PubMed Health⌕ Search

Biomedical subjects

D W Mackenzie

Publications and source records attributed to D W Mackenzie.

At least 19 recordsLinked to original sources
PubMed1994

Gelatinase activity of exoantigens from virulent and non-virulent isolates of Paracoccidioides brasiliensis.

Differences in the occurrence of components with gelatinase activity were detected among four isolates of Paracoccidioides brasiliensis: Pb339 and Pb18 (highly virulent), and Pb265 and Pb18AV (very low virulence). Culture filtrates from these isolates were electrophoresed in substrate gels and tested for gelatinase activity. Pb339 showed three enzyme bands of apparent molecular masses: 43, 53 and 78 kDa; Pb18 had two bands, one at 59 kDa and another with molecular mass higher than 78 kDa. Isolate Pb18AV showed only one band at 78 kDa and Pb265 exhibited a component of molecular mass which failed to enter the separating gel.

Antigens, Fungal↗
PubMed1994

Simplified adsorption method for detection of antibodies to Candida albicans germ tubes.

Two modifications that simplify and shorten a method for adsorption of the antibodies against the antigens expressed on both blastospore and germ tube cell wall surfaces (methods 2 and 3) were compared with the original method of adsorption (method 1) to detect anti-Candida albicans germ tube antibodies in 154 serum specimens. Adsorption of the sera by both modified methods resulted in titers very similar to those obtained by the original method. Only 5.2% of serum specimens tested by method 2 and 5.8% of serum specimens tested by method 3 presented greater than one dilution discrepancies in the titers with respect to the titer observed by method 1. When a test based on method 2 was evaluated with sera from patients with invasive candidiasis, the best discriminatory results (sensitivity, 84.6%; specificity, 87.9%; positive predictive value, 75.9%; negative predictive value, 92.7%; efficiency, 86.9%) were obtained when a titer of > or = 1:160 was considered positive.

Antibodies, Fungal↗
PubMed1993

Increasing incidence of cryptococcosis in the United Kingdom.

The incidence of infection with Cryptococcus neoformans in the United Kingdom during the years between 1953 and 1981 is compared with that between 1982 and 1991. The patients were those from whom samples were submitted to the PHLS Mycological Reference Laboratory (MRL), or those in whom the disease was confirmed elsewhere in the United Kingdom and reported to PHLS Communicable Disease Surveillance Centre (CDSC). In all, 83 cases were identified between 1953 and 1981 and 322 between 1982 and 1991, 201 of which were known to be HIV-associated. The incidence of infection with Cryptococcus neoformans has increased four-fold in the last decade. It is an increasing cause of infection in immunosuppressed patients, most notably those with HIV infection. Currently, 4.0% patients with AIDS in the United Kingdom are known to have developed cryptococcosis.

Acquired Immunodeficiency Syndrome↗
PubMed1993

[Usefulness of serology in the diagnosis of Candida tropicalis septicemia].

In this study, we have evaluated the usefulness of eight serologic tests in the diagnosis of a Candida tropicalis septicaemia in a patient with acute myeloid leukaemia. Among the tests used, detection of mannose and candida antigen in serum allowed a high degree of suspicion of infection, earlier than the isolation of this species on mycological cultures from blood or oesophagic samples. Detection of anti-C. albicans antibodies was useless but low titres of anti-C. tropicalis antibodies were observed. In spite of early diagnosis and antifungal treatment, the complication of the disseminated candidiasis with a Pseudomonas aeruginosa septicaemia, concluded with the patient's exitus.

Aged↗
PubMed1993

Qualitative and quantitative differences in recognition patterns of Candida albicans protein and polysaccharide antigens by human sera.

Cytoplasmic and cell wall proteins and glycoproteins extracted from Candida albicans germ tubes were screened by Western blotting for their ability to differentiate between the serological responses of patients with candidosis and healthy individuals. Molecules of 114, 74 and 65 kDa were not recognized by any sera. Qualitative differences were observed for responses to proteins and glycoproteins from 29 to 60 kDa. Conversely, only quantitative differences were found to high molecular mass glycoproteins. Their recognition by control sera was invariably associated with reactivity against a 14-18 kDa antigen. However, despite a high level of antibodies against high molecular mass mannoproteins, some patients sera failed to react with the 14-18 kDa antigen, or lost this reactivity during the course of the disease.

Adult↗
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↗