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PubMed1977

The in vivo incorporation of [32P]-labeled orthophosphate into pyrophosphatidic acid and other phospholipids of Cryptococcus neoformans through cell growth.

Cryptococcus neoformans was cultured in a liquid medium containing [32P]-orthophosphate and harvested at various stages of cell growth. An aliquot of the [32P]-labeled cells was transferred to a nonradioactive medium, and the culture was continued again for some hours. The [32P]-radioactivity composition and the phosphorus composition of individual phospholipids relative to the total phospholipid through the incubation periods were estimated. Although levels of major phospholipids remained constant throughout the cell growth, the distribution pattern of the [32P]-radioactivity of individual phospholipids changed remarkably along with the progress of cell growth. The changing patterns of the specific radioactivities of individual phospholipids through the growth phase demonstrated that phosphatidic acid was one of the most active metabolites in phospholipids and that pyrophosphatidic acid was also metabolically active.

Cryptococcus↗
PubMed1991

Early events in initiation of alternative complement pathway activation by the capsule of Cryptococcus neoformans.

The capsule of Cryptococcus neoformans is a powerful activator of the alternative complement pathway. This study examined the manner in which the cryptococcal capsule influences initiation of and early events in complement activation by C. neoformans. These studies examined the effects of the classical and alternative pathways on the kinetics and early sites for deposition of C3 fragments on encapsulated cryptococci, nonencapsulated cryptococci, and zymosan. The results showed that nonencapsulated cryptococci and zymosan are qualitatively and quantitatively similar in the manner in which they initiate complement activation. Both utilize the classical and alternative pathways. Initiation via the classical pathway occurs suddenly and simultaneously at sites distributed over the entire cell surface. Initiation of the alternative pathway by zymosan and nonencapsulated cryptococci is characterized by a lag of 6 to 8 min before appreciable amounts of C3 accumulate on the cells. Alternative pathway initiation by zymosan and nonencapsulated cryptococci occurs at a limited number of focal initiation sites that expand with alternative pathway amplification to cover the cell surface. Presence of the cryptococcal capsule blocks classical pathway initiation, which would normally occur at the cryptococcal cell wall, and produces an initiation that is dependent solely on the alternative pathway. Initiation of the alternative pathway by the cryptococcal capsule is characterized by a lag in C3 accumulation and the appearance of a limited number of focal initiation sites which resemble those observed when the alternative pathway is activated by zymosan and nonencapsulated cryptococci.

Complement Activation↗
PubMed1975

Relationship between polyene resistance and sterol compositions in Cryptococcus neoformans.

Six mutants of Cryptococcus neoformans resistant to nystatin and pimaricin and three mutants resistant to amphotericin B were isolated by ultraviolet irradiation techniques from two wild-type strains. The major sterols of the wild-type strains were Delta(7)-ergosten-3beta-ol and ergosterol. All six mutants resistant to nystatin and pimaricin showed either loss of ergosterol and concurrent production of Delta(7, 22)-ergostadien-3beta-ol and Delta(7)-ergosten-3beta-ol, or loss of both the wild-type sterols, with production of Delta(8(9))-ergosten-3beta-ol and Delta(5, 8(9), 22)-ergostatrien-3beta-ol. The mutants producing Delta(7, 22)-ergostadien-3beta-ol and Delta(7)-ergosten-3beta-ol showed relatively low levels of resistance to nystatin and pimaricin, whereas the mutants producing Delta(8(9))-ergosten-3beta-ol and Delta(5, 8(0), 22)-ergostatrien-3beta-ol showed a high level of resistance to either drug. Although highly resistant to amphotericin B, however, the three mutants produced sterol compositions identical to those of the wild types, indicating that the strains acquired resistance other than by alteration of the membrane sterols. The mutants producing Delta(8(9)) and Delta(5, 8(9), 22) sterols were not virulent for mice, showed reduced growth rates at 25 C, and failed to grow at 37 C. The other mutants showed a slightly reduced rate of growth both at 25 and 37 C, and the virulence in mice was slightly reduced in comparison with that of the wild types. These comparisons were on gross observations and were not statistically analyzed.

Animals↗
PubMed1991

Catecholamine uptake, melanization, and oxygen toxicity in Cryptococcus neoformans.

Oxygen sensitivity mutations of Cryptococcus neoformans were mapped to three genetic loci. Three oxygen-sensitive mutants had mutations that appeared allelic and exhibited albinism tightly linked to oxygen sensitivity; these three and a fourth exhibited defects in catechol uptake and catechol oxidation to melanin. Catecholamine metabolism appears to protect C. neoformans from oxidants.

Biological Transport↗
PubMed1977

Cryptococcosis, with emphasis on the significance of isolation of Cryptococcus neoformans from the respiratory tract.

Cryptococcus neoformans was isolated from 65 patients: 11 had meningitis, 11 had disseminated cryptococcosis without meningitis, and 43 had C neoformans isolated from the respiratory tract. Predisposing conditions and the diagnostic value of cultures from various sites and of the latex agglutination test on cerebrospinal fluid and serum are analyzed for patients with extrapulmonary disease. Nine patients had pleural effusions; the effusion was cultured in six and yielded C neoformans in four. None of 11 deaths among 43 patients with respiratory tract isolates could be attributed to cryptococosis. The 32 survivors were nor treated with antifungal agents. Twenty-six of 43 patients with respiratory isolates had various bronchopulmonary disorders, with chronic obstructive pulmonary diseases and asthma the most common (28 percent). Seven of 28 patients (25 percent) with roentgenographically detected lung lesions had carcinoma of the lung. Roentgenographic evidence of a lung lesion and C neoformans grown from the respiratory tract warrant a further search for carcinoma of the lung.

Adult↗
PubMed1978

Delayed-type hypersensitivity responses in infected mice elicited by cytoplasmic fractions of Cryptococcus neoformans.

Four subcellular fractions of Cryptococcus neoformans prepared by differential centrifugation of disrupted whole yeast and a 3-day culture filtrate were examined for their ability to elicit delayed-type hypersensitivity in sensitized animals. The methods used to detect sensitization were (i) the footpad swelling test and inhibition of peritoneal macrophage migration in mice and (ii) skin testing in guinea pigs. Two entities, the post-mitochondrial supernatant and the culture filtrate, showed considerable activity in the footpad test, with 26- and 30-microliter 24-h swellings, respectively, at 6 weeks after infection. With the latter there was interference from a strong antibody-mediated 4-h skin reaction. The post-mitochondrial supernatant produced strong delayed-type hypersensitivity in guinea pigs at a dose of 69 microgram, and there was no demonstrable cross-reactivity in animals sensitized with heterologous fungi. The footpad swelling in mice correlated well with the macrophage migration inhibition test, with 71% inhibition in mice infected subcutaneously with C. neoformans at 6 weeks. However, mice infected intravenously developed poorer cell-mediated immunity than the subcutaneously infected mice. The post-mitochondrial supernatant was found to contain detectable amounts of cryptococcal capsular polysaccharide.

Animals↗
PubMed1975

Postitional specificity of fatty acids in pyrophosphatidic acid from Cryptococcus neoformans.

Pyrophosphatidic acid isolated from Cryptococcus neoformans was degraded to phosphatidic acid in aqueous pyridine. The phosphatidic acid was hydrolyzed by phospholipase A (EC 3.1.1.4) of Crotalus adamanteus to lysophosphatidic acid and 2-positioned fatty acids. From the analyses of the fatty acid composition of pyrophosphatidic acid and its degraded products (phosphatidid acid, lysophosphatidic acid, and fatty acid), it was concluded that most of the saturated fatty acids of pyrophosphatidic acid were at the 1,1'-positions while the unsaturated fatty acids were largely confined to the 2,2'-positions. The positional specificity of the fatty acids in pyrophosphatidic acid coincided with that of ordinary glycerophosphatides.

Chromatography↗
PubMed1992

Genetic association of mating types and virulence in Cryptococcus neoformans.

A pair of congenic Cryptococcus neoformans var. neoformans strains, B-4476 (a mating type) and B-4500 (alpha mating type), that presumably differ only in mating type was constructed. This pair and their progeny, five alpha type and five a type, were tested for virulence in mice. In the parent strains as well as the progeny, alpha type was clearly more virulent than a type. In addition, death tended to occur earlier among the alpha-strain-infected mice that died than among the mice that died by infection caused by a strains. These data strongly suggest the genetic association of virulence with mating type in this human fungal pathogen.

Animals↗
PubMed1978

Hypersensitivity pneumonitis with antibodies to Cryptococcus neoformans.

Clinical and immunological studies were made in forty-two patients diagnosed as suffering from hypersensitivity pneumonitis at Osaka Prefectural Habikino Hospital between 1973 and 1977. All the sera from forty-one patients tested had high titres of antibody against Cryptococcus neoformans in indirect fluorescent antibody tests, and twelve also had precepitins against Cryptococcus neoformans polysaccharide. Only about 10% of control sera from patients with other lung diseases had low titres of antibody against Cryptococcus neoformans. Antibody against Cryptococcus neoformans was also found frequently in the sera of asymptomatic members of the families of the patients. A possible relationship of Cryptococcus neoformans to hypersensitivity pneumonitis is suggested.

Adolescent↗
PubMed1992

[An urease negative Cryptococcus neoformans].

We report an urease negative Cryptococcus neoformans derived from pigeon dropping. This isolate produced brown pigmented colonies on cornmeal Tween-80 agar with 300 micrograms/ml caffeic acid, but was failure to hydrolyze urea. More identification tests were performed for this isolate, such as assimilation and fermentation of carbohydrates, nitrate assimilation, production of starch like compound, growth on GCP medium, germ tube formation and inoculation of mice, ect. Most of the results showed that the microbiological characteristics of the isolate were typical of C. neoformans except for negative urease test. Even though there has been a report about an urease negative C. neoformans derived from an AIDS patient, but we have never found any report about isolation from pigeon dropping or nature environment. We should pay attention to the exist of this atypical strain of C. neoformans in nature environment and the possibility of infection to human being. Additionally, we also be aware of the possibility of neglect when this urease negative C. neoformans is identified with urease test.

Animals↗
PubMed1992

Virulence, serotype, and molecular characteristics of environmental strains of Cryptococcus neoformans var. gattii.

Four strains of Cryptococcus neoformans var. gattii originating from Eucalyptus camaldulensis, three from Australia and one from San Francisco, were tested for their serotype, virulence for mice, and a number of genetic and molecular characteristics. All were found to be serotype B and showed significantly higher virulence for mice than did the type strains of C. neoformans var. gattii and Filobasidiella neoformans var. bacillispora, which were obtained from human cryptococcosis cases. Electrophoretic karyotypes of the strains from Australia were identical, although they were collected from sites at least 15 to 500 km apart. The electrophoretic karyotype of the strain from San Francisco was the same as that of the Australian isolates except for the mobility of one chromosome. On the contrary, no two isolates of serotype B (of a total of 11) from clinical sources were the same, regardless of their geographic origin. Furthermore, none of the clinical isolates showed a chromosomal banding pattern identical to that of Eucalyptus-originated strains. The Eucalyptus-originated strains failed to form dikaryons when crossed with the tester strains of the two varieties of F. neoformans. Hybridization analysis with a nucleic acid probe (AccuProbe C. neoformans Culture Confirmation Test; Gen-Probe Inc., San Diego, Calif.), however, showed signals of equal intensity for clinical strains and the Eucalyptus-originated strains. Various fungi phylogenetically related to C. neoformans, including a phenol oxidase-positive strain of Cryptococcus laurentii obtained from E. camaldulensis, were negative in the nucleic acid hybridization test. These observations confirm that, in spite of karyotypic differences and the lack of dikaryon formation with the tester strains of F. neoformans, Eucalyptus-originated C. neoformans var. gattii is the same organism as those isolated from cases of human infection. Furthermore, the C. neoformans culture confirmation test using a commercial nucleic acid probe is specific for C. neoformans.

Animals↗
PubMed1978

Carriage of Cryptococcus neoformans in the crops of pigeons.

Cryptococcus neoformans was found in the crops of four (1.3%) of 319 pigeons in the Charity Bird Hospital and the University Campus, Delhi. It was demonstrated repeatedly at the Bird Hospital in old pigeon excreta as well as in the air. The findings substantiate the current view that the pigeon itself is not a reservoir of C. neoformans although it may serve as a carrier of the fungus.

Air Microbiology↗
PubMedDate not supplied

Feline meningitis due to Cryptococcus neoformans var. neoformans and review of feline cryptococcosis.

Cryptococcus neoformans var. neoformans was ascertained as the prime cause of fatal meningitis in a young-adult female domestic cat who was suspected of rabies. The pathogen was isolated in heavy growth from the infected brain specimen on simplified sunflower seed (Helianthus annuus) medium at 30 degrees C. Periodic acid-Schiff stained impression smear revealed numerous cryptococcal cells. Histologically, pia-arachnoid showed thickening along with many circular yeast cells with and without budding morphologically consistent with Cr. neoformans. The detailed typing of the strain indicated that it belonged to serotype AD and Filobasidiella neoformans var. neoformans mating type 'alpha'. The emphasis is given on early diagnosis by immunological and mycological techniques and prompt chemotherapy to avert the fatal consequences of this enigmatic mycosis.

Animals↗
PubMed1992

The ecology of Cryptococcus neoformans.

Environmental isolations have established that Cryptococcus neoformans var. gattii serotype B appears to have a specific ecological association with Eucalyptus camaldulensis. The global distribution of the tree appears to correspond to the epidemiologic distribution of cryptococcosis caused by C. neoformans var. gattii. The epidemiology of cryptococcosis can primarily be explained by exposure to an infective aerosolized inoculum, such as basidiospores released from specific host plants and/or desiccated blastoconidia (yeast cells) disseminated from accumulations of dried pigeon dung. The ecology of C. neoformans still remains largely unresolved, studies on the host-parasite interaction between serotype B and E. camaldulensis are still in progress, and extensive environmental searches are now underway to determine the natural habitats of serotypes A, C and D.

Animals↗
PubMed1992

In vivo complement activation and binding of C3 to encapsulated Cryptococcus neoformans.

Tissues from mice infected with Cryptococcus neoformans were examined by immunofluorescence to determine the extent of deposition of complement component C3 on encapsulated cryptococci. The relative percentages of cryptococci in each tissue having readily visible C3 were greatest for liver and lung tissues, with the kidney tissue having the next highest percentage and the spleen having the lowest percentage. Binding of C3 fragments to cryptococci in brain tissue was essentially absent.

Animals↗
PubMed1992

In vitro responses of cheetah mononuclear cells to feline herpesvirus-1 and Cryptococcus neoformans.

In vitro T cell function by domestic cats and cheetahs to two common pathogens, feline herpesvirus-1 (FHV-1) and Cryptococcus neoformans, was assessed. Peripheral blood mononuclear cells (PBM) were stimulated with two strains of UV-inactivated FHV-1, whole heat-killed organisms or capsular antigen of Cryptococcus neoformans, and proliferative responses measured. As a group, cheetah PBM responded significantly poorer than domestic cat PBM when cultured with FHV-1. However, individual cheetah responses varied widely. Supplementation of cultures with exogenous interleukin 2 (IL-2) significantly increased the level of response of individual cheetahs to both strains of FHV-1. Cheetah sera contained slightly higher neutralizing antibody titers to FHV-1 than did domestic cat sera, suggesting that B cells function adequately in cheetahs. When stimulated with Cryptococcus neoformans, both species had similar incidences of positive proliferative responses. These data demonstrate that cheetahs exhibit heterogeneous responses to specific antigens, similar to domestic cats. However, a lower group response to FHV-1 in cheetahs suggests species differences occur. In addition, level of variability in major histocompatibility complex (MHC) class I-like genes, as determined by Southern blot hybridization, does not appear to correlate with a uniform response in in vitro functional assays. Therefore, additional mechanisms influence the final outcome of the immune response.

Acinonyx↗
PubMed1991

False-positive reactions in the latex agglutination test for Cryptococcus neoformans antigen.

The latex agglutination test for Cryptococcus neoformans antigen is a simple and rapid procedure for the diagnosis of cryptococcal meningitis. Although the test is sensitive, care must be taken to prevent contamination of the sample, which may result in false-positive reactions. It was discovered in our laboratory that immersion of a platinum wire inoculating loop into a sample of cerebrospinal fluid prior to testing introduced interfering substances leading to nonspecific agglutination. After further studies, it was determined that trace amounts of surface condensation (syneresis fluid) from agar, either added to the cerebrospinal fluid or adhering to the loop, were the probable source of contamination. It is suggested that the latex agglutination test for C. neoformans antigen be performed prior to culture or on a separate sample.

Antigens, Fungal↗