Experimental validation tests of fast Fourier transform convolution and multigrid superposition algorithms for dose calculation in low-density media.

BACKGROUND AND PURPOSE: Modern conformal radiotherapy treatments require accurate dose calculation in any relevant clinical situation. One of these situations is the treatment of lung tumors, where irradiation has to be planned under challenging conditions for dose calculation. In this study we assess the errors in dose values predicted by fast Fourier transform convolution (FFTC) and multigrid superposition (MGS) algorithms implemented in a commercial treatment planning system (TPS). MATERIALS AND METHODS: FFTC and MGS algorithms were used in a FOCUS 3.0.0 (Computerized Medical Systems, USA) to calculate doses in treatment plans using photon beams of 6 and 25 MV nominal energy from a Saturne 43 linac (GE Medical Systems, USA). A 10x10-cm beam irradiating a mediastinum-lung and a thoracic wall-lung-thoracic wall modeled geometry was assessed. The calculated data were compared with measurements performed with radiographic films and ionization chamber. RESULTS: FFTC algorithm leads to an average deviation from ionometric dose measurements of over 10%. Discrepancies between measured and calculated beam fringe values (distance between 50 and 90% isodose lines) of up to 8 mm were observed. For MGS algorithm, all the points assessed in both geometries fulfilled the 3%-3 mm accuracy criteria and the average deviation of absolute dose was about 1%. A maximum of 3 mm deviation in the beam fringe for any depth was found and was within 2 mm beyond the buildup region. Deviations between ionometric and film measurements were within 3%. CONCLUSIONS: MGS algorithm assesses with reasonable accuracy dose distributions and absolute dose in inhomogeneous regions like the lung region. Therefore, and respecting the inhomogeneity dose calculation, the system could be used in routine clinical practice and in dose-escalation programs. This is not true in the case of FFTC algorithm which leads to errors greater than 10% in the absolute dose calculation and underestimates the beam fringe by up to 8 mm.     

羊红膻根的化学成分研究

从羊红膻(Pimpinella thellungiana Wolff.)根中分得四个化合物,经理化常数测定和光谱数据解析证明为棕榈酸(Ⅰ)、4-丙烯基苯酚(Ⅱ)、松酯酚(Ⅲ)和新化合物2-甲基-2-羟基-5-甲氧基苯并[d]氢化呋喃-3-酮(Ⅳ)。     

Association of Helicobacter pylori Infection with Gastric Adenocarcinoma

Gastric adenocarcinoma is the most prevalent cancer in South Korea, and Helicobacter pylori (H. pylori) infection is also common. This study was performed to examine the association between H. pylori infection and gastric cancer, taking into account various other factors. To investigate the association between gastric adenocarcinoma and H. pylori infection, determined by urease-positive reaction in the CLO test, a total of 175 paired specimens (175 tumor and 175 tissues adjacent to tumor) of stomach cancer patients and a total of 113 control specimens were obtained. The positive H. pylori infection rates were 78.9% (138/175) among the patients in specimens of tumor or tissues adjacent to the tumor and 41.6% (47/113) among controls in the CLO test. A positive correlation between H. pylori infection and gastric cancer was observed (age-adjusted odds ratio, 7.0; MH χ²=34.5 with P <0.0005). These data suggest that stomach cancer patients in Korea have high infection rates of H. pylori regardless of site specificity, and this infection might be causally associated with stomach cancer.     

头孢克肟片和胶囊在健康人体的生物等效性

目的 评价头孢克肟片剂、胶囊剂与参比制剂在健康人体内的药代动力 学及其生物等效性。方法用三交叉全排列组合设计,18名健康男性受试者 交叉单剂量口服试验药头孢克肟片、胶囊和对照药头孢克肟胶囊剂,用高效液 相色谱法测定其的血药浓度。结果受试制剂头孢克肟片、胶囊与对照药头孢 克肟胶囊的Cmax分别为:(1．64±0．45),(1．58±0．37)和(1．67±O．46)μg· mL-1;tmax分别为:(3．78±0．38),(3．75±0．34)和(3．86±0．28)h;AUC0-24分 别为:(13．58±3．78),(13．49±3．63)和(13．36±4．16)mg·h·L-1;AUC0-∞ 分别为:(14．49±3．94),(14．32±3．87)和(14．05±4．31)mg·h·L-1。经统 计学分析,3组间均无显著性差异(P>0．05)。结论3种制剂具有生物等效 性。     

Expression of a synapse-associated membrane protein, P84/SHPS-1, and its ligand, IAP/CD47, in mouse retina

P84 and integrin associated protein (IAP) are heterophilic binding partners that are expressed in the central nervous system in addition to a variety of other tissues. Both molecules are known to be involved in cell signaling in nonneural tissues. In the retina, both molecules are expressed prominently in plexiform layers, suggesting a possible association with synapses. Here, we examined the cellular expression and ultrastructural localization of the two molecules in the developing mouse retina. Both appeared to be expressed at one or both sides of synaptic sites, although the expression of IAP in the retina precedes that of P84. Examination of transgenic IAP-null retinae revealed a failure of P84 to become associated with synaptic sites, suggesting the interaction of P84 with IAP was necessary for P84's synaptic localization. These findings suggest that the signaling activities of P84 and IAP are localized to sites of synaptic contact in the retina. Thus this pair of synapse-associated molecules represents a bidirectional signaling system that could function to modify synaptic activity or possibly trophic interactions between central neurons.     

Effect of chronic alcohol consumption on plasma lipid, vitamins A, and E in Korean alcoholics

This human study was conducted to evaluate the effect of chronic alcohol consumption on plasma concentrations of lipid and the antioxidative system in 44 Korean alcoholics and 45 age-, sex-, and nationality-matched nonalcoholic subjects. Plasma triacylglycerols and atherogenic index were higher in alcoholics than in control subjects. Plasma total cholesterol was not different among groups, but plasma high-density lipoprotein cholesterol was lower in alcoholics. There were positive correlations between ethanol consumption and plasma lipid peroxide and atherogenic index in all subjects; there were negative correlations between ethanol consumption and plasma high-density lipoprotein cholesterol in all subjects. There were no significant differences between alcoholics and control subjects in plasma concentrations of α-tocopherol, although plasma α-tocopherol/lipid tended to be lower in alcoholics. Plasma retinol was lower in alcoholics. These results suggest that chronic ethanol consumption can contribute to increased risk for vascular diseases in Korean alcoholics.     

升学与就业——班主任的心得体会

在中职教育面临严峻的升学与就业压力面前，我们如何适应当前形势，教育学生正确对待升学与就业，最终提高升学率与就业率，这是我们需要研究的一个重要课题。     

小儿高脂血症危险因素的临床抽样调查

目的通过临床抽样调查，探讨与小儿高脂血症发病有关的危险因素，为小儿高脂血症的早期检测提供客观指标。 方法北京大学第一医院儿科等于2004年9月，调查并分析了962名北京市景山学校在校学生(5~19岁)的血脂浓度，其中采用酶法测定总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白(HDL C)及低密度脂蛋白(LDL C)等4项指标。采用坐高、腰围、上臂围、体重指数来反映身体肥胖程度，进一步分析了这些指标与血脂浓度的关系。 结果在962名学生中，共检出高脂血症患儿122例，总检出率为12.7%。高脂血症组的坐高、腰围、上臂围、体重指数4项指标明显高于正常组，2组间差异有显著性(P<0.05)；坐高、腰围、上臂围、体重指数等4项指标与甘油三酯均呈高度显著正相关(P<0.01)，与高密度脂蛋白均呈高度显著负相关(P<0.01)。 结论正常组与高脂血症组的坐高、腰围、上臂围、体重指数4项指标差异均有显著性；坐高、腰围、上臂围、体重指数均是影响甘油三酯和高密度脂蛋白浓度的危险因素。     

北京地区7~18岁青少年血脂现状调查

目的通过最新一轮的北京地区儿童青少年血脂调查，建立新的正常参考值。 方法于2004-09，随机选取7~18岁北京市中小学生共971人，均来自北京市区及郊区各县。根据年龄(每3岁为一年龄段)及性别分为8组(7~9岁男、女组；~12岁男、女组；~15岁男、女组；~18岁男、女组)，应用日立7060型全自动生化分析仪检测其空腹血浆总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL C)及低密度脂蛋白胆固醇(LDL C)浓度，分别取TC、LDL C第75百分位及第90百分位点作为临界高限及高胆固醇血症浓度，取TG第90百分位点作为高甘油三酯血症浓度，取HDL C第5百分位点作为低高密度脂蛋白浓度，建立北京地区儿童血脂参考值。 结果971名儿童的血浆脂蛋白含量值呈正偏态分布，7~9岁男女性别组间血脂4项浓度；~12岁性别组间TG含量女高于男，余3项无统计学差异；~15岁性别组间TC及LDL C含量女高于男，余2项无统计学差异；~18岁性别组间TC及HDL C女高于男，余2项无统计学差异。 结论通过对971名北京市中小学生的血脂调查，建立了北京地区不同年龄性别儿童青少年的血脂正常值，确立了临界高胆固醇和高胆固醇血症浓度、高甘油三酯血症浓度和低高密度脂蛋白浓度。     

Tissue microarray: an effective high-throughput method to study the placenta for clinical and research purposes.

OBJECTIVE: Tissue microarray (TMA) technology allows simultaneous examination of the expression of many molecular markers (protein, mRNA, DNA, etc.) with high-throughput. The application of this technology, to date, has been largely confined to the study of cancer. Placental pathology poses unique challenges because of the size of the organ, its complex anatomy, as well as its histological heterogeneity. The objective of this study was to assess the feasibility and efficiency of TMAs for immunohistochemistry and in situ hybridization of placental tissues. STUDY DESIGN: TMAs were constructed using an automated tissue arrayer. Standard 0.6-mm or 1-mm microarray needles were used. Villous parenchyma, basal plate, and chorioamniotic membranes were targeted in each block. Five mum-thick TMA sections underwent immunohistochemical analysis of both cytoplasmic and nuclear antigens using a panel of antibodies against a variety of cytoplasmic [cytokeratin-7, vascular endothelial growth factor (VEGF), and protein Z], membranous (endoglin), and nuclear (c-fos and c-jun) antigens. mRNA in situ hybridization for surfactant protein A (SP-A) and chromogenic in situ hybridization for the Y chromosome (DYZ1) were also performed. RESULTS: Validation of TMA immunoreactivity demonstrated comparable results with corresponding whole sections. When a two-tiered scoring system (positive/negative) was employed, there was agreement between two and three cores and whole tissue sections (kappa>0.7). When a three-tiered scoring system (negative, weak-positive, or strong-positive) was used, the data from three cores showed the highest agreement with whole tissue sections (kappa >0.7). In situ hybridization experiments for mRNA and DNA were also successful in that the signals were readily detectable. Successful transfer from the donor block to the recipient block differed according to the anatomical compartment. The transfer efficiency of villous parenchyma, basal plate, and chorioamniotic membranes were 96.9% (875/903), 76.7% (115/150), and 75.4% (224/297), respectively. CONCLUSION: TMA is a practical and effective tool for high-throughput molecular analysis of the human placenta. Duplicate and triplicate cores offer agreement with whole tissue sections for two-category distinction immunostaining. TMA also affords relevant results from in situ hybridization experiments for mRNA and DNA. The major advantages are the conservation of tissues and reagents, simultaneous comparison of molecular markers in different anatomical compartments of the placenta, and reduction of experimental error.