类风关滑膜浸润T细胞特性与致病机制研究

为研究类风湿关节炎时关节滑膜浸润性T细胞生物学特性与致病机制 ,对 10例RA患者滑膜液中淋巴细胞的免疫表型、细胞因子分泌格局与趋化因子受体表达进行了分析。用双色荧光标记法分别测定滑膜液中和外周血淋巴细胞表型与趋化因子受体表达。用ELISA方法检测滑膜液与外周血中IFN γ、IL 10、IL 4与IL 12的含量。结果是滑膜液中的CD4 + T淋巴细胞为 4 0 0 %± 11% ,CD8+ T细胞为 34 0 %± 6 % ,CD4 + 与CD8+ T细胞的比值为 1 2 ,显著低于外周血中CD4 /CD8的比值。滑膜液中CD3和CD2 5双阳性的活化T细胞占 16 %± 6 0 %。趋化因子受体CCR5表达较低 ,与外周血无明显差异。但CX CR3表达水平较高 ,为 16 %± 4 0 % ,远远高于外周血 (仅为 0 5 %± 0 3% )。IFN γ在滑膜液中含量很高 ,达 (36 6 7± 4 3 2 )pg/ml,而外周血中含量仅为 (2 0 1± 3 2 )pg/ml。IL 4含量未能测得 (<15pg/ml ) ,与外周血相似。IL 12含量为 (4 19 9±89 2 )pg/ml,远高于外周血中的含量 (6 5 32± 34 2 )pg/ml。IL 10含量为 (187 7± 34 5 )pg/ml,高于外周血中的含量 (85±12 7)pg/ml。在所测细胞因子中 ,关节滑膜液中IFN γ和IL 12的含量与外周血相比具有显著的统计学差异。表明RA关节滑膜液中有相当数量的T细胞浸润。这些T细胞     

骨关节炎与免疫关联性初探

为了探讨免疫因素是否介导骨关节炎的发病 ,应用直接免疫荧光法检测了 6例晚期骨关节炎患者滑膜液中浸润淋巴细胞分化抗原的表达 ,同时用微量酶联免疫技术测定了这些患者滑膜液中IL 10、IL 12和sFasL的含量。结果显示关节滑膜液中的淋巴细胞以CD8+ 细胞为主 (6 7 0 %± 14 6 %) ,远远高于CD4+ 细胞 (15 0 %± 12 8%) ,两者相差显著 (P <0 0 1)。CD4+ /CD8+ 比值 <1。进一步分析表明其T细胞受体主要为αβ型TCR (6 4 0 %± 12 6 %)。滑膜液中IL 12含量 (2 0 3 84±49 2 )pg/ml高于IL 10 (37 8± 14 5 )pg/ml,有明显统计学差异 (P <0 0 1)。外周血中IL 10和IL 12的含量分别为 (4 3 37±14 2 )pg/ml和 (4 5 5 8± 10 6 )pg/ml。血清中sFasL含量较高 (15 3 90± 5 6 )pg/ml,而滑膜液中则很低 (<5pg/ml,P <0 0 1)。提示在骨关节炎的晚期CD8+ 淋巴细胞和IL 12增高可能参与了关节的免疫损伤。     

类风湿性关节炎患者滑膜液中IL-10、IL-12和sFasL含量的检测

为了研究细胞因子和凋亡分子在类风湿性关节炎(RA)发病中的作用,用ELISA法分析了26例RA患者滑膜液和血清中IL-12、IL-10和可溶性FasL(sFasL)的含量。结果表明RA患者滑膜液中IL-12、IL-10含量分别为(419.9±89.2)pg/ml和(187.7±34.5)pg/ml,外周血中这两种细胞因子的含量均较低,分别为(65.3±34.2)pg/ml(IL-12)和(85.0±12.7)pg/ml(IL-10)。滑膜液中sFasL的含量为266pg/ml,明显高于血清含量(36pg/ml)。这一结果提示,RA患者滑膜液中IL-12含量和sFasL增高,这些炎性细胞因子增高可能参与了关节滑膜中的自身反应性T细胞的活化,继而造成免疫损伤。     

类风湿性关节炎活动期外周血CT4+T细胞的表型变化

目的观察类风湿性关节炎(RA)活动期外周血CT4+T淋巴细胞的表型变化,探讨其免疫病理机制。方法采用ELISA和双标记免疫荧光法检测50例活动期RA患者和50例健康成人外周血CD4+T细胞表面CD154、CD69的表达以及血清、血浆可溶性CD154(sCD154)的含量。结果活动期RA患者的外周血CD4+T细胞CD154(16.8%±7.9%)和CD69(14.1%±8.2%)的表达水平均显著高于健康人,其血清sCD154(18.56±6.32,ng/ml)和血浆sCD154(8.41±3.51,ng/ml)含量亦分别高于健康人血清sCD154(9.56±4.71,ng/ml)和血浆sCD154(2.98±1.13,ng/ml)。结论CD4+T细胞表达的CD154、CD69以及血浆sCD154含量与RA的活动相关,可以作为RA的辅助诊断、疗效评价和预后判断的有价值的实验室参数。     

慢性乙型病毒性肝炎患者外周血T淋巴细胞CD27和CD45RA表达的研究

目的分析慢性乙型病毒性肝炎患者外周血T淋巴细胞CD27和CD45RA的表达。方法采集分离健康人和慢性乙型病毒性肝炎患者外周血单个核细胞(PBMC),利用多种荧光标记抗体标记细胞表面分子,再用流式细胞仪检测CD8+T淋巴细胞表面CD27和CD45RA表达情况。结果31例慢性乙型病毒性肝炎患者CD8+CD45RA+CD27+T细胞占CD8+T细胞(29.03±13.18)%,低于28例健康对照组的(60.85±14.36)%,P<0.01。而CD8+CD45RA-CD27+T细胞占CD8+T细胞(30.31±24.11)%,显著高于健康对照组的(10.32±5.24)%,P<0.05。慢性乙型病毒性肝炎患者CD4+CD45RA+CD27+T细胞21.12±9.64%低于健康对照组的(60.89±17.93)%,P<0.01,而CD4+CD45RA-CD27+T细胞(54.28±18.75)%显著高于健康对照组的(27.16±9.24)%,P<0.01。结论健康人外周血CD8+和CD4+T淋巴细胞均以CD45RA+CD27+初始细胞表型为主,而慢性乙型病毒性肝炎患者外周血初始细胞减少,CD45RA-CD27+表型的T淋巴细胞明显增加。     

类风湿关节炎CD4+CD28-T细胞与淋巴细胞凋亡的相关性研究

目的: 研究类风湿关节炎(RA)患者外周血CD4⁺CD28^-T细胞比例与淋巴细胞凋亡异常的相关性。方法: 采用流式细胞术三色分析法检测50例患者和50例健康志愿者的外周血淋巴细胞中CD4⁺CD28^-T细胞比例;通过加入PHA孵育检测RA病人外周淋巴细胞和正常对照的淋巴细胞对激活诱导细胞死亡(AICD)易感性差异;分析CD4⁺CD28^-T细胞比例与外周血淋巴细胞凋亡率的相关性。结果: RA组CD4⁺CD28^-T细胞比例的均数明显高于健康对照组(7.79%±3.52% vs 1.89%±1.78%,P<0.05)。RA组病人外周血淋巴细胞的AICD凋亡率低于健康对照组(11.38%±5.73% vs 19.46%±6.32%,P<0.05)。Spearman相关分析结果显示CD4⁺CD28^-T细胞比例与外周血淋巴细胞AICD凋亡率负相关(r=-0.433,P<0.01)。结论: RA患者外周血中CD4⁺CD28^-T细胞比例增多,活化淋巴细胞生存期延长,这可能参与RA的发病机制。     

HLA-DRB1*07与慢性乙肝患者Th1/Th2因子表达水平的相关性

目的 :探讨广东地区汉族慢性乙型肝炎患者HLA DRB1 0 7与Th1 Th2因子表达水平的相关性。方法 :收集 12 0例广东地区汉族慢性乙肝患者新鲜抗凝血各 8ml,通过序列特异性引物套式PCR(PCR SSP)方法进行HLA DRB1 0 7检测 ,并同时用双抗体夹心法检测患者治疗前后外周血CD4 +T细胞分泌IFN γ、IL 2、IL 10和IL 4的水平。结果 :12 0例慢性乙肝患者HLA DRB1 0 7携带者 31例 ,携带率为 2 5 8% ,明显高于广东地区汉族人群的平均携带率 7 84 % ;HLA DRB1 0 7阳性患者IFN γ平均表达水平为 (1132 0 4± 75 36 )pg ml,IL 2平均表达水平为 (1184 0 6± 81 4 2 )pg ml,IL 4平均表达水平为 (876 79± 4 7 5 3)pg ml,IL 10平均表达水平为 (817 4 8± 2 4 4 0 )pg ml ;HLA DRB1 0 7阴性患者IFN γ平均表达水平为 (12 32 10± 198 13)pg ml,IL 2平均表达水平为 (12 0 8 17± 116 12 )pg ml,IL 4平均表达水平为 (6 81 99± 6 1 5 9)pg ml,IL 10平均表达水平为 (6 38 84± 76 17)pg ml。HLA DRB1 0 7阳性患者IL 4、IL 10表达水平高于阴性患者 (P <0 0 5 ) ,而IFN γ、IL 2表达水平与阴性患者差异无统计学意义 (P >0 0 5 )。结论 :HLA DRB1 0 7(+)慢性乙肝患者Th2因子表达水平高于HLA DRB1 0 7(- )慢性乙肝患者。     

类风湿关节炎患者外周血和滑液中CD4~+CD25~+调节性T细胞的水平变化

了解具有抑制功能的CD4+CD25+调节性T细胞(Treg)在类风湿关节炎(RA)中的水平变化。分离32例RA患者及35例正常对照者外周血和15例RA关节滑液中的单个核细胞,用荧光抗体标记细胞膜表面CD4、CD25分子和细胞内Foxp3转录因子,进行流式细胞分析,同时用RT-PCR方法测定单个核细胞中Foxp3 mRNA水平。实验发现RA外周血中CD4+CD25hT细胞比例(1.90±1.68)与健康人(1.81±1.79)无明显差异,而RA关节滑液中CD4+CD25+和CD4+CD25hT细胞含量却明显增高(14.98±12.52,8.94±9.67,P<0.01)。RA患者外周血单个核细胞中Foxp3+/CD4+T细胞比值(2.35±2.06)较正常人(7.25±3.98)明显降低(P<0.01),RA外周血中Foxp3 mRNA含量较正常人Treg减少,而RA关节液中Foxp3 mRNA含量较RA外周血更为低下(P<0.01)。RA患者存在CD4+CD25+Treg的异常改变,其外周血和关节液中具有抑制作用的Treg含量明显降低提示RA患者Treg数量减少及抑制功能下降可能是RA自身免疫反应亢强不能控制的原因之一。RA关节液中CD4+CD25hT细胞增高考虑与RA炎症反应造成T细胞过度活化有关。     

骨髓间充质干细胞对异体T细胞几种细胞因子分泌的影响

目的:探讨骨髓间充质干细胞(MSC)对异体T淋巴细胞分泌IL-2、IL-4、IL-10、IFN-γ的影响,从而进一步探讨MSC诱导免疫耐受的机制。方法:将培养了3代后的MSC经照射后作为基底层细胞,接种分离的异体T淋巴细胞。共培养7天后,用ELASA方法检测上清中的上述四种细胞因子的蛋白含量,同时计数T淋巴细胞数量的变化,应用流式细胞仪检测与MSC共孵育前后T淋巴细胞CD3、CD4、CD8、CD25的变化。结果:(1)ELASA检测IFN-γ分泌量为667·07±14·76pg/ml;IL-10为46·19±1·41pg/ml;IL-2为33·01±5·92pg/ml;IL-4为0·15pg/ml。(2)共孵育组T淋巴细胞在数量上明显减少。(3)CD8+细胞数增多,CD25+细胞减少。结论:骨髓MSC在体外与异体T淋巴细胞共孵育后IFN-γ高分泌,可能与共孵育后T淋巴细胞亚群的改变有关。这一研究结果为预防HLA不相合的骨髓移植的GVHD的发生提供了一条新的思路。     

流式细胞术检测淋巴细胞增殖方法的建立

目的 :建立一种用流式细胞仪同时测定T淋巴细胞增殖与细胞因子分泌的方法。方法 :用非特异性刺激剂PMA、PHA刺激 1 0例正常人外周血单个核细胞 ,体外培养 2、4、6、8、1 0h ,流式细胞术在单细胞水平检测T淋巴细胞的功能性激活、表面活化标志性抗原 (CD69)的表达、DNA合成 (BrdU掺入法 )及胞内细胞因子 (IL 4、IFN γ)分泌。选择合适的刺激剂、调整细胞浓度、优化实验方法 ,确定最佳实验条件。结果 :BrdU掺入法测定T淋巴细胞增殖 ,最佳的反应细胞浓度为 1× 1 0 6ml-1 ,比较不同刺激剂和体外培养时间 :PMA(2 0ng ml)刺激后 8hT细胞中CD69+、BrdU+双阳性细胞比例最高 (82 3 %± 7 2 % ) ,IFN γ+、IL 4+细胞百分率分别为 2 5 2 %± 3 7%和 3 4%± 1 6 % ,均显著高于未刺激组 (P <0 0 1 )。结论 :应用流式细胞术进行单个核细胞的增殖分析可以同时检测细胞表面活化抗原的表达、DNA合成及胞内细胞因子的分泌。此方法能够分析不同亚群细胞对于不同刺激原的反应和激活表型。敏感性高、重复性好 ,可在单细胞水平检测单个核细胞的增殖和功能性激活     

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.