Shock-Free Ferroelectric Liquid Crystal Compositions: Optimized Chiral Compounds and Their Mixing Ratio with Non-Chiral Components

The best chiral compounds for the design of shock-free ferroelectric liquid crystal compositions with a wide temperature range of the chiral smectic C phase have been developed. For these experiments about 70 different 4-ring chiral compounds were synthesized and investigated. The influence of the chiral fragment, the mixing ratio between chiral and non-chiral molecules, and the pretilt angle of the alignment materials on the quality and on the mechanical stability of the orientation were investigated. New optimized ferroelectric liquid crystal compositions for the fabrication of shock-free ferroelectric liquid crystal displays with high contrast ratio are presented

Elaboration et évaluation d'algorithmes de dépistage des MST chez la femme enceinte à Libreville, Gabon

La lutte contre les MST constitue une priorité de santé publique des pays en développement de par leurs complications propres, en particulier chez la femme, et de par leur rôle facilitant la transmission du VIH. Une des stratégies de lutte contre les MST est le diagnostic et le traitement précoces de ces infections. Les MST, en particulier les infections à gonocoques et à #Chlamydiae trachomatis$sont d'un diagnostic difficile chez la femme en l'absence d'examens complémentaires, ceux-ci faisant souvent défaut au niveau des structures de soins de santé primaire. Dans ce contexte, l'approche syndromique, basée sur la prise en compte de signes et symptômes, peut permettre de standardiser et d'améliorer la prise en charge des patientes. Une étude de prévalence et de facteurs de risque des MST, effectuées chez 192 femmes enceintes consultant en PMI à Libreville (Gabon), en septembre 1993, a confirmé la prévalence des MST dans cette population (13,5$). L'évaluation de différentes stratégies diagnostiques et d'algorithmes montre que, quel que soit le niveau d'examen (données d'interrogatoire, examen clinique simple, examen au spéculum), l'utilisation de scores intégrant des facteurs de risque, des symptômes et des signes cliniques est plus performante que les algorithmes hiérarchiques. Ces scores présentent des sensibilités et des spécificités élevées et sont d'une mise en oeuvre facile. Leur application pourrait donc permettre le dépistage efficace des MST et éviter, ainsi, une grande partie des complications maternelles et infantiles. (Résumé d'auteur

Light microscopic immunocytochemical identification of leucine enkephalin

Leucine-enkephalin is a potent and naturally-occurring opioid peptide which serves to inhibit other neurotransmitters involved with pain perception, thereby reducing its emotional and physical impact. Nevertheless, there is little data in the literature concerning leucine-enkephalin-immunoreactivity (Leu-enk-ir) in the human claustrum. The objectives of this study were to confirm the existence of leucine-enkephalin immunoreactive neurons and fibers in the human claustrum. Light microscopy was used to describe their morphology and distribution. Samples of claustrum were obtained from the brains of two females (39 and 48 years of age) and two males (27 and 42 years of age). The brains did not show any overt signs of pathology or trauma. Immunoreactivity to Leuenk was assessed via the Avidin-Biotin Complex Method. Light-microscopic analysis confirmed the presence of Leu-enk-ir neurons and fibres in all areas of the human claustrum. The cell bodies varied in shape and size, and were divided into three groups: small, medium and large. The density of immunostaining varied both within and between the cell types, with some neurons, staining more darkly or lightly than others. The large and medium sized cells most likely correspond to claustrocortical projection neurons while the small-sized cells appear to be inhibitory interneurons. It is our hope that these results will be contributed to a better understanding the functions of claustrum, in both health and disease, given its relationship with the development of autism, schizophrenia, Alzheimer disease, Parkinson disease and Huntington disease

A Novel Docetaxel-Loaded Poly (ε-Caprolactone)/Pluronic F68 Nanoparticle Overcoming Multidrug Resistance for Breast Cancer Treatment

Multidrug resistance (MDR) in tumor cells is a significant obstacle to the success of chemotherapy in many cancers. The purpose of this research is to test the possibility of docetaxel-loaded poly (ε-caprolactone)/Pluronic F68 (PCL/Pluronic F68) nanoparticles to overcome MDR in docetaxel-resistance human breast cancer cell line. Docetaxel-loaded nanoparticles were prepared by modified solvent displacement method using commercial PCL and self-synthesized PCL/Pluronic F68, respectively. PCL/Pluronic F68 nanoparticles were found to be of spherical shape with a rough and porous surface. The nanoparticles had an average size of around 200 nm with a narrow size distribution. The in vitro drug release profile of both nanoparticle formulations showed a biphasic release pattern. There was an increased level of uptake of PCL/Pluronic F68 nanoparticles in docetaxel-resistance human breast cancer cell line, MCF-7 TAX30, when compared with PCL nanoparticles. The cytotoxicity of PCL nanoparticles was higher than commercial Taxotere®in the MCF-7 TAX30 cell culture, but the differences were not significant (p > 0.05). However, the PCL/Pluronic F68 nanoparticles achieved significantly higher level of cytotoxicity than both of PCL nanoparticles and Taxotere®(p < 0.05), indicating docetaxel-loaded PCL/Pluronic F68 nanoparticles could overcome multidrug resistance in human breast cancer cells and therefore have considerable potential for treatment of breast cancer

Mutational Specificity of γ-Radiation-Induced Guanine−Thymine and Thymine−Guanine Intrastrand Cross-Links in Mammalian Cells and Translesion Synthesis Past the Guanine−Thymine Lesion by Human DNA Polymerase η†

ABSTRACT: Comparative mutagenesis of γ- or X-ray-induced tandem DNA lesions G[8,5-Me]T and T[5-Me,8]G intrastrand cross-links was investigated in simian (COS-7) and human embryonic (293T) kidney cells. For G[8,5-Me]T in 293T cells, 5.8 % of progeny contained targeted base substitutions, whereas 10.0 % showed semitargeted single-base substitutions. Of the targeted mutations, the G f T mutation occurred with the highest frequency. The semitargeted mutations were detected up to two bases 5 ′ and three bases 3 ′ to the cross-link. The most prevalent semitargeted mutation was a C f T transition immediately 5 ′ to the G[8,5-Me]T cross-link. Frameshifts (4.6%) (mostly small deletions) and multiple-base substitutions (2.7%) also were detected. For the T[5-Me,8]G cross-link, a similar pattern of mutations was noted, but the mutational frequency was significantly higher than that of G[8,5-Me]T. Both targeted and semitargeted mutations occurred with a frequency of ∼16%, and both included a dominant G f T transversion. As in 293T cells, more than twice as many targeted mutations in COS cells occurred in T[5-Me,8]G (11.4%) as in G[8,5-Me]T (4.7%). Also, the level of semitargeted single-base substitutions 5 ′ to the lesion was increased and 3 ′ to the lesion decreased in T[5-Me,8]G relative to G[8,5-Me]T in COS cells. It appeared that the majority of the base substitutions at or near the cross-links resulted from incorporation of dAMP opposite the template base, in agreement with the so-called “A-rule”. To determin