Influence of rapidly successive head impacts on brain strain in the vicinity of bridging veins

Acute subdural hematoma due to a bridging vein rupture is a devastating but rare injury. There has to date been no satisfactory biomechanical explanation for this infrequent but costly injury. We surmise that it may be associated with multiple head impacts. Though numerical models have been used to estimate vein strains in single impact events, none to date have examined the influence on localized brain strain of rapidly consecutive impacts. Using the Simulated Injury Monitor, we investigated the hypothesis that such double impacts can increase strain beyond that created by any single impact. Input to our parametric study comprised hypothetical biphasic rotational head accelerations producing a maximum angular velocity of 40 rad./s. In each of 19 simulations, two identical angular inputs are applied at right angles to each other but with time separations varying from 0 to 40 ms. For these double impacts, it has been generally found that strain in the region of the bridging veins is different, than what would be associated with any corresponding single impact. In some cases, the effect is to actually reduce the tissue strain. In others, the strain in the region of the bridging veins is increased markedly. The mechanistic explanation for the strain increase is that the tissue strain from the first impact has not diminished fully when strain from the second impact is initiated. Rapidly consecutive impacts could be a potential mechanism leading to vein rupture that warrants further investigation.     

Modelling of intracranial behaviour on occiput impact in judo

Acute subdural hematoma (ASDH) sometimes occurred in judo because of the bridging veins’ failure by rotation of the brain in the skull. However, the relationship between intracranial behaviour and the motion of the body on occiput impact has not yet been clarified. In this study, we developed an intracranial mechanical model based on multibody dynamics and compared it with experimental results. The results show the importance of modelling bridging veins and cerebral spinal fluid to the relative displacement between brain and skull. The proposed model will contribute to accident analyses or the optimum design of supporting devices.     

Insensitivity of tensile failure properties of human bridging veins to strain rate: implications in biomechanics of subdural hematoma

The effects of strain rate on tensile failure properties of human parasagittal bridging veins were studied in eight unembalmed cadavers. While bathed in physiological saline at 37 degrees C, the intact vessel was stretched axially by a servo-controlled hydraulic testing machine at either a low strain rate of 0.1-2.5 s-1 or a high rate of 100-250 s-1. The mean ultimate stretch ratios for low and high strain rates, respectively, were 1.51 +/- 0.24 (S.D. n = 29) and 1.55 +/- 0.15 (n = 34), and the ultimate stresses were 3.24 +/- 1.65 (n = 17) and 3.42 +/- 1.38 MPa (n = 20). Neither difference between strain rates was significant (p greater than 0.45). Thus, our results do not support the hypothesis that sensitivity of the ultimate strain of bridging veins to strain rate explains the acceleration tolerance data for subdural hematoma in primates [Gennarelli, R. A. and Thibault, L. E. (1982) Biomechanics of acute subdural hematoma. J. Trauma 22, 680-686].     

Fluid–structure interaction simulation of the brain–skull interface for acute subdural haematoma prediction

Traumatic brain injury is a leading cause of disability and mortality. Finite element-based head models are promising tools for enhanced head injury prediction, mitigation and prevention. The reliability of such models depends heavily on adequate representation of the brain–skull interaction. Nevertheless, the brain–skull interface has been largely simplified in previous three-dimensional head models without accounting for the fluid behaviour of the cerebrospinal fluid (CSF) and its mechanical interaction with the brain and skull. In this study, the brain–skull interface in a previously developed head model is modified as a fluid–structure interaction (FSI) approach, in which the CSF is treated on a moving mesh using an arbitrary Lagrangian–Eulerian multi-material formulation and the brain on a deformable mesh using a Lagrangian formulation. The modified model is validated against brain–skull relative displacement and intracranial pressure responses and subsequently imposed to an experimentally determined loading known to cause acute subdural haematoma (ASDH). Compared to the original model, the modified model achieves an improved validation performance in terms of brain–skull relative motion and is able to predict the occurrence of ASDH more accurately, indicating the superiority of the FSI approach for brain–skull interface modelling. The introduction of the FSI approach to represent the fluid behaviour of the CSF and its interaction with the brain and skull is crucial for more accurate head injury predictions.

     

Global/local head models to analyse cerebral blood vessel rupture leading to ASDH and SAH

Blunt and rotational head impacts due to vehicular collisions, falls and contact sports cause relative motion between the brain and skull. This increases the normal and shear stresses in the (skull/brain) interface region consisting of cerebrospinal fluid (CSF) and subarachnoid space (SAS) trabeculae. The relative motion between the brain and skull can explain many types of traumatic brain injuries (TBI) including acute subdural hematomas (ASDH) and subarachnoid hemorrhage (SAH) which is caused by the rupture of bridging veins that transverse from the deep brain tissue to the superficial meningeal coverings. The complicated geometry of the SAS trabeculae makes it impossible to model all the details of the region. Investigators have compromised this layer with solid elements, which may lead to inaccurate results. In this paper, the failure of the cerebral blood vessels due to the head impacts have been investigated. This is accomplished through a global/local modelling approach. Two global models, namely a global solid model (GSM) of the skull/brain and a global fluid model (GFM) of the SAS/CSF, were constructed and were validated. The global models were subjected to two sets of impact loads (head injury criterion, HIC = 740 and 1044). The relative displacements between the brain and skull were determined from GSM. The CSF equivalent fluid pressure due to the impact loads were determined by the GFM. To locally study the mechanism of the injury, the relative displacement between the brain and skull along with the equivalent fluid pressure were implemented into a new local solid model (LSM). The strains of the cerebral blood vessels were determined from LSM. These values were compared with their relevant experimental ultimate strain values. The results showed an agreement with the experimental values indicating that the second impact (HIC = 1044) was strong enough to lead to severe injury. The global/local approach provides a reliable tool to study the cerebral blood vessel ruptures leading to ASDH and/or SAH.     

脑血管畸形破裂出血的影响因素及受试者工作特征曲线预测价值分析

目的:探讨脑血管畸形破裂出血的影响因素,并进行受试者工作特征(ROC)曲线分析。方法:回顾性分析我院2015年6月至2018年1月收治的138例脑血管畸形患者的临床资料,根据患者是否并发破裂出血,将其分为出血组(n=76)和未出血组(n=62)。采用单因素和多因素Logistic回归分析法对两组患者的临床资料进行研究,并采用ROC曲线评价各影响因素对脑血管畸形破裂出血的预测价值。结果:两组患者在与畸形血管团位置关系、是否合并硬脑膜动静脉瘘、合并动脉瘤数目、合并动脉瘤大小、合并瘤样变、供血动脉位置、引流静脉方向以及畸形血管团大小方面差异具有统计学意义(P0.05)。多因素Logistic回归分析结果显示,引流静脉方向、畸形血管团大小以及合并动脉瘤数目是脑血管畸形破裂出血的独立危险因素(P0.05)。引流静脉方向的ROC曲线下面积为0.921,特异度和灵敏度分别为0.832和0.801,是三种影响因素中预测价值最高的,其次是合并动脉瘤数目和畸形血管团大小。结论:合并动脉瘤、引流静脉方向以及畸形动脉血管团大小是脑血管畸形破裂出血的重要危险因素,且对脑血管畸形破裂出血具有一定的预测价值,可为脑血管畸形破裂出血的预防诊治提供参考。     

The FP25K Acts as a Negative Factor for the Infectivity of AcMNPV Budded Virus

Baculoviruses generally produce two progeny phenotypes—the budded virus (BV) and the occlusion-derived virus (ODV)—and the intricate mechanisms that regulate the temporal synthesis of the two phenotypes are critical for the virus replication cycle, which are far from being clearly understood. FP25K was reported to be responsible for the regulation of BV/ODV, and the mutations within result in a decrease of normal ODVs formation and an increase of BVs production. In this study, we demonstrated that the increase of BV titer in an fp25k knockout recombinant (fp25k-negative) was a result of higher infectivity of BVs rather than an increased production of BVs. The constitution of the major structural proteins and genome of parental and fp25k-negative BVs were analyzed. The results showed that the integrity of the majority of DNA packaged into the fp25k-negative BVs was intact; i.e., the genomic DNA of fp25k-negative BV had better transformation and transfection efficiency than that of the parental virus, indicating more intact genomes in the virions. Although the analysis of proteins associated with BVs revealed that more envelope protein GP64 were incorporated into the fp25k-negative BVs, subsequent experiments suggested that overexpression of GP64 did not improve the titer of BVs. Thus, we conclude that the main reason for higher infectivity of BVs is due to better genome integrity, which benefits from the deletion of fp25k resulting in increased stability of the genome and produce a higher proportion of infectious BVs. FP25K acts as a negative factor for the infectivity of BV.     

Proteomic Analysis of Mamestra Brassicae Nucleopolyhedrovirus Progeny Virions from Two Different Hosts

Mamestra brassicae nucleopolyhedrovirus (MabrNPV) has a wide host range replication in more than one insect species. In this study, a sequenced MabrNPV strain, MabrNPV-CTa, was used to perform proteomic analysis of both BVs and ODVs derived from two infected hosts: Helicoverpa armigera and Spodoptera exigua. A total of 82 and 39 viral proteins were identified in ODVs and BVs, respectively. And totally, 23 and 76 host proteins were identified as virion-associated with ODVs and BVs, respectively. The host proteins incorporated into the virus particles were mainly involved in cytoskeleton, signaling, vesicle trafficking, chaperone and metabolic systems. Some host proteins, such as actin, cyclophilin A and heat shock protein 70 would be important for viral replication. Several host proteins involved in immune response were also identified in BV, and a C-type lectin protein was firstly found to be associated with BV and its family members have been demonstrated to be involved in entry process of other viruses. This study facilitated the annotation of baculovirus genome, and would help us to understand baculovirus virion structure. Furthermore, the identification of host proteins associated with virions produced in vivo would facilitate investigations on the involvement of intriguing host proteins in virus replication.     

叶脉结构与功能及其对叶片经济谱的影响

叶脉由贯穿于叶肉内部的维管组织及其外围机械组织构成,多样化的脉序及网络结构使叶脉系统发生变异和功能分化。该文综述了叶脉系统结构与功能的最新研究进展。通过聚焦叶脉分级系统的结构与功能及其在叶片经济谱(LES)中的重要性,解释叶脉性状与其它叶片功能性状之间的关系及机制。不同等级叶脉在机械支撑与水分运输方面存在功能分化,其中1–3级粗脉在维持叶片形状和叶表面积以及物理支撑方面发挥重要作用,有利于维持叶片最大受光面积;4级及以上细脉具有水分调节功能,它们与气孔相互协调,影响叶片水分运输、蒸腾散热和光合作用速率。叶片生长过程与叶脉发育的动态变化模式决定叶脉密度,并影响叶脉密度与叶片大小之间的关系:叶面积与粗脉密度呈显著负相关,与粗脉直径呈显著正相关,而与细脉密度无关。与叶脉性状相关的叶片经济谱框架模型预测,叶脉密度较高的叶片寿命短、比叶重较小,叶片最大碳同化速率、代谢速率以及资源获取策略潜力较高。     

Role of Soft Matter in the Sandwich Vein of Dragonfly Wing in Its Configuration and Aerodynamic Behaviors

The microstructure of the main longitudinal veins of the dragonfly wing and the aerodynamic behaviors of the wing were investigated in this paper.The microstructure of longitudinal vein presents two circumferential chitin layers and a protein-fiber soft layer.The dragonfly wing is corrugated due to the spatial arrangement of longitudinal veins.It was found that the corrugation angle could significantly influence the lift/drag ratio across a range of attack angles by the wind tunnel experiments.The results of the finite element analysis indicate that the protein soft layer of vein facilitates the change of the corrugation angle by allowing substantial relative twisting deformation between two neighboring veins,which is not possible in veins without a soft sandwich layer.     

Tetramer-guided analysis of TCR beta-chain usage reveals a large repertoire of melan-A-specific CD8+ T cells in melanoma patients

The assessment of the TCR repertoire expressed by tumor-specific CD8+ T lymphocytes has been hampered to date by the difficulty of targeting the analysis to lymphocytes directed against a single epitope. In the present study we have used fluorescent A2/Melan-A tetramers in conjunction with anti-CD8 and anti-TCR beta-chain variable (BV) mAbs to analyze by flow cytometry the BV segment usage by Melan-A-specific CD8+ T cells in tumor-infiltrated lymph nodes (TILN) and tumor-infiltrating lymphocytes (TIL) from A2 melanoma patients. Analysis of TILN populations revealed small proportions of A2/Melan-A tetramer+ cells expressing many different BV together with over-representation of A2/Melan-A tetramer+ cells expressing certain BVs. The BV usage by A2/Melan-A tetramer+ lymphocytes in TIL was more restricted than that in TILN. Moreover, the predominant BV segments were quite distinct in populations derived from different patients. A2/Melan-A tetramer+ cells expressing the dominant BVs found in TILN could also be found in the corresponding peptide-stimulated autologous PBMC, although A2/Melan-A tetramer+ lymphocytes expressing additional BVs were also identified. Together, these results suggest that a large and diverse repertoire of Melan-A-specific T cells using different BV TCR segments is available in A2 melanoma patients.     

改良曲张静脉点式剥除术治疗中老年下肢静脉曲张的临床疗效

目的:探究改良曲张静脉点式剥除术在治疗中老年下肢静脉曲张的临床疗效。方法:收集我院已确诊为下肢静脉曲张的中老年患者37例,分成实验组与对照组。对照组18例行传统曲张静脉点式剥除术,实验组19例行改良曲张静脉点式剥除术。对比两组患者手术后的下肢静脉曲张的治疗效果。结果:实验组有效率(94.7%)显著高于对照组(72.2%),差异具有统计学意义(P0.05);与对照组相比,实验组患者手术时间较短、术中出血量较少、下床活动时间较早,术后并发症总治愈率较高,复发率、术后并发症发生率较低,其差异均有统计学意义(P0.05)。结论:采用改良曲张静脉点式剥除术治疗中老年下肢静脉曲张的患者能够更彻底的剥除曲张额静脉,有效的改善患肢症状,明显降低复发率。     

128排CT对股骨头置换术后下肢深静脉血栓形成的诊断价值分析

摘要 目的：探讨与分析128排电子计算机断层扫描(Computed Tomography,CT)对股骨头置换术后下肢深静脉血栓形成的诊断价值。方法：2015年1月到2020年7月选择在本院诊治的股骨头置换术后疑似下肢静脉血栓形成患者78例作为研究对象,所有患者都给予128排CT检查,记录影像学特征并判断诊断价值,分析下肢深静脉血栓形成的影响因素。结果：在78例患者中,128排CT判断图像优69例,良9例,优良率为100.0 %。静脉造影判定为术后发生下肢深静脉血栓形成11例(DVT组),发生率为14.1 %,检出病变血管45支。二分类多因素Logistic回归分析显示术中出血量、手术时间、使用激素、年龄是导致股骨头置换术后下肢深静脉血栓形成的重要因素(P<0.05)。DVT组的血容量(cerebral blood volume,BV)与达峰时间(time to peak,TTP)值高于非DVT组(P<0.05),血流量(blood flow, BF)与平均通过时间(mean transit time,MTT)值低于非DVT组(P<0.05)。DVT组的血管狭窄评分低于非DVT组(P<0.05)。128排CT对股骨头置换术后下肢深静脉血栓形成的诊断敏感性与特异性为100.0 %和97.0 %。结论：术中出血量、手术时间、使用激素、年龄是导致股骨头置换术后下肢深静脉血栓形成的重要因素,128排CT能有效检出下肢深静脉血栓形成情况,具有方便、快捷、无创的特点,可为临床诊治提供可靠依据。     

Twist buckling of veins under torsional loading

Veins are often subjected to torsion and twisted veins can hinder and disrupt normal blood flow but their mechanical behavior under torsion is poorly understood. The objective of this study was to investigate the twist deformation and buckling behavior of veins under torsion. Twist buckling tests were performed on porcine internal jugular veins (IJVs) and human great saphenous veins (GSVs) at various axial stretch ratio and lumen pressure conditions to determine their critical buckling torques and critical buckling twist angles. The mechanical behavior under torsion was characterized using a two-fiber strain energy density function and the buckling behavior was then simulated using finite element analysis. Our results demonstrated that twist buckling occurred in all veins under excessive torque characterized by a sudden kink formation. The critical buckling torque increased significantly with increasing lumen pressure for both porcine IJV and human GSV. But lumen pressure and axial stretch had little effect on the critical twist angle. The human GSVs are stiffer than the porcine IJVs. Finite element simulations captured the buckling behavior for individual veins under simultaneous extension, inflation, and torsion with strong correlation between predicted critical buckling torques and experimental data (R² = 0.96). We conclude that veins can buckle under torsion loading and the lumen pressure significantly affects the critical buckling torque. These results improve our understanding of vein twist behavior and help identify key factors associated in the formation of twisted veins.     

Evaluation of SPATA1-associated markers for stallion fertility

Stallion fertility is an economically important trait because the use of artificial insemination is increasing in the horse industry and superior sires are used more intensely. Molecular genetic markers may be useful as early indicators for a stallion's fertility and genetic improvement programmes. The testis-specific SPATA1 protein is involved in shaping the sperm head during spermatogenesis. Thus, the spermatogenesis associated 1 ( SPATA1 ) gene was chosen as candidate for stallion fertility, and we analysed intragenic single nucleotide polymorphisms (SNPs) as genetic markers for the least square means (LSM) of the pregnancy rate per oestrus of stallions and breeding values (BV) for the paternal and embryonic component of the pregnancy rate per oestrus. We sequenced the cDNA of SPATA1 to verify the annotated mRNA sequence. One SPATA1 -associated intronic SNP ( BIEC2-968854 ) showed a significant association with the embryonic component of BVs of stallions for the pregnancy rate per oestrus. The embryonic component of BVs was positively associated with homozygous C/C stallions. Both the additive and dominance effects were significant with values of −5.8% ( P  = 0.01) and −6.4% ( P  = 0.02) for the embryonic component of BVs. For the same SNP, a suggestive association was found for the LSM of the pregnancy rate per oestrus of stallions. Heterozygous stallions had higher pregnancy rates per oestrus than homozygous stallions. The dominance effect was 4.1% with a nominal P -value of 0.02. The SNP BIEC2-968854 can change an SP1 binding site and thus we assume that gene regulation may be influenced through this intronic mutation. This is the first report on SPATA1 being associated with the pregnancy rate per oestrus for stallions.     

HearNPV在生长对数期与平台期宿主细胞中的复制差异分析

使用实时荧光定量PCR技术对HearNPV在生长对数期和平台期HzAM1细胞的复制差异进行分析。结果表明,HzAM1细胞生长对数期的倍增时间为22 h,生长对数期的细胞以S期细胞为主(48.6%),而平台期细胞中以G2/M期细胞为主(72.6%)。在这两种不同状态的细胞中,病毒的复制主要在感染后60 h内完成,在感染后14~20 h,病毒复制倍增时间分别为1.8 h和1.9 h,几乎没有差别。但是感染生长对数期细胞时,吸附侵入细胞内的BV数量、BV释放的数量、最终的病毒产量以及病毒表达的蛋白产量明显高于被病毒感染的生长平台期细胞。如生长对数期细胞内复制合成的病毒DNA总量的25%装配形成BV病毒粒子出芽释放到细胞外,而对于平台期细胞,病毒DNA仅有13%装配形成BV病毒粒子出芽释放到细胞外。病毒感染两种生长状态的细胞,病毒DNA均从感染后7~8 h开始复制,没有明显差别;而生长对数期细胞从被感染后18~20 h释放子代病毒BV,生长平台期细胞则在感染后22~25 h开始释放病毒BV。在感染后30~60 h,在生长对数期被感染的细胞释放BV的速度约为483 copies/cell/h,而平台期细胞约为100 copies/cell/h。最初吸附侵入到生长对数期细胞内的BV粒子数量明显多于侵入到生长平台期细胞内的BV数量。实验证实,生长对数期与平台期的细胞膜的流动性有很大差别,推测健康细胞表面有活性的病毒受体数量可能决定了侵入细胞内的BV的数量。     

超声定位穿静脉结扎对下肢静脉性溃疡术后愈合影响的临床研究

目的:观察下肢静脉性溃疡患者穿静脉功能不全情况,探讨超声定位下肢穿静脉结扎对下肢静脉性溃疡术后疗效的影响。方法:40例大隐静脉曲张患者随机分成两组:A组采用大隐静脉高位结扎、静脉腔内微波射频闭合术及超声定位穿静脉结扎治疗,B组采用大隐静脉高位结扎和静脉腔内微波射频闭合术治疗。观察两组患者治疗后静脉性溃疡的愈合时间、复发率及瓣膜功能不全穿静脉数量部位,并比较两组患者临床预后评分。结果:术前两组瓣膜功能不全穿静脉数量分别是47条和44条,两组比较差异无统计学意义(P=0.5520)。术后两组愈合时间分别是(7.5±4.389)周和(11.6±6.489)周,两组比较差异具有统计学意义(P=0.048)。两组临床预后评分分别为(2.3±0.6)分和(1.1±1.5)分,两组比较差异具有统计学意义(P=0.042)。结论:多普勒超声可有效检测定位瓣膜功能不全的下肢穿静脉,在超声定位下行大隐静脉高位结扎、静脉腔内微波射频闭合术联合穿静脉结扎治疗下肢静脉性溃疡的疗效优于穿静脉不结扎。     

A high accumulation of minerals in human internal jugular vein

To elucidate age-related changes of mineral contents in human veins, the relative contents (RCs) of elements in the human internal jugular veins, superior and inferior venae cavae, and femoral veins from 27 subjects ranging from 40 to 98 yr old were analyzed by inductively coupled plasma atomic emission spectrometry. The average RCs of calcium in the 27 specimens were the highest in the internal jugular vein, followed in descending order by the superior vena cava, femoral vein, and inferior vena cava. The RCs of calcium and phosphorus in the internal jugular veins started to increase after the age of 50 yr, became the highest in subjects in their 60s and thereafter decreased gradually. It is noted that such accumulations of minerals, similar to the internal jugular vein, were also found in the veins, such as the superior and inferior venae cavae, and femoral vein. Accumulation of minerals in the veins is different from that of arteries, which increase progressively by aging, but do not decrease.