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Biomedical subjects

D W Mackenzie

Publications and source records attributed to D W Mackenzie.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1988

Meningitis caused by Absidia corymbifera.

A 56-year-old man developed mucormycotic meningitis caused by Absidia corymbifera and which followed a penetrating head injury. Antibodies to it were detected in the cerebrospinal fluid at titres higher than those found in the serum, thereby suggesting local production of antibody in the subarachnoid space.

Antibodies, Fungal↗
PubMed1988

Pyrolysis mass spectrometry as a method for inter-strain discrimination of Candida albicans.

A claim that Candida albicans strains NCPF 3153 and B311 were identical was investigated. Authentic strains were shown to be distinct (P less than 0.1%) by pyrolysis mass spectrometry (PyMS). Of twelve strains, provided as clones of NCPF 3153, seven were authenticated, one yielded an equivocal result and four were distinct from both NCPF 3153 and B311. Of eight B311 clones, six were authenticated and two yielded equivocal results. Although five non-C. albicans yeast strains were identified as distinct from B311 and NCPF 3153, Torulopsis glabrata NCPF 3240 was identified as B311, and one clinical isolate of C. albicans as NCPF 3153. This could be explained by the specificity of the mathematical analysis for discrimination between the authentic strains.

Candida albicans↗
PubMed1987

Strain differentiation of Candida albicans by morphotyping.

Strains of Candida albicans can be differentiated by the morphological features of streak colonies developed on malt agar. A morphotyping system is proposed, where numerical codes are assigned primarily on the basis of the nature and extent of marginal fringing and the surface topography of the streak colony. The system allows ready differentiation to be made of morphotypes, requires no specialized equipment or expertise and provides a simple and reproducible means for epidemiological studies of candida and candidosis.

Candida albicans↗
PubMed1987

[Biological diagnosis of candidiasis].

The methods which can be applied to the biological diagnosis of candidiasis are considered from a practical point of view. They are the histological examination, mycological methods of isolation and identification and serological technics leading to the detection of antibodies and antigens. For each method, the recent progress which have already been evaluated on a large scale in routine, have been considered. This makes it possible to bring out their interest and their limits. These considerations leads us to suggest the approach to the biological diagnosis of Candidiasis.

Candidiasis↗
PubMed1987

Emericella nidulans in a maxillary sinus fungal mass.

Sexual reproductive stages of fungi are very rarely found within mammalian tissues. We report here coexistence of cleistothecia associated with Emericella nidulans and its conidial state, Aspergillus nidulans, in a fungal mass which developed in a maxillary sinus.

Aged↗
PubMed1987

Evaluation of a test to detect circulating Aspergillus fumigatus antigen in a survey of immunocompromised patients with proven or suspected invasive disease.

An ELISA for the detection and measurement of Aspergillus antigenaemia has been developed and evaluated by examining sera submitted over a 12-month period from immunocompromised patients with a likelihood of invasive aspergillosis. Results from proven cases of invasive aspergillosis confirmed at post-mortem and specimens from individuals with suspected disease showed that tests on single serum samples were often negative. Multiple specimens from the same patient greatly increased the frequency of detection. Repeated monitoring of sera from a single patient showed wide fluctuations in antigen level, which was considered to be due partly to the medical regimen to which the patient was subject. Control sera from healthy laboratory personnel were consistently negative, but a number of 'at-risk' patients without other evidence of invasive aspergillosis sometimes had low amounts of antigen. Concentrations of Aspergillus antigen of 100 ng ml-1 or higher were considered to be strongly suggestive of fungal invasion.

Animals↗
PubMed1986

Aspergillus fumigatus antigens used in the serodiagnosis of aspergillosis.

The diagnostic antigens in Aspergillus serology are mycelial or culture filtrate concentrates. Recent work has been directed towards the separation of defined, reproducible products of greater sensitivity and specificity than crude extracts. Conventional methods of separation have been used; they include fractional precipitation, detergent extraction, chromatography, and preparative isoelectric focusing. Selective staining of the separated fractions has shown many of the more reactive components to be glycoproteins. Affinity binding to Concanavalin A has demonstrated the presence in these of alpha-D-glucopyranose, alpha-D-mannopyranose and/or terminal alpha-D-N-acetylglucosamine. Major amino acid constituents are serine and threonine, together with glutamic and aspartic acids. The more reactive and specific components, as judged by their antibody binding capacity, have molecular weights greater than 70,000; in some cases they are as high as 150,000 to 180,000. Isoelectric focusing gave products with acidic pI values which specifically bound the IgG present in sera from aspergillosis patients. Results from a number of laboratories suggest that a group of acidic glycoproteins constitute the most promising source of a diagnostic reagent for aspergillosis. However, further analysis and a comparison of these substances in an international collaborative study is needed before agreement can be reached on a "standard" antigen preparation.

Animals↗