| Through examine the expression of hypoxia - inducible factor -1a(HIF - 1a) and the microvessel density (MVD) in different pathology grading' s astrocytoma, analyze their relationships and the significance in clinical research.MethodsPatient selection: Tissue samples of astrocytic tumors ( n = 46 ) and brain tissues ( n = 7 ) were obtained from patients of brain tumors in the Second affiliated hospital of China Medical University between April, 1999 and June, 2002. All tumors were graded according to World Health Organization criteria (1993) , grade I : n =10, grade II: n =9, gradeIII : n = 15, gradeIV: n = 12.Immunohistochemistry: A total of 53 formalin - fixed and paraffin - embedded specimens was available for this study. Expression of HIF-1a and CD34 was immuno - histochemically investigated. Paraffin sections were cut at a 5 - um thickness, after repairing antigen and blocking nonspecific reactivity, the sections were incubated with anti - HIF -1 a and anti - CD34 monoclonal antibody for one night atthermostat and then with bio tin - conjugated second antibody foran additional 90 min. Positive signals were detected by the SP method with SP kit. Sections were also counterstained with hematoxylin.Result determination: The labeling indexs of HIF - 1 a were calculated microscopically field at a magnification of 400 x by counting tumor cells from 5 selected fields. Strong reactions in the nuclei were considered positive for HIF - 1 a. Microvessels density ( MVD) was determined by anti - CD34 immunostaining, First, select a microscopically field at a magnification of 40 x , search the hot - spots of micro - vessels, then calculated at a magnification of 200 x by 3 selected fields.Statistical methods: Student -1 test was used to compare the expression of HIF - 1 a or CD34 in primary astrocytic tumors and non ?tumor brain tissues. Nonparametric Spearman rank correlation coefficients were used to assess the degree of association between the his-topathologic grades of tumor, HIF - 1 a LI and M VD . Statistical significance was defined as p < 0. 05. The above analysis is progressed with statistics software SPSS.ResultsThe immunohistochemistry positive matter of HIF - la and CD34 assumes brown - yellow particles, in normal brain organization, there was no expression of HIF -la and saw a little of CD34 expression. With the malignant extent of astrocytic tumors gets higher, the expression of HIF - 1 a and CD34 goes up, The HIF - 1 a LI is : grade I ; 3.81 ± 2. 45, grade H : 10. 36 ±3. 43 , grade 1:24. 34 ± 10. 76, grade IV :30. 82 ± 13. 57; the CD34 positive microvessels number is: normal brain organization: 1. 67 ± 1. 29, grade I : 14. 20 ± 5.47, grade II :21.00 ±7. 03,grade III:28. 07 ± 10. 80,grade IV:40. 03 ± 15. 41. There was a positively correlation between HIF ?1 a LI and the tumor grade, (r= 0.79, P<0.01),MVD and the tumor grade, (r=0.70,P <0. 01) , HIF - la expression and MVD also showed a positively correlation,(r=0. 63, P<0.01).DiscussionHypoxia is a common feature of most solid cancers, tumours a-dopt two way to comform the low oxygen levels; glycolysis and angio-genesis. HIF is a transcription factor which present in most of human tissue in the hypoxia condition,it was be found by Semenza in his research of Erythropoietin, in 1991. HIF - 1 is a heterodimeric complex composed of two baic - helix - loop - lelix PAS - proteins: HIF -1 beta,which is constitutively expressed, HIF - 1 alpha, which is not present in normoxic cell but in duced under hypoxic conditions. The stability and activity of HIF - 1 o: are regulated by the interaction with various proteins, such as pVHL, p53, and p300/CBP as well as by post - translational modifications, hydroxylation, acetylation, and phos - phorylaion. When activated, it binds to the hypoxia - responsive element (HRE) and up -regulates the expression of several genes vascular endothelial growth factor ( VEGF) , erythropoietin (EPO) , eno-lase. The expression of HIF - 1 correlates with hypoxia - induced an-giogenesis a...
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