Search PubMed⌕ Search

Biomedical subjects

R Laschi

Publications and source records attributed to R Laschi.

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

Basement membrane production by hepatocytes in chronic liver disease.

The immunohistologic distribution of fibronectin, laminin, type IV collagen and whole basement membrane was evaluated in liver biopsies from patients with chronic active liver disease. Fibronectin was consistently increased in the areas of piecemeal necrosis, portal tracts and fibrous septa. Laminin was not detected in normal liver parenchyma. In contrast, laminin positive linear basement membrane structures were prevalent in portal tracts, fibrous septa and the peripheral sinusoids of cirrhotic nodules. In areas of piecemeal necrosis, the hepatocytes, single or assembled in "rosettes", were frequently underlined by linear deposits of laminin and type IV collagen. This immunoreactivity was often polarized, being confined to the stromal side of liver cells, while the parenchymal side was negative for both proteins. Electron microscopy revealed a typical basement membrane in corresponding areas. Hepatocytes normally do not produce a basement membrane, but do so following chronic injury. We suggest that the polarized basement membrane accumulation by hepatocytes is a hallmark of hepatocyte regeneration following damage.

Basement Membrane↗
PubMedDate not supplied

Ultrastructural and immunohistochemical contribution to the histogenesis of human cardiac myxoma.

The ultrastructural features of 8 human cardiac myxomas were analyzed and correlated with immunohistochemical data, with the aim to clarify the characteristics of the cell lines involved in the tumor genesis. Immunohistochemical studies were performed to detect the presence and the distribution of intracytoplasmic filaments (vimentin, desmin, actin, myosin) as well as myoglobin and factor VIII-related antigen, albumin, and lysozyme. Eighty percent of myxoma cells were simultaneously positive for vimentin, desmin, and actin, whereas 30% of them stained with antifactor VIII and antivimentin antibodies. The submicroscopic analysis revealed two main cell populations: (1) one composed of stellate-shaped cells with scanty organelles and sparse hyaloplasmic filaments scattered throughout the myxoid stroma and forming a loose network with their projections; (2) another one included cells with more cytoplasmic organelles, intermediate filaments, and myofilaments arranged either singly or in both solid and hollow cord-like structures. Our results support the hypothesis that cardiac myxoma may originate from a reserve multipotent mesenchymal cell able to differentiate more or less completely along two major evolutional lines: myoid and endothelial. The tumor tissue thus seems to be involved in vessel formation, suggesting a growth pattern akin to that manifested in other forms of endocardial pathological reactivity in which reserve mesenchymal cells are engaged.

Adult↗
PubMedDate not supplied

Elastofibroma: an in vivo model of abnormal neoelastogenesis.

Thirteen cases of elastofibroma have been studied by conventional light and electron microscopy, as well as by histochemistry and immunohistochemistry. By light microscopy elastinophilic material appeared as huge fibers crossing collagen bundles. Immunohistochemistry demonstrated a strong positivity for elastin in numerous and circumscribed areas of the extracellular matrix. By electron microscopy, collagen consisted of 40-50-nm wide fibrils, and elastin was made of large aggregates of moderately electron-dense material surrounding a very thin, apparently normal, elastin core. At high magnification these aggregates consisted of short tubules, often in regular arrays, surrounded by microfibrils and microfilaments. These data, associated with selective digestions on thin sections with elastase, purified collagenase, hyaluronidase, and chondroitinase ABC, revealed that elastic fibers in elastofibroma seem to be made of true elastin surrounded by an enormous amount of hydrophilic material, in which some elastin, chondroitin sulfates, and collagenase type-VII sensitive material are aggregated forming a rather ordered array of short tubules.

Adult↗
PubMedDate not supplied

Ependymoma of the foramen of Monro: ultrastructural characterization.

The characteristics of clear cells of an ependymoma of the foramen of Monro have been studied by electron microscopy to precisely define its organellar composition and to establish the tumor histogenesis. Our data confirm that the once-thought oligodendroglial is, in fact, an ependymal tumor. Both the scarce number of organelles, owing to the low degree of differentiation, and the abundance of hyaloplasmic lipid vacuoles can account for the clear appearance of these tumor cells.

Adult↗
PubMedDate not supplied

Ultrastructural localization of ConA and WGA receptors on human corneal endothelium.

Corneal endothelial cell plasma membrane plays an important role in maintaining normal thickness and transparency of the cornea. We investigated the molecular organization of endothelial cell membrane using lectins labeled with colloidal gold as ultrastructural probes. We detected the presence of Concanavalin A and Wheat Germ Agglutinin which recognize specific carbohydrate residues of membrane glycoconjugates. We think that this fine cytochemical approach may be useful to better understand the transport mechanisms between aqueous humor and corneal endothelium and to study adaptation and aging of corneal endothelial cells.

Concanavalin A↗