Feasibility of synchrotron radiation computed tomography on rats bearing glioma after iodine or gadolinium injection

The purpose of this work was to demonstrate the feasibility of a new imaging technique called synchrotron radiation computed tomography (SRCT). This technique leads to a direct assessment of the in vivo concentration of an iodine- or gadolinium-labeled compound. Rats bearing C6 glioma were imaged by MRI prior to the SRCT experiment. The SRCT experiments were performed after a 1.3 g I/kg (n = 5) or a 0.4 g Gd/kg (n = 5) injection. Finally, brains were sampled for histology. The SRCT images exhibited contrast enhancement at the tumor location. Ten minutes after injection, iodine and gadolinium tissular concentrations were equal to 0.80 ( ± 0.40) mg/cm³ and 0.50 ( ± 0.10) mg/cm³, respectively in the peripheral area of the tumor (respective background value: 0.20 ± 0.02 to 0.10 ± 0.01). Correlation to MRI and histology revealed that the contrast uptake occurred in the most vascularized area of the tumor. The present study summarizes the feasibility of in vivo SRCT to obtain quantitative information about iodine and gadolinium-labeled compounds. Beyond brain tumor pathology, the SRCT appears as a complementary approach to MRI and CT, for studying iodine- and gadolinium-labeled compounds by the direct achievement of the tissular concentration value in the tissue. Received: 8 September 1999; Revised: 3 May 2000; Accepted: 4 May 2000     

胶质瘤促血管生成素2基因表达的临床意义（附52例分析）

目的　探讨胶质瘤促血管生成素2 (Ang2) 基因在脑胶质瘤的表达及其临床意义。方法　采用逆转录聚合酶链反应(RT PCR) 和链酶亲和素过氧化物酶复合物SABC法检测52例人脑胶质瘤和8例正常脑组织中Ang2基因表达。结果　50 例脑胶质瘤和8 例正常脑组织均可表达Ang2 mRNA片段。高恶度胶质瘤Ang2 mRNA及蛋白表达显著高于低恶度胶质瘤(P<0 01); 低恶度胶质瘤Ang2 mRNA及蛋白表达显著高于正常脑组织(P<0 05)。免疫组化染色显示, Ang2蛋白主要分布在高恶度胶质瘤组织的瘤细胞和内皮细胞, 低恶度胶质瘤呈低水平表达, 正常脑组织不表达。结论　Ang2的表达与胶质瘤的分级密切相关, 可能对胶质瘤的恶性演进起促进作用。     

胶质瘤促血管生成素2基因表达与血管生成关系的实验研究

目的探讨胶质瘤促血管生成素2(Ang2)表达与血管生成的关系。方法采用RT-PCR检测52例人脑胶质瘤和8例正常脑组织中Ang2基因表达;CD34单克隆抗体组织化学染色显示微血管,用微血管计数(MVC)测定肿瘤血管生成。结果50例脑胶质瘤和8例正常脑组织均可表达Ang2 mRNA片段。Ang2 mRNA表达与脑胶质瘤的血管生成呈正相关(r=0.821,P<0.01);高恶度胶质瘤Ang2mRNA表达、MVC分别显著高于低恶度胶质瘤(P<0 01);低恶度胶质瘤Ang2mRNA表达、MVC均显著高于正常脑组织(P<0.01)。结论Ang2可能通过参与胶质瘤血管生成,对胶质瘤的恶性进展起促进作用。     

RNA干扰抑制胰岛素样生长因子-1表达并诱导胶质瘤细胞凋亡

目的研究RNA干扰效应对胶质瘤C_6细胞株胰岛素样生长因子-1(IGF-1)基因表达的抑制作用及其对C_6细胞凋亡诱导的作用。方法体外化学合成靶向IGF-1基因的小干扰RNA(siRNA),采用脂质体法将siRNA以不同浓度梯度转染C_6细胞株,设非特异的siRNA阳性对照组和未转染siRNA的阴性对照组；同时使用绿色荧光素标记的siRNA异硫氰酸荧光素(FITC)-siRNA转染细胞,于荧光显微镜下观察siRNA转染效率；逆转录聚合酶链反应(RT-PCR)半定量检测siRNA对IGF-1基因表达的抑制作用；流式细胞术检测siRNA诱导细胞凋亡作用。结果荧光显微镜下荧光素标记的siRNA转染组可见到细胞内清晰的绿色荧光,脂质体Oligo- fectamine~(TM)2000的转染效率可＞95%；化学合成的siRNA明显抑制IGF-1 mRNA的表达,各特异性siRNA不同浓度转染组IGF-1 mRNA表达水平可下调约40%～70%,流式细胞术检测转染IGF1-siRNA细胞凋亡率为14．14%,明显高于对照组的0．95%。结论在细胞水平上,化学合成的靶向IGF-1的siRNA可明显抑制IGF-1基因的表达,引致胶质瘤细胞凋亡率明显上升,为进一步利用RNA干扰进行胶质瘤的基因治疗研究奠定基础。     

端粒酶反义寡核苷酸及顺铂对恶性脑胶质瘤治疗的协同作用

目的观察端粒酶反义寡核苷酸(ODN)及顺铂对恶性脑胶质瘤治疗的协同作用.方法用15例Ⅲ、Ⅳ级端粒酶活性阳性表达的脑恶性胶质瘤制备单细胞悬液并原代培养,以5μmol/L端粒酶反义ODN抑制恶性胶质瘤细胞端粒酶活性后,用不同浓度顺铂处理细胞.流式细胞仪检测处理前后胶质瘤细胞PCNA、TUNEL阳性百分率变化情况.结果端粒酶反义ODN作用于恶性胶质瘤细胞72h后,TRAP法检测端粒酶活性转为阴性,此时0.3μg/mL顺铂即可对胶质瘤细胞有明显抑制增殖、促进凋亡作用.结论端粒酶反义ODN能抑制端粒酶活性,增加恶性胶质瘤细胞对顺铂的敏感性,与顺铂在治疗恶性胶质瘤细胞过程中有协同作用.     

COX-2 选择性抑制剂Celecoxib 治疗胶质瘤的体内实验研究

 目的 探讨选择性环氧化酶-2抑制剂Celecoxib(塞来昔布)对C6胶质瘤生长抑制的体内实验研究。方法 将成瘤小鼠分为对照组和治疗组，应用肿瘤HE染色法、肿瘤生长曲线、前列腺素E2(PGB)检测及电镜检查方法观察Celecoxib对小鼠移植瘤的作用。结果 HE染色和电镜可见治疗组血管破坏、细胞坏死和凋亡，PGE2检测及肿瘤生长曲线分析有统计学意义，P<0．05。结论 Celecoxib能够抑制COX-2活性。降低PGB合成，Celecoxib对C6胶质瘤生长具有抑制作用，对胶质瘤的治疗有重要意义。     

逆转录PCR方法检测HoxA族基因在胶质瘤细胞C6中的表达

背景与目的：同源盒基因是生物发育调节的主控基因，具体作用体现在调控DNA的转录过程。近年来已发现多种恶性肿瘤中有不同种类的同源盒基因异常表达。胶质瘤中同源盒基因的表达尚未全部确定。本研究旨在观察胶质瘤细胞C6中异常表达的同源盒基因中HoxA族基因的种类。方法：应用HoxA族基因特异引物，对原代培养大鼠正常脑组织星形胶质细胞和胶质瘤C6细胞进行逆转录PCR。结合图像分析法分组检测HoxA族11种基因mRNA的表达水平。统计分析比较两种细胞中HoxA族基因表达水平。Hox基因表达水平用基因／β-肌动蛋白（β—actin）灰度比值表示。结果：HoxA3、A5、A6、A7、A9、A11、A13基因在正常脑组织和C6细胞中表达没有显著差异；HoxA1基因在正常大鼠和胶质瘤细胞C6中表达虽有显著差异，但均为弱表达；HoxA4基因在正常脑组织中弱表达，在C6细胞中有明显表达，二者比较，差异显著（P〈0.01）；HoxA2、HoxA10基因在正常大鼠脑组织中未见表达，在胶质瘤细胞c6中有明显表达。结论：HoxA2、A4、A10基因mRNA表达增高，可能与胶质瘤的发生、发展相关。     

中华眼镜蛇毒组分C与几种临床化疗药体外对人胶质瘤株作用的差异研究

背景与目的：脑胶质瘤是常见的颅内肿瘤，占脑恶性肿瘤的50％以上，化疗作为综合治疗的一项重要手段，仍存在效果不理想、易耐药等问题。本文就研究中华眼镜蛇毒组分C（Fraction C from Naja Naja Actra Venom，NNAV．FC）体外对人胶质瘤细胞株U-251的细胞毒性作用，并与几种临床脑肿瘤化疗用药进行比较，以求为脑胶质瘤的治疗提供新的化疗药物。方法：应用MTT法．观察NNAV．FC人胶质细胞瘤株U-251的细胞毒作用、量效关系等，并与依托泊苷（vp=16、鬼臼乙叉苷、Vepesid）、卫萌（替尼泊苷、鬼臼甲叉甙vm-26，Teniposide）、顺铂（Cisplatin、CDDP）、卡铂（Carboplatin）、五氟尿嘧啶（5-FU）等对上述细胞的细胞毒作用进行比较。结果：FC对人胶质瘤细胞有明显的抑制作用，其24及48h的IC50分别为5．76和7．19μg／ml，且呈良好的量效关系。结论：在本实验中，FC能有效抑制胶质瘤细胞株的生长，抑制作用与浓度呈正相关，与临床胶质瘤化疗药相比较。FC是有效地抑制胶质瘤细胞生长的药物。     

An insight into electrical resistivity of white matter and brain tumors

BackgroundThere is a lack of information regarding electrical properties of white matter and brain tumors.ObjectiveTo investigate the feasibility of in-vivo measurement of electrical resistivity during brain surgery and establish a better understanding of the resistivity patterns of brain tumors in correlation to the white matter.MethodsA bipolar probe was used to measure electrical resistivity during surgery in a prospective cohort of patients with brain tumors. For impedance measurement, the probe applied a constant current of 0.7 μA with a frequency of 140 Hz. The measurement was performed in the white matter within and outside peritumoral edema as well as in non-enhancing, enhancing and necrotic tumor areas. Resistivity values expressed in ohmmeter (Ω1m) were compared between different intracranial tissues and brain tumors.ResultsNinety-two patients (gliomas WHO II:16, WHO III:10, WHO IV:33, metastasis:33) were included. White matter outside peritumoral edema had higher resistivity values (13.3 ± 1.7 Ω1m) than within peritumoral edema (8.5 ± 1.6 Ω1m), and both had higher values than brain tumors including non-enhancing (WHO II:6.4 ± 1.3 Ω1m, WHO III:6.3 ± 0.9 Ω1m), enhancing (WHO IV:5 ± 1 Ω1m, metastasis:5.4 ± 1.3 Ω1m) and necrotic tumor areas (WHO IV:3.9 ± 1.1 Ω1m, metastasis:4.3 ± 1.3 Ω1m), p=<0.001. No difference was found between low-grade and anaplastic gliomas, p = 0.808, while resistivity values in both were higher than the highest values found in glioblastomas, p = 0.003 and p = 0.004, respectively.ConclusionsThe technique we applied enabled us to measure electrical resistivity of white matter and brain tumors in-vivo presumably with a significant effect with regard to dielectric polarization. Our results suggest that there are significant differences within different areas and subtypes of brain tumors and that white matter exhibits higher electrical resistivity than brain tumors.     

MiR-124-3p suppresses glioma aggressiveness via targeting of Fra-2

Malignant glioma is the most common and deadly primary brain tumor in adults. However, the mechanisms underlying the malignancy of glioma remain unclear. In the present study, we found that Fos-related antigen-2 (Fra-2) was overexpressed in most glioma cells, and knockdown of Fra-2 prevented cell proliferation, migration, and invasion. Mechanistically, Fra-2 silencing led to a significant reduction in cell-cycle drivers (Cyclin D1 and Cyclin E1), one invasion-associated gene (MMP9), the mesenchymal marker (Vimentin), and induction of the epithelial marker (E-cadherin). Further study confirmed that miR-124-3p decreased the expression of Fra-2 via directly targeting the 3′-UTR, and transfection with miR-124-3p in glioma cells inhibited expression of the above cell-cycle and EMT promoters. Phenotypic experiments also showed that overexpression of Fra-2 weakened the inhibitory effects of miR-124-3p on the proliferation, migration, and invasion of glioma cells. In addition, Fra-2 knockdown impaired the malignant phenotypes enhanced by miR-124-3p inhibition, which suggested a crucial role for the miR-124-3p/Fra-2 pathway in glioma development. Consistently, high expression of Fra-2 was closely associated with low miR-124-3p level and indicated a poor prognosis in patients with glioma. In conclusion, this study indicates the existence of an aberrant miR-124-3p/Fra-2 pathway that results in glioma aggressiveness, which suggests novel therapeutic opportunities for this fatal disease.