The role of coronary arteriography in demonstration of mural thrombosis after angioplasty. Insights from an experimental model.

Although intracoronary thrombosis often occurs after angioplasty and may affect its outcome, the accuracy of arteriography for identification of mural thrombi is unclear. This study analyzed the relationship between arteriographic abnormalities immediately before death and the histologic extent of thrombosis in 77 dogs submitted to balloon injury of intact left anterior descending coronary arteries. Survival time after angioplasty was 120 min. The incidence of mural thrombosis, defined on serial histologic sections, was 65.0 percent. A positive diagnosis of intracoronary thrombus at arteriography (AT+) was based on the presence of any of the following signs: filling defects, retention of contrast material, and slowed or interrupted flow. Seventeen dogs were AT+, and 60 were AT-. The overall sensitivity of arteriography was 34 percent, and the specificity was 100 percent. Even considering as significant only thrombi greater than 25.0 percent of the arterial lumen area, 11 of 27 dogs were AT- despite thrombus sizes between 27 percent and 75 percent of lumen area (sensitivity, 59 percent); arteriography consistently missed smaller thrombi (22 of 23 dogs were AT-). Arterial diameters and balloon-induced injury were similar between AT- and AT+ dogs. Scanning electron microscopy depicted a fibrin-poor thrombus in 14 of 19 AT+ dogs and a fibrin-rich thrombus in five, whereas all seven AT+ dogs had fibrin-rich thrombi. Logistic regression analysis showed a correlation between thrombus size and arteriographic positivity, whereas the presence of fibrin and slowed flow of contrast material did not independently predict positive arteriographic results. Thus, arteriography is inaccurate for identification of mural thrombosis after angioplasty, mostly because of its poor sensitivity.

Effect of spatial arrangement of the basement membrane on cultured pleomorphic adenoma cells. Study by immunocytochemistry and electron and confocal microscopy.

In a cell line from human pleomorphic adenoma (AP2 cells) we studied the response of these cells to basement membrane proteins. The culture was characterized as myoepithelial-like by transmission electron microscopy and immunocytochemistry. AP2 cells were grown in contact with a reconstituted basement membrane (Matrigel). Cells grown on Matrigel showed conspicuous phenotypic alterations, depending on how the substrate was applied. Cells grown on the top of Matrigel developed a dendritic phenotype, exhibiting thin, long and intercommunicating cytoplasmic extensions resembling normal myoepithelial cells. Cells grown inside Matrigel formed multi-layered clusters. Light, confocal and transmission electron microscopy showed that these clusters were formed by double-layered epithelioid cells delimiting luminal spaces. The cells facing the lumen were cuboidal, showing microvilli at the apical plasmalemmal and junctional complexes. The spatial arrangement of basement membrane is a key modulator of morphogenetic changes and cytodifferentiation of tumour myoepithelial cell lineage in culture.

The effect of a reconstituted basement membrane (matrigel) on a human salivary gland myoepithelioma cell line.

We have already demonstrated that a reconstituted basement membrane (Matrigel) is a key modulator of morphogenetic changes and cytodifferentiation of pleomorphic adenoma cells in culture. Myoepithelioma is considered to be a neoplasm closely related to pleomorphic adenoma and should experience similar induction processes. Thus, the aim of this study was to investigate whether Matrigel would influence myoepithelioma cells. We used a cell line derived from a human salivary gland plasmacytoid myoepithelioma (M1 cells) grown in a three-dimensional preparation of Matrigel. Phenotype differences were assessed using conventional light microscopy technique (haematoxylin and eosin) and phase and differential interference contrast (Nomarski). Immunofluorescence was carried out to detect smooth-muscle actin, laminin and type-IV collagen. M1 cells exhibited all proteins studied, showing a myoepithelial differentiation. M1 cells grown inside Matrigel presented morphological changes and changes in smooth-muscle actin status. By growing M1 cells inside Matrigel, it was possible to reproduce the tumour architecture with no duct-like structures. Based on our findings, we suggest that myoepithelioma would be derived from a cell with a commitment to myoepithelial differentiation. We also suggest that the mechanical properties of the matrix environment will likely regulate smooth-muscle actin expression in myoepithelioma.

The effect of laminin and its peptide SIKVAV on a human salivary gland myoepithelioma cell line.

We have demonstrated that the basement membrane regulates the myoepithelioma. We are now studying the effect of laminin, a basement membrane protein, in the morphology of a cell line (M1) derived from human salivary gland plasmacytoid myoepithelioma. These cells were grown inside a three-dimensional preparation of laminin-1. Phenotype differences were assessed by light and transmission electron microscopy. In addition, we analysed the effect of a molecular domain of laminin-1, the peptide SIKVAV, on M1 cells. This peptide was chosen because it is effective in cell proliferation and differentiation. M1 cells grown inside laminin-1 were mostly plasmacytoid-like, while cells treated by SIKVAV showed light and electron microscopic features of typical plasmacytoid cells. This peptide also modulated smooth-muscle actin expression in M1 cells. We demonstrated that laminin-1 and its derived peptide SIKVAV morphoregulates myoepithelioma cells in culture.

Laminin-1 and SIKVAV a laminin-1-derived peptide, regulate the morphology and protease activity of a human salivary gland adenoid cystic carcinoma cell line.

In a previous paper, we demonstrated that laminin-1 and its derived peptide SIKVAV modulates the morphology of an adenoid cystic carcinoma cell line (CAC2 cells). Light microscopy of CAC2 cells grown in three-dimensional preparations of SIKVAV-enriched laminin-1 showed the presence of pseudocystic spaces. Pseudocysts are hallmarks of adenoid cystic carcinoma in vivo. We hypothesized that these pseudocystic spaces could be due to the protease-inducing/activating role of SIKVAV. Thus, we studied the presence of matrix metalloproteinases (MMPs) in CAC2 cells treated either by laminin-1 or by SIKVAV-enriched laminin-1. Immunohistochemistry and zymography suggested that SIKVAV enhanced the secretion of MMP-2 and MMP-9 in CAC2 cells. We propose that SIKVAV induces pseudocystic formation probably through the secretion of MMPs 2 and 9.

Morphometric study of nucleolar organiser regions in ameloblastoma and basal cell carcinoma.

Ameloblastoma and basal cell carcinoma share histological similarities. Morphometric analysis of nucleolar organiser regions (NORs) from ameloblastoma and basal cell carcinoma (BCC) was carried out by silver (Ag) staining. Mean counts were lower in ameloblastoma (1.652 +/- 0.032) compared to those in BCC (2.354 +/- 0.054). Ameloblastoma presented one or two NORs per nucleus, in a narrow distribution (one to four NORs per nucleus). In contrast, BCC exhibited two or three NORs per nucleus, in a broad distribution (one to six NORs per nucleus). Perimeter and area measurements of AgNOR dots yielded significantly higher mean values for ameloblastoma. Our data suggest that most BCC cells are in mitosis, showing small and numerous NORs in each nucleus, while ameloblastoma cells are in interphase, showing one or two large NORs in each nucleus. Although ameloblastoma and BCC are neoplasms with similar growth patterns, they have cell populations with statistically significant differences in AgNOR patterns.

Analysis of epithelial-myoepithelial carcinoma based on the establishment of a novel cell line.

Epithelial-myoepithelial carcinoma of the salivary gland is a rare, low-grade, neoplasm, composed of ductal and myoepithelial cells. We present two novel cell lines, which have been characterised by immunofluorescence, derived from an epithelial-myoepithelial carcinoma of the parotid gland. A resected mass of the parotid gland was diagnosed as an epithelial-myoepithelial carcinoma by routine histological examination. Part of the specimen was labelled with a panel of antibodies confirming the tumour type. The other part was finely minced and the explants were incubated in DMEM supplemented with penicillin and streptomycin, at 37 degrees C in a humidified 5% CO(2) atmosphere. Two cell types were identified by immunofluorescence-a small cobblestone cell, positive for AE1/AE3 and p53, and a polyhedral cell, positive for vimentin, smooth muscle markers and S-100. Herein two cell lines are presented in order to open up possibilities of new studies and a discussion of the events that culminate in this bimodal neoplasm is also performed.

Brefeldin-A induces apoptosis in human adenoid cystic carcinoma cultured cells.

Adenoid cystic carcinoma (ACC) of salivary glands is characterized by a high rate of local recurrences, neurotropism and metastasis. ACC long-term survival rate is not promising. Thus, different chemotherapeutical approaches had been proposed for this neoplasm, including apoptosis induction by different drugs. This work evaluates the efficacy of Brefeldin-A (BFA), a potent apoptosis inducer, on ACC cultured cells (CAC2 cell line). CAC2 cells were treated with a 375 microM BFA solution in serum-free medium during 18 h. CAC2 cells grown in DMEM supplemented with 10% fetal bovine serum served as controls. Apoptotic cell recognition and counting were carried out through Hoechst staining. Transmission electron microscopy and immunofluorescence assessed the effect of BFA on CAC2 cells phenotype. Treated cultures showed a high apoptotic index presenting +/-30% of cells in evident apoptosis, when compared to controls. Apoptotic CAC2 cells also exhibited different alterations such as cytoplasmic vesicles formation and mitochondrial changes. Cultured ACC cells are strongly susceptible to apoptosis induction under BFA treatment, which may constitute a promising tool in further chemotherapeutical approaches.

The role of basement membrane proteins on the expression of neural cell adhesion molecule (N-CAM) in an adenoid cystic carcinoma cell line.

We investigated the presence of neural cell adhesion molecule (N-CAM) in the adenoid cystic carcinoma cell line CAC2 using immunofluorescence microscopy. Additionally, we analysed the role of laminin and type IV collagen in N-CAM expression. We demonstrated that cultured adenoid cystic carcinoma cells express N-CAM. Control cells presented a scattered N-CAM expression on cell membrane, and type IV collagen had no effect in N-CAM distribution. CAC2 cells grown on laminin-coated coverslips expressed N-CAM concentrated on cell lamellipodia suggesting relationship with migratory activity. Our results showed that cultured adenoid cystic carcinoma cells express N-CAM and this expression is modulated by extracellular matrix.

Effect of N-CAM on in vitro invasion of human adenoid cystic carcinoma cells.

Adenoid cystic carcinoma of salivary glands is characterised by aggressive behaviour, high rate of local recurrences, neurotropism and late metastasis. In a previous work we demonstrated that adenoid cystic carcinoma cultured cells (CAC2 cells) expressed N-CAM. It was suggested that this expression, modulated by extracellular matrix, would be correlated to cell movement. The aim of our study was to verify whether CAC2 cells presented invasion capacity. Moreover, we tested whether the neural adhesion molecule (N-CAM) would participate in this process. CAC2 cells were either previously treated, or not (control), with a monoclonal antibody against N-CAM. Invasion assays were carried out using a modified Boyden chamber (Transwell chamber). CAC2 cells (10(5)) were dispensed into Transwell upper chamber on the top of Matrigel coated filter. The cells that invaded the filters in the first 8 h were counted under light microscopy, yielding data for the invasion rates (%). Control CAC2 cells presented an invasion rate of 5.28+/-0.04%. The invasion rate raised to 6.53+/-0.2% when N-CAM was blocked with monoclonal antibody. N-CAM impaired the adenoid cystic carcinoma cell invasion in vitro. Therefore, we suggest an anti-invasive role for N-CAM in adenoid cystic carcinoma.

Verruciform xanthoma of the oral mucosa. Report of four cases and a review of the literature.

We present four new cases of verruciform xanthoma (VX) in the oral mucosa and review the literature. Clinical, histological, and immunohistochemical features of four new cases of VX were analysed together with cases found in a review of the literature. Expression of CD-68 was studied by immunohistochemistry. Only 162 cases were reported in the oral mucosa. Ninety were males (55.5%) and 72 were females (44.5%). Mean age was 44.9 years. The majority of cases occurred in masticatory mucosa (69.7%). Our cases exhibited papillary or verrucous proliferation of squamous epithelium associated with hyperparakeratosis and with numerous foamy cells confined to the lamina propria papillae. Foamy cells were positive to CD-68 antibody, showing a macrophagic nature. VX is a rare benign lesion, and is probably inflammatory. However, its aetiology and pathological mechanisms remain unknown.

Moisture as a factor influencing the distributions of two species of terrestrial salamanders.

Plethodon richmondi shenandoah occurs in at least three geographically isolated talus slopes in Shenandoah National Park, Virginia, U.S.A., each surrounded by a continuous population of Plethodon c. cinereus in the soil outside the talus. Distributions are contiguous but largely non-overlapping. The talus presents a much drier habitat than does the surrounding soil. Four experiments were designed to test the responses of the two species to moisture and substrate. Although shenandoah lives in a habitat generally drier than that of cinereus, both species choose the wet end of a moisture gradient and do not differ significantly in moisture preference. When given choices between a substrate of rock or soil, the two species respond similarly: neither expresses a preference when both substrates are moist and both choose soil over rock as the substrates dry, showing that substrate preference is based on moisture content and not texture. A third experiment demonstrates that cinereus suffers significantly greater mortality and loss of body water when subjected to a drying rock substrate than when subjected to a soil substrate, since the latter holds moisture longer. Thus the talus most likely presents a greater stress of dehydration to salamanders than does the soil. A fourth experiment shows that when forced to dehydrate, shenandoah survives longer, loses significantly less body water per hour, and withstands a greater loss of body water before death than does cinereus.The conclusions drawn are that cinereus inhabits areas of deep soil not due to a preference for that substrate but due to the requirement of a moist substrate, and it cannot enter the talus due to the dry conditions there. P. r. shenandoah, on the other hand, neither prefers the rocky nor the dry conditions of the talus and is probably excluded from the soil by the presence of cinereus. The survival of shenandoah in the talus is due, at least in part, to its ability to withstand the stress of dehydration for a longer period than can cinereus.

Structural basis for mechanical transduction in the frog vestibular sensory apparatus: II. The role of microtubules in the organization of the cuticular plate.

The actin matrix of the cuticular plate, which supports the sensory stereocilia bundle, is coupled to the axial cytoskeleton of the hair cell through a well defined microtubule columnar framework. A collection of axial microtubules in a columnar organization penetrate deep into the dense actin matrix of the cuticular plate. Each microtubule displays at the end a 300-500 nm long fuzzy cap that enmeshes with the actin matrix of the cuticular plate. The microtubule associated proteins MAP-1A and MAP-1B were localized by confocal immunofluorescence to the point of microtubule insertion in the cuticular plate. These proteins are likely components of the microtubule capping structure and may mediate the interaction of the microtubules with the actin matrix. The structural interaction of the microtubules with the cuticular plate provides important mechanical coupling of the transduction apparatus to the axial cytoskeleton of the hair cell.

Effect of a ceramic and a non-ceramic hydroxyapatite on cell growth and procollagen synthesis of cultured human gingival fibroblasts.

BACKGROUND: Ceramic hydroxyapatites and non-ceramic hydroxyapatites have been used extensively as alloplastic materials for bone reconstruction. However, different forms of hydroxyapatite induce different types of tissue response. METHODS: Human gingival fibroblasts (FMM1 cells) were used to analyze ceramic and non-ceramic hydroxyapatite biocompatibility. The cells were grown on surfaces covered either by collagen (control group), collagen plus ceramic hydroxyapatite, or collagen plus non-ceramic hydroxyapatite. Scanning electron microscopy, growth and cell viability curves, and procollagen immunoprecipitation were obtained. For the growth and viability curves, 10(4) cells were seeded on 60 mm dishes. Cells from each group were counted, in triplicate, at 1, 3, 4, 5, and 6 days after seeding using the Trypan blue dye exclusion assay. RESULTS: The cells grew in close contact with both types of hydroxyapatite particles. No differences were found in the amount of procollagen synthesis among any experimental group. The cultures treated with ceramic hydroxyapatite had a growth delay for the first 5 days. There was no difference in cell viability between the control group and the non-ceramic hydroxyapatite group. However, cultures treated with ceramic hydroxyapatite showed significantly lower viability percentages than the other groups. CONCLUSIONS: Hydroxyapatite supports cell growth and fibroblast metabolism including collagen production, and hence is biocompatible. Cell viability and structural studies showed that non-ceramic hydroxyapatite has relevant physical and biological properties as an implant material.

An electron microscopic study of dental plaque of the rat incisor.

Because rat incisors continuously erupt they provide an opportunity for the study of dental plaque at all stages of its development. The youngest plaque would be visible at the gingival margin of the tooth as it erupts, and the older plaque higher on the tooth. The ultrastructural features of these plaques were studied by transmission electron microscopy. Cocci and short rods colonized the cementum surface, forming a monolayer. The plaque had a maximum thickness of about 40 microns, with the inner third rich in fibrillar matrix and the organisms forming microcolonies perpendicular to the tooth surface. Cells were haphazardly distributed in a loose matrix on the surface of the plaque. In the area of plaque disorganization the cementum was covered by isolated groups of bacteria and the matrix had holes in it. The rat mandibular incisor may provide a unique model for study of how plaque on cementum is initially formed, matures and finally is degraded.

White piedra: ultrastructure and a new micro-ecological aspect.

White piedra or trichosporosis is a superficial mycosis of the hair shaft, caused by the yeast Trichosporon beigelii; it has been found in all continents and may involve the hair of any part of the body. We report a case of white piedra on the hairs of the inguinal fold with ultrastructural studies. Transmission electron microscopy showed that the nodules have the same morphological aspects as the fungus in culture (hyphae and arthrospores) except for the presence of a cementant substance. By scanning electron microscopy the elimination of spores was seen on the nodule surface. Interestingly similar nodules were found on cotton fibres of the patient's underwear, which were also studied by scanning electron microscopy. This finding can explain therapeutic failure and demands special hygienic conditions related to clothes.

The effect of indirect trauma on the rat temporomandibular joint.

The effect of indirect trauma to the rat temporomandibular joint (TMJ) is analysed by means of an experimental model. The trauma, applied from an angle-glenoid fossa direction, produced injury of the TMJ. The histological data demonstrated that the impact could produce fractures of the glenoid fossa, but no hemarthrosis was observed. Trauma, both with or without fracture, caused proliferative changes in the TMJ. The glenoid fossa, the articular disk and the articular surface of the condyle were injured. Thickening of the articular surfaces had resulted in reduced joint space. Subsequently, remodelling changes in the condyle were found.

Expression of smooth-muscle actin in cultured cells from human plasmacytoid myoepithelioma.

OBJECTIVE: The definition of plasmacytoid myoepithelioma, a neoplasm exhibiting myoepithelial differentiation, has been recently questioned. To better understand the histogenesis of this neoplasm, we searched for myoepithelial markers in histologic sections of plasmacytoid myoepithelioma and in a cell line (M1) derived from this same neoplasm. STUDY DESIGN: Expression of vimentin, pan-keratin (AE-3) and smooth-muscle actin was studied by immunohistochemistry in paraffin-embedded tissue and by immunofluorescence in M1 cells. RESULTS: Plasmacytoid myoepithelioma tumor sections showed vimentin and AE-3 reactivity, but evidence of smooth-muscle actin was not seen. The cell line derived from this tumor also produced vimentin and cytokeratin. In addition, all cultured cells expressed smooth-muscle actin. CONCLUSION: We demonstrated that cells derived from a case of plasmacytoid myoepithelioma appear to show full myoepithelial differentiation in vitro. Thus, they are myoepithelial-like cells in nature. The lack of myogenous differentiation in vivo could be due to an inhibitory process mediated by the extracellular matrix.

Botryoid odontogenic cyst: report of a case with clinical and histogenetic considerations.

A case of a botryoid odontogenic cyst is reported. Some considerations regarding histogenetic and biologic behaviour of the lesion are discussed.

Myofibroma of gingiva: report of a case with immunohistochemical and ultrastructural study.

Oral myofibroma is an uncommon, benign, solitary proliferation of myofibroblastic tissue. Few cases affecting maxillofacial region have been reported. We present a case of gingival myofibroma, diagnosed on clinical, histopathological, immunohistochemical, and ultrastructural basis.