RESUMO
Studies of the molecular mechanisms of esophageal cancer development have to be carried out on sufficient amount of tumor material, obtained under conditions of controlled exposure to carcinogenic factors. Esophageal cancer models on laboratory animals serve an indispensable source of this material. One of these models is esophageal cancer induction in rats by N-nitroso compound precursors. Despite adequate reproduction of human esophageal cancer, this model in fact has not been used since the 1990ies. Re-examination of esophageal cancer model, induced by N-nitrososarcosine ethyl ester precursors, is carried out and its efficiency in induction of squamous cell carcinoma is confirmed.
Assuntos
Carcinoma de Células Escamosas/patologia , Neoplasias Esofágicas/patologia , Nitrosaminas/toxicidade , Animais , Carcinoma de Células Escamosas/induzido quimicamente , Neoplasias Esofágicas/induzido quimicamente , Carcinoma de Células Escamosas do Esôfago , Masculino , Ratos , Ratos WistarRESUMO
Excited-state absorption (ESA) in various bismuth-doped fibers (BDFs) was investigated. No significant ESA in IR emission bands of Bi-doped germanosilicate and phosphosilicate fibers was found. Considerable ESA was observed in Bi-doped aluminosilicate fibers at 800-1700 nm. The ESA spectra of the aluminosilicate BDFs with different bismuth concentration were measured at room and 77 K temperature. Significant dependence of the ESA on the bismuth concentration and the fiber temperature was found.
RESUMO
An efficient CW bismuth fiber laser operating around 1.46 µm with an efficiency of >50% and an output power of >20 W has been developed on a bismuth-doped GeO(2)-SiO(2) fiber. The laser demonstrates weak dependence of the output power on temperature in comparison with bismuth lasers operating near 1.15 and 1.3 µm. The laser generation has been obtained in the range 1.39 to 1.54 µm. The first linearly polarized bismuth-doped fiber laser at 1.46 µm based on a PANDA-type fiber has been demonstrated.
Assuntos
Bismuto/química , Lasers , Fenômenos Ópticos , Silicatos/química , TemperaturaRESUMO
Here, we review the problems of neurotrophic factors' folding, the role of its precursors (proneurotrophins) and the contribution of elements deleted during its maturation (propeptides) in biological functioning of these growth factors.
Assuntos
Fatores de Crescimento Neural/fisiologia , Dobramento de Proteína , Precursores de Proteínas/fisiologia , Animais , HumanosRESUMO
A 24 dB gain bismuth-doped fiber amplifier at 1430 nm pumped by a 65 mW commercial laser diode at 1310 nm is reported for the first time (to our knowledge). A 3 dB bandwidth of about 40 nm, a noise figure of 6 dB, and a power conversion efficiency of about 60% are demonstrated. The temperature behavior of the gain spectrum is examined.
RESUMO
Glutamyl endopeptidase from Bacillus intermedius (BIGEP) is a secretory serine proteinase specifically hydrolyzing peptide bonds involving alpha-carboxyl groups of glutamic and aspartic acids. In this work, different BIGEP forms (full-length precursor, precursor without signal peptide and mature part) were expressed in Escherichia coli and the process of enzyme maturation was studied in vitro. BIGEP precursor renaturation leads to autocatalytic hydrolysis of the propeptide at Glu(-16). At the same time, the enzyme activation requires the complete removal of the prosequence by other proteinases. The mature part of BIGEP cannot be activated, which indicates that the propeptide is required for the active protein formation. The data obtained allowed us to apply directed mutagenesis of the processing site to obtain a BIGEP form that matured autocatalytically. This approach makes it possible to produce the enzyme without extrinsic proteinases, which is a prerequisite for using it in limited hydrolysis of proteins and peptides.
Assuntos
Bacillus/enzimologia , Bacillus/metabolismo , Serina Endopeptidases/metabolismo , Animais , Bacillus/genética , Células Cultivadas , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Renaturação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Serina Endopeptidases/química , Serina Endopeptidases/genética , Especificidade por SubstratoAssuntos
Adaptação Psicológica , Educação Profissionalizante , Militares , Psicologia Militar , Universidades , Educação Profissionalizante/métodos , Educação Profissionalizante/organização & administração , Educação Profissionalizante/tendências , Militares/educação , Militares/psicologia , Testes Psicológicos , Federação Russa , Universidades/organização & administração , Universidades/normas , Universidades/tendênciasRESUMO
Optical fibers with bismuth-doped silicate and germanate glass cores were fabricated by the modified chemical vapor deposition technique (solution and vapor-phase Bi incorporation). The fibers revealed an efficient luminescence with a maximum in the 1050-1200 nm spectral range, FWHM up to 200 nm, and a lifetime of the order of 1 ms.
RESUMO
Germania-glass-core silica-glass-cladding single-mode fibers (deltan as great as 0.143) with a minimum loss of 20 dB/km at 1.85 microm were fabricated by modified chemical-vapor deposition. The fibers exhibit strong photorefractivity, with type IIa index modulation of 2 x 10(-3). A Raman gain of 300 dB/(kmW) was determined at 1.12 microm. Only 3 m of such fibers is sufficient for constructing the 10-W Raman laser at 1.12 microm with a 13-W pump at 1.07 microm.