二维斑点追踪技术评价低温兔左室纵向功能

目的:探讨应用二维斑点追踪技术评价低温条件下兔左心室纵向功能的价值。方法:30只新西兰兔随机分成对照组(n=10),低温组A(n=10),低温组B(n=10)。先行常规心脏数据测量,然后采用组织多普勒(TDI),之后应用斑点追踪成像(STI)中的获取基底段、中间段、心尖段及整体水平SL、SrLs.SrL E,SrL A及分层应变技术获取3个长轴切面心内膜下、中层和心外膜下心肌收缩期纵向峰值应变(SL)。结果:①与对照组相比,A组心内膜下心肌LS值的减低,差异有统计学意义(P<0.05),B组3层心肌SL值的减低明显,差异有统计学意义(P<0.01)②与对照组相比,A组大部分纵向应变及应变率减低(P<0.05);B组基底段、中间段、心尖段及整体水平SL,SrL S、SrLE、SrLA均减低(P<0.01)结论:随低温时间延长,左室壁3层心肌SL值受累程度不同,心内膜应变较心外膜更加敏感,二维班点追踪技术比LVEF及TDI更早发现左室功能减低。     

Risk stratification in breast cancer screening: Cost-effectiveness and harm-benefit ratios for low-risk and high-risk women

In mammography screening programmes, women are screened according to a one-size-fits-all principle. Tailored screening, based on risk levels, may lead to a better balance of benefits and harms. With microsimulation modelling, we determined optimal mammography screening strategies for women at lower (relative risk [RR] 0.75) and higher (RR 1.8) than average risk of breast cancer, eligible for screening, using the incremental cost-effectiveness ratio (ICER) of current uniform screening in the Netherlands (biennial [B] 50-74) as a threshold ICER. Strategies varied by interval (annual [A], biennial, triennial [T]) and age range. The number of life-years gained (LYG), breast cancer deaths averted, overdiagnosed cases, false-positive mammograms, ICERs and harm-benefit ratios were calculated. Optimal risk-based screening scenarios, below the threshold ICER of €8883/LYG, were T50-71 (€7840/LYG) for low-risk and B40-74 (€6062/LYG) for high-risk women. T50-71 screening in low-risk women resulted in a 33% reduction in false-positive findings, a similar reduction in costs and improved harm-benefit ratios compared to the current screening schedule. B40-74 in high-risk women led to an increase in screening benefit, compared to current B50-74 screening, but a relatively higher increase in false-positive findings. In conclusion, optimal screening consisted of a longer interval and lower stopping age than current uniform screening for low-risk women, and a lower starting age for high-risk women. Extending the interval for women at lower risk from biennial to triennial screening reduced harms and costs while maintaining most of the screening benefit.     

Free Water Loss–induced Heterogeneous Residual Strain and Reduced Fatigue Resistance in Root Dentin: A 3-dimensional Digital Image Correlation Analysis

IntroductionThis study evaluated free water loss–induced residual strain with and without axial compressive loading and assessed the mechanical effect of cyclic loading in fully hydrated and partially dehydrated root dentin.MethodsRoot dentin sections prepared from freshly extracted human premolars were used. Customized 3-dimensional digital image correlation was used to qualitatively and quantitatively analyze the residual strain induced by 2 hours of free water loss in different regions of root dentin. Residual strain in partially dehydrated root dentin during axial compressive loading was also analyzed using 3-dimensional digital image correlation. The effect of cyclic loading on load to fracture in fully hydrated and partially dehydrated dentin and their fractography were analyzed using micro–computed tomographic imaging.ResultsFree water loss resulted in a heterogeneous distribution of residual strain and an overall formation of residual compressive strain with areas of tensile strain localized to the root canal and outer dentin. More residual compressive strain was observed in the apical dentin compared with the cervical dentin (P < .05), and more residual shear strain was observed in outer dentin compared with inner dentin (P < .05). Axial loading resulted in an increase in the load-induced compressive strain in the direction perpendicular to dentinal tubules (P < .05). Fully hydrated roots displayed a higher mean (P < .05) and median (P < .05) number of cycles to fracture with microcracks characteristic of toughness.ConclusionsAfter free water loss, root dentin displayed an increased formation of heterogenous residual strain, which resulted in increased axial compressive load-induced strain and a decreased resistance to fatigue failure. The effect of free water loss in the loss of mechanical integrity of root-filled teeth needs further investigation.     

急诊心肌梗死冠状动脉介入治疗术后患者T3水平与心肌再灌注的关系

目的探讨急性心肌梗死（AMI）患者急诊经皮冠状动脉介入治疗（PCI）术后血清三碘甲状腺原氨酸（T3）与心肌再灌注的关系。方法采用化学发光法检测205例AMI患者PCI术后血清T3水平，根据T3水平将患者分为A、B、C、D4组，记录并比较4组患者术后冠状动脉TIMI血流分级、心肌呈色分级（MBG）。结果A组（重度低T3组）TIMI3级比例低于B、C、D组，差异有统计学意义（P＜0.01）；MBG3级比例低于B、C、D组，差异有统计学意义（P＜0.01）。女性患者T3水平（1.00±0.05）nmol/L、TIMI3级比例（32/46，69.6%）、MBG3级比例（24/46，52.2%）均低于男性患者，后者分别为（1.19±0.02）nmol/L、（143/159，89.9%）、（110/159，69.2%），差异均有统计学意义（P＜0.05或0.01）。结论女性AMI患者心肌再灌注水平较男性患者低。AMI患者T3水平与PCI术后冠状动脉再灌注相关，监测T3可以间接反映病情的严重程度。     

High-magnitude mechanical strain inhibits the differentiation of bone-forming rat calvarial progenitor cells

Purpose: Orthodontic tooth movement occurs during the bone remodeling induced by therapeutic mechanical strain. It is important to investigate the relation between the strength of mechanical stress and bone formation activity. The aim of this study was to determine the effect of high-magnitude mechanical strain on bone formation in detail.

Materials and methods: Osteoblast-like cells isolated from fetal rat calvariae were loaded with 18% cyclic tension force (TF) for 48?h. To phenotypically investigate the effect of TF, we measured the number and the size of bone nodules stained by von Kossa technique on day 21 after cell seeding and determined the calcium content of bone nodules on day 14. Furthermore, we examined the gene expression of BMP-2, Runx2 and Msx2, which are important factors for bone nodule formation, on days 1, 4 and 7 after TF loading.

Results: The maximum bone nodule size in the control group was 1620 and 719?μm in the TF group. Furthermore, the mean number of bone nodules sized over 360?μm in the TF group was significantly decreased compared to the control group. The calcium content was also significantly decreased to 42% by TF loading. The mRNA expression of BMP-2, Runx2 and Msx2 was decreased 1 and 4 days after TF loading.

Conclusion: The differentiation of bone forming progenitor cells into bone nodule forming cells was inhibited by TF due to the decreased expression of bone formation related factors such as BMP-2, Runx2 and Msx2.     

缺血修饰性白蛋白在急性缺血性胸痛中的诊断价值

目的 评价缺血修饰性白蛋白（ischemia modified albumin，IMA）对急性缺血性胸痛（ICP）的早期诊断价值。方法 时206例发病〈12h、表现为急性胸痛的患者立即行12导联心电图（ECG）检查，并抽血进行IMA、肌钙蛋白I（cTnI）、肌酸激酶同工酶MB（CK-MB）测定。将ECG、IMA、cTnI、CK-MB的结果单独或结合与最终诊断为非缺血性胸痛（NICP）及ICP的相互关系进行比较。结果 最后诊断为ICP98例，NICP108例，ICP发病〈3h和3-6h组IMA水平明显升高，与NICP组比较差异有统计学意义（P〈0．001）；ICP发病〉6h组IMA水平与NICP组比较差异无统计学意义（P〉0．05）。IMA诊断发病〈3hICP的敏感性和阴性预测值（NPV）为89．1％和88．8％，明显高于ECG、cTnI和CK-MB，四者结合为97．6％和96．9％；IMA诊断发病3～6hICP的敏感性和NPV为71．7％和74．5％，也高于ECG、cTnI、CK-MB，四者结合为95．5％和94．2％；但IMA对于发病〉6h的ICP则无诊断作用。结论 IMA是诊断ICP的早期敏感生化指标，对于发病〈6h（尤其是〈3h）的ICP诊断具有较高的敏感性和NPV，优于ECG、CK-MB、cTnI；将IMA与其他指标结合，可进一步提高对ICP的诊断价值。     

急性心肌梗死急诊介入治疗的临床评价

目的探讨急诊经皮冠状动脉介入治疗术(PCI)对ST段抬高型急性心肌梗死(STAMI)的治疗价值。方法STAMI46例,在发病12h内行急诊冠状动脉造影及直接冠脉支架置入术(DS)或预扩张后支架置入术(PS),观察术中心律失常发生情况,术后TIMI分级、心电图,出院前左室射血分数(LVEF)和住院期间主要不良心脏事件(MACE)等。结果DS组与PS组各项指标无差异,44例达TIMI3级,成功率达95.7%,ST段回落率67.4%,平均LVEF(49.4±9.46)%,术中心律失常发生率21.7%,无MACE发生。结论对于发病12h的STAMI患者,行急诊PCI,可开通梗塞相关动脉(IRA),改善心肌再灌注和近期预后。