The ultrastructure of transmissible murine colonic hyperplasia.

Transmissible murine colonic hyperplasia was examined ultrastructurally by sequential sampling after inoculation with the etiologic agent, Citobacter freundii. Light-microscopic changes in the descending colon of inoculated mice were correlated with scanning and transmission electron-microsopic findings. Bacteria were attached to the surface of the mucosa between 4 and 10 days after inoculation. Hyperplasia was most severe at 16 days and thereafter underwent regression. Regression was preceded by extrusion of infected cells from the surface mucosa and replacement by immature hyperplasia epithelium. Hyperplastic epithelium throughtout the crypt resembled undifferentiated crypt cells of controls. By 45 days, the mucosa had reverted to near normal structure. The results suggest that severe mucosal proliferation with minimal inflammatory change resulted from attachment of bacteria to the surface mucosal epithelium. The hyperplastic response appeared to be a defense mechanism of replacing infected cells with newly migrated, uninfected epithelium.     

应激性溃疡胃壁胆碱能神经超微结构变化

目的：探讨脑血管病发生时应激性溃疡的发病机理及防治。方法：采用透射电镜和组化电镜技术，观察了１０例应激性胃溃疡病人及４例正常人胃壁的胆碱能神经的超微结构，用多功能医学图像分析系统检测了神经终末的囊泡数目和大小，进行统计学处理。结果：组化电镜下乙酰胆碱酯酶（ＡＣｈＥ）阳性反应物以散在颗粒形式出现在神经纤维内，其大小不等，直径约６０ｎｍ。神经终末有３种囊泡：无颗粒、有颗粒和大暗颗粒囊泡。检测无颗粒囊泡数目，病人的（９９％）高于正常人的（７６％），Ｐ＜０．０１。结论：应激性溃疡发病与胆碱能神经密切相关     

The ultrastructure of the clamp wall of the monogenean gill parasiteGastrocotyle trachuri

Summary The clamp wall ofGastrocotyle trachuri has been found to consist predominantly of radially orientated myofibres. Nearly all the myofibres appear to be almost completely filled with myofilaments; these being of two kinds, thick and thin ones arranged in a manner similar to that observed in other platyhelminth muscles. Nothing resembling dense bodies was observed within the fibres, but at both ends of the fibres electron dense attachment plaques are present. These attachment plaques appear to have a dual function acting both as hemidesmosomes and as attachment points for the thin filaments. The detailed structure of the fibres suggests that the clamp wall is in fact composed of single radially orientated sarcomeres.The possible role of the clamp wall in the attachment of the parasite to its host is briefly discussed.     

Aneurysmal bone cyst,a study of ultrastructure and malignant transformation

Summary Four cases of aneurysmal bone cyst, of which one became malignant 7 years after irradiation, were studied by electron microscopy. The aneurysmal bone cyst was composed of four different types of stromal cells — fibroblasts, myofibroblasts, osteoblasts, and histiocytes — and osteo-clastlike multinucleated giant cells. The surface of blood spaces was devoid of specialized endothelium, which may explain the presence of large quantities of extravasated erythrocytes. Some histiocytes contained siderosomes. The malignant lesion consisted of two main types of stromal cells, of which one had electron lucent and the other electron dense cytoplasm. The stromal cells produced osteoid and the tumour was regarded as an osteosarcoma. The multinucleated giant cells resembled those observed in aneurysmal bone cysts, but the nuclei seemed to be more often spherical. It is concluded that irradiation of the aneurysmal bone cyst may cause sarcomatous transformation in a cell capable of producing osteoid.     

Cutaneous bronchogenic cyst of the abdominal wall

We report a case of the unusual location of a cutaneous bronchogenic cyst on the abdominal wall. The patient was a 9-month-old boy who had presented with a 1.5 cm-sized polypoid mass, present since birth. Pathological examination of the excised mass revealed multiple small cystic structures surrounded by the fibroadipose tissue. The lining epithelium consisted of either pseudostratified ciliated columnar epithelium with goblet cells or a single layer of ciliated or non-ciliated cuboidal to columnar cells. The cystic walls contained a well-developed smooth muscle bundle, mucous glands and hyaline cartilage plate. This lesion was adherent to the peritoneum, but there was no direct communication with the abdominal cavity. Cutaneous bronchogenic cyst located in the abdominal wall has not been described in the English literature. The present case suggests a possible origin from a downward migration, from the sequestered bud of a tracheobronchial tree primordium along the midline of the body surface, during embryonic development.     

胃壁支气管源性囊肿一例

患者男,62岁。因CT发现胃壁包块3年多于2004年6月1日入院。3年多前患者常规体检时CT示胃小弯后方、脾脏右侧软组织块影,直径约4cm,性质待定。因患者自觉良好,无恶心、呕吐、腹痛和腹泻等症状,故未及时就医。患者2个月前因特发性血小板减少性紫癜入院治疗,2周后缓解出院。体检:无阳性发现。血常规:红细胞4.53×1012/L,血红蛋白109g/L,血小板104×109/L;血清甲胎蛋白(AFP)、癌胚抗原(CEA)、CA199和CA125水平均在正常范围内。B超示:左上腹脾脏前方内侧可见大小约5.2cm×3.5cm的无回声团。CT示:胃后方、脾内侧及胰尾部前上方见直径约7.5…     

The cyst wall carbohydrate composition of Balamuthia mandrillaris

Balamuthia mandrillaris is an opportunistic cyst-producing amoeba that can cause rare, but fatal, Balamuthia amoebic encephalitis (BAE). Cysts are resistant to harsh environmental conditions and many antimicrobial compounds and thus can contribute to BAE recurrence. However, little is known of cyst wall synthesis, cyst wall composition, or how encystment is induced. In this study, we examined the carbohydrate composition of the cyst wall. The major components were mannose (20.9 mol%) and glucose (79.1 mol%), with trace amounts of galactose present in the cyst wall samples analysed. The linkage analysis showed cyst wall carbohydrates with apparently linear and branching saccharides and suggested the presence of cellulose. These components may play an important protective role by creating a permeability barrier around the cyst.     

Carcinoid tumor arising in the wall of a congenital bile duct cyst.

We report an extremely rare case of carcinoid tumor arising in a congenital choledochal cyst. The dilated choledochal cyst in a 66-year-old Japanese woman was surgically resected, after which the ovoid elevated tumor, measuring 1.5 x 1.5 cm, was detected in the proximal portion of the cyst. A carcinoid tumor was histologically confirmed. To the best of our knowledge, this is the first published case of carcinoid tumor in a choledochal cyst.     

Isolation and characterization of a cDNA clone encoding a thiol proteinase of Sarcocystis muris cyst mero` zoites (Apicomplexa)

A cDNA library of Sarcocystis muris cyst merozoites was screened using a digoxigenin-labeled probe. This probe was derived from a 504-bp polymerase-chain-reaction fragment representing part of a thiol proteinase. Several cDNA clones were isolated, one of which (PH08) consists of a nucleotide sequence of 1694 bp and encodes the complete prepropolypeptide of a cathepsin L-like proteinase. PH08 contains an open reading frame of 394 amino acid (aa) residues with a 46-residue signal sequence, which is followed by a 129-residue propeptide and 219 aa residues of the mature enzyme. Two potential glycosylation sites and a putative polyadenylation signal were also identified. The occurrence of the highly conserved interspersed ERFNIN aa motif, not found in cathepsin B-like proteinases, suggests the classification of the enzyme as a cathepsin L-like proteinase. Results worked out in this study will enable production of the recombinant thiol proteinase of S. muris cyst merozoites necessary for study of the substrate specificity as well as other biochemical parameters of this enzyme. Received: 20 January 1999 / Accepted: 3 February 1999     

Calcifying odontogenic cyst immunohistochemical detection of keratin and involucrin in cyst wall

Summary Calcifying odontogenic cysts (COC) were immunohistochemically described using different keratin proteins and involucrin as well as histopathology. The cystic lining epithelium was composed of calcifying, keratinizing, squamous, and columnar epithelial cells, and included calcified masses of irregular shape and various size as well as ghost cells. Calcifying epithelium gave negative or only trace staining for keratins detected with low molecular keratin (PKK1), but were regularly positive with high molecular keratin (KL1) and polyclonal antibody for keratin (TK). They were occasionally positive for involucrin. The cells located in the periphery of the calcified masses had a particular abundance of high molecular weight and total keratins (KL1 and TK). Calcified bodies and ghost cells were devoid of any immunoreactivity. Squamous epithelium was relatively similar to that of normal squamous cell epithelium in the oral mucosa. It were most commonly found in columnar cystic epithelial cells which displayed intense staining with all immunoreagents. It is postulated that such epithelial cells may have a strong potentiality to transform into ghost cells or to undergo metaplasia. They may develop altered synthesis of homogenous acellular materials and finally become transformed into calcifying epithelium containing dystrophic calcified masses.     

Foregut cyst of the oesophageal wall in a cynomolgus monkey (Macaca fascicularis)

Congenital oesophageal cysts of foregut origin are rare in animals and human beings. This report describes a case in a 4-year-old cynomolgus monkey with no clinical symptoms. The cyst, which was located within the oesophageal submucosal tissue near the mid-point of the oesophagus, was lined with pseudostratified ciliated epithelium and had a thin layer of submucosal tissue. The cyst was surrounded by a smooth muscle layer which was partly intermingled with the circular muscle layer of the oesophagus. The muscularis mucosae of the oesophagus was not shared with the cyst wall. Simple tubular glands were present, opening into the cyst lumen. No communication between the cyst lumen and the oesophagus was observed. Cartilaginous tissue, which is a diagnostic feature of bronchogenic cysts, was not identified in the cyst wall. On the basis of the histopathological features, a foregut cyst of the oesophagus was diagnosed.     

The cyst wall of Entamoeba invadens contains chitosan (deacetylated chitin)

The cyst wall of Entamoeba invadens (Ei), a model for the human pathogen Entamoeba histolytica, contains chitin, which is a homopolymer of beta-1, 4-linked N-acetyl-glucosamine (GlcNAc). In fungi and in bacteria that make nodulation factors, chitin deacetylases make chitosan, which is a mixture of GlcNAc and glucosamine and so has a positive charge. The activity of an Ei chitin deacetylase was revealed by a 3-4-fold increase in released GlcNAc when deproteinated cyst walls were chemically acetylated prior to treatment with a commerical chitinase. Because this chitinase releases GlcNAc but not GlcN, increases in released GlcNAc after acetylation suggested the presence of chitosan in Ei cyst walls. Five putative Ei and Eh chitin deacetylase genes resembled those of fungi and bacteria. A predicted Eh chitin deacetylase matched closely the three-dimensional structure of a Bacillus subtilis peptiodglycan deacetylase. A recombinant Eh chitin deacetylase, expressed in Saccharomyces cerevisiae, deacetylated chitooligosaccharides in vitro. These results are consistent with the idea that Ei chitin deacetylases modify chitin to produce chitosan in the Ei cyst wall.     

Initial characterization of CST1, a Toxoplasma gondii cyst wall glycoprotein

Toxoplasma gondii is an important protozoan pathogen of humans that can cause encephalitis in immunocompromised individuals such as those with AIDS. This encephalitis is due to reactivation of latent infection in T. gondii-seropositive patients. Latent organisms survive within tissue cysts, which are specialized parasitophorous vacuoles containing bradyzoites. The cyst wall of this structure is produced by modification of the parasitophorous vacuole by the parasite and is important in cyst survival. The components of the cyst wall have been poorly characterized. By using immunofluorescence and immunoelectron microscopy, we have identified a monoclonal antibody (MAb 93.18) that reacts with the cyst wall. This antibody recognizes a 116-kDa glycoprotein, which we have termed CST1, containing sugar residues that bind Dolichos biflorans lectin (DBA). CST1 is distinct from T. gondii antigen labeled with succinyl Triticum vulgare lectin (S-WGA) and represents the major DBA-binding component in T. gondii. The carbohydrate components of the tissue cyst, such as CST1, are probably important in both providing stability and facilitating persistence in its host. As is seen in the carbohydrate capsules of fungi, glycoproteins in the T. gondii cyst wall may protect cysts from the immune response of the host. Further characterization of the formation of the cyst wall and its components should lead to insights into the mechanism of tissue cyst persistence and may suggest novel therapeutic approaches to eliminate tissue cysts of this organism.     

Characterization of a SRS13: a new cyst wall mucin-like domain containing protein

Parasitology Research - Toxoplasma gondii, an obligate intracellular apicomplexan, causes latent infection in about one third of the human population. During latent infection, T. gondii bradyzoites...     

Amplification of genomic DNA fragments of Sarcocystis muris (Apicomplexa) cyst merozoites encoding a thiol (cysteine) proteinase

Parasites of the phylum Apicomplexa (Sporozoa) cause diseases such as malaria, toxoplasmosis, or intestinal coccidiosis. Invasive stages possess typical apical organelles such as dense granules that harbor a broad range of polypeptides that are believed to take part in the parasite-host cell interaction. In previous studies a 26-kDa polypeptide of dense granules from Sarcocystis muris cyst merozoites (bradyzoites) was characterized as a thiol (cysteine) proteinase. In this paper a method is demonstrated to amplify DNA fragments from genomic DNA of S. muris cyst merozoites by polymerase chain reaction, which probably code for the 26-kDa antigen. Received: 12 December 1997 / Accepted: 17 January 1998