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M Borg

Publications and source records attributed to M Borg.

31 records · Page 2Linked to original sources
PubMed1989

Semi-late onset and rapidly progressive case of Lafora's disease with predominant cognitive symptoms.

The authors report a sporadic case of Lafora's disease, unusual for the comparatively late age at onset and atypical evolution. Discrete visual phenomena that may be considered as partial seizures occurred at age 19 years. A generalized tonic-clonic seizure occurred at 20 years of age and myoclonus became apparent a few weeks later. A massive cognitive dysfunction was clearly apparent 3 months after the first seizure and further mental deterioration occurred although seizures were controlled by medication and myoclonus remained minimal. The EEG showed the typical association of generalized and focal (occipital) changes. Axillary++ skin and muscle biopsies were positive and easily confirmed the diagnosis. The clinical presentation of Lafora's disease is considered by the authors to be sufficient for a clinical diagnosis, even in such an atypical case. Confirmation by skin biopsy is easily obtainable.

Adult↗
PubMed1988

Production and characterization of monoclonal antibodies against secretory proteinase of Candida albicans CBS 2730.

We describe the production and characterization of three murine monoclonal antibodies (M1-M3) which are directed against different epitopes of the secretory aspartic proteinase of Candida albicans CBS 2730. All antibodies belonged to the IgM class, and they recognized denatured enzyme. Only antibody M1 was capable to react with the active proteinase. Differential reactivity was also observed with a large fragment of the proteinase of C. albicans. All antibodies recognized the corresponding proteinase of C. tropicalis 293 both in the active, and in the denatured state. Denatured porcine pepsin was also recognized by all three antibodies. However, active pepsin was recognized only by antibodies M1 and M2. The antibodies did not inhibit enzymatic activity, and they were not suited for immunofluorescence detection of proteinase on fungal cells. However, employing Western blot analysis, proteinase antigen was detected by antibody M 1 in the serum of a patient suffering from candidal pneumonia. The circulating proteinase antigen was found to be bound to patient's IgM. Implications for the use of monoclonal antibodies in the serodiagnosis of candidosis, and first experiences with other monoclonal anti-proteinase antibodies are discussed.

Antibodies, Monoclonal↗
PubMed1988

Expression of extracellular acid proteinase by proteolytic Candida spp. during experimental infection of oral mucosa.

We traced an acid proteinase from Candida spp. in the initial stages of the pathogenesis of the mycosis. On infection of human buccal mucosa, proteinase antigens were detected by immuno-scanning electron microscopy on the surface of adhering blastoconidia and invading filamentous cells of C. albicans serotype A. Proteinase antigens were also present on blastoconidia of C. albicans serotype B, but were missing on filamentous cells of this serotype. Proteolytic isolates of C. tropicalis behaved like C. albicans serotype A. An isolate of C. parapsilosis did not express the proteinase antigen under conditions of this study. After infection of mucosa, culture medium of C. albicans or C. tropicalis showed a time-dependent accumulation of acid proteolytic activity, indicating that the visualized antigens represent active proteinase. No such activity was detected in the medium of C. parapsilosis. Preliminary experiments with the proteinase inhibitor pepstatin A revealed an 89% reduction of mucosal adherence of C. albicans (serotype A). These results suggest that Candida proteinase is involved in fungal attachment. The pattern of adherence reflects the differential expression of secretory proteinase by different candidal strains.

Candida↗
PubMed1986

Reduction of thrombogenicity in small-diameter vascular prostheses seeded with autologous endothelial cells.

In a canine model small-diameter vascular grafts of knitted Dacron were seeded with autologous endothelial cells. Four weeks after surgery the grafts were removed. Seeded grafts showed a pseudo-intima covered by a monolayer, whereas control grafts showed a cellular lining only at the anastomoses. Graft pretreatment with either fibrin glue or autologous blood in combination with endothelial cell seeding promoted the neointima formation.

Animals↗
PubMed1986

Characterization of a secretory proteinase of Candida parapsilosis and evidence for the absence of the enzyme during infection in vitro.

The opportunistic yeastlike fungi of the genus Candida comprise three species which are proteolytic in vitro. Among them, C. albicans and C. tropicalis are of foremost medical importance. However, a strict correlation between extracellular proteolytic activity and virulence is opposed by the low virulence of the third proteolytic species, C. parapsilosis. We purified the secretory acid proteinase of C. parapsilosis (clinical isolate 265). The enzyme is a carboxyl proteinase (EC 3.4.23) like all other secretory Candida proteinases handled so far. Proteinase 265 is distinguished by a lower molecular weight (approximately 33,000); it has increased hydrophobicity, which accounts for inhibition of the enzyme by hemin, and required the presence of nonionic detergent in the initial steps of purification. The enzyme already undergoes alkaline denaturation at neutrality. Its activity is thus confined to the acid microenvironment of the fungal cell wall. Within this range, the enzyme may degrade immunoglobulins like immunoglobulin A1 (IgA1), IgA2, and secretory IgA. No indication was found for glycosylation of proteinase 265 and the related enzyme of C. albicans CBS 2730. However, the comparable proteinase of C. tropicalis 293 was identified as a manno protein. Antiserum against proteinase 265 cross-reacted strongly with corresponding enzymes from other Candida species. Antisera against proteinases of C. albicans and C. tropicalis reacted only weakly with proteinase 265. Thus, secretory Candida proteinases are likely to possess common and species-specific antigenic sites. In contrast to C. albicans, infection of phagocytes by C. parapsilosis 265 was not accompanied by secretion of fungal proteinase. This lack of induction of the enzyme under conditions of infection may account for the low virulence of most isolates of C. parapsilosis.

Animals↗
PubMed1984

A colorimetric assay for the assessment of cytotoxicity of yeasts.

A colorimetric assay for the quantitation of microbial cytotoxicity has been developed using cells from a monocyte-like human cell line (U937), epithelial cells (Hela), and fibroblast-like cells (Vero) as targets. The fraction of surviving cells was determined by their content of the dye neutral red which is retained only by live cells and can be quantitated photometrically after controlled lysis. The neutral red retention assay was at least as sensitive as the 51Cr-release assay; it was considerably less laborious, faster, and avoided handling of radioactivity. Among the different Candida species tested, the highest cytotoxicity was associated with C. albicans and C. tropicalis; a lower degree of cytotoxicity was exhibited by C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. pseudotropicalis. Among the strains of a given fungal species cytotoxicity varied by up to 40%.

Animals↗
PubMedDate not supplied

[Comparison of various immune surface labeling methods for scanning electron microscopy with the example of a surface antigen protein of the yeast Candida albicans].

The labeling of immunocomplexes for scanning electron microscopy (SEM) is a fairly new technique, and the various procedures, that have been proposed, have not yet been compared. Such comparative evaluation was performed with Candida protease as a target antigen. This secretory enzyme of the opportunistic yeast Candida albicans can be localized on the surface of fungal blastopores and mycelia, both after growth in proteinaceous medium and upon infection of murine peritoneal macrophages. The presence of the protease antigen was confirmed by immunofluorescence and by immunoperoxidase-light microscopy. The decoration of protease - anti protease complexes for SEM was attempted with colloids derived from the immunoperoxidase reaction, by the immunogold technique, and by antibodies linked to beads of synthetic polymers (polystyrene, polymethacrylate, polyacrolein). In addition, inactivated Staphylococcus aureus was used, which binds to antibodies through its protein-A. The high resolution by SEM of surface structures was matched only by the colloid based decoration techniques. All conjugates with beads suffered from inconsistent binding, which did not correspond with the distribution of the surface antigen. The comparatively best result with beads was obtained with polystyrene (Latex). Colloid based techniques in addition allow for critical point drying, which cannot be applied to synthetic beads in the usual manner.

Acrolein↗
PubMedDate not supplied

[Malignant systemic angioendotheliomatosis. Apropos of a case with an ultrastructural and histo-immunologic study].

Clinico-pathological data in a typical case are compared with those of 54 published reports of systemic angioendotheliomatosis. In this rare disease the lesions, characterized by clusters of abnormal cells in the small vessels, usually have multivisceral localizations, with chiefly cutaneous and encephalic manifestations and a rapidly fatal course. However cases are known with lesions restricted to the skin and a protracted if not regressive course; about half of these cases are associated with an endocarditis. In the case reported, the results of ultrastructural and histo-immunological studies (f. VIII, lysozyme, anti-protease, Ig) are in favour of the endothelial origin of the abnormal cells, a now widely accepted hypothesis.

Aged↗