雪莲对正常及辐射损伤小鼠巨噬细胞功能的影响

本文研究了５０％雪莲水煎剂对正常及５ＧＹ６０Ｃｏ一次性全身照射ＢＡＬＢ／Ｃ小鼠巨噬细胞功能的影响,结果表明：口服５０％雪莲水煎剂能增强巨噬细胞吞噬鸡血球及分泌肿瘤坏死因子（ＴＮＦ）的能力,与相应对照组比较具有显著性差异,提示中药雪莲具有扶正固本提高机体防御机能及促进辐射损伤修复的作用。为该药的临床应用提供了科学依据。     

射线诱导在体造血细胞凋亡的量时效关系的研究

以4—10Gy射线在体损伤的小鼠为模型,应用DNA电泳和流式细胞术等方法证实细胞凋亡是射线损伤在体骨髓造血细胞的途径之一,发现射线诱导的造血细胞凋亡有明显的量效和时效关系。4、6、8和10Gy照射后,细胞凋亡发生率均表现为升高-降低过程,各剂量诱导的凋亡发生率峰值分别出现在照后12、8、4和4h,6和8Gy诱导的凋亡发生率已达最高水平,约为30％,10Gy诱导的凋亡反而要低。上述结果表明,诱导细胞凋亡是射线损伤骨髓造血细胞的一个重要途径,而且凋亡的发生率受照射剂量和照后时间的影响。因此,深入研究射线诱导的细胞凋亡,将有助于揭示射线损伤造血功能的机理。     

五年制临床医学专业防原医学课程标准的制定与探索

防原医学是为五年制临床医学专业开设的一门必修的军事医学课程,理解和掌握防原医学知识,是成为具有全面技能的军事医学人才的基础。为了通过本门课程的学习,更好地培养高素质的新型军事医学人才,本文结合第四军医大学五年制临床医学专业学员的培养目标和实际情况,对课程标准的内容制定和实施进行思考,探索课程标准下的防原医学教学模式与方法,旨在进一步提升教学效果,造就新时期军事变革条件下的优秀人民军医。     

Wnt/beta-catenin信号通路关键因子在放射性肺纤维化中的作用

目的：观察直线加速器X射线照射对人肺成纤维细胞(HLFs)Wnt/beta-catenin 信号通路关键信号因子的影响并探讨其意义。方 法：HLFs分别经直线加速器0Gy、5Gy、8Gy X线照射后,MTT 比色法检测其增殖活性,筛选合适照射剂量。人肺成纤维细胞分为 照射组(R 组)和正常对照组(C 组),R 组经直线加速器X射线,5 Gy 照射24 h后,免疫荧光检测成纤维细胞alpha-SMA表达,Western blot检测成纤维细胞中GSK-3beta、p-GSK-3beta表达。结果：X 线5 Gy照射剂量可使人肺成纤维细胞增殖活力增强,较0 Gy、8 Gy增 殖曲线明显。照射组人肺成纤维细胞形态较正常组有明显差异。照射组人肺成纤维细胞琢-SMA,p-GSK-3beta表达水平升高, p-GSK-3beta/GSK-3beta比值升高,与正常对照组比较均有统计学意义(P<0.05)。结论：Wnt/beta-catenin 信号通路在放射性肺损伤的发生 发展中起调控作用,可能为放射性肺纤维化的治疗提供了新视角。     

放疗联合食管支架对晚期食道癌患者预后影响的COX分析

目的:分析放疗联合食管支架对晚期食道癌患者预后影响。方法:选取我院收治晚期食道癌患者90例,经西医诊断标准经病理学及CT检查确诊为晚期食道癌,根据治疗方法不同分为实验组(放疗联合食管支架术)与对照组(食管支架术)。比较患者肝、肾功能,及生存率。采用Cox分析法对患者预后与放疗的相关性分析。结果:两组患者半年、1年、3年、5年生存率相比较,实验组与对照组相比较,生存率升高,差异具有统计学意义(P0.05);经COX分析,食管癌患者的生存率与患者的淋巴结转移书、TNM分期以及是否放疗有关(P0.05);经COX分析后可见,是否有食管瘘、是否根治术、病理分型、TNM分期、是否放疗为影响食管癌患者生存的独立影响因素(P0.05)。结论:是否有食管瘘、是否根治术、病理分型、TNM分期、是否放疗是食管癌患者生存的独立影响因素。术后的放疗治疗对患者的生存有积极意义。     

Determination of Sample Sizes for Demonstrating Efficacy of Radiation Countermeasures

Summary .  In response to the ever increasing threat of radiological and nuclear terrorism, active development of nontoxic new drugs and other countermeasures to protect against and/or mitigate adverse health effects of radiation is ongoing. Although the classical LD₅₀ study used for many decades as a first step in preclinical toxicity testing of new drugs has been largely replaced by experiments that use fewer animals, the need to evaluate the radioprotective efficacy of new drugs necessitates the conduct of traditional LD₅₀ comparative studies ( FDA, 2002 ,  Federal Register   67, 37988–37998). There is, however, no readily available method to determine the number of animals needed for establishing efficacy in these comparative potency studies. This article presents a sample-size formula based on Student's  t  for comparative potency testing. It is motivated by the U.S. Food and Drug Administration's (FDA's) requirements for robust efficacy data in the testing of response modifiers in total body irradiation experiments where human studies are not ethical or feasible. Monte Carlo simulation demonstrated the formula's performance for Student's  t , Wald, and likelihood ratio tests in both logistic and probit models. Importantly, the results showed clear potential for justifying the use of substantially fewer animals than are customarily used in these studies. The present article may thus initiate a dialogue among researchers who use animals for radioprotection survival studies, institutional animal care and use committees, and drug regulatory bodies to reach a consensus on the number of animals needed to achieve statistically robust results for demonstrating efficacy of radioprotective drugs.     

Normoxic polymer gel dosimetry using less toxic monomer of N-isopropyl acrylamide and X-ray computed tomography for radiation therapy applications

Background

Polymer gel dosimetry has been used extensively in radiation therapy for its capability in depicting a three dimensional view of absorbed dose distribution. However, more studies are required to find less toxic and more efficient polymers for application in radiotherapy dosimetry.

Aim

The purpose of this work was to evaluate the N-isopropyl acrylamide (NIPAM) gel dosimetric characteristics and optimize the protocol for X-ray computed tomography (CT) imaging of gel dosimeters for radiation therapy application.

Material and methods

A polymer gel dosimeter based on NIPAM monomer was prepared and irradiated with ⁶⁰Co photons. The CT number changes following irradiation were extracted from CT images obtained with different sets of imaging parameters.

Results

The results showed the dose sensitivity of ΔN_CT (H) = 0.282 ± 0.018 (H Gy⁻¹) for NIPAM gel dosimeter. The optimized set of imaging exposure parameters was 120 kV_p and 200 mA with the 10 mm slice thickness. Results of the depth dose measurement with gel dosimeter showed a great discrepancy with the actual depth dose data.

Conclusion

According to the current study, NIPAM-based gel dosimetry with X-ray CT imaging needs more technical development and formulation refinement to be used for radiation therapy application.     

Ultrasound and matter--physical interactions

The basic physical characteristics of ultrasound waves are reviewed in terms of the typical displacements, velocities, accelerations and pressures generated in various fluid media as a function of frequency. The effects on wave propagation of interfaces are considered, and the way in which waves are reflected, transmitted and mode converted at interfaces introduced. Then the nonlinear propagation of high amplitude ultrasound is explained, and its consequences, including the generation of harmonic frequencies and enhanced attenuation, considered. The absorption of ultrasonic waves and the resulting heat deposition in absorbing media are described together with factors determining the resulting temperature rises obtained. In the case of tissue these include conduction and perfusion. The characteristics of cavitation in fluid media are also briefly covered. Finally, secondary nonlinear physical effects are described. These include radiation forces on interfaces and streaming in fluids.     

Development and evaluation of intermediate frequency magnetic field exposure system for studies of in vitro biological effects

We have developed an intermediate frequency (IF) magnetic field exposure system for in vitro studies. Since there are no previous studies on exposure to heating-frequency magnetic fields generated from an induction heating (IH) cook top, there is a strong need for such an exposure system and for biological studies of IF magnetic fields. This system mainly consists of a magnetic-field-generating coil housed inside an incubator, inside which cultured cells can be exposed to magnetic field. Two systems were prepared to allow the experiment to be conducted in a double-blind manner. The level of the generated magnetic field was set to 532 microT rms in the exposure space, 23 kHz, 80 times the value in the International Commission on Non-ionizing Radiation Protection (ICNIRP) guidelines, with a spatial field uniformity better than 3.8%. The waveforms were nearly sinusoidal. It was also confirmed that the parasitic electric field was 157 V/m rms and the induced electric field was 1.9 V/m rms. The temperature was maintained at 36.5 +/- 0.5 degrees C for 2 h. Furthermore, leaked magnetic flux density was 0.7 microT rms or lower at extremely low frequency (ELF) and IF in the stopped system when the other system was being operated, and the environmental magnetic flux density was 0.1 microT rms or lower at the center of the coils. As a result, it was confirmed that this system could be successfully used to evaluate the biological effects of exposure to IF magnetic fields.     

Thermal melanism in ectotherms

Whether melanism plays a significant role in thermoregulation has been a persistent question in studies of thermal biology of ectotherms. This review provides a synthesis of the thermal melanism hypothesis which states that dark individuals (i.e. lower skin reflectance) are at an advantage under conditions of low temperature since they heat up faster than light individuals at a given level of solar radiation. Although skin color is an important trait in the thermal biology of ectotherms, it has rarely been explored in non-insect models. We draw on the available literature to assess the validity of four key assumptions that underlie this hypothesis. Ample support was found for the assumption that melanistic diurnal species inhabit cooler areas than lighter species and that melanism results in greater fitness in cold climates. By contrast, little direct support could be found for the assumption that there is a consistent melanism–body size tradeoff. Finally, the assumption that color, thermal physiology and behavior are coadapted has some support but requires further investigation. Overall, the functional, molecular and adaptive mechanisms of thermal melanism await further study.