ABSTRACT
Mesoporous silica SBA-15 with a small organic molecular (1,8-Naphthalimide) was synthesized and used as matrix for MALDI-TOF-MS ( Matrix-assisted laser desorption/ionization time of flight mass spectrometry) analysis. A modified SBA-15 matrix, SBA-15-NA (1,8-Naphthalimide) was synthesized by covalently attaching SBA-15 to an 1 , 8-naphthalimide formed by 1 , 8-naphthalic anhydride and 3-( trimethoxysilyl) propylamine. The mass spectra obtained with SBA-15-NA exhibited less background interference ions, higher desorption/ionization efficiency, and higher peak intensity. The matrix was initially prepared in methanol and mixed with analyte at a 1∶1 volume ratio in vial. The solution of mixture was at a 10∶1 concentration ratio of matrix/analyte on a stainless steel target and allowed to air dry. The method was used to analyze various types of low molecular weight ( less than 500 ) chemical compounds such as monosaccharides, amino acids, phytohormones, drugs. Under the optimal conditions, it gave low detection limit of 1×10-9 g/L (Leucine, S/N=5) and good reproducibility (≤30%). The modified mesoporous silica materials have been employed in the urinary study for direct detection of metabolites.
ABSTRACT
Objective To establish a stable implanted model of VX2 rabbit brain tumor, and to evaluate the pathological and imaging features and tumor angiogenesis. Methods Thirty New Zealand white rabbits were implanted with 100 ?l viable VX2 tumor cells (107/ml) through a hole 5 mm to the right of the sagittal suture and 5 mm posterior to the coronal suture bored by a dental drill. MRI was performed every ~2 days after 7 days of implantation to evaluate the growth of the tumor, and perfusion CT studies were performed in different days of tumor growth. After that the animals were sacrificed on days 14, 18, 22, 26, and 30 of tumor implantation. 2% Evans blue (2 ml/kg) was given intravenously in 16 of these animals ~1 hour prior to sacrifice to detect the breakdown of the blood-brain barrier (BBB). The specimens of the rabbit brains were examined pathologically and histologically. VEGF and MVD were evaluated in immunohistochemical examination. Results Of the 22 animals included into the study, the tumor grew in 20 animals, which could be seen clearly on MR imaging. Pathologic examination showed characteristics of squamous carcinoma. VEGF was expressed in all tumors with the mean rate of positive cells of (52.51?19.15)% (19.5%-92.9%). Mean MVD was (51.30?14.42)pice piece/microscope (25-81 pice piece/microscope). Using Pearson′s linear correlation analysis, positive correlation was found between tumor growth time and volume (r=0.791, P=0.000), between MVD and tumor growth time (r=0.875, P=0.000), and between MVD and tumor volume (r=0.901, P=0.000), respectively. Spearman′s rank correlation analysis showed positive correlation between VEGF grade and blue stain of the tumor (r_s=0.594, P=0.015). Conclusion A stable model of VX2 rabbit brain tumor has been established with the method of skull drilling. The method was simple and easy to use, with a high tumor growth rate and remarkable angiogenesis. The model is helpful for the pathological and radiological study of tumor angiogenesis.
