Hormetic Effect of H2O2 in Saccharomyces cerevisiae: Involvement of TOR and Glutathione Reductase

In this study, we investigated the relationship between target of rapamycin (TOR) and H₂O₂-induced hormetic response in the budding yeast Saccharomyces cerevisiae grown on glucose or fructose. In general, our data suggest that: (1) hydrogen peroxide (H₂O₂) induces hormesis in a TOR-dependent manner; (2) the H₂O₂-induced hormetic dose–response in yeast depends on the type of carbohydrate in growth medium; (3) the concentration-dependent effect of H₂O₂ on yeast colony growth positively correlates with the activity of glutathione reductase that suggests the enzyme involvement in the H₂O₂-induced hormetic response; and (4) both TOR1 and TOR2 are involved in the reciprocal regulation of the activity of glucose-6-phosphate dehydrogenase and glyoxalase 1.     

Disruption of Aspergillus fumigatus biofilm by Streptococcus pneumoniae: Mycelial fragmentation by hydrogen peroxide

Biofilm is a complex structure consisting of microorganisms such as bacteria, fungi and an extracellular matrix (ECM). Biofilms are involved in most microbial infections and show persistent resistance to antibiotic treatment and immune response. Both Aspergillus fumigatus and Streptococcus pneumoniae are colonizers that can form biofilms in the respiratory tract. These pathogens have been simultaneously isolated from the same patient, but their interaction is poorly understood. We observed morphological changes in single- and mixed-species biofilms prepared for confocal laser scanning microscopy and scanning electron microscopy (SEM). Pneumococci suppressed the development of a fungal biofilm, and it even disrupted a preformed fungal biofilm. When a preformed fungal biofilm was treated with pneumococci, the mycelial network was fragmented, and only bacteria could develop. SEM revealed that the fragmented mycelium was further disrupted into fine filaments as treatment time progressed, and that the ECM of the preformed fungal biofilm had disappeared. The pneumococcal culture supernatant contained mycelial fragmentation activity that was heat-sensitive. The culture supernatant of a mutant pneumococcal strain deficient in pneumolysin (Δply) also exhibited the mycelial fragmentation activity. Enolase and lactate oxidase, which are involved in glycolysis and hydrogen peroxide production, were identified in the culture supernatant of the Δply mutant. Neither the wild type nor the mutant strain could fragment the mycelium in the presence of catalase. These data suggest that hydrogen peroxide could fragment the mycelium and would terminate the co-existence of A. fumigatus and S. pneumoniae in biofilm.     

汽水分离装置对过氧化氢低温等离子体灭菌的促进作用

目的观察汽水分离装置对不同型号过氧化氢低温等离子体灭菌器灭菌能力的促进效果。方法采用不锈钢和聚四氟乙烯管腔,内置染菌载体,采用定性灭菌试验,比较安装汽水分离装置前后,对两种细菌芽孢的灭菌效果。结果未安装汽水分离装置的3台过氧化氢低温等离子体灭菌器,单周期灭菌后,不能全部杀灭模拟管腔内的细菌芽孢;安装汽水分离装置后,灭菌合格率为100%。结论汽水分离装置可以显著提高过氧化氢低温等离子体灭菌器对管腔类器械的灭菌效果。     

脱细胞天然骨基质的制备及其移植免疫分析

背景：同种异体骨来源广泛，便于大量加工贮存，如能去除其免疫排斥反应用于骨支架修复骨缺损，将很好地解决骨源问题，但目前去除免疫排斥的方法不尽理想。 目的：为修复骨缺损寻找去除动物骨中的免疫排斥反应方法进而提供理想的骨支架材料。 方法：取大鼠股骨经低渗-脱细胞、过氧化氢处理基质制备天然脱细胞骨支架，再通过苏木素-伊红和甲苯胺蓝染色、扫描电镜与透射电镜观察、有机成分分析、洗脱剂残留量测定和移植免疫分析的方法评估处理效果。 结果与结论：组织学观察可见处理后的脱细胞骨基质中胶原纤维排列规则，骨陷窝空虚，未见细胞，纤维连接蛋白和层黏连蛋白多存留在骨陷窝周边部。扫描电镜观察见处理组骨基质板层连接疏松，板层之间出现大量孔隙；透射电镜见骨陷窝区已无高密度影；高效液相色谱仪检测TritonX-100在脱细胞骨基质中几无残留；淋巴细胞刺激实验表明新鲜骨引起的免疫排斥反应要明显强于脱细胞骨基质（p<0.01）。说明联合应用低渗-脱细胞和过氧化氢处理基质的方法去除免疫排斥反应较为理想，为进一步制备组织工程骨支架材料进行动物移植实验打下基础。     

KR深度漂白系统的临床效果评价

目的:评价KR深度漂白系统对困难漂白牙的疗效、安全性及稳定性。方法:随机抽选14例重度着色及困难漂白牙患者322颗牙,将其分为3组。A组:一般重度着色牙组(117颗);B组:氟斑牙组(69颗);C组:四环素牙组(136颗),进行KR产品深度漂白系统治疗,并分别于漂白前,漂白结束以及漂白结束后1、3、6个月对照比色,重复记录漂白脱色改变情况,同时记录漂白过程中牙齿牙龈过敏表现。结果:KR深度漂白对A组和B组有明显漂白效果,显效率分别为93.2%和88.4%;KR深度漂白对C1组亦有较明显漂白效果,其显效率为68.2%,有效率100%,但A组和B组漂白效果显著优于C1组(P<0.01),而KR深度漂白对C2组患牙漂白效果不明显。经过6个月观察各组漂白脱色效果均稳定。结论:KR深度漂白系统对治疗非四环素类重度着色牙有明显疗效且疗效安全稳定。对治疗四环素牙特别是重度四环素牙还需更长时间的对照实验观察。     

汽化过氧化氢应用于烧伤重症监护病房终末消毒的效果研究

目的运用汽化过氧化氢消毒法对烧伤重症监护病房进行终末消毒,比较不同消毒用量的消毒效果。方法选取某院灼伤整形科一间110 m3空病房作为试验场地。将枯草杆菌黑色变种芽孢菌片打开后放置于事先预定无遮隔的15个布点位置(距消毒机器0、1、2、3、4 m处,每处再分上、中、下3个平面),以及无盖无菌试管内15个布点(位置同前),每个位点无盖无菌试管内和无遮隔各放置一张过氧化氢指示胶带。根据病房的大小分别以8、12 g/m3计算过氧化氢用量。待消毒5 h后,观察化学指示胶带变色情况,菌片放入肉汤培养,培养后观察结果。应用SPSS 20.0统计软件进行数据分析。结果采用8 g/m3过氧化氢消毒时,峰值浓度为255.9 g,达到峰值浓度的时间为1 h 48 min;采用12 g/m3消毒时,峰值浓度为337.6 g,达到峰值浓度的时间为2 h 26 min。当两种消毒用量消毒时间达到8 h,病房内的浓度基本相同。无遮隔情况下,两种消毒用量化学指示胶带均变色;无盖无菌试管内的化学指示胶带不能完全变色。过氧化氢消毒用量分别为8、12 g/m3时,无遮隔的标本阳性率分别为6.67%和2.67%,差异无统计学意义(P0.05),且各位点不同消毒用量的消毒效果比较,差异均无统计学意义(均P0.05)。结论化学指示胶带变色在临床中可作为消毒效果的初步判断。使用汽化过氧化氢进行终末消毒时要尽可能地充分暴露需消毒的物品,根据实际情况确定消毒时间和消毒用量,病室内不同位点消毒效果基本相同。     

Technique and Practical Problems: Determination of Respiratory Gases by Paramagnetic Oxygen Analyser and Carbon Dioxide Catharometer

We report a marked shift in whole-blood glucose measurements when a widely available glucose analyser is used. We compared a conventional glucose dehydrogenase (GDHG) method after protein precipitation and a direct polarographic method in conjunction with immobilized glucose oxidase. The polarographic method gave mean whole blood glucose levels from 79% to 95% of those measured by the GDHG method. No such difference was found in either plasma or serum samples or in water-based control samples.

The stability of glucose in fluoride oxalate tubes appears to be poorer than is usually assumed. We observed a 5-10% decrease in whole-blood glucose concentrations during the first hour after sampling under routine conditions.     

The enigmatic physiological roles of AhpCF,Gpx, Npr and Kat in peroxide stress response of Enterococcus faecium

In this work, the physiological roles of the primary peroxide scavenging activities of Enterococcus faecium AUS0004 strain were analysed. This healthcare-associated pathogen harbours genes encoding putative NADH peroxidase (Npr), alkyl hydroperoxide reductase (AhpCF), glutathione peroxidase (Gpx) and manganese-dependent catalase (Mn-Kat). Gene expression analyses showed that npr and kat genes are especially and significantly induced in cells treated with hydrogen peroxide (H₂O₂) and cumene hydroperoxide (CuOOH), which suggested an important function of these enzymes to protect E. faecium against peroxide stress. Mutants affected in one or several predicted anti-oxidative activities mentioned above showed that neither the peroxidases nor the catalase are implicated in the defence against peroxide challenges. However, our investigations allowed us to show that Npr is responsible for the degradation of approximately 45% of metabolically derived H₂O₂ which avoids accumulation of the peroxide to lethal concentrations.     

Baicalin prevents the production of hydrogen peroxide and oxidative stress induced by Aβ aggregation in SH-SY5Y cells

Alzheimer's disease (AD) is a common form of neurodegenerative disease. Mounting evidence suggests that metal ions play a key role in the aggregation of amyloid β peptide (Aβ), which acts as a factor or cofactor in the etiopathogenesis of AD. Therefore, inhibition of Aβ aggregation emerges as a potential approach for the treatment of AD. We have found that baicalin can interact with copper directly and inhibits Aβ1–42 aggregation. In addition, baicalin protects SH-SY5Y cells from oxidative injuries induced by Aβ1–42 aggregation through decreasing H₂O₂ production that is normally formed as a deleterious by-product of beta amyloid aggregation and the formation of plaques. Taken together, these data indicate that baicalin may be a potential agent to inhibit Aβ aggregation and thereby delay, mitigate or modify the progression of neurodegenerative diseases such as AD.