直线加速器十年故障分析总结

目的分析和总直线加速器十多年来的故障。方法根据十多年来的故障维修记录，统计和分析直线加速器各阶故障率及故障特点。结果直线加速器使用早期由于机器不稳定故障率比较高，使用中期及其比较稳定，故障率比较低，使用后期由于零部件老化，故障率比较高。     

安徽省X射线诊断受检者剂量水平调查

目的　了解安徽省X射线诊断受检者体表剂量水平。方法　体表剂量监测按国家标准 ,采用热释光剂量计。结果　胸部摄片受检者的体表剂量最低 ,为 0 .39～ 0 .5 3mGy ,比胸部透视平均体表剂量减少 88.6 6 %。结论　减少或控制透视比例 ,降低受检者群体的体表剂量 ,以减少医疗照射对人体造成的危害。     

Perceptions of the at-risk nonsmoker: are potential intervention topics being overlooked?

This research is supported in part by Arizona Disease Control and Research Commission (ADCRC), Grant #9904 (M. Burgoon, PI). This study assesses how adolescent nonsmokers, at-risk smokers, and smokers differ in perceptions of smoking harms, benefits, and safety. While small differences exist when comparing attitudes and knowledge concerning short- and long-term benefits of smoking, large differences arise when attitudes and knowledge concerning the short-term benefits and the safety of casual smoking are compared.     

Postsynaptic potentiation of end-plate currents in the rat diaphragm during variation in synaptic acetylcholinesterase activity

Leningrad University. (Presented by Academician of the Academy of Medical Sciences of the USSR S. N. Golikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 5, pp. 458–460, May, 1991.     

The Decline in Serum Albumin after Conversion to High Flux, High Efficiency Dialysis

Abstract: Hypoalbuminemia among chronic hemodialysis patients is recognized as a poor prognostic sign. We observed that many of our chronic patients had a progressive decrease in their plasma albumin concentrations after they were converted to high flux, high efficiency dialysis from conventional dialysis mode. This change occurred in the absence of changes in the KTIV and protein catabolic rate (per) normalized to body mass. When nitrogen losses were measured, we found no difference in the dialysate concentrations of urea, alpha amino nitrogen, uric acid, or total nitrogen when high flux polysulfone was compared with high efficiency Cuprophan. While urea was the predominant nitrogen solute in all dialysate samples, there were some with a large gap between total and urea nitrogen. Alpha amino nitrogen losses, expressed as leucine equivalents, were substantial, ranging from 8. 4 to 9. 8 g/3. 5 h dialysis treatment. We believe that the increased losses of nitrogen experienced by patients after their conversion to a more efficient method of dialysis and not compensated for by a spontaneous increased intake of protein led to the observed fall in plasma albumin. Both urea and amino acid nitrogen losses need to be accounted for when achievement of higher KTIV dialysis is pursued.     

In-vitro synthesis of steroid hormones in corpora lutea from normal women and women treated with 300 micrograms norethisterone.

The in-vitro oestradiol (E2) and progesterone (P) production by corpora lutea (CL) obtained at sterilization from 30 untreated women and 43 women treated with norethisterone (NET) 300 micrograms daily was measured. The CL were obtained at different stages of the luteal phase in the untreated women [luteinizing hormone (LH) 0 to +3, n = 7; LH +4 to +7, n = 7; LH +8 to +11, n = 9; LH +12 to menses, n = 7] and on days LH +8 to +11 or cycle days 22 to 26 in the NET-treated women. In the treated women, four types of ovarian reaction were identified. Four women showed ovarian reaction Type A (completely inhibited ovarian activity), 14 women Type B (marked follicular activity, but no luteal function), 12 women Type C (normal follicular activity, followed by insufficient luteal function) and 13 women Type D (apparently normal follicular and luteal activity). The CL were incubated in Eagle's medium with and without stimulation by human chorionic gonadotrophin (HCG) for 2 and 4 h. In the untreated women, P and E2 production increased significantly with both incubation time and stimulation by HCG throughout the luteal phase, except in the late luteal phase (LH +12 to menses) where P increased (P less than 0.01) only after 4 h stimulation by HCG. The maximal production of P was found after 4 h incubation with HCG stimulation of CL tissue in the early-mid luteal phase (LH +4 to +7).(ABSTRACT TRUNCATED AT 250 WORDS)     

模拟调强技术照射鼻咽低分化鳞癌细胞的生物效应机制研究

Objective To study the altered radiobiological effect of simulative intensity-modulated radiotherapy (SIMR) in cultured human nasopharyngeal carcinoma (NPC) cells and the related mechanism. Methods Single cell suspension of exponentially growing CNE-2 cells, a poor differentiated NPC cell line, was seeded and cultured for 12 hours, then the cells were irradiated in two different models by 6 MV X-ray beams at 3 Gy/min. In single fraction irradiation (SFR) model, cells were irradiated a single fraction of 0, 2, 4, 6 or 8 Gy within 0 to 3 minutes. In S1MR model, cells were irradiated 0, 2, 4, 6 or 8 Gy in 5 frac-tions with interval of 8.0-8.5 minutes between. Clonogenic assay was performed to determine the radiosen-sitivity. Cellular apoptosis was measured by flow cytometry. RT-PCR was used to detect mRNA expressions of Bax and Bcl-2, Respectively. Results Compared with SFR group, the survival fraction in SIMR group was higher at all the dose levels. The values of α, β, D0 and Dq were higher in SIMR group than in SFR group. At dose levels of 2 Gy, 4 Gy and 6 Gy, The early and late apoptotic cells in SIMR group were lower than in SFR group (21.20%: 15.89%, F=18.51, P=0.020;13.00%: 10.20, F=15.67, P=0.040).The mRNA expression of Bax was upregulated in a dose-dependent manner in the both groups. Compared with SFR group, the mRNA expression of Bax in SIMR group was lower at all the dose levels (Mean value of 76.75% : 62.50%, F =36.57, P =0.000). Bcl-2 mRNA expression at every dose level had no significant difference between the two groups (Mean value of 29.25% : 29.75%, F=0.74, P=0.800). Conclusions Prolonged delivery time in SIMR model can decrease the radiobiological effects.     

眼球孤立性脉络膜血管瘤的HR-MRI表现

目的　探讨眼球孤立性脉络膜血管瘤的高分辨率磁共振 (HR MRI)影像学特征 ,进一步提高诊断水平。资料与方法　回顾性分析诊断明确的孤立性脉络膜血管瘤 16例共计 17个病灶的位置、数目、形态、大小、MRI信号、强化情况、有无合并视网膜脱离及有无视神经和眼外侵犯等。所有病例均行HR MRI及增强扫描 ,部分病例行脂肪抑制。结果　 17个病灶中的 16个呈扁丘状位于眼球内壁的后极。 15个病灶厚度 <5mm ,平均厚度为2 .9mm。病灶边缘清晰 ,T1WI上呈轻度高信号者 16个 ,T2 WI上呈等信号者 15个 ,增强扫描显著强化者有 12个。 3例合并视网膜脱离 ,在T2 WI上多呈等信号 ,T1WI上呈轻度高信号者 ,均无强化。无视神经及眼外侵犯病例。结论　 94 %孤立性脉络膜血管瘤的HR MRI表现具有特征性 ,表现为位于眼球内壁后极的较小、基底较宽、边缘清晰的扁丘状病灶。其T1WI信号高于玻璃体 ,T2 WI信号等于玻璃体 ,增强扫描瘤体显著强化。明确其HR MRI影像学特征有助于临床与恶性葡萄膜黑色素瘤相鉴别 ,避免不必要的眼球摘除     

高压液相色谱纯化肾综合征出血热病毒血凝素及其性状分析

用吐温８０－乙醚（ＴＥ）法、蔗糖－丙酮（ＳＡ）法、丙酮－乙醚（ＡＥ）法分别从肾综合征出血热病毒（ＨＦＲＳＶ）感染的Ｖｅｒｏ－Ｅ６细胞培养和乳小白鼠脑组织中制备病毒血凝素（ＨＡＮ），定量对比证明其制备效果，结果无明显差异。粗制ＨＡＮ经高压液相色谱（ＥＰＬＣ）纯化，有４个洗脱峰，血凝活性物质存在于峰１。纯化ＨＡＮ在ＳＤＳ－ＰＡＧＥ中呈单一区带，分子量５６．６ＫＤ，ＨＡＮ相对含量７９．６％。纯化ＨＡＮ在蔗糖密度梯度液中有一条１．１５～１．１６ｇ／ｃｍ３的沉淀，粗制ＨＡＮ有３条沉淀。电镜观察纯化ＨＡＮ中为大小相等的球状颗粒。粗制ＨＡＮ的高密度沉淀中可见到病样颗粒。对几种常用消毒剂、氧化剂、去垢剂对ＨＡＮ的灭活作用做了实验对比观察。     

PHA RMA COKINETICS OF CUPRIC－BIS（SALICYLALDEHYDE－2－FURA NTHIOCA RBOXY－HYDRAZONATE） DICHLORIDE（CSFTCH） IN RABBITS

ＰＨＡＲＭＡＣＯＫＩＮＥＴＩＣＳＯＦＣＵＰＲＩＣ－ＢＩＳ（ＳＡＬＩＣＹＬＡＬＤＥＨＹＤＥ－２－ＦＵＲＡＮＴＨＩＯＣＡＲＢＯＸＹ－ＨＹＤＲＡＺＯＮＡＴＥ）ＤＩＣＨＬＯＲＩＤＥ（ＣＳＦＴＣＨ）ＩＮＲＡＢＢＩＴＳ￥ＧａｏＹｕｎｓｈｅｎｇ；ＺｈｕＹｕｙｕｎ（...