CD59特异位点的短肽封条对HeLa细胞凋亡作用的研究

目的:研究CD59特异位点的短肽封条对HeLa细胞凋亡相关基因(survivin、caspase-3及bax)的表达作用,探讨CD59特异位点的短肽封条促HeLa细胞凋亡的作用机制.方法:将CD59特异位点的短肽封条分别作用于HeLa细胞和转CD59基因的HeLa细胞.作用24 h后,采用MTT的方法来检测细胞增殖抑制率;并利用免疫组织化学方法检测survivin,caspase-3及其bax的表达水平.结果:转CD59基因的HeLa细胞 短肽的细胞组增殖抑制率大于HeLa细胞 短肽组(P＜0.01).转CD59基因的HeLa细胞 短肽组和正常的HeLa细胞 短肽组相比较,survivin表达水平降低(P＜0.05);而caspase-3表达水平增高(P＜0.05);bax的表达量各组比较,差别无统计学意义.结论:CD59特异位点的短肽封条具有下调survivin的表达,活化caspase-3,从而促进HeLa细胞的凋亡.     

RNA干扰对宫颈癌细胞中E6AP基因的影响及其意义

目的 探讨RNA干扰(RNAi)对宫颈癌细胞系HeLa细胞E6AP基因表达及细胞增殖和凋亡的影响.方法 实验分为3组:空白对照组(未经转染的HeLa细胞)、转染阴性对照的小干扰RNA(siRNA)组及转染特异性E6AP siRNA组.采用半定量RT-PCR技术、Western blot方法 检测E6AP mRNA、蛋白表达水平,用四甲基偶氮唑蓝比色(MTT)法检测细胞增殖状况,用流式细胞术检测细胞凋亡.结果 转染E6AP siRNA 24、48、72 h后,E6AP siRNA组E6AP mRNA表达水平与对照siRNA组比较下降33%、72%、70%.Western blot结果 显示,在转染48及72 h,E6AP蛋白表达下降38%、59%.MTT法检测显示,转染HeLa细胞24、48、72、96 h后细胞生长速度明显降低,E6AP siRNA组与空白对照组(F=101.38,P＜0.05)、对照siRNA组(F=38.64,P＜0.05)比较,差异均有统计学意义.E6AP siRNA作用24、48、72 h后E6AP siRNA组凋亡率明显高于对照siRNA组(F=41.48,P＜0.05)和空白对照组(F=86.36,P＜0.05),差异有统计学意义.结论 体外合成的siRNA能有效封闭宫颈癌细胞中E6AP基因的表达,抑制细胞增殖,促进细胞的凋亡,为宫颈癌的基因治疗提供理论依据.     

Survivin反义寡核苷酸对骨肉瘤细胞凋亡的诱导效应

目的：利用骨肉瘤OS-732细胞，探讨survivin反义寡核苷酸（ASODN）对survivin基因表达的影响及其诱导肿瘤细胞凋亡的效应。 方法: 设计合成特异性靶向survivin的ASODN，以不同浓度和时间对OS-732细胞进行转染，并设空白、正义（SODN）对照组进行比较。采用RT-PCR、Western blotting、免疫细胞化学技术检测各组OS-732细胞中survivin mRNA、蛋白表达状态，吖啶橙/溴化乙锭（AO/EB）染色法、流式细胞仪检测细胞凋亡水平和形态变化，MTT法检测细胞生长抑制情况，激酶活性测定法检测细胞中caspase-3活性程度。 结果: 转染ASODN各组OS-732细胞survivin mRNA和蛋白表达均明显弱于空白对照组、SODN组；细胞凋亡率（AI）显著增加，细胞生长相应受抑，caspase-3活性显著提高；上述效应在ASODN各组存在一定的时间浓度依赖性；而SODN各组与空白对照组间各项指标均无明显差异。 结论: ASODN能够特异性下调OS-732细胞中survivin基因表达，激活凋亡效应蛋白酶caspase-3，在诱导肿瘤细胞凋亡、抑制增殖中发挥重要作用。     

靶向TRIM29基因的siRNA通过抑制PI3K/AKT信号通路诱导鼻咽癌细胞凋亡

目的:探讨沉默TRIM29基因表达对鼻咽癌细胞凋亡及PI3K/AKT信号通路的影响。方法:将人鼻咽癌5-8F细胞分为空白组、阴性对照(NC)组(转染阴性对照siRNA)和si-TRIM29组(转染TRIM29的特异性siRNA),通过CCK-8法检测si-TRIM29转染5-8F细胞0～96 h的细胞活力。通过流式细胞术及Western blot分别检测si-TRIM29转染5-8F细胞48 h的细胞凋亡率及TRIM29、cleaved caspase-3、cleaved caspase-9、Bcl-2、Bax、t-AKT和p-AKT的蛋白水平。10μmol/L的PI3K/AKT信号通路特异性抑制剂LY294002及si-TRIM29单独或联用处理细胞,细胞分为空白组、LY294002组和LY294002+si-TRIM29组,流式细胞术检测3组细胞凋亡率。结果:转染TRIM29 siRNA的5-8F细胞TRIM29蛋白表达明显低于空白组(P0.05)。和空白组比较,si-TRIM29组细胞活力明显降低,凋亡率明显升高,cleaved caspase-3、cleaved caspase-9和Bax蛋白的水平明显升高,Bcl-2和p-AKT蛋白的水平明显降低(P0.05)。LY294002组的细胞凋亡率高于空白组,而LY294002+si-TRIM29组的细胞凋亡率高于LY294002组(P0.05)。结论:沉默TRIM29基因表达可通过抑制PI3K/AKT信号通路诱导鼻咽癌细胞凋亡。     

DEK表达下调通过抑制胃癌SGC-7901细胞中NF-κB信号途径诱导细胞凋亡

目的:研究DEK表达下调对胃癌SGC-7901细胞凋亡的影响,并分析其与NF-κB信号途径及凋亡相关蛋白表达的关系。方法:将DEK siRNA和对照siRNA转染胃癌SGC-7901细胞,并将SGC-7901细胞分为未处理组、对照siRNA组及DEK siRNA组。采用实时荧光定量PCR和Western blot检测3组胃癌SGC-7901细胞中DEK mRNA和蛋白的表达;流式细胞术检测3组SGC-7901细胞凋亡的变化;Caspase-Glo-3/9试剂盒检测3组SGC-7901细胞中caspase-3和caspase-9的活性;Western blot技术检测3组SGC-7901细胞中NF-κB信号途径关键调控蛋白p65及凋亡相关蛋白Bcl-2和Bax的表达。结果:与未处理组和对照siRNA组相比,DEK siRNA组SGC-7901细胞中DEK的mRNA和蛋白表达水平显著下调(P0.05)。DEK siRNA组SGC-7901细胞的早期凋亡率和总凋亡率均显著高于未处理组和对照siRNA组(P0.05)。最为显著的是,DEK siRNA转染细胞后,p65和Bcl-2蛋白表达下调,Bax蛋白表达上调,并伴随caspase-3和caspase-9活性上升。结论:DEK表达下调介导的SGC-7901细胞凋亡可能与NF-κB信号途径密切相关。     

Hax-1 siRNA对黑素瘤A375细胞化疗敏感性的影响

目的:探讨Hax-1 siRNA对黑素瘤A375细胞化疗敏感性的影响.方法:MTT法、 AnnexinV-FITC/PI染色、 Hoechst 33258染色、 Western blot检测Hax-1 siRNA联合顺铂或苦参碱对细胞增殖、凋亡和caspase-3活性形式表达的影响.结果:相同药物浓度作用下, Hax-1 siRNA转染组细胞抑制率、凋亡率及cleaved caspase-3表达明显高于未转染组和转染无关载体组(P＜ 0.05);荧光显微镜下观察, 相同药物浓度作用下, Hax-1 siRNA转染组细胞凋亡现象较明显.结论:Hax-1 siRNA增强顺铂或苦参碱对黑素瘤A375细胞的增殖抑制和诱导凋亡作用, 该作用可能和caspase-3的活性形式表达增强相关.     

Survivin特异性siRNA诱导胰腺癌细胞凋亡的研究

目的 观察survivin特异性siRNA对胰腺癌细胞株Panc-1细胞增殖和凋亡的影响.方法 体外构建Survivin特异性siRNA表达载体p-Survivin-siRNA,转染胰腺癌细胞株Panc-1细胞系,RT-PCR和Western印迹法检验其对胰腺癌细胞株Panc-1细胞的RNA干扰(RNAi)效果.采用MTT法分析其对细胞增殖的影响,流式细胞仪检测其对细胞周期的影响.同时,采用Western印迹法检测半胱氨蛋白酶 3(caspase 3)的表达变化.结果 p-survivin-siRNA表达质粒高效而特异地剔降胰腺癌细胞株Panc-1细胞中survivin的表达,抑制肿瘤细胞增殖(P<0.01),阻断胰腺癌细胞株Panc-1细胞在G1期.随着survivin基因被沉默,caspase 3表达升高(P<0.01).结论 靶向survivin基因的siRNA表达载体可以显著抑制胰腺癌细胞株Panc-1细胞增殖,促进细胞凋亡.     

miR-155特异性siRNA增强阿糖胞苷诱导的Burkitt淋巴瘤Raji细胞凋亡

 目的：研究miR-155特异性siRNA增强阿糖胞苷（Ara-C）诱导的Burkitt淋巴瘤Raji细胞凋亡及其机制。方法：Ara-C与miR-155 siRNA单独或者联合干预Raji细胞增殖。qRT- PCR检测脂质体转染siRNA后miR-155的表达;CCK-8法检测细胞增殖;流式细胞术检测细胞凋亡;Western blotting法检测caspase-3的表达。结果：qRT-PCR显示,转染miR-155 siRNA后,Raji细胞的miR-155表达明显下降（P<0.05）,Ara-C或miR-155 siRNA单独处理细胞后均显示出增殖抑制作用,而两者联合使用的增殖抑制作用更显著（P<0.05）。各组细胞进行药物干预48 h后行流式细胞术,结果显示Ara-C或miR-155 siRNA单独处理细胞凋亡率分别为（16.5±0.3）%和（14.6±0.3）%,与对照组［（3.6±0.4）%］比较差别有统计学意义（P＜0.05),Ara-C+miR-155 siRNA组的凋亡率［（38.4±1.4）%］分别与Ara-C和miR-155 siRNA单独处理组比较,差别有统计学意义（P＜0.05）。Ara-C+miR-155 siRNA组与Ara-C组及miR-155 siRNA组相比,caspase-3的水平明显增高。结论：miR-155特异性siRNA具有增强阿糖胞苷对Raji细胞增殖抑制及诱导Raji细胞凋亡的作用,其机制与caspase-3凋亡途径有关。     

TPX2对人肺癌细胞增殖、凋亡及cleavedcaspase-3表达的影响

目的 探讨Xklp2靶蛋白(TPX2)对人肺癌细胞增殖、凋亡及活化的半胱氨酸天冬氨酸蛋白酶3(cleaved caspase-3)表达影响。方法 培养人肺癌细胞A549,分为Control组(不进行细胞转染)、siRNA-NC组(细胞转染TPX2 siRNA control)、TPX2 siRNA组(细胞转染TPX2 siRNA),采用实时荧光定量PCR (qPCR)和Western blot检测TPX2 siRNA的转染效果。取转染后各组细胞,采用噻唑蓝检测细胞增殖情况,流式细胞术检测细胞凋亡情况,Western blot检测cleaved caspase-3蛋白表达情况。结果 TPX2 siRNA组中,TPX2 mRNA、蛋白水平和细胞光密度(OD)值均明显低于Control组和siRNA-NC组,细胞凋亡率、细胞中cleaved caspase-3蛋白表达水平均明显高于Control组和siRNA-NC组,差异均有统计学意义(P值均<0.05);而siRNA-NC组中,TPX2 mRNA、蛋白水平及细胞OD值、细胞凋亡率、细胞中cleaved caspase-3与Control组比较,差异均无统计学意义(P值均＞0.05)。结论TPX2 siRNA能够干扰人肺癌细胞A549中TPX2的表达。下调TPX2的表达能够抑制人肺癌细胞A549增殖,促进caspase-3活化,促进人肺癌细胞A549的凋亡。     

特异性siRNA体外抑制HDGF基因对人大肠癌细胞凋亡的影响

目的：了解HDGF基因在体外是否对大肠癌细胞凋亡具有调控作用。方法设计特异性小干扰RNA抑制HDGF基因表达,本试验分为3组：空白对照组、非特异性siRNA转染的阴性对照组及HDGF特异性siRNA干扰组。通过AnnexinV?FITC流式双染, Hoechst 33258荧光染色等方法检测转染前后细胞凋亡变化,运用免疫印迹法检测转染HDGF?siRNA前后相关凋亡蛋白的变化情况。结果与2个对照组相比, HDGF?siRNA处理组细胞早期凋亡率明显上升至（14．1±1．24）％,差异具有统计学意义（P＜0．05）,在形态学上有20％的细胞出现染色质浓染的凋亡小体,而对照组基本未见;此外与2个对照组相比, HDGF?siRNA处理组细胞中bcl?2及Survivin蛋白含量均有明显下调,而Bax明显上调、 Cyt?c从线粒体释放到胞浆、 caspase?9及caspase?3被激活。结论 HDGF?siRNA能在体外有效诱导大肠癌胞发生凋亡,线粒体凋亡途径在HDGF基因介导的凋亡调控中起重要作用,这暗示HDGF将可能成为大肠癌基因治疗的一个极佳的分子靶点。     

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.