Alquilação redutiva da quitosana a partir do glutaraldeído e 3-amino-1-pr

Chitosan derivatives were prepared by reductive alkylation using glutaraldehyde and 3-amino-1-propanol. The reducing agent used was the sodium borohydride. Tests of solubility, stability and viscosity were performed in order to evaluate these parameters effects in the reaction conditions (molar ratio of the reactants and presence of nitrogen in the reaction system). The molecular structure of commercial chitosan was determined by infrared (IR) and hydrogen nuclear magnetic resonance spectroscopy (1H NMR). The intrinsic viscosity and average molecular weight of the chitosan were determined by viscosimetry in 0.3 M acetic acid aqueous solution 0.2 M sodium acetate at 25 ºC. The derivatives of chitosan soluble in aqueous acidic medium were characterized by 1H NMR. The rheological behavior of the chitosan and of the derivative of chitosan (sample QV), which presented the largest viscosity, were studied as a function of polymer concentration, temperature and ionic strength of the medium. The results of characterization of the commercial chitosan (the degree of deacetylation obtained equal 78.45 %) used in this work confirmed a sample of low molar weight (Mv = 3.57 x 104 g/mol) and low viscosity (intrinsic viscosity = 213.56 mL/g). The chemical modification of the chitosan resulted in derivatives with thickening action. The spectra of 1H NMR of the soluble derivatives in acid aqueous medium suggested the presence of hydrophobic groups grafted into chitosan in function of the chemical modification. The solubility of the derivatives of chitosan in 0.25 M acetic acid aqueous solution decreased with increase of the molar ratio of the glutaraldehyde and 3-amino-1-propanol in relation to the chitosan. The presence of nitrogen and larger amount of reducing agent in reaction system contributed to the increase of the solubility, the stability and the viscosity of the systems. The viscosity of the polymeric suspensions in function of the shear rate increased significantly with polymer concentration, suggesting the formation of strong intermolecular associations. The chitosan presented pseudoplastic behavior with the increase in polymer concentration at a low shear rate. The derivative QV presented pseudoplastic behavior at all concentrations used and in a large range of shear rate. The viscosity of chitosan in solution decreased with an increase of the temperature and with the presence of salt. However, there was an increase of the viscosity of the chitosan solution at higher temperature (65 ºC) and ionic strength of the medium which were promoted by hydrophobic associating of the acetamide groups. The solutions of the chitosan derivatives (sample QV) were significantly more viscous than chitosan solution and showed higher thermal stability in the presence of salt as a function of the hydrophobic groups grafted into chitosan backbone

Imunoexpressão de vegf-c, vegfr-3 e hif-1α e mensuração da densidade linfática em carcinomas epidermóides de lábio inferior metastáticos e não-metastáticos: uma relação com parâmetros clinicopatológicos e prognósticos

Squamous cell carcinoma of the lower lip is among the most common malignant tumors of the oral and maxillofacial region, with good prognosis in more than 90% of patients with 5-year survival. In these carcinomas, the development of lymph node metastasis decreases the prognosis and it has been associated with the formation of new lymphatic vessels. It has been suggested the important role of vascular endothelial growth factor-C (VEGF-C), the receptor type 3 VEGF (VEGFR-3) and hypoxia-induced factor 1 (HIF-1) in this process. The aim of this study was to evaluate the immunoexpression of VEGF-C, VEGFR-3 and HIF-1α and correlate with intra and peritumoral lymphatic density in squamous cell carcinomas of the lower lip metastatic and non-metastatic. The sample consisted of 50 cases of squamous cell carcinoma of lower lip, of which 25 had regional lymph node metastasis and 25, absence of metastasis. The percentages of cells immunostained for VEGF-C, VEGFR-3 and HIF-1α in front of tumor invasion and in the center of tumor were evaluated. Microvessel density lymphatic (MDL) was determined by the counting of lymph microvessels immunostained by the anti-D2-40 in five fields (200×), in an area of evaluation with 0.7386 mm2. The invasion of the lymph vessels by malignant cells was also evaluated. Immunostaining was correlated with the presence and absence of metastasis, TNM clinical stage, local recurrence, disease outcome (remission of injury or patient death) and histological grading. The analysis of intra and peritumoral lymphatic density showed no significant association with clinicopathological parameters and immunoexpressions of VEGF-C, VEGFR-3 and HIF-1α (p > 0,05). There was a weak positive correlation, significant, between intra and peritumoral lymphatic density (r = 0,405; p = 0,004). VEGF-C showed no significant association with clinicopathological and prognosis parameters (p > 0,05). For VEGFR-3, there was scarce membrane staining and intense and homogenous cytoplasmic staining in neoplastic cells. Percentage of positive cytoplasmic VEGFR-3 in center of tumor, exhibited a statistically significant association with metastasis (p = 0,009), patient death (p = 0,008) and histological grades of malignancy proposed by Bryne et al. (1992) (p = 0,002) and World Health Organization (p = 0,003). A low positive correlation was statistically significant between the immunoreactivity of VEGFC and VEGFR-3 cytoplasmic (r = 0,358; p = 0,011) and between the percentage of positive cytoplasmic VEGFR-3 in front of tumor invasion and in the center of the tumor (r = 0,387; p = 0,005) was also demonstrated. There was no association between HIF-1α, clinicopathological and prognosis parameters, and VEGF-C and VEGFR-3. The percentage of nuclear positivity for HIF-1α was significantly higher in cases without invasion of peritumoral lymphatic (p = 0,040). Based on the results we can conclude that most cytoplasmic expression of VEGFR-3 in center of tumor in metastatic cases, high degree of malignancy and poorly differentiated, contributes to poor outcome of squamous cell carcinoma of the lower lip, including patient death. Intra and peritumoral lymphatic density seems to be not associated with lymph node metastasis in these carcinomas