“X”形弹性脊柱内固定与传统椎弓根内固定的应力分析

背景:目前国内外许多学者研发了多种动态弹性脊柱内固定器,经过生物力学研究、动物实验及临床应用发现,尚无一种脊柱弹性内固定器得到临床上的普遍认可。目的:比较自制"X"形弹性内固定器与传统椎弓根螺钉内固定的应力差异。方法:根据成人脊柱影像学资料,分别建立"X"形弹性脊柱内固定器与传统椎弓根螺钉内固定系统三维有限元模型,比较两组模型在垂直压缩、屈、伸、侧屈、扭转时的力学差异。结果与结论:两模型在垂直压缩状态应下的应力均小于屈、伸、侧屈及扭转状态下的应力;在垂直压缩、前屈、后伸、侧弯及旋转时,"X"形弹性脊柱内固定器的应力更多集中在"X"形连接棒上,而传统椎弓根螺钉内固定的应力更多集中在螺钉近棒段,且"X"形弹性脊柱内固定器螺钉所受应力明显小于传统椎弓根螺钉内固定(P0.001)。表明"X"形弹性内固定器较传统椎弓根螺钉内固定系统更能分担螺钉应力,减少螺钉术后应力集中情况。     

基于CosmosWorks有限元分析在腰椎弹性内固定棒中的应用

背景:引起假体松动的原因主要有力学因素和生物因素,所以应力分布和松动的机制是目前研究热点。目的:应用有限元分析腰椎"U"型弹性内固定器的力学特征。方法:运用solidworks2008三维建模软件建立弹性内固定棒的实体模型,并借助其中的CosmosWorks工具进行有限元分析,分别施加压缩、前屈及拉伸等各种生理载荷,观察模型在不同载荷下弹性内固定器的应力分布,内固定棒在变形过程中其本身结构中各节点、单元的受力、位移情况。结果与结论:"U"型弹性内固定器的应力分布在"U"型连接棒的"U"型区上,应力应变曲线表现出较好的弹性作用。     

腰椎弹性内固定与刚性内固定的应力对比研究

目的:通过有限元的方法评价自行研制的腰椎"U"型弹性内固定器的力学特性,并与传统的刚性内固定器进行比较.方法:选择一名成年患者腰椎标本,以L4～5节段为研究对象,采用64排螺旋CT对其进行层厚1.0 mm的连续水平扫描,将所得图像进行轮廓提取和阈值分割后,借助三维重建软件Mimics11.1、Simpleware和有限元软件Abaqus 6.51软件,建立L4～5节段三维非线性有限元模型.同时根据椎弓根螺钉、连接棒的几何尺寸,力学参数,分别建立两种不同内固定器的有限元模型.然后分别施加压缩、前屈、后伸、侧屈及旋转等各种生理载荷,观察各模型不同载荷下螺钉、连接棒的应力分布.结果:两种内固定器的椎弓根螺钉前、中部的应力差异无统计学意义(P>0.05);刚性固定的椎弓根螺钉与棒连接处是应立集中的部位,该部位的应力远大于弹性固定器,而弹性内固定应力集中的部位均匀的分布于整个U型连接棒上,两模型固定节段螺钉及棒的最大有效应力均出现于前屈时.结论:在加载相同的纵向载荷条件下,刚性内固定器应力主要集中在螺钉与棒交界处,容易易发生螺钉断裂,U型弹性内固定器的应力均匀分布在U型连接棒上,可以减少断钉的现象发生.     

新型脊柱外固定器的生物力学有限元分析

目的：运用有限元方法对新型脊柱外固定器的力学性能进行分析，为其临床应用提供生物力学理论依据。方法：通过有限单元法（FEM）的结构分析功能，建立新型脊柱外固定器的计算机模型，并根据外固定器固定在椎体上的重力受压情况模拟加载，仿真分析模型各部分的应力、应变值及分布和压缩刚度。结果：在模拟受压的情况下，外固定器的应力集中在椎弓根钉与纵向固定螺钉、连接器的接触区，其它部分（包括钉椎体结合部位）的应力分布较均匀；外固定器的刚度较弱，单纯外固定架不足以提供椎体支持刚度。结论：外固定器的椎弓根钉与纵向固定螺钉、连接器的结合部容易产生应力疲劳；外固定器应结合其他的能有效地提供支撑刚度的手段才能更好地应用于临床。     

身体姿势对腰椎小关节受力的影响

目的 :分析脊柱处于不同姿势时腰椎小关节受力大小及变化情况。方法 :采用 8具新鲜脊柱腰骶段 (L1～S1)标本 ,在MTS系统上用压敏片测量L4、5小关节面在中立位和前屈、后伸位时受力大小。结果 :中立位时L4、5小关节受力为 (3 1.16± 7.15 )N ,占轴向压缩载荷的 15 % ;前屈时小关节受力减小 ,前屈 10°、2 0°时受力大小为 (18.3 2± 4.46)N、(9.3 8± 1.82 )N ,占压缩载荷的比例减为 9%、5 % ;后伸时小关节受力增大 ,后伸 10°、2 0°时受力大小为 (4 5 .92± 11.0 6)N、(65 .68± 10 .16)N ,占压缩载荷的比例增至2 3 %、3 3 %。结论 :腰椎小关节在中立位能承受脊柱的一部分压缩载荷 ,且随脊柱姿势不同小关节面受力也不同。     

手舟骨腰部骨折3种内固定方式的有限元分析

目的　通过建立手舟骨腰部骨折三维模型来比较3种不同内固定方式的生物力学差异,为临床内固定方式的选择提供依据。 方法　选取健康志愿者的腕关节CT数据,应用软件建立舟骨腰部骨折的3种内固定方式模型：克氏针固定组、Herbert螺钉固定组、钉脚固定器组。分别在中立握拳位和腕背伸桡偏位施加载荷,并分析舟骨变形量、内固定器械的应力。 结果　在3种内固定装置下舟骨的变形量,克氏针最大,钉脚固定器最小。在两种工况下,舟骨变形量和固定装置的最大应力值不等,但趋势相同,均为钉脚固定器的舟骨变形量最小、所受的最大应力最小。钉脚固定器存在偏心效应,当载荷达到临界值时,易使舟骨愈合面出现开裂或不对称偏心现象。 结论　克氏针固定效果最差,钉脚固定器的固定效果最佳,钉脚固定器术后应适当限制手部负重。     

手舟骨腰部骨折3种内固定方式的有限元分析

目的　通过建立手舟骨腰部骨折三维模型来比较3种不同内固定方式的生物力学差异,为临床内固定方式的选择提供依据。 方法　选取健康志愿者的腕关节CT数据,应用软件建立舟骨腰部骨折的3种内固定方式模型：克氏针固定组、Herbert螺钉固定组、钉脚固定器组。分别在中立握拳位和腕背伸桡偏位施加载荷,并分析舟骨变形量、内固定器械的应力。 结果　在3种内固定装置下舟骨的变形量,克氏针最大,钉脚固定器最小。在两种工况下,舟骨变形量和固定装置的最大应力值不等,但趋势相同,均为钉脚固定器的舟骨变形量最小、所受的最大应力最小。钉脚固定器存在偏心效应,当载荷达到临界值时,易使舟骨愈合面出现开裂或不对称偏心现象。 结论　克氏针固定效果最差,钉脚固定器的固定效果最佳,钉脚固定器术后应适当限制手部负重。     

椎间盘髓核摘除对腰椎间小关节承载功能影响的实验研究

目的分析椎间盘髓核摘除后腰椎小关节受力大小及变化情况。方法采用8具新鲜脊柱腰骶段(L1~S1)标本,在MTS系统上用压敏片分别测量L3-L4、L4-L5两个节段小关节面在中立位和前屈、后伸位时受力大小;摘除L4-L5椎间盘髓核,重复测量。结果完整脊柱标本中,L4-L5与L3-L4节段关节面受力大小相似:中立位时受力占轴向压缩载荷的15%;前屈10°、20°时受力占压缩载荷的比例减为9%、5%;后伸10°、20°时受力占压缩载荷的比例增至23%、33%。L4-L5椎间盘髓核摘除后,L4-L5节段小关节面在各个运动状态下受力均显著增大,而L3-L4节段小关节受力也有增加的趋势。结论腰椎小关节有一定的承载功能。腰椎间盘切除术后,同一平面及相邻平面小关节受力增加,可能引发腰痛。     

腰椎峡部裂机翼型记忆合金固定装置的有限元分析

目的　以正常人体CT影像数据为基础,建立腰椎峡部裂弹性固定有限元模型,分析内固定器受力并对其进行改进。 方法 采用分辨率0.625 mm薄层CT扫描数据,导入 Mimics10.0软件建立三维几何面网格模型,通过Geomagic studio12.0、HyperMesh 10.0前处理,最终导入Abaqus10.1软件生成腰椎峡部裂记忆合金固定模型,并在椎体上表面施加500N压力和7.5 Nm力矩,模拟前屈、后伸、侧屈和旋转四种生理载荷,观察并比较不同载荷下固定装置的应力分布。 结果　机翼型记忆合金固定装置应力集中于侧翼,尤其是侧翼和底座的接合部位,后伸和旋转时最大,容易导致疲劳性断裂。 结论　提高镍钛合金材料质量和工艺水准,术后延长腰围保护时间,以避免机翼型记忆合金固定装置断裂的风险。     

颈椎前路内植入固定系统的有限元模拟及生物力学分析

通过建立一种颈椎前路内植入固定器测试结构的有限元模型,从生物力学角度对该模型在人体生理性压力载荷下的应力-应变分布和运动特性进行分析评估.结果 表明:在生理性轴向压力载荷下,应力-应变集中分布在骨螺钉和内植入固定板的结合部位,钢板上的应力-应变以四个螺钉为定点呈梅花状分布,边缘处应力-应变分布较小,所得结论与临床结果一致.因此,通过该有限元方法可以有效分析颈椎前路内植入固定器在生理性载荷下的应力应变分布,对颈椎前路内植入固定器的外形设计和在临床上的选择提供科学的参考依据.     

The universal muscular chain reaction,muscle spasm,Torsions, ruptures and extravasations. Chameleons of pathology and some manifestations of simple muscular disorders

Most bodily functions require the coordinated actions of complementary and supplementary paired muscle groups. Where this essential muscular cooperation is lacking, hollow organs may burst and others become literally screwed up, giving rise to many similar spastic diseases such as Torticollis, Twisted ovarian cyst, Torsion of the Testis, Volvulus of the intestines, Varicose Veins, Megacolon, Aortamegaly, Scoliosis, Erb's Palsy, Peyronie's Disease, Main-en-Griffe, Undescended Foot (Pes Cavus), Talipes, Strabismus. Spasm is “panenepidemic” and unclassified examples of Torsion Dystonia and Dyskinesia really are as common as debt and taxes.     

Studien zur humoralen Regulation des erythropoetischen Proliferationsspeichers beim Menschen

Zusammenfassung Die Beeinflussung der Erythroblasten-Proliferation durch das Mikromilieu wurde in vitro mittels Auswertung durch Differential- und Mitosezählungen und Signifikanzberechnung vieler Versuchsreihen auch unter verschiedenen pathologischen Bedingungen getestet.Sowohl die Mitosehäufigkeit wie die Ausreifung waren positiv mit dem Erythropoetingehalt des Medium korreliert. Der Effekt wurde durch Folsäure, Ätiocholanolon und cAMP verstärkt. Cobalt stimulierte ebenso wie Testosteron und Methenolon in vitro unabhängig von der Erythropoetinkonzentration im Medium die Erythroblastenproliferation. Ein vermindertes Eisenangebot störte die endgültige Ausreifung der Erythroblasten zu Retikulozyten und bewirkte dadurch eine Ineffektivität der Erythorpoese. Anhaltspunkte für ein Erythrozyten-Chalon oder einen Erythropoetinhemmkörper ließen sich aus unserem Versuchsansatz nicht gewinnen, weil er die Transformation der pluripotenten in die erythropoetin-sensible Stammzelle nicht einschließt. Als Nebenbefund ergab sich eine Stimulation des granulozytopoetischen Proliferationsspeichers durch Serumzusatz zum Medium von Patienten nach akutem Blutverlust und bei Polycythämia vera.Unterstützt durch die Deutsche Forschungsgemeinschaft     

HLA study in Amerindian Bolivia La Paz Aymaras

Aymara people has been a relatively homogeneous group since Spanish Conquest by 1,532 CE, even if previously represented a group of various cultural defined populations who gave rise to them. They were and are established in Andean Altiplano around Titikaka Lake (Bolivia, Peru), Argentina and Chile neighborhood, speak Aymara language and have been maintained after Europeans arrival at a lower social status than Quechua (Inca) speaking people. However, both Aymara and Quechua populations acknowledge Titikaka Lake as center of their origins; both languages are also related. Specific high frequencies of HLA-A*02, -A*24 and -A*68, HLA-B*35, -B*39 and -B*48, HLA-DRB1*08:02, -DRB1*09:01, and -DRB1*14:02, and HLA-DQB1*04:02, -DQB1*03:02 and -DQB1*03:01 alleles are found in Aymaras and HLA class II haplotypes common to Andean Amerindians (DRB1*08:02-DQB1*04:02 and DRB1*04:03-DQB1*03:02), like Quechua, Aymara, Uros, Lamas and Mapuche are also found in Easter and other Pacific Islands. Giant human head stone statues at Tiwanaku (Titikaka Lake, Bolivia) are also found at Easter Island. Thus, it is possible a gene and cultural flow between Andean Amerindians and Easter and other Pacific Islands, as it was demonstrated by Thor Heyerdahl in his Kon-Tiki expedition which reached Pacific Islands sailing from El Callao Harbour (Lima, Peru).     

Hypo- und Hypermagnesämie aus kardiologischer Sicht

Zusammenfassung Eine Reihe pathologischer Zustände bedingen Magnesiummangel. Zustände mit Hypermagnesämie sind ebenfalls bekannt, doch wesentlich seltener. Für den Kardiologen beachtenswert ist, daß unter Therapie mit bestimmten Diuretica bei Herzinsuffizienz, bei Herzinfarkt, Kardiomyopathie, Digitalisintoxikation und bestimmten Herzrhythmusstörungen Hypomagnesämie beobachtet wurde. Leider kann in der klinischen Routine nur ein extracelluläres Magnesiumdefizit durch Serumbestimmungen gemessen werden; über Magnesiummangel einzelner Organe kann nichts ausgesagt werden. Hinweise für Magnesiummangel geben aber neben der Messung des Serumspiegels Anamnese, klinischer Befund, bestimmte EKG-Veränderungen wie auch evtl. Hypokalämie, ein Zustand, bei dem sich oft — besonders bei Aldosteronismus — parallele Veränderungen zeigten.Tierexperimente deuten darauf hin, daß infarktähnliche Läsionen unter Magnesiummangel entstehen, doch ob Herzinfarkt beim Menschen durch Magnesiummangel ausgelöst werden kann, ist noch ungeklärt. In Leichenherzen zeigte sich im Infarktgebiet neben Calciumakkumulation signifikanter Magnesiumverlust, wobei unklar blieb, ob sich Ursache oder Folge des Infarktes widerspiegelten. Falls ein ursächlicher Zusammenhang besteht, ist er im Myokardstoffwechsel selbst zu suchen, wie bei der Alkoholkardiomyopathie, wo myokardialer Magnesiummangel zumindest als pathogenetischer Teilfaktor anerkannt wird. Andererseits versucht man aber auch Beziehungen zwischen Atherosklerose, Blutgerinnung und Hypomagnesämie herzustellen, in der Meinung, daß Magnesiummangel auch über den coronaren Pathomechanismus des Herzinfarktes wirken könnte. Sicher scheint, daß gewisse EKG-Veränderungen und Herzrhythmusstörungen durch einen irritierten Magnesiumhaushalt bedingt sein können, da sie bei Gabe bzw. Entzug von Magnesium verschwinden. Daß Magnesiummangel die Glykosidtoleranz verringert, wird tierexperimentell bestätigt. Unter Hypomagnesämie bewirkt Acetylstrophanthidin eher und länger Rhythmusstörungen als ohne, außerdem lassen diese sich durch Magnesiumgaben eliminieren. Da in gewissen Fällen spontane und digitalisinduzierte Herzrythmusstörungen durch Magnesiuminjektionen beseitigt wurden, scheint Magnesium als Therapeuticum angebracht. Einsatz verschiedener Magnesiumsalze bei Angina pectoris, degenerativen Herzerkrankungen und Herzinsuffizienz ohne geprüften und offensichtlich gestörten Magnesiumhaushalt ist fragwürdig, weil keine eindeutigen klinischen Erfolgsbeweise vorliegen. Immerhin mag es aber larvierte, durch Serumbestimmungen nicht erfaßbare Mangelzustände geben. Allgemein erscheint es aus kardiologischer Sicht ratsam, den Magnesiumhaushalt zu überwachen und in entsprechenden Fällen auszugleichen, um möglichen Myokardläsionen oder fatalen Herzrhythmusstörungen entgegenzuwirken.     

Lipid composition of metacestodes of Taenia taeniaeformis and lipid changes during growth

A lipid analysis was performed on developing metacestodes of Taenia taeniaeformis removed from the livers of rats at times varying from 3 to 35 weeks post infection. Lipid accounted for 7–21% of the dry weight of the parasites. The highest proportions were found at the earlier stages. The distribution was as follows; neutral lipid 27–45%; glycolipid 5–11%; and phospholipid 50–61%. The major neutral lipid was cholesterol, and minor neutral lipids were sterol esters, triglycerides, diglycerides and monoglycerides. Hydrocarbons were present throughout development, but in the highest amounts at the earlier stages. Five different glycolipids were found, all of which were identified as glycosphingolipids. An increase in the proportion of more complex glycolipids was noted as parasites grew older. Ten different phospholipids were identified, with the major components being phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Other phospholipids were: lysophosphatides, phosphatidylinositol, phosphatidic acid, diphosphatidylglycerol, sphingomyelin, and an unknown phospholipid component. Changes in the relative amounts of the two major phospholipids were found when the early and late stages were compared. Two lipids found throughout development were identified as glycosylated dolichol phosphates, and they comprised between 1 and 3% of the total phospholipid fraction. Nineteen fatty acids were detected, and the fatty acid distribution for each lipid class at each stage was determined. Seven major fatty acids were common to each. These were: hexadecanoic, octadecanoic, oleic, linoleic, arachidonic, docosanoic, and docosahexaenoic.     

Environmental risk factors and their role in the management of atopic dermatitis

Introduction: The etiology of atopic dermatitis (AD) is multifactorial with interaction between genetics, immune and environmental factors.

Areas covered: We review the role of prenatal exposures, irritants and pruritogens, pathogens, climate factors, including temperature, humidity, ultraviolet radiation, outdoor and indoor air pollutants, tobacco smoke exposure, water hardness, urban vs. rural living, diet, breastfeeding, probiotics and prebiotics on AD.

Expert commentary: The increased global prevalence of AD cannot be attributed to genetics alone, suggesting that evolving environmental exposures may trigger and/or flare disease in predisposed individuals. There is a complex interplay between different environmental factors, including individual use of personal care products and exposure to climate, pollution, food and other exogenous factors. Understanding these complex risk factors is crucial to developing targeted interventions to prevent the disease in millions. Moreover, patients require counseling on optimal regimens for minimization of exposure to irritants and pruritogens and other harmful exposures.     

Simple Serological Assays for Detecting Rice Tungro Viruses

An attempt was made to produce sensitive and specific polyclonal antisera against the viruses causing rice tungro disease, and to assess their potential for use in simple diagnostic tests. Using a multiple, sequential injection procedure, seven batches of polyclonal antisera against rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV) were produced. These were characterized for their sensitivity and specificity using ring-interface precipitin test and double antibody sandwich (DAS) ELISA. Thirty-one weeks after the first immunization, antiserum batch B6b for RTBV showed the highest ring interface titer (DEP = 1:1920). For RTSV, batches S3, S4b and S5b all had similar titres (DEP = 1:640). In DAS-ELISA, however, significant differences among purified antisera (IgG) batches were observed only at IgG dilution of 10^-3. At that dilution, IgGB4b showed the greatest sensitivity, while IgGS3 showed greatest sensitivity for RTSV. When all IgG batches were tested against 11 tungro field isolates (dual RTBV-RTSV infections) at sample dilution of 1:10, IgGB4b and IgGB6b for RTBV and IgGS3 and IgGS6b for RTSV performed equally well. However, after cross adsorption with healthy plant extracts in a specially prepared healthy plant-Sepharose affinity column, only IgGB6b could be used specifically to detect RTBV in a simple tissue-print assay.     

Is it worthy to take full-course immunotherapy for allergic rhinitis? About efficacy biomarker of allergen immunotherapy

Nowadays, people pay more attention to biomarkers that can predict clinical efficacy of immunotherapy for allergic rhinitis. As the only recognized aetiological treatment, the efficacy of allergen immunotherapy (AIT) has been proved by many studies. However, treatment success depends on compliance and persistence greatly, which can be impaired by the lengthy duration of AIT and socioeconomic status of patients. Besides, ineffectiveness is another factor that accounts for non-adherence. If the clinical efficacy can be predicted in the early stage of immunotherapy, it can help patients choose appropriate treatment plans, increase patient compliance and optimize the allocation of medical resources. This paper mainly focuses on five candidate biomarkers, the sIgE/tIgE ratio before treatment, serum inhibitory activity for IgE, decreased basophil activation, upregulation of Tregs and tolerogenic DCs, reviews the time when potential biomarkers can predict or monitor the efficacy of AIT, discusses the reason why these indicators could serve as efficacy biomarkers and interactions among potential biomarkers.     

Neurotransmitter signaling pathways required for normal development in Xenopus laevis embryos: a pharmacological survey screen

Neurotransmitters are not only involved in brain function but are also important signaling molecules for many diverse cell types. Neurotransmitters are widely conserved, from evolutionarily ancient organisms lacking nervous systems through man. Here, results are reported from a loss‐ and gain‐of‐function survey, using pharmacological modulators of several neurotransmitter pathways to examine possible roles for these pathways in normal embryogenesis. Applying reagents targeting the glutamatergic, adrenergic and dopaminergic pathways to embryos of Xenopus laevis from gastrulation to organogenesis stages, we observed and quantified numerous malformations, including craniofacial defects, hyperpigmentation, muscle mispatterning and miscoiling of the gut. These data implicate several key neurotransmitters in new embryonic patterning roles, reveal novel earlier stages for processes involved in eye development, suggest new targets for subsequent molecular‐genetic investigation, and highlight the necessity for in‐depth toxicology studies of psychoactive compounds to which human embryos might be exposed during pregnancy.     

HLA genes in Amerindians from Mexico San Vicente Tancuayalab Teenek/Huastecos

Huastecos or Teenek Amerindians are presently living at North East Mexico (San Luis Potosi State). They have probably one of the most ancient culture of Mexico and Central America together with Mayas and Olmec groups with which also show close relationships. Proximity to Atlantic Ocean/Mexican Gulf originated that Spaniards had very early contact with them at about 1519 CE or before. In the present paper we have aimed to study HLA gene profile which may be useful for HLA and disease epidemiology and transplant programs in Teeneks. HLA-DRB1*04:07, -DRB1*14:06 and -DRB1*04:11 have been found in high frequency like in other Amerindian groups. High frequency typical Amerindians HLA extended haplotypes have been found, such as A*02-B*35-DRB1*04:07-DQB1*03:02; A*68-B*39-DRB1*04:07-DQB1*03:02 and A*02-B*39-DRB1*04:07-DQB1*03:02; also new haplotypes have been described, like A*02-B*52-DRB1*04:11-DQB1*03:02, A*68-B*35-DRB1*14:02-DQB1*03:01 and A*68-B*40-DRB1*16:02-DQB1*03:01. Genetic proximity is observed not only to linguistically close Mayans, but also to Mazatecans, Mixtecans and Zapotecans, who speak an altogether different languages; it shows once more that genes and languages do not correlate. This population was greatly diminished after European contact between 1500 and 1600 years CE; in fact, North and South America First Inhabitants population was brought from 80 down to 8 million people because of diseases (i.e.: measles, smallpox or influenza), slavery and war.