We describe a new formulation for a hydrophilic resin, mostly composed of glycol methacrylate and hydroxypropyl methacrylate and here referred to as bioacryl, that allows the performance of morphological and immunohistochemical investigations at both light and electron microscopic levels. Immunolocalizations performed on bioacryl-embedded tissues are characterized by high specificity with virtually absent background staining. Finally, the new resin yields satisfactory fine-structural preservation, resulting in ultrastructural images of better quality than those obtained with Lowicryl K4M.

CD99 is a unique 32-kDa cell surface molecule with broad cellular expression but still poorly understood biological functions. In cancer cells, CD99 is highly expressed in virtually all Ewing's sarcoma (ES). Engagement of CD99 induces fast homotypic aggregation of ES cells and caspaseindependent apoptosis. In this study, we analysed signal transduction after CD99 engagement on ES cells. Findings obtained with selective inhibitors indicated that only actin cytoskeleton integrity was essential for cell-cell adhesion and apoptosis of ES cells. Indeed, CD99 stimulation induced actin repolymerization, further supporting the role of cytoskeleton in CD99 signaling. Gene expression profiling of ES cells after CD99 engagement showed modulation in the expression of 32 genes. Among the pool of upregulated genes reported to be involved in cell adhesion, we chose to analyse the role of zyxin, a cytoplasmic adherens junction protein found to play a role in the regulation of the actin cytoskeleton. Overexpression of zyxin after CD99 ligation was confirmed by real-time PCR and Western blot. Treatment of ES cells with zyxin antisense oligonucleotides inhibited CD99-induced cell aggregation and apoptosis, suggesting a functional role for this protein. Therefore, our findings indicate that CD99 functions occur through reorganization of cytoskeleton and identify actin and zyxin as the early signaling events driven by CD99 engagement.

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A copolymer of L-lactic acid and epsilon-caprolactone (PLLACL) was synthesized with the aim of preparing a bioartificial, small-diameter and partially resorbable vascular graft. The material was submitted to surface functionalizations (i.e. chemical modification by means of hydrolytic 'etching' and plasma discharge) to promote endothelial cell (EC) adhesion and growth avoiding platelet adhesion or coagulation factor absorption. Furthermore, the behaviour of human microvascular endothelial cells (HMVEC) seeded on the untreated and treated copolymer is described, as well as the platelet adhesion and the modifications of coagulation factors determined by the copolymer itself. PLLACL in its native state provided little support for EC adhesion. Improved EC adherence was obtained when functional groups were provided on the polymer surface by surface chemical hydrolysis. HMVEC seeded and cultured on the polymer surface did not show any ultrastructural alteration, thus demonstrating the absence of the polymer cytotoxicity. Moreover, SEM analysis performed on cold plasma modified specimens showed the presence of a subconfluent monolayer of EC, with an elongated spread morphology. Both the untreated and treated copolymers induced only slight variations of platelet number, but determined the activated partial thromboplastin time (APTT) increase, due to factor XI reduction. Finally, a prototype of partially biodegradable vascular prosthesis was prepared with NaOH/HCl-treated copolymer. Pre-cultured HMVEC seeding of the prosthesis by means of a rotation device resulted in an almost completely coverage of the graft inner surface.

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Filamentous inclusions (FI) are unusual, irregularly shaped cytoplasmic inclusions, which are mostly found in acinar cell carcinomas of the pancreas and are consequently thought to be an abnormal zymogen granule type. This study describes identical inclusions in acinar, centroacinar, and small duct epithelial cells from nonneoplastic pancreas, as well as those found in tumor cells from a mixed acinar-endocrine pancreatic carcinoma. An ultrastructural and immunogold labeling demonstration indicates that these inclusions are aggregates of intermediate filaments immunoreacting with the anti-cytokeratin AE1/AE3 mixture and with V9 clone anti-vimentin monoclonal antibodies. Their pleomorphic appearance, variable immunoreactivity, and frequent association with lipid droplets and secondary lysosomes, mostly of the angulate type, led to the hypothesis that the FI undergo a degenerative remodeling pathway similar to that proposed for hepatic Mallory bodies. A survey of the literature on FI and human tumors suggests that they are a variably expressed ultrastructural feature of tumor cells originating from exocrine cell-containing tissues, namely the pancreas and gastrointestinal tract.

A composite carcinoma of the gastric body consisting of endocrine and mucous epithelial cells with interspersed amphicrine cells is reported together with ultrastructural and immunocytochemical documentation of endocrine and nonendocrine differentiation. The tumor was associated with hypergastrinemia related to chronic atrophic gastritis (achlorhydria) and with multiple proliferative lesions, such as intramucosal microcarcinoid (IMC) and endocrine cell proliferations of the micronodular and linear type, which are currently regarded as carcinoid precursor changes. Ultrastructurally, a composite architecture with amphicrine features was demonstrated in the primary tumor, IMC, and liver metastases. On the other hand, the endocrine cell proliferations exclusively contained gastrin and enterochromaffinlike cells. Immunostaining with antibodies to calcitonin documented a number of positive cells both in the primary and in the metastatic sites. This is the first report of mixed exocrine-endocrine-amphicrine components both in a metastasizing carcinoma and in its precursor lesions in a chronic hypergastrinemic state. Unlike previously reported lesions, the endocrine component was unexpectedly composed of calcitonin cells, which are not usually present in the gastric mucosa.