Expression of P-glycoprotein, multidrug resistance-associated protein, glutathione-S-transferase pi and p53 in canine transmissible venereal tumor

The overexpression of proteins P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP1), mutant p53, and the enzyme glutathione-S-transferase (GSTpi) are related to resistance to chemotherapy in neoplasms. This study evaluated the expression of these markers by immunohistochemistry in two groups of canine TVT, without history of prior chemotherapy (TVT1, n=9) and in TVTs presented unsatisfactory clinical response to vincristine sulfate (TVT2, n=5). The percentage of specimens positively stained for P-gp, MRP1, GSTpi and p53 were, respectively 88.8%, 0%, 44.5% and 22.2% in TVT1 and 80%, 0%, 80% and 0% in TVT2. In TVT1, one specimen presented positive expression for three markers and four specimens for two markers. In TVT2, three specimens expressed P-gp and GSTpi. In conclusion, the canine TVTs studied expressed the four markers evaluated, but just P-gp and GSTpi were significantly expressed, mainly at cytoplasm and cytoplasm and nuclei, respectively, either before chemotherapy as after vincristine sulfate exposure. Future studies are needed to demonstrate the function of these two markers in conferring multidrug resistance (MDR) or predict the response to chemotherapy in canine TVT.A superexpressão das proteínas glicoproteína-P (Gp-P), proteína associada à resistência à múltiplas drogas 1 (MRP1) e p53 mutante e a enzima glutationa-S-transferase pi (GSTpi) está relacionada com resistência à quimioterapia em neoplasias humanas e caninas. Este estudo avaliou a expressão, por meio da imuno-histoquímica desses marcadores em espécimes de TVT caninos sem histórico de quimioterapia prévia (TVT1, n=9) e em TVT caninos que apresentaram resposta clínica insatisfatória ao sulfato de vincristina (TVT2, n=5). A porcentagem de espécimes positivos para Gp-P, MRP1, GSTpi e p53 foram, respectivamente 88,8%, 0%, 44,5% e 22,2% no grupo TVT1 e 80%, 0%, 80% e 0% no grupo TVT2. No TVT1, um espécime apresentou expressão positiva para três marcadores e quatro para dois marcadores. No TVT2, três espécimes expressaram a Gp-P e GSTpi. Em conclusão, os TVTs caninos estudados expressaram os quatro marcadores avaliados, no entanto apenas a Gp-P e GSTpi foram significativamente expressas, principalmente no citoplasmas e no citoplasma e no núcleo, respectivamente, tanto antes da quimioterapia quanto após à exposição ao sulfato de vincristina. Estudos futuros são necessários para demonstrar a função desses dois marcadores em conferir resistência à multiplas drogas (RMD) ou predizer a resposta a quimioterapia no TVT canino.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal do Rio Grande do Sul Faculdade de Veterinária Departamento de Medicina AnimalUniversidade Estadual Paulista Faculdade de Ciências Agrárias e Veterinárias Departamento de Clínica e Cirurgia VeterináriaUniversidade Federal de Sergipe Núcleo de Medicina VeterináriaUniversidade Estadual Paulista Faculdade de Ciências Agrárias e Veterinárias Departamento de Clínica e Cirurgia VeterináriaFAPESP: 06/52527-

A High-Resolution Neutron-Diffraction Study Of The Structure Of Amorphous Hydrogenated Carbon, a-CH

Current structural models for amorphous hydrogenated carbon (a-C:H) are called into question on the basis of neutron-diffraction experimental work carried out al the ISIS pulsed neutron source (UK) on a-C:H. The nature of the neutron source allows the collection of data over an exceptionally wide dynamic range that ensures a real-space resolution sufficient to allow direct observation, for the first time, of contributions from the principal C-C bond types. The data also reveal details of the C-H correlations, and the presence of trapped molecular hydrogen

The Structure Of Amorphous Hydrogenated Carbon By Neutron-Diffraction

Neutron diffraction data from a large, off-substrate sample of amorphous hydrogenated carbon (a-C:H) is presented and discussed. The material is prepared using a fast-atom deposition system using acetylene as the precursor gas. The experiments were performed on the ISIS pulsed neutron source (Rutherford Appleton Laboratory, UK) which is capable of yielding data over an exceptionally wide dynamic range; this ensures a real-space resolution sufficient to resolve directly, for the first time, contributions from the principle C-C bond types. Precise details on the C-H correlations are also revealed by the data, including the presence of molecular hydrogen trapped within distorted spheroidal cages. Quantitative complementary data on the vibrational states of the bonded hydrogen, derived from inelastic neutron scattering (INS) using a simple force-field model, is also presented. In particular, the INS data is used to provide a reliable estimate of the CH:CH2 ratio

The Effect Of Hydrogen Dilution On The Interatomic Bonding Of Amorphous Hydrogenated Silicon - Carbon

The effect of hydrogen dilution of the precursor gas mixture on the local bonding environment in glow-discharge deposited a-Si:C:H has been studied by neutron diffraction and inelastic neutron scattering. The neutron diffraction results show a large increase in the silicon-carbon bonding upon hydrogen dilution, at the expense of silicon-silicon bonding. The inelastic neutron scattering provides complementary information on the hydrogen bonding environment. The hydrogen is predominantly bonded in SiH and SiH2 groups, with a large increase in the SiH2 group concentration occurring upon hydrogen dilution. The data presented here show that SiH3 and CH(n) groups are present as a very small fraction of H bonding sites, if at all