Computational Study of Human Head Response to Primary Blast Waves of Five Levels from Three Directions

Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts.     

The metabolic flexibility of quiescent CSC: implications for chemotherapy resistance

Quiescence has been observed in stem cells (SCs), including adult SCs and cancer SCs (CSCs). Conventional chemotherapies mostly target proliferating cancer cells, while the quiescent state favors CSCs escape to chemotherapeutic drugs, leaving risks for tumor recurrence or metastasis. The tumor microenvironment (TME) provides various signals that maintain resident quiescent CSCs, protect them from immune surveillance, and facilitates their recurrence potential. Since the TME has the potential to support and initiate stem cell-like programs in cancer cells, targeting the TME components may prove to be a powerful modality for the treatment of chemotherapy resistance. In addition, an increasing number of studies have discovered that CSCs exhibit the potential of metabolic flexibility when metabolic substrates are limited, and display increased robustness in response to stress. Accompanied by chemotherapy that targets proliferative cancer cells, treatments that modulate CSC quiescence through the regulation of metabolic pathways also show promise. In this review, we focus on the roles of metabolic flexibility and the TME on CSCs quiescence and further discuss potential treatments of targeting CSCs and the TME to limit chemotherapy resistance.Subject terms: Cancer metabolism, Cancer microenvironment, Cancer stem cells     

金黄杆菌ZHDP1菌株基因组分析及其蛋白酶活性特征与产酶优化

【背景】蛋白酶活性研究对于理解金黄杆菌属（Chryseobacterium）菌株的生态角色、工业价值及潜在致病机理十分重要。【目的】分析一株细菌的新型基因组序列,以此推断其中潜在的蛋白酶基因,并对其蛋白酶活性进行验证与优化,为后续研究提供数据支撑。【方法】利用高通量测序技术对菌株基因组序列进行测定与组装,并利用单因素优化方法对菌株的蛋白酶作用条件与产酶条件进行优化。【结果】分离得到一株蛋白酶活性菌株,通过分子生物学手段鉴定为金黄杆菌属菌株,并命名为Chryseobacterium sp. ZHDP1。该菌株基因组大小为4 917 748 bp,GC含量为35.95%,平均核苷酸相似性和DNA-DNA杂交指数分别为91.39和47.8。该菌株基因组中发现超过20条蛋白酶基因,上清液中也检测到蛋白酶活性,其最适反应温度和pH值分别为50℃和7.0。Zn²⁺、Mn²⁺和Cr₂O₇^2-对蛋白酶活性有强烈抑制作用。ZHDP1菌株在培养温度35℃、培养时间35 h、接种量4%、碳源和氮源为...     

Identification of a NodD repressible gene adjacent to nodM in Rhizobium leguminosarum biovar viciae

The nodFEL and nodMNT operons in Rhizobium leguminosarum biovar viciae are transcribed in the same orientation and induced by NodD in response to flavonoids secreted by legumes. In the narrow intergenic region between nodFEL and nodMNT, we identified a small gene divergently transcribed from nodM to the 3' end of nodL. Unlike the promoters upstream of nodF and nodM, the promoter of this gene is constitutively expressed. It appeared that its promoter might partially overlap with that of nodM and its expression was repressed by nodD. A deletion mutation was made and proteins produced by the mutant were compared with those by wild-type using 2D gel electrophoresis. Several protein differences were identified suggesting that this small gene influences the expression or stability of these proteins. However, the mutant nodulated its host plant (pea) normally.     

Phage Display,Peptide Production and Biological Assessment of Key Sequence of TGF-β1

International Journal of Peptide Research and Therapeutics - To isolate key sequences of transforming growth factor-beta 1 (TGF-β1) from the phage display 12-mer peptide library, synthesize...     

野生大豆和烟草根尖细胞分化过程中的DNA动态和细胞图像分析

分别截取野生大豆根尖分生区、伸长区和成熟区细胞,用Ｈｏｅｃｈｓｔ３３２５８对ＤＮＡ进行专一染邑,通过计算机数字图象处理系统,采用灰度测量法原位测定根尖不同区的ＤＮＡ含量。同理取烟草根尖不同区细胞,用率尔根反应对ＤＮＡ进行专一染色,并由与扫描显微光度计相联的数字图象处理系统原位测定备区域中细胞的ＤＮＡ含量。发现从分生区到成熟区,细胞核ＤＮＡ含量呈递增趋势。分化的细胞中含量异常增高而不分裂,说明ＤＮＡ的动态变化与发育和分化存在着某种联系。细胞图象分析的结果表明三个区的细胞面积、最大径、最小径及形态因子也沿分生区到成熟区呈递增趋势。     

Purification,characterization, and gene cloning of two laccase isoenzymes (Lac1 and Lac2) from Trametes hirsuta MX2 and their potential in dye decolorization

In this study, two laccase isoenzymes (Lac1 and Lac2) from the culture supernatant of Trametes hirsuta MX2 were purified, and the genes (Lac1 and Lac2) coding the isoenzymes were cloned. Both Lac1 and Lac2 contained an open reading frame of 1563 bp with an identity of 79%. The two isoenzymes showed significant biochemical differences. The maximal activities of Lac1 and Lac2 were at pH 2.5 with 2-2′-azino-di-(3-ethylbenzthiazoline sulfonic acid) (ABTS), and the optimal temperatures for the activities of Lac1 and Lac2 were 60 and 50 °C, respectively. Lac1 exhibited excellent resistance to acidic conditions and retained 62.17% of its initial activity at pH 2.5 after a 72-h incubation. Lac2 was more thermostable than Lac1 with half-lives (t_1/2) of 9.58 and 3.12 h at 50 and 60 °C, respectively; the t_1/2 of Lac1 were only 4.19 and 0.88 h, respectively. Both Lac1 and Lac2 isoenzymes have a strong tolerance to Mg²⁺, Mn²⁺, Cu²⁺, and EDTA (50 mM). At a low concentration of 0.05 U mL^?1, the enzymes could decolorize towards Remazol Brilliant Blue R, Acid Red 1, Crystal Violet, and Neutral Red in the presence of ABTS. These unusual properties demonstrated that the two laccases have strong potential for specific industrial applications.

     

Wound Healing Activity of Phage-Sisplayed TGF-β1 Model Peptide in Streptozotocin-Induced Diabetic Rats

International Journal of Peptide Research and Therapeutics - To evaluate the effect of phage-displayed TGF-β1 model peptide on cutaneous wound healing in streptozotocin-induced diabetic rats....