Resilience to structural and molecular changes in excitatory synapses in the hippocampus contributes to cognitive function recovery in Tg2576 mice

Plaques of amyloid-β(Aβ)and neurofibrillary tangles are the main pathological characteristics of Alzheimer’s disease(AD).However,some older adult people with AD pathological hallmarks can retain cognitive function.Unraveling the factors that lead to this cognitive resilience to AD offers promising prospects for identifying new therapeutic targets.Our hypothesis focuses on the contribution of resilience to changes in excitatory synapses at the structural and molecular levels,which may underlie healthy cognitive performance in aged AD animals.Utilizing the Morris Water Maze test,we selected resilient(asymptomatic)and cognitively impaired aged Tg2576 mice.While the enzyme-linked immunosorbent assay showed similar levels of Aβ42 in both experimental groups,western blot analysis revealed differences in tau pathology in the pre-synaptic supernatant fraction.To further investigate the density of synapses in the hippocampus of 16-18 month-old Tg2576 mice,we employed stereological and electron microscopic methods.Our findings indicated a decrease in the density of excitatory synapses in the stratum radiatum of the hippocampal CA1 in cognitively impaired Tg2576 mice compared with age-matched resilient Tg2576 and non-transgenic controls.Intriguingly,through quantitative immunoelectron microscopy in the hippocampus of impaired and resilient Tg2576 transgenic AD mice,we uncovered differences in the subcellular localization of glutamate receptors.Specifically,the density of GluA1,GluA2/3,and mGlu5 in spines and dendritic shafts of CA1 pyramidal cells in impaired Tg2576 mice was significantly reduced compared with age-matched resilient Tg2576 and non-transgenic controls.Notably,the density of GluA2/3 in resilient Tg2576 mice was significantly increased in spines but not in dendritic shafts compared with impaired Tg2576 and non-transgenic mice.These subcellular findings strongly support the hypothesis that dendritic spine plasticity and synaptic machinery in the hippocampus play crucial roles in the mechanisms of cognitive resilience in Tg2576 mice.

Microstructure and mechanical properties of new Mg-Zn-Y-Zr alloys with high castability and ignition resistance

Complex studies of new Mg-Zn-Y-Zr system alloys have been carried out.The content range for the formation of the two-phase structure MgSS(Mg solid solution)+LPSO(long-period stacking ordered)in alloys of the Mg-Zn-Y-Zr system was determined by thermodynamic calculations.The effect of heat treatment regimes on microstructure,mechanical,and corrosion properties was invest-igated.The fluidity,hot tearing tendency,and ignition temperature of the alloys were determined.The best combination of castability,mechanical,and corrosion properties was found for the Mg-2.4Zn-4Y-0.8Zr alloy.The alloys studied are superior to their industrial counterparts in terms of technological properties,while maintain high corrosion and mechanical properties.The increased level of pro-perties is achieved by a suitable heat treatment regime that provides a complete transformation of the 18R to 14H modification of the LPSO phase.

Ultrastructural and Immunoelectron Microscopical Study of Human Pituitary Somatotroph Adenomas and Prolactinomas

Nowdays the application of immunohistochemical techniques and ultrastructuralanalysis and correlation with clinical and biochemical findings have led to a moredetailed functional classification,in which growth hormone (GH)-producing andprolactin (PRL)-producing adenomas have been shown to comprise more than halfof pituitary adenomaso.Few immunoelectron microscopic studies on GH and PRLadenomas have been made,however,in limited cases so far,though a numberof authors have described the characteristics of pituitary adenomas by conventionalelectron microscopy.In addition to routine electron microscopy,immuno-.electron microscopical technique using protein A-gold probes was applied in

A Statistical Evaluation of Uncoupling Protein 1 in the Limited Area of Brown Adipose Tissue by Immunoelectron Microscopy

Uncoupling protein 1 (UCP1) expressed by the brown adipose tissue (BAT) in the mitochondrial crista acts as a homeostatic thermogenerator of eutherians. The evaluation of UCP1 expression in the BAT offers significant scientific insight, especially in studies targeting limited areas such as the periarterial and pericardial regions of small experimental mammals. However, the negligible amount of this adipose tissue would render the general quantitative evaluation of the protein unreliable because of lipid contamination and low protein concentration. To address this problem, we quantitatively evaluated UCP1 expression in the mitochondrion of the mouse interscapular BAT using immunoelectron microscopy and immunohistochemical studies using a combination of primary and secondary antibodies in scheme A (rabbit anti-UCP1 IgG/gold particle-conjugated goat anti-rabbit IgG), B (rabbit IgG/gold particle-conjugated goat anti-rabbit IgG), C (rabbit anti-UCP1 IgG/gold particle-unconjugated goat anti-rabbit IgG), and D (rabbit IgG/gold particle-unconjugated goat anti-rabbit IgG). Scheme A shows the immunopositive reaction of obvious gold particles in the mitochondrial area, whereas other procedures revealed less distinctive reactions. The distinctive gold particle immunoreaction comprised electrical high-density spots with a mean diameter of >5 nm. However, in scheme B, the electrical high-density spots were scattered outside the mitochondrion and were significantly smaller than 4 nm;schemes C and D demonstrated few immunoreactions. Logistic regression analysis between schemes A and B showed that the threshold diameter of the electrical high-density spots measuring >5 nm indicated a true positive immunoreaction to anti-UCP1 antibody specifically in the mitochondrial area. Minor statistical difference was observed in the primary anti-UCP1 antibody between polyclonal IgG and monoclonal antibodies. Therefore, immunoelectron microscopy might be useful for evaluating negligible protein expression in some limited areas, such as UCP1 expression in the BAT of small experimental animals.

IMMUNOELECTRON MICROSCOPIC STUDY ON THE LOCALIZATION OF MONOCLONAL ANTIBODIES ON GASTRIC CANCER CELLS

The localization of three monoclonal antibodies (MAb) against gastric cancer was studied on two human gastric cancer cell lines by immunoelectron microscopic technique. It has shown that the corresponding antigens of MAb 3G9 and 3H11 were distributed on the microvilli (M) and non-microvillus (NM) plasma membrane of target cells, with various M to NM ratios depending on the MAbs and target cells used. However, the corresponding antigens of MAb PD4 was only localized on the surface of round or finger-like bulges of target cells and never on the microvilli and non-microvillous plasma membrane. Since the nature and function of these tumor antigens have not been identified yet, the implication of the different distributions of these antigens remians to be clarifated.

淀粉样管型肾病的临床病理特征分析

目的探讨轻链淀粉样管型肾病(light chain amyloid casts,LCAC)的临床病理学特征,加深对LCAC的认识。方法回顾2018年1月至2021年6月在广州金域医学检验中心肾脏病理诊断为LCAC的患者,将患者分为单纯LCAC(pure light chain amyloid casts,I-LCAC)组和LCAC合并轻链淀粉样变性肾病(light chain amyloid casts with light chain amyloid nephropathy,LCAC&AL)组,所有患者均进行了光镜、免疫荧光、电镜和免疫电镜检查,对两组患者的肾脏病理进行半定量评分进行分析,评估两组患者的临床病理学特征。结果同期诊断为轻链管型肾病(light chain cast nephropathy,LCCN)的患者共131例,其中15例诊断为LCAC(11.5%),包括ILCAC组10例和LCAC&AL组5例;LCAC有9例临床确诊为多发性骨髓瘤,其中I-LCAC组7例,LCAC&AL组2例,两组差异无统计学意义;与LCAC&AL组相比,I-LCAC组患者血肌酐水平[(766.1±472.5)μmol/L比(82.8±22.5)μmol/L]和发生贫血的比例(100%比40%)更高(P<0.05);ILCAC组患者的肾组织内每平方毫米的平均淀粉管型数[(7.3±5.0)个/mm²比(0.3±0.1)个/mm²]显著多于LCAC&AL组(P<0.05),管型的轻链类型以λ型多见;每平方毫米的平均淀粉管型数与患者的血肌酐水平呈正相关(R2=0.593)。结论LCAC的病因以多发性骨髓瘤最常见,管型多呈同心圆和分层状,中心区域染色较浅,而边缘嗜银呈“睫毛状”的病理形态特征和刚果红染色阳性,偏振光镜下有黄绿色双折光的染色特性,I-LCAC病理类型患者较LCAC&AL组更容易肾功能损伤,每平方毫米的平均淀粉管型数越多肾功能越差。

Possible Relevance of the Allende Meteorite Conditions in Prebiotic Chemistry: An Insight into the Chondrules and Organic Compounds

The study of the mineral and organic content of the Allende meteorite is important for our understanding of the molecular evolution of the universe as well as the ancient Earth. Previous studies have characterized the magnetic minerals present in ordinary and carbonaceous chondrites, providing information on the evolution of magnetic fields. The interaction of organic compounds with magnetic minerals is a possible source of chemical diversity, which is crucial for molecular evolution. Carbon compounds in meteorites are of great scientific interest for a variety of reasons, such as their relevance to the origins of chirality in living organisms. This study presents the characterization of organic and mineral compounds in the Allende meteorite. The structural and physicochemical characterization of the Allende meteorite was accomplished through light microscopy, powder X-ray diffraction with complementary Rietveld refinement, Raman and infrared spectroscopy, mass spectrometry, scanning electron microscopy, and atomic force microscopy using magnetic signal methods to determine the complex structure and the interaction of organic compounds with magnetic Ni-Fe minerals. The presence of Liesegang-like patterns of chondrules in fragments of the Allende structure may also be relevant to understanding how the meteorite was formed. Other observations include the presence of magnetic materials and nanorod-like solids with relatively similar sizes as well as the heterogeneous distribution of carbon in chondrules. Signals observed in the Raman and infrared spectra resemble organic compounds such as carbon nanotubes and peptide-like molecules that have been previously reported in other meteorites, making the Mexican Allende meteorite a feasible sample for the study of the early Earth and exoplanetary bodies.

慢性癫痫模型动物海马内GABA能神经元的超微结构改变

用马桑内酯诱发小鼠慢性癫痫模型，借助免疫电镜方法对海马的ＧＡＢＡ能神经元的超微结构进行观察，可见小鼠海马内ＧＡＢＡ免疫反应阳性神经元弥散分布于除锥体细胞层和颗粒细胞层外的各部。慢性癫痫小鼠海马内的ＧＡＢＡ免疫反应阳性神经元胞体和末梢均呈现程度不同的结构损伤，包括线粒体肿胀、细胞器崩解和神经末梢变性。ＧＡＢＡ样轴突末梢可与免疫反应阴性的树突构成传出性轴－树突触，也可接受免疫反应阴性轴突末梢的传入性轴－轴突触。在模型动物海马内的非ＧＡＢＡ能神经元结构与正常对照动物者相似，但线粒体有增多趋势，甚至成团聚集于神经末梢，未见结构损伤。此外，在癫痫小鼠，ＧＡＢＡ免疫反应产物还分布于星形胶质细胞和毛细血管内皮细胞胞浆内。以上实验结果表明：在慢性癫痫时ＧＡＢＡ在海马的含量减少，而非ＧＡＢＡ能神经元的代谢和活性增强，这些变化可能与癫痫的发病机理有关。

肾活检标本包埋后免疫电镜技术

目的 :探讨肾活检标本树脂包埋及低温包埋的免疫电镜技术。方法 :选择 9例膜性肾病和 7例IgA肾病的肾活检标本 ,分别进行IgG及IgA的免疫电镜标记 ,观察不同的固定方法及环氧树脂、低温包埋剂包埋后的免疫标记结果。结果 :低温包埋剂LRWhiteresin和LowicrylK4M包埋后的标本 ,IgG和IgA的标记密度均较高 ,两种包埋剂的标记效果相同 ;但LRWhiteresin对超微结构的保存优于LowicrylK4M。常规固定方法、Epon812包埋的标本 ,IgG及IgA均不能标出 ;混合固定液 (多聚甲醛加戊二醛 )固定、Epon812包埋的标本 ,IgG及IgA均可标出 ,但与低温包埋剂相比 ,标记密度较低。结论 :低温包埋剂LRWhiteresin和LowicrylK4M对免疫标记效果好 ,但较昂贵 ,难应用于临床。树脂包埋剂虽然免疫标记效果略差 ,但可作为一种诊断免疫电镜方法。

脑缺血时大鼠海马及其生长抑素神经元的超微结构改变

夹闭大鼠双侧颈总动脉２ｈ后，对海马ＣＡ１区进行免疫电镜观察。可见实验组ＣＡ１区部分锥体细胞的胞核固缩、核染色质溶解、细胞器减少或消失；部分神经纤维的髓鞘显示轻度变性图像；部分神经末梢变性；星形胶质细胞突起肿胀；小胶质细胞活跃并包裹断离的髓鞘；生长抑素免疫反应阳性神经末梢比对照组显著增多，生长抑素阳性轴突可与阴性树突形成轴一树突触。以上结果提示：缺血可导致海马ＣＡ１区神经元发生不同程度的损伤和胶质细胞反应，继而引起生长抑素神经元的反馈性兴奋，释放生长抑素增多，刺激存活的锥体细胞，使之兴奋，从而参与脑缺血的发病过程。

猪流行性腹泻与猪传染性胃肠炎病毒的电镜和免疫电镜观察

应用电镜（ＥＭ）和免疫电镜（ＩＥＨ）技术对猪流行性腹泻病毒（ＰＥＤＶ）和胃肠炎病毒（ＴＧＥＶ）进行了观察。ＥＭ结果表明两者在形态上存在有细微差异：ＰＥＤＶ为多形性，粒子大小变化范围较大，纤突短小而密集，核芯呈多形性；ＴＧＥＶ为圆形，或椭圆形，粒子大小较均一，纤突大而稀疏，核芯为环形。ＩＥＭ结果ＰＥＤＶ与ＴＧＥＶ无免疫交叉反应。可应用ＥＭ和ＩＥＭ对ＰＥＤＶ和ＴＧＥＶ做实验室诊断。

脾原发性非何杰金淋巴瘤

以光镜、电镜、胶体金探针免疫电镜、组化和免疫组化等方法，观察１６例脾原发性非何杰金淋巴瘤（ＮＨＬ），发现其镜下分布有三种基本类型，即结节型、弥漫型和过渡型。发现属低度恶性的不同组织学类型ＮＨＬ在红髓和白髓有特殊的浸润方式：结节型小裂细胞性，其结节分布于整个脾脏的红髓，大小及分布较一致，未见侵犯红髓，但有独特的侵犯中央动豚周围Ｔ细胞淋巴鞘的形态，且可能与淋巴细胞循环和“归家”机制有关；过渡型小无裂细胞性，主要呈结节状，但红髓可见小片弥漫的瘤细胞浸润，并与结节有移行改变；过渡型Ｂ混合细胞性，结节较少，部分红髓破坏，代之以弥漫分布的瘤细胞。而弥漫型则主要见于恶性程度较高的组织细胞性和大裂细胞性等。此外，还讨论了脾原发性ＮＨＬ的鉴别诊断、诊断标准、大体分型和临床特点等问题。

药流绒毛中波形蛋白的免疫荧光和免疫电镜研究

目的 :观察米非司酮对人孕早期绒毛组织中波形蛋白 (Vimentin)表达的影响。方法 :应用间接免疫荧光和胶体金标记免疫电镜技术 ,检测正常早孕人流电吸组和米非司酮组绒毛组织中波形蛋白的表达。结果 :对照组绒毛中轴间质细胞、血管内皮细胞波形蛋白阳性表达 ,药流组荧光着色细胞则明显减少 ,表达强度显著降低 ;对照组绒毛间质细胞波形蛋白中间丝沿细胞的长轴呈良好的丝状排列 ,整齐、致密 ,胶体金颗粒成簇或散在分布于细胞核与细胞质之间除细胞器以外的细胞质所有部位 ,胞核呈阴性 ;药流组间质细胞中间丝明显辣少 ,出现断裂、排列紊乱 ,金颗粒分布明显稀疏。结论 :米非司酮显著降低绒毛中波形蛋白表达水平并影响绒毛间质细胞的细胞骨架成分。

大鼠海马内谷氨酸神经元与GABA神经元之间突触联系的免疫电镜双标研究

为了探讨神经递质在癫痫发病机理中的作用，用包埋前免疫电镜双标法研究了正常大鼠海马ＣＡ_１，区谷氨酸（Ｇｌｕ）神经元与ＧＡＢＡ神经元之间的突触联系。先用ＤＡＢ为呈色剂显示ＧＡＢＡ免疫反应，然后以钼酸铵－ＴＭＢ法显示Ｇｌｕ免疫反应，再进行免疫电镜包埋。观察发现：在海马ＣＡ_１区锥体细胞层有许多Ｇｌｕ免疫反应阳性神经元；在锥体细胞层、多形层和辐状层可见一些ＧＡＢＡ免疫反应阳性神经元，胞体为锥体或多角形。在多形层还可见ＧＡＢＡ阳性树突与Ｇｌｕ阳性轴突形成对称性树－轴突触，在辐状层可见ＧＡＢＡ阳性轴突与Ｇｌｕ阳性树突形成对称性轴－树突触。此外，在多形层和辐状层内尚可见到Ｇｌｕ阳性轴突与Ｇｌｕ阳性树突之间形成对称性轴－树型自调节突触，ＧＡＢＡ阳性轴突之间形成对称性和非对称性轴－轴型自调节突触。上述结果首次证实在海马ＣＡ_１区兴奋性Ｇｌｕ神经元与抑制性ＧＡＢＡ神经元之间存在着复杂的突触联系，从而为不同神经递质参与癫痫发病机理提供了超微结构依据。

肝细胞肝癌中卵圆细胞的组织学与超微结构研究

目的 :探讨人肝癌肝组织存在卵圆细胞的可能性。方法 :对 2 0例人肝细胞肝癌的手术标本行常规组织学和超微结构观察 ,并用胆管上皮分化标记CK7和肝细胞分化标记白蛋白对以上组织作免疫组化染色 ,同时对其中 5例作免疫电镜标记。结果 :光镜下 ,14/ 2 0例癌肿边缘常可见到增生的小胆管样结构。电镜下 ,14/ 2 0例可找到三型卵圆细胞。其中Ⅰ型细胞体积较小、核大、胞质少 ,此为较为原始的卵圆细胞。Ⅱ型细胞体积稍大 ,胞质稍多 ,此为向胆管上皮分化的小上皮细胞。Ⅲ型细胞体积稍大 ,内含稍多粗面内质网 ,此为向肝细胞分化的卵圆细胞。此三型卵圆细胞均有细胞内张力微丝和细胞间连接结构。免疫电镜显示 ,三型卵圆细胞均表达CK7和白蛋白 ,但Ⅰ型和Ⅱ型表达CK7多些 ,Ⅲ型表达白蛋白多些。结论 :与动物致癌模型肝中存在卵圆细胞一样 ,人肝细胞肝癌肝中也存在同样形态和免疫表型特点的卵圆细胞。结果支持卵圆细胞可能为肝前体细胞的假设。

K562细胞分泌的exosome的免疫电镜研究

目的:通过免疫电镜方法观察K562细胞分泌的 exosome,探讨其潜在的临床应用价值.方法:采用离心超滤和 蔗糖密度梯度离心等方法分离出K562细胞释放的exosome, 经透射电镜观察其超微结构.采用固相免疫电镜法(SPIEM) 制备exosome的HSP70,ICAM 1及ABL免疫电镜标本.结果: K562细胞分泌的exosome为直径50～100nm的膜性微囊结 构,圆形或椭圆形,腔内为低电子密度成分.经抗HSP70, ICAM 1和ABL抗体 胶体金免疫电镜标记,囊外膜及腔内可 见点状、颗粒状电子致密物沉积.结论:离心超滤和蔗糖密度 梯度离心法纯化小量exosome方法可行,K562细胞分泌的ex osome表达HSP70,ICAM 1和ABL蛋白,具备免疫原性.

垂体催乳素细胞腺瘤的电镜及免疫电镜观察

应用胶体金免疫电镜及常规电镜技术,对垂体催乳素(PRL)细胞腺瘤42例进行了观察。观察结果,3例为多颗粒型,39例为少颗粒型,其中4例还含有生长激素(GH)颗粒。PRL瘤细胞中分泌颗粒电子密度高,均匀,形状及大小不一。少颗粒型PRL瘤中多见异位外排现象,部分PRL瘤细胞中还能查见纤维小体。

肾轻链沉积病和轻链型淀粉样变的电镜及免疫电镜研究

目的 :探讨电镜及免疫电镜方法在肾轻链沉积病 (lightchaindepositiondisease,LCDD)和轻链型淀粉样变(amyloid ,AL)诊断中的作用。方法 :对我院 1 994年 1月至 2 0 0 2年 2月间的肾活检病例进行电镜观察 ,对疑为LCDD及早期AL的病例进行轻链 (κ、λ)的免疫电镜标记。结果 :6例符合LCDD的诊断 ,36例符合AL的诊断。LCDD电镜下可见肾小管基底膜外侧、肾小球基底膜内侧、鲍曼囊外侧及小血管壁的点状、颗粒状电子致密物质沉积 ,其中 2例早期病例表现颗粒状物质节段性分布 ;免疫电镜标记 ,颗粒状物质被单种轻链标记 ,其中κ轻链 4例 ,λ轻链 2例。AL电镜下可见肾小球系膜区、毛细血管壁及小动脉壁的纤维物质分布 ,其中 1 5例早期病例表现系膜区或 /及毛细血管壁的纤维结构呈节段性分布 ;1 5例早期AL的免疫电镜标记结果 ,纤维结构被单种轻链标记 ,其中κ轻链 4例 ,λ轻链 1 1例。结论 :肾脏LCDD及早期AL的诊断需依赖于电镜检查 。

盖玻片在培养细胞免疫电子显微术中的应用(英文)

体外培养的细胞不仅可用于研究其形态和机能的变化,而且可进行不同药物学作用时细胞内抗原成分的定位检测及细胞特征的研究。通常盖玻片放入培养皿中作为培养细胞的支持物,细胞在盖玻片上长成单层,可立即固定、染色,进行光学显微镜的观察。在实验中我们发现,加盖玻片的单层细胞培养法也可以直接应用于免疫电镜的包埋前和包埋后染色方法。该技术具有以下优点。(1)使用盖玻片可以避免免疫电镜标本制作过程中,为了搜集细胞而进行的数次刮取、离心。免疫反应及后固定、脱水、浸透、包埋均在盖玻片上进行,使培养细胞的损伤降低至最小程度。(2)如果在直径3.5cm的培养皿中进行免疫过氧化物酶反应大约需要至少200μl抗体,而使用盖玻片法,每张盖玻片则仅需要10μl抗体,大大节约了免疫反应的抗体量,既简便又经济。(3)盖玻片法使包埋后培养细胞呈单层位于包埋块的表面,在每一张超薄切片中都能观察到很多细胞。

IL-1的Ⅰ型受体在大鼠颈动脉体中的超微定位

目的 研究IL 1的Ⅰ型受体 (IL 1RⅠ )在大鼠颈动脉体内的表达和亚细胞定位。 方法 灌流固定的正常大鼠颈动脉体组织 ,用冰冻置换法包埋 ,超薄切片 ,胶体金免疫组织化学染色 ,电镜下观察。 结果 IL 1RⅠ样免疫反应阳性产物主要存在于主细胞 ,胶体金颗粒分布在胞膜、胞浆和胞浆中的细胞器及细胞核。支持细胞和毛细血管内皮细胞的胞浆中也可见少量免疫胶体金颗粒。 结论 IL 1RⅠ在大鼠颈动脉体特别是主细胞中有较强表达 ,此结果为进一步研究颈动脉体作为细胞因子化学感受器的可能性提供形态学基础。