Cell inactivation by combined low dose-rate irradiation and intermittent hypoxia

Abstract

Purpose: To investigate in detail the earlier observed combined effect of low dose-rate β-irradiation delivered at a dose-rate of 15 mGy/h and continued intermittent hypoxia that leads to extensive cell death after approximately 3–6 weeks.

Material and methods: Continuous low dose-rate β-irradiation at a dose rate of 15, 1.5 or 0.6 mGy/h was given by incorporation of [³H]-labelled valine into cellular protein. The cells were cultivated in an atmosphere with 4% O₂ using an INVIVO₂ hypoxia glove box. Clonogenic capacity, cell-cycle distribution and cellular respiration were monitored throughout the experiments.

Results: After 3–6 weeks most cells died in response to the combined treatment, giving a surviving fraction of only 1–2%. However, on continued cultivation a few cells survived and restarted proliferation as the cellular oxygen supply increased with the reduced cell number. Irradiating the T-47D cells grown in an atmosphere with 4% O₂ at dose-rates 10 and 25 times lower than 15 mGy/h did not have a pronounced effect on the clonogenic capacity with surviving fractions of 60–80%.

Conclusions: Treatment of T-47D cells with low dose-rate β-irradiation leads to a specific effect on intermittent hypoxic cells, inactivating more than 98% of the cells in the population. Given improved oxygen conditions, the few surviving cells can restart their proliferation.     

Risk of solid cancer in low dose-rate radiation epidemiological studies and the dose-rate effectiveness factor

Abstract

Purpose: Estimated radiation risks used for radiation protection purposes have been based primarily on the Life Span Study (LSS) of atomic bomb survivors who received brief exposures at high dose rates, many with high doses. Information is needed regarding radiation risks from low dose-rate (LDR) exposures to low linear-energy-transfer (low-LET) radiation. We conducted a meta-analysis of LDR epidemiologic studies that provide dose-response estimates of total solid cancer risk in adulthood in comparison to corresponding LSS risks, in order to estimate a dose rate effectiveness factor (DREF).

Materials and methods: We identified 22 LDR studies with dose-response risk estimates for solid cancer after minimizing information overlap. For each study, a parallel risk estimate was derived from the LSS risk model using matching values for sex, mean ages at first exposure and attained age, targeted cancer types, and accounting for type of dosimetric assessment. For each LDR study, a ratio of the excess relative risk per Gy (ERR Gy^?1) to the matching LSS ERR risk estimate (LDR/LSS) was calculated, and a meta-analysis of the risk ratios was conducted. The reciprocal of the resultant risk ratio provided an estimate of the DREF.

Results: The meta-analysis showed a LDR/LSS risk ratio of 0.36 (95% confidence interval [CI] 0.14, 0.57) for the 19 studies of solid cancer mortality and 0.33 (95% CI 0.13, 0.54) when three cohorts with only incidence data also were added, implying a DREF with values around 3, but statistically compatible with 2. However, the analyses were highly dominated by the Mayak worker study. When the Mayak study was excluded the LDR/LSS risk ratios increased: 1.12 (95% CI 0.40, 1.84) for mortality and 0.54 (95% CI 0.09, 0.99) for mortality?+?incidence, implying a lower DREF in the range of 1–2. Meta-analyses that included only cohorts in which the mean dose was <100 mGy yielded a risk ratio of 1.06 (95% CI 0.30, 1.83) for solid cancer mortality and 0.58 (95% CI 0.10, 1.06) for mortality?+?incidence data.

Conclusions: The interpretation of a best estimate for a value of the DREF depends on the appropriateness of including the Mayak study. This study indicates a range of uncertainty in the value of DREF between 1 and about 2 after protracted radiation exposure. The LDR data provide direct evidence regarding risk from exposures at low dose rates as an important complement to the LSS risk estimates used for radiation protection purposes.     

低剂量134Cs内照射对中枢免疫器官免疫反应的兴奋效应研究

作者探讨了机体受低剂量裂变产物１３４Ｃｓ内照射时的体内滞留对中枢免疫器官骨髓和胸腺免疫细胞的刺激增生作用．１３４Ｃｓ的体内滞留过程包括快、慢两个不同的滞留半减期，其中快组份的Ｔ１＝０．０７天，慢组份的Ｔ２＝１６．３８天．实验结果表明：当机体摄入低剂量１３４Ｃｓ０．１８５和０．７４ｋＢｑ·ｇ－１时，即此时的全身累积吸收剂量为０．９１ｃＧｙ和４．５６ｃＧｙ作用下，发现骨髓细胞和胸腺细胞的３Ｈ－ＴｄＲ掺入率呈显著增升，表明其ＤＮＡ合成能力的增高，呈现出１３４Ｃｓ内照射对中枢免疫器官骨髓和胸腺免疫反应增强的兴奋效应．     

低剂量照射对LAK细胞体外杀伤肿瘤靶细胞的影响

作者采用＾Ｈ－ＴｄＲ释放实验，观察了低剂量γ射线照射的ＬＡＫ细胞体外杀伤肿瘤靶细胞的影响。来自健康献血员的外周血淋巴细胞，用重组白介素２培养９６小时获取ＬＡＫ效应细胞，在细胞培养的不同时期给予培养中的细胞一次不同剂量的γ射线照射。     

Enhanced transplantability of a cell line from a murine ovary granulosa cell tumour in syngeneic B6C3F1 mice continuously irradiated with low dose-rate gamma-rays

Purpose:?To understand the mechanisms of life-shortening due to early neoplastic death caused by chronic low dose-rate (LDR; 20 mGy/22 h/day) radiation which accumulates to a high dose (HD; 8 Gy) (LDR/HD) as reported previously.

Materials and methods:?Female B6C3F₁ mice were continuously exposed to LDR/HD gamma-rays under specific-pathogen-free (SPF) conditions for 400 days. OV3121 cells, which were derived from an ovarian granulosa cell tumour that arose in irradiated B6C3F₁ mice, were inoculated into LDR/HD irradiated and age-matched non-irradiated control mice. The transplantability of tumour cells as well as T cell subsets and the proliferative activities of T cells were compared between irradiated and non-irradiated mice.

Results:?We found that tumour formation of subcutaneously inoculated tumour cells occurred earlier in irradiated mice than in non-irradiated mice. Proliferative activity of draining lymph node lymphocytes against transplanted tumour cells as well as allogeneic mixed lymphocyte reactions were significantly reduced in irradiated mice compared to non-irradiated mice.

Conclusions:?These results suggest that decreased tumour-specific immune response due to LDR/HD irradiation may enhance tumorigenesis resulting in life-shortening of mice after chronic LDR/HD irradiation.     

Increase in efficacy of cancer radiotherapy by combination with whole-body low dose irradiation

Purpose:Design of cancer radiotherapy protocol to reduce radiation dose and increase treatment efficacy in Lewis lung cancer (LLC) model.

Methods: C57BL/6J mice subcutaneously implanted with LLC were treated by conventional radiotherapy (2Gy × 6) combined with LDWBI (low dose whole-body irradiation; the second, third, fifth and sixth local doses of 2Gy each substituted by LDWBI with 0.075Gy) and/or gene therapy (intratumor injection of pEgr-IL-18-B7.1 plasmid 24 h before the first and fourth local doses). Immunologic mechanisms were explored.

Results: Cancer control was most significantly improved in the group receiving local radiotherapy combined with LDWBI and gene therapy as shown by prolongation of mean survival time by 60.4%, reduction in average tumor weight by 70.8%, decrease in pulmonary metastasis by 66.9% and decrease in intratumor angiogenesis by 64.8% as compared to local radiotherapy alone (p < 0.05). These changes in tumor growth and progression were accompanied with up-regulation of host immunity manifested by stimulated NK (natural killer) and CTL (cytotoxic T lymphocyte) activity, IFN (interferon)-gamma and TNF (tumor necrosis factor)-alpha secretion, PKC (protein kinase C)-theta activation and LAMP (lysosomal associated membrane protein)-1 expression.

Conclusion: Combination of conventional radiotherapy with LDWBI and gene transfer could reduce total radiation dose by 2/3 and at the same time improve treatment efficacy of cancer accompanied with up-regulated host anticancer immunity.     

Experimental studies on the biological effects of chronic low dose-rate radiation exposure in mice: overview of the studies at the Institute for Environmental Sciences

This review summarizes the results of experiments conducted in the Institute for Environmental Sciences for the past 21 years, focusing on the biological effects of long-term low dose-rate radiation exposure on mice. Mice were chronically exposed to gamma rays at dose-rates of 0.05, 1 or 20?mGy/day for 400 days to total doses of 20, 400 or 8000?mGy, respectively. The dose rate 0.05?mGy/day is comparable to the dose limit for radiation workers. The parameters examined were lifespan, neoplasm incidence, antineoplasm immunity, body weight, chromosome aberration(s), gene mutation(s), alterations in mRNA and protein levels and trans-generational effects. At 20?mGy/day, all biological endpoints were significantly altered except neoplasm incidence in the offspring of exposed males. Slight but statistically significant changes in lifespan, neoplasm incidences, chromosome abnormalities and gene expressions were observed at 1?mGy/day. Except for transient alterations in the mRNA levels of some genes and increased liver neoplasm incidence attributed to radiation exposure, the remaining biological endpoints were not influenced after exposure to 0.05?mGy/day. Results suggest that chronic low dose-rate exposure may induce small biological effects.     

Transcriptomic profiling suggests a role for IGFBP5 in premature senescence of endothelial cells after chronic low dose rate irradiation

Abstract

Purpose: Ionizing radiation has been recognized to increase the risk of cardiovascular diseases (CVD). However, there is no consensus concerning the dose-risk relationship for low radiation doses and a mechanistic understanding of low dose effects is needed.

Material and methods: Previously, human umbilical vein endothelial cells (HUVEC) were exposed to chronic low dose rate radiation (1.4 and 4.1 mGy/h) during one, three and six weeks which resulted in premature senescence in cells exposed to 4.1 mGy/h. To gain more insight into the underlying signaling pathways, we analyzed gene expression changes in these cells using microarray technology. The obtained data were analyzed in a dual approach, combining single gene expression analysis and Gene Set Enrichment Analysis.

Results: An early stress response was observed after one week of exposure to 4.1 mGy/h which was replaced by a more inflammation-related expression profile after three weeks and onwards. This early stress response may trigger the radiation-induced premature senescence previously observed in HUVEC irradiated with 4.1 mGy/h. A dedicated analysis pointed to the involvement of insulin-like growth factor binding protein 5 (IGFBP5) signaling in radiation-induced premature senescence.

Conclusion: Our findings motivate further research on the shape of the dose-response and the dose rate effect for radiation- induced vascular senescence.     

低剂量CT扫描在颅脑病变复查中的应用价值

目的 探讨低剂量CT扫描在颅脑病变复查中的应用价值.方法 随机选取本院首次颅脑CT检查均有明确异常,2年内CT复查的246例颅脑疾病患者,对照组用200 mAs,低剂量组逐次降低mAs分别为160 mAs、120 mAs、100 mAs,其他条件固定,以优、良、尚好、不合格4个等级评价图像质量.结果 246低剂量扫描患者图像244例达到诊断要求,100 mAs有2例不合格图像系枕大粗隆过大所致后颅窝伪影,加大mAs伪影消失.对照组120 kVp、200 mAs的CTDIvol 25.5 mGy、DLP 446.6 mGy/cm,最低剂量组120 kVp、100 mAs组的CTDIvol 12.9 mGy、DLP 225.8 mGy/cm,其辐射剂量较对照组降低了50％.结论 明确颅脑疾病的患者CT复查时,采用100 mAs扫描,图像质量不影响诊断,辐射剂量明显降低,具有重要的防护意义.     

低剂量辐射增强小鼠肿瘤基因-放射治疗效应的免疫学机制研究

目的 探讨低剂量辐射全身照射对小鼠Lewis肺癌移植肿瘤基因-放疗方案中的免疫增强作用机制。方法 小鼠右后肢皮下接种Lewis肺癌细胞建立荷瘤模型,基因-放疗组中小鼠肿瘤局部注射由多聚乙烯亚胺包裹的pEgr-IL18-B7.1重组质粒,分别接受由2 Gy 局部照射和0.075 Gy 全身照射组合的不同治疗方案,通过³H-TdR标记方法检测小鼠CTL和NK细胞毒活性,ELISA方法检测TNF-α和IFN-γ分泌活性,观察各治疗组对荷瘤小鼠抗肿瘤免疫的作用。结果 在pEgr-IL18-B7.1基因治疗方案中,单次大剂量辐射局部照射后加多次低剂量全身照射与常规多次大剂量辐射局部照射相比,小鼠CTL和NK细胞毒活性显著增强,TNF-α和IFN-γ分泌活性有不同程度的增高。 结论 低剂量辐射可以通过促进CTL和NK细胞毒效应,上调TNF-α和IFN-γ细胞因子表达,从而增强机体抗肿瘤免疫功能,提高肿瘤基因-放疗的抑瘤效果。     

Lack of inverse dose-rate effect and binding of the retinoblastoma gene product in the nucleus of human cancer T-47D cells arrested in G2 by ionizing radiation

PURPOSE: To investigate the radiosensitivity of human breast cancer cells, T-47D, irradiated with low dose-rates and to study activation of the retinoblastoma gene product in the G1 and G2 phases during irradiation. MATERIALS AND METHODS: Cells were irradiated with (60)Co gamma-rays with dose-rates of 0.37 and 0.94 Gy h(-1). Cell survival was measured as the ability of cells to form colonies. Cells were extracted, fixed and stained for simultaneous measurements of nuclear-bound pRB content and DNA content. Cell nuclei were stained with monoclonal antibody PMG3-245 and Hoechst 33258 was used for additional staining of DNA. Two-parametric flow cytometry measurements of pRB and DNA content were performed using a FACSTAR(PLUS) flow cytometer. RESULTS: It was observed that irradiated cells were arrested in G2. No increase in radiation sensitivity was observed when the cells accumulated in G2. Irradiation of cells at both 0.37 and 0.94 Gy h(-1) resulted in exponential dose-survival curves with nearly equal alpha values, i.e. the same radiosensitivity. However, the retinoblastoma gene product was bound in the nucleus, i.e. hypophosphorylated, in about 15% of the cells arrested in G2. CONCLUSIONS: T47-D cells accumulate in G2 during low dose irradiation, but no inverse dose-rate effect, i.e. a more efficient inactivation of cells at lower than at higher dose-rates, was observed. A population of arrested G2 cells has pRB protein bound in the nucleus, and pRB therefore could play a role in protecting cells against radiation-induced cell death in G2.     

能谱 CT 冠状动脉成像中双低技术的应用研究

目的：探讨能谱 CT 低辐射剂量结合低浓度对比剂在冠状动脉血管成像中的应用。方法60例疑诊冠心病患者随机分为 A、B 2组,每组30例。A 组使用350 mg I/mL 对比剂、行常规 CT 扫描,B 组使用300 mg I/mL 对比剂、行宝石能谱低剂量 CT扫描。均采用前瞻性心电门控扫描模式。扫描后 A 组常规重建40%ASiR 序列,B 组重建单能量65 keV、40%ASiR 序列轴面图像,传入 AW4.6工作站重建分析。由2名有经验的医师进行双盲法主观评分;测量主动脉窦部(AS)、左主干(LMA)、左前降支近端(LAD-p)、左回旋支近端(LCX-p)、右冠状动脉近端(RCA-p)CT 值,AS 的噪声(SD)、心包内脂肪 CT 值及 SD,计算信噪比(SNR)、对比噪声比(CNR)。记录 CTDI、DLP,计算有效辐射剂量(ED)。记录碘摄入量。采用两独立样本 t 检验比较2组患者的ED、碘摄入量、平均 CT 值、SD、SNR、CNR。结果2组间图像质量主观评分差异和冠状动脉测量段 CT 值差异均无统计学意义。B 组的 ED 较 A 组降低约29%,差异有统计学意义。碘摄入量 B 组较 A 组减少了约16%。结论冠状动脉 CT 血管成像时,应用能谱低辐射剂量扫描,重建最佳单能量图像,能有效降低辐射剂量和碘摄入量,可获得与常规扫描相当的图像质量。     

低剂量X射线照射对脐带间充质干细胞增殖及成脂成骨分化的影响

目的 探讨低剂量照射对人脐带间充质干细胞(hucMSCs)增殖及成脂、成骨分化的影响.方法 采用组织块贴壁法从人脐带沃顿胶样组织中分离出hucMSCs,并采用流式细胞术检测表面特异性标记.随机分为未予照射的对照组,以及50、100和200 mGy照射组.采用MTT法检测hucMSC在不同照射剂量和不同时间(1～7 d)的增殖情况.取第3代细胞,随机分为照射组(给予200 mGy照射)和对照组(不予照射),在体外诱导其向脂肪、成骨细胞分化,并通过油红O染色、检测碱性磷酸酶(ALP)活性,用RT-PCR检测成骨细胞核结合因子α1的mRNA表达,比较照射组与对照组细胞成脂、成骨分化的不同.结果 9～12 d开始有成纤维细胞从组织块游出贴壁,2周左右达到80%.低剂量照射后2、3、4、5和6 d,不同照射剂量组的细胞增殖均高于对照组(F=159.17、448.81、265.15、183.93、181.83,均P＜0.01),其中以100 mGy组促进细胞增殖作用最明显.照射组成脂诱导2 d后细胞内即有脂滴出现,且第21天成脂率明显高于对照组(t=28.25,P＜0.01).成骨诱导后,照射组ALP活性明显高于对照组(t=16.87,P＜0.01),且成骨细胞核结合因子α1的mRNA水平明显增高(t=14.16,P＜0.01).结论 低剂量照射可以促进hucMSC增殖,并加速其向成脂、成骨细胞分化.

Abstract：

Objective To observe the effects of low dose irradiation (LDR) on proliferation,adipogenesis and osteogenic potential of human umbilical cord mesenchymal stem cells (hucMSCs).Methods hucMSCs were isolated from Wharton's jelly tissue of human umbilical cord by modified tissuepiece inoculation,and flow cytometry was used to detect the expression of specific marker in the hucMSCs.The hucMSCs were randomly divided into two groups:irradiation group undergoing irradiation with the doses 50,100,or 200 mGy respectively,and control group without irradiation.MTT method was applied to evaluate the proliferation of the hucMSCs at different time points with various doses irradiation.The third passage hucMSCs were randomly divided into two groups:irradiation group undergoing low dose irradiation of 200 mGy,and control group without irradiation,and then underwent induction by adipocytic and oesteocytic differentiation induction fluids respectively so as to differentiate into adipocytes and osteoblasts.Oil red O staining was used to detect the activity of alkaline phophatase (ALP),and RT-PCR was used to detect the mRNA expression of core binding factor alpha 1 in human osteoblast.Results After 9-12days,fibroblasts began to swim out of the tissue piece with a confluence rate of 80% 2 weeks later.Within 7 days the absorption values of the hucMSCs undergoing different irradiation doses 2,3,4,5,and 6 days later were all significantly higher than those of the control group(F = 159.17,448.81,265.15,183.93,and 181.83 ,all P <0.01),with the proliferation rates of the 100 mGy subgroup being the highest.After being induced liquid,vacuoles were observed in the irradiated group 2 days later.21 days later,the adipogenic rates of irradiated group was significantly higher than that of the control group (t = 28.25,P <0.01).The ALP activity increased in the irradiated group compared with control group (t=16.87,P <0.01) .The expression level of Cbf-α1 mRNA was up-regulated obviously (t = 14.16,P＜0.01).Conclusions LDR promotes the proliferation of hucMSCs,and accelerates the hucMSCs' differentiation into adipocytes and osteoblasts.     

双低条件下结合最适迭代权重在冠状动脉3D打印技术中应用

目的比较不同权重自适应统计迭代重建(ASIR)技术在低浓度对比剂及低辐射剂量条件下行冠状动脉3D打印的可行性。方法选择2016年3—12月沈阳军区总医院收治的疑诊为冠状动脉心脏病并行冠状动脉CT成像(CCTA)检查的患者20例为研究对象。体质量指数(BMI)20~25 kg/m2,在双低条件下(100 k Vp及270 mg I/ml碘克沙醇对比剂)行前瞻性心电门控技术CCTA扫描,扫描完成后对图像进行滤波反投影法(FBP)及不同权重ASIR重建(20%、40%、60%、80%、100%),并将数据传至3D打印机,行冠状动脉3D建模打印,对3D打印产物进行主客观评价。结果相对于FBP重建算法,20%、40%、60%、80%、100%ASIR图像噪声分别降低9%、21%、30%、45%、52%(P<0.05),信号噪声比(SNR)、对比噪声比(CNR)分别提高约6%、17%、38%、56%、72%及12%、22%、42%、56%、66%(P<0.05)。不同权重ASIR重建图像CT值比较,差异无统计学意义(P>0.05)。行FBP,20%、40%、60%、80%、100%ASIR的3D打印产物主观评分分别为1.6、2.0、4.0、4.1、2.1、1.3分,组间比较,差异有统计学意义(P<0.05)。权重设置在40%、60%ASIR的3D打印产物质量具有最高主观评分,打印冠状动脉的质量最好。结论在双低条件下及ASIR重建技术行冠脉3D打印,相对于FBP重建算法,不同权重ASIR图像在40%、60%时,3D打印产物的质量具有最高主观评分,图像质量最好,同时可大幅度降低患者所受辐射剂量。     

The role of dose rate in radiation cancer risk: evaluating the effect of dose rate at the molecular,cellular and tissue levels using key events in critical pathways following exposure to low LET radiation

Purpose: This review evaluates the role of dose rate on cell and molecular responses. It focuses on the influence of dose rate on key events in critical pathways in the development of cancer. This approach is similar to that used by the U.S. EPA and others to evaluate risk from chemicals. It provides a mechanistic method to account for the influence of the dose rate from low-LET radiation, especially in the low-dose region on cancer risk assessment. Molecular, cellular, and tissues changes are observed in many key events and change as a function of dose rate. The magnitude and direction of change can be used to help establish an appropriate dose rate effectiveness factor (DREF).

Conclusions: Extensive data on key events suggest that exposure to low dose-rates are less effective in producing changes than high dose rates. Most of these data at the molecular and cellular level support a large (2–30) DREF. In addition, some evidence suggests that doses delivered at a low dose rate decrease damage to levels below that observed in the controls. However, there are some data human and mechanistic data that support a dose-rate effectiveness factor of 1. In summary, a review of the available molecular, cellular and tissue data indicates that not only is dose rate an important variable in understanding radiation risk but it also supports the selection of a DREF greater than one as currently recommended by ICRP (2007 International Commission on Radiological Protection (ICRP). 2007. International Commission on Radiological Protection. 2007. The 2007 recommendations of the International Commission on Radiological Protection. New York: Elsevier; ICRP Publication 103; Ann ICRP 37(2–4). [Google Scholar]) and BEIR VII (NRC/NAS 2006 National Research Council/National Academy of Sciences (NRC/NAS). 2006. Health risks from exposure to low levels of ionizing radiation (BEIR VII Phase 2). Committee to assess health risks from exposure to low levels of ionizing radiation. Washington, DC: National Academy Press. [Google Scholar]).     

生殖细胞中辐射诱导适应性反应的研究Ⅰ 辐射剂量及间隔时间对适应性反应的影响

本文作者利用小鼠初级精母细胞的短期实验和精原干细胞的长期实验，对低剂量辐射的剂量、照射方式和大剂量辐射的剂量以及间隔时间进行了研究。结果证明；１０～２００ｍＧｙＸ射线都能诱导适应性反应出现；大剂量辐射的剂量水平对适应性反应的影响不太明显，即在０．７５～４．５Ｇｙ之间均可见到适应性反应；小剂量辐射与相继大剂量辐射之间的间隔时间对适应性反应的出现有很大影响，即０．５小时，大于和等于２４小时不出现适应性反应；５０ｍＧｙ×４的多次照射和慢性小剂量照射１．１０Ｇｙ￣（６０）Ｃｏγ射线仍可诱导明显的适应性反应出现。这些结果表明，在生殖细胞中可见到辐射诱导的适应性反应现象。     

阳江高本底女性居民低剂量辐射照射与颈动脉中内膜厚度关系的初步研究

目的 探索长期低剂量电离辐射对人群心脑血管疾病的影响。方法 选择阳江高本底地区γ外照射剂量率最高的4个管区,对照地区选择了距中心镇距离与高本底地区所选管区距中心镇距离相近的2个管区,高本底地区和对照地区分别选取50岁以上女性居民各100名,通过超声检查测量颈动脉中内膜厚度;采集外周静脉血样本,测定血液生化指标,包括总胆固醇、甘油三酯、高密度脂蛋白、低密度脂蛋白;测量血压、身高及体重,通过问卷调查收集个人生活史和居住史。同时,依据既往研究所测量的室内外环境地表γ剂量率及调查的年龄别居留因子,估算个人终生累积剂量。结果 阳江高本底与对照地区居民的平均累积剂量分别为（161.2±38.6）和（43.7±7.3）mSv,平均年龄分别为（65.2±10.4）和（60.7±8.0）岁。高本底地区居民颈动脉中内膜厚度左、右两侧分别为（1.0±0.3）和（1.0±0.2）mm,对照地区左右两侧颈动脉中内膜厚度均为（0.9±0.2）mm。多元回归分析显示,调整年龄、血压、体质量指数（BMI）、血脂因素后,个人终生累积剂量为左颈动脉中内膜增厚的一个危险因素（β_左=0.000 7,P<0.05）。不同剂量组（<50,50~,100~,200~ mSv）经调整后左动脉中内膜厚度平均值分别为0.9、1.0、0.9、1.1 mm。结论 长期低剂量辐射可能有加速血管老化、增加动脉粥样硬化的风险。     

小剂量多巴酚丁胺超声负荷检测存活心肌及PCI前后二维观察室壁运动异常变化的临床研究

目的 :评估小剂量多巴酚丁胺超声负荷 (LDDSE)检测存活心肌价值及通过经皮冠脉介入治疗术 (PCI)术后 2周二维超声室壁运动异常变化 ,探讨其观察室壁运动变化的准确性。方法 :18例冠心病患者均行PCI。术前 1周内 ,行LDDSE检查 ,并于术后 2周及 3月复查二维超声。结果 :随着Dob剂量增加 ,检测存活心肌敏感性、准确性增高 (P <0 0 5 ) ,特异性两者无明显变化。PCI(3M)二维超声检测有存活节段 113个 ,坏死节段 15个 ;其中术后 3月评定为存活心肌的 113个节段中 ,有 10个节段在术后 2周被判为坏死节段。PCI(2W)二维超声检测有存活节段 10 6个 ,坏死节段 2 2个。结论 :LDDSE检测存活心肌有较高的价值 ,Dob 10 μg检测存活心肌较Dob 5 μg更敏感、更准确。PCI(2W) 2 DE可以较准确地反映术前术后室壁运动变化。故在一定程度土 ,PCI(2W ) 2 DE可以作为评估存活心肌的标准。