Biomedical subjects

Juneann W Murphy

Publications and source records attributed to Juneann W Murphy.

8 recordsLinked to original sources

PubMed2005

Levels of L-selectin (CD62L) on human leukocytes in disseminated cryptococcosis with and without associated HIV-1 infection.

Patients with disseminated cryptococcosis typically have measurable levels of cryptococcal polysaccharide in serum samples but minimal leukocyte infiltration into infected tissues. In vitro data have shown that cryptococcal polysaccharide induces L-selectin (CD62L) shedding from leukocytes. To assess shedding in vivo, we compared leukocyte L-selectin levels in human immunodeficiency virus (HIV) type 1-negative and -positive subjects with and without circulating cryptococcal polysaccharide. Results showed that subjects with cryptococcal polysaccharide in serum samples have significantly lower percentages of neutrophils, monocytes, and CD3+ T cells with L-selectin on their surfaces than do healthy subjects, regardless of HIV status. There was significantly more soluble L-selectin in serum samples from subjects with cryptococcosis than in those from uninfected subjects. Reduced L-selectin levels on leukocytes in subjects with circulating cryptococcal polysaccharide and increased serum levels of soluble L-selectin indicates that surface L-selectin shedding is a mechanism that likely explains reduced leukocyte extravasation into infected tissues of patients with disseminated cryptococcosis.

Adult↗

PubMed2004

Introns and splicing elements of five diverse fungi.

Genomic sequences and expressed sequence tag data for a diverse group of fungi (Saccharomyces cerevisiae, Schizosaccharomyces pombe, Aspergillus nidulans, Neurospora crassa, and Cryptococcus neoformans) provided the opportunity to accurately characterize conserved intronic elements. An examination of large intron data sets revealed that fungal introns in general are short, that 98% or more of them belong to the canonical splice site (ss) class (5'GU...AG3'), and that they have polypyrimidine tracts predominantly in the region between the 5' ss and the branch point. Information content is high in the 5' ss, branch site, and 3' ss regions of the introns but low in the exon regions adjacent to the introns in the fungi examined. The two yeasts have broader intron length ranges and correspondingly higher intron information content than the other fungi. Generally, as intron length increases in the fungi, so does intron information content. Homologs of U2AF spliceosomal proteins were found in all species except for S. cerevisiae, suggesting a nonconventional role for U2AF in the absence of canonical polypyrimidine tracts in the majority of introns. Our observations imply that splicing in fungi may be different from that in vertebrates and may require additional proteins that interact with polypyrimidine tracts upstream of the branch point. Theoretical protein homologs for Nam8p and TIA-1, two proteins that require U-rich regions upstream of the branch point to function, were found. There appear to be sufficient differences between S. cerevisiae and S. pombe introns and the introns of two filamentous members of the Ascomycota and one member of the Basidiomycota to warrant the development of new model organisms for studying the splicing mechanisms of fungi.

Aspergillus nidulans↗

PubMed2004

Age-related resistance of C57BL/6 mice to Cryptococcus neoformans is dependent on maturation of NKT cells.

Conflicting results have been reported regarding the ability of C57BL/6 mice to clear infections due to Cryptococcus neoformans. Examination of the various experimental protocols used suggested that C57BL/6 mice might develop the ability to resist infection as they mature. We analyzed the ability of C57BL/6 mice of different ages to respond to immunization with cryptococcal antigen or to clear a cryptococcal infection. Mice were immunized with a soluble cryptococcal culture filtrate antigen (CneF) emulsified in complete Freund's adjuvant (CneF-CFA). Delayed-type hypersensitivity (DTH) reactions elicited by the immunization were significantly stronger in 15-week-old C57BL/6 mice than in 7-week-old mice. Analysis of cryptococcal CFU 8 weeks following intratracheal infection of 7-week-old mice or 15-week-old mice revealed a relative inability of the younger animals to control the infection. Six-week-old immunized and infected mice cleared cryptococci from brain, spleen, and liver in a manner similar to that of immunized and infected 15-week-old mice. However, the older mice cleared cryptococci much more efficiently from the lungs. The possible role for NKT cells was determined by passive transfer of thymocytes from 10-week-old mice (containing mature NKT cells) or 2-week-old mice (containing immature NKT cells) to 6-week-old mice. The 10-week-old thymocytes significantly enhanced the ability of the mice to develop a DTH response after immunization with CneF-CFA, while animals treated with 2-week-old thymocytes did not improve their DTH response after immunization. The cells in the 10-week-old thymocyte population responsible for improvement of DTH responses were identified as being NK1.1 positive.

Aging↗

PubMed2003

FELINES: a utility for extracting and examining EST-defined introns and exons.

FELINES (Finding and Examining Lots of Intron 'N' Exon Sequences) is a utility written to automate construction and analysis of high quality intron and exon sequence databases produced from EST (expressed sequence tag) to genomic sequence alignments. We demonstrated the various programs of the FELINES utility by creating intron and exon sequence databases for the fungal organism Schizosaccharomyces pombe from alignments of EST to genomic sequences. In addition, we analyzed our constructed S.pombe sequence databases and the well-established Saccharomyces cerevisiae intron database from Manuel Ares' Laboratory for conserved sequence motifs. FELINES was shown to be useful for characterizing branchsites, polypyrimidine tracts and 5' and 3' splice sites in the intron databases and exonic splicing enhancers (ESEs) in S.pombe exons. FELINES is available at http://www.genome.ou.edu/informatics.html.

Base Sequence↗

PubMed2003

Role of interleukin-4 in resistance to Cryptococcus neoformans infection.

The role of interleukin (IL)-4 in cryptococcal disease was studied in IL-4 knockout (IL-4KO) and wild-type (WT) mice infected with Cryptococcus neoformans isolates that vary widely in their virulence. Delayed-type hypersensitivity responses were reduced in IL-4KO mice following primary infection with either isolate. Splenic T helper 1 (Th1) cytokine responses were increased in the IL-4KO mice infected with the weakly virulent isolate (184A) but did not change during infection with the highly virulent isolate (NU-2). Th2 cytokine responses (IL-5, IL-10) were downregulated in the IL-4KO mice infected with either isolate. Survival after primary infection with either isolate was not influenced by the absence of IL-4. Fewer colony-forming units were found in the lungs of 184A-infected, IL-4KO mice as compared to WT mice, suggesting that some immunity had developed. IL-4KO mice, primed with small doses of cryptococcal antigen (CneF), had significantly enhanced delayed-type hypersensitivity responses after intravenous infection with 184A and were more resistant to infection compared with WT mice. Increased expression of IL-5 with decreased interferon-gamma contributed to the inability of primed WT mice to resist infection with 184A. Enhanced immunity in the primed IL-4KO mice was reflected in a more moderate increase in IL-5 and IL-10 with maintenance of interferon-gamma levels.

Animals↗

PubMed2003

Effects of tumor necrosis factor alpha on dendritic cell accumulation in lymph nodes draining the immunization site and the impact on the anticryptococcal cell-mediated immune response.

Cell-mediated immune (CMI) responses and tumor necrosis factor alpha (TNF-alpha) have been shown to be essential in acquired protection against Cryptococcus neoformans. Induction of a protective anticryptococcal CMI response includes increases in dendritic cells (DC) and activated CD4(+) T cells in draining lymph nodes (DLN). During the expression phase, activated CD4(+) T cells accumulate at a peripheral site where cryptococcal antigen is injected, resulting in a classical delayed-type hypersensitivity (DTH) reaction. Induction of a nonprotective anticryptococcal CMI response results in no significant increases in the numbers of DC or activated CD4(+) T cells in DLN. This study focuses on examining the role of TNF-alpha in induction of protective and nonprotective anticryptococcal CMI responses. We found that neutralization of TNF-alpha at the time of immunization with the protective immunogen (i) reduces the numbers of Langerhans cells, myeloid and lymphoid DC, and activated CD4(+) T cells in DLN and (ii) diminishes the total numbers of cells, the numbers of activated CD4(+) T cells, and amount of gamma interferon at the DTH reaction site. Although TNF-alpha neutralization during induction of the nonprotective CMI response had little effect on cellular and cytokine parameters measured, it did cause a reduction in footpad swelling when mice received challenge in the footpad. Our findings show that TNF-alpha functions during induction of the protective CMI response by influencing the accumulation of all three DC subsets into DLN. Without antigen stimulated DC in DLN, activated CD4(+) T cells are not induced and thus not available for the expression phase of the CMI response.

Animals↗

PubMed2002

Strain-dependent effects of environmental signals on the production of extracellular phospholipase by Cryptococcus neoformans.

Extracellular phospholipase (PL) activities comprising phospholipase B, lysophospholipase and lysophospholipase transacylase have been identified in culture supernatants of Cryptococcus neoformans and contribute to virulence. We found that PL production was optimal after fungal growth at 30 degrees C and secretion at 37 degrees C for all six C. neoformans isolates studied (four C. neoformans var. neoformans and two C. neoformans var. gattii). No increase in PL activity was found in one strain, NU-2, in low iron or tissue culture media, conditions where upregulation of other virulence factors has been reported. The most virulent strains in an intravenous mouse model of infection were best able to produce PL at growth and secretion temperatures of 37 degrees C, in tissue culture media and under assay conditions of pH 7.0.

Buffers↗

PubMed2002

Differences in components at delayed-type hypersensitivity reaction sites in mice immunized with either a protective or a nonprotective immunogen of Cryptococcus neoformans.

Cell-mediated immunity is the major protective mechanism against Cryptococcus neoformans. Delayed swelling reactions, i.e., delayed-type hypersensitivity (DTH), in response to an intradermal injection of specific antigen are used as a means of detecting a cell-mediated immune (CMI) response to the antigen. We have found previously that the presence of an anticryptococcal DTH response in mice is not always indicative of protection against a cryptococcal infection. Using one immunogen that induces a protective anticryptococcal CMI response and one that induces a nonprotective response, we have shown that mice immunized with the protective immunogen undergo a classical DTH response characterized by mononuclear cell and neutrophil infiltrates and the presence of gamma interferon and NO. In contrast, immunization with the nonprotective immunogen results in an influx of primarily neutrophils and production of tumor necrosis factor alpha (TNF-alpha) at the DTH reaction site. Even when the anticryptococcal DTH response was augmented by blocking the down-regulator, CTLA-4 (CD152), on T cells in the mice given the nonprotective immunogen, the main leukocyte population infiltrating the DTH reaction site is the neutrophil. Although TNF-alpha is increased at the DTH reaction site in mice immunized with the nonprotective immunogen, it is unlikely that TNF-alpha activates the neutrophils, because the density of TNF receptors on the neutrophils is reduced below control levels. Uncoupling of DTH reactivity and protection has been demonstrated in other infectious-disease models; however, the mechanisms differ from our model. These findings stress the importance of defining the cascade of events occurring in response to various immunogens and establishing the relationships between protection and DTH reactions.

Animals↗