Chromosome Aberrations Induced in Human Lymphocytes by Ultrasoft AlK and CK X-rays

Summary

Induction of structural chromosome aberrations was studied in human peripheral blood lymphocytes irradiated in the unstimulated state with ultrasoft X-rays. Aluminium K X-rays (1·49 keV) and carbon K X-rays (0·28 keV) were used. The frequencies of dicentric aberrations and of excess acentric fragments were found to increase approximately linearly with absorbed dose of both radiations. Carbon X-rays were more effective than aluminium X-rays. The corresponding linear yield coefficients for dicentrics are (3·7 × 10^?1) Gy^?1 and (2·2 × 10^?1) Gy^?1 respectively. At low doses both these radiations are more effective than hard X-rays in producing dicentric aberrations, but at high doses aluminium X-rays are less effective than hard X-rays because of the large positive curvature of the hard X-ray dose-response. The most significant observation of these experiments is that electrons of less than 280 eV, produced by carbon X-rays, are efficient in producing dicentric aberrations. This implies that single local energy events of about 14 ionizations within less than 7 nm are able to produce exchange aberrations.     

Modification of X-ray Induced Chromosome Aberration Frequency by Pre- and Postirradiation Hyperthermia of Human Peripheral Lymphocytes

Summary

Human peripheral lymphocytes (HPL) were used to study the synergistic effects of hyperthermia and X-irradiation. The effects on the chromosome aberration frequencies of different combinations of heat and radiation exposure at different cell cycle phases were analysed at the first mitosis after irradiation. When unstimulated HPL were heated after irradiation with 2 and 3 Gy, respectively, the chromosomal aberration frequencies were significantly higher than following radiation exposure alone. Heat treatment during different phases of the cell cycle and irradiation during the G₂ phase led to an increase in the aberration frequencies when the cells were heat-treated not later than 16 h before radiation. Furthermore we show that the number of breaks increased linearly with the duration of hyperthermia when HPL were heated for periods of 1–15 min at 45°C 32 h before irradiation at 48 h after stimulation. Heat treatment alone during any phase of the cell cycle did not induce chromosome aberrations. The increased aberration frequencies are probably the result of inhibited repair of radiation-induced DNA strand breaks.     

Chromosome aberrations induced in human lymphocytes by an X-radiation accident: results of a 4-year postirradiation analysis

After occupational and medical radiation exposures structural chromosome aberrations may be induced in the lymphocytes of the irradiated persons. Many authors have estimated the radiation dose from the yields of dicentric aberrations. We analysed the influence on the dicentric yield of increasing time intervals between irradiation and blood sampling from a person involved in an X-radiation accident (radiography). During a 4-year follow-up we observed an approximately 7-fold decline of the dicentric yield up to the 25th month and thereafter an almost constant value. Since the decline did not commence until around the 10th month after the exposure, an exponential decrease of dicentric yield with time should be considered with reservation in this study, although it cannot be entirely ruled out. We conclude that in 'biological dosimetry' blood should be sampled as early as possible after the exposure. Furthermore, computation of 'half-times' of lymphocytes to allow for a delay in blood sampling seems uncertain after partial body exposures to high doses. Therefore in such cases dose estimates obtained 1 or more years after irradiation should be considered as minimum values.     

ConA诱导的人淋巴细胞凝集反应的辐射效应

本文用外源性凝集素ConA诱导人淋巴细胞产生凝集反应的实验,观察了⁶⁰Coγ线黑射对淋巴细胞质膜识别功能的生物效应,并结合用松胞素B和秋水仙素两种药物破坏细胞微丝、微管的实验,对电离辐射导致的人淋巴细胞凝集反应抑制效应进行了探讨。实验结果提示: 1.电离辐射和松胞素B对ConA诱导的人淋巴细胞凝集反应都具有抑制效应;2.秋水仙素对ConA诱导的人淋巴细胞凝集反应抑制效应不明显。     

Chromosomal Aberrations in Normal Human Cells Induced by the Auger Effect via Ca Atoms

Purpose: To quantify the Auger effect on chromosomal aberrations via Ca atoms in human cells.

Material and Methods: Exponentially growing human normal fibroblasts (GM05389) were irradiated with 4.047 (CaK‐P), 4.026 (CaK‐L) and 4.067 (CaK‐H) keV X‐rays (corresponding to the resonance absorption edge of the Ca K‐shell and slightly below and slightly above the edge, respectively) using synchrotron radiation at the photon factory (PF) of the High Energy Accelerator Organization located in Tsukuba. Chromosomal aberrations induced by the irradiation were analyzed by the premature chromosome condensation (PCC) method using calyculin A. The dependency of the chromosomal aberrations on the incubation time post 2?Gy irradiation was observed for each energy. Irradiation using 200?kVp conventional X‐rays was also examined as a reference to CaK irradiation.

Results: 1. Soon after irradiation with 2?Gy, the enhancement ratios of CaK‐H X‐rays to CaK‐L X‐rays were 1.21, 1.51 and 2.70 for breaks/gaps, isochromatid breaks and exchanges, respectively. The enhancement ratios of CaK‐P X‐rays to CaK‐L X‐rays were 1.82, 0.98 and 6.30, for breaks/gaps, isochromatid breaks and exchanges, respectively.

2, After a 6‐hr incubation treatment post 2?Gy irradiation, the enhancement ratios of CaK‐H X‐rays to CaK‐L X‐rays were 1.59, 2.03 and 2.14 for breaks/gaps, isochromatid breaks and exchanges, respectively. The enhancement ratios of CaK‐P X‐rays to CaK‐L X‐rays were 1.69, 1.66 and 2.00 for breaks/gaps, isochromatid breaks and exchanges, respectively.

3, Soon after irradiation, the ratios of the efficiencies of CaK‐P X‐rays to those of 200?kVp X‐rays were 1.74, 1.29 and 2.51 for breaks/gaps, isochromatid breaks and exchanges, respectively. And after a 6‐hr incubation treatment, the ratios were 5.50, 1.93 and 1.81 for breaks/gaps, isochromatid breaks and exchanges, respectively.

Conclusions: An effective enhancement of chromosomal aberrations, such as breaks/gaps, isochromatid breaks and exchanges, was caused by Ca K‐shell ionization or excitation. Auger electrons emitted by Ca atoms in irradiated cells appear to have an important role in causing this enhancement. Comparing these efficiencies of chromosomal aberrations with those produced by 200?kVp conventional X‐rays suggests un‐repaired and complicated damage is induced by the X‐rays around the Ca K‐shell resonance absorption edge.     

Chemical Steps Involved in the Production of Mutations and Chromosome Aberrations by X-irradiation in Drosophila

Summary

Post-treatment with hydrocyanic acid results in a significant increase of the mutation frequency in spermatids, if x-radiation is delivered at a high dose-rate, but not after irradiation at a low dose-rate. A greater overall genetic effect of intensity per se has not been observed.

Following radiation at both low and high intensities, post-treatment with cyanide increases the frequency of translocations in spermatids. Consequently, it has been inferred that cyanide causes a prolonged opening of chromosome breaks in spermatids and thus favours the formation of translocations.

Both this finding and the fact that cyanide post-treatment also raises the mutation rate in a ring-shaped chromosome suggest that the increase in lethal frequency due to post-treatment refers not only to position-effect lethals but also to gene mutations and possibly small deletions.

Data relating differential sensitivity in successive broods to oxygen tension are presented. Post-treatment with cyanide is equally effective in raising the mutation rate if high-intensity radiation is given in pure N₂, as in O₂.

It is assumed that cyanide inhibits a mechanism responsible for repair of the initial radiation damage. Recovery from changes leading to lethal gene mutations then seems a metabolic process, possibly connected with respiratory energy. Injury to this repair system is independent of oxygen tension, and the reparable fraction of the initial damage after radiation in N₂ is equal to that after radiation in O₂.     

人淋巴细胞加氚化合物体外培养吸收剂量估算和剂量-效应关系分析

人淋巴细胞分别加六种氚化合物体外培养,测定淋巴细胞内掺八量、动态掺入和标记指数,用所获参数进行吸收剂量估算,并以染色体畸变作为终点观察指标进行剂量一效应关系分析.结果表明,在吸收剂量估算中,考虑了不同氚化合物在细胞内空间和时间分布上的差异,应用依赖于掺入量的累积I酿做剂量估算.有助于揭示氚生物效应本质,为深入研究提供可比数据.     

Effect of Exposure Type and Timing of Injuries in Division I College Football: A 4-year Single Program Analysis

Background: Football players compete with a high risk of injury due to the sport. With the recent efforts to improve safety, the National Collegiate Athletic Association (NCAA) established new terminology to clearly define exposure types and reduce the number of high contact exposures.

Objectives: To compare football injury rates (IR) with a focus on game versus practice, time in season of injury, mechanism of injury and utilizing recent exposure types defined by the NCAA (live contact, full-pads and non-contact).

Methods: Licensed medical professionals monitored a college football program regular season from 2012–2015. Each injury was classified by timing of the injury, mechanism of injury, and whether it occurred in game or practice. Player attendance and type of exposure (non-contact, full-pad or live contact, which involves live tackling to the ground and/or full-speed blocking and can occur in full-pad or half-pad (‘shell’) equipment) was documented. IR were calculated per 1000 athlete-exposures (AE). Mid-exact P tests compared rates between variables.

Results: The game IR was over three times as high as the practice IR (p < .001). Live contact exposures had the greatest IR of 5.702/1000 AE and were seven times more likely to produce an injury compared to non-contact exposures (p < .001); whereas, live contact exposures were about two times more likely to produce an injury compared to full-pad exposures (p = .004). The majority of injuries observed occurred from a contact mechanism (IR: 2.508/1000 AE). The highest IR during the fall football season occurred in the pre-season at 5.769/1000 AE.

Conclusion: Overall IR observed in this cohort were lower than prior studies published before recent NCAA rule changes and guideline implementation to improve athlete safety. Athletes in this cohort were at significantly increased risk of injury from live contact exposures.     

Anteromedialization of the tibialtubercle: A 4- to 12-year follow-up

In this article, we review of 36 patients (42 knees, 6 bilateral) that underwent anteromedialization of the tibial tubercle for patellar malalignment and cartilage breakdown between 1982 and 1990. The average follow-up was 8.2 years (minimum 4.4). Patients completed questionnaires, visual analog scales, and a modified Lyshohn scale. Thirty-six patients (with 42 affected knees) returned questionnaires of which 19 patients (22 knees) were seen in the office for long-term follow-up evaluation. Good to excellent results were subjectively reported by 86% (36 of 42) of the patients. On physical examination, 19 of 22 knees had an excellent or good result. The average score on the modified Lysholm scale was 83.5 (range, 15 to 100). After surgery, 7 of 36 patients returned to heavy labor, 9 of 36 to moderate work, and 18 of 36 to light duty. One year after surgery, 95% (40 of 42) said they would undergo the procedure again given similar circumstances, and 67% said they were satisfied with their level of recreational activity. Anteromedialization of the tibial tubercle when done properly is a successful method for correcting patellar malalignment and relieving pain from mild to moderate patella cartilage breakdown. This study is based on objective and subjective long-term follow-up.     

中国民航1980～2009年间运输飞行事故人的失误分析

目的 用中国民航人的失误分析系统(CN-HFACS)研究人的失误各类别在运输飞行事故致因因素中的重要程度.方法 分析35起运输飞行事故调查报告,从个人的不安全行为、不安全行为的前提条件、不安全的管理、组织影响、政府监管因素5个层面进行分析.结果 个人的不安全行为及其前提条件在运输飞行事故人的失误类别中占76%;个人的不...     

Human factors in aircraft incidents: results of a 7-year study

Human error causes or contributes to considerably over half of all aviation mishaps. This report describes a 7-year study of aircraft incident data conducted in an attempt to further our understanding of the phenomenon of human error. The study of incidents as a surrogate for aircraft accidents is relevant only if incidents constitute a population or universe of which accidents are a subset. This assumption has been examined in a study of over 35,000 reports of aviation incidents collected from 1976-83 by the NASA Aviation Safety Reporting System. One-third of the reports involve conflicts among aircraft. The most common single-aircraft anomalies in flight involve altitude or track deviations. The most common controller errors involve failure to coordinate traffic with other elements of the air traffic control system. Analysis of these reports indicates that both human and system factors contributing to human errors can be identified. Many other incidents involve shortcomings specifically of the human, rather than of the system. Failures of control are rare in this series, but failures of decision-making and cockpit resource management are frequent. Boredom, complacency and ennui appear to underlie some failures, while very high workloads are associated with others. These data indicate that at least several categories of aircraft accidents involving operational and human factors are, in fact, subsets of populations of incidents containing the same elements. The environment in which an incident occurs is extremely important in determining its outcome. It is concluded that aviation incident reports are a necessary and important instrument in safety surveillance.     

260例新生儿听力筛查初筛结果分析

目的探讨影响新生儿听力筛查初筛未通过的原因,为选择合适的初筛时间,提高初筛通过率提供依据。方法采用GSI7O全自动耳声发射筛查仪对我院2009年4月～7月出生的260例新生儿进行听力筛查,对筛查结果进行回顾性分析。结果 260例新生儿中,初筛通过226例,占86.15%。初筛未通过36例,占13.85%。新生儿胎龄和体重与初筛通过率密切相关,差异有统计学意义（P〈0.05）。结论根据新生儿出生时胎龄、体重不同选择合适的初筛时间,可提高初筛通过率,降低假阳性率。     

Chromosome Aberrations Following Irradiation with High-energy Protons and Their Secondary Radiation: A Study of Dose Distribution and Biological Efficiency Using Root-tips of Vicia Faba and Allium Cepa

Summary

Some radiological properties of a 185 mev proton beam were stuided with root-tips of bean and onion seedlings.

The relationship between dose and number of abnormal metaphases was investigated at different depths of penetration in Lucite. The effect, found in the final part of the range of penetration, was higher than expected when the physical depth-dose to surface-dose ratio is considered. The difference is partly attributed to a variation of the relative biological efficiency.

The enhancing effect of oxygen was studied at high and low energies. It was found to be nearly constant.

The relative biological efficiency of 170 mev protons as compared with 180 kv roentgen rays for producing chromosome aberrations was found to be 0·7.

The chromosome-breaking efficiencies of the secondary radiations from proton-irradiated tissue and brass were studied. The results indicate that the effects of secondary radiation may be neglected in therapeutic procedures.     

Stance instability in preclinical SCA1 mutation carriers: A 4-year prospective posturography study

ObjectiveWe aimed to study postural balance in preclinical Spinocerebellar ataxia type 1 (SCA1) mutation carriers to identify and observe specific motor functional deficit before evident clinical manifestation.MethodsParticipants were 9 asymptomatic SCA1 mutation carriers (6 M/3F), aged 31.8 ± 7 years (range 22–44), and 17 age-matched non-carrier controls (5 M/12F) (age 18–42). Subjects underwent postural tests on a force platform (Tetrax^®-IBS, Sunlight Medical Ltd.) with and without visual feedback. Amount of body sway was represented by stability index (ST). Tests were repeated after 2- and 4-years. Estimated years to onset were calculated.ResultsIn controls, ST was unchanged from baseline to 4-year evaluations in all standing conditions. SCA1 mutation carriers performed similarly to controls in the postural tasks with open eyes, whereas in conditions without visual feedback SCA1 carriers had significantly higher ST than controls at all longitudinal evaluations. Close-to-disease onset carriers (≤7years) showed more prominent time-dependent stance abnormalities (p < 0.0001 for all comparisons).ConclusionsTraceable and progressive postural abnormalities can be observed in preclinical close-to-onset SCA1 carriers. Quantitative analysis of stance could represent a promising outcome measure in clinical trials including preclinical subjects.     

Management of inferior pancreaticoduodenal artery aneurysms: A 4-year,single center experience

Inferior pancreaticoduodenal artery aneurysms are uncommon visceral artery aneurysms usually difficult to resect, and, if untreated, have a propensity to rupture with catastrophic results. We reviewed the clinical and treatment records of four patients encountered in our institution within the last 4 years. Three patients presented as bleeding emergencies from single aneurysms and were successfully treated by transcatheter embolization using coaxial technique and a variety of embolic agents. One nonemergent, asymptomatic patient had surgical resection of two inferior pancreaticoduodenal artery aneurysms due to unfavorable anatomy for embolization. Embolization therapy appears to be the treatment of choice in the emergency setting. Patients with unsuitable anatomy for embolization may still re quire surgical intervention.     

HDAC抑制剂MS-275诱导人肺腺癌细胞系A549基因表达谱分析

目的 研究HDAC抑制剂MS-275对人肺腺癌A549细胞基因表达谱的影响,探讨MS-275抗肿瘤的分子机制.方法 运用制备的包含8 064个人类基因的cDNA芯片检测MS-275诱导人肺腺癌A549细胞基因表达谱的变化.结果 MS-275(2μmol · L-1)处理A549细胞16h后,cDNA芯片分析筛选出MS-275对A549细胞的影响基因803个,其中上调基因440个,下调基因363个,其中包括许多与细胞凋亡、细胞分化、DNA修复等相关基因如p21、DR6.结论 MS-275通过外源性凋亡信号、内源性凋亡信号和细胞周期阻滞等多种分子机制诱导A549细胞凋亡.     

近12年中国民航人因事故与事故征候的分类研究

目的：对中国民航1990～2001年期间发生的人因事故征候和飞行事故进行分类研究。方法：运用Reason事故链模型,结合中国民航的传统分类方法,制订人因事故与事故征候分类标准,在此基础上按分类标准进行分类统计和分析。结果：1)在飞行的各个阶段中,滑行和巡航阶段小于间隔飞行的事故征候发生的百分比高于起飞、爬升、下降以及进近阶段。2)事故征候的主要类型为偏出、冲出跑道,危险接近,擦机尾或翼尖、发动机以及地面撞障碍物。3)飞行事故的主要表现形式是机组原因造成飞机失控、撞山以及冲出跑道。4)基本驾驶术有所下降,主要表现为修正偏差的能力不足。5)机组错误的主要表现是操纵不当、违反规章程序飞行、迷航及飞错高度。结论：不良的驾驶舱资源管理技能是影响我国民航飞行安全的主要因素,这与国际上的研究相符。但事故征候高发阶段、机组错误的类型和表现形式等,与国际上航空发达国家相比差异较大,具有明显的特点。要进一步改善我国民航的航空安全水平,必须针对我国民航的特点,加强对机组人员驾驶舱资源管理技能的训练。