Ferritin immunohistochemistry as a marker for microglia

Summary An immunohistochemical analysis of formalin-fixed, paraffin-embedded brain sections was performed with antisera against holoferritin and the light(L)-subunit of ferritin. Sections immunostained using anti-glial fibrillary acidic protein (GFAP), Ricinus communis agglutinin-1 (RCA-1) stain for microglia and iron stain (Berlin blue stain) were compared. The L-subunit of ferritin was purified from normal human spleen according to the modified scrapie-associated fibrils purification, and the antiserum was raised in a rabbit. Both ferritin antisera positively stained resting and, more markedly, reactive microglia, both of which were also stained with RCA-1 but not with GFAP. Ferritin-positive resting microglia were seen more abundantly in cerebral and cerebellar cortices than in white matter. The advantages of ferritin antisera over RCA-1 are as follows. (1) RCA-1 heavily stains blood vessels, while anti-ferritin does not, hence the microglial cells are more readily visualized with ferritin immunohistochemistry. (2) Reactive microglia and macrophages are more strongly stained with anti-ferritin. (3) The staining intensity of ferritin is independent of the length of tissue fixation in formalin. However, anti-ferritin is inferior to RCA-1 in staining resting microglia with a scanty cytoplasm, especially in the white matter, probably because the former recognizes cytoplasmic components, while the latter recognizes cell membrane. Iron stain only gave a reaction to microglial cells in brains with neurosyphilis and to hemosiderin-laden macrophages. Thus, in addition to RCA-1, ferritin antisera are useful as a microglia marker in formalin-fixed, paraffin-embedded sections.Supported in part by Dr. A. Kondo, Department of Neuropathology, Neurological Institute, Kyushu University     

Twisted plywood architecture of collagen fibrils in human compact bone osteons

Summary Ultrathin sections of decalcified human compact bone, observed by transmission electron microscopy, reveal that collagen fibrils can be distributed in the form of a superimposed series of nested arcs. This characteristic pattern has never been interpreted in previous works on compact bone structure. We demonstrate, by goniometric observations at the ultrastructural level, that such series of nested arcs are a consequence of the “twisted plywood” architecture of collagen fibrils in the compact bone matrix. In the same specimens, an “orthogonal plywood” disposition of collagen fibrils is also observed; a transition exists between these two types of orders. We show that the “twisted plywood structure” accounts well for certain optical properties of osteons, observed in polarizing microscopy, described as “intermediate osteons.” The particular geometry of collagen fibrils, leading to nested arcs in oblique sections, is analogous to the distribution of molecules in certain liquid crystals (called cholesteric liquid crystals). The principle of a liquid crystalline self-assembly of the collagen matrix in bone is therefore discussed.     

BRI基因在一对转移能力不同的肺腺癌细胞系中的序列分析与表达研究

目的 确认淀粉样纤维蛋白基因(amyloid fibrils，BRI)基因在l对同源但转移能力不同的肺腺癌细胞系AGZY83-a和Anip973中的序列并分析其表达。方法 采用测序技术，Northern印迹杂交。G显带后荧光原位杂交分析BRI基因在肺腺癌细胞系的序列与表达。结果 BRI基因在高转移肺腺癌细胞系Anip973中高表达，在其低转移母系AGZY83-a中低表达，两细胞系BRI基因染色体定位区均存在断裂重排。该基因染色体定位区在Anip973中出现扩增。已知BRI基因的-116bp～-5bp处碱基序列和-115bp～-5bp处碱基序列在AGZY83-a和Anip973中分别突变为CTCAGCAGCCCGC和TCAGCCGC。结论 BRI基因在转移能力不同的肺腺癌细胞系差异表达与该基因的染色体定位区域的断裂重排无关，与该基因染色体定位区拷贝数增加及5′非翻译区存在不同的突变可能相关。     

Scanning electron microscopic studies of reticular framework in the rat mesenteric lymph node

Background: The reticular framework in the lymph node has in the past been studied mainly by light microscopy of silver-impregnated specimens. The aim of the present study is to understand three-dimensionally the ultrastructure and organization of the reticular framework better than before. Methods: The mesenteric lymph nodes of the rat were prepared either an alkali-water maceration method or a conventional method and were observed in a scanning electron microscope (SEM). Results: The SEM study of alkali-water macerated tissues visualized directly the reticular fiber network in the lymph node. The reticular fibers consisted of thin bundles of collagem fibrils. They were continuous with the collagen fibriliar sheaths of blood vessels and lymphatic sinuses as well as with the fibrous capusule, thus acting as a skeleton of the lymph node. The arrangement of the reticulum was variable, depending on individual compartments. The SEM study of conventionally treated tissues, on the other hand, clarified the shape of reticular cells and their relationship with the reticular fibers. The sinus reticular cells connected with the sinus lining cells but separated from the parenchymal reticular cells, indicating that the former two originate from lymphatic endothelial cells. The parenchymal reticular cells varied in shape depending on their locations but essentially shared features with fibroblasts. Conclusions: The arrangements of the reticular fibers in the parenchyma were closely related to the associated reticular cells, showing the possibility that the reticular cells maintain the shape of the reticular framework suitable for each compartment of the lymph node. © 1995 Wiley-Liss, Inc.     

大鼠肝内移植肿瘤与肥大细胞关系的形态学研究

目的：研究大鼠肝内移植肿瘤与其周边肥大细胞的关系。方法：建立40只雄性Wistar大鼠肝内移植肿瘤模型，运用HE染色，肥大细胞（mast cell，MC）Alcian blue特殊染色，苦味酸-天狼猩红染色和电镜等技术，观察移植肿瘤肝组织的形态学改变，肿瘤周边浸润MC的数量以及MC与肿瘤组织的关系，8只正常大鼠为对照组。结果：肿瘤组织周边部分肝细胞形态学异常；肝组织内胶原纤维增生，主要为Ⅰ型和Ⅲ型胶原，并包绕肿瘤组织，肿瘤周边MC浸润，并沿胶原纤维分布，不同大鼠其肿瘤周边MC数量不一，有的差异明显。超微结构观察显示MC通过多个接触点与肿瘤细胞紧密相连，并释放胞质颗粒内容物，导致肿瘤细胞崩解。结论：MC与肿瘤组织有着非常密切的关系，MC可能通过多种途径直接和间接地发挥抗肿瘤作用。     

Ultrastructural Features of Epidermolysis Bullosa

Epidermolysis bullosa (EB), a heterogeneous group of hereditary diseases, varies in mode of inheritance, extent, severity, and presence or absence of scarring and dystrophy. Fourteen cases (13 in infants and 1 in a young adult) were studied. Subtyping by ultrastructural findings in normal and blistered skin biopsies was as follows: EB simplex (2), EB letalis (3), EBD dominant (2), and EBD recessive (7). One case diagnosed as recessive dystrophic by electron microscopy (EM) followed a benign course with little scaring and was re-classified clinically and after reviewing the EM as dominant dystrophic. Defining the level of bulla formation by EM allowed accurate diagnosis of subtypes. In 6 patients with EBD recessive, normal and bullous skin showed collagenolysis and no anchoring fibrils. In patients with EBD dominant, rudimentary fibrils were noted in normal skin. Whether absence of anchoring fibrils is primary or secondary in these two types and the role of collagenolysis remain unresolved.     

Amyloid fibrils induce dysfunction of hippocampal glutamatergic silent synapses

Silent glutamatergic synapses lacking functional AMPA (α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazoleproprionate) receptors exist in several brain regions including the hippocampus. Their involvement in the dysfunction of hippocampal glutamatergic transmission in the setting of Alzheimer's disease (AD) is unknown. This study demonstrated a decrease in the percentage of silent synapses in rats microinjected with amyloid fibrils (Aβ_1–40) into the hippocampal CA1. Also, pairing low‐frequency electric stimuli failed to induce activation of the hippocampal silent synapses in the modeled rats. Immunoblotting studies revealed a decreased expression of GluR1 subunits in the hippocampal CA1 synaptosomal preparation, indicating a potential reduction in the GluR1 subunits anchoring in postsynaptic density in the modeled rats. We also noted a decreased expression of phosphorylated cofilin, which regulates the function of actin cytoskeleton and receptor trafficking, and reduced expression of the scaffolding protein PSD95 in the hippocampal CA1 synaptosome in rats injected with Aβ_1–40. Taken together, this study illustrates dysfunction of hippocampal silent synapse in the rodent model of AD, which might result from the impairments of actin cytoskeleton and postsynaptic scaffolding proteins induced by amyloid fibrils.