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Biomedical subjects

G S Bulmer

Publications and source records attributed to G S Bulmer.

11 recordsLinked to original sources
PubMed1979

Fatal Beauveria bassiana infection in a captive American alligator.

The entomopathogenic fungus, Beauveria bassiana, was isolated from pulmonary lesions of a dead American alligator (Alligator mississipiensis) at the Oklahoma City Zoo. Colonies of the fungus, which had sporulated in vivo, were found in the thoracic air spaces. Septate, branching hyphae and fungal spores were seen in stained histologic sections of pleura and lung. Dissemination to other viscera had not occurred. This case indicated that B bassiana, a rare vertebrate pathogen, may be a fatal mycotic agent in captive reptiles.

Alligators and Crocodiles↗
PubMed1979

Immunization of mice with an avirulent pseudohyphal form of Cryptococcus neoformans.

Mice were immunized with a viable, avirulent strain of Cryptococcus neoformans. Lymphocyte blastogenic assays showed a 10-fold increase in reactivity of sensitized spleen cells, and histopathologic examination revealed marked splenic hyperplasia. Thirty-two days after intravenous inoculation with a virulent strain of C. neoformans, none of the control animals survived whereas 60 percent of the immunized mice were alive with no clinical evidence of disease. This animal model shows that protective immunity can be established, and once developed, provide a better model for the study of important aspects of immunity in fungal disease.

Animals↗
PubMed1979

Cryptococcus neoformans: gastronomic delight of a soil ameba.

During 7 days of incubation in vitro the trophozoite stage of the free-living soil amoeba, Acanthamoeba polyphaga, phagocytized and killed 78-97% of the cells of three strains of Cryptococcus neoformans. With one strain, incubation time was increased to nine days and 99% of the yeast cells were killed. It was calculated that during 4-9 days of incubation a single trophozoite phagocytized and killed a daily average of 84 yeast cells. The lethal effect of A. polyphaga on C. neoformans may represent a biological control mechanism in nature. Some of the surviving cells of C. neoformans developed into colonies containing pseudohyphae; these pseudolhyphal forms may be a biological 'escape hatch'.

Amoeba↗
PubMed1979

Phagocytosis and intracellular fate of Sporothrix schenckii.

Human polymorphonuclear leukocytes (PMNLs) phagocytized and killed yeast-phase cells of Sporothrix schenckii in vitro in the presence of 10% unheated serum. The combination of H2O2, KI, and human PMNL myeloperoxidase was lethal to yeast-phase S. schenckii. The results of this investigation suggest that PMNLs may play an important role in host resistance to infection with S. schenckii.

Candida albicans↗
PubMed1979

Kinetics of lymphocyte transformation in mice immunized with viable avirulent forms of Cryptococcus neoformans.

A murine model was developed to study the cell-mediated immune response of mice immunized with one of two live, avirulent forms of Cryptococcus neoformans: a nonencapsulated mutant and a thinly encapsulated pseudohyphal variant. A lymphocyte transformation assay was used to evaluate the cellular response of control and sensitized spleen cells after in vitro incubation with three merthiolate-killed whole-cell antigens of C. neoformans. An antigen-to-spleen cell ratio of 10:1 and 5 days of incubation of antigen-spleen cell mixtures were established as optimal conditions for maximum lymphocyte transformation. Maximum responses occurred from 2 to 3 weeks after the last of eight weekly intraperitoneal inoculations of C. neoformans. This assay provided an accurate, reproducible method of studying cell-mediated immunity to C. neoformans, and applications to the study of cryptococcal pathogenesis are proposed.

Animals↗
PubMed1979

Fatal mycotic pulmonary disease of captive American alligators.

Fatal pulmonary disease occurred in two captive American alligators. The entomopathogenic fungus, Beauveria bassiana, was isolated from pulmonary lesions in both alligators. An extended hibernation period because of a severe winter and a failure of the zoo heating system may have predisposed the alligators to infection.

Alligators and Crocodiles↗
PubMed1978

Cryptococcus neoformans: pseudohyphal forms surviving culture with Acanthamoeba polyphaga.

During experiments on the gastrointestinal tract as a possible portal of entry for Cryptococcus neoformans, we occasionally observed the free-living amoeba, Acanthamoeba polyphaga, growing in the presence of C. neoformans cultured from mouse feces. Examination of the amoebic trophozoites revealed that they were engorged with yeast cells. Over a period of 2 to 3 weeks of incubation, the amoebae apparently killed most of the yeast cells. Some of the surviving C. neoformans cells formed atypical colonies which contained pseudohyphae. Seven other strains have since been cultured with this amoeba. Pseudohyphal forms were found among the surviving colonies in all strains tested. Virulence studies were performed on one randomly selected pseudohyphal isolate from each of the eight strains of C. neoformans. Pseudohyphal isolates from seven of the eight strains failed to kill mice 30 days after intracranial inoculation. The potential role of soil amoebae in the control of C. neoformans in nature is discussed.

Amoeba↗
PubMed1977

Cryptococcus neoformans: size range of infectious particles from aerosolized soil.

Although cryptococcosis is characterized as a chronic central nervous system disease, it is generally accepted that the lungs are the primary portal of entry for the etiological agent. Despite this, there is a distinct lack of evidence that viable airborne particles of Cryptococcus neoformans are small enough to reach the alveoli. Two encapsulated strains and one nonencapsulated strain of C. neoformans were inoculated into 250-g quantities of sterile soil. Throughout the 0 to 12 weeks of incubation, this soil was aerosolized in a sealed chamber with a Waring blender. Samples of the resultant dust cloud were taken with an Anderson air sampler from which the numbers and sizes of viable airborne particles were determined. Of the viable organisms aspirated into the air sampler, 15% were 0.65 to 2 micron in diameter. As incubation time in soil increased, the size of the particles decreased, and increased numbers of C. neoformans cells 0.65 to 2 micron in diameter were isolated. The presence of viable cells less than 2 micron in soil aerosols indicated that, under certain conditions in nature, C. neoformans cells exist in sizes that are capable of deep lung deposition.

Aerosols↗
PubMed1975

Phagocytosis of Cryptococcus neoformans by alveolar macrophages.

Guinea pig pulmonary macrophages phagocytized but did not kill nonencapsulated cells of Cryptococcus neoformans. The phagocytic process was inhibited by cryptococcal capsular polysaccharide. Pulmonary macrophages, activated by preinjecting heat-killed bacteria into intact animals, did not kill the engulfed yeast cells. Labeled cells of C. neoformans were neither killed nor cleared from guinea pig lungs 6 h postexposure. The results of our experiments indicate that during the first few hours after the lung is exposed to the infectious particle of C. neoformans the pulmonary macrophage does not function primarily to kill engulfed yeast cells. We believe that a rapid yet transient acute inflammatory response probably plays a major role in this process during the first few hours after C. neoformans enters the lung.

Acid Phosphatase↗