Use of X-ray Tomography to Map Crystalline and Amorphous Phases in Frozen Biomaterials

The outcome of both cryopreservation and cryosurgical freezing applications is influenced by the concentration and type of the cryoprotective agent (CPA) or the cryodestructive agent (i.e., the chemical adjuvants referred to here as CDA) added prior to freezing. It also depends on the amount and type of crystalline, amorphous and/or eutectic phases formed during freezing which can differentially affect viability. This work describes the use of X-ray computer tomography (CT) for non-invasive, indirect determination of the phase, solute concentration and temperature within biomaterials (CPA, CDA loaded solutions and tissues) by X-ray attenuation before and after freezing. Specifically, this work focuses on establishing the feasibility of CT (100–420 kV acceleration voltage) to accurately measure the concentration of glycerol or salt as model CPA and CDAs in unfrozen solutions and tissues at 20°C, or the phase in frozen solutions and tissue systems at −78.5 and −196°C. The solutions are composed of water with physiological concentrations of NaCl (0.88% wt/wt) and DMEM (Dulbecco’s Modified Eagle’s Medium) with added glycerol (0–8 M). The tissue system is chosen as 3 mm thick porcine liver slices as well as 2 cm diameter cores which were either imaged fresh (3–4 h cold ischemia) or after loading with DMEM based glycerol solutions (0–8 M) for times ranging from hours to 7 days at 4°C. The X-ray attenuation is reported in Hounsfield units (HU), a clinical measurement which normalizes X-ray attenuation values by the difference between those of water and air. NaCl solutions from 0 to 23.3% wt/wt (i.e. water to eutectic concentration) were found to linearly correspond to HU in a range from 0 to 155. At −196°C the variation was from −80 to 95 HU while at −78.5°C all readings were roughly 10 HU lower. At 20°C NaCl and DMEM solutions with 0–8 M glycerol loading show a linear variation from 0 to 145 HU. After freezing to −78.5°C the variation of the NaCl and DMEM solutions is more than twice as large between −90 and +190 HU and was distinctly non-linear above 6 M. After freezing to −196°C the variation of the NaCl and DMEM solutions increased even further to −80 to +225 HU and was distinctly non-linear above 4 M, which after modeling the phase change and crystallization process is shown to correlate with an amorphous phase. In all tissue systems the HU readings were similar to solutions but higher by roughly 30 HU, as well as showing some deviations at 0 M after storage, probably due to tissue swelling. The standard deviations in all measurements were roughly 5 HU or below in all samples. In addition, two practical examples for CT use were demonstrated including: (1) glycerol loading and freezing of tissue cores and, (2) a mock cryosurgical procedure. In the loading experiment CT was able to measure the permeation of the glycerol into the sample at 20°C, as well as the evolution of distinct amorphous vs. crystalline phases after freezing to −196°C. In the mock cryosurgery example, the iceball edge was clearly visualized, and attempts to determine the temperature within the iceball are discussed. An added benefit of this work is that the density of these frozen samples, an essential property in measurement and modeling of thermal processes, was obtained in comparison to ice.     

Google Glass for Documentation of Medical Findings: Evaluation in Forensic Medicine

Background

Google Glass is a promising premarket device that includes an optical head-mounted display. Several proof of concept reports exist, but there is little scientific evidence regarding its use in a medical setting.

Objective

The objective of this study was to empirically determine the feasibility of deploying Glass in a forensics setting.

Methods

Glass was used in combination with a self-developed app that allowed for hands-free operation during autopsy and postmortem examinations of 4 decedents performed by 2 physicians. A digital single-lens reflex (DSLR) camera was used for image comparison. In addition, 6 forensic examiners (3 male, 3 female; age range 23-48 years, age mean 32.8 years, SD 9.6; mean work experience 6.2 years, SD 8.5) were asked to evaluate 159 images for image quality on a 5-point Likert scale, specifically color discrimination, brightness, sharpness, and their satisfaction with the acquired region of interest. Statistical evaluations were performed to determine how Glass compares with conventionally acquired digital images.

Results

All images received good (median 4) and very good ratings (median 5) for all 4 categories. Autopsy images taken by Glass (n=32) received significantly lower ratings than those acquired by DSLR camera (n=17) (region of interest: z=–5.154, P<.001; sharpness: z=–7.898, P<.001; color: z=–4.407, P<.001, brightness: z=–3.187, P=.001). For 110 images of postmortem examinations (Glass: n=54, DSLR camera: n=56), ratings for region of interest (z=–8.390, P<.001) and brightness (z=–540, P=.007) were significantly lower. For interrater reliability, intraclass correlation (ICC) values were good for autopsy (ICC=.723, 95% CI .667-.771, P<.001) and postmortem examination (ICC=.758, 95% CI .727-.787, P<.001). Postmortem examinations performed using Glass took 42.6 seconds longer than those done with the DSLR camera (z=–2.100, P=.04 using Wilcoxon signed rank test). The battery charge of Glass quickly decreased; an average 5.5% (SD 1.85) of its battery capacity was spent per postmortem examination (0.81% per minute or 0.79% per picture).

Conclusions

Glass was efficient for acquiring images for documentation in forensic medicine, but the image quality was inferior compared to a DSLR camera. Images taken with Glass received significantly lower ratings for all 4 categories in an autopsy setting and for region of interest and brightness in postmortem examination. The effort necessary for achieving the objectives was higher when using the device compared to the DSLR camera thus extending the postmortem examination duration. Its relative high power consumption and low battery capacity is also a disadvantage. At the current stage of development, Glass may be an adequate tool for education. For deployment in clinical care, issues such as hygiene, data protection, and privacy need to be addressed and are currently limiting chances for professional use.     

恶性肿瘤的90Y-玻璃微球瘤内注射治疗及其临床效果观察

目的 探讨90Y-玻璃微球介入治疗晚期恶性肿瘤的疗效.方法 共18例恶性肿瘤病人,其中肝癌6例,肺癌5例,颈部淋巴结转移癌5例,上颌窦癌1例,肺癌胸壁转移1例,均经病理诊断证实.采取直接注入或者利用B超和CT引导下将90Y-玻璃微球引入肿瘤组织.结果 18例肿瘤中,完全消失（CR）为2例,部分缩小（PR）为9例,肿瘤稳定（SD）为6例,肿瘤进展（PD）为1例.14例病人可见疼痛减轻,4例疼痛未见明显缓解.结论 本方法可在晚期恶性肿瘤治疗上发挥重要作用,有较大临床应用前景.     

改性玻璃离子水门汀应力松弛蠕变实验

文题释义：黏弹性力学：连续介质力学的重要分支,又称黏弹性理论,研究黏弹性物质的力学行为、本构关系及其破坏规律,以及黏弹性体在外力和其他因素作用下的变形和应力分布。聚合物、混凝土、金属、岩石、土壤、石油、肌肉、血液和骨骼等,在一定条件下既具有弹性性质又具有黏性性质,这种兼具弹性和黏性性质的材料称为黏弹性材料,含黏弹性固体与黏弹性流体,又可分为线性黏弹性体和非线性黏弹性体。线性黏弹性体的两种极端情况即为胡克体(遵循胡克定律)和牛顿流体(遵循牛顿粘性定律)。 生物力学：是应用力学原理和方法对生物体中的力学问题定量研究的生物物理学分支,其研究范围从生物整体到系统、器官(包括血液、体液、脏器、骨骼等),从鸟飞、鱼游、鞭毛和纤毛运动到植物体液的输运等。 物力学的基础是能量守恒、动量定律、质量守恒三定律并加上描写物性的本构方程。生物力学研究的重点是与生理学、医学有关的力学问题,依研究对象的不同可分为生物流体力学、生物固体力学和运动生物力学等。 背景：以往对改性玻璃离子水门汀的力学性能研究多以压缩、弯曲实验居多,关于玻璃离子水门汀加入锶羟基磷灰石后的应力松弛、蠕变实验研究鲜有报道。 目的：对比分析传统玻璃离子水门汀、复合树脂釉质粘接剂、改性玻璃离子水门汀的应力松弛、蠕变特性。 方法：按质量比15%向玻璃离子水门汀中加入掺锶羟基磷灰石,制备改性玻璃离子水门汀。制作改性玻璃离子水门汀、复合树脂釉质粘接剂与传统玻璃离子水门汀试样,3组各取10个试样进行应力松弛实验,另取10个试样进行蠕变实验。 结果与结论：①应力松弛实验7 200 s时,传统玻璃离子水门汀组应力下降了1.18 MPa,复合树脂釉质粘接剂组应力下降了1.39 MPa,掺锶羟基磷灰石复合玻璃离子水门汀组应力下降了1.38 MPa;传统玻璃离子水门汀组应力下降量小于掺锶羟基磷灰石复合玻璃离子水门汀组、复合树脂釉质粘接剂组(P < 0.05),掺锶羟基磷灰石复合玻璃离子水门汀组和复合树脂釉质粘接剂组应力下降量无差异(P > 0.05)。②蠕变实验7 200 s时,传统玻璃离子水门汀组应变上升了0.24%,复合树脂釉质粘接剂组应变上升了0.33%,掺锶羟基磷灰石复合玻璃离子水门汀组应变上升了0.32%;传统玻璃离子水门汀组应变上升量小于掺锶羟基磷灰石复合玻璃离子水门汀组、复合树脂釉质粘接剂组(P < 0.05),掺锶羟基磷灰石复合玻璃离子水门汀组试和复合树脂釉质粘接剂组应变上升量无差异(P > 0.05)。③结果表明,15%掺锶羟基磷灰石提高和改善了玻璃离子水门汀的黏弹特性,有利于其与黏结物体的黏结,有利于提高黏结强度。 ORCID: 0000-0003-1024-5733(丁洁) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Laser microdissection and pressure catapulting (LMPC) in paraffin sections mounted on glass slides. A methodological report

The technique of laser microdissection together with laser pressure catapulting (LMPC) is demonstrated in paraffin sections obtained from surgical specimens of brain tumors mounted on glass slides. A sufficient and precise application of microdissection techniques in tissue on glass slides is worthwhile, since it offers the possibility of a retrospective analysis of archived paraffin sections in histopathology. We could demonstrate a precise dissection of areas in tissues of different thicknesses (4 microm and 20 microm). Areas of tissue mounted directly on glass need to be dissected in a scanning mode in order to remove the total region in form of small tissue fragments row by row. This mode provided a precise microdissection of tissue areas of different sizes and shapes. A successful molecular biological analysis of the microdissected regions could be demonstrated. As an example for such an analysis, differential-PCR for detecting an amplification of the gene for the epidermal growth factor receptor (EGFR) was performed.     

两种材料修复楔状缺损疗效的5年观察

目的 比较玻璃离子水门汀和光固化树脂两种材料对楔状缺损修复的临床疗效.方法 76例489颗楔缺牙分别用玻璃离子水门汀和光固化树脂,于修复后每年用改良的USPHS系统评价修复体的质量,随访至修复后5年.比较两组间修复体的质量和具体失败原因.结果 修复后1年和2年,光固化树脂组修复体优良率均优于玻璃离子体组(X2=4.83,P=0.028;X2=4.07,P=0.044).修复后3～5年,修复体总优良率继续下降,但两组没有差异(X2=1.05,P=0.305;X2=0.902,P=0.342;X2=0.002,P=0.966).修复后2年和5年失败的具体因素,两组间构成比相当(X2=1.623,P=0.898;X2=1.530;P=0.910).结论 修复2年内,光固化树脂治疗楔状缺损优于玻璃离子水门汀,但2年后,两种材料的修复体质量均快速下降.     

三种方法修复牙齿楔状缺损的临床疗效观察

目的探讨较理想的修复牙齿楔状缺损的材料和方法。方法82例286颗中、深度楔状缺损牙随机分成A、B、C3组,分别用光固化复合树脂、FX-II型玻璃离子、FX-II型玻璃离子水门汀加光固化复合树脂夹层设术修复楔状缺损,随访2年后疗效。结果A组成功率为83.3%,B组成功率为93.5%,C组成功率为95.9%。A与B组、A与C组,P〈0.05,B与C组,P〉0.05。结论在中、深度楔状缺损治疗中,玻璃离子,光固化玻璃离子夹层技术均优于光固化复合树脂治疗方法。     

PP—g—MAZn离聚物的固相法合成与表征

以ＤＣＰＯ为引发剂，将ＰＰ粉末通过固相法与马为酸锌发生接枝反应，合成不同接枝率的ＰＰ－ｇ－ＭＡＺｎ离聚物。考察反应温度，引发剂浓度，单体的用量对接枝率的影响，研究表明，（１）ＰＰ－ｇ－ＭＡＺｎ离聚物的ＦＴＩＲ图中，１５４０ｃｍ＾－１－１６４３ｃｍ＾－１之间出现宽的峰，说明ＭＡＺｎ与ＰＰ发生了接枝反应；（２）ＰＰ－ｇ－ＭＡＺｎ的ＷＡＸＤ谱中在２θ＝１０．６°，３１．２°，３３．２°，处有衍射峰，表明     

The use of glass ionomer cements in both conventional and surgical endodontics

The capacity to bond to dental tissues, especially to dentine, their long-term fluoride release and their biocompatibility make glass ionomer cements (GICs) advantageous for use in endodontics, as well as in restorative dentistry. This review provides information on the basic properties of GICs, such as adhesion, antimicrobial effects and biocompatibility, particularly as they relate to use in endodontics. Indications for the use of GICs in endodontics are orthograde root canal sealing, root-end filling, repair of perforations and root resorption defects, treatment of vertical fractures and maintenance of the coronal seal. The paper includes a review on each of these indications. It is concluded that in spite of the critical handling characteristics and the inconclusive findings regarding sealing ability and antimicrobial activity, there is substantial evidence to confirm their satisfactory clinical performance. Both soft tissue and bone compatibility make them suitable for use during endodontic surgery.