A convenient method for the synthesis of polyamides containing N-methylpyrrole (Py) and N-methylimidazole (Im) in solution has been developed. Most of the building blocks have been prepared by a haloform reaction in a simple way that column chromatography can be avoided. By use of the DCC/HOBT coupling reaction, the building blocks prepared have been effectively connected to construct a variety of subchains and polyamides without employing amino protection and deprotection. By use of the present method, an eight-ring polyamide, PyPyPyPygammaPyImImPybetaDp (gamma is gamma-aminobutyric acid, beta is beta-alanine, Dp is N, N-dimethylpropyldiamine), has been synthesized by the coupling of two four-ring subchains in one step.

The results suggest a distinctly different mutation spectrum of MMR genes between northern and southern Chinese populations and call for a systematic, nationwide study to facilitate the design of a MMR gene mutation detection strategy tailored for individual populations in China.

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Vascular endothelial growth factor (VEGF), a potent angiogenic and vascular permeability factor, is important in the angiogenesis of glioblastoma. A major difference between pilocytic astrocytoma, a grade I tumor, and the grade II fibrillary astrocytoma is the vascular proliferation, highly vascularized stroma, and great propensity for cyst formation in the former. In order to explore factors regulating such angiogenesis and cyst formation in pilocytic astrocytoma, we examined expression of VEGF and its receptors (KDR and Flt-1) using in situ hybridization. In all 14 cases a high level of VEGF transcripts could be demonstrated. These were found in specific regions, namely, in the tumor cyst wall, in areas of hyaline cystic degeneration, in stellate reticulated astrocytes around microcysts in the biphasic compact and loose areas, and in tumor cells with degenerative pleomorphic multicoated nuclei. KDR and Flt-1 were expressed in the tumor vasculature, with particularly high levels seen in coiled young proliferating vessels, especially those in the cyst wall. Given the known angiogenic and vascular permeability activities of VEGF, we propose that VEGF plays an important role in molding the characteristic morphologic features of this tumor, namely, the formation of cysts, microcystic pattern, hyaline cystic degeneration, hyaline vessels, and vascular proliferation. Mechanisms that block the VEGF pathway could constitute a potential therapeutic strategy for the treatment of this tumor.