Measurement of scatter factors for 4, 6, 10, and 23 MV x rays at scattering angles between 30 degrees and 135 degrees

NCRP Report No. 49, published in 1976, describes how to calculate the shielding for the medical use of x rays and gamma rays for energies up to 10 MV, including primary, scattered, and leakage radiation. However, in that report, data for scattered radiation for linear accelerators exist only for 6 MV, and leakage radiation is assumed, incorrectly, to be equivalent to primary radiation. Since the publication of that report, linear accelerators with energies up to 25 MV have been widely used in the radiation therapy community. Thus, there is a need to measure additional data for all energies in the range 4-25 MV. In this study, measurements were made of the "a" factor for 4, 6, 10, and 23 MV x rays at scattering angles between 30 degrees and 135 degrees. The results show that the 6 and 10 MV "a" factor data are consistent with published data, and the 23 MV data are also consistent with recently published data at 18 and 25 MV. The data show that, in general, the "a" factor decreases with energy; the exception is that 23 MV data show a sharp increase at low scattering angles, much greater than at other energies.     

Intraventricular haemorrhage in the preterm infant without hyaline membrane disease

The clinicopathological associations of 33 singleton infants who died with intraventricular haemorrhage (IVH) without hyaline membrane disease (HMD) ('IVH only') were compared with those of 39 infants who died with IVH+HMD over the same gestation range in order to determine what factors other than those related to HMD may contribute to the pathogenesis of IVH. The incidence of 'IVH only' was inversely related to gestational age in the Hammersmith birth population, whereas the incidence of IVH+HMD rose to a peak at 28-29 weeks' gestation. Infants with 'IVH only' lived longer on average than those with IVH+HMD despite a lower birthweight and shorter gestation. Infants who died in the first 12 hours from 'IVH only' had suffered severe birth asphyxia but in those who died later the main symptom was recurrent apnoea. Fewer infants with asphyxia but in those who died later the main symptom was.recurrent apnoea. Fewer infants with 'IVH only' were given alkali therapy or were connected to the ventilator as compared to those with IVH+HMD, but there were no differences in alkali therapy in those who lived for 12 hours or more. In the 'IVH only' group there was a high incidence of haemorrhage from other sites and of bacterial infections. It is suggested that, in the absence of HMD, extreme immaturity is the main factor determining the occurrence of IVH. Birth asphyxia, apnoeic attacks, haemorrhage, and infections may play subsidiary roles, possibly through development of metabolic acidosis.     

Comparison of isometric and anatomical graft placement in synthetic ACL reconstructions: A pilot study

Correct graft placement is critical to the success of anterior cruciate ligament reconstructions (ACLR). Whilst current trend is to insert the graft in an anatomical location, synthetic grafts have shown to better perform when they are located in an isometric position. Placement, however, is largely dependent on the surgeon and no consensus has been reached for synthetic grafts.Kinematic flexion-extension data of four separate cadaveric knees was obtained using an optical tracking system. Knees were CT-scanned and computer models were developed for each specimen. Three different graft insertion techniques were simulated in each of the computer models. Kinematic data obtained from the optical tracking was applied to the 3D computer models to simulate knee flexion-extension, and virtual change in ACL graft length was measured over the cycle for each insertion technique. Length changes were plotted onto the Radiological-Quadrant.The isometric region on the femur was found to be a band spreading from the mid to deep end of the Blumensaat's line down to the shallow-inferior end of the femoral condyle. The JP Laboureau isometric point technique was consistently located in the isometric zone, with the following coordinates on the Radiographic-Quadrant: t=0.375 (SD 0.0066), h=0.227 (SD 0.0266). The Bernard–Hertel and Charlie Brown anatomical placement methods were located (13%, ?6%) and (8%, ?15%) away, from the JP Laboureau isometric point, respectively, based on t- and h- coordinates of the Radiographic-Quadrant.This study has determined the isometric region using three-dimensional analysis relative to the Radiographic-Quadrant. The JP Laboureau method best finds the isometric point. This information is useful for synthetic graft placement.     

Small interfering RNA inhibits SARS-CoV nucleocapsid gene expression in cultured cells and mouse muscles

SARS-CoV isa newly identified coronavirus that causes severe acute respiratory syndrome （SARS）. Currently, there is no effective method available for prophylaxis and treatment of SARS-CoVinfections. In the present study, the influence of small interfering RNA （siRNA） on SARS-CoV nucleocapsid （N） protein expression was detected in cultured cells and mouse muscles. Four siRNA expression cassettes driven by mouse U6 promoter targeting SARS-CoV N gene were prepared, and their inhibitory effects on expression of N and enhanced green fluorescence protein （EGFP） fusion protein were observed.     

带有蛋白转导结构域的bcr/abl癌蛋白片段表达及其跨膜转运

0　引言　人类免疫缺陷病毒 (human immunodeficiencyvirus,HIV) - 1编码的反式激活蛋白 TAT具有独特的跨膜运转方式 ,而且有转导速度快 ,效率高的特点 ,被称为蛋白转导结构域 (protein transduction domain,PTD) [1 ,2 ] .本研究用PCR扩增了慢性粒细胞白血病慢粒 bcr/ abl融合蛋白的基因片段 ,在其 5′端融合 PTD结构域的编码区后在大肠杆菌中进行了表达 .表达产物经纯化后 ,加入培养的 HL 6 0细胞 ,表达的蛋白可直接进入细胞内 .这一结果为用外源蛋白负载(L oading)免疫细胞提供了新的途径 .1　材料和方法1.1　 DNA重组　人工合…     

Low-artifact intravascular devices: MR imaging evaluation

Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection. GRE imaging allowed detection of intraluminal tilting of the percutaneous Greenfield and facsimile Amplatz (TMA-wire) filters. GRE imaging was useful for demonstrating postfilter turbulence due to clots, which was greatest for the Amplatz filter. Imaging of facsimile vascular devices made of tantalum or TMA wire did not cause the severe "black-hole" MR artifacts typical of the stainless-steel devices. SE and GRE imaging were very useful for determining caval patency in two patients with previously placed Mobin-Uddin filters. Noninvasive MR evaluation of blood vessels in the presence of a variety of low-artifact intravascular devices appears feasible.     

巫山淫羊藿的化学研究

从小檗科Berberidaceae淫羊藿属Epimedium植物巫山淫羊藿Epimedium wushanense T.S.Ying的地上部分中分得两种黄酮甙单体,经理化性质鉴定及紫外、红外、质谱、氢谱、碳谱等光谱分析,确定甙Ⅰ是新化合物,命名为巫山淫羊藿甙(wushanicariin)。甙Ⅱ是已知化合物淫羊藿甙(icariin),系首次从该种植物中分离。     

DSM melancholic features are unreliable predictors of ECT response: a CORE publication

OBJECTIVE: To determine the relationship between baseline melancholic features with outcomes in patients with major depressive disorder referred for electroconvulsive therapy (ECT). METHOD: In a multihospital (Consortium for Research in ECT) collaborative ECT study, SCID-1 interviews were obtained at study entry. Ratings of the 24-item Hamilton Rating Scale for Depression were obtained thrice weekly during the course of ECT, once during a subsequent treatment-free week, and periodically during 6-month continuation treatment with either bitemporal ECT or nortriptyline plus lithium (continuation pharmacotherapy). RESULTS: The evaluable sample was severely ill with a mean 24-item Hamilton Rating Scale for Depression score of 35.2 (+/-6.9). Of 489 patients, 63.6% (311) met DSM-IV criteria for melancholic features. During acute ECT, 62.1% of those with melancholic features remitted, as compared with 78.7% for those without melancholic features (P = 0.002). During medication continuation treatment (continuation pharmacotherapy), relapse rates were higher for those with melancholic features than for those without these features. Conversely, with continuation ECT, the rate of relapse was lower for those with, compared with those without, melancholic features. CONCLUSIONS: Ascertaining melancholic features by SCID-1 criteria does not identify depressed patients more likely to respond to ECT as had been anticipated from the literature. Melancholic features were associated with poorer treatment outcomes in acute ECT. Those with melancholic features were less likely to relapse with continuation ECT, but those with melancholic features were more likely to relapse with continuation pharmacotherapy. The limitations of the DSM-IV criteria for melancholia are discussed.     

Tolerance to p53 by A2.1-restricted Cytotoxic T Lymphocytes

Elevated levels of the p53 protein occur in ~50% of human malignancies, which makes it an excellent target for a broad-spectrum T cell immunotherapy of cancer. A major barrier to the design of p53-specific immunotherapeutics and vaccines, however, is the possibility that T cells may be tolerant of antigens derived from wild-type p53 due to its low level of expression in normal thymus and lymphohemopoetic cells. The combination of p53 deficient (p53^−/−) and p53^+/+ HLA-A2.1/K^b transgenic mice was used as a model to explore the possibility that A2.1restricted cytotoxic T lymphocytes (CTL) are functionally tolerant of self peptides derived from the wild-type p53 tumor suppressor protein. A2.1-restricted CTL specific for a naturally processed p53 self-epitope spanning residues 187-197 were completely aborted in p53^+/+ as opposed to p53^−/− transgenic mice. In contrast, CTL specific for a second self-epitope spanning residues 261-269 of the murine p53 sequence were detected in both p53^−/− and p53^+/+ A2.1/K^b transgenic mice. However, the avidity of the CTL effectors obtained from p53^+/+ mice was 10-fold lower than that obtained from p53^−/− mice, again suggesting elimination of CTL with high avidity for the A2.1-peptide complex. The circumvention of functional tolerance of high avidity CTL may therefore be a necessary prerequisite for optimizing immunotherapy against A2.1-restricted wild-type p53 epitopes in humans.