Biomedical subjects

Michael S Waugh

Publications and source records attributed to Michael S Waugh.

3 recordsLinked to original sources

PubMed2007

Silent corticotroph cell pituitary adenoma in a struma ovarii.

This is the first report of a silent corticotroph cell pituitary adenoma arising in a struma ovarii. The patient, a 79-year-old woman, was found to have an asymptomatic left-sided adnexal mass confirmed by vaginal sonography to be a complex cystic and solid tumor. Pathological analysis demonstrated an 8-cm partially cystic struma ovarii in which there was a focus of predominantly basophilic adenohypophyseal cells arranged in a diffuse pattern, adjacent to mature neural tissue containing numerous Herring bodies. The epithelial lining cells of the colloid-filled small and cystic follicles were immunoreactive for thyroglobulin. The pituitary cells were predominantly immunoreactive for adrenocorticotropic hormone, in addition to synaptophysin.

ACTH-Secreting Pituitary Adenoma↗

PubMed2003

Ras1 controls pheromone expression and response during mating in Cryptococcus neoformans.

The Cryptococcus neoformans Ras1 signal transduction pathway controls mating, hyphal differentiation, and the ability of this opportunistic human fungal pathogen to grow at elevated temperatures. To further elucidate how Ras1 signals in this organism, the RAS1 gene was disrupted in the congenic serotype D strain background. Genetic epistasis experiments indicated that Ras1 regulates the mating response through the MAP kinase/pheromone response pathway. In fact, Ras1 is required for the transcriptional induction of elements of the pheromone response pathway. However, the ability of C. neoformans Ras1 to allow growth at 37 degrees C is mediated by a separate signaling pathway. Therefore a single Ras protein may differentially activate distinct downstream targets in response to different signals within the same organism. This conserved signaling motif has been coopted in C. neoformans to regulate mating and morphogenesis in addition to being required for its pathogenic potential.

Crosses, Genetic↗

PubMed2002

Ras1 and Ras2 contribute shared and unique roles in physiology and virulence of Cryptococcus neoformans.

The Ras1 signal transduction pathway controls the ability of the pathogenic fungus Cryptococcus neoformans to grow at high temperatures and to mate. A second RAS gene was identified in this organism. RAS2 is expressed at a very low level compared to RAS1, and a ras2 mutation caused no alterations in vegetative growth rate, differentiation or virulence factor expression. The ras2 mutant strain was equally virulent to the wild-type strain in the murine inhalational model of cryptococcosis. Although a ras1 ras2 double mutant strain is viable, mutation of both RAS genes results in a decreased growth rate at all temperatures compared to strains with either single mutation. Overexpression of the RAS2 gene completely suppressed the ras1 mutant mating defect and partially suppressed its high temperature growth defect. After prolonged incubation at a restrictive temperature, the ras1 mutant demonstrated actin polarity defects that were also partially suppressed by RAS2 overexpression. These studies indicate that the C. neoformans Ras1 and Ras2 proteins share overlapping functions, but also play distinct signalling roles. Our findings also suggest a mechanism by which Ras1 controls growth of this pathogenic fungus at 37 degrees C, supporting a conserved role for Ras homologues in microbial cellular differentiation, morphogenesis and virulence.

Actins↗