膝骨关节炎女性伸膝肌力、步态时空参数与峰值膝关节屈曲/内收力矩关系

背景：已有研究表明膝骨关节炎患者的膝关节力矩会发生改变，但对于力矩变化与伸膝肌力及步态时空参数之间的相关性报道较少。目的：探索女性膝骨关节炎患者伸膝肌力及步态时空参数与峰值膝关节屈曲/内收力矩之间的相关性。方法：选取2022年2-8月在北京积水潭医院贵州医院住院治疗的20例单膝患病女性膝骨关节炎患者作为膝骨关节炎组，另外选取20例无肌肉骨骼疾病的女性健康人作为对照组。利用Biodex等速仪测量60 (°)/s向心伸膝肌力，并采用意大利BTS红外运动捕捉系统和测力台采集步态时空参数和峰值膝关节屈曲力矩和膝关节内收力矩。通过Pearson相关性分析探索肌力、步态时空参数和峰值膝关节内收力矩和膝关节屈曲力矩的关联，并进一步将与膝关节力矩显著相关的变量纳入多元逐步回归分析。结果与结论：(1)与对照组相比，膝骨关节炎组60 (°)/s向心伸膝肌力、步速、步频、步长以及峰值膝关节屈曲力矩均更低(P <0.05)；(2)Pearson相关性分析结果显示60 (°)/s向心伸膝肌力、步速、步频、步长与峰值膝关节屈曲力矩呈正相关，与峰值膝关节内收力矩呈负相关，差异有显著性意义(P <0.05...     

内侧半月板损伤患者关节镜手术前后三维步态特征差异

目的比较膝关节内侧半月板损伤患者关节镜手术前后的三维步态特征。方法纳入15名内侧半月板损伤患者和15名健康人群作为研究对象,采集损伤组术前、术后及健康对照组的三维步态参数,包括步态时空参数、运动学以及动力学参数。结果 (1)损伤组术前步速和步长与对照组相比显著下降(P0.05),损伤组术后步速、步长与对照组相比无显著差异。(2)矢状面,损伤组术前膝关节屈曲伸展活动范围、承重反应期和摆动相膝关节最大弯曲度较对照组显著下降(P0.001);术后承重反应期膝关节弯曲度较术前明显增加(P0.05),但术后摆动相膝关节最大弯曲角度和屈曲伸展活动范围仍显著低于对照组(P0.05)。冠状面,损伤组术前内收外展活动范围和最大内收角度较对照组显著下降(P0.001);术后内收外展活动范围和最大内收角度较术前显著增加(P0.05),但也显著低于对照组(P0.001)。(3)矢状面,损伤组术后膝关节屈曲力矩第1、第2峰值较术前增加(P0.05),但仍显著低于对照组(P0.05)。冠状面,损伤组术后内收力矩第1、第2峰值较术前增加,但也显著低于对照组(P0.05)。结论半月板损伤患者有其独特的步态特征,通常采取僵硬步态来降低膝关节负荷。关节镜下半月板成形术能显著改善膝关节步态特征,但患者步态仍不能在短期内恢复正常。     

不同速度下正常老年人下肢关节的角度参数

背景：目前国内主要采用步态分析仪测量患者步行时的关节角度,但是在每一个康复治疗时期进行这些测量非常耗费时间。利用Lokomat步态康复机器人则可以在患者训练过程中对患者的关节角度、肌力等参数进行实时记录,省时省力。 目的：采用步态康复机器人Lokomat测定正常老年人不同速度下的下肢关节角度参数。 方法：选取健康老年人30名,男15名,女15名,年龄60~64(62.40±1.58)岁。利用步态康复机器人评估工具,在减重40%,引导力60%,速度1.6,1.8,2.0 km/h状态下对正常老年人的下肢关节角度参数进行记录。 结果与结论：老年人关节角度参数动态指标测试结果显示,在速度1.6 km/h状态下左髋关节最大伸展角度,在速度2.0 km/h状态下左、右髋关节最大屈曲角度,男女组间差异有显著性意义(P < 0.05)。老年人不同速度下髋膝关节角度测试结果显示,老年人左右膝关节最大伸展角度在步行速度1.6 km/h与1.8 km/h,1.6 km/h与2.0 km/h,1.8 km/h与2.0 km/h相比差异有显著性意义(P < 0.05)。结果可见不同速度下髋关节最大屈曲角度男性大于女性,治疗师在进行Lokomat步态康复训练时应根据患者的性别差异,调整髋膝关节角度和训练模式。随着步行速度的增加老年人髋膝关节屈曲角度增加,伸展角度减小,治疗师应根据步速的增减适当调节髋膝关节活动度,增强患者腿部运动与机器人外骨骼式机械腿的配合,提高患者的训练效果。     

骨水泥型与非骨水泥型全膝关节置换后的步态差异

背景：全膝关节置换已经被证明是一种有效治疗膝骨性关节炎的方法,但是不同类型的全膝关节置换假体固定方式术后所产生的膝关节下肢生物力学差异至今仍不明确。 目的：通过三维步态分析骨水泥固定和非骨水泥固定两种不同的全膝关节置换术后患者的膝关节生物力学差异。 方法：分别选取骨水泥型全膝关节置换以及非骨水泥型全膝关节置换患者各16例,通过测力台以及三维步态分析系统比较2组患者术前以及术后3个月的膝关节生物力学变化并进行对比。 结果与结论：与手术前相比两组患者术后步速及步长均明显增加,支撑相在整个步态周期中的百分比明显减小, 膝关节屈在支撑相及摆动相中最大屈曲角度均明显增加,膝关节外翻角度增加。两种患者术后膝关节内翻角度以及膝关节内收力矩均明显减小。提示,骨水泥型与非骨水泥型全膝关节置换术均能有效改善膝骨性关节炎患者的步行能力以及下肢关节功能,两者间未见明显生物力学差异。     

全膝关节置换术后早期步态与预后功能的相关性分析

目的探讨全膝关节置换(total knee arthroplasty, TKA)术后14 d步态参数与术后3个月膝关节功能和生活质量的相关性。方法采用三维步态系统分析18名患者TKA术后14 d患侧步行特征,运用WOMAC和SF-36评价量表评估患者TKA术后3个月的膝关节功能指数及生活质量并分析其相关性。结果 TKA术后14 d,术侧单支撑时间和摆动期膝关节屈角峰值均显著小于健侧,术侧站立中期膝关节屈角和膝外翻角均显著大于健侧;步行过程中,术侧的时空参数指标与WOMAC评分存在中度负相关,膝屈角峰值、站立中期膝屈角及外翻角与WOMAC评分存在高度相关性;除步长、步速外,其余步态参数指标均与SF-36生活质量评分具有显著相关性。其中,单支撑时间和膝关节屈角峰值具有高度正相关,站立中期膝屈角及外翻角具有中度负相关。结论术后早期(14 d)步态分析结果中术侧单支撑时间、站立中期膝关节屈角、膝外翻角及摆动期膝关节屈角峰值可以作为判断TKA手术预后膝关节功能及生活质量康复疗效的有效指标。     

同期双侧全膝关节置换与选择性单侧全膝关节置换后的早期功能恢复

背景：同期双侧全膝关节置换与选择性单侧全膝关节置换后的早期功能恢复一直存在着争议。 目的：评价双膝骨关节炎患者同期双侧全膝关节置换与选择性单侧全膝关节置换后功能恢复情况的差异。 方法：根据置换方案将初次行全膝关节置换的双膝骨关节炎患者86例(116膝)分为两组,双膝组(n=29,58膝)行同期双侧全膝关节置换,单膝组(n =57,57膝)行单侧全膝关节置换。分别对两组患者置换前后的关节活动度、屈曲挛缩度、肌力、疼痛评分、双下肢不等长及HSS评分进行比较分析,并记录并发症的发生率。 结果与结论：置换后1年随访,两组患者置换后关节活动度和肌力差异无显著性意义(P=0.171,0.418);置换后屈曲挛缩度、疼痛评分及双下肢不等长双膝组均显著低于单膝组(P=0.006,0.0013,0.026);同时双膝组置换后HSS评分优于单膝组(P=0.003)。提示同期双侧全膝关节置换患者在屈曲挛缩度、疼痛症状评分、双下肢不等长及HSS评分方面优于单侧全膝关节置换,而两种方案在置换后关节活动度和下肢肌力方面无明显差异。     

不同躯干约束下蹲姿对人体下肢运动学和动力学的影响

目的 探究躯干控制对青年群体亚洲蹲和西方蹲时下肢运动生物力学特征的影响,为深蹲训练的应用和推广提供实证性依据。方法 24名健康男性青年大学生在带杆、无杆控制条件下进行亚洲蹲和西方蹲,运用红外光点运动捕捉系统和三维测力台采集其下肢运动学和动力学特征。通过Cortex-642.6.2软件,根据欧拉角方法计算获得下肢三维角度,运用逆动力学方法得到三维力矩。通过2×2重复设计的双因素方差分析检验躯干控制和深蹲姿势对下肢运动特征的影响。结果 躯干控制和深蹲姿势对运动学和动力学参数均无显著性交互作用(P>0.05)。西方蹲具有较大的膝关节屈曲角、髌股关节接触力峰值、髋膝伸展力矩峰值之比,较小的踝关节背屈角、髋关节屈曲角(P<0.05)。带杆深蹲具有较大的踝关节背屈角、髌股关节接触力峰值和髋关节屈曲角,较小的膝关节屈曲角、髋膝伸展力矩峰值之比(P<0.05)。结论 西方蹲有助于训练伸髋肌群肌力,亚洲蹲则有助于训练伸膝肌群肌力。西方蹲髌股关节接触力峰值显著大于亚洲蹲,故推荐髌股关节痛患者采用亚洲蹲。带杆深蹲可补偿人体平衡,建议由于踝关节背屈活动范围受限或胫骨前肌无力人群可以考虑进行带...     

膝骨性关节炎合并内翻畸形患者运动特征研究

为研究膝骨性关节炎合并内翻畸形患者术前生物力学群体特征,用于比较患者术前术后步态延续性及进行术后康复指导,本文采集9例患者水平行走和坐立-起身过程的步态,并进行骨肌多体动力学分析。本文研究结果显示,水平行走时试验组下肢运动功能减弱,试验组非手术侧膝关节平均活动范围为22.5°~71.5°,拟置换侧膝关节平均活动范围为24.4°~57.6°,而对照组膝关节平均活动范围为7.2°~62.4°。单侧膝内翻患者完成坐立-起身过程时的下肢地面反作用力对称度介于0.72~0.85,非手术侧下肢起主要支撑作用。双侧膝内翻患者坐立-起身时地面反作用力之和最小。尽管单侧膝内翻患者采用非手术侧下肢过量负载的代偿方式能完成术后日常活动,但长期过量负载容易增加非手术侧下肢膝关节罹患膝骨性关节炎风险。对膝骨性关节炎合并内翻畸形患者完成日常活动的运动学和生物力学特征进行研究,有助于从生物力学角度理解内翻膝的发病机制,对患者的术前评估、预防和术后恢复具有较强的临床指导意义。     

股骨内翻和胫骨内翻的运动学和足底压力分析

目的 探究胫骨侧和股骨侧来源的两种单侧膝骨关节炎膝内翻在步态分析中的运动学参数和足底压力差异,为不同类型膝内翻提供生物力学理论基础。方法 招募26名单侧膝骨关节炎型膝内翻患者,股骨侧和胫骨侧来源各13名受试者。利用Noraxon MyoMotion三维动作捕捉系统和Footscan平板式足底压力测试系统,测量受试者在自然行走状态下的步态,采集受试者步态的时空指标、下肢各关节运动学参数、足底压力,并进行两组间对比分析。结果 胫骨侧膝内翻的膝关节屈伸范围、髋关节外展峰值、髋关节内收外展活动范围、踝关节内旋峰值均大于股骨侧膝内翻,而膝关节屈曲峰值、髋关节内收峰值小于股骨侧膝内翻;与股骨侧膝内翻相比,胫骨侧膝内翻受试者第4、5跖骨足底受力时间、压力峰值都增加(P<0.05)。在第3跖骨区域中,股骨健侧肢体比胫骨畸形健侧肢体的冲量更大;而在足跟内侧区域,股骨健侧肢体的冲量更小(P<0.05)。结论 两种不同类型单侧膝内翻患者在运动学参数和足底压力方面存在一定差异。研究结果有助于正确认识膝内翻引起的异常步态,为不同类型膝内翻诊治、术后康复和肢体锻炼提供可靠参考。     

痉挛型脑瘫患者功能性选择性脊神经后根切断术前后的三维步态特征分析

目的分析痉挛型脑瘫患者功能性选择性脊神经后根切断(functional selective posterior rhizotomy,FSPR)手术前后的步态特征,客观量化评估手术疗效。方法选取15名将要进行FSPR手术治疗的痉挛型脑瘫患者,应用VICON三维运动捕捉系统结合AMTI三维测力台对患者进行手术前后的步态采集,分析手术前后步态的时空、运动学及动力学参数。结果手术后,左、右支撑时间均大于手术前,左侧步长明显大于手术前,步高、步速及冠状面重心偏移均小于手术前;着地时的膝关节矢状面角度(即屈伸角度)出现明显提高,髋、踝关节未见明显差异。手术后,步行过程中左右侧髋、膝、踝关节活动范围(range of motion,ROM)在矢状面均出现不同程度的提高,且有统计学差异;右踝关节冠状面ROM也出现明显提高。手术后,右膝关节最小屈曲角度及左、右踝关节最大跖屈角度均出现显著减小;左、右侧支撑相最大垂直力较手术前明显提高,而下肢关节力矩未见明显差异。结论三维步态分析可以在一定程度上评估痉挛型脑瘫患者FSPR手术的疗效。术后痉挛型脑瘫患者的痉挛得到缓解,对步态的时空参数及下肢关节运动学参数改善比较明显,而对于动力学参数改善相对不明显,需进行进一步康复治疗。     

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 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.     

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.     

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.     

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.     

'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 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.     

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.