Four dimensional radiotherapy: a review of current technologies and modalities

Organ motion is a substantial concern in the treatment of thoracic tumours using radiotherapy. A number of technologies have evolved in order to address this concern in both the fields of CT imaging and radiation delivery. This review paper investigates the technologies which have been developed for the delivery of radiotherapy as well as the accuracy and workload implications of their use. Treatment techniques investigated include: breath hold, breath gating, robotic compensation and MLC manipulation. Each technique has its own advantages and drawbacks in regards to accuracy, treatment time, linac alterations and workload. Further, some treatment techniques have specific requirements for what kind of CT scans needs to be used in the planning process. This, along with the aforementioned considerations, could influence the decision as to implement some of these treatment techniques in the clinic.     

Estimation of the basic reproductive number (R0) for epidemic, highly pathogenic avian influenza subtype H5N1 spread

Three different methods were used for estimating the basic reproductive number (R0) from data on 110 outbreaks of highly pathogenic avian influenza (HPAI) subtype H5N1 that occurred in village poultry in Romania, 12 May to 6 June 2006. We assumed a village-level infectious period of 7 days. The methods applied were GIS-based identification of nearest infectious neighbour (based on either Euclidean or road distance), the method of epidemic doubling time, and a susceptible-infectious (SI) modelling approach. In general, the estimated basic reproductive numbers were consistent: 2.14, 1.95, 2.68 and 2.21, respectively. Although the true basic reproductive number in this epidemic is unknown, results suggest that the use of a range of methods might be useful for characterizing epidemics of infectious diseases. Once the basic reproductive number has been estimated, better control strategies and targeted surveillance programmes can be designed.     

西门子多叶光栅人工校准方法研究与实验

目的：确保多叶光栅（MLC）在放射治疗中的定位精度。方法：通过详细分析西门子Primus和Oncor加速器内置82片多叶光栅的结构组成和特点,利用现有配备的工具进行手工校准MLC。结果：定期校准MLC,减少了加速器出现联锁的机率,保证了患者治疗的顺利执行。结论：总结了一种通过手动方式校准多叶光栅的方法。该方法不需专用工具,易于操作,具有一定的可行性。     

以支持细胞为饲养层培养冻存后大鼠精原干细胞研究

目的：研究冻存的精原干细胞体外分离培养的生物学特性,为今后冻存精原干细胞的批量培养和长期利用提供依据。方法：取7～8d的sD雄性大鼠,分离睾丸组织,用两步酶消化法和差速时间贴壁法,分离精原干细胞和支持细胞。以二甲基亚砜（DMSO）作冷冻保护液,将分离到的精原干细胞放置于液氮中冻存;利用体外培养体系,进行支持细胞的培养和饲养层的制备;然后将复苏的精原干细胞接种到支持细胞饲养层上培养,并利用碱性磷酸酶鉴定精原干细胞。结果：用两步酶消化法和差速贴壁法能分离到纯度较高的精原干细胞和支持细胞,冻存的SSCs解冻后能在支持细胞饲养层上贴壁、生长、增殖,碱性磷酸酶活性鉴定呈阳性。结论：冻存后精原干细胞在体外支持细胞饲养层上呈集落样生长,并能长时间维持细胞集落形态及数目,可为体外研究药物或毒物干扰精原干细胞提供细胞模型。     

Mapping changes in the obesity stigma discourse through Obesity Canada: a content analysis

BackgroundStigmatization of persons living with obesity is an important public health issue. In 2015, Obesity Canada adopted person-first language in all internal documentation produced by the organization, and, from 2017, required all authors to use person-first language in abstract submissions to Obesity Canada hosted conferences. The impact of this intentional shift in strategic focus is not known. Therefore, the aim of this study was to conduct a content analysis of proceedings at conferences hosted by Obesity Canada to identify whether or how constructs related to weight bias and obesity stigma have changed over time.MethodsOf 1790 abstracts accepted to conferences between 2008–2019, we excluded 353 abstracts that featured animal or cellular models, leaving 1437 abstracts that were reviewed for the presence of five constructs of interest and if they changed over time: 1) use of person-first versus use of disease-first terminology, 2) incorporation of lived experience of obesity, 3) weight bias and stigma, 4) aggressive or alarmist framing and 5) obesity framed as a modifiable risk factor versus as a disease. We calculated and analyzed through linear regression: 1) the overall frequency of use of each construct over time as a proportion of the total number of abstracts reviewed, and 2) the ratio of abstracts where the construct appeared at least once based on the total number of abstracts.ResultsWe found a significant positive correlation between use of person-first language in abstracts and time (R2 = 0.51, p < 0.01 for frequency, R2 = 0.65, p < 0.05 for ratio) and a corresponding negative correlation for the use of disease-first terminology (R2 = 0.48, p = 0.01 for frequency, R2 = 0.75, p < 0.001 for ratio). There was a significant positive correlation between mentions of weight bias and time (R2 = 0.53 and 0.57, p < 0.01 for frequency and ratio respectively).ConclusionUse of person-first language and attention to weight bias increased, while disease-first terminology decreased in accepted abstracts over the past 11 years since Obesity Canada began hosting conferences and particularly since more explicit actions for expectations to use person-first language were put in place in 2015 and 2017.     

Adaptive protocols based on predictions from a mechanistic model of the effect of IL7 on CD4 counts

In human immunodeficiency virus–infected patients, antiretroviral therapy suppresses the viral replication, which is followed in most patients by a restoration of CD4+ T cells pool. For patients who fail to do so, repeated injections of exogenous interleukin 7 (IL7) are experimented. The IL7 is a cytokine that is involved in the T cell homeostasis and the INSPIRE study has shown that injections of IL7 induced a proliferation of CD4+ T cells. Phase I/II INSPIRE 2 and 3 studies have evaluated a protocol in which a first cycle of three IL7 injections is followed by a new cycle at each visit when the patient has less than 550 CD4 cells/μL. Restoration of the CD4 concentration has been demonstrated, but the long-term best adaptive protocol is yet to be determined. A mechanistic model of the evolution of CD4 after IL7 injections has been developed, which is based on a system of ordinary differential equations and includes random effects. Based on the estimation of this model, we use a Bayesian approach to forecast the dynamics of CD4 in new patients. We propose four prediction-based adaptive protocols of injections to minimize the time spent under 500 CD4 cells/μL for each patient, without increasing the number of injections received too much. We show that our protocols significantly reduce the time spent under 500 CD4 over a period of two years, without increasing the number of injections. These protocols have the potential to increase the efficiency of this therapy.     

2009-2012年四川省艾滋病疫情估计

目的估计四川省存活的艾滋病病毒感染者/患者人数。方法 2009-2012年,应用工作簿方法对15-49岁6类高危人群和低危人群存活的艾滋病病毒感染者/患者人数进行估计,同时对模型未能涵盖的既往暗娼及其配偶、输血/血制品使用者、母婴传播人群、50岁以上男男性行为者及其配偶4类人群存活的艾滋病病毒感染者/患者人数应用病例报告和专题调查等数据进行调整估计。结果四川省存活的艾滋病病毒感染者/患者估计人数从2009年的85 300人上升至2012年的110 400人,历年环比增长率分别为11.5%,9.1%,6.4%,增长速度趋缓;感染率从2009年的0.097%上升至2012年的0.137%;性传播居全省艾滋病传播途径的首位,其中同性性传播呈上升趋势,注射吸毒居次位,母婴传播构成逐年增高,献血构成稳定。结论多轮疫情估计的开展及完善有助于掌握全省的艾滋病真实疫情,工作簿方法是基层易于掌握,适用的疫情估计方法。     

大骨节病患者12号染色体7个STR位点基因频率分析

目的分析大骨节病患者、病区内对照人群和非病区外对照人群12号染色体上7个短串联重复序列（STR）位点的多态性。方法采用荧光标记基因扫描方法，对12号染色体上D12S1718、D12S1675、D12S358、D12S367、D12S1638、D12S1646和D12S1682位点在陕西省永寿县、榆林地区大骨节病区患者和病区内对照人群及咸阳地区非病区外对照人群中的多态性进行分析，计算相应人群中7个位点的基因频率、基因型频率，并对各组间基因频率进行X^2检验。结果D12S1718、D12S1675、D12S358、D12S367、D12S1638、D12S1646和D12S1682位点在大骨节病患者中分别检出4、7、7、8、5、5和7个等位基因，5、12、13、11、10、9和13个基因型；在病区内对照人群中分别检出4、9、7、6、6、6和8个等位基因，5、10、12、14、12、9和13个基因型；在非病区外对照人群中分别检出7、9、7、7、5、8和11个等位基因，9、16、17、16、12、15和20个基因型；各组间基因频率进行比较，在D12S367位点和D12S1638位点，患者与病区内对照（D12S367：P=0．034；D12S1638：P=0．041）及非病区外对照间（D12S367：P=0．029；D12S1638：P=0．028）均有显著性差异；在D12S1646位点，患者与病区内对照间无差异（P=0．446），但病区人群与非病区外对照间有差异（患者一非病区外对照：P=0．036；病区内对照一非病区外对照：P=0．039）。结论大骨节病患者12号染色体的7个STR位点中D12S367和D12S1638等位基因分布显著不同于病区与非病区正常人。     

Transmission and distribution of virus serotypes: African horse sickness in zebra.

The prevalence of African horse sickness (AHS) serotypes in zebra foals from the Kruger National Park, South Africa was examined for possible associations between serotypes and to estimate the basic reproduction number, R0. The distributions of serotypes between zebra were not independent in the 6- and 7-8-month-old age classes (P < 0.005). This does not necessarily imply biological interactions between serotypes, as heterogeneity in host-vector transmission rates can generate non-independent distributions of serotypes. Both age and month of capture were significant factors in the number of serotypes infecting each zebra (P < 0.0001). Pairwise, positive associations between non-cross-reacting serotypes were found in the 7-8-month-old class only. For AHS overall, estimates of R0 ranged from 31-68. Assuming serotypes are transmitted independently, estimates of R0 for individual serotypes ranged from 10 for serotype 1 to 23 for serotype 6. The wide range of estimates emphasizes the need for a better understanding of serotype transmission and interactions in AHS.     

Dosimetric impact of systematic MLC positional errors on step and shoot IMRT for prostate cancer: a planning study

The positional accuracy of multileaf collimators (MLC) is crucial in ensuring precise delivery of intensity-modulated radiotherapy (IMRT). The aim of this planning study was to investigate the dosimetric impact of systematic MLC positional errors on step and shoot IMRT of prostate cancer. A total of 12 perturbations of MLC leaf banks were introduced to six prostate IMRT treatment plans to simulate MLC systematic positional errors. Dose volume histograms (DVHs) were generated for the extraction of dose endpoint parameters. Plans were evaluated in terms of changes to the defined endpoint dose parameters, conformity index (CI) and healthy tissue avoidance (HTA) to planning target volume (PTV), rectum and bladder. Negative perturbations of MLC had been found to produce greater changes to endpoint dose parameters than positive perturbations of MLC (p < 0.01). Negative and positive asynchronised MLC perturbations of −1 mm resulted in median changes in D₉₅ of −1.2 and 0.9% respectively. Negative and positive synchronised MLC perturbations of 1 mm in one direction resulted in median changes in D₉₅ of −2.3 and 1.8% respectively. Doses to rectum were generally more sensitive to systematic MLC errors compared to bladder (p < 0.01). Negative and positive synchronised MLC perturbations of 1 mm in one direction resulted in median changes in endpoint dose parameters of rectum and bladder from 1.0 to 2.5%. Maximum reduction of −4.4 and −7.3% were recorded for conformity index (CI) and healthy tissue avoidance (HTA) respectively due to synchronised MLC perturbation of 1 mm. MLC errors resulted in dosimetric changes in IMRT plans for prostate.     

Multiple linear combination (MLC) regression tests for common variants adapted to linkage disequilibrium structure

By jointly analyzing multiple variants within a gene, instead of one at a time, gene‐based multiple regression can improve power, robustness, and interpretation in genetic association analysis. We investigate multiple linear combination (MLC) test statistics for analysis of common variants under realistic trait models with linkage disequilibrium (LD) based on HapMap Asian haplotypes. MLC is a directional test that exploits LD structure in a gene to construct clusters of closely correlated variants recoded such that the majority of pairwise correlations are positive. It combines variant effects within the same cluster linearly, and aggregates cluster‐specific effects in a quadratic sum of squares and cross‐products, producing a test statistic with reduced degrees of freedom (df) equal to the number of clusters. By simulation studies of 1000 genes from across the genome, we demonstrate that MLC is a well‐powered and robust choice among existing methods across a broad range of gene structures. Compared to minimum P‐value, variance‐component, and principal‐component methods, the mean power of MLC is never much lower than that of other methods, and can be higher, particularly with multiple causal variants. Moreover, the variation in gene‐specific MLC test size and power across 1000 genes is less than that of other methods, suggesting it is a complementary approach for discovery in genome‐wide analysis. The cluster construction of the MLC test statistics helps reveal within‐gene LD structure, allowing interpretation of clustered variants as haplotypic effects, while multiple regression helps to distinguish direct and indirect associations.     

Dengue and the risk of urban yellow fever reintroduction in São Paulo State,Brazil

OBJECTIVE: To propose a mathematical method for the estimation of the Basic Reproduction Number, R0, of urban yellow fever in a dengue-infested area. METHODS: The method is based on the assumption that, as the same vector (Aedes aegypti) causes both infections, all the quantities related to the mosquito, estimated from the initial phase of dengue epidemic, could be applied to yellow fever dynamics. It is demonstrated that R0 for yellow fever is, on average, 43% lower than that for dengue. This difference is due to the longer dengue viremia and its shorter extrinsic incubation period. RESULTS: In this study the analysis was expanded to the epidemiological situation of dengue in S o Paulo in the year 2001. The total number of dengue cases increased from 3,582 in 2000 to 51,348 in 2001. It was then calculated R0 for yellow fever for every city which have shown R0 of dengue greater than 1. It was also estimated the total number of unprotected people living in highly risky areas for urban yellow fever. CONCLUSIONS: Currently there is a great number of non-vaccinated people living in Aedes aegypti infested area in the state of S?o Paulo.     

慢性乙型肝炎病人外周血单个核细胞HBV感染后对其细胞免疫功能影响的研究

应用聚合酶链（PCR）方法检测慢性乙型肝炎（乙肝）病人外周血单个核细胞（PBMC）内乙肝病毒DNA（HBVDNA）。54例PBMC内HBVDNA（＋）和71例PBMC内HBVDNA（－）病例平行测定自然杀伤细胞（NK）活性、T细胞亚群比值（CD4／CD8）和血清可溶性白细胞介素2受体（sIL－2R）。结果示慢性乙肝病人PBMC内HBVDNA（＋）组NK、CD4／CD8和sIL－2R与正常对照组及PBMC内HBVDNA（－）组病人相比差异均有非常显著性（P＜0．001）。同时发现慢性乙肝PBMC内HBVDNA（＋）病人NK活性、CD4／CD8比值和sIL－2R水平有直线相关性（P均＜0．01），而PBMC内HBVDNA（－）病人，仅CD4／Cd8比值和sIL—2R水平呈相关性（P＜0．001）NK活性尚未受到明显影响。结果表明，HBV感染PBMC导致慢性乙肝病人细胞免疫功能紊乱，有助于阐明慢性乙肝的发病机制，并有可能为乙肝的防治提供理论依据。     

siRNA体外合成体系中GMP浓度优化及其对HeLa细胞端粒酶抑制的研究

目的在小片段干扰RNA（short interfering RNA，siRNA）体外合成的反应体系中加入不同浓度的GMP，比较RNA转录效率的高低，探讨siRNA体外合成体系中GMP的最佳浓度。并以该法合成的siRNA对肿瘤细胞端粒酶基因表达进行RNA干扰来验证其干扰效应。为简便、高效、低成本体外合成制备siRNA提供优化的实验条件，为广泛开展RNA干扰实验打下基础。方法以本实验室根据端粒酶hTERT基因（genebankgi：2347128）2653—2673位的核酸序列，构建的末端带T7启动子的部分双链DNA为模板，用T7RNA聚合酶体外合成方法合成siRNA。在siRNA体外合成的反应体系中加入不同浓度的GMP，以分光光度法测定合成的RNA量来比较RNA转录效率的高低；从而确定siRNA体外合成中GMP的最佳浓度。并以磷酸钙共沉淀法将合成的siRNA转染Hela细胞。用TRAP-银染法和PCR—EIA分别检测siRNA转染后的Hela细胞端粒酶活性，以验证其干扰效应。结果在T7RNA聚合酶体外转录合成siRNA的反应体系中加入不同浓度的GMP，结果显示以GMP终浓度为5mM时的RNA转录效率为最佳。用该法合成的siRNA转染Hela细胞后端粒酶表达被抑制。结论GMP可提高T7RNA聚合酶体外转录体系的转录效率，本实验研究的反应体系中以5mM GMP终浓度为其最佳。以该优化法合成的针对端粒酶hTERT的siRNA对端粒酶的表达产生了干扰效应。     

HBV基因瞬时和稳定转染HepG2细胞的TLR4表达

目的 观察HBV基因瞬时和稳定转染HepG2细胞后表达TLR4的变化.方法 采用免疫荧光流式细胞术检测TLR4在肝癌细胞株HepG2和HepG2.2.15上表达的平均荧光强度(MFI)及阳性细胞率,将前期试验获得的HBV全基因组,采用脂质体瞬时转染肝癌细胞株HepG2,采用免疫荧光流式细胞术检测TLR4在细胞上表达的MFI及阳性细胞率,台盼蓝计数检测细胞增殖活性,并分析其与细胞表达TLR4的关系.结果 HepG2.2.15细胞上TLR4表达的MFI及阳性细胞率均明显高于HepG2(均为P'<0.01),HepG2细胞于转染HBV DNA各剂量组48h后TLR4表达的MFI和阳性细胞率与无HBV DNA脂质体转染对照组相比均显著升高(均P'<0.01),并且MFI和阳性细胞率与转染剂量均呈正相关(均P<0.01),与细胞存活数均呈负相关(均P<0.01).结论 瞬时和稳定转染HBV的HepG2细胞,都存在细胞TLR4的上调,这种上调伴随着细胞存活的减少,并可能参与了急慢性乙型肝炎的免疫损伤.     

HBV基因瞬时和稳定转染HepG2细胞的TLR4表达

目的 观察HBV基因瞬时和稳定转染HepG2细胞后表达TLR4的变化.方法 采用免疫荧光流式细胞术检测TLR4在肝癌细胞株HepG2和HepG2.2.15上表达的平均荧光强度(MFI)及阳性细胞率,将前期试验获得的HBV全基因组,采用脂质体瞬时转染肝癌细胞株HepG2,采用免疫荧光流式细胞术检测TLR4在细胞上表达的MFI及阳性细胞率,台盼蓝计数检测细胞增殖活性,并分析其与细胞表达TLR4的关系.结果 HepG2.2.15细胞上TLR4表达的MFI及阳性细胞率均明显高于HepG2(均为P'<0.01),HepG2细胞于转染HBV DNA各剂量组48h后TLR4表达的MFI和阳性细胞率与无HBV DNA脂质体转染对照组相比均显著升高(均P'<0.01),并且MFI和阳性细胞率与转染剂量均呈正相关(均P<0.01),与细胞存活数均呈负相关(均P<0.01).结论 瞬时和稳定转染HBV的HepG2细胞,都存在细胞TLR4的上调,这种上调伴随着细胞存活的减少,并可能参与了急慢性乙型肝炎的免疫损伤.     

维生素A缺乏对气管粘膜免疫的影响

目的探讨维生素A(VA)调节粘膜免疫的作用及其分子机制。方法建立维生素A缺乏(VAD)的大鼠模型,应用免疫组化、RT-荧光定量PCR和ELISA的方法,观察VA对气管粘膜树突状细胞数目(OX-62阳性细胞数)、成熟度(CD80、CCR7的阳性面积);抗原识别受体(TLR2和TLR4的阳性面积)和信号转导(MyD88的基因转录水平)及细胞因子产生的影响。结果VAD大鼠气管粘膜树突状细胞的数目显著增加,但成熟分化标志CD80和CCR7无明显变化。粘膜TLR2表达增强,MyD88mRNA水平上调。粘膜IL-12的表达升高,Th2细胞因子IL-4、IL-6的产生减少,IL-10的蛋白表达下调。结论VAD大鼠气管粘膜树突状细胞的数量、抗原识别受体水平和对细胞因子的调节都有显著变化,对树突状细胞的影响可能是VAD导致粘膜免疫功能下降的重要机制之一。     

HBV基因瞬时和稳定转染HepG2细胞的TLR4表达

目的 观察HBV基因瞬时和稳定转染HepG2细胞后表达TLR4的变化.方法 采用免疫荧光流式细胞术检测TLR4在肝癌细胞株HepG2和HepG2.2.15上表达的平均荧光强度(MFI)及阳性细胞率,将前期试验获得的HBV全基因组,采用脂质体瞬时转染肝癌细胞株HepG2,采用免疫荧光流式细胞术检测TLR4在细胞上表达的MFI及阳性细胞率,台盼蓝计数检测细胞增殖活性,并分析其与细胞表达TLR4的关系.结果 HepG2.2.15细胞上TLR4表达的MFI及阳性细胞率均明显高于HepG2(均为P'<0.01),HepG2细胞于转染HBV DNA各剂量组48h后TLR4表达的MFI和阳性细胞率与无HBV DNA脂质体转染对照组相比均显著升高(均P'<0.01),并且MFI和阳性细胞率与转染剂量均呈正相关(均P<0.01),与细胞存活数均呈负相关(均P<0.01).结论 瞬时和稳定转染HBV的HepG2细胞,都存在细胞TLR4的上调,这种上调伴随着细胞存活的减少,并可能参与了急慢性乙型肝炎的免疫损伤.