Just an additional hydrogen bond can dramatically reduce the catalytic activity of Bacillus subtilis lipase A I12T mutant: An integration of computational modeling and experimental analysis

Understanding the structural basis and energetic property of hydrogen bonding and its effects on enzymatic activity is fundamentally important for the rational design of specific enzymes with desired biological functions. In the current study, site-directed mutagenesis analysis preliminarily revealed that the amino acid substitution of Ile12 with Thr12 (I12T) dramatically reduced the hydrolytic activity of Bacillus subtilis lipase A. A further computational investigation proposed that the I12T mutation would establish a geometrically perfect hydrogen bond between the mutated Thr12 and catalytic Ser77 of lipase A, which considerably impaired the catalytic capability of lipase A through two distinct but complementary approaches: rigidizing the enzyme active site and lowering the nucleophilic ability of the catalytic residue Ser77. To verify this hypothesis, a homogenous mutation I12S serving as the control to the I12T mutation was created to examine the hydrogen bonding effect on enzymatic activity. It was found that the I12S mutant only suffered from a slight damage in its hydrolytic ability due to absence of the hydrogen bond originally present at the Thr12–Ser77 interface in the I12T mutant, which was further characterized systematically by quantum mechanics/molecular mechanics (QM/MM) modeling, atom-in-molecules (AIM) analysis and molecular dynamics (MD) simulation. It is suggested that the hydrogen bond arising from the I12T mutation in lipase A can considerably reduce the flexibility and mobility of the enzyme active site, thus impairing the catalytic activity of the lipase A I12T mutant remarkably; the activity loss can be, however, largely recovered by replacing Thr residue at the 12th position of I12T mutant with its analog Ser, which is chemically similar to Thr but cannot form effective hydrogen bonding with Ser77.     

局麻下经皮超低温冷冻隧道式肺穿刺活检同期消融手术68例分析

【摘要】 目的 探讨局麻下经皮超低温冷冻隧道式肺穿刺活检同期消融手术在临床中的应用价值。方法 回顾性分析2017年1月至2019年12月间,行CT引导下局麻经皮超低温冷冻隧道式肺穿刺活检同期消融手术68例患者的资料,分析穿刺成功率及并发症等指标。结果 穿刺成功率为100%,1例出现快速病理结果与常规病理结果的吻合度为100%。1例出现冷休克（1.5%）,2例出现肺不张（2.9%）,61例发生气胸（8.8%）,6例咯血（8.8%）,16例出现胸腔积液（23.5%）,无空气栓塞、肿瘤播散和种植转移等并发症发生。结论 局麻经皮超低温冷冻隧道式肺穿刺活检同期消融手术是一项创伤小、安全性高、准确率及灵敏度高的创新型肺组织穿刺活检消融技术,后续将进一步研究、验证此项新技术的优点。     

Long non-coding RNAs as potential biomarkers and therapeutic targets for gliomas

Gliomas are the most malignant and common primary brain tumors, accounting for 50–60%. Despite all surgical efforts in combination with intense chemoradiotherapy, gliomas still have a dismal prognosis. The early screening and identification of patients with gliomas could improve their prognosis by allowing proactive medical treatment. Traditionally, gliomas of varying subtypes and grades are diagnosed based on histopathological features, but this can be challenging, particularly in cases that lack the typical features. Molecular expression profiles using microarray analyses have provided additional information to help distinguish between glioma subtypes, which correlate well with histological profiles. Various molecular biomarkers and therapeutic targets for gliomas are currently available, including genes and miRNAs, but all remain in preclinical studies. Certain specific lncRNAs involved in gliomas have been identified in surgical brain biopsies, which may be involved in brain development and the pathogenesis of gliomas; these can also be detected in peripheral blood. Therefore, we postulate that these specific lncRNAs may be both potential biomarkers and therapeutic targets for gliomas.     

在百年学会的关怀下，临床解剖学健康成长

“东风露消息,万物有精神”。今年8月,将在北京召开,中国解剖学会百年庆典暨第36届学术年会,值此百年庆典来临之际,让我们了解一下在学会的关怀和关注下,走过坎坷不平道路的临床解剖学成长过程。1983年,学术期刊《临床应用解剖学杂志》创刊,为半年刊。办刊宗旨是为了加强解剖学基础理论研究与临床实践工作紧密结合。1984年,《临床应用解剖学杂志》由半年刊改为季刊。1988年,《临床应用解剖学杂志》更名为《中国临床解剖学杂志》。2002年,《中国临床解剖学杂志》由季刊改为双月刊。     

产前超声诊断先天性马蹄内翻足的应用价值

目的　探讨产前超声诊断先天性马蹄内翻足的应用价值。 方法　选取2016-2019年于我院就诊的38例（44只患足）先天性马蹄内翻足患儿作为观察组,筛查时间为孕周20～26周,另选取同期于我院检查正常的胎儿35例（70只足）作为对照组。应用彩色超声诊断仪分别测量2组足长(FL)及足宽(FW),并计算FL/FW值;采用Dimeglio法评估患儿病情严重程度,并分析其与FL、FW及FL/FW的相关性,采用ROC法分析FL、FW及FL/FW诊断先天性马蹄内翻足的临床价值。 结果　与对照组比较,观察组患儿FL及FL/FW值较小,而FW值较大,且均有统计学差异（P<0.05）;不同Dimeglio分级的FL、FW及FL/FW比较差异显著（P<0.05）,FL及FL/FW值随Dimeglio分级升高而逐渐减小（P<0.05）,而FW值随Dimeglio分级升高而逐渐增大（P<0.05）;Spearman分析显示,FW与 Dimeglio评分呈正相关,而FL和FL/FW与 Dimeglio评分呈负相关（P<0.05）;ROC分析显示,FL、FW及FL/FW诊断先天性马蹄内翻足的曲线下面积分别为0.723（95%CI：0.591～0.926,P =0.005）、0.661（95%CI：0.522~0.849,P =0.017）、0.835（95%CI：0.709~0.984,P<0.001）,最佳诊断截断值依次为4.01、2.49、1.92,诊断灵敏度和特异度分别为80.73和81.26、81.07和78.93、90.13和90.74,经分析,FL/FW对先天性马蹄内翻足的诊断价值最大。 结论　产前超声对临床准确诊断先天性马蹄内翻足具有重要参考价值。     

胸椎旁神经阻滞技术的研究进展

胸椎旁神经阻滞术(thoracic paravertebral block,TPVB)是将局麻药注入椎旁间隙进而产生同侧节段性躯体和交感神经阻滞的技术[1,2]。TPVB应用于脊柱、胸腹部急慢性疼痛的镇痛主要与胸椎旁间隙(thoracic paravertebral space,TPVS)的解剖结构有关。TPVS为位于胸椎两旁的楔形间隙,如图1所示[3],内含脂肪组织、脊神经根、肋间神经、胸神经背支、交通支、交感神经链和肋间动静脉等结构,其内侧界由椎体、椎间盘和椎间孔构成,向内经椎间孔与硬膜外间隙相连,外侧在肋横关节附近逐渐变细并延续为肋间隙。前缘为胸膜,后缘为肋横突上韧带,不同节段的上下边界由肋骨头、肋骨颈、横突以及肋横突韧带等分隔。关于TPVS的尾端边界有较大争议,部分学者认为腰大肌是TPVS的下边界[4],但其他研究发现注射剂可通过膈肌的内侧和外侧弧状韧带向腰丛和腹腔神经节扩散,并不存在尾端边界[5]。至今,还没有TPVS头端边界的相关描述。现将椎旁神经阻滞技术的种类、适应证和禁忌证、并发症等方面的研究综述如下。     

流道型轴流血泵支承结构设计与分析

目的:为了改善电磁轴承结构复杂、体积偏大,液力轴承承载力小、不能在较大负载下工作的弊端,提出一种流道型磁液悬浮轴流血泵,提高血泵承载能力。方法:流道型轴流血泵轴向采用永磁力进行支承,径向采用转子叶轮的流道结构产生的液力悬浮;利用Ansys对轴向瞬态磁场进行仿真,对磁力变化进行研究,利用Fluent对不同开槽方向、角度、深度的径向液力进行仿真,对液力变化进行研究。结果:根据轴向磁力随位移的变化,得出磁力最大为2.9 N,楔形开槽结构倾斜角为28°,开槽数为5,槽深0.36 mm,叶顶间隙为0.40 mm,性能达到最优,能满足人体使用。结论:流道型轴流血泵相对于普通磁液悬浮血泵有更高的承载力,较好的悬浮性能,为轴流血泵的优化研究提供了新的思路。     

Duration of SARS‐CoV‐2 RNA shedding and factors associated with prolonged viral shedding in patients with COVID‐19

To investigate the factors associated with the duration of severe acute respiratory syndrome coronavirus 2 RNA shedding in patients with coronavirus disease 2019 (COVID‐19). A retrospective cohort of COVID‐19 patients admitted to a designated hospital in Beijing was analyzed to study the factors affecting the duration of viral shedding. The median duration of viral shedding was 11 days (IQR, 8‐14.3 days) as measured from illness onset. Univariate regression analysis showed that disease severity, corticosteroid therapy, fever (temperature>38.5°C), and time from onset to hospitalization were associated with prolonged duration of viral shedding (P < .05). Multivariate regression analysis showed that fever (temperature>38.5°C) (OR, 5.1, 95%CI: 1.5‐18.1), corticosteroid therapy (OR, 6.3, 95%CI: 1.5‐27.8), and time from onset to hospitalization (OR, 1.8, 95%CI: 1.19‐2.7) were associated with increased odds of prolonged duration of viral shedding. Corticosteroid treatment, fever (temperature>38.5°C), and longer time from onset to hospitalization were associated with prolonged viral shedding in COVID‐19 patients.     

原发性骨外骨肉瘤十例临床病理学研究

目的探讨原发性骨外骨肉瘤(extraskeletal osteosarcoma,ESOS)的临床病理、免疫组织化学及分子病理学特征。方法收集2003年1月至2019年1月福建省立医院诊治的10例ESOS,进行HE、免疫组织化学染色及分子病理学检测,并电话随访及复习相关文献。结果3例女性和7例男性,年龄36~85岁(平均年龄60岁),肿块大小5.5~17.5 cm(平均11.0 cm)。低倍镜下,肿瘤呈结节状、片状、分叶状,肿瘤由梭形细胞、肿瘤性骨样组织、软骨样组织构成,三者比例多少不等,并相互移行,其中见异型性梭形细胞直接产生骨样组织。免疫表型:肿瘤细胞呈SATB2部分阳性(9/9),α-平滑肌肌动蛋白(4/10)和上皮细胞膜抗原(1/10)灶性阳性,Ki-67阳性指数10%~50%,结蛋白、CD68、S-100蛋白、SOX10、HMB45、CD117、DOG1、CD34、广谱细胞角蛋白(CKpan)、GATA3及PAX8均阴性。分子病理检测:未检测到MDM2/CDK4基因扩增信号(0/6);未见SSX18基因分离信号(0/5);未检测到C-KIT和PDGFR-α突变信号(0/3)。结论ESOS属于骨外成骨性肿瘤,诊断需临床、影像、病理学相结合,必要时免疫组织化学及分子病理检测辅助诊断。