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Biomedical subjects

R J Hay

Publications and source records attributed to R J Hay.

At least 181 records · Page 10Linked to original sources
PubMed1988

Experimental dermatophytosis in mice: correlation between light and electron microscopic changes in primary, secondary and chronic infections.

The histopathological and electron microscopic features of experimental dermatophytosis due to Trichophyton quinckeanum in Balb/c mice have been studied in animals with primary, secondary and chronic infections. Infected animals all showed pathological changes with adherence of microconidia to keratinocytes within 4 h of infection. Other features were the early infiltration of neutrophils, the formation of a mycelial mass (scutulum) in the epidermis, and epidermal oedema. Increased thickness of the epidermis was measured within 3 days of infection, although this was mainly due to oedema. The main differences seen in secondary infections were the paucity of fungal elements, even after 24 h, a sustained increase in epidermal thickness, and the dense dermal infiltrate of mononuclear cells. Chronically infected animals showed similar changes to those at the peak of a primary infection, but in addition there were large numbers of mast cells in the dermis. Cells carrying Ia markers were identified in the epidermis (Langerhans cells) and the dermis (macrophages) in all infections and their distribution did not appear to change. Although recovery from infection has been correlated previously with T lymphocyte mediated responses an increase in the number of cell layers of the epidermis and a dense infiltrate of neutrophils at the zone of infection were both seen within 2 days of infection. It is suggested that neutrophil killing of fungi and increased epidermal proliferation, not dependent on T cell activation, may also be implicated in host defence against dermatophytes.

Animals↗
PubMed1987

Leucocyte chemotaxis to mycetoma agents--the effect of the antifungal drugs griseofulvin and ketoconazole.

Polymorphonuclear leucocytes are the predominant cell type in the inflammatory infiltrate around mycetoma grains. Human leucocyte chemotaxis using cells from healthy subjects has been demonstrated using cytoplasmic antigens from 3 mycetoma agents: Madurella mycetomatis and Pseudallescheria boydii, both fungi, and Streptomyces somaliensis, an actinomycete. There was a statistically insignificant increase in chemotaxis in the presence of ketoconazole, but griseofulvin was a potent inhibitor of leucocyte movement. Griseofulvin has been used to improve the clinical appearances in eumycetoma (fungal mycetoma) cases which respond poorly to antifungal chemotherapy and it is suggested that its effect in this condition depends, in part, on its ability to inhibit leucocyte aggregation around mycetoma grains.

Antigens, Fungal↗
PubMed1987

Paracoccidioidin sensitization in Guyana--a preliminary skin test survey in hospitalized patients and laboratory workers.

Thirty-one percent of a group of 49 hospitalized patients or laboratory workers in Guyana showed positive intradermal paracoccidioidin tests in the presence of negative histoplasmin reactions. In 2 patients (4%), the intradermal reactions to paracoccidioidin were greater than 10 mm in diameter. The prevalence of positive reactors in a selected population suggests that paracoccidioidomycosis may be endemic in Guyana although no clinical case has been reported from the country. A further survey in a larger, unselected population would lead to a clearer understanding of the problem.

Adolescent↗
PubMed1987

WiDr is a derivative of another colon adenocarcinoma cell line, HT-29.

This paper documents chromosomal and isozymic evidence indicating that WiDr is a derivative of another colon adenocarcinoma cell line, HT-29, which was established in 1964. The phenotypes for seven isozymes studied were identical for all HT-29 and WiDr cell lines. The karyotypes were similar between four HT-29 cultures separated by more than 100 passages and two WiDr cultures that were studied independently in 1979 and 1985. The isozymic and karyotypic data are consistent with that described for the cell line WiDr, originally reported in 1979. Detailed karyotypic comparisons further show that cultures of WiDr possess all nine chromosomal markers found in the initial HT-29 (passage 19) cultures. However, both the higher passaged HT-29 and WiDr differ from the initial HT-29 (passage 19) because it has an additional five to eight constitutive marker chromosomes. An increase or decrease of one copy in several normal chromosomes is also noticed with more normal chromosome gains than losses. The study provides another example demonstrating the remarkable karyotypic stability within a heteroploid cell line with continued passage. It also reemphasizes the critical need for detailed karyotypic and isoenzymic studies on all cell lines in common use.

Adenocarcinoma↗
PubMed1987

Ultrastructural and immunogenic changes in the formation of mycetoma grains.

The differences in the fine structure and antigenic determinants of mycetoma fungi in the mycelial phase in vitro and in grains in vivo facilitate an interpretation of grain formation. Aggregates of hyphal elements with multiple and thickened walls was a feature of the fungi in vivo. Associated with hyphal wall material, numerous polysaccharide microfibrils were detected in grains of Madurella mycetomatis. These were not seen associated with hyphal elements in vitro and it is suggested that these structures may be concerned with the aggregation of fungal elements in the formation of grains. Antibodies directed against the fungi in vitro were shown, by indirect immunogold labelling, to bind at identical sites in fungal material grown in vitro as in mycetoma grains. However the grain matrix was not labelled, suggesting that part of the structure formed in vivo is composed of modified antigen or is host derived.

Antigens, Fungal↗
PubMed1987

Circulating antigens and antibodies in human and mouse dermatophytosis: use of monoclonal antibody reactive to phosphorylcholine-like epitopes.

The presence of circulating antibodies in the sera of patients infected with either Trichophyton concentricum or Trichophyton rubrum, and in the sera of BALB/c mice chronically infected with Trichophyton quinckeanum, was determined by ELISA. High levels of antibody to dermatophyte cytoplasmic antigens were detected both in infected humans and in mice. Partial inhibition of this reaction was observed by pretreatment of the sera with the hapten phosphorylcholine (PC). Moreover, antibodies were shown to have some reactivity with PC when tested by ELISA against PC conjugated to bovine serum albumin. Significant levels of circulating antigen were detected in patients with T. concentricum and T. rubrum infections, but not in uninfected subjects, by an immunoradiometric assay using a monoclonal antibody, Tq-1, which reacts with the PC-like epitopes of dermatophytes. It is possible that this dermatophyte antigen may play a role in modulating the cell-mediated immune responses, which would appear to be defective in most patients with these chronic forms of dermatophytosis.

Animals↗
PubMed1987

Adherence of dermatophyte microconidia and arthroconidia to human keratinocytes in vitro.

The early interaction, adherence, between dermatophyte conidia and human keratinocytes has been studied in vitro. Two spore forms were used: microconidia and arthroconidia produced in vitro. The adherence of spores from three dermatophyte species, Trichophyton rubrum, T interdigitale, and T quinckeanum, was investigated using keratinocyte suspensions from different skin sites. Time-dependent adherence was demonstrated for all fungi studied with maximum adherence occurring between 3 and 4 h. There were no significant differences in adherence rates between the organisms studied. An order of affinity was established between keratinocytes from different sites and significant differences were demonstrated in adherence of microconidia to skin cells derived from sole versus knee. No differences in adherence rates were demonstrated in atopics versus patients with chronic dermatophytosis and normals. Adherence was inhibited, but not abolished, by subinhibitory concentrations of ketoconazole, itraconazole, and griseofulvin. The interaction between microconidia, arthroconidia, and keratinocytes was verified with scanning and transmission electron microscopy.

Antifungal Agents↗
PubMed1987

The ultrastructure of actinomycetoma grains caused by Streptomyces somaliensis.

This study compares the in vitro ultrastructure of Streptomyces somaliensis with the grain formation seen in vivo. Cultured forms were cocco-bacillary with thick cell walls and septa. Individual cells stained with PAS.TCH and Alcian blue. Grains were largely composed of an electron-dense fibrillar matrix surrounding clear areas, some of which contained organisms. The ultrastructural appearances of the latter were not significantly different from those seen in vitro although the cell wall was less well defined and did not stain with Alcian blue, and there were more intracellular lipid droplets. Host cells surrounding the mass were incorporated into the structure of the grain, a process associated with cell death. The grains of S. somaliensis appear to be derived from both host and actinomycete elements. Compared to other mycetoma agents the mechanism of grain formation by this organism is distinctive.

Cell Wall↗