Biomedical subjects

R D Diamond

Publications and source records attributed to R D Diamond.

75 records · Page 5Linked to original sources

PubMedDate not supplied

Fungal surfaces: effects of interactions with phagocytic cells.

Fungal surfaces undergo profound changes during morphogenesis that modify host responses. For example, inhaled spores or conidia of Rhizopus or Aspergillus lose their surface hydrophobic outer layers, initially swell, and then germinate to form mycelia that may invade tissues. These various fungal forms not only elicit differing response from host phagocytic cells but also differ in their susceptibilities to cellular microbicidal mechanisms. In addition, studies comparing neutrophil activation responses to opsonized and unopsonized Candida hyphae indicate that the presence or absence of antibody or complement on fungal surfaces determines distinct patterns of the early responses of neutrophils to stimulation, such as membrane depolarization, cytosolic increase in calcium, and phosphoinositide turnover. These initial events in the neutrophil activation sequence are followed by release of both fungicidal granule constituents and oxidants from the respiratory burst. The quantity and specificity of delivery of these toxic neutrophil products ultimately determine the relative efficiency of fungicidal activity versus inflammatory cytotoxicity to host cells.

Cell Wall↗

PubMedDate not supplied

Immune response to fungal infection.

In general, fungi are saprophytes that are well adapted to grow in nature supported by diverse nutritional substrates. For fungi, in contrast to many other microorganisms that infect humans, parasitism is an accidental phenomenon rather than an obligatory requirement for survival. Thus, with progressive improvement in our capabilities to prolong survival of patients with global defects in host defense mechanisms, clinical experience suggests that human tissues may support growth of numerous species of saprophytic fungi that share the capacity to grow at 37 degrees C. Normally, however, a broad array of natural and acquired host defense mechanisms make the occurrence of progressive, systemic, life-threatening mycoses extremely rare events. When one or another of these host defense mechanisms is compromised, one of a variety of significant fungal infections may then progress. Mycoses may be broadly categorized into those controlled largely by natural cellular defenses vs. acquired cell-mediated immunity. Notwithstanding data that permit such general classification of host factors controlling one or another invasive mycosis, the diverse structural and antigenic properties of individual fungi create unique patterns of infections in individual, characteristic host settings. Thus, while some broad generalizations are possible, definition of predisposing factors for specific individual mycoses (and, ultimately, prospects for corrective immunotherapy) requires careful characterization of diverse features of fungal forms mediating divergent immune responses.

Animals↗

PubMedDate not supplied

The growing problem of mycoses in patients infected with the human immunodeficiency virus.

With the rapid increase in cases of AIDS over the past 10 years, certain mycoses have dramatically risen in frequency, particularly those contained by T cell-mediated mechanisms of host defense. In this clinical setting mucocutaneous candidiasis as well as systemic cryptococcosis, histoplasmosis, and coccidioidomycosis pose special diagnostic and/or therapeutic challenges. Compared with fungal infections in general, AIDS-associated mycoses are more likely to have nonspecific clinical manifestations; moreover, treatments effective in other settings seldom are curative. These problems have led to new vigilance regarding mycoses in the differential diagnosis of complications of infection due to the human immunodeficiency virus (HIV) and have necessitated a redefinition of goals: the aim is now to suppress rather than cure infection in most cases. This change has stimulated trials of new antifungal agents and regimens particularly designed to facilitate long-term outpatient management of mycoses without interfering with treatment of either HIV infection itself or other concomitant complications.

Acquired Immunodeficiency Syndrome↗