Systemic induction of volatile release in cotton: How specific is the signal to herbivory?

Plants attacked by herbivorous insects release chemical signals that attract natural enemies of the herbivores to the damaged plants. Feeding of Spodoptera exigua larvae on the lower leaves of cotton (Gossypium hirsutum L.) for multiple feeding periods of 9–12 h with a 12 h, interval in between when the caterpillars are removed overnight, will induce a systemic release of volatile compounds that is comparable to the volatiles released in response to continuous feeding damage on the lower leaves for several days. The systemic volatile release in response to herbivory can be mimicked by mechanically damaging the lower leaves and applying caterpillar oral secretion to the injured leaves over 4 days. Cotton plants that are only mechanically damaged systemically release significantly less -pinene, myrcene, (Z)-3-hexenyl acetate, (E)--farnesene and (E,E)--farnesene after 4 days compared to plants damaged mechanically with application of caterpillar regurgitant. However, multiple 9–12 h mechanical damage alone induces a significantly higher systemic release of (Z)-3-hexenyl acetate, myrcene, (E)--ocimene, and (E)--farnesene after 4 days compared to undamaged control plants. This indicates that multiple mechanical damage alone cannot mimic completely the response induced by mechanically injuring the leaves and applying caterpillar regurgitant. A specific elicitor in the regurgitant of the caterpillar enhances the amount of several systemically released volatiles. Thus, the systemic release of volatile compounds by herbivore-damaged cotton plants appears to be regulated by at least two different mechanisms.     

周期性张应力对面颌肌细胞Na~＋/K~＋-ATPase的影响

目的：研究周期性张应力对Na＋/K＋-ATPase功能活性及其表达的影响,明确Na＋/K＋-ATPase在功能矫形中面颌肌肉适应性改建的生物和分子机制。方法：构建面颌肌细胞体外培养-力学刺激模型;应用多通道细胞牵张应力加载系统,对面颌肌细胞施加不同时段的张应力刺激,测定Na＋/K＋-ATPase的功能活性;运用实时荧光定量PCR研究周期性张应力刺激对Na＋/K＋-ATPase功能亚基α亚单位mRNA的影响。结果：Na＋/K＋-ATPaseα1,α2亚单位随着加力时间延长,表达增强,同对照组比较,呈一致性上调（P〈0.001）;细胞加力1小时,α1的mRNA表达不受影响;加力2小时后,α1和α2的mRNA表达呈现逐渐增强趋势,48 h时达到最大值。张应力刺激对α2亚单位的mRNA表达似乎更为敏感,加力1 h时α2亚单位的mRNA表达水平即增加,增加量约为对照组的37.74%,具有显著的统计学意义。结论：周期性的机械牵张作用于培养的骨骼肌细胞,可诱导α1和α2亚单位mRNA的表达量增加;α1和α2亚单位对周期性张应力刺激的作用时间反应不同,α2亚单位的反应可能更为敏感。周期性张力刺激的增加所产生的压力可能是转录调节的主要因素;周期性张应力对骨骼肌细胞Na＋/K＋-ATPase水解亚的调节作用不同,可能在面颌肌肉对功能矫形力的适应性改建中具有重要作用。     

A combination of gamma irradiation and CaCl2 immersion for a pectin-based biodegradable film

Using citrus pectin a biodegradable film was prepared by a combination treatment of gamma irradiation (0, 10, 20, and 30 kGy) and CaCl₂ immersion (0, 5, and 10%) cross-linking. The tensile strength of the pectin-based film was the highest in the 5% CaCl₂ treatment at 20 kGy of an irradiation dose. The tensile strength of the film with CaCl₂ was generally higher than that of the non-CaCl₂ treatment. The elongation at break and water vapor permeability were the lowest at a CaCl₂ of 5% among the irradiated treatments. The total organic carbon content produced from the Paenibacillus polymyxa and Pseudomonas aeruginosa showed that the film of the 20 kGy-irradiated film was lower than those of the 0, 10, and 30 kGy-irradiated films. In conclusion, irradiation of the film casting solution at 20 kGy combined with a 5% CaCl₂ immersion resulted in film with improved mechanical properties and biodegradability.     

一种有效区分移植细胞和宿主细胞脑损伤模型的建立

为了区分移植神经细胞和宿主细胞,便于将来在宿主体内对移植细胞进行在体的电生理记录以及其它方面的研究,通过机械损毁的方法,建立了一种特殊的脑损伤模型。结果发现,通过机械损毁的方法,在大鼠大脑皮层形成形态规则的损伤空洞,其模型稳定,重复性好;在空洞内进行干细胞移植,能够长时间存活,移植神经干细胞绝大部分细胞分化为神经元,只有少量细胞分化为胶质细胞,而且移植细胞与宿主细胞分界明显;对移植细胞进行单细胞电生理记录,记录到神经元放电信号。这些结果表明,通过机械损毁的方法,在大鼠大脑皮层成功建立了一个稳定、精确定位移植细胞与宿主细胞界限的脑损伤模型。     

不同肠内营养液对老年重度AECOPD机械通气患者肠道屏障功能、免疫功能和炎症因子的影响

摘要 目的：探讨不同肠内营养液对老年重度慢性阻塞性肺疾病急性加重期（AECOPD）机械通气患者营养状况、肠道屏障功能、免疫功能和炎症因子的影响。方法：纳入2019年10月-2021年10月在我院住院治疗的老年重度AECOPD患者90例作为研究对象,采用密封信封法随机分为含膳食纤维肠内营养组（FEN组）及不含膳食纤维肠内营养组（NFEN组）各45例。两组患者均接受重度AECOPD规范治疗,并接受机械通气治疗。FEN组给予能全力进行营养支持治疗,NFEN组给予能全素进行营养支持治疗,两组患者均接受持续30 d的肠内营养。比较两组患者治疗前和治疗30 d后营养状况指标血清白蛋白（ALB）、前白蛋白（PA）、血红蛋白（Hb）,肠道屏障功能指标D-乳酸（DLA）、细菌内毒素（BE）、二胺氧化酶（DAO）,T淋巴细胞亚群（CD4⁺、CD8⁺、CD4⁺/CD8⁺）、体液免疫功能指标免疫球蛋白（Ig）G、IgM、IgA,炎症因子降钙素原（PCT）和白介素-6（IL-6）水平的变化,以及两组患者ICU住院天数、机械通气时间和并发症的差异。结果：治疗30 d后,FEN组ALB、PA和Hb水平均显著高于NFEN组（P<0.05）;FEN组DLA、BE和DAO水平均显著低于NFEN组（P<0.05）;FEN组CD4⁺、CD4⁺/CD8⁺以及IgG、IgA水平均显著高于NFEN组（P<0.05）;FEN组PCT、IL-6水平均显著低于NFEN组（P<0.05）。FEN组患者ICU住院天数、机械通气时间及并发症均显著少于NFEN组,差异有统计学意义（P<0.05）。结论：含膳食纤维肠内营养有利于改善老年重度AECOPD机械通气患者营养状况,修复肠道黏膜屏障功能,提高免疫功能,减轻炎症反应,从而改善预后,含膳食纤维的肠内营养支持治疗效果更佳。     

机械拉伸对骨髓间充质干细胞迁移行为的影响

目的:研究机械拉伸刺激对大鼠骨髓间充质干细胞迁移行为的影响并探讨其相关分子机制。方法:应用单轴机械拉伸加载装置考察不同条件的周期拉伸刺激对大鼠骨髓间充质干细胞迁移行为的影响,采用Transwell和划痕法评价细胞迁移能力,采用明胶酶谱法检测基质金属蛋白酶-2,-9(MMP-2,-9)表达的变化。结果:适宜的拉伸刺激可以明显促进大鼠骨髓间充质干细胞的迁移能力,1 Hz、10%应变拉伸8 h后可以使细胞迁移数量增加到对照组的1.58倍。拉伸刺激诱导骨髓间充质干细胞基质金属蛋白酶-2,-9(MMP-2,-9)表达。抑制剂GM6001抑制了拉伸诱导的MMP-2,-9分泌增加,同时抑制了拉伸刺激对细胞迁移的促进作用。结论:机械拉伸刺激影响大鼠骨髓间充质干细胞的迁移行为,MMP-2,-9在此过程中可能起着重要介导作用。     

Investigation into the structural, morphological, mechanical and thermal behaviour of bacterial cellulose after a two-step purification process

Bacterial cellulose (BC) is a natural hydrogel, which is produced by Acetobacter xylinum (recently renamed Gluconacetobacter xylinum) in culture and constitutes of a three-dimensional network of ribbon-shaped bundles of cellulose microfibrils. Here, a two-step purification process is presented that significantly improves the structural, mechanical, thermal and morphological behaviour of BC sheet processed from these hydrogels produced in static culture. Alkalisation of BC using a single-step treatment of 2.5 wt.% NaOH solution produced a twofold increase in Young's modulus of processed BC sheet over untreated BC sheet. Further enhancements are achieved after a second treatment with 2.5 wt.% NaOCl (bleaching). These treatments were carefully designed in order to prevent any polymorphic crystal transformation from cellulose I to cellulose II, which can be detrimental for the mechanical properties. Scanning electron microscopy and thermogravimetric analysis reveals that with increasing chemical treatment, morphological and thermal stability of the processed films are also improved.     

Polyvinyl alcohol cryogel based vessel mimicking material for modelling the progression of atherosclerosis

PurposeThe stiffness of Polyvinyl-alcohol cryogel can be adjusted through application of consecutive freeze-thaw cycles. This material has potential applications in the production of tissue mimicking phantoms in diagnostic ultrasound. The aim of this study was to use PVA-c to produce a range of geometrically and acoustically identical vessel phantoms modelling stages of atherosclerosis which could be verified through mechanical testing, thus allowing for more precision in quantitative in-vitro flow analysis of atherosclerosis.MethodsA series of anatomically realistic walled renal artery flow phantoms were constructed using PVA-c. In order to ensure precise modelling of atherosclerosis, a modified procedure of ISO27:2017 was used to compare the mechanical properties of PVA-c. Results were compared for the standard “dumbbell” test object and a modified vessel test object. The geometric accuracy and reproducibility of the vessel models were tested before and after implantation in flow phantoms.ResultsNo significant difference was found between the mechanical properties of the dumbbell test samples and the vessels for any number of freeze thaw cycles, with a correlation coefficient of R² = 0.9767 across the dataset, indicating that a direct comparison between the mechanical properties of the dumbbell test samples and the phantom vessels was established. The geometric reproducibility showed that before and after implantation there was no significant difference between individual vessel geometries (p = 0.337 & p = 0.176 respectively).ConclusionsPolyvinyl-alcohol cryogel is a useful material for the production of arterial flow phantoms. Care should be taken when using this material to ensure its mechanical properties have been correctly characterised. The guidelines of ISO37:2017 potentially provide the best procedure to ensure this.     

Preparation and characterization of persimmon leaves/cellulose blend fiber and comparison with cellulose fiber

With respect to the fact that persimmon leaves having better effects on medical area applications, a persimmon leaves/cellulose blend fiber was prepared by wet spinning from a DMSO/polyoxymethylene solvent under different spinning conditions, e.g. the temperature of coagulation bath, amount of persimmon leaves added and concentration of spinning solution. Based on mechanical measurement, X-ray diffraction and DSC characterization, it was found that this blend fiber had similar mechanical and thermal properties as referenced cellulose fiber obtained using the same method.     

A method for selective isolation and aggregation of epicuticular wax nanotubes in Picea pungens

A method for selectively isolating and aggregating intact nanotubes from leaf surfaces, in sample quantities useable for their characterisation in further experimental investigations, is presented here. It uses liquid sucrose, as a saturated solution, with its wetting behaviour modified by the addition of controlled amounts of ethanol, as a temporary entrapment and release medium, for removing nanotube material from the leaf surface, here of Picea pungens (Engelmann). This harvesting technique works by the slow, gentle transition of the medium from liquid to solid, capturing the nanotubes, and then back to liquid again, releasing them, to form an aggregate sample, with little compromise to the structural integrity of individual nanotubes. Scanning electron microscopy (SEM) images are presented rigorously illustrating the technique and its effectiveness. Comparison with other recent methods reveals its advantages, and potential applications are explored.