CPZ介导急性脱髓鞘小鼠海马中nestin的表达

目的:探讨双环己酮草酰二腙(cuprizone,CPZ)介导急性脱髓鞘小鼠海马中nestin的表达。方法:用掺入0.2%CPZ的普通饲料饲养C57BL/6小鼠6周,制备脱髓鞘模型,然后使用免疫荧光染色、q RT-PCR、Western Blot方法,检测小鼠脑内髓鞘脱失后海马中nestin的表达变化。结果:(1)体重称量结果显示:CPZ组体重明显低于对照组(P0.01);(2)免疫荧光结果显示:CPZ组海马CA区和DG区颗粒细胞层中nestin阳性细胞明显低于对照组分别为:P0.05,P0.01;(3)Western Blot和q RT-PCR实验结果显示:CPZ组海马中nestin蛋白和m RNA含量均明显低于对照组(P0.05)。结论:CPZ介导小鼠急性脱髓鞘后海马内nestin表达降低,提示髓鞘脱失可能会抑制nestin表达。     

神经调节蛋白1及其受体ErbB4在精神分裂症小鼠前额叶皮质中的表达变化

目的:探讨精神分裂症神经调节蛋白1(NRG-1)及其受体(ErbB4)与少突胶质细胞脱髓鞘和髓鞘再生之间的关系。方法:采用双环己酮草酰二腙(CPZ)诱导的少突胶质细胞脱髓鞘制备精神分裂症小鼠动物模型。动物分为6组,对照组(食物中未添加CPZ),CPZ喂养2周、3周、4周组,第4周后停止给予CPZ,继续正常喂养1周即5周组;停止给予CPZ后,继续正常喂养2周即6周组。通过实时定量PCR及免疫印迹检测,观察NRG-1和ErbB4在小鼠大脑额叶脱髓鞘和髓鞘再生过程中的表达变化。结果:NRG-1 mRNA和蛋白的表达在第2周、第3周和第4周CPZ组较对照组、第5周和第6周明显降低。ErbB4 mRNA和蛋白的表达在各组与对照组比较均增强。ErbB4在第5周和第6周mRNA和蛋白的表达明显高于第2周、第3周和第4周CPZ组。结论:在小鼠精神分裂症形成过程中,NRG-1和ErbB4的表达变化与少突胶质细胞的脱髓鞘和髓鞘再生有关系。     

肌苷对CPZ介导的急性脱髓鞘小鼠行为学及皮质髓鞘的影响

目的:探讨肌苷对双环己酮草酰二腙(cuprizone,CPZ)介导的急性脱髓鞘小鼠行为学及皮质髓鞘的影响。方法:在普通饲料中掺入0.2%CPZ,饲养小鼠6 w,同时联合腹腔注射肌苷,制备脱髓鞘治疗模型,利用体重测量、Morris水迷宫、悬尾实验、透射电镜等技术,观察肌苷对脱髓鞘小鼠治疗后行为学及皮质髓鞘的影响。结果:(1)体重变化:与生理盐水对照组比较,CPZ损伤组、肌苷治疗组小鼠体重从第6 d开始均明显降低(P0.05);(2)行为学:Morris水迷宫空间定位实验中,与CPZ损伤组比较,肌苷治疗组平台象限停留时间明显增加(P0.05);悬尾实验中,小鼠6 min不动时间均无明显差异(P0.05);(3)皮质髓鞘电镜观察显示,肌苷治疗组小鼠的皮质髓鞘病理改变程度降低,有新生髓鞘。结论:通过含0.2%CPZ饲料饲养联合腹腔注射肌苷制备脱髓鞘治疗小鼠,可使小鼠的学习、记忆功能明显改善,皮质髓鞘有明显的修复与再生,揭示肌苷对伴有学习记忆功能障碍的脱髓鞘小鼠有髓鞘保护作用。     

急性脱髓鞘对小鼠海马和大脑皮层中Nkx2.2的影响

目的:探讨双环己酮草酰二腙(CPZ)诱导急性脱髓鞘后小鼠认知功能的改变,以及海马和大脑皮层中Nkx2.2同源域转录因子(Nkx2.2)的表达变化,并探讨两种变化之间的关系。方法:0.2%CPZ喂养ICR小鼠6周建立急性脱髓鞘模型。通过Morris水迷宫(MWM)和悬尾实验(TST)检测CPZ介导的急性脱髓鞘后小鼠行为学的改变; Western Blot检测脱髓鞘后小鼠海马和大脑皮层中髓鞘碱性蛋白(MBP)和Nkx2.2蛋白的表达;免疫组织化学检测CPZ脱髓鞘后小鼠海马和大脑皮层中Nkx2.2的表达变化。结果:MWM和TST结果显示:与对照组小鼠相比,CPZ组小鼠MWM实验中的逃避潜伏期时间增加,穿越平台次数减少,TST的悬尾不动时间增加(P 0.05); Western Blot结果显示:CPZ组小鼠海马和大脑皮层中的MBP蛋白含量均明显低于对照组(P 0.05),Nkx2.2蛋白含量均明显高于对照组(P 0.05);免疫组织化学结果显示:CPZ组小鼠海马和大脑皮层中Nkx2.2的免疫阳性表达均高于对照组(P 0.05)。结论:CPZ介导急性脱髓鞘后小鼠的认知功能下降,海马和大脑皮层中Nkx2.2的表达增加,提示Nkx2.2在脱髓鞘模型中的异常增加可能是导致小鼠认知功能下降的原因之一。     

miR-30a对实验性自身免疫性脑脊髓炎模型小鼠发病的作用

目的:探讨在体过表达miR-30a对实验性自身免疫性脑脊髓炎(EAE)模型小鼠脱髓鞘病变的作用。方法:构建含稳定表达miR-30a的shRNA慢病毒载体,以含有空载体的慢病毒为对照(LV-ctrl)。雌性C57BL/6小鼠随机分为正常对照组(normal)、对照慢病毒(LV-ctrl)组和miR-30a慢病毒(LV-miR-30a)组,2组慢病毒经尾静脉注射,注射7 d后用MOG35-55多肽免疫小鼠。Kono 5分法检测发病情况,快蓝(LFB)染色及透射电镜检测脊髓脱髓鞘程度及髓鞘结构的变化。结果:LV-ctrl组小鼠在MOG_(35-55)多肽免疫的第10天开始发病,到第21天,其Kono评分为2.57±0.79,LV-miR-30a组小鼠的Kono评分显著低于LV-ctrl组小鼠;miR-30a处理可显著提高小鼠体质量增长率,同时LFB评分也较LV-ctrl组显著增加;髓鞘超微结构显示LV-ctrl组小鼠脊髓髓鞘板层松解且稀疏,而LV-miR-30a组小鼠的髓鞘结构相对完好,髓鞘厚度显著大于LV-ctrl组。结论:过表达miR-30a可以明显减缓EAE的发病,减轻脊髓脱髓鞘程度。     

髓鞘形成相关NMDA-R亚基在精神分裂症小鼠模型中的变化

目的:探讨髓鞘形成相关N-甲基-D-天冬氨酸受体(NMDA-R)亚基在MK-801诱导的精神分裂症小鼠模型大脑中的变化。方法:35只雄性C57BL/6J小鼠,随机分为:对照组(control)和地卓西平马来酸盐处理组(MK-801),利用旷场实验、探孔实验及高架十字迷宫检测小鼠行为学改变,免疫荧光染色观察小鼠大脑NMDAR亚基NR1的表达,real time RT-PCR检测髓鞘形成相关NMDA-R亚基NR1、NR2C和NR3A mRNA的表达。结果:与对照组小鼠相比,MK-801处理组在旷场内10 min总运动路程较对照组显著增加;3 min及5 min内探孔次数较对照组显著降低;模型组小鼠在开臂内停留总时间较对照组显著降低。NR1在小鼠神经细胞胞膜、轴突周围和髓鞘部位均有表达。大脑皮层、海马内的NMDA-R亚基NR1,NR2C及NR3A mRNA的表达在两组间均无显著差异;胼胝体区域NR1和NR2C mRNA表达在两组间同样无显著差异;但相较于对照组,MK-801慢性给药组小鼠胼胝体区域NMDA-R亚基NR3A mRNA表达显著上调。结论:NMDA-R在少突胶质细胞、髓鞘等部位确有表达;胼胝体部位NR3A亚基上调可能在MK-801诱导的精神分裂症中发挥作用。     

两类抗精神病药对脱髓鞘小鼠模型髓鞘修复的影响

目的:探讨抗精神病药物对双环己酮草酰二腙(CPZ)诱导的慢性脱髓鞘动物模型中髓鞘修复的作用。方法:持续给予CPZ喂养12周诱导小鼠慢性脱髓鞘模型,采用快蓝染色、髓鞘碱性蛋白(MBP)免疫组织化学显色等方法检测各组髓鞘变化,观察典型性抗精神病药氟哌啶醇和非典型性抗精神病药喹硫平对髓鞘修复的作用。通过免疫组织化学标记少突胶质前体细胞(OPCs)标志物Olig2,比较药物对OPCs的影响。结果:氟哌啶醇可以阻止髓鞘的自发性修复;喹硫平能促进慢性髓鞘再生的进程。在髓鞘修复过程中氟哌啶醇使OPCs数目减少;喹硫平可以促进OPCs增生。结论:在脱髓鞘模型中,氟哌啶醇抑制髓鞘自发修复,喹硫平可以促进髓鞘的慢性修复,其机制可能与两种药物对OPCs的不同作用有关。OPCs可能是抗精神病药治疗的靶点。     

Mdivi-1对cuprizone诱导的脱髓鞘性病变小鼠少突胶质细胞的保护作用

目的:探讨线粒体分裂抑制剂1(Mdivi-1)对cuprizone诱导的脱髓鞘性病变模型小鼠少突胶质细胞损伤的作用及其机制。方法:将8周龄雄性C57BL/6小鼠用含0. 2%cuprizone的饲料饲喂,制备脱髓鞘性病变模型。将小鼠随机分为DMSO正常组(腹腔注射DMSO+饲喂正常饲料)、cuprizone模型组(饲喂含cuprizone的饲料)、DMSO+cuprizone模型组(腹腔注射DMSO+饲喂含cuprizone的饲料)和Mdivi-1干预组(腹腔注射Mdivi-1+饲喂含cuprizone的饲料)。通过固蓝染色及PLP、p-Drp1(Ser616)、CFB、C1q、C3b和C5b-9的免疫荧光染色实验检测Mdivi-1对髓鞘和少突胶质细胞的保护作用。结果:饲喂含cuprizone的饲料42 d可成功诱导小鼠脱髓鞘性病变模型,导致大脑胼胝体区髓鞘丢失,诱导Drp1磷酸化水平升高及C1q和CFB补体途径激活,并导致攻膜复合体在少突胶质细胞上组装。给予Mdivi-1可明显减少髓鞘丢失,抑制补体激活和攻膜复合体在少突胶质细胞的组装。结论:Mdivi-1干预可缓解cuprizone诱导的小鼠脱髓鞘病理学改变,其机制可能与抑制补体激活替代途径有关。     

Cuprizone诱导髓鞘损伤再生模型中Sip1的表达变化及其意义

目的:研究Smad相互作用蛋白1(Sip1)在cuprizone诱导髓鞘损伤再生模型中的表达变化及其意义。方法:通过在饲料中掺入cuprizone喂食C57BL/6小鼠建立髓鞘损伤模型,利用黑金(black gold,BG)染色方法及Western Blot方法,检测髓鞘损伤模型是否建立成功;利用Western Blot方法检测在髓鞘损伤及再生过程中Sip1的表达情况。结果:BG染色方法检测到喂药6周后模型组小鼠与对照组相比,着色显著降低,Western Blot方法检测到模型组小鼠MOG(myelin oligodendrocyte glycoprotein)蛋白表达水平显著降低,GFAP(glial fibrillary acidic protein)蛋白表达水平显著增高,证明髓鞘损伤模型建立成功。在模型建立成功后,停止喂药,改用正常饲料喂养4周后,通过Western Blot检测到模型组小鼠MOG蛋白水平显著恢复,证明该阶段髓鞘已再生。利用Western Blot方法检测髓鞘损伤模型建立阶段及髓鞘再生阶段的Sip1蛋白水平,结果显示与对照组小鼠相比,在髓鞘损伤阶段,模型组小鼠的Sip1蛋白水平显著增加,在髓鞘再生阶段Sip1蛋白水平同样显著增加。结论:Sip1在髓鞘损伤再生过程中具有重要作用,本研究为Sip1作为治疗髓鞘相关疾病的靶点提供了理论依据。     

星形胶质细胞在cuprizone介导的急性脱髓动物模型中的变化及其意义

目的:利用cuprizone制备髓鞘可再生的急性脱髓鞘动物模型,探讨脱髓鞘疾病髓鞘再生机制。方法:在饲料中掺入cuprizone饲育小鼠,通过调控饲育时间,造成神经脱髓鞘及髓鞘再生,并利用免疫荧光染色和原位杂交方法,检测不同时间点髓鞘的脱失和再生情况以及星形胶质细胞的反应。结果:cuprizone饲育6周后,动物小脑和胼胝体白质内髓鞘脱失严重,星形胶质细胞增殖活跃;在恢复正常饲料后,髓鞘基本恢复正常结构,星形胶质细胞仍处于活化增殖状态。结论:利用cuprizone可制备髓鞘可再生的急性脱髓鞘动物模型,星形胶质细胞的活化增殖对髓鞘再生具有重要作用。     

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.