Placental Elasticity as a New Non-invasive Predictive Marker of Pre-eclampsia

Point shear wave elastography is an ultrasonography technique used to evaluate tissue elasticity. We examined whether placental elasticity is useful for predicting the onset of pre-eclampsia. Two hundred twenty-one participants were divided into two groups: one group at low risk (n?=?185) and the other at high risk (n?=?36) for pre-eclampsia. The two groups were compared with respect to shear wave velocity (SWV) of the placenta. Use of SWV as a predictor of pre-eclampsia was also investigated by creating a receiver operating characteristic (ROC) curve. The ROC curve was used to set a cutoff SWV value for predicting pre-eclampsia. The SWV of the high-risk group was significantly higher than that of the low-risk group (p < 0.001). Thirteen participants developed pre-eclampsia after SWV measurements, and the SWVs of these participants were significantly higher than those of participants in who pre-eclampsia did not develop. The cutoff value and area under the ROC curve were 1.188 m/s and 0.9118, respectively. Placental elasticity was significantly increased even before the onset of pre-eclampsia onset and, thus, may be a parameter used to predict the onset of pre-eclampsia.     

REVIEW: The Zero-Stress State of the Gastrointestinal Tract:

The stresses and strains that remain in an organ when the external load is removed (the no-load state) are called residual stresses and strains. They can be relieved by cutting up the organ to obtain the zero-stress configuration. This phenomenon was demonstrated more than 15 years ago in cardiovascular research but until recently it was not realized by the gastrointestinal research community. The function of the gastrointestinal tract is to propel food by peristaltic motion, which is a result of the interaction of the tissue forces in the wall and the hydrodynamic forces in the food bolus. To understand the tissue forces, it is necessary to know the stress–strain relationships of the tissues that must be measured in reference to the zero-stress state. It has become clear that the zero-stress configuration of the gastrointestinal tract is very different from that of the no-load condition and that the zero-stress state is sensitive to structural and mechanical remodeling. The purpose of this review is to describe the basic theory and experiments of residual stress and to explore its physiological and pathophysiological implications in the gastrointestinal system.     

健康人与高血压患者动脉弹性功能比较

目的　比较不同年龄、血压水平的健康人和高血压患者动脉弹性功能。方法　选取健康志愿者和高血压患者共551人 ,其中男性 30 3人 ,女性 2 4 8人 ,平均年龄为 56 9± 1 3 4岁。分别根据年龄和血压水平分组 ,使用DO 2 0 2 0动脉功能测定仪检测桡动脉脉搏波形和动脉弹性指数C1 和C2 ,进行比较研究。结果　随着年龄不断增高 ,健康人和高血压病人的C1 和C2 值逐渐下降。健康组和高血压组男性的C1 和C2 均高于女性 ,P <0 0 1。校正年龄因素影响后 ,随着血压水平的升高 ,大小动脉弹性指数下降。高血压病人大动脉弹性明显比正常血压者低。处于正常高限者小动脉弹性指数C2 显著低于理想和正常血压者 ,与 1级高血压组无明显差别。简单相关分析表明年龄、收缩压、舒张压、脉压和心率与动脉弹性指数C1 和C2 存在明显负相关 ,其中脉压与C1 相关性 (r =- 0 60 2 ,P <0 0 1 )最为显著 ,而C2 与年龄相关性 (r=- 0 457,P <0 0 1 )最为明显。结论　 (1 )年龄增大、血压升高与血管弹性下降密切相关 ,血管弹性检测可能比测量血压更为有效反映血管功能状态。 (2 )小动脉弹性指数 (C2 )为一敏感反映动脉损害的指标 ,有助于筛选出处于亚临床状态的心血管病人。     

THE DEMAND FOR PREVENTIVE AND RESTORATIVE DENTAL SERVICES

Chronic tooth decay is the most common chronic condition in the United States among children ages 5–17 and also affects a large percentage of adults. Oral health conditions are preventable, but less than half of the US population uses dental services annually. We seek to examine the extent to which limited dental coverage and high out‐of‐pocket costs reduce dental service use by the nonelderly privately insured and uninsured. Using data from the 2001–2006 Medical Expenditure Panel Survey and an American Dental Association survey of dental procedure prices, we jointly estimate the probability of using preventive and both basic and major restorative services through a correlated random effects specification that controls for endogeneity. We found that dental coverage increased the probability of preventive care use by 19% and the use of restorative services 11% to 16%. Both conditional and unconditional on dental coverage, the use of dental services was not sensitive to out‐of‐pocket costs. We conclude that dental coverage is an important determinant of preventive dental service use, but other nonprice factors related to consumer preferences, especially education, are equal if not stronger determinants. Copyright © 2013 John Wiley & Sons, Ltd.     

乳腺肿块良恶性诊断中使用超声弹性成像的临床研究

目的探讨乳腺肿块良恶性诊断中使用超声弹性成像的临床研究。方法选取我院接受乳腺肿块切除的住院病人,收集时间为2008年2月—2014年8月,共计350例,平均年龄（36.2±23.3）岁,中位年龄44.5岁,乳腺病灶共350个,患者在接受乳腺肿块切除前均行二维B超及超声弹性检查,350个病个均经手术后病理切片证实,其中良性病个170个,恶性病个180个,分别定义为良性组,恶性组。对所有乳腺病灶进行弹性成像打分,并且与最终的病理诊断进行对比。结果良性组170个结节,其中63个乳腺病,57个纤维腺瘤,17个乳腺炎,13个导管内乳头状瘤,6个纤维脂肪瘤,5个硬化性腺病、5个血管脂肪瘤,4个黏液腺瘤。恶性组中：160个浸润性导管癌,6个浸润性小叶癌,5个叶状囊肉瘤,3个湿疹样癌,黏液腺癌2个,1个乳头样癌,1个原位癌,1个髓样癌,1个高度糖原透明癌。170例良性结节平均得分为（1.76±0.65）分,180例;恶性结节平均得分为（4.3±1.21）分,良性结节平均得分与恶性结节平均得分差异有统计学意义（P〈0.05）。恶性组诊断准确率为96.7%,良性组诊断准确率为96.2%,恶性组诊断准确率与良性组诊断准确率作为差异无统计学意义（P〉0.05）。结论超声弹性成像能准确的区分良恶性乳腺肿块,对临床诊断乳腺肿块性质提供了新的无创手段。     

甲状腺良、恶性结节中声脉冲辐射力弹性成像的诊断效果

目的针对甲状腺良、恶性结节中声脉辐射力弹性成像的诊断效果进行研究分析。方法随机选择2013年4月—2014年4月期间,在该院进行甲状腺结节诊断治疗的患者120例作为研究对象,所有患者采用成声脉冲辐射力弹性成像以及常规超声技术进行诊断检查,对甲状腺结节的良、恶性成像诊断的结果进行比较分析。结果使用声脉冲辐射力弹性成像对甲状腺良、恶性进行诊断,良性结节的SWV平均值与恶性结节的SWV平均值≤2.0 m/s,2.1-3.0 m/s,〉3.0 m/s所占的比例分别为51.67%、0.00%,50.00%、31.67%,15.00%、0.70%,均有显著差异,P值均〈0.05,具有统计学意义。甲状腺结节良性、恶性的SWV值分布分别为（2.24±0.79）、（5.06±2.87）,有显著差异,P〈0.05,具有统计学意义。甲状腺良性、恶性结节SWV与周围甲状腺组织的SWV比值的分布,≤1.0、1.0-2.0、〉2.0所占比例分别为28.33%、6.67%,63.33%、45.00%,8.33%、48.33%,均有显著差异,P值均〈0.05,具有统计学意义。结论在甲状腺良性、恶性结节的诊断中,应用声脉冲辐射力弹性成像技术进行诊断,可以将甲状腺结节的弹性特征呈现出来,在甲状腺结节的良性和恶性诊断、鉴别中,具有重要的意义。     

乳腺肿块良恶性诊断中使用超声弹性成像的临床研究

目的探讨乳腺肿块良恶性诊断中使用超声弹性成像的临床研究。方法选取我院接受乳腺肿块切除的住院病人,收集时间为2008年2月至2014年8月,共计350例,平均年龄（36.2±23.3）岁,中位年龄44.5岁,乳腺病灶共350个,患者在接受乳腺肿块切除前均行二维B超及超声弹性检查,350个病个均经手术后病理切片证实,其中良性病个170个,恶性病个180个,分别定义为良性组,恶性组。对所有乳腺病灶进行弹性成像打分,并且与最终的病理诊断进行对比。结果良性组170个结节,其中63个乳腺病,57个纤维腺瘤,17个乳腺炎,13个导管内乳头状瘤,6个纤维脂肪瘤,5个硬化性腺病、5个血管脂肪瘤,4个黏液腺瘤。恶性组中：160个浸润性导管癌,6个浸润性小叶癌,5个叶状囊肉瘤,3个湿疹样癌,黏液腺癌2个,1个乳头样癌,1个原位癌,1个髓样癌,1个高度糖原透明癌。170例良性结节平均得分为1.76±0.65,180例;恶性结节平均得分为4.3±1.21,良性结节平均得分与恶性结节平均得分差异有统计学意义（P〈0.05）。恶性组诊断准确率为96.7%,良性组诊断准确率为96.2%,恶性组诊断准确率与良性组诊断准确率作为差异无统计学意义（P〉0.05）。结论超声弹性成像能准确的区分良恶性乳腺肿块,对临床诊断乳腺肿块性质提供了新的无创手段。     

ALT持续正常及持续或间断升高的慢性乙型肝炎患者肝脏硬度值分析

目的目前ALT持续正常(PNALT)以及持续或间断升高(PIEALT)的慢性乙型肝炎(CHB)患者肝脏硬度值(LSM)的数据十分有限。本研究对该组患者LSM范围及其影响因素进行了探讨,以供临床应用参考。方法将在2012年9月-2013年3月于本院就诊的208例初治CHB患者纳入研究,均接受瞬时弹性扫描仪(FS)检查。PNALT组:在最近1 a随访至少3次,每次间隔2个月以上,ALT水平均正常,入组时ALT正常;PIEALT组进一步分为ALT轻度升高(过去1 a随访中ALT水平至少有1次升高但2×ULN)以及ALT明显升高(过去1 a随访中ALT水平至少有1次升高2×ULN),入组时ALT2×ULN。根据现有的研究结果,当ALT2×ULN时,用于诊断以及排除进展性肝纤维化的标准分别为LSM≥10.6 kPa和LSM7.4 kPa。计量资料分析采用t检验、方差分析和秩和检验,计数资料采用χ2检验,相关因素采用双变量相关分析及Logistic回归分析。结果受试人群平均LSM为(6.2±2.9)kPa。在PNALT患者中,LSM≥7.4 kPa占14.3%(18/126),LSM≥10.6 kPa占2.4%(3/126)。在总体PIEALT患者中,这个比例分别是35.4%(29/82)以及13.4%(11/82)。多元回归分析中,ALT1×ULN(OR=2.63,P=0.037)、男性(OR=5.29,P=0.012)是LSM≥7.4 kPa的独立影响因素;HBV DNA定量5 log10拷贝/ml是LSM≥10.6 kPa唯一的独立影响因素(OR=13.84,P=0.046)。结论在PIEALT和PNALT的CHB患者中,分别有35%及14%的患者不能排除进展性肝纤维化的可能;大约13%的PIEALT患者根据LSM结果可判断为进展性肝纤维化。对于ALT1×ULN、HBV DNA拷贝数的对数值大于5的男性CHB患者,建议对其进行密切随访。     

超声应变力成像对诊断甲状腺良性结节纤维化的应用价值

目的 探讨超声应变力成像对诊断甲状腺良性结节纤维化的应用价值。方法 选取本中心经病理证实为良性的甲状腺结节 155个,术前均行超声弹性成像检查,依据病理结果将其分为伴纤维化组（n=125）、无纤维化组（n=30）,并对 2组间应变率比值进行对比分析。以病理结果为金标准,计算应变率比值在诊断甲状腺良性结节是否伴有纤维化的敏感度和特异度。结果 伴纤维化组应变率比值［3.14（1.143,7.050）］高于良性无纤维化组［1.41（1.020,2.345）］（P＜0.05）。经 ROC曲线分析,应变率比值＞2.62,提示甲状腺良性结节可能存在纤维化,此时应变率比值的曲线下面积为 0.664（0.548,0.780）,敏感度为 56.7%,特异度为 77.6%。结论 超声弹性成像应变率比值对诊断甲状腺良性结节纤维化有一定的应用价值。     

Acoustic excitations and elastic heterogeneities in disordered solids

In the recent years, much attention has been devoted to the inhomogeneous nature of the mechanical response at the nanoscale in disordered solids. Clearly, the elastic heterogeneities that have been characterized in this context are expected to strongly affect the nature of the sound waves which, in contrast to the case of perfect crystals, cannot be completely rationalized in terms of phonons. Building on previous work on a toy model showing an amorphization transition, we investigate the relationship between sound waves and elastic heterogeneities in a unified framework by continuously interpolating from the perfect crystal, through increasingly defective phases, to fully developed glasses. We provide strong evidence of a direct correlation between sound wave features and the extent of the heterogeneous mechanical response at the nanoscale.In crystals, molecules thermally oscillate around the periodic lattice sites and vibrational excitations are well understood in terms of quantized plane waves, the phonons (1). The vibrational density of states (vDOS) in the low-frequency regime is well described by the Debye model, where the vibrational modes are the acoustic phonons. In contrast, disordered solids, including structural glasses and disordered crystals, exhibit specific vibrational properties compared with the corresponding pure crystalline phases. It is not possible here to give a fair review of the extensive theoretical and experimental work generated by these issues; we therefore mention below a few facts that we consider the most relevant in the present context. The origin of the vDOS modes in excess over the Debye prediction around ω ∼1 THz, the so-called Boson peak (BP), is still debated (see, among many others, refs. 2 and 3). At the BP frequency, Ω^BP, localized modes have also been observed (4). Acoustic plane waves, which are exact normal modes in crystals, can still propagate in disordered solids. Indeed, at low frequencies, Ω, and long wavelengths, Λ, acoustic sound waves do not interact with disorder and can propagate conforming to the expected macroscopic limit. However, as Ω is increased beyond the Ioffe–Regel (IR) limit, Ω^IR, acoustic excitations interact with the disorder and are significantly scattered (5–7). Interestingly, this strong scattering regime occurs around the BP position, Ω^IR ∼ Ω^BP (8, 9). The exact origin of this phenomenon and its connection to the BP remain elusive.A possible rationalization of the above issues is based on the existence of elastic heterogeneities (10), which can originate from structural disorder, as in structural glasses (2), or disordered interparticle potentials, even in lattice structures such as disordered colloidal crystals (11). In the heterogeneous-elasticity theory of refs. 7 and 12 this amounts to consider spatial statistical fluctuations of the shear modulus. Within the framework of jamming approaches and using effective medium theories, elastic heterogeneities are related to the proximity of local elastic instabilities (13). Recent simulation work (14–16) has clearly demonstrated their existence in disordered solids. This is at variance with the case of simple crystals, which are characterized by a fully affine response and homogeneous moduli distributions (17). More specifically, in the large length scale limit, macroscopic moduli are observed. In contrast, as the length scale is reduced, moduli heterogeneities are detected, at a typical length scale ξ ≃ 10−15σ (15), where σ is the typical atomic diameter. Breakdown of both continuum mechanics (18) and Debye approximation (5, 6) has been demonstrated at the same mesoscopic length-scale ξ, where they are still valid for crystals. Remarkably, the wave frequency corresponding to the wavelength Λ ∼ ξ is very close to Ω^IR ∼ Ω^BP (19). Altogether these results indicate that a close connection must exist between elastic heterogeneities and acoustic excitations. In this paper we precisely address this point.In ref. 20 we considered a numerical model featuring an amorphization transition (21). We showed how to systematically deform the local moduli distributions, evaluated by coarse-graining the system in small domains of linear length scale w. We characterized the degree of elastic heterogeneity in terms of SD of those distributions and studied the effect on normal modes (eigenvalues of the Hessian matrix) and thermal conductivity. Building on that work, we are now in the position to investigate the relation between elastic heterogeneities and acoustic excitations, unifying in a single framework ordered and disordered solid states and considering quantities directly probed by experiments. By interpolating in a controlled way from perfect crystals, through increasingly defective phases, to fully developed amorphous structures, we (i) calculate the dynamical structure factors, extracting the relevant spectroscopic parameters; (ii) characterize the wave vector dependence of sound velocity and broadening of the acoustic excitations and clarify their nature in terms of the IR limit; and (iii) provide, for the first time to our knowledge, direct evidence of the correlation of the excitations lifetimes and Ω^IR with the magnitude of the elastic heterogeneities.