Studies on the 67Ga uptake mechanism by Ehrlich ascites tumor cells

In order to obtain more information concerning the mechanism of Gallium (67Ga) accumulation in malignant tissue, an investigation was carried out using Ehrlich ascites tumor cells. Chlorpromazine, a phospholipid stabilizer decreased the uptake of 67Ga and Calcium 45 (45Ca) by the cells at low dose, but increased them at high dose. On the other hand, the uptake of both radionuclides by the cells was inhibited by ruthenium red, a Ca ATPase inhibitor in a dose dependent manner. The time course of 67Ga and 45Ca uptake were quite different from each other. Moreover, the subcellular distribution patterns of 67Ga and 45Ca were also different from each other; 67Ga accumulated in the lysosomal fraction and 45Ca mainly in the mitochondrial fraction. These results suggest that there may be a commonality for 67Ga and 45Ca uptake by the tumor cells, whereas the behaviour of these two radionuclides in the cells is dissimilar.     

67Ga uptake and heparan sulfate content of Ehrlich solid tumor in mice

The relationship between ⁶⁷Ga uptake and heparan sulfate (HS) content in Ehrlich solid tumor (EST) of mice was investigated, and the effect of cyanomethylamine, papain, streptozotocin, or bleomycin pretreatment on ⁶⁷Ga uptake in EST was studied. ⁶⁷Ga uptakes in EST and kidney were much higher than other tissues, and these tissues also contained large amounts of HS. ⁶⁷Ga uptakes and HS synthesis in the EST were inhibited by pretreatment with cyanomethylamine or papain (inhibitors of fibrosis). Parallel reductions of ⁶⁷Ga uptake and HS synthesis in EST were observed in EST transplanted into streptozotocin-induced diabetic mice. The weight of EST in the bleomycin-injected group was decreased to less than half of the control, but no effect was observed on ⁶⁷Ga uptake per gram of EST. These results suggest that ⁶⁷Ga uptake in the tumor and inflammatory lesions are related to the quantity of HS in these tissues, and the correlation between the uptake of ⁶⁷Ga and the rate of cellular proliferation is secondary.     

Experimental evidence for the probable involvement of calcium ion transport in 67Ga uptake by tumour cells

The study of ⁶⁷Ga-citrate uptake and calcium transport in Ehrlich ascites tumour cells seems to indicate that their peculiar characteristic of increased permeability to extracellular calcium ion might be responsible for their ⁶⁷Ga accumulation. Experiments performed under different conditions of extracellular calcium, temperature, and presence of ionophore and other plasma membrane modifying agents such as lanthanum appear to corroborate this hypothesis.     

The relationship between 67Ga accumulation and ATP metabolism in tumor cells in vitro

Previously, we reported that the deposition of ⁶⁷Ga into malignant tumors may be a sensitive index of proliferative activity in tumor cells. For the purpose of elucidation of this hypothesis, we investigated the relationship between the accumulation of ⁶⁷Ga into malignant tumor cells and the intra cellular ATP metabolism in vitro.The uptake of ⁶⁷Ga into tumor cells was inhibited by adding NaF which is an inhibitor of ATP production. Furthermore, the uptake of ⁶⁷Ga into tumor cells was strongly inhibited by adding ouabain which is a specific inhibitor of Na⁺–K⁺-ATPase. From these in vitro results, it was concluded that there is a correlation between ⁶⁷Ga uptake and intra cellular ATP metabolism in tumor cells.     

Accumulation of gallium-67 within mature and immature teratoma in pediatric patients: investigation for the uptake mechanism

OBJECTIVE: We encountered cases of mature and immature teratoma with positive uptake of (67)Ga. The objective of this study is to investigate the mechanism of (67)Ga accumulation within mature and immature teratomas by comparing the findings of gallium scan, computed tomography (CT), and autoradiography of surgical specimens with the pathological findings. METHODS: The subjects comprised 14 children who underwent surgical resection for intra-abdominal mature and immature teratomas, which were histologically proved to be of the mature and immature subtype. Their age ranged from 24 days to 14 years. The origins of the mature teratomas consisted of seven ovaries including one bilateral case, two retroperitoneal, and two sacrococcygeal regions. The origins of the immature teratomas were retroperitoneum in two cases, an ovary and a sacrococcygeal region. Complete surgical excision was feasible in all children. They underwent both gallium scan and CT prior to surgery. Single-photon emission computed tomography was added in some cases. For two gallium-positive cases, radiography and scintigraphy (autoradiography) of the resected specimen were performed. RESULTS: Of the 14 children, 5 (one with immature and four with mature subtype) showed positive (67)Ga uptake within tumors, which originated from the retroperitoneum in the 3 boys, and from the ovary in the 2 girls. All had typical CT findings of teratoma, including calcifications, fat components, cystic areas, and solid parts. (67)Ga accumulation in the four mature teratomas appeared discretely strong, and was considered to correspond with intralesional calcifications. However, in the remaining one immature teratoma, the gallium distribution was diffuse within the tumor. The comparison between radiography and autoradiography of the resected mature teratomas confirmed the correlation between the intralesional calcifications and areas of (67)Ga accumulation. CONCLUSIONS: A high-uptake ratio of (67)Ga in benign teratoma was indicated. A close correlation between gallium scan and CT helps to ascertain whether (67)Ga uptake results from malignant and/or immature elements, or mature tissue components.     

Effects of chronic exposure to acidic environment on the response of tumor cells to radiation

Purpose: The influence of short-term exposure to an acidic environment on the radiosensitivity of tumor cells has been extensively explored, but the implication of chronic exposure to an acidic environment for the response of tumor cells to radiation has not been fully elucidated. This study aimed to investigate the effects of chronic pre- and post-irradiation exposure of tumor cells to an acidic environment on the radiation-induced clonogenic death.

Materials and methods: Rat gliosarcoma cells were used throughout the in vitro study. Cells were exposed to pH 6.6 medium for varying durations of up to 4 days before and after X-irradiation. Cell viability, apoptosis, clonogenic cell death and cell cycle distribution were observed.

Results: Incubation of tumor cells in pH 6.6 medium for 2 or 4 days extended cell cycle, decreased cell viability, and induced apoptotic and clonogenic cell death. The radiation-induced clonogenic death was increased by 2- or 4-day pre-irradiation exposure of tumor cells to pH 6.6 medium, whereas it was reduced by 4-day post-irradiation exposure to an acidic medium.

Conclusion: Prolonged exposure to an acidic environment enhanced the sensitivity of tumor cells to subsequent X-irradiation. However, the radiosensitization by pre-irradiation exposure was almost completely nullified by prolonged post-irradiation exposure to an acidic environment.     

T7 RNA聚合酶催化的荧光扩增技术检测结直肠癌循环肿瘤细胞hTERT与临床病理的关系

目的探讨T7 RNA聚合酶催化的荧光扩增技术(Cellular FACTT)检测人循环肿瘤细胞中hTERT表达与临床病理的关系。方法Cellular FACTT法检测76例结直肠癌患者循环肿瘤细胞,与术后患者临床病理特征进行统计学分析。结果 76例结直肠癌患者CellularFACTT方法检测外周血循环肿瘤细胞阳性检出率与TNM分期、M分期相关及与肿瘤分化程度具有相关性。结论 T7 RNA聚合酶催化的荧光扩增技术具有很高的敏感性,有可能作为一种新的检测方法用于临床的诊断,对判断结直肠癌预后、指导治疗具有一定临床意义。     

间充质干细胞联合骨髓细胞输注诱导胰岛移植免疫耐受的研究

目的观察间充质干细胞(MSC)联合骨髓细胞(BMC)输注对同种异体小鼠胰岛移植嵌合状态及胰岛移植物存活时间的影响。方法C57BL/6小鼠和BALB/C小鼠分别作为供、受体。应用链脲佐菌素制备BALB/C小鼠糖尿病模型,将分离纯化的C57BL/6小鼠胰岛移植到上述糖尿病模型小鼠的肾包囊下,用抗CD154单抗进行受体预处理。将接受胰岛移植的25只BALB/C受体鼠随机分为A组(单纯胰岛移植);B组(供体MSC悬液0.5ml输注);C组(供体BMC悬液0.5ml输注);D组(供体BMC和MSC各0.5ml输注);E组(供体BMC和第三品系的KM小鼠MSC各0.5ml输注),每组5只,所有细胞在胰岛移植后经尾静脉输注。比较以上各组供体细胞嵌合率(DC)和胰岛移植物存活时间的差异。结果在胰岛移植后第30天,MSC联合BMC输注的D、E两组与单纯BMC输注的C组比较,其DC显著升高(P<0.01);胰岛存活时间亦显著延长[(77.0±7.7d)和(61.0±2.2d)vs(53.0±16.4d)(P<0.01)]。胰岛移植后第60天,D组与E组比较,DC维持在更高水平,且胰岛移植物存活时间更长(P<0.05)。结论MSC联合BMC输注比单纯BMC输注能够维持更长时间的混合嵌合状态,并延长胰岛移植物存活时间;供体来源的MSC输注比非供体来源的MSC输注更有效。     

PKB转染SHG44细胞辐射抗性机制的初步研究

目的 探讨通过抑制蛋白激酶B（PKB、AKT）活性增加辐射敏感性，从而证实PKB活性是诱导SHG44细胞辐射抗性的机制之一。方法采用电穿孔法将PKB基因[pCMV5．HA-m／p-PKBa（PKB）、pCMV5-HA-PKBα-DD（T308D／S473D）（PKBD）]转染SHG44细胞；MTT法检测对照、PKB转染组及照射后各组细胞增殖率，激光共聚焦显微镜扫描技术观察对照、对照＋照射、PKB转染＋照射、PKBD转染＋照射组细胞凋亡及微细结构的变化；分析PKB转染的SHG44细胞增殖以及诱导凋亡的相关因素。结果含有外源性PKB的质粒成功转染了SHG44细胞并表达PKBmRNA，而对照组未见表达；转染后的SHG44细胞增殖率与对照组比较差异具有统计学意义（P〈0．05）；60Coγ），线照射能诱导SHG44细胞凋亡，以细胞核形态变化为特征；PKB＋照射组SHG44细胞形态完整，偶见凋亡细胞；而PKBD＋照射与对照＋照射组相比凋亡更显著。结论PKB转染SHG44细胞能抵抗辐射诱导的细胞凋亡，证实PKB活性与SHG44细胞辐射抗性存在一定的相关性。     

电镜形态和DNA链断裂研究153Sm内照射诱发骨肉瘤细胞凋亡

目的对１５３Ｓｍ－ＥＤＴＭＰ内照射诱发骨肉瘤细胞凋亡和ＤＮＡ链断裂程度进行了研究。方法观察１５３Ｓｍ－ＥＤＴＭＰ内照射不同时间，诱发骨肉瘤细胞凋亡的电镜形态及ＤＮＡ链断裂程度。结果研究发现，在１５３Ｓｍ－ＥＤＴＭＰ内照射作用下，可呈现核断裂，核染质边聚，以及膜包裹着的凋亡小体形成的骨肉瘤细胞凋亡的形态特征。并且观察到随着１５３Ｓｍ－ＥＤＴＭＰ内照射作用时间的延长，则骨肉瘤细胞的ＤＮＡ链断裂程度亦随之增升。结论１５３Ｓｍ－ＥＤＴＭＰ内照射治疗时，可诱发骨肉瘤细胞凋亡发生，且凋亡的程度与１５３Ｓｍ－ＥＤＴＭＰ内照射作用时间相关     

LPS诱导肺微血管内皮细胞ICAM-1的表达及核调控机理的实验研究

目的：研究细胞脂多糖（LPS）诱导的肺微血管内皮细胞（PMVEC）ICAM－1的表达及调控机制，方法：100ng.ml^-1LPS刺激PMVEC0h,2h,4h,6h,8h或10ng.ml^-1，50ng.ml^-1,100ng.ml^-1LPS刺激6h，免疫细胞化学检测PMVECICAM－1的表达，凝胶电泳迁移率变化分析检测NF－κB的活化，并通过加入活化阻断剂PDTC观察对PMVEC ICAM－1表达的影响。结果：PMVECICAM－1的表达与LPS的刺激呈时相－剂量依赖方式，LPS的刺激迅速活化NF－κB，60min达到高峰，后逐渐下降，PDTC能显著降低ICAM－1的表达（P＜0．01），结论：LPS刺激诱导NF－κB的活化，启动ICAM－1的合成表达。