There is a great need for living valve replacements for patients of all ages. Such constructs could be built by tissue engineering, with perspective of the unique structure and biology of the aortic root. The aortic valve root is composed of several different tissues, and careful structural and functional consideration has to be given to each segment and component. Previous work has shown that immersion techniques are inadequate for wholeroot decellularization, with the aortic wall segment being particularly resistant to decellularization. The aim of this study was to develop a differential pressure gradient perfusion system capable of being rigorous enough to decellularize the aortic root wall while gentle enough to preserve the integrity of the cusps. Fresh porcine aortic roots have been subjected to various regimens of perfusion decellularization using detergents and enzymes and results compared to immersion decellularized roots. Success criteria for evaluation of each root segment (cusp, muscle, sinus, wall) for decellularization completeness, tissue integrity, and valve functionality were defined using complementary methods of cell analysis (histology with nuclear and matrix stains and DNA analysis), biomechanics (biaxial and bending tests), and physiologic heart valve bioreactor testing (with advanced image analysis of open-close cycles and geometric orifice area measurement). Fully acellular porcine roots treated with the optimized method exhibited preserved macroscopic structures and microscopic matrix components, which translated into conserved anisotropic mechanical properties, including bending and excellent valve functionality when tested in aortic flow and pressure conditions. This study highlighted the importance of (1) adapting decellularization methods to specific target tissues, (2) combining several methods of cell analysis compared to relying solely on histology, (3) developing relevant valve-specific mechanical tests, and (4) in vitro testing of valve functionality.
BackgroundThe immunohistochemical demonstration of Enhancer of zeste homologue 2 (EZH2) proved to be a useful marker in several tumor types. It has been described to distinguish reliably hepatocellular carcinomas from liver adenomas and other benign hepatocellular lesions. However, no other types of malignant liver tumors were studied so far.MethodsTo evaluate the diagnostic value of this protein in hepatic tumors we have investigated the presence of EZH2 by immunohistochemistry in hepatocellular carcinomas and other common hepatic tumors.EZH2 expression was examined in 44 hepatocellular carcinomas, 23 cholangiocarcinomas, 31 hepatoblastomas, 16 other childhood tumor types (rhabdomyosarcoma, neuroblastoma, Wilms’ tumor and rhabdoid tumor), 17 metastatic liver tumors 24 hepatocellular adenomas, 15 high grade dysplastic nodules, 3 biliary cystadenomas, 3 biliary hamartomas and 3 Caroli’s diseases.ResultsMost of the malignant liver tumors were positive for EZH2, but neither of the adenomas, cirrhotic/dysplastic nodules, reactive and hamartomatous biliary ductules stained positively.ConclusionsOur immunostainings confirm that EZH2 is a sensitive marker of hepatocellular carcinoma, but its specificity is very low, since almost all the investigated malignant liver tumors were positive regardless of their histogenesis. Based on these results EZH2 is a sensitive marker of malignancy in hepatic tumors. In routine surgical pathology EZH2 could be most helpful to diagnose cholangiocarcinomas, because as far as we know this is the first marker to distinguish transformed and reactive biliary structures. Although hepatoblastomas also express EZH2, the diagnostic significance of this observation seems to be quite limited whereas, the structurally similar, other blastic childhood tumors are also positive.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1173195902735693
It is thought that dysregulation of E-cadherin, syndecan-1 (CD138) and Ets-1 is involved in carcinoma development. E-cadherin is an important epithelial cell adhesion molecule; syndecan-1 (CD138) is a regulatory proteoglycan in both cell-cell and cell-matrix adhesion and Ets-1 is a proto-oncogene and transcription factor, which takes part in extracellular matrix remodeling. Our goal was to study the changes in the expression of these molecules during colon carcinoma development and progression. We tested 117 colon adenomas and 149 de novo and ex adenoma carcinomas of the colon, using the Ultravision Polymer system. The positive reaction rate was 100% for E-cadherin, 98.3% for syndecan-1 and 22.4% for Ets-1 in adenomas, while in carcinomas it was 88.5%, 62.4% and 56.3% respectively. We found decreasing expression of E-cadherin and syndecan-1 throughout colon carcinoma progression and an opposite regulation for the Ets-1 protein. Decrease in expression of syndecan-1 is more pronounced in carcinomas compared to E-cadherin. De novo carcinomas have lower E-cadherin and syndecan-1 expression, and higher Ets-1 expression compared to ex adenoma carcinomas. These findings support the hypothesis that there are differences in the carcinogenesis of these tumors.
The neuroendocrine tumors have heterogenous expression of markers that can be used for their immunophenotyping. Paragangliomas represent neuroendocrine tumors derived from the neural crest, from which also the sympathetic ganglia and adrenal medulla are derived. Paragangliomas are situated outside the anatomical location of the peripheral sympathetic system. They are stained with chrome-containing dyes, therefore they have chromafine cells. Very often, these tumors are producing catechol-derived biogenic amines as are dopamine, epinephrine and norepinephrine. The clinical features of these tumors are dominated by life-threatening blood pressure variations and the localisation is detailed by CT scan, MRI or MIBG scintigraphy. The autonomous production of catecholamines is certified by measurements of their urine metabolites: metanephrine and J. Cell.Mol.Med. Vol 5, No 2, 2001 pp. 311-316 AbstractImmunohistochemistry is part of the routine diagnosis of the neuroendocrine tumors. In our study, we included 52 paragangliomas with various localizations by routine histology and immunohistochemistry. In order to increase the diagnostic specificity, a complex immunohistochemistry panel has been performed consisting of Bcl-2, Ki-67, Bax and Pituitary Adenylate Cyclase-Activating Peptide (PACAP), somatostatin, VIP and Calcitonin Gene Related Peptide (CGRP). After heat induced antigen retrieval, the immunostaining was performed by StreptABC using DAB as a chromogen. We were the first to demonstrate the presence of Bax and PACAP in paragangliomas. Some of the used markers are of prognostic value. The relationship between Bcl-2 and Bax is decisive in generating the final response to the input apoptotic signals. The Ki-67 antigen staining has gained wide acceptance in prognostic evaluation of other tumor types. We noted a small number of Ki-67 positive cases, which signifies a low mitotic activity of these tumors and a relatively high number of Bax positivities (32.9%) and the much lower number of Bcl-2 positivities (11.39%), and could explain the benign behaviour of paragangliomas.
Background: The effects of two lipidlowering drugs, simvastatin and fenofibrate on osteoporosis in the femurs of healthy and ovariectomized female rats were investigated quantitatively by histological images and
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