Elective Nodal Irradiation for Limited-stage Small-cell Lung Cancer: Survey of US Radiation Oncologists on Practice Patterns

BackgroundTraditionally, elective nodal irradiation (ENI) has been used in clinical trials that have established thoracic radiotherapy as instrumental in improving survival for patients with limited-stage small-cell lung cancer (LS-SCLC). However, several reports have suggested that the omission of ENI might be appropriate. Current US practice patterns are unknown regarding ENI for patients with LS-SCLC.Materials and MethodsWe surveyed US radiation oncologists via an institutional review board-approved questionnaire. The questions covered demographics, treatment recommendations, and self-assessed knowledge of key clinical trials. χ² and Cochran-Armitage tests were used to evaluate for statistically significant correlations between responses.ResultsWe received 309 responses. Of the respondents, 21% recommended ENI for N0 LS-SCLC, 29% for N1, and 30% for N2; 64% did not recommend ENI for any of these clinical scenarios. The respondents who recommended ENI were more likely to have been practicing for > 10 years (P < .001), more likely to be in private practice (P = .04), and less likely to be familiar with the ongoing Cancer and Leukemia Group B 30610 trial (P = .04). Almost all respondents (93%) prescribed the same radiation dose to the primary disease and involved lymph nodes. When delivering ENI, 36% prescribed the same dose to the involved and elective nodes, and 64% prescribed a lower dose to the elective nodes.ConclusionNearly two thirds of respondents did not recommend ENI, which represents a shift in practice. A recent large clinical trial that omitted ENI reported greater overall survival than previously reported and lower-than-expected radiation toxicities, lending further evidence that omitting ENI should be considered a standard treatment strategy.     

Association Between Clinical Tumor Burden and Efficacy of Immune Checkpoint Inhibitor Monotherapy for Advanced Non–Small-Cell Lung Cancer

BackgroundProgrammed cell death 1 (PD-1) inhibitors have become a standard treatment, albeit not completely effective, for patients with advanced non–small-cell lung cancer (NSCLC). Previous studies of advanced melanoma have revealed that the tumor burden predicted the response to PD-1 inhibitors, although this relationship has remained unclear for NSCLC.Patients and MethodsThe present single-center retrospective study evaluated 163 patients with advanced NSCLC who had received PD-1/programmed cell death ligand 1 (PD-L1) inhibitor monotherapy from December 2015 to December 2018. The clinical tumor burden was estimated using the baseline sum of the target lesions’ longest diameters (BSLDs), measured according to the Response Evaluation Criteria for Solid Tumors, and the baseline number of metastatic lesions (BNMLs).ResultsThe optimal cutoff values for predicting progression-free survival (PFS) were 5 for the BNMLs and 76 mm for the BSLDs, using the minimum P value method. The low-BNML group included 73 patients (44.8%). The median PFS was 12.2 months in the low-BNML group and 2.8 months in the high-BNML group (hazard ratio, 0.51; P = .0005). The low-BSLD group included 92 patients (56.4%). The median PFS was 9.6 months in the low-BSLD group and 3.4 months in the high-BSLD group (hazard ratio, 0.52; P = .0006). Multivariable analysis revealed that low-BSLD, low-BNML, nonsquamous histologic type and a PD-L1 tumor proportion score of ≥ 50% were independently associated with prolonged PFS.ConclusionsPD-L1 expression and the clinical tumor burden can predict the efficacy of PD-1/PD-L1 inhibitor monotherapy for NSCLC.     

生物安全柜的控制

生物安全柜是重要的一级屏障设备，适当的控制方式对生物安全柜的防护能力是很重要的。文中主要介绍了生物安全柜的控制要点和几种控制方式及其特点。     

An experimentally supported, mathematical explanation of the gas chromatographic elution behaviour of the long-chain carbon members of the homologous series

By substituting the saturated vapour phase tension of the pure normal hydrocarbons described by the Clausius-Clapeyron law into the accepted expression of the specific retention volume (V_g,T), a theoretically coherent and relatively simple mathematical evidence of the elution behaviour of the homologous members has been deduced. It gives exponential retention time dependence on carbon number for isothermal, and nearly equidistant (i.e., approximately linear retention-time dependence on carbon number) elution for linear temperature programmed gas chromatographic runs. The final equations are in close correlation with the experimental results. Special emphasis is placed on the fact that a good approximation—not strict physical laws—have been found.     

采用半透明效果实现医学三维整体可视化

目的通过改进直接体绘制技术（DVR）算法中的关键步骤，绘制能表达数据场中不同层次组织的内部结构。方法根据界面对光线的反射和物质本身对光线的衰减，将数据场划分为边界不丰富的简单数据场和边界丰富的复杂数据场，从而采用分段线性函数来构造阻光度传递函数（TF）；将数据场中低灰度体素点看为一种不发光但会导致采样光线衰减的物质；根据采样结束时采样光线的阻光度分布来调整TF，完成三维绘制。结果绘制出了不同层次组织的内部结构。结论本算法有效地解决了体素点相互遮挡的问题，实现了医学三维整体可视化。     

Measurement of kinetic parameters in skeletal muscle by magnetic resonance imaging with an intravascular agent.

The purpose of this work was to investigate the use of an intravascular contrast agent to determine perfusion kinetics in skeletal muscle. A two-compartment kinetic model was used to represent the flux of contrast agent between the intravascular space and extravascular extracellular space (EES). The relationship between the image signal-to-noise ratio (SNR) and errors in estimating permeability surface area product (Ktrans), interstitial volume (ve), and plasma volume (vp) for linear and nonlinear curve-fitting methods was estimated from Monte Carlo simulations. Similar results were obtained for both methods. For an image SNR of 60, the estimated errors in these parameters were 10%, 22%, and 17%, respectively. In vivo experiments were conducted in rabbits to examine physiological differences between these parameters in the soleus (SOL) and tibialis anterior (TA) muscles in the hind limb. Values for Ktrans were significantly higher in the SOL (3.2+/-0.9 vs. 2.0+/-0.5x10(-3) min-1), as were values for vp (3.4+/-0.8 vs. 2.1+/-0.7%). Differences in ve for the two muscles (8.7+/-2.2 vs. 8.5+/-1.6%) were not found to be significant. These results demonstrate that relevant physiological metrics can be calculated in skeletal muscle using MRI with an intravascular contrast agent.     

Caudate nucleus volume and cognitive performance: Are they related in childhood psychopathology?

BACKGROUND: Impaired neuropsychological test performance, especially on tests of executive function and attention, is often seen in children diagnosed with autism spectrum disorders (ASD). Structures involved in fronto-striatal circuitry, such as the caudate nucleus, may support these cognitive abilities. However, few studies have examined caudate volumes specifically in children with ASD, or correlated caudate volumes to cognitive ability. METHODS: Neuropsychological test scores and caudate volumes of children with ASD were compared to those of children with bipolar disorder (BD) and of typically developing (TD) children. The relationship between test performance and caudate volumes was analyzed. RESULTS: The ASD group displayed larger right and left caudate volumes, and modest executive deficits, compared to TD controls. While caudate volume inversely predicted performance on the Wisconsin Card Sorting Test in all participants, it differentially predicted performance on measures of attention across the ASD, BD and TD groups. CONCLUSIONS: Larger caudate volumes were related to impaired problem solving. On a test of attention, larger left caudate volumes predicted increased impulsivity and more omission errors in the ASD group as compared to the TD group, however smaller volume predicted poorer discriminant responding as compared to the BD group.