catechol in the presence of hydroquinone.

Spatial scanning spectroelectrochemistry. Study of the electrodeposition of Pd nanoparticles at the liquid/liquid interface.

Spatial scanning spectroelectrochemistry is a new analytical technique that provides spectral information at different distances from an electrified liquid/liquid interface where an electrochemical process takes place. As a proof of concept, we have studied two different electrochemical processes at the electrified liquid/liquid interface: (1) Ru(bpy)(3)(2+) transfer through the water/1,2-dichloroethane interface and (2) electrodeposition of Pd nanoparticles at the water/1,2-dichloroethane interface. The instrumental setup developed consists of a movable slit for the light beam to sample at well-defined positions on both sides of the interface, providing important information about the chemical process occurring. If the slit is scanned at different distances from the interface during an electrochemical experiment, a complete picture of the reactions and equilibria in the diffusion layer can be obtained. For example, in the case of the Ru(bpy)(3)(2+), the experiments show clearly how the complex is transferred from one phase to the other. In the case of electrosynthesis of Pd nanoparticles, it is demonstrated that nanoparticles are not only deposited at the interface but diffuse to the aqueous bulk solution. These in situ observations were confirmed by ex situ experiments using transmission electron microscopy.

Effects of oxidants and antioxidants on proliferation of endometrial stromal cells.

OBJECTIVE: To evaluate the effects of oxidative stress and antioxidants on proliferation of endometrial stromal cells. DESIGN: In vitro study. SETTING: Academic laboratory. PATIENT(S): Women, with and without endometriosis, of reproductive age. INTERVENTION(S): Culture of endometrial stromal cells with antioxidants or with agents inducing oxidative stress. MAIN OUTCOME MEASURE(S): Proliferation of endometrial stromal cells as determined by thymidine incorporation assay and 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) assay. RESULT(S): Antioxidants induced a dose-dependent inhibition of thymidine incorporation: vitamin E succinate was inhibitory at 10-100 microM (by 43%-95%), ebselen at 10-30 microM (by 29%-77%), and N-acetylcysteine at 10-30 mM (by 52%-85%). In contrast, modest oxidative stress induced by hypoxanthine/xanthine oxidase (1 mM/3-30 microU/mL) stimulated proliferation by 40%-62%. H2O2 (1 microM) increased DNA synthesis by 56%. Comparable findings were obtained using MTT proliferation assay. Antioxidants inhibited proliferation: vitamin E succinate (100 microM) by 91%, ebselen (30 microM) by 81%, and N-acetylcysteine (30 mM) by 95%. Hypoxanthine/xanthine oxidase (1 mM/30 microU/mL) and H2O2 (1 microM) stimulated growth by 122% and 58%, respectively. CONCLUSION(S): Reactive oxygen species may modulate growth of endometrial stroma. Under pathologic conditions such as endometriosis, increased oxidative stress and depletion of antioxidants may contribute to excessive growth of endometrial stromal cells.

Mevastatin inhibits ovarian theca-interstitial cell proliferation and steroidogenesis.

OBJECTIVE: Statins reduce cardiovascular risks by improving hypercholesterolemia, reducing vascular smooth muscle proliferation, and ameliorating inflammation. Polycystic ovary syndrome (PCOS) is associated with increased cardiovascular risks and is characterized by ovarian theca-interstitial hyperplasia and hyperandrogenism. This study tested the hypothesis that mevastatin limits theca-interstitial proliferation and decreases steroidogenesis. DESIGN: In vitro study. SETTING: Academic laboratory. PATIENT(S): None. INTERVENTION(S): Effects of mevastatin on cultured theca-interstitial cells. MAIN OUTCOME MEASURE(S): Proliferation was evaluated by determination of DNA synthesis using thymidine incorporation assay and by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) assay. Production of P and T was determined by specific radioimmunoassays. RESULT(S): Mevastatin induced a profound concentration-dependent inhibition of DNA synthesis. At the highest concentration (30 microM), mevastatin inhibited DNA synthesis by 92%. Similarly, in the MTT proliferation assay, mevastatin induced a concentration-dependent decrease in cell number. Mevastatin decreased production of P (by up to 49%) and T (by up to 52%); these effects remained significant when the effect on cell culture protein content was accounted for. CONCLUSION(S): Mevastatin inhibits proliferation of theca-interstitial cells; it also inhibits P and T production independently of the effects on cell growth. These findings provide a foundation for studies evaluating statins as potential therapeutic agents in the treatment of ovarian mesenchymal hyperplasia and hyperandrogenism characteristic of PCOS.

Incidencia de fracturas maxilofaciales en el municipio Artemisa / Incidence of jaw fractures in the municipality of Artemisa / Incidence des fractures maxillo-faciales à Artemisa

Se realiza un estudio sobre la incidencia de las fracturas maxilofaciales tratadas en el Servicio de Cirugía Maxilofacial de Artemisa, entre los años 1994-97. Del total de 167 casos tratados el 62,3 % correspondió al sexo masculino y el 37,7 % al femenino. Las causas más frecuentes fueron los accidentes del tránsito, las caídas, las riñas y los accidentes deportivos y del trabajo. Al igual que en la mayoría de los estudios la fractura nasal fue la más frecuente, siguiéndole en orden las maxilomolares, las dentoalveolares y las mandibulares.

A study on the incidence of jaw fractures treated at the Service of Maxillofacial Surgery, in Artemisa, from 1994 to 1997, was conducted. Of the 167 cases that received treatment 62.3 % were males and 37.7 % females. The most frequent causes were traffic accidents, falls, quarrels, and sports and working accidents. As in most of the studies, nasal fracture was the most frequent, followed by maxillomolar, dento-alveolar and jaw fractures.

Une étude su l´incidence des fractures maxillo-faciales traitées au Service de Chirurgie maxillo-faciale d´Artemisa a été réalisée entre 1994 et 1997. Du total de 167 cas traités, 62,3 % correspond au sexe masculin et 37,7 % au sexe féminin. Les causes les plus fréquentes ont été les accidents du trafit, les chutes, les bagarres et les accidents de sport et de travail. La fracture du nez a été la plus fréquente, de même que la plupart des études, puis les fractures maxillo-molaires, les dento-alvéolaires et les mandibilaires.