RESUMEN
A dose-escalation study of docetaxel (DOC), cisplatin (CDDP), and 5-fluorouracil (5-FU; DCF combination regimen) was performed to determine the maximum-tolerated dose (MTD), recommended dose (RD) and dose-limiting toxicities (DLT) in advanced esophageal carcinoma. Eighteen patients with esophageal carcinoma were enrolled and received DCF combination therapy at different dose levels. DLTs included febrile neutropenia and oral mucositis. DLT occurred in 2 out of 6 patients at level 2 and 3. The study proceeded to level 4, according to the protocol. The level 4 dose was defined as the MTD and the level 3 dose was defined as the RD. The RD for DCF combination chemotherapy for advanced esophageal carcinoma in the present study was 70 mg/m(2) DOC plus 70 mg/m(2) CDDP on day 1 plus 700 mg/m(2) 5-FU on days 1-5 at 4-week intervals. This regimen was tolerable and highly active. A phase II study has been started.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Cisplatino/administración & dosificación , Neoplasias Esofágicas/tratamiento farmacológico , Fluorouracilo/administración & dosificación , Taxoides/administración & dosificación , Anciano , Docetaxel , Relación Dosis-Respuesta a Droga , Neoplasias Esofágicas/patología , Femenino , Humanos , Masculino , Dosis Máxima Tolerada , Persona de Mediana Edad , Estudios ProspectivosRESUMEN
Among various Z-form DNA inducers, such as transition metal complexes, polyamines and high ionic concentrations, 8-methylguanine have received attention as efficient chemical modifications. Although it is clear that m8-modified guanine base markedly stabilizes the Z conformation of short oligonucleotides under physiological salt conditions, how sequence composition affects the preference of Z-DNA is still not well established. In this study, various oligomers of d(CG)n or d(GC)n containing either 8-methylguanine in a different position were synthesized and their capacity of stabilizing Z-DNA were evaluated by CD spectra and then compared with each other. It is was found out that the Z-DNA stabilizing effect depend on the order of arrangement of m(8)G and m(8)rG in DNA strands and the center position is the most effective to stabilize the Z-DNA and promote the B to Z transition.
Asunto(s)
ADN Forma B/química , ADN de Forma Z/química , Guanina/análogos & derivados , Oligodesoxirribonucleótidos/química , Secuencia de Bases , Dicroismo Circular , Guanina/químicaRESUMEN
The well-demonstrated biological functions of DNA G-quadruplex inside cells call for small molecules that can modulate these activities by interacting with G-quadruplexes. However, the paucity of the understanding of the G-quadruplex stability contributed from submolecular elements, such as loops and tetraguanine (G) planes (or G-quartets), has hindered the development of small-molecule binders. Assisted by click chemistry, herein, we attached pulling handles via two modified guanines in each of the three G-quartets in human telomeric G-quadruplex. Mechanical unfolding using these handles revealed that the loop interaction contributed more to the G-quadruplex stability than the stacking of G-quartets. This result was further confirmed by the binding of stacking ligands, such as telomestatin derivatives, which led to similar mechanical stability for all three G-quartets by significant reduction of loop interactions for the top and bottom G-quartets. The direct comparison of loop interaction and G-quartet stacking in G-quadruplex provides unprecedented insights for the design of more efficient G-quadruplex-interacting molecules. Compared to traditional experiments, in which mutations are employed to elucidate the roles of specific residues in a biological molecule, our submolecular dissection offers a complementary approach to evaluate individual domains inside a molecule with fewer disturbances to the native structure.
Asunto(s)
G-Cuádruplex , Dicroismo Circular , Resonancia por Plasmón de SuperficieRESUMEN
A 2-aminothieno[3,4-d]pyrimidine G-mimic deoxyribonucleoside, (th)dG, was synthesized and incorporated readily into oligonucleotides as a versatile fluorescent guanine analogue. We demonstrate that (th)dG enables the visual detection of Z-DNA successfully based on different π-stacking of B- and Z-DNA.
Asunto(s)
ADN Forma B/análisis , ADN de Forma Z/análisis , Desoxiguanosina/análogos & derivados , Colorantes Fluorescentes/química , Oligonucleótidos/química , Secuencia de BasesRESUMEN
A palladium-catalyzed asymmetric synthesis of 2-pyrrolidinones with a quaternary stereocenter at the 3-position has been achieved by the reaction of γ-methylidene-δ-valerolactones with alkyl isocyanates. High enantioselectivity has been realized by employing a newly synthesized chiral phosphoramidite ligand.
Asunto(s)
Carbono/química , Paladio/química , Pirrolidinonas/química , Catálisis , Cristalografía por Rayos X , Isocianatos/química , Lactonas/química , Ligandos , Conformación Molecular , Compuestos Organofosforados/química , EstereoisomerismoRESUMEN
A Pd-catalyzed asymmetric synthesis of Si-stereogenic dibenzosiloles is developed through enantioselective C-H bond functionalization of prochiral 2-(arylsilyl)aryl triflates. High chemo- and enantioselectivities are achieved by employing a Josiphos-type ligand under mild conditions.