辐照食品的电子自旋共振波谱(ESR)研究

目的 研究市售辐照食品的电子自旋共振波谱(ESR),探索有效的辐照食品卫生监督方法。方法 对市售食品采样,经3~20 kGy剂量范围进行辐照处理,测定其电子自旋共振波谱,研究辐照后产生的自由基浓度与辐照剂量的关系。结果 ESR信号强度随剂量增加而增加,样品在室温下保存98 d,ESR信号强度逐渐减弱,但信号不会消失。结论 辐照食品的剂量与ESR信号关系清晰,可作为建立ESR方法检测辐照食品的方法。     

ARDS时HO抗氧化作用机制初探

目的 探讨血红素氧合酶(HO)抗氧化性对急性呼吸窘迫综合征(ARDS)的保护作用及其机制。方法 采用电子自旋共振(ESR)技术直接测量活性氧(ROS),并结合化学发光法和脂质过氧化产物测定等技术来研究ARDS发生发展过程中HO对自由基的影响。结果 ESR结果显示,大鼠注射OA后10min ROS含量即升高,30min达到高峰,以后逐渐下降;HO组未见ROS显著增加;而化学发光法定量检测和SOD检测结果与ESR波谱显示的结果完全一致,MDA从检测结果则提示Hb诱导HO有一定的副作用。结论 ROS可能是ARDS启动的主要病因;HO有一定的抗氧化能力。     

活性氧自由基在ARDS发病机制中作用的实验研究

目的 探讨活性氧(ROS)自由基在急性呼吸窘迫综合征(ARDS)发病机制中的作用。方法 采用电子自旋共振(ESR)技术直接测量ROS,并结合超微弱发光法、化学发光法等技术分析鉴定了RPS的种类。结果 ESR结果显示,大鼠注射OA后10min ROS含量即升高,30min达到高峰,以后逐渐下降;利用超微弱发光法,投用不同ROS的清除剂得出OA型ARDS发病中起主要作用的ROS是超氧阴离子(02^-),而化学发光法定量检测结果与ESR波谱显示的结果完全一致。结论 ROS的改变早于肺毛细血管内皮(PCEC)损伤和病理形态的发生,ROS可能是ARDS启动的主要病因;OA型ARDS发病中起主要作用的ROS是02^-,今后在临床上可针对性应用SOD或SOD类似物来进行治疗。     

2例严重的~(60)Co放射事故受照人员的牙齿剂量估算

目的用电子自旋共振方法对山东事故中两例受照人员的3颗牙齿进行剂量估算。方法将受照人员的牙齿经过处理后得到牙釉质样品,进行ESR信号测量,将样品ESR信号的相对强度代入本实验室建立的牙釉质剂量响应曲线后,得到的3颗牙齿的吸收剂量。结果两例受照人员牙釉质ESR吸收剂量剂量分别为:受照人A的牙齿剂量为26.1~29.4Gy;受照人B的两颗牙齿剂量分别为14.9~18.3Gy,15.2~18.5Gy。结论两例受照人员牙釉质ESR剂量测量方法为大剂量照射事故剂量估算提供了一种重要的依据。     

辐照与真空包装对即食肉制品中单增李斯特氏菌及腐败菌杀灭作用的研究

通过模拟样品污染单增李斯特氏菌的方法 ,对 15 0件真空包装的烤鸭、烧鸡和熟肉制品进行了杀菌的辐照研究 ,结果表明 :当样品染菌量为 1 5× 10 3 ～ 2 3× 10 3 cfu g时 ,杀菌的最低辐照剂量为 2 5kGy ;单增李斯特氏菌模式株 5 40 0 4比分离株X2 0、G4、g2对辐照的低抗力强 ;还对 15 0件样品中的腐败菌作了辐照实验 ,其中杀灭烤鸭中的腐败微生物所需最低剂量为 10kGy,烤鸡为 15kGy ,熟肉制品为 2 0kGy。     

控制血压对高血压患者左心室质量及几何构型的影响

目的:探讨长期有效控制血压对高血压患者左心室质量(LVM)及相对室壁厚度(RWT)的影响。方法:110例高血压患者严格控制血压在目标水平内1年后,比较治疗前后LVM和RWT的变化。结果:治疗一年后血压由基础的(168.55±18.74/89.9±14.0)mmHg下降到(130.65±11.09/74.95±7.90)mmHg(P<0.0001),LVM由基础的(278.71±70.83)g下降到(258.15±62.15)g(P<0.0001),RWT由基础的0.53±0.11下降到0.49±0.09(P<0.0001)。结论:长期有效控制血压能明显逆转高血压患者的左心室肥厚(LVH)和改善左心室几何构型。     

外源性双歧杆菌对肠外营养幼兔肠道益生菌的影响

目的:研究外源性双歧杆菌对肠外营养(PN)幼兔肠道益生菌的影响。方法:生后2w的新西兰种白兔24只,分成对照组(n=7)、PN组(n=9)和PN+双歧组(n=8)。对照组为兔食喂养,PN组幼兔完全肠外营养,PN+双歧组幼兔口服青春双歧杆菌0.5×108/d,10d后自直肠取出新鲜粪便。应用SYBR Green I Real-time PCR法,定量检测粪便中双歧杆菌和乳杆菌含量。结果:Real-time PCR法的检测限最低为102PFU,凝胶电泳证实合成探针具有属特异性。粪便细菌定量结果显示,PN组幼兔湿粪(0.05g)中双歧杆菌和乳杆菌含量(对数值)分别为4.62±0.24和4.29±0.49,显著低于对照组(分别为5.84±0.92、5.14±1.07log)和双歧组(6.41±0.39,5.46±0.61log)。结论:SYBR Green I Real-time PCR法能够准确、迅速地对幼兔粪便双歧杆菌和乳杆菌进行定量检测。PN幼兔口服双歧杆菌后,其粪便中双歧杆菌和乳杆菌含量显著增加。     

钴60γ射线灭活人工骨钉PRV病毒效果验证

目的:验证钴60辐照灭活猪源性人工骨钉中指示病毒PRV活性的有效性。方法:首先利用CPE法测定不同辐照剂量γ射线灭活样品后指示病毒的感染活性,初步确定有效辐照剂量;然后利用三批样品对该辐照剂量灭活效果进行验证,辐照前后人工骨钉中指示病毒的滴度采用96孔板CPE法滴定。结果:CPE法测定结果显示,经20kGy及以上辐照剂量处理的样品中指示病毒PRV不能使宿主细胞PK-15出现细胞病变;三批样品经20kGy辐照剂量处理后,指示病毒PRV滴度下降值⊿lgTCID50分别>4.06,>4.75,>4.28,⊿lgTCID50值均大于4。结论:辐照剂量为20kGy的钴60γ射线辐照猪源性人工骨钉可以作为灭活PRV的有效手段。     

FAAS法测定大学生头发中金属元素及含量分析

利用火焰原子吸收光谱法,对192名大学生头发中Zn、Cu、Ca、Mg元素含量进行了检测,其中男生64名,女生128名,年龄均为19~23岁。通过统计计算,确定了正常值范围(-x±s,μg/g),Zn:192.7235±33.0187,Cu:9.2831±1.9047,Mg:58.0734±19.7817,Ca:788.3940±296.4418。为改善大学生群体的饮食结构、生活习惯提供了基础数据。     

尿中百草枯的快速检验

目的:拟建立一种快速检测百草枯的方法。方法:应用传统的分光光度法来定性定量尿中的百草枯。结果:在线性范围0.5~10μg/m l内,回收率达到101.4%±3.82%。此方法曾被用来检测一例疑似百草枯中毒患者。结论:适用于快速定性定量尿中的百草枯含量。     

ESR investigation of sucrose radicals produced by 0.25?4.5 Gy doses of X-ray irradiation

We investigated stable radicals produced by 0.25−4.5 Gy doses of X-ray irradiation of sucrose. Electron spin resonance (ESR) is able to observe the signal from sucrose irradiated at 0.25 Gy. The ESR signal intensity of the radicals is related to the accumulated dose, and it increases linearly with increasing absorbed dose. In addition, we examined the effect of dose rate (0.50−1.5 Gy/min) on the signal intensity of the irradiated sucrose. The stable radical production did not exhibit dose rate dependence. In addition, the peak corresponding to the irradiated glucose was observed to increase more with increasing absorbed dose than the peak corresponding to irradiated fructose. Therefore, the present ESR results regarding the 0.25−4.5 Gy irradiation of sucrose provide new insights into a possible sucrose ESR dosimeter.     

Electron spin resonance dosimetric properties of bone

The characteristics of electron spin resonance (ESR) dosimetry using bovine bone samples are described. The number of paramagnetic centers created by gamma radiation in the inorganic bone matrix was measured as a function of absorbed dose. The minimum detectable dose was 0.5 Gy for 60Co gamma rays. The response was linear up to the maximum dose studied (30 Gy) and independent of dose rate up to the maximum dose rate used (1.67 Gy min-1). For different bone samples the reproducibility was 5%. This method may be valuable for nuclear accident dosimetry.     

Sterilization of Bacillus thuringiensis israelensis products by gamma radiation

This study examines the effect of routine gamma radiation based on cobalt 60 on the viability, mosquito larvicidal activity, and density of bacillus spores in the soil. Although 1 g of unirradiated powder of Bacillus thuringiensis israelensis (Bti) contains on average 6.2 x 10(9) spores, no spores survived radiation doses of 20.6 kGy and higher. Radiation at a dose of 20-25 kGy caused a 20-30% reduction in the effectiveness of Bti powder against mosquito larvae. In areas treated with unirradiated Bti material on average twice a year, soil contained 700,000 to 44 million spores per gram. In areas treated with irradiated Bti products, either no Bti spores or fewer than 100,000 were found per gram of soil. A radiation dose of 25 kGy fulfills the requirements of killing all spores in a Bti product and maintaining the effectiveness of the product in routine treatments. No viable spores remain in water used for household purposes or irrigation of garden areas when irradiated Bti fizzy tablets are used in water containers. Irradiation of Bti products fulfills the requirements of drinking water regulations and thus allows these products to be used widely.     

Influence of ionizing radiation and conventional food processing treatments on the status of free radicals in lotus seeds: An ESR study

Electron spin resonance (ESR) spectroscopy was used to detect the free radicals that were naturally present in lotus seeds or that were formed after employing various food processing methods (e.g., irradiation, microwave roasting, pan frying, grinding or pounding) by placing small portions of lotus seed (seed coat and cotyledon) in KCl powder in ESR quartz tubes. Spectral analysis revealed the presence of an insignificant natural abundance of free radicals and showed a sharp and clear signal at g = 2.002, more prominent in seed coat. Exposure to gamma radiation (0–30 kGy, the recommended dose for quarantine purposes) resulted in a dose-dependent increase of signal intensity at g = 2.002 with the seed coat exhibiting the presence of a weak triplet (a_H = 3 mT) which can be used to authenticate irradiation treatments. Irradiated cotyledon at high doses (15 and 30 kGy) revealed significant reduction in ESR signals, attributed to an increase of free radical scavengers. Common food processing practices like microwave roasting, flame heating, grinding or pounding also generated free radicals. It is envisaged that results of the present study might be valuable for health conscious consumers who are interested in the status of free radicals in foodstuffs subjected to traditional or modern food-processing techniques.     

12C6+对小鼠肝组织中脂类过氧化和血清抗氧化活力的影响

目的研究12C6 重离子全身照射对小鼠肝组织中脂类过氧化和血清抗氧化活力的影响。方法采用硫代巴比妥酸法测定重离子6Gy辐照后各组肝组织中脂质过氧化值;采用电子自旋共振自旋捕集技术检测辐照后各组血清对羟基的清除率。结果12C6 重离子全身辐照后46、70、82h组肝组织中脂质过氧化值明显增加,与对照组相比差异有显著性(P<0.01),但未出现峰值;辐照后各组血清对羟基的清除率明显下降,其中82h组的清除率最低,辐照后各组与对照组相比差异有显著性(P<0.01)。结论12C6 重离子全身辐照能引起小鼠肝组织中脂类过氧化并能使血清抗氧化活力下降。     

Presence of stable coal radicals in autopsied coal miners' lungs and its possible correlation to coal workers' pneumoconiosis.

Stable coal radicals (SCRs) were detected by electron spin resonance (ESR) spectroscopy in the lung tissue of autopsied coal miners. The SCR concentrations were measured in the lung tissues from 98 coal miners with and without (a) coal workers' pneumoconiosis (CWP), (b) cancer, and (c) a history of cigarette smoking. Concentrations of SCRs were also determined in the lungs of nonminer controls. The SCR concentration was related to longer mining tenure, CWP disease severity, lung cancer, and cigarette smoking. The mean concentration of SCRs in the lung tissues of miners with 30 +/- 1.4 y of coal mining exposure was 5.3 +/- 1.3 x 10(17) spins/g versus controls who had a nondetectable level (less than 10(15) spins/g). An increase in disease severity was accompanied by a progressive increase in SCR concentration. A SCR concentration of 4.8 +/- 0.7 x 10(17) spins/g was found for simple CWP (with moderate coal macules) versus 7.8 +/- 4.6 spins/g lung tissue for complicated CWP (with progressive massive fibrosis). Significantly higher (i.e., 10 x 10(17] concentrations of SCR in the coal miners' lung tissues were associated with an exposure history in the anthracite regions of northeastern Pennsylvania. These results indicate a possible role for SCRs in the disease process. Furthermore, ESR appears to be an adequate methodology for the quantitation of coal dust retained in the lung and for distinguishing exposures to anthracite and/or bituminous coal.     

Properties of radicals formed by the irradiation of wool fibers

Wool fibers of different sample conditions were irradiated in different atmospheres by (60)Co gamma-rays and were studied by electron spin resonance method (ESR). It was found that a large percentage of the alpha-carbon radicals of polymer main chain were more long-lived radicals. The ESR measurements of irradiated cortex samples of the wool fibers proved that most radicals from the cortex were long-lived ones. Low water content (as low as 27.5%) in the reaction system did not greatly affect the radical formation, but higher water contents would reduce the radical concentrations dramatically and accelerate their decaying process. The results will be of help in property modification of wool products by radiation graft copolymerization.     

Improvement of shelf-life and microbiological quality of minimally processed refrigerated capsicum by gamma irradiation

Shelf-life, microbiological and chemical quality of minimally processed capsicum subjected to radiation doses of 1, 2 and 3 kGy followed by storage at 5 degrees C and 10 degrees C were evaluated. Irradiation at an optimal dose of 2 kGy reduced the initial bacterial population by 2-3 log cycles and eliminated the coliforms Listeria and Yersinia. Chemical analysis revealed that the initial contents of ascorbic acid (127.7 mg/100 g), carotenoid (110 microg/100 g) and chlorophyll (7.75 mg/g) were reduced marginally by 5-10% with increasing radiation dose. However, during subsequent storage, up to 4 weeks, the temperature-dependent losses in vitamin C and chlorophyll content of irradiated samples were less compared with non-irradiated samples. The total carotenoid content of capsicum irradiated and stored for up to 2 weeks at 10 degrees C showed a similar trend. Thus, gamma irradiation at 2 kGy was found to improve both the hygienic quality and shelf-life without affecting the nutritional quality of minimally processed capsicum.     

Medium-mediated bystander effects on HSG cells co-cultivated with cells irradiated by X-rays or a 290 MeV/u carbon beam

The mechanisms of medium-mediated bystander effects on cell survival and micronucleus (MN) induction were investigated by co-cultivating unirradiated HSG cells with cells irradiated by X-rays or 290 MeV/u carbon beams. It was found that the survival of the irradiated cells exponentially decreased along with the dose, and that the plating efficiency (PE) of the unirradiated recipient cells was obviously more enhanced than that of the control cells. Moreover, MN was induced in the unirradiated recipient cells and its yield had a maximum distribution corresponding to the donor dose, which was different from the linear-quadratic dose response of the yield of MN in the irradiated cells. The treatment of PTIO, a scavenger of nitric oxide (NO), decreased both PE and MN of the unirradiated recipient cells to control levels. Moreover, nitrite was detected in the co-culture medium, and its concentration was related to the donor dose. These results indicated that NO was involved in the above mentioned medium-mediated bystander effects. In addition, an equation was deduced to well fit the induction of MN of the unirradiated recipient cells.     

Presence of Stable Coal Radicals in Autopsied Coal Miners' Lungs and Its Possible Correlation to Coal Workers' Pneumoconiosis

Stable coal radicals (SCRs) were detected by electron spin resonance (ESR) spectroscopy in the lung tissue of autopsied coal miners. The SCR concentrations were measured in the lung tissues from 98 coal miners with and without (a) coal workers' pneumoconiosis (CWP), (b) cancer, and (c) a history of cigarette smoking. Concentrations of SCRs were also determined in the lungs of nonminer controls. The SCR concentration was related to longer mining tenure, CWP disease severity, lung cancer, and cigarette smoking. The mean concentration of SCRs in the lung tissues of miners with 30 ± 1.4 y of coal mining exposure was 5.3 ± 1.3 × 10¹⁷ spins/g versus controls who had a nondetectable level (< 10¹⁵ spins/g). An increase in disease severity was accompanied by a progressive increase in SCR concentration. A SCR concentration of 4.8 ± 0.7 × 10¹⁷ spins/g was found for simple CWP (with moderate coal macules) versus 7.8 ± 4.6 spins/g lung tissue for complicated CWP (with progressive massive fibrosis). Significantly higher (i.e., 10 × 10¹⁷) concentrations of SCR in the coal miners' lung tissues were associated with an exposure history in the anthracite regions of northeastern Pennsylvania. These results indicate a possible role for SCRs in the disease process. Furthermore, ESR appears to be an adequate methodology for the quantitation of coal dust retained in the lung and for distinguishing exposures to anthracite and/or bituminous coal.