PubMed Health⌕ Search

Biomedical subjects

D Arvanitis

Publications and source records attributed to D Arvanitis.

At least 37 records · Page 2Linked to original sources
PubMed1995

Effect of trimethoprim-sulphamethoxazole in Langerhans' cell histiocytosis: preliminary observations.

Twenty-three children with Langerhans' cell histiocytosis (LCH) have been treated with trimethoprim-sulphamethoxazole (T-S) in a 4-year period. The children are classified in two main groups according to the extent of their disease. Group A includes 16 children with single system disease and group B, seven children with multisystem disease. All patients were treated for 4 weeks to 3 months. The results of treatment are evaluated in terms of response in individual organs involved. All children with single system disease had a good response to the drug. Children with multisystem disease had a good response to some organs but a poorer outcome for the lungs and for the blood. These patients did not respond even to conventional chemotherapy.

Child↗
PubMed1993

Histochemical marker of human catecholamine neurons in ganglion cells and processes of a temporal lobe ganglioglioma.

A temporal lobe ganglioglioma was surgically removed from an 8-year-old boy who had developed temporal lobe paroxysmal convulsions. The present study describes staining reactions of the ganglioglioma tissue with histochemical methods designed to demonstrate the protein bodies, which are markers of catecholamine neurons in humans. Brookes' procedure for basic proteins and rhodamine B for lipids showed identical staining of the following: (1) spherical inclusion bodies in the neoplastic neurons, (2) large eosinophilic globules in the dilated neuronal processes, and (3) the protein bodies in the neurons of human locus ceruleus and sympathetic ganglion. We conclude that the catecholamine neurons of the ganglioglioma possess the same marker of aminergic identity as normal catecholamine neurons in humans. Thus, this marker could be used as an additional diagnostic tool for the identification of this type of tumor.

Biomarkers, Tumor↗
PubMed1992

Myelin palingenesis. 1. Electron microscopical localization of myelin/oligodendrocyte proteins in multilamellar structures by the immunogold method.

The issue of the capacity of mature oligodendrocytes to remyelinate naked axons has not been totally resolved. The impression is that for this to happen, oligodendrocytes have to undergo cell division. We are interested in providing an answer to the question: can oligodendrocytes myelinate more than once? To address this question, we are using a model system consisting of pure cultures of postmyelination oligodendrocytes. We have previously shown that these cells have plasticity and are able to regenerate, but for this to occur they need a signal. In vitro, this signal is provided by interaction with a positively charged substratum and a serum factor(s). Over time in culture, without cell division, oligodendrocytes assemble multilamellar structures that ultrastructurally resemble myelin. We have named this process myelin palingenesis--rebirth--to distinguish it from remyelination. In order to ascertain the significance of the regenerative process observed in vitro and its predictive value as to the capabilities of oligodendrocytes to ensheathe axons, we undertook an ultrastructural and immunocytochemical characterization of the multilamellar membranes to assess whether they contain all the myelin-characteristic proteins, i.e., myelin basic protein, proteolipid protein, 2',3'-cyclic nucleotide 3'-phosphodiesterase and myelin-associated glycoprotein. We have used antibodies against these proteins as immunocytochemical probes in conjunction with the immunogold method at the electron microscopic level. Oligodendrocyte cultures were processed for electron microscopy. Blocks were serially sectioned parallel to the culture plate at 0.09-micron spacings. Staining of cells was done prior to embedding. Analysis of these micrographs brought to light the existence of membrane-membrane interaction between multilamellar structures; this is reminiscent of the interactions observed in situ between myelinated axons. We have found that the membranous structures possess all the myelin-characteristic proteins. Furthermore, based on the accessibility of these proteins to the antibodies, e.g., whether or not permeabilization was required, we can surmise that these proteins are incorporated into the membranous structures with the same orientation as in myelin. These results, in conjunction with our earlier work, show that mature oligodendrocytes stripped of their myelin are able to regenerate and reassemble multilamellar membranes that have all the myelin proteins. It remains to be proven that when provided with axons, these oligodendrocytes will generate typical myelin.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed1992

Myelin palingenesis. 2. Immunocytochemical localization of myelin/oligodendrocyte glycolipids in multilamellar structures.

Myelin is a membrane with unique characteristics that set it apart from any other membrane. It has a very high lipid:protein ratio (approximately 75:25) not found in other multilamellar membranes; it has a high content of two glycolipids--galactocerebrosides and sulfatides--which account for 26.5% of its lipids. The physiological role of these glycolipids in myelin and/or oligodendrocytes is unknown, but evidence that Abs directed against them interfere with myelination has been presented. Moreover, one of the early events in the process of oligodendrocyte differentiation prior to myelination is the acquisition of galactocerebroside on their surface. In earlier work, we have demonstrated that adhesion of oligodendrocytes to a positively charged substratum signals the commencement of myelinogenesis. Among the events that take place following adhesion are the rapid synthesis of glycolipids. Since over time in culture, oligodendrocytes elaborate multilamellar membranes that contain all the myelin characteristic proteins, we undertook to investigate whether these structures also accumulate myelin characteristic glycolipids. We have used three monoclonal antibodies--two are directed against galactocerebroside, the third one is an antisulfatide--in conjunction with the immunogold method, at the electron microscopic level, to examine the distribution of these glycolipids in the multilammelar structures that accumulate in long-term oligodendrocyte cultures. Our data show that galactocerebrosides and sulfatides are present in the multilamellar structures. Staining is easily demonstrated on the outermost membrane. However, as was the situation with myelin proteins, detection of these glycolipids on the inner lamellae is only achieved at the expense of destroying the ultrastructure. This is so, independent of whether the structures are compact or not.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗