Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “HISTOPLASMA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources
PubMed2005

Genetic diversity of Histoplasma capsulatum strains in Brazil.

This study establishes the genetic relatedness among Brazilian Histoplasma capsulatum samples obtained from different sources. A PCR-based random amplified polymorphic DNA (RAPD) assay was used to delineate polymorphisms among isolates in geographically diverse regions in Brazil. RAPD fingerprints revealed distinct DNA profiles and provided a high level of discrimination among H. capsulatum strains from different locations. Cluster I was composed of H. capsulatum isolates from the northeast region. The majority of strains from southeast and south were categorized as major cluster II. The strain 84564 from Rio de Janeiro State showed no genetic correlation to any of the isolates from the same state. The RAPD patterns of H. capsulatum isolates from Goias (Cluster III) were unrelated to DNA fingerprints observed among the other H. capsulatum strains (48% similarity). This study is the first report that stratifies the clusters of H. capsulatum strains from Brazil by molecular typing and associates them with the geographical origin.

Animals↗
PubMed2005

Geographical distribution of genetic polymorphism of the pathogen Histoplasma capsulatum isolated from infected bats, captured in a central zone of Mexico.

Fourteen Histoplasma capsulatum isolates recovered from infected bats captured in Mexican caves and two human H. capsulatum reference strains were analyzed using random amplification of polymorphic DNA PCR-based and partial DNA sequences of four genes. Cluster analysis of random amplification of polymorphic DNA-patterns revealed differences for two H. capsulatum isolates of one migratory bat Tadarida brasiliensis. Three groups were identified by distance and maximum-parsimony analyses of arf, H-anti, ole, and tub1 H. capsulatum genes. Group I included most isolates from infected bats and one clinical strain from central Mexico; group II included the two isolates from T. brasiliensis; the human G-217B reference strain from USA formed an independent group III. Isolates from group II showed diversity in relation to groups I and III, suggesting a different H. capsulatum population.

Animals↗
PubMed2005

Histoplasma hairpins herald hopefulness.

Histoplasma capsulatum is a significant respiratory and systemic fungal pathogen. Although many molecular tools have been developed, the fulfillment of Koch's postulates to determine gene function has been hampered by obstacles to homologous gene targeting. Because H. capsulatum displays a considerable array of virulence mechanisms and has a 40-Mb genome that is currently being sequenced, the capability to perform high-throughput molecular manipulations would clearly be beneficial. Recent demonstration and application of experimental RNA interference (RNAi) technology promises a major contribution to advances in this area.

Gene Targeting↗
PubMed1989

Histoplasma capsulatum polysaccharide antigen detection in diagnosis and management of disseminated histoplasmosis in patients with acquired immunodeficiency syndrome.

PURPOSE: Disseminated histoplasmosis is a serious and often rapidly progressive, opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS), supporting the importance of rapid diagnostic tests. We investigated Histoplasma capsulatum polysaccharide antigen (HPA) detection, a promising new method for rapid diagnosis of histoplasmosis. PATIENTS AND METHODS: Sixty-one cases of disseminated histoplasmosis in patients with AIDS form the basis of this report. Control cases were patients with AIDS who had other opportunistic infections and whose cultures were negative for H. capsulatum. A slightly modified radioimmunoassay procedure was used to measure the levels of HPA in urine and blood specimens. RESULTS: High levels of HPA were detected in the urine of 59 of 61 (96.7%) and the blood of 37 of 47 (78.7%) patients with AIDS complicated by disseminated histoplasmosis. Treatment with amphotericin B reduced levels of HPA in the urine in 19 of 21 (90.5%) and the serum of all 10 patients tested. HPA levels increased in the urine in all eight and in the serum in all five patients with culture-proven relapse. CONCLUSION: In conclusion, HPA detection offers a rapid method for diagnosing disseminated histoplasmosis. Additional experience is required to establish the role of this test in monitoring the effects of treatment and in identifying relapse in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Histoplasma granuloma of the conjunctiva.

PURPOSE: To describe the clinical and pathologic features of a conjunctival granuloma resulting from Histoplasma capsulatum. DESIGN: Clinicopathologic case report. METHODS: Surgical excision of conjunctival lesion, histopathologic study with special stains, and a fluorescent antibody technique. RESULTS: A conjunctiva granuloma was found to contain microorganisms, compatible with H. capsulatum, confirmed by a fluorescent antibody technique. The conjunctiva returned to normal. CONCLUSIONS: A focal granuloma of the conjunctiva contained H. capsulatum in a patient whose recent symptoms suggested primary infection. The conjunctival lesion was similar to mucocutaneous lesions seen in patients with systemic histoplasmosis.

Aged↗
PubMed2000

[Histoplasmosis due to Histoplasma capsulatum capsulatum and HIV infection].

PURPOSE: Histoplasmosis due to Histoplasma capsulatum is a granulomatous fungic infection which appears opportunistic and disseminated in immunocompromised patients, especially among HIV patients in whom it can lead to death. Histoplasmosis is endemic in numerous areas worldwide, but in Europe most of the cases reported are imported. We describe the clinical features and the available diagnosis methods issued from our experience in French Guyana. METHODS: Contamination occurs by inhalation of spores contained in dust. Most endemic areas are located on the American continent, including the French West Indies, where the incidence of histoplasmosis among HIV patients in French Guyana varies from 1.2 to 2.2% per year. In non-immunocompromised patients, histoplasmosis is asymptomatic most of the time. In HIV patients, the disseminated form is common and may occur many years after exposure to the fungus. RESULTS: Non-specific symptoms, similar to those of either tuberculosis or other opportunistic infections, may reveal disseminated histoplasmosis in patients with AIDS. Early treatment (amphotericin B or itraconazole) is effective; however, it should be followed by a lifelong antifungic treatment (itraconazole) to prevent relapse. CONCLUSION: The infection should be suspected in any febrile HIV-infected patient with CD4 blood cell count < 200/mm3, if he/she ever travelled in an endemic zone. Direct examination of smear relating to clinical symptoms help guide diagnosis, while culture will confirm it after at least 4 weeks. Efficient serologic techniques for HIV-infected patients are not available in Europe.

AIDS-Related Opportunistic Infections↗
PubMed2000

Determination of beta-glucosidase enzymatic function of the histoplasma capsulatum H antigen using a native expression system.

The Histoplasma capsulatum H antigen is a major secreted glycoprotein of this pathogenic fungus that is a target of humoral and cell-mediated host responses. Its predicted protein sequence displays homology to beta-glucosidases of other organisms, but a recombinant antigen expressed in a prokaryotic system showed no enzymatic activity. We expressed a recombinant form of the protein carrying a carboxyl-terminus oligohistidine tag in the native fungal background to facilitate proper glycosylation and folding of a product that could then be purified from culture supernatants using nickel affinity chromatography. The recombinant protein was expressed and secreted by a transformant carrying the modified gene under the control of its native promoter. The purified protein from the native expression system showed beta-glucosidase enzymatic activity in substrate gels and quantitative microplate assays. This activity was blocked by glucosidase-specific inhibitors. These results are the first direct demonstration of the function of this protein, and show the utility of expression in a native system to achieve post-translational modification necessary for structural and functional integrity.

Antigens, Fungal↗
PubMed1999

Transcript splicing is essential for functional Histoplasma capsulatum URA5 expression.

The isolation of auxotrophic markers is important for molecular genetic studies of the dimorphic fungus Histoplasma capsulatum. We have isolated a UV-induced mutant of H. capsulatum, resulting in nonreverting uracil auxotrophy due to a mutation in the URA5 gene. In this study, we show that this mutation is a GG to TA conversion bordering the 5' donor splice site of intron 2. The mutation results in the lack of splicing of intron 2 from the URA5 transcript, and subsequently premature termination of the peptide. This study is the first showing that consensus Group II intron sequences are both utilized and essential for functional expression of a gene in H. capsulatum.

Gene Expression Regulation, Fungal↗
PubMed1997

Duration of fungal culture incubation in an area endemic for Histoplasma capsulatum.

To determine the optimum incubation period for recovery of fungi from clinical specimens in an area where Histoplasma capsulatum is endemic, we reviewed the results of 4259 consecutive fungal cultures. Of the total 1306 fungi isolated, 92.6% were detected by day 7, and 97.9% were detected by day 14. For the 1027 yeast isolates, only 1.4% were detected after day 7, none of which was considered clinically significant. Of the 281 mould isolates, 91.1% were detected by day 14; and of those detected after day 14, only isolates of H. capsulatum were considered clinically significant. An incubation protocol based on type of specimen is suggested.

Endemic Diseases↗
PubMed2001

Molecular mycology: a genetic toolbox for Histoplasma capsulatum.

Research in medical mycology has traditionally been a mix of exciting biology and frustrating genetics, although the excitement has been steadily increasing as genetic obstacles have been successfully overcome. Now, a variety of fungal pathogens can be studied using molecular techniques derived from classical bacterial and yeast genetics, but with selective and strategic adaptations. Histoplasma capsulatum is the best-studied of the primary pathogens known as 'dimorphic' fungi, and tailored molecular genetic strategies are beginning to reveal a repertoire of genes and gene products intimately associated with pathogenesis.

DNA Transposable Elements↗
PubMed1999

Macrophages in host defense against Histoplasma capsulatum.

Macrophages function in both innate and cell-mediated immunity in host defense against pathogenic fungi. They initially serve as a protected environment in which the primary fungal pathogen Histoplasma capsulatum multiplies and disseminates from the lung to other organs. Upon induction of cell-mediated immunity, cytokines activate macrophages to destroy the yeasts and thus remove them from the host.

Animals↗
PubMed1999

Molecular epidemiology, pathogenesis, and genetics of the dimorphic fungus Histoplasma capsulatum.

Histoplasma capsulatum, the causative agent of the most common systemic fungal infection, histoplasmosis, has become subject to increasing study in parallel with rising prevalence of human immunodeficiency. This review presents a summary of the advances made in the investigation of H. capsulatum genomics, molecular epidemiology, pathogenesis, and molecular genetics.

AIDS-Related Opportunistic Infections↗
PubMed2000

Immune response to early and late Histoplasma capsulatum infections.

Knowledge of the host response to the intracellular pathogenic fungus Histoplasma capsulatum has increased dramatically. Information has accumulated regarding the cellular and molecular determinants that lead to resolution of both primary and secondary infection. The significance of cytokines and other endogenous soluble mediators to the protective immune response have been analyzed. Moreover, work concerning the relative importance of T cell subsets to protective immunity has been initiated.

Animals↗
PubMed2003

Knocking on the right door and making a comfortable home: Histoplasma capsulatum intracellular pathogenesis.

Histoplasma capsulatum is a successful intracellular pathogen of mammalian macrophages. As such, this fungus must survive and/or subvert hostile environmental onslaughts in a professionally antimicrobial host cell. H. capsulatum uses different host receptors for binding to macrophages (beta 2 integrins) than it uses for binding to dendritic cells (the fibronectin receptor); the fungus experiences different degrees of success in survival in these two cells. Surface expression of HSP60 as the specific adhesin for macrophage beta 2 integrins represents a novel mechanism for binding. Long considered a resident of the phagolysosome, H. capsulatum may also reside in a modified phagosome without experiencing phagolysosomal fusion. H. capsulatum must compete with the host to acquire the essential nutrient iron, and has several potential mechanisms for accomplishing this necessary feat. Finally, H. capsulatum displays morphotype-specific expression of several genes, and a calcium-binding protein expressed only by the pathogenic yeast phase has been demonstrated as essential for full virulence. An organism's environment is of great importance to its success or failure, and H. capsulatum is good at finding or making the right environment in the host.

Animals↗
PubMed1983

Purification and characterization of a cysteine dioxygenase from the yeast phase of Histoplasma capsulatum.

A cysteine dioxygenase, cysteine oxidase (EC 1.13.11.20), has been purified from the cytosolic fraction of yeast phase cells of the dimorphic fungus Histoplasma capsulatum. The cysteine oxidase is an iron-containing dioxygenase with a molecular weight of 10500 (+/- 1500) and is present only in the yeast phase of the fungus. The enzyme is highly specific for L-cysteine, with a Km of 2 X 10(-5) M in vitro. The product of cysteine oxidation is cysteinesulfinic acid, as analyzed by thin-layer chromatography and mass spectroscopy. To our knowledge, this is the first cysteine oxidase isolated from a fungus, and it probably plays an important role in the mycelial to yeast phase transition of H. capsulatum during which redox potential and cysteine levels are crucial factors.

Cysteine Dioxygenase↗
PubMed1984

Occurrence of novel antigenic phosphoinositol-containing sphingolipids in the pathogenic yeast Histoplasma capsulatum.

Five alkali-stable lipids from the yeast phase of Histoplasma capsulatum have been purified and analyzed. Each compound has equimolar amounts of hydroxysphinganine (phytosphingosine) and a hydroxy or nonhydroxy 24:0 fatty acid. All yield inositol phosphate after acid hydrolysis, and several are novel in that they also yield dimannosylinositol (compound V) and isomeric galactosyldimannosylinositols (compounds VI and VIII) after strong ammonolysis. The foregoing as well as other data suggest that compound V is a dimannosylinositolphosphoceramide and compounds VI and VIII are galactosyldimannosylinositolphosphoceramides with isomeric head groups. The chromatographic behavior of compounds II and III indicates that they are similar to the inositolphosphoceramides previously observed in Saccharomyces cerevisiae. Compounds V and VI are virtually absent from the mycelial phase of H. capsulatum. Antibodies that react with compounds V, VI, and VIII have been detected in sera from patients with histoplasmosis.

Antibody Specificity↗
PubMed1984

Carbohydrate structures of three novel phosphoinositol-containing sphingolipids from the yeast Histoplasma capsulatum.

From the yeast phase of the human pathogen Histoplasma capsulatum, three novel glycolipids were isolated, shown to react with sera from histoplasmosis patients, and partially characterized: compound V, ceramide-P-inositol-[mannose2]; compound VI, ceramide-P-inositol-[mannose2, galactose]; compound VIII, an isomer of compound VI [Barr, K., & Lester, R.L. (1984) Biochemistry (preceding paper in this issue)]. Ammonolysis of these lipids has yielded all the carbohydrate (oligosaccharides V, VI, and VIII) as novel, intact oligosaccharides suitable for characterization. Anomeric configurations were determined by specific glycosidase digestion and by the stability of peracetylated saccharides to CrO3 oxidation. Linkages were established by methylation analysis. These experiments yielded the following structural assignments: (formula; see text) The occurrence of galactofuranose is novel for glycosphingolipids, and it is noteworthy that compound VI is immunoreactive.

Carbohydrate Conformation↗
PubMed1980

Comparison of the ribonucleic acid polymerases from both phases of Histoplasma capsulatum.

The three ribonucleic acid (RNA) polymerases (ribonucleoside triphosphate RNA nucleotidyltransferases, EC 2.7.7.6) of the two phases (yeast and mycelial) of the dimorphic fungus Histoplasma capsulatum have been purified and characterized. The corresponding enzymes from the two phases differ in sensitivity to alpha-amanitin, ion and salt requirements, temperature sensitivity, and subunit structure. This is the first case in which such qualitative differences in RNA polymerases have been demonstrated in two growth states of the same organism.

Amanitins↗