Gene/Protein Disease Symptom Drug Enzyme Compound
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The areA gene of Aspergillus nidulans is a positive-acting transcriptional factor required for the expression of genes involved in the utilization of a broad range of nitrogen sources other than ammonium and glutamine. We have investigated the role in pathogenesis of the corresponding gene (AfareA) of Aspergillus fumigatus, a causative agent of invasive pulmonary aspergillosis. Stable and unstable AfareA- strains were constructed and tested for altered virulence in mice on the basis of host survival, mixed infection experiments and genetic reversion studies. These showed that the AfareA gene contributes to, but is not essential for, virulence. Strains carrying extragenic mutations that partially suppress the AfareA- phenotype for growth on different nitrogen sources were tested for altered virulence in mixed infection studies. One of these was found to be more virulent than the parental AfareA- strain.
Mol Gen Genet 1998 Jun
PMID:The role of the Aspergillus fumigatus areA gene in invasive pulmonary aspergillosis. 966 38

Invasive pulmonary aspergillosis in immunocompromised patients (ICP) is the second most frequent opportunistic fungal infection. The causative organism includes 16 species of Aspergillus, of which A. fumigatus dominates the ubiquitous incidence of invasive or allergic broncho-pulmonary aspergillosis (ABPA). The definitive diagnosis of invasive aspergillosis is difficult. We have analyzed 24 strains of A. fumigatus recovered from ICP using the RAPD technique. The profiles generated with the 20 primers tested were mostly unique. These results may have a profound impact on the management of aspergillosis, especially in the ICP.
Biochem Mol Biol Int 1998 Oct
PMID:Aspergillus fumigatus strains recovered from immunocompromised patients (ICP): subtyping of strains by RAPD analysis. 981 93

The cytologic diagnosis of pulmonary aspergillosis infection is typically made on a presumptive basis and later confirmed by fungal culture, which may take up to one week to complete. An in situ hybridization (ISH) probe specific for Aspergillus for use in surgical pathology specimens has been developed which has not been used on cytology preparations. We describe a supra-threshold adapted testing (STAT) in situ hybridization test for cytology specimens, which takes less than one hour to finish. We performed ISH on three cases of culture-proven pulmonary aspergillosis and one case with Aspergillus fungal forms but negative cultures to test the feasibility of using this same Aspergillus probe on cytology specimens. Four patients with pulmonary aspergillosis were initially diagnosed by cytologic examination of their respective specimens. The presumptive diagnosis was confirmed by culture to be Aspergillus fumigatus on three cases. ISH on both cytology cytospin and Thin-Prep specimens was performed using an rRNA Aspergillus specific probe. All four cytology specimens exhibited positive staining with the Aspergillus probe. Most, but not all, fungal hyphae were stained with the probe. Even though ISH is more expensive than culture, in situ hybridization can be performed in less than one hour on cytology specimens and may be beneficial for patients in selected clinical circumstances.
Int J Mol Med 2000 Apr
PMID:Ultra fast identification of Aspergillus species in pulmonary cytology specimens by in situ hybridization. 1071 62

Signature-tagged mutagenesis (STM) is a method that has been used to screen for genes required for in vivo survival of pathogenic bacteria, but has not been used to investigate a eukaryotic pathogen in an animal model of disease. We have adapted STM to identify genes required for in vivo growth of the opportunistic fungal pathogen Aspergillus fumigatus. Using a mouse model of invasive pulmonary aspergillosis, we have isolated several mutant strains with defects in their ability to replicate in vivo. One strain unable to cause lethal infection was further characterized and found to have an insertion into the promoter of a gene (pabaA) encoding para-aminobenzoic acid synthetase, an enzyme catalyzing a late step in the biosynthesis of folate. The complete inability of this strain, and other pabaA- strains constructed in this study by targeted gene deletion, to cause lethal infection in mice confirms the importance of the folate synthesis pathway for in vivo survival of this pathogen. The successful application of STM to A. fumigatus demonstrates that in vivo genetic analysis of eukaryotic pathogens is feasible and could result in the identification of potential targets, such as para-aminobenzoic acid synthetase, for novel antifungal therapies.
Mol Microbiol 2000 Jun
PMID:Signature-tagged and directed mutagenesis identify PABA synthetase as essential for Aspergillus fumigatus pathogenicity. 1093 Dec 87

Invasive fungal infections (IFI) parallel the explosive increase in the immunocompromized patient population, and are characterized by diagnostic difficulties and extreme mortality. Candidemia in a tertiary referral hospital in the Middle East confirms the current epidemiologic shift in this common blood stream pathogen towards non-malignancy cases (38%) and antifungal prophylaxis failure (20%), high presentation sepsis scores and attributable mortality (32%). Invasive aspergillosis (IA) is also associated with high mortality. Use of non-invasive computerized tomographic (CT) radiologic scanning linked to early administration of high dose liposomal amphotericin B (LAB) is associated with a reduced mortality of 9.5% compared to historical experience of 28%.Life threatening invasive aspergillosis also occurs in patients who are less obviously immunocompromized. Investigations may reveal subtle immune deficits which could place the patient at some risk for an invasive mycosis. Antifungal treatment used in combination with progenitor cell growth factors and gamma-interferon has proved successful in such situations of progressive fungal disease unresponsive to antifungal therapy alone. Pharmacologic remodeling of existing compounds by lipidisation reduces both the toxicity denominator and the efficacy numerator of the therapeutic index when compared to the parent drug. A comparative dose study of liposomal amphotericin B in aspergillosis has demonstrated equi-efficacy, generated debate over the ability of the controlled clinical trial to be capable of assessing antifungal efficacy, and illustrated that recovery from an invasive fungal infection may require maximum tolerated doses and immunomanipulation. Several new antifungal strategies are under clinical investigation. These include reformulating existing antifungals, exploitation of the growing knowledge of virulence factors to synthesize antagonists, immune reconstitution and immunoprotection. An interim analysis of an ongoing placebo controlled study of recombinant interleukin-11 to assess its efficacy in reducing sepsis in leukemia patients through prevention of chemotherapy induced gut epithelial cell apoptosis, has demonstrated a difference in the two study arms in sepsis rates and preservation of gastrointestinal epithelial cell integrity. The unique and special challenges presented by the dynamic epidemiologics of invasive fungal infections are demanding and attracting considerable responses, in the fields of diagnosis and therapeutics. Current strategies need considerable improvement, yet ongoing collaborative efforts will have a positive impact on our understanding of the fungus-host interaction and ultimately our ability to offer better care for our patients with invasive mycoses.
Mol Immunol 2002 May
PMID:Invasive fungal infections: evolving challenges for diagnosis and therapeutics. 1200 73

We reviewed 43 adult kidney transplant patients (32 males and 11 females, 14-68 years of age) performed at our center between July 1999 and February 2002. Donors (39 males and 4 females) comprised two cadaverics, five living-related and 36 living-unrelated; age 18-44 years. Indications for kidney transplantation (KT) were: chronic glomerulonephritis (8), re-transplantation (4) and chronic pyelonephritis (3); kidney disease was unknown in 15 cases. ATG-F was given as a single intra-operative bolus induction therapy in 26 patients; extended ATG-F dose was given in 17 patients because of a high sensitization status, slow graft function (SGF) or development of calcineurin inhibitors toxicity. ATG-F was stopped in seven out of 17 patients because of thrombocytopenia or severe anemia. ATG-F-related fever occurred in six patients. Acute rejection (AR) occurred in eight patients (18%) 5-11 days post-KT. ATG-F was given in three steroid-resistant AR. Infection occurred in 19 patients (44%) for a total of 32 infectious episodes comprising 24 bacterial infections (nine urinary, seven catheter-related and three respiratory), six viral infections (five CMV and one herpes) and two fungal infections (one pulmonary aspergillosis and one catheter-related candidiasis). The hospital stay was 8-75 days for a median of 13 days. The mean serum creatinine upon discharge, at 1 and 6 months after KT were: 2.04+/-0.37, 1.43+/-0.16 and 1.29+/-0.08, respectively. One patient lost his graft on day 9 because of graft microthrombi related to Factor V-Leiden mutation. The 6 months actuarial patient and graft survival were 100 and 97.6%, respectively. ATG-F as a bolus therapy is an effective and safe induction treatment in KT.
Mol Immunol 2003 Jul
PMID:Intraoperative anti-thymocyte globulin-Fresenius (ATG-F) administration as induction immunosuppressive therapy in kidney transplantation. 1283 82

Asp fI is a major allergen/antigen/cytotoxin of Aspergillus fumigatus and exhibits ribonuclease activity. This allergen plays a role in allergic and invasive Aspergillosis and reported as a major cytotoxin with ribonuclease activity. To express the protein in large quantity and to characterize the multifunctional nature of Asp fI, we have generated recombinant baculovirus by introducing the gene in pFastBac HTa expression vector and expressed in insect cell. The baculovirus expression vector system has been used as a versatile system for the efficient expression of proteins with most eukaryotic posttranslational modification. Recombinant Asp fI was expressed as approximately 1% of the total cellular protein in infected Sf9 insect cells. The protein was purified using Ni2+ affinity column chromatography and the yield of purified protein was approximately 10 mg/l g of total cellular protein. Immunoreactivity of the protein was determined by immunoblot analysis using both poly His monoclonal antibody, IgG and IgE antibodies present in the sera of ABPA patients. The protein was glycosylated as revealed by the glycoprotein staining and was observed to retain both ribonuclease and cytotoxic activities. These results suggest that Asp fI expressed in insect cell was post translationally modified and biologically active that can be used as a diagnostic marker for biochemical studies.
Mol Cell Biochem 2003 Oct
PMID:Expression and characterization of Asp fI, an immunodominant allergen/antigen of A. fumigatus in insect cell. 1457 89

We have cloned and characterized the Aspergillus fumigatus cpcA gene encoding the transcriptional activator of the cross-pathway control system of amino acid biosynthesis. cpcA encodes a functional orthologue of Saccharomyces cerevisiae Gcn4p. The coding sequence of the 2.2 kb transcript is preceded by two short upstream open reading frames, the larger one being well conserved among Aspergilli. Deletion strains in which either the coding sequence or the entire locus are replaced by a bifunctional dominant marker are impaired in their cross-pathway control response upon amino acid starvation, as demonstrated by analyses of selected reporter genes and specific enzymatic activities. In a murine model of pulmonary aspergillosis, cpcAdelta strains display attenuated virulence. Pathogenicity is restored to wild-type levels in strains with reconstitution of the genomic locus. Competitive mixed infection experiments additionally demonstrate that cpcAdelta strains are less able to survive in vivo than their wild-type progenitor. Our data suggest that specific stress conditions are encountered by A. fumigatus within the mammalian host and that the fungal cross-pathway control system plays a significant role in pulmonary aspergillosis.
Mol Microbiol 2004 May
PMID:The Aspergillus fumigatus transcriptional activator CpcA contributes significantly to the virulence of this fungal pathogen. 1510 84

The ability of a pathogen to adapt to the host environment is usually required for the initiation of disease. Here we have investigated the importance of the Aspergillus nidulans PacC-mediated pH response in the pathogenesis of pulmonary aspergillosis. Using mutational analysis, we demonstrate that, in neutropenic mice, elimination of the A. nidulans pH-responsive transcription factor PacC, blocking the ambient pH signal transduction pathway or prevention of PacC proteolytic processing acutely attenuates virulence. Infections caused by these alkali-sensitive mutants are characterized by limited growth in vivo and a reduction of inflammatory cell infiltration. In stark contrast, constitutive activation of PacC causes increased mortality marked by extensive fungal invasive growth. PacC action is therefore required for, and able to enhance virulence, demonstrating that the A. nidulans pH-responsive transcription factor PacC plays a pivotal role in pulmonary pathogenesis.
Mol Microbiol 2005 Feb
PMID:The Aspergillus pH-responsive transcription factor PacC regulates virulence. 1568 55

The growing importance of infectious caused by Aspergillus species during the last decade has created a need for practical and reproducible animal models of invasive aspergillosis suitable for studying fungal virulence, infection pathogenesis, diagnostic markers, and testing of antifungal therapy. Murine models remain the most commonly used models for studying aspergillosis because of their ease of manipulation and the large number of reagents available for studying disease-host responses. This chapter provides describes a murine model of invasive aspergillosis suitable for basic and translational studies of invasive pulmonary aspergillosis and highlights experimental variables that affect the course and reproducibility of infection.
Methods Mol Med 2005
PMID:Murine model of invasive aspergillosis. 1588 39


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