下颌角缺损修复钛板构型的拓扑优化研究

目的 为下颌骨缺损修复植入体的构型设计提供优化方法和基本构型。方法 使用基于密度法的拓扑优化算法,针对下颌角缺损的修复体钛板进行拓扑优化计算。结果 通过比较和分析体积分数F和惩罚因子p对优化构型的影响,最终选择F=0.65和p=3.5作为优化的参数组合。用此参数组合对下颌角缺损修复体进行优化计算,认为3孔构型是其基本优化构型。同时发现,对同一构型,磨牙咬合较前牙咬合对植入体应力分布影响更显著。结论 获得了一套适用于下颌骨修复植入体构型优化的参数和方法,得到了优化后的钛板基本构型,可为临床下颌缺损修复体的设计提供借鉴。     

三维打印颌骨支架的研究进展

口腔颌面部肿瘤、外伤等常造成大范围的颌骨缺损,导致患者面部畸形、语言和咀嚼功能障碍等,严重影响患者生活质量。三维打印(3DP),又名"增材制造",是一类将材料逐层添加来制造三维物体的技术。利用三维打印并结合影像数据、计算机设计和个性化制造颌骨修复支架,可以对复杂形态的颌骨缺损进行精确的修复重建,相对于传统的颌骨修复方式具有独特的优势,成为近年来颌骨组织工程支架研究的热点。本文就三维打印颌骨支架在颌骨修复中的应用作一综述,为临床上颌骨缺损的修复提供新思路。     

聚醚醚酮(PEEK)个性化重建板修复下颌骨缺损的三维有限元分析

目的应用三维有限元分析聚醚醚酮(PEEK)及其复合物重建板修复下颌骨缺损的应力分布。方法通过CBCT、Mimics、SolidWorks、Geomagic Studio和ANSYS Workbench等软件建立钛合金、聚醚醚酮(PEEK)、30%碳纤维增强聚醚醚酮(carbon-fiber-reinforced polyetheretherketone,CFR-PEEK)、68%CFR-PEEK重建板有限元模型,以钛合金作为对照。分别模拟两种咬合状态。载荷Ⅰ:前牙区垂直加载300 N;载荷Ⅱ:左侧后牙区垂直加载300 N。结果两种载荷下,重建板最大应力与其屈服强度的比值:PEEK模型30%CFR-PEEK模型钛合金模型68%CFR-PEEK模型;颌骨最大应力:PEEK模型30%CFR-PEEK模型钛合金模型68%CFR-PEEK模型。其中,在前牙区垂直载荷下,PEEK模型重建板和颌骨的最大应力都超过了其屈服强度,其他模型的最大应力均低于其屈服强度。结论 68%CFR-PEEK与钛合金有着相似的应力分布,可以满足颌骨缺损重建机械强度的要求,重建板出现断裂的风险较钛合金降低,但应力屏蔽的发生率略增高。研究结果可为修复下颌骨缺损的重建板材料的选择和临床应用提供依据。     

3D生物打印技术及其在牙周骨缺损修复中的应用

与传统的"减材"制造相比,3D打印技术具有精确的个性化设计、快速成型、复杂精细产品制造等"増材"制造的明显优势。近年来,为了提高治疗的个性化及精确性,医学领域已经广泛应用3D生物打印技术进行术前诊断、手术设计、术前模拟以及组织再生等各个阶段。本综述首先介绍3D生物打印技术的概况及其过程,主要分为成像及模型设计、生物材料及细胞类型的选择、不同类型的生物打印等。在口腔牙周缺损修复中,3D生物打印技术通过重建其组织缺损部位的解剖结构,应用生物复合材料逐层精确地堆积出个性化植入物,增加了植入物的稳定性与术后骨结合率,使口腔组织形态及功能都得以恢复。然而,材料选择的局限性等问题给3D生物打印技术在修复牙周骨缺损的发展带来了障碍。本文就3D生物打印技术应用于牙周骨缺损修复中的复合生物材料、细胞、生物活性药物传递等几个方面逐一介绍。     

3D打印钛合金个性化骨盆假体静态和步态有限元分析

目的通过有限元分析方法评价3D打印个性化钛合金骨盆假体在站立位静态和步态下的生物力学性能。方法选取3例不同类型的骨盆肿瘤患者,拟行半骨盆切除人工半骨盆置换术。术前行CT和MRI检查,设计相应的个性化钛合金人工半骨盆假体,利用三维重建技术进行骨盆重建,并与个性化骨盆假体装配。通过AnyBody软件建立患者的人体骨肌系统模型并进行步态动力学分析。导入ABAQUS软件,得到3例重建骨盆模型在静态和步态条件下的应力分布和应力集中区域。结果在静态和步态条件下,3例3D打印钛合金骨盆假体的最大应力均小于钛合金的屈服强度,重建骨盆的骨盆环能够满足应力传导规律,患者术后恢复正常。结论 3D打印个性化钛合金骨盆假体对恢复骨盆环的应力传导效果良好,其有效性和稳定性能够满足人体生物力学要求,分析结果可为临床医生和假体设计人员提供参考。     

基于有限元的单侧上颌骨缺损修复材料的生物力学研究

目的 采用三维有限元分析方法研究不同修复体材料对上颌骨单侧缺损修复的生物力学影响。方法 利用医学图像处理软件MIMICS重建单侧缺损上颌骨模型,采用镜像技术生成修复体模型,经模型处理最终建立单侧缺损修复的上颌骨有限元模型及健康上颌骨有限元模型,并模拟口腔咬合状态下上颌骨受力状态。结果 不同修复材料修复上颌骨的最大应力都集中在与颧骨连接的上颌骨边缘,即颧小肌与提口角肌附着位置。利用三磷酸钙（TCP）复合材料修复后,修复侧的上颌骨边缘应力最小为8.471 MPa;利用羟基磷灰石（HA）修复后,修复侧的上颌骨边缘应力最大,达到17.55 MPa。结论 不同修复材料对修复后上颌骨健侧受力影响不显著,对修复侧受力影响较大。弹性模量的大小可作为临床上用于缺损上颌骨修复的材料选择依据。     

个性化钛植入体修复大面积颅骨缺损的临床疗效分析

目的探索个性化钛植入体修复大面积颅骨缺损的临床疗效。方法利用三维重建和快速自动成型技术,将医用钛合金预制成个性化钛板植入体,对4例大面积颅骨缺损进行修复。结果4例颅骨缺损修复,最大的钛植入体为15cm×13cm,最小的为10cm×8cm,修复后切口愈合良好,术后随访半年至2年,钛合金固定牢靠无排异反应发生,无自觉异物感,符合颅骨缺损部位的生理曲度,对称性好,头部畸形明显改善。结论颅骨缺损的个性化修复标志着颅骨植入体塑形技术已从手工时代进入了数字化设计,具有操作简单、并发症少以及修复精确、良好的生物力学等优点,具有广泛的应用前景。     

个性化钛植入体修复人面积颅骨缺损的临床疗效分析

目的 探索个性化钛植入体修复大面积颅骨缺损的临床疗效.方法 利用三维重建和快速自动成型技术,将医用钛合金预制成个性化钛板植入体,对4例大面积颅骨缺损进行修复.结果 4例颅骨缺损修复,最大的钛植入体为15 cm×13 cm,最小的为10 cm×8 cm,修复后切口愈合良好,术后随访半年至2年,钛合金固定牢靠无排异反应发生,无自觉异物感,符合颅骨缺损部位的生理曲度,对称性好,头部畸形明显改善.结论 颅骨缺损的个性化修复标志着颅骨植入体塑形技术已从手工时代进入了数字化设计,具有操作简单、并发症少以及修复精确、良好的生物力学等优点,具有广泛的应用前景.     

面向3D打印植介入体的生物力学设计

医用植介入体至少包含两类重要的生物力学问题:一是其自身结构的强度等生物力学问题,二是与宿主之间的相互作用;二者对于其成败都非常重要。增材制造技术(3D打印)为个性化植入假体的应用推广带来希望,个性化植入假体具有巨大的临床和市场需求。然而,个性化植入假体设计与临床应用仍有亟待解决的科学和关键技术问题,现有的临床案例主要考虑基于解剖影像几何特征的个性化适配连同医生个人经验进行个性化假体的结构设计,但往往缺乏植入体与宿主组织相互作用的生物力学与力学生物学定量化预测和可靠性评测。本文针对骨盆、肢体修复和足部关节融合所需的个性化植入假体,研究基于生物力学的个性化植入假体的结构优化(强度、可靠性、疲劳特性数值化分析和仿真)技术;探索基于应力影响骨肌相关细胞、组织生长、改重建规律定量化仿真的个性化植入假体的优化设计方法。面向增材制造的多孔植入体对于植入后组织细胞的生长具有诱导性,由于不同形态孔隙的多孔假体,其力学特性、传质特性不同,从而致使其细胞组织相容性差异较大,本文开展了多孔结构拓扑优化研究。开展假体改重建定量生物力学仿真、大规模微孔结构生物力学仿真、疲劳断裂风险数值分析评价、临床特征参数提取、无量纲微孔结构元素库构建、假体高精度制备及处理等关键技术研究。在适宜制备技术方面,研究集成激光清扫的3D打印SLM专用成型设备系统。针对生物医用领域对Ti基合金粉末材料的特殊要求,优化增材制造专用Ti基合金粉末材料的合金体系及化学成分,并结合合金元素对于增材制造过程中激光微熔池行为、凝固组织特征与性能的作用机理研究,微调增材制造用粉末材料的化学成分,研发国产Ti基打印粉材。同时探索个性化植入假体的检测与监管技术。在上述研究基础上开展了临床应用研究。     

基于3D打印多孔支架和植入体的结构设计研究进展

支架或植入体的弹性模量过高会产生应力遮挡效应,引发骨吸收以及后期支架或植入体松动等问题。多孔支架和植入体可以根据需要调整其孔隙率和弹性模量,从而减小应力遮挡,同时多孔结构有利于骨组织的长入,利于骨整合。分别介绍3D打印多孔支架和植入体3种基本结构(均匀多孔结构、类骨小梁结构和功能梯度结构)的设计方法,以及基于计算机辅助设计、隐式曲面、图像、拓扑优化的设计方法,为解决应力遮挡问题和设计3D打印多孔支架和植入体提供参考建议。     

Renal dysplasia and asplenia in two sibs

A family is reported in which two sibs, one male and the other female, both died within 24 hours of birth with enlarged polycystic kidneys. Postmortem histology in the second child showed gross renal dysplasia. In both children the pancreas was enlarged, nodular and cystic but the liver appeared macroscopically normal. In the second child, histological examination confirmed pancreatic fibrosis with cystic dilation of ducts, but showed portal fibrosis with bile duct proliferation in the liver.
This combination of findings is very reminiscent of those in a girl and her brother reported by Ivemark et al. (1959). The children reported here also showed absence or hypoplasia of the spleen, cardiac anomalies and other features of the Ivemark syndrome (Ivemark 1955), a quite different, usually sporadic, congenital disorder. It is suggested that the children described here have a distinct lethal congenital disorder, probably inherited in an autosomal recessive manner.     

Schizophrenia in a North Swedish geographical isolate, 1900–1977. Epidemiology, genetics and biochemistry

Over 200 schizophrenic patients belonging to three major and interrelated pedigree complexes have been investigated over the past 30 years in a North Swedish geographically isolated population, presently numbering about 6,000. An intensive investigation of a number of biochemical correlates and genetic markers in a few selected families belonging to one of the major pedigrees has indicated new strategies for the current research program.
Schizophrenia, as defined operationally, is significantly associated with decreased activities of two enzymes (1) blood platelet monoamine oxidase, (2) plasma dopamine-β-hydroxylase, and (3) with the genetic marker Gc² (group specific antigen). Both enzymes are subject to genetic variation. A positive score for linkage between schizophrenia and low plasma DBH activity has been calculated, but, so far, available data are insufficient for discrimination between linkage and partial contribution of genetically controlled low plasma DBH to the pathogenesis of the disease. Alternatively, both mechanisms could be involved.
As a model for continued research, schizophrenia is explained as based on a double dominant-recessive genotype (Aabb), representing a vulnerability which in about 50 % of cases develops into clinical schizophrenia. It is suggested that the dominant mutation (A) operates on or affects MAO activity, and that the recessive genotype (bb) is instrumental in low variates of DBH activity and very likely such variates within the normal range of physiological variation. Moreover, it is suggested that the combined effects of MAO- and DBH-reduced efficiency on the metabolism of e.g. dopamine could be an essential pathogenic mechanism for the schizophrenic illness which is segregating in this population.     

The dominant diseases of modernized societies as omega-3 essential fatty acid deficiency syndrome: Substrate beriberi

About 1900, modern food selection and processing caused widespread $\text{epidemics}$ of the B vitamin deficiency diseases of beriberi and pellagra which, for genetic reasons, often expressed as different diseases ranging from bowel and heart disease to dermatoses and psychoses. But the B vitamins merely help convert essential fatty acids (EFA) into the prostaglandin (PG) tissue regulators and it now turns out that, through hydrogenation, milling and selection of w3-poor southern foods, we have also been systematically depleting, by as much as 90%, a newly discovered trace Nordic EFA (w3) of special importance to primates and sole precursor of the PG3(4) series, even as a concurrent fiber deficiency increases body demand for EFA. Since substrate EFA is processed by many B vitamin catalysts, an EFA deficiency will mimic a $\text{panh}$ypovitaminosis B, i.e., a mixture of $\text{substrate}$ beriberi and $\text{substrate}$ pellagra resembling vitamin beriberi and pellagra but exhibiting as even more diverse $\text{endemic}$ disease. This would consitute a second stage of the Modern Malnutrition and explain why some workers now hold the dominant diseases of modermized societies to be new, nutritionally based, pellagraform yet lipid-related and to range, once again, from heart disease to psychosis. It is an assumption that our dominant diseases are unrelated to each other or are merely revealed by our diagnostic acumen and therapeutic success; and that hydrogenating millions of tons of food oils annually, to destroy the rancidity producing w3-EFA, is safe for $\text{primates}$. Extensive beriberiform disease is reported here in 32 typical cases taken from medical practice which responds strikingly to linseed oil supplements (60% w3-EFA) in confirmation of identical results in Capuchins.     

What will studies of Fulani individuals naturally exposed to malaria teach us about protective immunity to malaria?

There are an estimated over 200 million yearly cases of malaria worldwide. Despite concerted international effort to combat the disease, it still causes approximately half a million deaths every year, the majority of which are young children with Plasmodium falciparum infection in sub-Saharan Africa. Successes are largely attributed to malaria prevention strategies, such as insecticide-treated mosquito nets and indoor spraying, as well as improved access to existing treatments. One important hurdle to new approaches for the treatment and prevention of malaria is our limited understanding of the biology of Plasmodium infection and its complex interaction with the immune system of its human host. Therefore, the elimination of malaria in Africa not only relies on existing tools to reduce malaria burden, but also requires fundamental research to develop innovative approaches. Here, we summarize our discoveries from investigations of ethnic groups of West Africa who have different susceptibility to malaria.     

'Very sore nights and days': the child's experience of illness in early modern England, c.1580-1720

Sick children were ubiquitous in early modern England, and yet they have received very little attention from historians. Taking the elusive perspective of the child, this article explores the physical, emotional, and spiritual experience of illness in England between approximately 1580 and 1720. What was it like being ill and suffering pain? How did the young respond emotionally to the anticipation of death? It is argued that children’s experiences were characterised by profound ambivalence: illness could be terrifying and distressing, but also a source of emotional and spiritual fulfilment and joy. This interpretation challenges the common assumption amongst medical historians that the experiences of early modern patients were utterly miserable. It also sheds light on children’s emotional feelings for their parents, a subject often overlooked in the historiography of childhood. The primary sources used in this article include diaries, autobiographies, letters, the biographies of pious children, printed possession cases, doctors’ casebooks, and theological treatises concerning the afterlife.     

Guidelines for the Validation and Use of Immunoassays for Determination of Introduced Proteins in Biotechnology Enhanced Crops and Derived Food Ingredients

Recent advancements in agricultural biotechnology have created a need for analytical techniques to determine introduced proteins in crops enhanced through modern biotechnology techniques. These proteins are expressed in plant tissues and may be present in food ingredients. Immunoassays are ideally suited for protein detection and may be used as both quantitative and threshold methods. Microplate ELISA and lateral flow devices are two of the most commonly used immunoassay formats for agricultural biotechnology applications. This paper provides general background information and a discussion of criteria for the validation and application of immunochemical methods to the analysis of proteins introduced into plants and food ingredients using biotechnology methods. It is the result of a collaborative effort of members of the Analytical Environmental Immunochemical Consortium. This collaborative effort represents the combined expertise of several organizations to reach consensus on establishing guidelines for the validation and use of immunoassays. Further, the paper offers developers and users a consistent approach to adopting the technology as well as aid in producing accurate and meaningful results.     

HLA in North Colombia Chimila Amerindians

HLA-A,-B,-C,-DRB1 and -DQB1 alleles have been studied in Chimila Amerindians from Sabana de San Angel (North Colombian Coast) by using high resolution molecular typing. A frequent extended haplotype was found:HLA-A*24:02-B*51:10-C*15:02-BRB1*04:07-DQB1*03:02 (28.7%) which has also been described in Amerinndian Mayos Mexican population (Mexico, California Gulf, Pacific Ocean). Other haplotypes had already been found in Amerindians from Mexico (Pacific and Atlantic Coast), Peru (highlands and Amazon Basin), Bolivia and North USA. A geographic pattern according to HLA allele or haplotype frequencies is lacking in Amerindians, as already known. Also, five new extended haplotypes were found in Chimila Amerindians. Their HLA-A*24:02 high frequencies characteristic is shared with aboriginal populations of Taiwan; also, HLA-C*01:02 high frequencies are found in New Zealand Maoris, New Caledonians and Kimberly Aborigines from Australia. Finally, this study may show a model of evolutionary factors acting and rising one HLA allele frequency (-A*24:02), but not in others that belong to the same or different HLA loci.     

Ultracryotomy: development and application (with examples from the yeast cytology) (author's transl)

The preparation steps usually necessary for obtaining ultrathin frozen sections of biological material (chemical prefixation, enclosing, cryoprotective treatment, freezing, sectioning, and post-staining the sections for transmission electron microscopy) are submitted to a critical analysis. The application of cryo-ultramicrotomy, in particularly for cytochemical purposes, is reviewed. Fundamental considerations of chemical prefixation and poststaining are supported by examples from yeast cytology. Furthermore, the efficiency of the cryo-ultramicrotomy (electron optical resolution of ultrastructural details) is demonstrated on yeast cells and protoplasts.     

The universal muscular chamber. A basic unit of the genitourinary, cardiovascular, gastro-intestinal, skeletal, cutaneous, respiratory and other systems, endocameral hypertension; and spasm, the key to their idiopathic diseases and arthropathies

Starting with the integument, we see many organs are contractile sacs or multiples thereof, which tubes or bags constitute the major part of the entire body. Recognition of this basic unit and its characteristics sheds new light, individually and collectively, on many disorders previously considered unrelated. Muscular tears and perforations develop in the walls of these chambers, being no way peculiar to those organs, wherein, hydrochloric acid occurs. So, it is not necessary to explain the absence of excessive acid from patients who exhibit holes in the gastric, uterine, aortic, duodenal, rectal, pulmonary, retina, and other walls. Muscle, not acid is the great common factor relating idiopathic disorders in the gastrointestinal tract to each other and to similar diseases in other systems. When the units are linked together, the lesions tend to appear as arthropathies, i.e. at the joints. Rephrasing common-place observations, frees us from conventional, conceptual cul-de-sacs. An observation is only as good as its interpretation, so all possibilities must be considered, otherwise, we will remain blinded by our misconceptions.