Anti-apoptotic Bcl-2 proteins: structure,function and relevance for radiation biology

PURPOSE: Bcl-2 family members mediate anti-apoptotic signals in a wide variety of human cell systems. Despite its proven antiapoptotic function, several results indicate that overexpression of Bcl-2 is not clearly associated with increased radiation resistance in vitro or in vivo. The reasons for this obvious contradiction are not understood. MATERIALS AND METHODS: Current data on the function of Bcl-2 as an anti-apoptotic protein, its role for the modulation of radiation sensitivity in vitro and its value as prognostic marker in vivo are reviewed. RESULTS: Bcl-2 and related proteins are currently perceived to be the most important anti-apoptotic proteins. Their function is related to their ability to interfere with mitochondrial apoptosis pathways. Contradictory data have been published on the relevance of Bcl-2 and related family members for in vitro and in vivo tumour response. The value of Bcl-2 as a prognostic marker thus remains unclear. CONCLUSIONS: Although Bcl-2-related proteins are currently the most relevant anti-apoptotic modulators, their relevance for radiation responses in vivo or in vitro remain undefined. Furthermore, their determination in a routine clinical setting does not appear to be justified.     

Anti-apoptotic Bcl-2 proteins: structure,function and relevance for radiation biology

Purpose : Bcl-2 family members mediate anti-apoptotic signals in a wide variety of human cell systems. Despite its proven antiapoptotic function, several results indicate that overexpression of Bcl-2 is not clearly associated with increased radiation resistance in vitro or in vivo. The reasons for this obvious contradiction are not understood. Materials and methods : Current data on the function of Bcl-2 as an anti-apoptotic protein, its role for the modulation of radiation sensitivity in vitro and its value as prognostic marker in vivo are reviewed. Results : Bcl-2 and related proteins are currently perceived to be the most important anti-apoptotic proteins. Their function is related to their ability to interfere with mitochondrial apoptosis pathways. Contradictory data have been published on the relevance of Bcl-2 and related family members for in vitro and in vivo tumour response. The value of Bcl-2 as a prognostic marker thus remains unclear. Conclusions : Although Bcl-2-related proteins are currently the most relevant anti-apoptotic modulators, their relevance for radiation responses in vivo or in vitro remain undefined. Furthermore, their determination in a routine clinical setting does not appear to be justified.     

Effect of radiation on Ewing tumour subpopulations characterized on a single-cell level: intracellular cytokine,immunophenotypic, DNA and apoptotic profile

PURPOSE: Adhesion molecules, cytokines and their corresponding cell-surface receptors are involved in intercellular signalling pathways, radioresistance and metastasis-mediating mechanisms of malignant cells. The aim was the characterization of changes in the marker profile of Ewing tumour cell subpopulations under the influence of radiation. MATERIALS AND METHODS: Three Ewing tumours were characterized in vitro and in vivo in a xenograft model before and after radiation by five-parameter flow cytometry. Antibodies directed against cell surface and intracellular antigens, apoptosis-associated markers and the DNA dye 7-aminoactinomycin D were used. RESULTS: Tumour cell subpopulations were identified by expression of adhesion molecules and cytokine receptors, intracellular cytokines, apoptotic markers and DNA content. Heterogeneous changes of flow cytometric profile were identified on tumour cell subpopulations after radiation. CONCLUSIONS: The changed profile of tumour cells under radiation might be associated with biological changes of tumour subpopulations in view of radioresistance and metastatic potential and might be useful to identify intercellular regulation mechanisms and to define parameters being predictive for a response to therapy.     

Effect of radiation on Ewing tumour subpopulations characterized on a single-cell level: intracellular cytokine,immunophenotypic, DNA and apoptotic profile

Purpose : Adhesion molecules, cytokines and their corresponding cell-surface receptors are involved in intercellular signalling pathways, radioresistance and metastasis-mediating mechanisms of malignant cells. The aim was the characterization of changes in the marker profile of Ewing tumour cell subpopulations under the influence of radiation. Materials and methods : Three Ewing tumours were characterized in vitro and in vivo in a xenograft model before and after radiation by five-parameter flow cytometry. Antibodies directed against cell surface and intracellular antigens, apoptosis-associated markers and the DNA dye 7-aminoactinomycin D were used. Results : Tumour cell subpopulations were identified by expression of adhesion molecules and cytokine receptors, intracellular cytokines, apoptotic markers and DNA content. Heterogeneous changes of flow cytometric profile were identified on tumour cell subpopulations after radiation. Conclusions : The changed profile of tumour cells under radiation might be associated with biological changes of tumour subpopulations in view of radioresistance and metastatic potential and might be useful to identify intercellular regulation mechanisms and to define parameters being predictive for a response to therapy.     

A head immobilization system for radiation simulation, CT, MRI, and PET imaging

An aquaplast mask/marker immobilization system for the routine radiation therapy treatment of head and neck disease is described. The system utilizes a commercially available thermoplastic mesh indexed and mounted to a rigid frame attached to the therapy couch. The apparatus is designed to permit CT, MRI, and PET diagnostic scans of the patient to be performed in the simulation and treatment position utilizing the same mask, thereby facilitating image correlation. Studies employing weekly simulation indicate that patient treatment position movement can be restricted to 3 mm over the course of treatment. This easily constructed system permits rapid mask formation to be performed on the treatment simulator, resulting in an immobilization device comparable to masks produced with vacuum-forming techniques. Details of construction, verification, and central axis CT, MRI, PET markers are offered.     

人慢性放射性皮肤溃疡中端粒酶活性升高

探讨人慢性放射性皮肤溃疡中端粒酶活性状况及其与癌变的可能关系。方法应用非同位素端粒重复序列扩增技术检测２０例人慢性放射性皮肤溃疡，５例正常皮肤，５例癌组织。结果放射性皮肤溃疡端粒酶活性升高阳性率为３０．０％（６／２０）；正常皮肤组织为阴性（０／５）；癌组织阳性率为１００％（５／５），放射性皮肤溃疡的端粒酶活性强度稍弱于癌组织。结论端粒酶活性测定可能成为判定慢性放射性皮肤溃疡预后和治疗效应的标志     

γ-H2AX分析及其在监测电离辐射所致DNA双链断裂中的应用前景

近几年的研究表明,组蛋白H2AX在DNA损伤修复、细胞周期检查点调控、基因组稳定的维持和肿瘤抑制中起着重要作用,而且在放射生物学中具有应用前景。磷酸化的组蛋白H2AX (y-H2AX)对DNA双链断裂快速敏感的反应使其成为DNA双链损伤的标志。y-H2AX分析也将在监测电离辐射尤其是低剂量电离辐射所致的DNA双链损伤中拥有广阔的应用前景。     

Cytogenetic investigation of occupationally irradiated persons a long time after exposure.

Chromosomal analyses were performed in blood lymphocytes of 33 persons previously occupationally exposed to ionizing radiation. An increased frequency of chromosome aberrations, mainly dicentrics, a long time, up to 47 years after exposure, suggests that it is possible to use the method of unstable aberration analysis for assessment of previous radiation exposure. The enhanced yield of dicentrics was observed in persons who may have received irradiations above permitted limits. The aberrations represent a residue from a higher initially induced incidence. They can not be used reliably for retrospective dosimetry but do provide a marker for old exposure.     

透明质酸、层粘连蛋白作为早期放射性肺损伤标志物的实验研究

目的 :探索透明质酸和层粘连蛋白对早期放射性肺损伤的诊断价值以及氟伐他汀对放射性肺损伤的治疗作用。方法 :将SD大鼠随机分为正常对照组 (C组 )、单纯照射组 (R组 )和氟伐他汀防治组 (TG组 )。TG组于照射前一周开始服氟伐他汀2 0mg·kg- 1·d- 1,直至活杀。其他组灌服等容量生理盐水。R组和TG组以直线加速器全胸部照射 ,单次剂量 2 0Gy ,于照射后5、15、3 0、60d以硫喷妥钠 40mg·kg- 1腹腔内注射。麻醉后固定 ,抽取心脏血 3ml ,分离血清。用放射免疫法测透明质酸、层粘连蛋白含量 ,统计分析用重复测量多因素方差分析和t检验。结果 :透明质酸在R组于照射后 60d较C组显著升高 (P <0 .0 1) ,TG组较R组减低 (P <0 .0 5)。层粘连蛋白在R组 3 0、60d较C组升高 (P <0 .0 5) ,TG组在相应时间减低 (P <0 .0 5)。结论 :透明质酸可作为放射性肺炎治疗情况的监测指标 ,层粘连蛋白可以作为预测纤维组织增生的一个早期指标 ;氟伐他汀对放射性肺损伤有一定的防治作用 ,用药后透明质酸、层粘连蛋白增高均受抑制     

Response of human lymphocytes to mitogenic stimuli after irradiation in vitro.

Human lymphocytes were exposed to varying doses of roentgen irradiation in vitro and thereafter tested for reactivity to different polyclonal mitogens and antigens using DNA synthesis as a marker for viability. The dose response profiles obtained indicate that there are two subpopulations of lymphocytes which are responsive to phytohaemagglutinin, poke weed mitogen, concanavalin A and allogeneic cells. One is relatively sensitive to radiation and the other is relatively resistant. However, no "resistant" PPD-tuberculin responsive cell population could be detected. Irradiated lymphocyte populations enriched for T-cells exhibited both a sensitive and a resistant PHA-responsive population, whereas cell populations enriched for B-cells only exhibited a radiation sensitive one.     

Potential of dose reduction after marker placement with full-field digital mammography

OBJECTIVES: The purpose of our study was to assess the potential for radiation dose reduction in digital postinterventional digital mammograms after marker placement. MATERIALS AND METHODS: One hundred consecutive cases of marker placement (hook-wire localization or postbiopsy clip marker placement), with 200 full-field digital baseline mammograms (craniocaudal and mediolateral), were included in this prospective trial. For the postinterventional digital mammograms, the milliampere seconds were reduced either by 50% or by 75%. Dose-reduced images were evaluated for sufficient image quality to verify the position of the marker. RESULTS: In 193 of 200 cases (96.5%), image quality was sufficient to verify the correct position of the marker. One (1%) case with insufficient image quality occurred in the 50% dose-reduction group and 6 (6%) in the 75% dose-reduction group (P = 0.06). CONCLUSION: Our results indicate that under evaluation of each individual case, a dose reduction of 50% to 75% can be recommended in postinterventional digital mammograms.     

Dosimetric perturbation due to scattered rays released by a gold marker used for tumor tracking in external radiotherapy

Image-guided radiation therapy using a gold marker-based tumor tracking technique provides precise patient setup and monitoring. However, the marker consists of high-Z material, and the resulting scattered rays tend to have adverse effects on the dose distribution of radiotherapy. The purpose of this study was to evaluate the dosimetric perturbation due to the use of a gold marker for radiotherapy in the lungs. The relative dose distributions were compared with film measurement, Monte Carlo simulation, and XiO calculation with the multi grid superposition algorithm using two types of virtual lung phantoms, which were composed of tough water phantoms, tough lung phantoms, cork boards, and a 2.0-mm-diameter gold ball. No dose increase and decrease in the vicinity of the gold ball was seen in the XiO calculations, although it was seen in the film measurements and the Monte Carlo simulation. The dose perturbation due to a gold marker cannot be evaluated using XiO calculation with the superposition algorithm when the tumor is near a gold marker (especially within 0.5 cm). To rule out the presence of such dose perturbations due to a gold marker, the distance between the gold marker and the tumor must therefore be greater than 0.5 cm.     

微卫星DNA及其在放射医学领域中的应用前景

微卫星 DNA(MSDNA)是真核生物基因组重复序列中的主要组成部分之一。由于其分布广、多态性高、自身突变率低、易检测等特点 ,脱颖而出 ,成为优秀的遗传标志 ,广泛用于基因定位、基因作图、种群研究、个体识别 ,并与肿瘤、某些遗传疾病密切相关。射线作为一种环境致突变因子 ,可引起遗传改变及肿瘤形成 ,因此 ,MSDNA近年来在放射医学领域也有较为广泛的应用。     

Evaluation of continuous low dose rate versus acute single high dose rate radiation combined with oncolytic viral therapy for prostate cancer

Purpose:?Conditionally Replicative Adenovirus (CRAd) has been previously demonstrated to augment the activity of radiation, resulting in synergy of cell kill. However, previous models combining radiation with CRAd have not focused on the methods of radiation delivery.

Materials and methods:?We model the combination of a novel prostate-specific CRAd, Ad5 PSE/PBN E1A-AR (Ad5: adenovirus 5; PSE: prostate-specific enhancer; PBN: rat probasin promoter; E1A: early region 1A; AR: androgen receptor), with radiation delivered both acutely and continuously, in an effort to better mimic the potential clinical modes of prostate cancer radiotherapy.

Results:?We demonstrate that pre-treatment of cells with acute single high dose rate (HDR) radiation 24 hours prior to viral infection results in significantly enhanced viral replication and virus-mediated cell death. In addition, this combination causes increased level of γ-H2AX (Phosphorylated histone protein H2AX on serine 139), a marker of double-stranded DNA damage and an indirect measure of nuclear fragmentation. In contrast, continuous low dose rate (LDR) radiation immediately following infection of the same CRAd results in no enhancement of viral replication, and only additive effects in virus-mediated cell death.

Conclusions:?These data provide the first direct assessment of the real-time impact of radiation on viral replication and the first comparison of the effect of radiation delivery on the efficacy of CRAd virotherapy. Our data demonstrate substantial differences in CRAd efficacy based on the mode of radiation delivery.     

Upregulated epithelial junction expression represents a novel parameter of the epithelial radiation response to fractionated irradiation in oral mucosa

Purpose

During head and neck cancer treatment, the radiation response of the oral mucosa represents a frequent early side effect. Besides radiation-induced inhibition of proliferation, various other cellular responses occur. The radiation response of adherens and tight junction proteins was so far mostly investigated with large single-dose irradiation protocols, in vivo and in vitro. Therefore, the current study was initiated to investigate the impact of daily fractionated irradiation on the expression of adherens and tight junction proteins in vivo.

Materials and methods

Fractionation with 5?×?3?Gy/week (days 0–4, 7–11) was given to the snouts of mice. Groups of 5 animals per day were euthanized every second day between day 0 (unirradiated controls) and day 14, and their tongues subjected to histological processing. Adherens junction marker (β-catenin and E?cadherin) and tight junction marker (claudin-1 and occludin) expression was analysed in the oral mucosa of unirradiated controls and during two weeks of fractionated irradiation.

Results

Adherens as well as tight junction marker proteins were rapidly and consistently upregulated in both the germinal as well as the functional layer of the oral mucosa. This represents a previously unknown parameter of the epithelial radiation response to clinically relevant fractionation protocols.

Conclusion

Fractionated irradiation significantly enhanced the expression of all proteins investigated. This study revealed a new parameter of the epithelial radiation response to fractionated irradiation.

     

Short-term reproducibility of computed tomography-based lung density measurements in alpha-1 antitrypsin deficiency and smokers with emphysema

PURPOSE: To study the short-term reproducibility of lung density measurements by multi-slice computed tomography (CT) using three different radiation doses and three reconstruction algorithms. MATERIAL AND METHODS: Twenty-five patients with smoker's emphysema and 25 patients with alpha1-antitrypsin deficiency underwent 3 scans at 2-week intervals. Low-dose protocol was applied, and images were reconstructed with bone, detail, and soft algorithms. Total lung volume (TLV), 15th percentile density (PD-15), and relative area at -910 Hounsfield units (RA-910) were obtained from the images using Pulmo-CMS software. Reproducibility of PD-15 and RA-910 and the influence of radiation dose, reconstruction algorithm, and type of emphysema were then analysed. RESULTS: The overall coefficient of variation of volume adjusted PD-15 for all combinations of radiation dose and reconstruction algorithm was 3.7%. The overall standard deviation of volume-adjusted RA-910 was 1.7% (corresponding to a coefficient of variation of 6.8%). Radiation dose, reconstruction algorithm, and type of emphysema had no significant influence on the reproducibility of PD-15 and RA-910. However, bone algorithm and very low radiation dose result in overestimation of the extent of emphysema. CONCLUSION: Lung density measurement by CT is a sensitive marker for quantitating both subtypes of emphysema. A CT-protocol with radiation dose down to 16 mAs and soft or detail reconstruction algorithm is recommended.     

Stable radioresistance in ataxia-telangiectasia cells containing DNA from normal human cells

SV40-transformed ataxia-telangiectasia (AT) cells were transfected with a cosmid that contains a normal human DNA library and a selectable marker, the neo gene, which endows successfully transformed mammalian cells with resistance to the antibiotic G418. After a three-part selection protocol for G418 resistance and radioresistance, a cell line stably resistant to ionizing radiation was recovered. Cells from this line were irradiated with 50 Gy of X-rays and fused with non-transfected AT cells. Among the G418-resistant colonies recovered was one that was stably resistant to radiation. Resistance to ionizing radiation of both the primary transfectant line and its fusion derivative was intermediate between that of AT cells and normal cells, as assayed by colony-forming ability and measurement of radiation-induced G2 chromatid aberrations; both cell lines retained AT-like radioresistant DNA synthesis. These results suggest that, because radioresistance in the transfected cells was not as great as that in normal human cells, the two hallmarks of AT, radiosensitivity and radioresistant DNA synthesis, may still be the result of a single defective AT gene.     

Survey and analysis of radiation safety management systems at medical institutions--second report: radiation measurement, calibration of radiation survey meters, and periodic check of installations, equipment, and protection instruments

We carried out a questionnaire survey to determine the actual situation of radiation safety management measures in all medical institutions in Japan that had nuclear medicine facilities. The questionnaire consisted of questions concerning the evaluation of shielding capacity; radiation measurement; periodic checks of installations, equipment, and protection instruments; and the calibration of radiation survey meters. The analysis was undertaken according to region, type of establishment, and number of beds. The overall response rate was 60 percent. For the evaluation of shielding capacity, the outsourcing rate was 53 percent of the total. For the radiation measurements of "leakage radiation dose and radioactive contamination" and "contamination of radioactive substances in the air," the outsourcing rates were 28 percent and 35 percent of the total, respectively (p<0.001, according to region and establishment). For the periodic check of radiation protection instruments, the implementation rate was 98 percent, and the outsourcing rate was 32 percent for radiation survey meters and 47 percent for lead aprons. The non-implemented rate for calibration of radiation survey meters was 25 percent of the total (p<0.001, according to region and establishment). The outsourcing rate for calibration of radiation survey meters accounted for 87 percent of the total, and of these medical institutions, 72 percent undertook annual calibration. The implementation rate for patient exposure measurement was 20 percent of the total (p<0.001, according to number of beds), and of these medical institutions 46 percent recorded measurement outcome.     

Stable chromosomal aberrations in haemopoietic stem cells in the blood of radiation accident victims

Purpose : The detection of long-term persistent chromosome aberrations in circulating haemopoietic stem cells after accidental radiation exposure. Materialand methods : Peripheral blood samples fromhighly exposed persons were collected 7-25 years after the radiation accidents in Moscow (1971), Kazan (1975) and Chernobyl (1996). Haemopoietic blood stem cells were analysed when investigating individual colonies derived from haemopoietic progenitor cells: burst-forming units-erythroid (BFU-E), granulocytemacrophage-colony-forming cells (GM-CFC) and multipotent granulocyte-erythrocyte-macrophage-megakaryocyte-colonyforming cells (GEMM-CFC). Colony formation was obtained in methylcellulose cultures. Chromosome preparations in single colonies were performed using a microtechnique. Results : Nine patients were investigated at 1 to 4 follow-up time points after radiation exposure. Three hundred and thirty-four single colonies were analyzed resulting in 1375 mitoses. It was found that colonies showed chromosome aberrations (ChA) up to 25 years after radiation exposure by classical cytogenetics and by fluorescence in situ hybridization (FISH). Stable aberrations were detected in 21% of colonies. They were clonal in 19% of colonies, i.e. the same abnormality was found in all cells derived from a single colony. In 2% of colonies ChA were stable but non-clonal; unstable ChA were not observed. Conclusions : The results indicate that blood-derived haemopoietic stem cells may serve as a biological indicator to detect radiation-induced ChA. Since they are considered to be in dynamic and functional exchange with stem cells in the medullary sites of blood cell formation such as bone marrow, the use of blood stem cells as a marker of radiation effects should be explored to assess the repair status of the stem cell pool as such.     

Stable chromosomal aberrations in haemopoietic stem cells in the blood of radiation accident victims.

PURPOSE: The detection of long-term persistent chromosome aberrations in circulating haemopoietic stem cells after accidental radiation exposure. MATERIAL AND METHODS: Peripheral blood samples from highly exposed persons were collected 7-25 years after the radiation accidents in Moscow (1971), Kazan (1975) and Chernobyl (1996). Haemopoietic blood stem cells were analysed when investigating individual colonies derived from haemopoietic progenitor cells: burst-forming units-erythroid (BFU-E), granulocyte-macrophage-colony-forming cells (GM-CFC) and multipotent granulocyte-erythrocyte-macrophage- megakaryocyte-colony-forming cells (GEMM-CFC). Colony formation was obtained in methylcellulose cultures. Chromosome preparations in single colonies were performed using a microtechnique. RESULTS: Nine patients were investigated at 1 to 4 follow-up time points after radiation exposure. Three hundred and thirty-four single colonies were analyzed resulting in 1375 mitoses. It was found that colonies showed chromosome aberrations (ChA) up to 25 years after radiation exposure by classical cytogenetics and by fluorescence in situ hybridization (FISH). Stable aberrations were detected in 21% of colonies. They were clonal in 19% of colonies, i.e. the same abnormality was found in all cells derived from a single colony. In 2% of colonies ChA were stable but non-clonal; unstable ChA were not observed. CONCLUSIONS: The results indicate that blood-derived haemopoietic stem cells may serve as a biological indicator to detect radiation-induced ChA. Since they are considered to be in dynamic and functional exchange with stem cells in the medullary sites of blood cell formation such as bone marrow, the use of blood stem cells as a marker of radiation effects should be explored to assess the repair status of the stem cell pool as such.