Relationship between schistosomiasis and bladder cancer

Carcinoma of the urinary bladder is the most common malignancy in the Middle East and parts of Africa where schistosomiasis is a widespread problem. Much evidence supports the association between schistosomiasis and bladder cancer: this includes the geographical correlation between the two conditions, the distinctive patterns of gender and age at diagnosis, the clinicopathological identity of schistosome-associated bladder cancer, and extensive evidence in experimentally infected animals. Multiple factors have been suggested as causative agents in schistosome-associated bladder carcinogenesis. Of these, N-nitroso compounds appear to be of particular importance since they were found at high levels in the urine of patients with schistosomiasis-associated bladder cancer. Various strains of bacteria that can mediate nitrosation reactions leading to the formation of N-nitrosamines have been identified in the urine of subjects with schistosomiasis at higher intensities of infection than in normal subjects. In experimental schistosomiasis, the activities of carcinogen-metabolizing enzymes are increased soon after infection but are reduced again during the later chronic stages of the disease. Not only could this prolong the period of exposure to activated N-nitrosamines, but also inflammatory cells, stimulated as a result of the infection, may induce the endogenous synthesis of N-nitrosamines as well as generating oxygen radicals. Higher than normal levels of host cell DNA damage are therefore anticipated, and they have indeed been observed in the case of alkylation damage, together with an inefficiency in the capacity of relevant enzymes to repair this damaged DNA. In experimental schistosomiasis, it was also found that endogenous levels of host cell DNA damage were related to the intensity of infection. All of these factors could contribute to an increased risk of bladder cancer in patients with schistosomiasis, and in particular, the gene changes observed may have potential for use as biomarkers in the early detection of bladder cancer that may assist in alleviating the problem.     

The role of epidemiology in cancer prevention

1. ISA Brown and Shaver 288 pullets were changed from 8 h to 8, 10, 13 or 16 h photoperiods at 42, 63, 84, 105, 126 or 142 d of age. 2. Age at first egg (AFE) was curvilinearly affected by the size and timing of the change in photoperiod. AFE was advanced most by a photoperiod change from 8 to 13 h made at 63 or 84 d. ISA birds were generally more responsive than Shaver to the photoperiod changes. 3. Longer photoperiods significantly increased survivors' egg production, but decreased liveability to 504 d. so that eggs per hen housed were unaffected. Retarding AFE by 10 d reduced survivors' egg numbers by 7.0, but increased mean egg weight by 1.26 g. Egg output by Shaver birds was unaffected by AFE, but that of ISA was curvilinearly affected, with an apogee at an AFE of 135 d. In both breeds, egg weight and egg output were greater following an early or late, rather than a mid-term photostimulation. 4. Photoperiod significantly increased mean daily food intake during lay by 1.26 g/h. A 10 d retardation in AFE resulted in a reduction in food intake of 1 g/d. Efficiency of food conversion deteriorated according to the square of the photoperiod, and changed curvilinearly according to age at photostimulation. Food conversion efficiency improved by 0.05 g/g for each 10 d delay in AFE. 5. Shell quality was unaffected by AFE, but deteriorated with increasing photoperiod and was curvilinearly affected by age at photostimulation with the smallest shell weights associated with photostimulation at 63 d. The incidence of double-yolked (DY) egg production increased with photoperiod and decreased with delayed photostimulation. There was an exponential regression of DY eggs on AFE. 6. Body weight at first egg increased by 75 g/d delay in AFE, but body weight at 504 d of age was unaffected by AFE, photoperiod or age at photostimulation. Body weight gain during lay increased by 15 g/h increase in photoperiod, decreased by 6 g per 10 d delay in photostimulation and by 40 g per 10 d delay in AFE. Fat content at 504 d increased by about 10 g/kg and by 23 g/bird for each 10 d delay in AFE. 7. Mortality in lay increased by 0.8%/h increase in photoperiod, but was unaffected by either age at photostimulation or AFE.     

Root growth and phosphorus and potassium uptake by two corn genotypes in the field

In a field study P and K uptake by two corn (Zea mays L.) genotypes which differed in root growth was investigated. The effect of differences in root growth on P and K uptake was assessed using a mechanistic-mathematical model which describes nutrient uptake by growing plant roots in soil. Nitrogen was applied at 0 and 227 kg ha^–1 to Pioneer 3732 and B73xMo17 corn grown on Raub silt loam (fine-silty, mixed, mesic Aquic Argiudoll) and at 227 kg N ha^–1 to these two genotypes on Chalmers silt loam (finesilty, mixed, mesic, Typic Haplaquoll). Root growth and P and K uptake by the two corn genotypes was measured 31, 47, 75 and 91 d after planting on the Raub and 31, 47, 61 and 75 d after planting on the Chalmers soil.Root growth and P and K uptake by B73xMo17 was greater than that of Pioneer 3732 on N-fertilized Raub soil. On Chalmers soil the difference in root growth between the two genotypes resulted in an increase in K but not P uptake. The higher soil P level of the Chalmers appears to have offset possible differences in P uptake due to root size. There were no differences between the two genotypes in either the percentage of roots with root hairs, or the density or length of root hairs. Phosphorus and K uptake calculated with the simulation models for both corn genotypes on both soils over each of three growth periods agreed with observed P (Y = 0.68X + 1.71; r = 0.944^**) and K (Y = 0.88X + 15.52; r = 0.928^**) uptake. Differences in P and K uptake between B73xMo17 and Pioneer 3732 resulted primarily from the difference in root growth in the topsoil. A high correlation was found between root surface area and P (r = 0.893^**) and K (r = 0.928^**) uptake by both corn genotypes on both the soils.Journal paper No. 10,316 Purdue Univ. Agric. Exp. Stn., W. Lafayette, In 47906. Contribution from the Dep. of Agron. This paper was supported in part by a grant from the Tennessee Valley Authority.     

填埋场高密度聚乙烯膜缺陷渗漏试验及计算模型研究

因施工等原因造成土工膜渗漏十分常见,但渗漏量的计算是工程建设和运营面临的重大难题。本研究通过室内试验,测试了不同高密度聚乙烯(HDPE)膜厚度(w=0.5、1.0mm)、缺陷孔径(φ=3、5、10 mm)和膜上不同压力水头(h=0.3、0.5、0.65、0.8 m)时的缺陷渗漏量,并建立数学模型进行拟合。结果表明:相对于膜厚度而言,膜缺陷大小和压力水头高度对渗漏量的影响更大;渗漏量可表达为膜缺陷大小和水头高度的幂函数,但不同工况下的系数有别,因此实际工程应通过试验方式确定。     

环磷酸腺苷颗粒剂的制备

目的:优化从红枣中提取环磷酸腺苷(cAMP)的提取工艺,选择合适的辅料优化cAMP颗粒剂的成型工艺。方法:以cAMP的提取率为评价指标,对料液比、提取时间、乙醇体积分数、微波功率及微波处理时间采用响应面法进行优化,对可溶性淀粉、乳糖、糊精及其混合物的成型性、堆密度、休止角、溶化率及吸湿性等评价指标进行综合评分,选出合适的颗粒剂辅料,再以颗粒剂成型性为评价指标,通过正交实验设计选择最优的辅料比、乙醇体积分数及颗粒剂干燥温度,确定颗粒剂成型工艺并进行工艺验证。结果:cAMP提取工艺最优条件为:料液比1:15(g/mL),提取时间7.5 h,微波功率270 W,乙醇体积分数30%,微波处理时间10 min,在此条件下,cAMP提取率403.6 μg/g;颗粒剂最优辅料配比为浸膏:乳糖为1:4,乙醇体积分数为75%,干燥温度50℃。结论:此方法可行,重复性好,能制备出较好的颗粒剂,能有效的控制环磷酸腺苷颗粒的质量。     

QJ系列羊肚菌品种氨基酸特征评价

以自主选育的QJ系列羊肚菌品种为试验材料,通过检测子实体氨基酸组成及含量,明确氨基酸营养特征。使用联合国粮食及农业组织（Food and Agriculture Organization of the United Nations,FAO）/世界卫生组织（World Health Organization,WHO）标准模式谱、系统聚类分析和主成分分析等方法对氨基酸进行全面评价。结果表明,系列品种总体表现为氨基酸种类丰富、必需氨基酸种类齐全的基本特征。其中标准模式谱评价可知QJ-10、QJ-12 明显优于其他品种,QJ-9 是系列品种中必需氨基酸营养价值最高的品种。聚类分析将系列品种分为4 类,第一类为氨基酸总量高、呈味氨基酸丰富,包括QJ-3、QJ-6、QJ-8 和QJ-9。主成分分析结果表明,各品种氨基酸综合得分由高到低为QJ-6、QJ-8、QJ-9、QJ-12、QJ-3、QJ-7、QJ-10、QJ-2,其中QJ-6 羊肚菌综合得分最高,为0.38。该研究结果为进一步丰富QJ系列羊肚菌基础研究数据,为羊肚菌品种的差异化开发提供参考。     

我国保健食品的市场准入制度及对未来产品研发的启示和展望

近年来我国社会经济持续稳定发展,国民收入水平不断提升,随着居民健康意识不断增强,人们对保健食品的期待也越来越高.人们对能够提高自身免疫力等的保健功能产品越来越青睐,保健食品生产企业也应根据近几年更新较快的法规调整新产品的上市模式.目前我国对于保健食品的重要市场准入制度包括注册和备案,虽然2种制度在申报途径上不同,但注册...     

进口保健食品在我国注册备案情况及发展趋势

目的分析申请进口保健食品的\"瓶颈\"及原因,并提出进口保健食品未来的发展管理趋势。方法通过对我国上市的进口保健食品注册和备案产品总数、保健功能、原料及申请国家情况的统计分析,梳理进口保健食品注册备案法规,并对已获得注册和备案的进口保健食品建立数据库,通过excel软件进行描述性分类统计分析。结果根据进口注册的保健食品总量分析,2003年以前批准的产品占65%,2003年以后批准的产品占35%;注册产品保健功能以增强免疫力最多,其次为辅助降血脂,申报的保健功能涉及18个;申请备案的保健食品中保健功能以补充钙最多,其次是维生素D,申报的营养素涉及17个;进口保健食品注册和备案申请最多的是美国,涉及国家达到15个。结论面对巨大的国内消费市场,在我国获得注册批准证书和备案凭证的进口保健食品数量却不足一千个,远低于国外上市健康产品种类。这与我国对进口保健食品法规要求较严,国外保健食品类似产品管理不同等有关。作为进口到中国的保健食品,必须确保产品长期食用的安全性。未来随着保健食品原料目录的调整及法规完善,更多符合我国法律法规要求的进口保健食品将给国人带来更多的健康选择。