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Biomedical subjects

D W Mackenzie

Publications and source records attributed to D W Mackenzie.

At least 55 records · Page 3Linked to original sources
PubMed1984

DNA homology studies in the taxonomy of dermatophytes.

The taxonomy of the dermatophyte genera Trichophyton, Microsporum and Epidermophyton was investigated by determinations of DNA homology. DNA extracted from 10 isolates (seven species) of dermatophytes was reannealed by hydroxyapatite chromatography. DNA homology levels of 65-80% corresponded to species within a single genus. There was a general agreement with established classification, particularly in assigning species to separate genera. DNA from the Trichophyton state of Arthroderma benhamiae (NCPF 456) showed 71 and 76% homology with DNA from T. mentagrophytes (NCPF 224) and T. rubrum (NCPF 5034) respectively. T. terrestre showed low homology (25%) when compared with the other species of dermatophytes tested.

Arthrodermataceae↗
PubMed1984

Specificity of antigens from pathogenic Aspergillus species. I. Studies with ELISA and immunofluorescence.

Studies were made by enzyme linked immunosorbent assay (ELISA) and indirect fluorescent antibody (IFA) tests on the reactivities and specificities of 13 antigens prepared from four species of Aspergillus against antisera from immunized rabbits and 64 sera from patients with aspergillosis, other systemic mycoses and nocardiosis. Although reactions in both serological tests were invariably strongest with homologous antigen: antibody systems, antisera from rabbits immunized with A. fumigatus, Blastomyces dermatitidis, Candida albicans and Paracoccidioides brasiliensis reacted in the ELISA test with all of the Aspergillus antigens. In contrast, cross-reactivity was virtually non-existent with antiserum to Histoplasma capsulatum. Of five antigens prepared from A fumigatus tested by ELISA against human sera from patients with aspergillosis and other nocardial and systemic fungal infections, sensitivities varied from 81 to 100% for sera from 32 patients with aspergillosis, and specificities from 20 to 97% for sera from 30 patients with nocardiosis and other systemic mycoses. Purified A. fumigatus C antigen reacted weakly with sera from eight of these 30 patients, but the reactions were readily distinguishable from those obtained with sera from patients with aspergillosis. At optimal serum dilutions, cross-reactivities of A. fumigatus in the IFA studies were non-existent in the sera from 28 patients with candidosis, coccidioidomycosis, cryptococcosis, histoplasmosis, paracoccidioidomycosis and nocardiosis. Sensitivities of IFA were 94% for patients with aspergilloma and 83% for patients with allergic bronchopulmonary aspergillosis.

Animals↗
PubMed1984

Specificity of antigens from pathogenic Aspergillus species. II. Studies with line immunoelectrophoresis.

Somatic (mycelial) and metabolic (culture filtrate) antigens of Aspergillus flavus, A. fumigatus, A. nidulans, A. niger and A. terreus were compared by line immunoelectrophoresis with sera from patients with allergic bronchopulmonary aspergillosis (ABPA) or aspergilloma, or from immunized animals. Number of lines observed when tested with human sera were similar for somatic and metabolic preparations of A. fumigatus, but up to 33 lines were present when both types of antigens were tested simultaneously. Cross-reactions between heterologous antigens and sera from patients with aspergilloma or ABPA were uncommon. In contrast, cross-reactions were common when standard antisera prepared in animals against heterologous species of Aspergillus were tested against A. fumigatus antigens. Lines of identity between homologous antigens and those from A. fumigatus were observed in 5 of 9 lines obtained with A. flavus, 4 of 16 lines of A. nidulans, 4 of 9 lines of A. niger and 4 of 8 lines of A. terreus.

Animals↗
PubMed1982

The histopathological features of pale grain eumycetoma.

Histological findings in 24 cases of pale grain eumycetoma have been compared. The inflammatory response and morphology of grains caused by different organisms are very similar. However the histological appearances of Neotestudina rosatii infections, although reminiscent of dermatophyte mycetomas, are distinctive. The characteristic features include the presence of cement and the short swollen hyphal segments. Petriellidium boydii grains are more likely to contain numerous vesicles or swollen hyphae and be surrounded by a prominent eosinophilic fringe. In contrast, Fusarium and Acremonium grains usually have a minimal fringe and contain a dense mass of intermeshing hyphae. However the features separating P. boydii and Fusarium/Acremonium grains are not invariable and can only be used as an approximate guide to the correct identity of the organism.

Eosinophils↗
PubMed1981

Analysis of wall antigens of Aspergillus fumigatus by two-dimensional immunoelectrophoresis.

Water-soluble and surface-located antigens from Aspergillus fumigatus mycelium were analysed by two-dimensional electrophoresis (2D IEP) with selected sera. A complex pattern was seen when a water-soluble fraction reacted with hyperimmune sera. Significantly fewer precipitin peaks were seen when wall-located antigens were used in the 2D IEP system; this made possible the detection of a small number of recurring antigen-antibody interactions when sera from patients with aspergilloma or allergic bronchopulmonary aspergillosis were analysed. Many of these recurring precipitates were affected by lectins with specificity for alpha-D-glucose, alpha-D-mannose or N-acetyl-D-glucosamine. All the antigens were susceptible to hydrolysis by pronase, confirming the glycoprotein composition of many of these macromolecules.

Animals↗
PubMed1981

Responses of human peripheral lymphocytes to soluble and insoluble antigens of Candida albicans.

Responses of peripheral lymphocytes from the blood of 20 healthy volunteers were determined in vitro by measurement of tritiated thymidine uptake in the presence of six different antigens prepared from Candida albicans. Crude antigens (disintegrated cells, culture filtrate) produced greater lymphoblast reactivity than purified preparations (cytoplasmic proteins, cell-wall mannan). Reactions to soluble mannan were uncommon but the number of subjects who responded to them increased from one to 14 when the material was rendered particulate by adsorption on to latex particles. Lymphocyte responses were also elicited by intact, heat-killed yeast cells.

Antigens, Fungal↗
PubMed1980

Deoxyribonucleic acid base compositions of dermatophytes.

DNA was extracted and purified from 55 dermatophyte isolates representing 34 species of Trichophyton, Microsporum and Epidermophyton. The base compositions of the chromosomal DNA were determined by CsCl density gradient centrifugation and were found to be in the narrow range of 48.7 to 50.3 mol % G + C. A satellite DNA component assumed to be of mitochondrial origin was present in most strains, with a G + C content ranging from 14.7 to 30.8 mol % G + C. Heterogeneity in microscopic and colonial characteristics was not reflected in differences in the mean G + C content of the chromosomal DNAs. Strains varied in the G + C contents of satelite DNA, but these did not correlate with traditional species concepts.

Arthrodermataceae↗
PubMed1980

The preparation and partial characterization of antigenic fractions obtained from the mycelial walls of several Aspergillus species.

Extracts with immunological activity were prepared from Aspergillus fumigatus, A. flavus, A. terreus, A. niger and A. nidulans. In each case crude mycelial wall was extracted with an aqueous solution of Triton X-100 giving detergent-soluble material. Further fractionation was achieved by removing the detergent from this solution; the resultant precipitate was removed by centrifugation, and the aqueous supernatant was used as a source of soluble antigens. The sensitivity of these preparations was compared with that of water-soluble antigenic material, prepared from whole macerated mycelium, by double diffusion and counterimmunoelectrophoresis using homologous antisera and sera from patients suffering from aspergilloma and allergic bronchopulmonary aspergillosis. The selectivity of these antigenic preparations was monitored with heterologous antisera raised in rabbits. Batch variability was analysed for one strain of A. fumigatus using chemical and immunological methods. The nature of the antigenic sites involved in these reactions was investigated by studying the susceptibility of the preparations to proteolytic hydrolysis, periodate oxidation and concanavalin A treatment. The total protein and carbohydrate content of each fraction was determined and the constituent sugars analysed in an attempt to correlate chemical composition with antigenic activity.

Antigens, Fungal↗
PubMed1980

Preparation of Aspergillus fumigatus antigens and their analysis by two-dimensional immunoelectrophoresis.

The water-soluble components of Aspergillus fumigatus mycelium were partially separated by fractional precipitation with ammonium sulphate. The total protein and neutral-sugar content were determined for each of the four fractions prepared and their immunological activity was examined by double diffusion. Partial chemical characterisation of these isolates by polyacrylamide-gel electrophoresis was linked to their precipitability by allowing the separated components to diffuse from the gel into an agarose medium containing an appropriate antiserum. The distribution and reactivity of antigens was monitored by two-dimensional immunoelectrophoresis with rabbit sera raised against either mycelial or culture-filtrate antigens and human sera, obtained from patients with aspergilloma and from patients with allergic bronchopulmonary aspergillosis. This technique was also used to establish that considerable variation exists in the precipitation profile seen among patient specimens. Several antigens were found to possess sugar residues that interacted with concanavalin A, when this lectin was used in an intermediate gel in two-dimensional immunoelectrophoresis.

Animals↗