Biomedical subjects

M J McCullough

Publications and source records attributed to M J McCullough.

29 records · Page 2Linked to original sources

PubMed1998

Species identification and virulence attributes of Saccharomyces boulardii (nom. inval.).

Saccharomyces boulardii (nom. inval.) has been used for the treatment of several types of diarrhea. Recent studies have confirmed that S. boulardii is effective in the treatment of diarrhea, in particular chronic or recurrent diarrhea, and furthermore that it is a safe and well-tolerated treatment. The aim of the present study was to identify strains of S. boulardii to the species level and assess their virulence in established murine models. Three strains of S. boulardii were obtained from commercially available products in France and Italy. The three S. boulardii strains did not form spores upon repeated testing. Therefore, classical methods used for the identification of Saccharomyces spp. could not be undertaken. Typing by using the restriction fragment length polymorphisms (RFLPs) of the PCR-amplified intergenic transcribed spacer regions (including the 5. 8S ribosomal DNA) showed that the three isolates of S. boulardii were not separable from authentic isolates of Saccharomyces cerevisiae with any of the 10 restriction endonucleases assessed, whereas 9 of the 10 recognized species of Saccharomyces could be differentiated. RFLP analysis of cellular DNA with EcoRI showed that all three strains of S. boulardii had identical patterns and were similar to other authentic S. cerevisiae isolates tested. Therefore, the commercial strains of S. boulardii available to us cannot be genotypically distinguished from S. cerevisiae. Two S. boulardii strains were tested in CD-1 and DBA/2N mouse models of systemic disease and showed intermediate virulence compared with virulent and avirulent strains of S. cerevisiae. The results of the present study show that these S. boulardii strains are asporogenous strains of the species S. cerevisiae, not representatives of a distinct and separate species, and possess moderate virulence in murine models of systemic infection. Therefore, caution should be advised in the clinical use of these strains in immunocompromised patients until further study is undertaken.

Animals↗

PubMed1998

Epidemiology of Candida albicans isolates from heroin addicts analysed by DNA typing.

Candida albicans is a ubiquitous commensal organism of humans. Several studies have examined outbreaks of candidiasis in heroin addicts utilizing a variety of methods to assess the epidemiological relatedness of the isolates and suggested the association of certain subtypes with disease in this patient population. The aim of the present study was to assess a separate group of isolates of C. albicans from heroin addicts in Spain using a DNA typing method. Results showed that, of the 34 isolates from heroin addicts, 20 were in subgroup IA, 10 were in subgroup IB and no isolates were of the subtype IA2. In addition, four isolates were in a recently described subgroup IC. Control isolates from the same geographical region (Spain) showed a distribution similar to the Spanish heroin addict isolates (12 subgroup IA, three subgroup IB, two subgroup IC and no isolates of the subtype IA2). In this study isolates from the same locality appeared similar irrespective of the patient population from which they were isolated. These results indicated that there may be differing geographical diversity of C. albicans than has previously been reported and that the newly described genotypic subgroup (IC) of C. albicans may be more widespread than previously shown.

Abscess↗

PubMed1997

Human immunodeficiency virus infection: a review of the mode of infection, pathogenesis, disease course, and the general and clinical manifestations.

Acquired immunodeficiency syndrome (AIDS) was first recognized in 1981 and in 1983 the virus responsible for this syndrome, the human immunodeficiency virus, was first isolated. There has been an increasing understanding of the many aspects related to infection with this virus and this review discusses the historical as well as the more recent findings related to infection with this virus. In particular, the pathogenesis, mode and course of infection are discussed followed by an overview of the general and oral manifestations of infection with this virus.

AIDS-Related Opportunistic Infections↗

PubMed1997

Application of DNA typing methods and genetic analysis to epidemiology and taxonomy of Saccharomyces isolates.

We have previously described differences in phenotype and virulence among clinical and nonclinical isolates of Saccharomyces. To further characterize these isolates, a comparison of restriction fragment length polymorphism (RFLP) patterns and genetic analysis were done. The cellular DNA of each of 49 clinical and 11 nonclinical isolates of Saccharomyces was digested with the endonuclease EcoRI, and the resultant fragments were separated by electrophoresis. Sixty isolates were grouped on the basis of the presence (group B) or absence (group A) of a 3-kb band. Group A contained 43 isolates (35 clinical and 8 nonclinical isolates) in 31 discernible subgroups, and group B had 17 isolates (14 clinical and 3 nonclinical isolates) in 10 subgroups. Interestingly, six of eight known vaginal isolates were group B, with four of those six being identical. Virulence of isolates was associated with membership in group A (P = 0.03). Comparison of known members of sibling species within the genus Saccharomyces, which cannot be distinguished by standard biochemical tests, showed that S. paradoxus, S. bayanus, and S. cerevisiae could be differentiated by RFLP analysis. Genetic analysis of the isolates forming viable spores showed that most group A isolates were diploid and members of the species S. cerevisiae. Those group A and B isolates unable to form viable spores may be diploid hybrids between Saccharomyces species. The group B isolates that formed viable spores were tetraploid and may also be interspecific hybrids. Overall, clinical isolates of Saccharomyces were very heterogeneous and exhibited little clonality. RFLP pattern analysis could be a useful method of demonstrating transmission in patients with infection or between environmental sources and patients.

DNA, Fungal↗

PubMed1996

Candida albicans: a review of its history, taxonomy, epidemiology, virulence attributes, and methods of strain differentiation.

The dimorphic yeast Candida albicans has been recognized as an increasingly important human pathogen particularly in immunocompromised hosts because of advanced age, infection or immunosuppressive therapy. This review outlines the history, taxonomy and epidemiology of this medically important yeast as well as discussing some of characteristics which are purported to be related to its virulence. Methods utilized for strain differentiation in the study of the epidemiologic relationship of members of this species are discussed.

Candida albicans↗

PubMed1994

Genotype and phenotype of oral Candida albicans from patients infected with the human immunodeficiency virus.

Candida albicans has been shown to vary in its phenotypic expression with the progression of human immunodeficiency virus (HIV) infection. Isolates of C. albicans were obtained from 45 patients with HIV infection during the progression of their disease and differentiated using two methods. The first utilized the morphological characteristics of colonies, and the second method utilized a small portion of C. albicans DNA as a probe on Southern-transferred, EcoRI-digested C. albicans genomic DNA. In 67% of the patients a single strain of C. albicans, as determined by the DNA analysis, was isolated from each individual. The phenotypic expression of the genetically identical strains varied considerably over the experimental period with one morphotype being predominant. These results showed that the genotype of C. albicans persisted in the majority of HIV-infected individuals, but that the phenotypical expression of this strain changed. A novel finding in this study was that 18 strains of C. albicans had DNA which did not hybridize to the probe used.

Candida albicans↗

PubMed1992

Involucrin expression in some oral lichenoid lesions.

The aim of this investigation was to assess the reproducibility of a study which reported that involucrin could be used as a diagnostic marker in oral lichenoid lesions. Twenty-eight formalin-fixed, paraffin-embedded specimens were examined. They included tissue from 13 patients with lichen planus, 11 with drug-related lichenoid reactions, one with dysplasia in a lichenoid lesion and three with normal oral mucosa. In each case the biopsy site was the buccal mucosa, PAS stained smears for fungi were negative and immunofluorescence results supported the diagnosis. An immunoperoxidase technique was used to demonstrate involucrin reactivity. In all sections there was consistent positive staining for involucrin in the superficial layers of the epithelium and all the basal layers were negative. In conclusion there were no demonstrable differences in the involucrin reactivity between the different lesions.

Epithelium↗

PubMed1992

Quantitation and morphotyping of Candida albicans from healthy mouths and from mouths affected by erythematous candidosis.

Imprint culture and a mouthwash method were used to determine if quantitative differences exist between isolates of Candida albicans from individuals with healthy oral mucosa and from patients with erythematous candidosis (EC). The C. albicans isolated were differentiated by morphotyping. No quantitative difference in yeast isolations was observed with either technique irrespective of tobacco smoking status, the presence of a prosthesis, or EC. Multiple morphotypes were isolated from smokers with upper dentures and from smokers and non-smokers with EC, whilst a single morphotype was isolated from non-smokers with a healthy oral mucosa.

Adult↗

PubMed1985

CT collimator damage: detection by testing scan beam and laser-light alignment.

A test for CT scanner laser-light alignment is described. Ready-pack film is taped around a cylindrical phantom, and laser-light position relative to x-ray beam track is indicated by an arrangement of pin pricks through the film jacket. Performance of this test after x-ray tube replacement showed a band of stray radiation running parallel to the scan beam. The errant beam was caused by a failure to interlock the prepatient collimator and scatter shield correctly.

Lasers↗

PubMed1977

Production of thermophilic actinomycete-hay aerosols for use in experimental hypersensitivity pneumonitis.

An investigation of the factors that influence the production of dense aerosols of Micropolyspora faeni and Thermoactinomyces vulgaris from hay cultures revealed that the density, freshness, and moisture content of the hay were important influences. Dry aerosols were produced under optimum conditions from hay cultures of either actinomycete and from sterile hay for inhalation challenges to unimmunized rabbits. Depressions in arterial oxygen tensions and hemolytic complement were monitored after such challenge. This investigation showed that hay cultures are capable of inciting a hypersensitivity-like reaction in the lungs, even in the absence of immunization to the organisms contained within the hay, but the entire hypersensitivity reaction cannot be attributed to M. faeni and T. vulgaris alone. Hay itself or other microbial or chemical components appear to have some heat-stable component that possibly contributes to the pathogenesis of the disease.

Aerosols↗

PubMedDate not supplied

Genetic differentiation of Candida albicans strains by mixed-linker polymerase chain reaction.

Restriction fragment length polymorphisms (RFLPs) of C. albicans were visualized using a mixed-linker polymerase chain reaction (PCR) and a C. albicans-specific primer (C. albicans 1059-bp species-specific repeat sequence). The method produced 10-14 bands of between 200 and 1400 bp on agarose gel electrophoresis and ethidium bromide staining. It gave comparable results to Southern blot hybridization with good reproducibility and the time required for the production of typing profiles was reduced to less than 2 days.

Base Sequence↗