Effects of mechanical strain on oxygen free radical system in bone marrow mesenchymal stem cells from children

Background

Physiological loading is widely believed to be beneficial in maintaining skeletal integrity by stimulating new bone formation through increases in osteoblastic activity and concomitant decreases in osteoclastic activity. However, excessive or nonphysiological loading is associated with bone injuries, including stress fractures and osteoporotic fractures, thereby leading to a decreased functional capacity of bone. It is known that the excessive generation of reactive oxygen species (ROS) is a significant factor underlying tissue injury observed in many disease states. The aim of this study was to study the effects of mechanical strain on oxygen free radical system [ROS, superoxide dismutase (SOD) and malondialdehyde (MDA)] in bone marrow mesenchymal stem cells (MSCs) from children.

Methods

To determine whether extreme levels of mechanical strain enhance ROS synthesis, we loaded cyclic tensile stretch of varying magnitude on MSCs. After MSCs were stimulated by mechanical strain, ROS labelled with 2,7-dichlorodihydrofluorescein (DCFH) fluorescent probe in cells were detected by flow cytometry (FCM) whilst SOD activity and MDA level were detected by xanthine oxidase method and thiobarbituric acid method, respectively.

Results

Extreme levels (>12%) of mechanical strain applied to children's MSCs enhanced ROS synthesis, decreased the activity of SOD and increased the level of MDA, in a time- and magnitude-dependent fashion.

Conclusions

These data suggest that excessive magnitude of cyclic tensile strain (>12%) could induce oxygen free radical disequilibrium, resulting in cytotoxicity. The findings may have clinical implications for orthopaedic practice.     

密闭式吸痰在ICU患者机械通气中的应用

目的探讨密闭式吸痰在ICU机械通气患者的应用方法与效果。方法将72例ICU机械通气患者随机分为实验组和对照组各36例,实验组运用密闭式吸痰管吸痰,对照组运用开放式吸痰管吸痰,对两组患者的效果进行比较。结果实验组吸痰前后HR、SpO2无明显变化,对照组吸痰后HR加快,SpO2明显下降;平均操作时间、痰液喷出情况实验组少于对照组,差异显著有统计学意义(p<0.05)。结论使用密闭式吸痰管吸痰可有效预防机械通气患者发生低氧血症、增加患者舒适度、减少交叉感染及减轻护士工作量。     

呼吸机联合肺表面活性物质治疗新生儿呼吸窘迫综合征的临床研究

目的探讨机械通气联合肺表面活性物质（固尔苏）治疗新生儿呼吸窘迫综合征（NRDS）的临床疗效。方法将72例确诊为NRDS患儿分为两组,对照组36例给予机械通气治疗,治疗组36例在机械通气治疗基础上加用固尔苏治疗。比较两组治疗后的血气分析结果及临床疗效。结果治疗组在用药1、12、24h后PaO2明显提高,PaCO2下降,pH上升,与对照组比较有显著差异（P〈0．05）。治疗组总有效率明显高于对照组（P〈0．05）。结论呼吸机联合肺表面活性物质能有效改善NRDS患儿肺通气、换气功能,临床疗效满意。     

Leptin administration affects growth and skeletal development in a rat intrauterine growth restriction model: preliminary study

Objective

Skeletal abnormalities are one of the hallmarks of growth delay during gestation. The aim of this study was to determine changes induced by leptin in skeletal growth and development in a rat model of intrauterine growth retardation (IUGR) and to elucidate the possible underlying mechanisms.

Methods

Intrauterine growth retardation was induced prepartum and the effects of leptin to mothers prenatally or to offspring postnatally were studied. Radii were harvested and tested mechanically and structurally. Tibias were evaluated for growth-plate morphometry.

Results

On day 40 postpartum, total bone length and mineral density and tibial growth-plate width and numbers of cells within its zones of offspring treated with leptin were significantly greater than in the control group.

Conclusion

Postnatal leptin administration in an IUGR model improves the structural properties and elongation rate of bone. These findings could pave the way to preventing some phenotypic presentations of IUGR.     

机械通气辅助治疗急性心肌梗死合并急性肺水肿的临床体会

目的探讨急性心肌梗死的患者在并发急性肺水肿时采取机械通气辅助治疗的效果。方法选择2008年1月～2010年12月收治的心肌梗死合并急性肺水肿的患者20例,对病情在常规治疗下不能缓解者应用机械通气的方法治疗。结果 20例患者中,成功抢救的患者为18例,占90%。心力衰竭症状在行机械通气治疗6h后呈明显缓解,心率减慢,动脉血PaO2、SaO2升高明显（P〈0.05）。结论急性心肌梗死合并急性肺水肿的患者采用机械通气辅助治疗可改善心功能,提高生命质量。     

经食管床弓上食管胃机械吻合在食管癌手术中的应用水

目的:探讨食管癌手术中使用弯管型吻合器经食管床行食管胃吻合的应用.方法:回顾性分析680例食管中、下段癌经左胸行食管癌切除,采用多次或一次性弯管型吻合器,经弓后食管床在主动脉弓上行食管胃吻合.结果:一次性吻合成功668例.吻合失败12例.死亡8例.随访570例(83.8％),随访时间(3 -84)个月.结论:胸中、下段...     

压力控制法肺复张在急性呼吸窘迫综合征中的应用

机械通气是急性呼吸窘迫综合征(ARDS)的主要治疗手段,肺复张手法应用较高压力开放塌陷肺泡,并使用高呼吸末正压防止肺泡塌陷,期望恢复肺泡的同一性,减少呼吸机相关性肺损伤,改善患者预后。但近年的临床试验却得出矛盾的结果,其有效性及安全性及具体实施方法仍无统一意见。现就压力控制法肺复张在ARDS中的有效性、安全性的操作方法予以综述。     

Mechanical,inflammatory, and embolic complications of myocardial infarction: An emergency medicine review

IntroductionDespite the declining incidence of coronary heart disease (CHD) in the United States, acute myocardial infarction (AMI) remains an important clinical entity, with many patients requiring emergency department (ED) management for mechanical, inflammatory, and embolic complications.ObjectiveThis narrative review provides an evidence-based summary of the current data for the emergency medicine evaluation and management of post myocardial infarction mechanical, inflammatory, and embolic complications.DiscussionWhile 30-day mortality rate after AMI has decreased in the past two decades, it remains significantly elevated at 7.8%, owing to a wide variety of subacute complications evolving over weeks. Mechanical complications such as ventricular free wall rupture, ventricular septal rupture, mitral valve regurgitation, and formation of left ventricular aneurysms carry significant morbidity. Additional complications include ischemic stroke, heart failure, renal failure, and cardiac dysrhythmias. This review provides several guiding principles for management of these complications. Understanding these complications and an approach to the management of various complications is essential to optimizing patient care.ConclusionsMechanical, inflammatory, and embolic complications of AMI can result in significant morbidity and mortality. Physicians must rapidly diagnose these conditions while evaluating for other diseases. In addition to understanding the natural progression of disease and performing a focused physical examination, an electrocardiogram and bedside echocardiogram provide quick, noninvasive determinations of the underlying pathophysiology. Management varies by presentation and etiology, but close consultation with cardiology and cardiac surgery is recommended.     

TiO2 nanotubes improve physico-mechanical properties of glass ionomer cement

ObjectivesThe aim of this study was to determine the physico-mechanical properties of a high viscosity glass ionomer cement (GIC) reinforced with TiO₂ nanotubes (TiO₂-nt).MethodsTiO₂-nt was incorporated into the GIC powder components (Ketac Molar EasyMix™) in concentrations of 0% (control group), 3%, 5%, 7% by weight. Compressive strength (n = 10/group), three point bending for flexural strength (n = 18/group), microshear bond strength to dentin and failure mode (n = 20/group), and surface roughness and weight loss before and after brushing simulation (30,000 cycles) (n = 8/group) were evaluated. Data were submitted to Shapiro-Wilk, ANOVA, Tukey and Chi-square tests (α ≤ 0.05).ResultsAddition of 5% of TiO₂-nt into GIC presented the highest values for compressive strength and differed from the control, 3% and 7% groups (p = 0.023). There were no significant differences in flexural strength (p = 0.107) and surface roughness before and after the dental brushing (p = 0.287) among the groups. GIC added with 5% TiO₂-nt showed the lowest weight loss values (p = 0.01), whereas the control, 3% or 5% TiO₂-nt groups presented similar microshear bond strength values (p ≥ 0.05). The 5% TiO₂-nt group featured higher microshear bond strength than the 7% TiO₂-nt group (p = 0.034). Cohesive in material was the most representative failure mode for all groups.SignificanceThe incorporation of TiO₂-nt did not affect GIC’s adhesiveness to dentin, but improved its compressive strength at 5%. Furthermore, TiO₂-nt decreased the percentage of weight loss after GIC’s surface wear.