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Cryptococcus Neoformans (Cryptococcu + neoforman)
Selected AbstractsStimulation via Toll-like receptor 9 reduces Cryptococcus neoformans -induced pulmonary inflammation in an IL-12-dependent mannerEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2005Lorna Edwards Abstract Cytosine-phosphate-guanosine-containing oligodeoxynucleotides (CpG ODN) are important vaccine adjuvants that promote Th1-type immune responses. Cryptococcus neoformans is a serious human pathogen that replicates in the lung but may disseminate systemically leading to meningitis, particularly in immunocompromised individuals. Immunization of susceptible C57BL/6 mice with CpG ODN deviates the immune response from a Th2- toward a Th1-type response following infection with C. neoformans. CpG also induces IL-12, TNF, MCP-1 and macrophage nitric oxide production. CD4+ and CD8+ T,cells producing IFN-, increase in frequency, while those producing IL-5 decrease. More importantly, pulmonary eosinophilia is significantly reduced, an effect that depends on IL-12 and CD8+ T,cells but not NK cells. CpG treatment also reduces the burden of C. neoformans in the lung, an effect that is IL-12-, NK cell- and T,cell-independent and probably reflects a direct effect of CpG on pathogen opsonization or an enhancement of macrophage antimicrobial activity. An equivalent beneficial effect is also observed when CpG ODN treatment is delivered during established cryptococcal disease. This is the first study documenting that promotion of lung TLR9 signaling using synthetic agonists enhances host defense. Activation of innate immunity has clear therapeutic potential and may even be beneficial in patients with acquired immune deficiency. [source] The single Cdk1-G1 cyclin of Cryptococcus neoformans is not essential for cell cycle progression, but plays important roles in the proper commitment to DNA synthesis and bud emergence in this yeastFEMS YEAST RESEARCH, Issue 5 2010Eric V. Virtudazo Abstract The cell cycle pattern of the pathogenic basidiomycetous yeast Cryptococcus neoformans differs from that of the ascomycetous budding yeast Saccharomyces cerevisiae. To clarify the cell cycle control mechanisms at the molecular level, homologues of cell cycle control genes in C. neoformans were cloned and analyzed. Here, we report on the cloning and characterization of genes coding for CDK1 cyclin homologues, in particular, the C. neoformans G1 cyclin. We have identified three putative CDK1 cyclin homologues and two putative CDK5 (PHO85) cyclin homologues from the genome. Complementation tests in an S. cerevisiae G1 cyclin triple mutant confirmed that C. neoformans CLN1 is able to complement S. cerevisiae G1 cyclin deficiency, demonstrating that it is a G1 cyclin homologue. Interestingly, cells deleted of the single Cdk1-G1 cyclin were viable, demonstrating that this gene is not essential. However, it exhibited aberrant budding and cell division and a clear delay in the initiation of DNA synthesis as well as an extensive delay in budding. The fact that the mutant managed to traverse the G1 to M phase may be due to the activities of Pho85-related G1 cyclins. Also, that C. neoformans had only a single Cdk1-G1 cyclin highlighted the importance of keeping in order the commitment to the initiation of DNA synthesis first and then that of budding, as discussed. [source] Genotype and mating type analysis of Cryptococcus neoformans and Cryptococcus gattii isolates from China that mainly originated from non-HIV-infected patientsFEMS YEAST RESEARCH, Issue 6 2008Xiaobo Feng Abstract Cryptococcosis has been reported to be mostly associated with non-HIV-related patients in China. However, little is known about the molecular characteristics of clinical isolates from the Cryptococcus neoformans species complex in this country. In this study, 115 clinical isolates were included. Molecular type VNI was the most representative (n=103), followed by VGI (n=8), VNIII (n=2), VNIV (n=1), and VGII (n=1). With the exception of a serotype D mating type a isolate, all possessed the MAT, locus. Multilocus sequence typing (MLST) revealed that most Cryptococcus gattii isolates from China shared identical MLST profiles with the most common MLST genotype reported in the VGI group, and the only one VGII isolate resembled the Vancouver Island outbreak minor genotype. The C. gattii strains involved in this study were successfully grouped according to their molecular type and mating types by PCR-restriction fragment length polymorphism (RFLP) analysis of the GEF1 gene. Our results suggest that (1) in China, cryptococcosis is mostly caused by C. neoformans var. grubii (molecular type VNI), and mating type ,; (2) The most common causative agents of C. gattii infection in China are closely related to a widely distributed MLST genotype; and (3) The PCR-RFLP analysis of the GEF1 gene has the potential to identify the molecular and mating types of C. gattii simultaneously. [source] Extracellular glycosylphosphatidylinositol-anchored mannoproteins and proteases of Cryptococcus neoformansFEMS YEAST RESEARCH, Issue 4 2007Richard A. Eigenheer Abstract Extracellular proteins of Cryptococcus neoformans are involved in the pathogenesis of cryptococcosis, and some are immunoreactive antigens that may potentially serve as candidates for vaccine development. To further study the extracellular proteome of the human fungal pathogen Cry. neoformans, we conducted a proteomic analysis of secreted and cell wall-bound proteins with an acapsular strain of Cry. neoformans. Proteins were identified from both intact cells and cell walls. In both cases, extracellular proteins were removed with trypsin or ,-glucanase, and then all proteins/peptides were purified by solid-phase extraction, spin dialysis, and HPLC, and identified by liquid chromatography,mass spectrometry. This study identified 29 extracellular proteins with a predicted N-terminal signal sequence and also a predicted glycosylphosphatidylinositol anchor motif in more than half. Among the novel proteins identified were five glycosylphosphatidylinositol-anchored proteins with extensive Ser/Thr-rich regions but no apparent functional domains, a glycosylphosphatidylinositol-anchored aspartic protease, and a metalloprotease with structural similarity to an elastinolytic metalloprotease of Aspergillus fumigatus. This study suggests that Cry. neoformans has the machinery required to target glycosylphosphatidylinositol-anchored proteins to the cell wall, and it confirms the extracellular proteolytic ability of Cry. neoformans. [source] Contemplating the murine test tube: lessons from natural killer cells and Cryptococcus neoformansFEMS YEAST RESEARCH, Issue 4 2006Kaleb J. Marr Abstract Murine experimentation has provided many useful tools, including the ability to knockout or over-express genes and to perform experiments that are limited by ethical considerations. Over the past century, mice have imparted valuable insights into the biology of many systems, including human immunity. However, although there are many similarities between the immune response of humans and mice, there are also many differences; none is more prominent than when examining natural killer cell biology. These differences include tissue distribution, effector molecules, receptor repertoire, and cytokine responses, all of which have important implications when extrapolating the studies to the human immune responses to Cryptococcus neoformans. [source] Application of proton nuclear magnetic resonance spectroscopy to the study of Cryptococcus and cryptococcosisFEMS YEAST RESEARCH, Issue 4 2006Tania C. Sorrell Abstract Proton nuclear magnetic resonance spectroscopy is a nondestructive technique that identifies chemicals in solution and in living cells. It has been used in cryptococcal research to identify the primary structure of capsular glucuronoxylomannans, link cellular apoptosis susceptibility (CAS) genes to positioning of residues on the mannose backbone of glucuronoxylomannan, and verify that the cryptococcal virulence determinant, phospholipase B, is elaborated in vivo. Promising clinical applications include speciation (Cryptococcus neoformans and Cryptococcus gattii), with preliminary evidence that varieties neoformans and grubii can also be distinguished, non-invasive diagnosis of cerebral cryptococcomas, and, in cases of meningitis, monitoring therapeutic response by analysis of cerebrospinal fluid. [source] Two-component signal transduction in human fungal pathogensFEMS YEAST RESEARCH, Issue 2 2006Michael Kruppa Abstract Signal transduction pathways provide mechanisms for adaptation to stress conditions. One of the most studied of these pathways is the HOG1 MAP kinase pathway that in Saccharomyces cerevisiae is used to adapt cells to osmostress. The HOG1 MAPK has also been studied in Candida albicans, and more recently observations on the Hog1p functions have been described in two other human pathogens, Aspergillus fumigatus and Cryptococcus neoformans. The important, but not surprising, concept is that this pathway is used for different yet similar functions in each of these fungi, given their need to adapt to different environmental signals. Current studies of C. albicans focus upon the identification of two-component signal proteins that, in both C. albicans and S. cerevisiae, regulate the HOG1 MAPK. In C. albicans, these proteins regulate cell wall biosynthesis (and, therefore, adherence to host cells), osmotic and oxidant adaptation, white-opaque switching, morphogenesis, and virulence of the organism. [source] Role of laccase in the biology and virulence of Cryptococcus neoformansFEMS YEAST RESEARCH, Issue 1 2004Xudong Zhu Abstract Laccase is an important virulence factor for the human pathogen, Cryptococcus neoformans. In this review, we examine the structural, biological and genetic features of the enzyme and its role in the pathogenesis of cryptococcosis. Laccase is expressed in C. neoformans as a cell wall enzyme that possesses a broad spectrum of activity oxidizing both polyphenolic compounds and iron. Two paralogs, CNLAC1 and CNLAC2, are present in the fungus, of which the first one expresses the dominant enzyme activity under glucose starvation conditions. Regulation of the enzyme is in response to various environmental signals including nutrient starvation, the presence of multivalent cations and temperature stress, and is mediated through multiple signal transduction pathways. Study of the function and regulation of this important virulence factor has led to further understanding of mechanisms of fungal pathogenesis and the regulation of stress response in the host cell environment. [source] Cryptococcus neoformans capsule biosynthesis and regulationFEMS YEAST RESEARCH, Issue 8 2004Guilhem Janbon Abstract The capsule is certainly the most prominent virulence factor in Cryptococcus neoformans: acapsular strains are avirulent, and capsular polysaccharides have a deleterious effect on the immune system. Until very recently, very few genes involved in capsule biosynthesis had been identified , and this despite the existence of a detailed body of work concerning the capsule's composition, structure and their regulation by environmental factors. The tremendous development of experimental tools and techniques suited to the study of C. neoformans biology together with the sequencing of three complete genomes have, over the last three years, enabled the identification of a number of proteins which participate directly in biosynthesis of the capsule or which regulate its size. Even though this knowledge is still preliminary, it gives us a clearer picture of the various events needed for biosynthesis of this fascinating structure. [source] Cryptococcal infection in sarcoidosisINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 11 2002Khosrow Mehrany MD A 48-year-old man with a history of sarcoidosis was transferred to the Mayo Clinic for evaluation and management of progressive neurologic decline. Two years before admission, he was admitted to a local hospital with mental status changes accompanied by ataxia and severe headache. A diagnosis of pulmonary and central nervous system sarcoidosis was made based on computed tomography of the head, lumbar puncture, and chest radiography. A mediastinoscopy with lymph node biopsy exhibited noncaseating granulomas and negative stains for microorganisms. Prednisone therapy was initiated at 80 mg/day. Clinical improvement was apparent for 13 months during steroid therapy until the slow taper reached a dosage of 20 mg/day. At that time, the patient was readmitted to the local hospital with severe confusion and skin lesions. When intravenous methylprednisolone therapy for presumed central nervous system sarcoidosis did not improve the patient's mental status, he was transferred to the Mayo Clinic. Physical examination of the thighs revealed large, well-marginated, indurated, irregularly bordered, violaceous plaques and rare, umbilicated, satellite papules with central hemorrhagic crusts (Fig. 1A). Superficially ulcerated plaques with a similar appearance to the thigh lesions were coalescing around the lower legs (Fig. 1B). A skin biopsy specimen of the thigh demonstrated abundant numbers of encapsulated organisms and minimal inflammatory response (Fig. 2). Skin, blood, and cerebrospinal fluid cultures confirmed the presence of Cryptococcus neoformans. Amphotericin and flucytosine combination therapy was initiated, and steroid dosages were gradually tapered. A test for human immunodeficiency virus was negative. The patient was dismissed from hospital after a complicated 2-month course resulting in improved mental status but progression of the lower extremity ulcerations as a result of polymicrobial infection. Figure 1. (A) Violaceous plaque with satellite papules on thigh. (B) Ulcerating plaques coalescing around leg Figure 2. (A) Sparse inflammatory infiltrate and abundant encapsulated organisms (hematoxylin and eosin; × 20). (B) Cryptococcal organisms (Gomori's methenamine silver; × 40) [source] Cyanobacteria from benthic mats of Antarctic lakes as a source of new bioactivitiesJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2008N. Biondi Abstract Aims:, To exploit the cyanobacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes for the discovery of novel antibiotic and antitumour activities. Methods and results:, In all, 51 Antarctic cyanobacteria isolated from benthic mats were cultivated in the laboratory by optimizing temperature, irradiance and mixing. Productivity was generally very low (,60 mg l,1 d,1) with growth rates (,) in the range of 0·02,0·44 d,1. Growth rates were limited by photosensitivity, sensitivity to air bubbling, polysaccharide production or cell aggregation. Despite this, 126 extracts were prepared from 48 strains and screened for antimicrobial and cytotoxic activities. Seventeen cyanobacteria showed antimicrobial activity (against the Gram-positive Staphylococcus aureus, the filamentous fungus Aspergillus fumigatus or the yeast Cryptococcus neoformans), and 25 were cytotoxic. The bioactivities were not in accordance with the phylogenetic grouping, but rather strain-specific. One active strain was cultivated in a 10-l photobioreactor. Conclusions:, Isolation and mass cultivation of Antarctic cyanobacteria and LC-MS (liquid chromatography/mass spectrometry) fractionation of extracts from a subset of those strains (hits) that exhibited relatively potent antibacterial and/or antifungal activities, evidenced a chemical novelty worthy of further investigation. Significance and impact of the study:, Development of isolation, cultivation and screening methods for Antarctic cyanobacteria has led to the discovery of strains endowed with interesting antimicrobial and antitumour activities. [source] Inhibition of clinical and environmental Cryptococcus neoformans isolates by two Brazilian killer yeastsJOURNAL OF BASIC MICROBIOLOGY, Issue 2 2006Alexandre M. Fuentefria Two killer yeast strains (HB55 and HB88) capable of inhibiting human pathogenic fungi were isolated from leaves of Hibiscus rosa-sinensis in Brazil. These isolates were identified by conventional methods and sequencing of the D1/D2 region of the 26S rDNA as Kodamaea ohmeri . They inhibited all Cryptococcus neoformans (vars. neoformans , grubii and gattii ) strains tested, including reference, clinical and environmental isolates. The killer phenotype was not cured by thermal treatment. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Preemptive treatment of fungal infection: has its time arrived in liver transplantation?LIVER TRANSPLANTATION, Issue 3 2008James D. Perkins M.D. Special Editor Background Invasive fungal infection remains a major challenge in liver transplantation and the mortality rate is high. Early diagnosis and treatment are required for better results. Patients We prospectively measured plasma (1 , 3),-d glucan (BDG) levels in 180 living donor liver transplant recipients for 1 year after surgery. Fungal infection was defined as proposed by the European Organization for Research and Treatment of Cancer/Mycoses Study Group. Preemptive treatment (intravenous fluconazole and trimethoprim-sulfamethoxazole) was started when the BDG level was greater than 40 pg/ml. Results Twenty-four patients (13%) were diagnosed with invasive fungal infection. The responsible pathogens included Candida spp. in 14 cases, Aspergillus fumigatus in 5, Cryptococcus neoformans in 3, and Pneumocystis jiroveci in 2. Preemptive treatment was performed in 22% of patients (n = 40). Renal impairment and mild gastrointestinal intolerance due to the drugs were observed in 28% (11/40) of patients during treatment. Among them 14 patients were diagnosed with fungal infection including seven candidiasis, five aspergillosis, and two Pneumocystis jiroveci pneumonia. The sensitivity and specificity of BDG for overall fungal infection was 58% and 83%, respectively, with a positive predictive value of 35% and a negative predictive value of 93%, and a positive likelihood ratio of 3.41 and a negative likelihood ratio of 1.98. The overall mortality for fungal infection in our series was 0.6%. Conclusion Although the sensitivity and positive predictive value were low, the low mortality rate after fungal infection and the mild side effects of the preemptive treatment might justify our therapeutic strategy. Based on the effectiveness, this strategy warrants further investigation. [source] Cell wall ,-1,3-glucan is required to anchor the Cryptococcus neoformans capsuleMOLECULAR MICROBIOLOGY, Issue 4 2003Amy J. Reese Summary Cryptococcus neoformans is an opportunistic pathogen responsible for serious disease in humans. Critical for virulence of this fungus is an elaborate polysaccharide capsule, which impedes the host immune response. We found that association of the capsule with the cell requires a specific component of the cell wall, ,-1,3-glucan. Post-transcriptional inhibition of ,-1,3-glucan synthase expression, using double-stranded RNA interference, yields cells that are unable to assemble a capsule although they generate its polysaccharide components. The resulting cryptococci are slow-growing and acapsular. This finding demonstrates a novel mode of polysaccharide attachment and an important application of RNA interference in fungi. The elimination of the capsule by reducing the expression of a single gene suggests a potential avenue for antifungal chemotherapy. [source] Copper-mediated reversal of defective laccase in a ,vph1 avirulent mutant of Cryptococcus neoformansMOLECULAR MICROBIOLOGY, Issue 4 2003Xudong Zhu Summary Previous studies have shown that a ,vph1 Cryptococcus neoformans mutant defective in vesicular acidification lacked several important virulence factors including a copper-containing laccase and was avirulent in a mouse model. In the present studies, we characterized laccase transcription and protein production to obtain insights into the mechanism of the vph1 mutation in this pathogen. Although transcription and protein expression were somewhat reduced, laccase protein was found to be successfully translated and correctly targeted to the cell wall in the ,vph1 mutant as shown by Western blot and immuno-electron microscopy, despite a complete lack of laccase activity. Laccase activity was substantially restored in metabolically active ,vph1 cells at 30°C by addition of 100 µM copper sulphate. This restoration by copper was found to occur through both transcriptional and post-translational mechanisms. Laccase transcriptional induction by copper was found to be dependent on enhancer region II within the 5,-untranslated region of CNLAC1. Copper was also found to restore partial activity to ,vph1 cells at 0°C, suggesting that cell wall laccase was expressed in the mutant as an apo-enzyme. Apo-laccase restoration by copper was found to be facilitated by an acidic environment, consistent with a role for the vacuolar (H+)-ATPase proton pump in copper assembly of laccase in C. neoformans. [source] Multiple virulence factors of Cryptococcus neoformans are dependent on VPH1MOLECULAR MICROBIOLOGY, Issue 4 2001Todd Erickson Acidification of vesicular compartments plays an important role in a number of cellular transport processes, including protein secretion, metal cofactor insertion, glycosylation and pH stability. In the present study, we identify and characterize a component of the vesicular proton pump, Vph1p, to determine its role in the virulence of the AIDS-related fungal pathogen Cryptococcus neoformans. Insertional mutagenesis and plasmid rescue were used to identify the VPH1 gene by screening for mutants defective in laccase activity. Disruption of VPH1 resulted in defects in three virulence factors (capsule production, laccase and urease expression), as well as a growth defect at 37°C, but only a small growth reduction at 30°C. These effects were duplicated by the vacuolar (H+)-ATPase inhibitor bafilomycin A1. Furthermore, the vph1 insertional mutant was also avirulent in a mouse meningo-encephalitis model. Complementation of the insertional mutant with wild-type VPH1 resulted in a recovery of virulence factor expression, normal growth at 37°C and restoration of full virulence. These studies establish the importance of the VPH1 gene and vesicular acidification in the virulence of C. neoformans. [source] Calcineurin regulatory subunit is essential for virulence and mediates interactions with FKBP12,FK506 in Cryptococcus neoformansMOLECULAR MICROBIOLOGY, Issue 4 2001Deborah S. Fox Calcineurin is a Ca2+,calmodulin-regulated protein phosphatase that is the target of the immunosuppressive drugs cyclosporin A and FK506. Calcineurin is a heterodimer composed of a catalytic A and a regulatory B subunit. In previous studies, the calcineurin A homologue was identified and shown to be required for growth at 37°C and hence for virulence of the pathogenic fungus Cryptococcus neoformans. Here, we identify the gene encoding the calcineurin B regulatory subunit and demonstrate that calcineurin B is also required for growth at elevated temperature and virulence. We show that the FKR1-1 mutation, which confers dominant FK506 resistance, results from a 6 bp duplication generating a two-amino-acid insertion in the latch region of calcineurin B. This mutation was found to reduce FKBP12,FK506 binding to calcineurin both in vivo and in vitro. Molecular modelling based on the FKBP12,FK506,calcineurin crystal structure illustrates how this mutation perturbs drug interactions with the phosphatase target. In summary, our studies reveal a central role for calcineurin B in virulence and antifungal drug action in the human fungal pathogen C. neoformans. [source] Characterisation of the CipC-like protein AFUA_5G09330 of the opportunistic human pathogenic mould Aspergillus fumigatusMYCOSES, Issue 4 2010Bettina Bauer Summary,Aspergillus fumigatus is currently the major airborne fungal pathogen that menaces immunocompromised individuals. Germination of inhaled conidia is a hallmark of the early infection process, but little is known about the underlying mechanisms. The intention of our ongoing studies is the identification of A. fumigatus proteins that are differentially expressed during germination and may provide insights in the germination process. Using a proteomic approach, we identified AFUA_5G09330 as a major hyphal-specific protein. This result was confirmed using monoclonal antibodies generated in this study. AFUA_5G09330 belongs to a fungal-specific protein family. The eponymous CipC protein of A. nidulans has been shown to be induced by concanamycin A, and transcriptional data from Cryptococcus neoformans demonstrate a strong up-regulation of the expression of a homologous gene during infection. Our data provide evidence that AFUA_5G09330 is a monomeric, cytoplasmic protein. We found no evidence for an overexpression of AFUA_5G09330 induced by concanamycin A or other stress conditions. AFUA_5G09330 is exclusively found in the hyphal morphotype that enables an invasive growth of A. fumigatus during infection. Further studies are required to define the biological function of this hyphae-specific protein and its potential relevance for the pathogenicity of A. fumigatus. [source] Müeller,Hinton methylene blue media as an alternative to RPMI 1640 for determining the susceptibility of Cryptococcus neoformans and Cryptococcus gattii to posaconazole with EtestMYCOSES, Issue 2 2010Eidi Alvarado-Ramírez Summary Mueller,Hinton modified agar (MH-GMB) was compared with RPMI + 2% glucose,agar to determine the MICs of 80 isolates of Cryptococcus neoformans and C. gattii to posaconazole with Etest. MH-GMB minimised trailing and agreement between both media was 94%. Agreement of M27-A2 microbroth reference method was 98% with RPMI and 94% with MB-GMB. [source] Comparative evaluation of Candi Select test and conventional methods for identification of Candida albicans in routine clinical isolatesMYCOSES, Issue 3-4 2002S. Foongladda Candida albicans; Identifizierung; Candi Select- Test; Bewertung. Summary. The Candi Select test (Sanofi Diagnostics, Pasteur, Marnes-La-Coquette, France) is a new yeast-selective medium for the identification of Candida albicans in the clinical laboratory. The performance of this test was compared with the conventional methods of chlamydospore formation, germ tube formation and carbohydrate fermentation. Four hundred and twenty clinical yeast isolates from 412 fresh clinical specimens, including 283 C. albicans, 59 C. tropicalis, 39 Trichosporon spp., 19 C. glabrata, 11 Cryptococcus neoformans and 9 other yeasts, were evaluated. Colonies of C. albicans produced a blue-green colour on the Candi Select media which could be distinguished from the other yeasts with the naked eye within 24,48 h. The sensitivity and specificity of the Candi Select test for the identification of C. albicans were 99.65% and 97.08%, respectively. The blue-green colonies of C. albicans were easy to identify and recognize in mixed cultures and did not need detailed microscopic examination. Zusammenfassung., Der Candi Select-Test (Sanofi Diagnostics Pasteur, Marnes-La-Coquette, Frankreich) ist ein neuer selektiver Nährboden für die Identifizierung von Candida albicans im klinischen Labor. Die neue Methode wurde mit den konventionellen Methoden der Chlamydosporenbildung, der Keimschlauchbildung und der Kohlenhydrat-Gärung verglichen. Vierhundertzwanzig Hefeisolate, nämlich 283 C. albicans, 59 Candida tropicalis, 39 Trichosporon spp., 19 Candida glabrata, 11 Cryptococcus neoformans und 9 andere Hefen, isoliert aus 412 frischen klinischen Untersuchungsproben, wurden mit allen Methoden untersucht. Mit blossem Auge erkennbar, unterschieden sich innerhalb von 24,48 Stunden die blau-grünen Farbkolonien von C. albicans von allen anderen Hefen auf dem Candi Select Nährboden. Sensitivität und Spezifizität des Candi Select Tests für die Identifizierung von C. albicans betrugen 99.65% und 97.08%. Die blau-grünen Farbkolonien von C. albicans waren in den Mischkulturen leicht zu identifizieren, eine mikroskopische Untersuchung erübrigt sich daher. [source] In Vitro antifungal activity of extract and plumbagin from the stem bark of Diospyros crassiflora Hiern (Ebenaceae)PHYTOTHERAPY RESEARCH, Issue 7 2007J. P. Dzoyem Abstract In this study the methanol/dichloromethane (1:1) extract and plumbagin isolated from extract of stem barks of Diospyros crassiflora were tested for their antifungal activity against 12 strains of yeast pathogens and filamentous fungi: Candida albicans, Candida glabrata, Candida krusei, Candida tropicalis, Cryptococcus neoformans, Aspergillus niger, Aspergillus flavus, Alternaria sp., Cladosporium sp., Geotrichum candidum, Fusarium sp. and Penicillium sp. The growth of all fungi strains tested was inhibited by the extract and plumbagin. The diameter of inhibition zones varied from 12 to 18 mm and from 21 to 35 mm for the extract and plumbagin, respectively. The MIC values ranged from 12.5 to 25 mg/mL for the extract and 0.78,3.12 µg/mL for plumbagin. It is therefore suggested that extracts from the stem bark of Diospyros crassiflora could be used traditionally in the treatment of fungal infections. Compared with ketoconazole used as a standard antifungal, plumbagin could be considered as a promising antifungal agent. Copyright © 2007 John Wiley & Sons, Ltd. [source] HIV-associated opportunistic pneumoniasRESPIROLOGY, Issue 4 2009Laurence HUANG ABSTRACT Among the HIV-associated pulmonary complications, opportunistic pneumonias are major causes of morbidity and mortality. The spectrum of HIV-associated opportunistic pneumonias is broad and includes bacterial, mycobacterial, fungal, viral and parasitic pneumonias. Bacterial pneumonia is the most frequent opportunistic pneumonia in the United States and Western Europe while tuberculosis is the dominant pathogen in sub-Saharan Africa. With the use of combination antiretroviral therapy and prophylaxis, the incidence of Pneumocystis pneumonia (PCP) has declined. Nevertheless, PCP continues to occur in persons who are unaware of their HIV infection, those who fail to access medical care, and those who fail to adhere to antiretroviral therapy or prophylaxis. Although pneumonias due to Cryptococcus neoformans, Histoplasma capsulatum, Coccidioides immitis, cytomegalovirus and Toxoplasma gondii are less frequent, their presence in the lung is often indicative of disseminated disease and is associated with significant mortality. [source] Cellulitis Revealing a Cryptococcosis-Related Immune Reconstitution Inflammatory Syndrome in a Renal Allograft RecipientAMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2007F. Lanternier Immune reconstitution inflammatory syndrome (IRIS) has rarely been described in the course of disseminated cryptococcosis in solid organ transplant recipients. We report here the case of a renal transplant recipient who developed severe cellulitis in the context of Cryptococcus neoformans -associated IRIS while undergoing reduction of his immunosuppressive therapy. IRIS appeared concomitantly with a dramatic increase of blood CD4+ T cells (94,460/mm3) and required the administration of a short-term steroid therapy to resolve. [source] A novel monoclonal antibody recognizing ,(1,3) glucans in intact cells of Candida and Cryptococcus,APMIS, Issue 10 2008N. KONDORI The cell walls of all medically important fungi contain a unique polyglucose compound, ,(1,3) glucan. In the present study, murine monoclonal antibodies were produced against linear and ,(1,6) branched ,(1,3) glucans, and their specificities were characterized for reactivity to other , glucans, fungal cell wall fragments, and fungal cells. Their reactivity was also compared with that of rabbit polyclonal antibodies raised against the same immunogens. Two mouse monoclonal antibodies (AG and BG) recognized immunoreactive epitopes in ,(1,3)(1,6) glucan by ELISA. In an inhibition assay of the anti-,(1,3)(1,6) activity of the monoclonals, the homologous antigen effectively inhibited the activity as expected, while ,(1,3) also inhibited the assay but to a much lesser extent. No inhibition was obtained by ,(1,3)(1,4) or ,(1,6), while a cell wall extract of Candida albicans (PPM) effectively inhibited both monoclonals. Cell wall fragments of C. albicans (CaCW) and Cryptococcus neoformans (CnCW) inhibited the anti-,(1,3)(1,6) activity of AG, while BG was much less or not inhibited at all. Immunofluorescence confirmed the unique antibody specificity of AG by its recognition of a ,(1,3)(1,6)-associated epitope on the cell surfaces of C. albicans,C. krusei, C. glabrata, and nonencapsulated C. neoformans. The epitope for the AG antibody is suggested to be present in the branching point of ,(1,3)(1,6), or in the randomly coiled ,(1,3) polyglucan due to the presence of branches. Thus, monoclonal antibodies to ,(1,3)(1,6) glucans may have potential as tools in the laboratory diagnosis of invasive yeast infections. [source] Fungicide Activity of 5-(4-Chlorobenzylidene)-(Z)-2-dimethylamino-1,3-thiazol-4-one against Cryptococcus NeoformansARCHIV DER PHARMAZIE, Issue 1 2010Braulio Insuasty Abstract The present work describes the synthesis and antifungal evaluation of new 5-arylidene-(Z)-2-dimethylamino-1,3-thiazol-4-ones 4a,f, obtained by the reaction of aromatic aldehydes 1 and rhodanine 2 followed by treatment with DMF. All compounds were tested against a panel of yeasts, hialohyphomycetes, and dermatophytes using the microbroth dilution method. Compounds 4a and 4c showed antifungal activity, with compound 4a being the most active one. Compound 4a demonstrated to be fungicidal rather than fungistatic and selective activity against Cryptococcus neoformans and dermatophytes. MIC100, MIC80, and MIC50 of 4a were determined against a panel of clinical isolates of C. neoformans showing ranges of MICs between 2 and 16 ,g/mL. [source] The structure of Cryptococcus neoformans thymidylate synthase suggests strategies for using target dynamics for species-specific inhibitionACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2005Robert H. O'Neil The ternary complex crystal structures of Cryptococcus neoformans and Escherichia coli thymidylate synthase (TS) suggest mechanisms of species-specific inhibition of a highly conserved protein. The 2.1,Å structure of C. neoformans TS cocrystallized with substrate and the cofactor analog CB3717 shows that the binding sites for substrate and cofactor are highly conserved with respect to human TS, but that the structure of the cofactor-binding site of C. neoformans TS is less constrained by surrounding residues. This feature might allow C. neoformans TS to form TS,dUMP,inhibitor complexes with a greater range of antifolates than human TS. 3,,3,,-Dibromophenol-4-chloro-1,8-naphthalein (GA9) selectively inhibits both E. coli TS and C. neoformans TS (Ki = 4,µM) over human TS (Ki >> 245,µM). The E. coli TS,dUMP,GA9 complex is in an open conformation, similar to that of the apoenzyme crystal structure. The GA9-binding site overlaps the binding site of the pABA-glutamyl moiety of the cofactor. The fact that human apoTS can adopt an unusual fold in which the GA9-binding site is disordered [Phan et al. (2001), J. Biol. Chem.276, 14170,14177] may explain the poor affinity of GA9 for the human enzyme. These observations highlight the critical need to incorporate multiple target conformations in any computational attempt to facilitate drug discovery. [source] Crystallization and preliminary X-ray analysis of mycophenolic acid-resistant and mycophenolic acid-sensitive forms of IMP dehydrogenase from the human fungal pathogen CryptococcusACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2010Carl A. Morrow Fungal human pathogens such as Cryptococcus neoformans are becoming an increasingly prevalent cause of human morbidity and mortality owing to the increasing numbers of susceptible individuals. The few antimycotics available to combat these pathogens usually target fungal-specific cell-wall or membrane-related components; however, the number of these targets is limited. In the search for new targets and lead compounds, C. neoformans has been found to be susceptible to mycophenolic acid through its target inosine monophosphate dehydrogenase (IMPDH); in contrast, a rare subtype of the related C. gattii is naturally resistant. Here, the expression, purification, crystallization and preliminary crystallographic analysis of IMPDH complexed with IMP and NAD+ is reported for both of these Cryptococcus species. The crystals of IMPDH from both sources had the symmetry of the tetragonal space group I422 and diffracted to a resolution of 2.5,Å for C. neoformans and 2.6,Å for C. gattii. [source] Capsule enlargement in Cryptococcus neoformans confers resistance to oxidative stress suggesting a mechanism for intracellular survivalCELLULAR MICROBIOLOGY, Issue 10 2008Oscar Zaragoza Summary Cryptococcus neoformans is a facultative intracellular pathogen. The most distinctive feature of C. neoformans is a polysaccharide capsule that enlarges depending on environmental stimuli. The mechanism by which C. neoformans avoids killing during phagocytosis is unknown. We hypothesized that capsule growth conferred resistance to microbicidal molecules produced by the host during infection, particularly during phagocytosis. We observed that capsule enlargement conferred resistance to reactive oxygen species produced by H2O2 that was not associated with a higher catalase activity, suggesting a new function for the capsule as a scavenger of reactive oxidative intermediates. Soluble capsular polysaccharide protected C. neoformans and Saccharomyces cerevisiae from killing by H2O2. Acapsular mutants had higher susceptibility to free radicals. Capsular polysaccharide acted as an antioxidant in the nitroblue tetrazolium (NBT) reduction coupled to ,-nicotinamide adenine dinucleotide (NADH)/phenazine methosulfate (PMS) assay. Capsule enlargement conferred resistance to antimicrobial peptides and the antifungal drug Amphotericin B. Interestingly, the capsule had no effect on susceptibility to azoles and increased susceptibility to fluconazole. Capsule enlargement reduced phagocytosis by environmental predators, although we also noticed that in this system, starvation of C. neoformans cells produced resistance to phagocytosis. Our results suggest that capsular enlargement is a mechanism that enhances C. neoformans survival when ingested by phagocytic cells. [source] Invasion of Cryptococcus neoformans into human brain microvascular endothelial cells requires protein kinase C-, activationCELLULAR MICROBIOLOGY, Issue 9 2008Ambrose Jong Summary Pathogenic fungus Cryptococcus neoformans has a predilection for the central nervous system causing devastating meningoencephalitis. Traversal of C. neoformans across the blood,brain barrier (BBB) is a crucial step in the pathogenesis of C. neoformans. Our previous studies have shown that the CPS1 gene is required for C. neoformans adherence to the surface protein CD44 of human brain microvascular endothelial cells (HBMEC), which constitute the BBB. In this report, we demonstrated that C. neoformans invasion of HBMEC was blocked in the presence of G109203X, a protein kinase C (PKC) inhibitor, and by overexpression of a dominant-negative form of PKC, in HBMEC. During C. neoformans infection, phosphorylation of PKC, was induced and the PKC enzymatic activity was detected in the HBMEC membrane fraction. Our results suggested that the PKC, isoform might play a crucial role during C. neoformans invasion. Immunofluorescence microscopic images showed that induced phospho-PKC, colocalized with ,-actin on the membrane of HBMEC. In addition, cytochalasin D (an F-filament-disrupting agent) inhibited fungus invasion into HBMEC in a dose-dependent manner. Furthermore, blockage of PKC, function attenuated actin filament activity during C. neoformans invasion. These results suggest a significant role of PKC, and downstream actin filament activity during the fungal invasion into HBMEC. [source] Enantioselectivity of inhibition of cytochrome P450 3A4 (CYP3A4) by ketoconazole: Testosterone and methadone as substratesCHIRALITY, Issue 2 2004Shahrzad Dilmaghanian Abstract Racemic ketoconazole (KTZ) was the first orally active azole antifungal agent used in clinical practice and has become widely used in the treatment of mucosal fungal infections associated with AIDS immunosuppression and cancer chemotherapy. However, the use of KTZ has been limited because of adverse drug,drug interactions. KTZ blocks ergosterol biosynthesis by inhibiting the fungal cytochrome P450 (CYP51). KTZ is also a potent inhibitor of human cytochrome P450 3A4 (CYP3A4) enzyme, the major drug-metabolizing CYP isozyme in the human liver. We examined the enantioselective differences of KTZ in the inhibition of human CYP3A4 and in antifungal action. Dextro - and levo -KTZ exhibited modest enantioselective differences with respect to CYP3A4 inhibition of testosterone and methadone metabolism. For both substrates levo -KTZ was approximately a 2-fold more potent inhibitor. We examined the enantioselective differences in the in vitro activity of KTZ against medically relevant species of Candida and Aspergillus, as well as Cryptococcus neoformans. Overall, levo -KTZ was 2,4-fold more active than dextro -KTZ. Therefore, levo -KTZ is a more potent inhibitor of CYP3A4 and has stronger in vitro antifungal activity. Chirality 16:79,85, 2004. © 2004 Wiley-Liss, Inc. [source] | ||||||||||||||||