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D W Mackenzie

Publications and source records attributed to D W Mackenzie.

At least 19 recordsLinked to original sources
PubMed1992

Cytological immunodetection of yeast glycoprotein secretion.

Expression of antigenic epitopes shared by secreted yeast glycoproteins was studied using specific immunological probes. Application of cytological and ultrastructural methods of immunodetection, employing monoclonal antibodies, permitted us to localize these glycoproteins in the cytoplasm, through the cell wall and at the yeast cell surface. Importance of glycosylation-secretion relationships were evaluated in the secretion process of these molecules. The cell wall crossing and the cell surface distribution of antigenic glycoproteins was described in immunoelectron microscopy and immunofluorescence. Some preferential secretion "ways" were suspected through the yeast cell wall leading to an heterogenous distribution of cell surface glycoproteins destined to be excreted into the medium. Antigenic variability of cell wall glycoproteins expression was discussed in relation with the glycoprotein secretion.

Antibodies, Monoclonal↗
PubMed1992

Evaluation of an enzyme immunoassay using neoglycolipids constructed from Candida albicans oligomannosides to define the specificity of anti-mannan antibodies.

In order to study the respective roles of oligomannoside sequences in the antigenicity of Candida albicans phosphopeptidomannan, a method was developed for constructing neoglycolipids from oligomannosides released by depolymerisation of this molecule. Oligomannosides released by acetolysis were converted to neoglycolipids by coupling them to 4-hexadecylaniline in an equimolar reaction checked by thin layer chromatography. When coated onto microEIA plates, the neoglycolipids exhibited strong reactions which were dose dependent and were saturable with concanavalin A. Reactivity of neoglycolipids with immunoglobulins were then tested with a panel of monoclonal and polyclonal antibodies reacting with epitopes present in the original phosphopeptidomannan. One of two IgM monoclonal antibodies and two of five monospecific rabbit polyclonal IgG reacted strongly with neoglycolipids therefore providing evidence of the presence of structures mimicking epitopes within the pool of neoglycolipids. When 38 sera from 18 hospital inpatients with various levels of antibodies to Candida albicans were tested, a correlation was observed between the EIA to detect neoglycolipids and the EIA to detect phosphopeptidomannan. Successive sera from all patients showing seroconversion in the immunofluorescence assay had increased EIA signals for neoglycolipids.

Antibodies, Fungal↗
PubMed1992

Analysis of Aspergillus fumigatus catalases possessing antigenic activity.

Analysis of Aspergillus fumigatus water soluble fractions by electrophoresis on non-denaturing polyacrylamide gels (PAGE) showed the presence of at least three catalase bands. They were designated F, S1 and S2 in order of descending electrophoretic mobility with respect to the anode. The multiple enzyme forms appear to be distinct in their physicochemical properties. Enzyme bands S1 and S2 were simple catalases; the F band had an additional peroxidase function. All of the components were antigenic and differed in their binding to specific antibodies raised in rabbits with separate fractions of A. fumigatus mycelium. When serum from patients with aspergilloma, allergic bronchopulmonary aspergillosis, cystic fibrosis and chronic asthma were pre-incubated with A. fumigatus antigens and analysed by PAGE, 17 of 26 samples either abolished or reduced catalase activity. Enzyme F was a non-Concanavalin A (ConA)-binding antigen; the S1 and S2 enzymes were ConA-binding glycoprotein antigens. The major catalase band present in A. niger preparations represented only a minor component in A. fumigatus.

Animals↗
PubMed1992

Specific recognition pattern of IgM and IgG antibodies produced in the course of experimental paracoccidioidomycosis.

Specific IgM and IgG responses to Paracoccidioides brasiliensis produced in resistant and susceptible mice during experimental paracoccidioidomycosis were examined by the immunoblotting procedure. Sera from infected mice recognized 51 antigen bands with apparent molecular masses from 8 to 86 kD. Sixteen of these were defined as major antigen bands because of almost universal presence of antibodies to them, and their intense staining. All sera, including those from normal control mice, tested for both IgM and IgG antibody reacted with the major E antigen which appeared as a large diffuse band from 43 to 47 kD. Comparisons between resistant and susceptible mice showed some significant differences in IgM responses to many antigen bands. While IgG responses were quite similar for both strains, differences were apparent in the response to the antigens at 62 and 68 kD.

Animals↗
PubMed1992

Presence of human antibodies reacting with Candida albicans O-linked oligomannosides revealed by using an enzyme-linked immunosorbent assay and neoglycolipids.

In order to study the presence of antibodies directed against Candida albicans O-linked oligomannosides (oligomannosides O) in patient sera, we have developed an enzyme-linked immunosorbent assay (ELISA) involving neoglycolipids constructed with these residues (NGLO). Oligomannosides O released by mild alkaline degradation of the C. albicans cell wall phosphopeptidomannan (PPM) contained one to seven mannose residues, among which the quantitatively major components, mannobiose and mannotriose, were shown by 1H nuclear magnetic resonance to contain exclusively alpha (1-2) linkages. The pool of oligomannosides was converted to neoglycolipids by coupling them to 4-hexadecylaniline in an equimolar reaction checked by thin-layer chromatography. We have tested against these neoantigens, coated on ELISA plates, 15 pairs of sera corresponding to individual seroconversions observed in 15 patients during the course of a mycological and serological survey of candidiasis. For all patients, seroconversions resulted in an increased level of antibodies against NGLO. A significant correlation was observed between the results of ELISA-NGLO, ELISA involving the original PPM molecule, and routine antibody detection tests, indirect immunofluorescence assay, and cocounterimmunoelectrophoresis. These results therefore demonstrate the synthesis of human antibodies reactive with oligomannosides O constitutive of the C. albicans mannan molecule which have been previously described as exhibiting an inhibitory effect on human lymphocytic proliferation.

Antibodies, Fungal↗
PubMed1991

Isoenzyme changes in Candida albicans during domestication.

Isoenzyme analysis was performed on multiple strains of two commonly used reference cultures of Candida albicans (B311 and NCPF3153). Whereas strains originating from C. albicans B311 showed no variation in isoenzyme profiles, some strains derived from NCPF3153 were identical to B311 strains but others showed variation in their glucose-6-phosphate dehydrogenase isoenzymes. The results are compared with those from previous analyses with these strains and show that C. albicans can undergo genetic alterations during prolonged maintenance in laboratories.

Candida albicans↗
PubMed1990

Value of detection of antibodies to Candida albicans germ tube in the diagnosis of systemic candidosis.

To test the value of detection of anti-Candida albicans germ tube antibodies by indirect immunofluorescence assay in the diagnosis of systemic candidosis, a retrospective study was done using 126 sera from 27 patients with presumptive systemic candidosis (13 immunocompromised), 165 sera from 45 patients with aspergillosis (29 immunocompromised), 35 sera from eight patients with cryptococcosis (6 immunocompromised), and 101 sera from 101 blood donors. While 21 of 27 patients with systemic candidosis (77.8%) had anti-germ tube antibodies, these antibodies were absent in all patients with cryptococcosis and in all blood donors. They were however detected in 5 of 45 patients with aspergillosis (11.1%). Ten of 13 (76.9%) immunocompromised patients with candidosis had anti-germ tube antibodies; similar results were obtained in immunocompetent patients with candidosis (78.6%). The specificity was 96.8%, indicating a high degree of discrimination was possible between systemic candidosis and other invasive mycoses in the patients studied. Anti-germ tube responses did not appear to be significantly reduced in immunocompromised patients.

Antibodies, Fungal↗
PubMed1990

Evaluation of a gold-silver staining method for detection and identification of Candida species by light microscopy.

A gold-silver staining procedure was evaluated for detection of Candida species of medical importance. Probes were prepared by coupling lectins or antibodies (polyclonal and monoclonal) directly or indirectly to colloidal gold particles. Structures reacting to these probes were specifically revealed by light microscopy in cells present in infected kidney tissue sections or in isolated yeast cells on glass slides. Definition, contrast and sensitivity were of a high order. Preliminary data showed that it was possible, using discriminating dilutions, to identify cells from different species of the genus Candida, grown in vitro, according to their ability to stain with polyclonal monospecific antisera. The advantages of gold-silver staining compared with other staining procedures currently used in routine mycological laboratories are its sensitivity, good definition, ease and rapidity, and long conservation of reaction. It is suggested that the procedure has applications for research and identification of yeasts in clinical samples.

Candida↗
PubMed1990

Comparison of antigens from agents of actinomycetoma by immunodiffusion and electrophoresis procedures.

Antigenic extracts were prepared from culture filtrates of the principal agents known to cause actinomycetoma, namely Actinomadura madurae, Actinomadura pelletieri, Nocardia asteroides, Nocardia brasiliensis, Nocardia otitidis-caviarum, and Streptomyces somaliensis. These antigenic preparations were compared by immunodiffusion (ID), counterimmunoelectrophoresis (CIE), line immunoelectrophoresis (LIE) and rocket line immunoelectrophoresis (RLIE), with rabbit antisera prepared against each of the extracts. Cross-reactivity between antigenic extracts from the different actinomycetes, measured by determining the number of precipitin lines in homologous and heterologous systems, was common. Reactions were always stronger and more precipitin lines were present when antigenic extracts were tested against homologous antisera. Similarities between A. madurae and A. pelletieri antigens were of a low order and cross-reactivity did not exceed 33%. A. pelletieri resembled N. asteroides more closely than A. madurae, with 44% of detectable antigenic components cross-reacting. The three species of Nocardia had common antigenic epitopes, but the overall degree of similarity was of a low order (between 12 and 27% by LIE and RLIE). Antigenic extracts of S. somaliensis had few components in common with the other species tested and only one of the 34 lines present in the RLIE system for N. asteroides showed any reaction of identity with an antigenic component in the S. somaliensis extract. Single cross-reacting lines were also present in the CIE and LIE systems.

Actinomycetales Infections↗
PubMed1990

Immunochemical studies of Aspergillus fumigatus mycelial antigens by polyacrylamide gel electrophoresis and western blotting techniques.

Differences were detectable among strains of the opportunist fungal pathogen Aspergillus fumigatus when water-soluble (WS) preparations were analysed by combined SDS-PAGE and Western blotting procedures. A wide range of molecules of apparent molecular masses from approximately 20 to greater than 100 kDa showed specific binding to antibodies raised in rabbits to A. fumigatus wall and cytoplasmic components. The ability to bind antibody was markedly reduced by treatment of these antigens with sodium periodate or with specific proteases or glucanases. Pretreatment of blotted antigens with either concanavalin A (ConA) or wheat germ agglutinin (WGA) did not, however, inhibit subsequent antibody binding. The antigens of subfractions prepared from a single strain of A. fumigatus WS material were also susceptible to periodate oxidation and enzymic hydrolysis. Slight cross-reactivity was apparent when crude preparations of cellular or culture filtrate antigens, used in this laboratory to detect antibodies to Candida albicans, Coccidioides immitis and Cryptococcus neoformans, were probed with hyperimmune rabbit antisera to A. fumigatus. Efforts were made to characterize the WS preparations of A. fumigatus, used as diagnostic antigens in many laboratories. The electrophoretically separated antigenic moieties were shown to be predominantly glycoproteins. Binding of cytoplasmic antigens to antibodies raised to wall material showed the presence of many common components in both wall and cytosol. Antiserum to wall components revealed most differentiation among A. fumigatus strains.

Antigens, Fungal↗
PubMed1990

Immunoreactivity of neoglycolipids constructed from oligomannosidic residues of the Candida albicans cell wall.

To establish a model to study the immunoreactivity of oligosaccharidic structures from the Candida albicans cell wall, we attempted to construct neoglycolipids with these residues by using oligomannosides released after mild acid hydrolysis of the phosphopeptidomannans isolated from yeast forms. From a mixture of manno-oligosaccharides ranging from mannobiose to mannononaose, the structure of a quantitatively major component (mannotriose) was determined to be Man (beta 1-2) Man (beta 1-2) Man alpha by 1H nuclear magnetic resonance analysis. After coupling of the pool of oligosaccharides to a lipid (4-hexadecylaniline), the synthesized molecules were injected into mice and rats. Antibody responses were detected on enzyme-linked immunosorbent assay plates coated with either phosphopeptidomannans or neoglycolipids. The hybrid molecules exhibited both immunogenicity and antigenicity. The kinetics of antibody responses as well as immunofluorescence patterns observed on whole C. albicans cells strongly mimicked results from the immunization of animals with natural antigens. Construction of neoglycolipids could therefore provide an interesting approach to the study of specific oligosaccharides of C. albicans and their recognition by the host immune system.

Animals↗
PubMed1989

Studies on antigens from agents causing black grain eumycetoma.

Culture filtrate and cellular antigens prepared from 14 agents which cause black grain eumycetoma were compared by double diffusion and immunoelectrophoresis. The fungal agents studied included five isolates of Madurella grisea, two of Madurella mycetomatis and a single isolate each of Pyrenochaeta mackinnonii, Pyrenochaeta romeroi, Chaetosphaeronema (Pseudochaetosphaeronema) larense, Plenodomus avramii, Phoma/Phyllosticta, Aureobasidium (Exophiala) mansonii and Leptosphaeria senegalensis. Cross-comparisons between all paired combinations of antigens and rabbit antisera raised against each antigen, before and after absorption with heterologous antigens, were expressed as percentage homologies. Cross-reactivity was marked (up to 90%) within the M. grisea group and between M. grisea and P. mackinnonii, but not with P. romeroi. The results suggest that the representatives of the M. grisea group tested were similar or identical to P. mackinnonii. Little antigenic similarity was observed between M. grisea and M. mycetomatis. The remaining antigens and antisera reacted most strongly with their homologous counterparts, except for L. senegalensis which had antigens in common with M. grisea (0-55% homology) and P. mackinnonii (70% homology). Analysis of the antigenic patterns derived from five of six unidentified isolates from patients with black grain eumycetoma showed marked similarity to M. grisea and P. mackinnonii.

Antigens, Fungal↗
PubMed1989

Morphotype markers of virulence in human candidal infections.

A study of the morphotypes of 446 strains of Candida albicans, isolated from a variety of clinical specimens, is reported. The method was based on a morphotyping scheme that has recently been described, but not all of the potential characters were used in this analysis. By this limited code, 50 different morphotypes were distinguished, the largest group comprising 23% of the population. The simplicity and good discrimination of the method make it a useful typing scheme for C. albicans. Discontinuous colonial fringes were associated with strains from oral sites and deep infections. Significantly, 67% of strains from fatal infections were of the discontinuous fringe type, compared to only 11% of strains from other infections. Further associations between morphotype and anatomical source included narrow-coarse fringes in genitourinary isolates.

Candida albicans↗