How the first biopolymers could have evolved.

In this work, we discuss a possible origin of the first biopolymers with stable unique structures. We suggest that at the prebiotic stage of evolution, long organic polymers had to be compact to avoid hydrolysis and had to be soluble and thus must not be exceedingly hydrophobic. We present an algorithm that generates such sequences for model proteins. The evolved sequences turn out to have a stable unique structure, into which they quickly fold. This result illustrates the idea that the unique three-dimensional native structures of first biopolymers could have evolved as a side effect of nonspecific physicochemical factors acting at the prebiotic stage of evolution.

Selective pressure of a quinoxaline nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) on HIV-1 replication results in the emergence of nucleoside RT-inhibitor-specific (RT Leu-74-->Val or Ile and Val-75-->Leu or Ile) HIV-1 mutants.

The quinoxaline nonnucleoside RT inhibitor (NNRTI) (S)-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4- dihydroquinoxaline-2(1H)-thione (HBY 097) was used to select for drug-resistant HIV-1 variants in vitro. The viruses first developed mutations affecting the NNRTI-binding pocket, and five of six strains displayed the RT G190-->E substitution, which is characteristic for HIV-1 resistance against quinoxalines. In one variant, a new mutant (G190-->Q) most likely evolved from preexisting G190-->E mutants. The negative charge introduced by the G190-->E substitution was maintained at that site of the pocket by simultaneous selection for V179-->D together with G190-->Q. After continued exposure to the drug, mutations at positions so far known to be specific for resistance against nucleoside RT inhibitors (NRTIs) (L74-->V/I and V75-->L/I) were consistently detected in all cultures. The inhibitory activities of the cellular conversion product of 2',3'-dideoxyinosine (ddI, didanosine), 2',3'-dideoxyadenosine (ddA) and of 2',3'-didehydro-3'-deoxythymidine (d4T, stavudine) against these late-passage viruses were shown to be enhanced with the L74-->V/I RT mutant virus as compared with the wild-type (wt) HIV-1MN isolate. Clonal analysis proved linkage of the codon 74 and codon 75 mutations to the NNRTI-specific mutations in all RT gene fragments. The nonnucleoside- and nucleoside-resistance mutation sites are separated by approximately 35 A. We propose that the two sites "communicate" through the template-primer which is situated in the DNA-binding cleft between these two sites. Quinoxalines cause high selective pressure on HIV-1 replication in vitro; however, the implication of these findings for the treatment of HIV-1 infection has yet to be determined.

Evaluation of pronoun resolution algorithm for Spanish dialogues

In this paper, we present an algorithm for anaphora resolution in Spanish dialogues and an evaluation of the algorithm for pronominal anaphora. The proposed algorithm uses both linguistic information and the structure of the dialogue to find the antecedent of the anaphors. The system has been evaluated on ten dialogues.

Circumstellar emission in Be/X-ray binaries of the Magellanic Clouds and the Milky Way

Aims. We study the optical and near-infrared colour excesses produced by circumstellar emission in a sample of Be/X-ray binaries. Our main goals are exploring whether previously published relations, valid for isolated Be stars, are applicable to Be/X-ray binaries and computing the distance to these systems after correcting for the effects of the circumstellar contamination. Methods. Simultaneous UBVRI photometry and spectra in the 3500−7000 Å spectral range were obtained for 11 optical counterparts to Be/X-ray binaries in the LMC, 5 in the SMC and 12 in the Milky Way. As a measure of the amount of circumstellar emission we used the Hα equivalent width corrected for photospheric absorption. Results. We find a linear relationship between the strength of the Hα emission line and the component of E(B − V) originating from the circumstellar disk. This relationship is valid for stars with emission lines weaker than EW ≈ −15   Å. Beyond this point, the circumstellar contribution to E(B − V) saturates at a value ≈0.17   mag. A similar relationship is found for the (V − I) near infrared colour excess, albeit with a steeper slope and saturation level. The circumstellar excess in (B − V) is found to be about five times higher for Be/X-ray binaries than for isolated Be stars with the same equivalent width EW(Hα), implying significant differences in the physical properties of their circumstellar envelopes. The distance to Be/X-ray binaries (with non-shell Be star companions) can only be correctly estimated by taking into account the excess emission in the V band produced by free-free and free-bound transitions in the circumstellar envelope. We provide a simple method to determine the distances that includes this effect.

Reacciones adversas a los alimentos

Introducción: Las respuestas anómalas tras la ingestión de alimentos es un hecho ampliamente conocido y frecuente. Se pueden producir diferente tipo de reacciones, entre las cuales destacan la alergia alimentaria y la intolerancia alimentaria. Objetivos: Elaborar un protocolo de actuación que permita realizar un proceso estandarizado a la hora de desarrollar un diagnostico precoz y plantear un plan de cuidado apropiado y específico para cada usuario. Material y métodos: Para operacionalizar la búsqueda en las bases de datos fue utilizado los descriptores enfermería, AP, intolerancia, alergia, infancia, celiaquía con este fin fueron consultadas las siguientes bases indexadoras PubMed, cuiden y Google académico. Resultados: En España, en un periodo de 15 años (desde 1997 a 2012) han pasado de existir 800.000 a 3 millones de personas que padecen reacciones adversas a los alimentos. Con respecto a las alergias alimentarias podemos decir que es la segunda más frecuente. Afecta a uno de cada 50 niños. La prevalencia real en adultos es del 2%, sin embargo la incidencia en la población infantil es del 3-7%. Conclusiones: Es importante la acción de enfermería en la detección de casos intolerancias o alergias. Es importante el papel de la enfermería en el seguimiento de múltiples enfermedades crónicas o no, debido al contacto que tenemos con el usuario. Es necesario fomentar la comunicación entre los profesionales del equipo de atención primaria, para mejorar la calidad asistencial y facilitar el diagnóstico, tratamiento y seguimiento de las diversas enfermedades.

Modus concionandi, et explanatio in Psalm. cxxxvj. Super flumina Babylonis / Didaco Stella Minorita auctore.

Colofón

Sermones de sanctis / diui Vincentii ; de sanctis & in orationem dominicam sermonum opus sancti Vincentij, ordinis Praedicatorum, diuini praeconis, ad vetustorum exemplarium fidem diligenter emendatum ; cum eorum indice locupletissimo.

Capitulares grab. xil.