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E Reiss

Publications and source records attributed to E Reiss.

At least 37 records · Page 2Linked to original sources
PubMed1994

Immunochemical analysis of the H and M glycoproteins from Histoplasma capsulatum.

The H and M antigens of Histoplasma capsulatum are glycoproteins, and both possess epitopes found on the C antigen, a cross-reactive galactomannan shared by the major genera of systemic dimorphic fungi. We modified the H and M glycoproteins by chemical and enzymatic digestion to determine the relative contributions of the carbohydrate and protein moieties to the immunological reactivities and the apparent molecular weights of these antigens. Endoglycosidases with known action patterns were used to determine the nature of the glycopeptide bonds in the H and M antigens. The effects of these treatments were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, lectin binding, and enzyme-linked immunoelectrotransfer blots probed with polyclonal and monoclonal antibodies (MAbs). Oxidation with 100 mM periodate destroyed the common fungal epitope recognized by MAb CA1-CB4 and nearly all of the concanavalin A-binding sites on both the H and M antigens; it also caused the molecular mass of the M antigen to shift from 94 to 88 kDa. Treatment of samples with O-glycanase had little, if any, effect on the H and M glycoproteins. On the other hand, treatments with endo-beta-N-acetylglucosaminidase H, and particularly peptide N-glycoproteins F (PNGase F), produced pronounced shifts in the M(r) but did not completely eliminate concanavalin A- or MAb CA1-CB4-binding sites. PNGase F treatment caused the molecular mass of the H antigen to shift from 116 to 94 kDa and that of the M antigen to shift from 94 to 74 kDa. The susceptibilities of the H and M glycoproteins to endo-N-acetyl-beta-D-glucosaminidases suggest that their glycosidic moieties are N linked.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody Specificity↗
PubMed1993

Nucleotide sequence analysis of the 5.8S rDNA and adjacent ITS2 region of Candida albicans and related species.

We have determined the nucleotide sequence for the DNA encoding the 5.8S RNAs and downstream internal transcribed spacer (ITS2) regions for Candida albicans and the taxonomically related species C. parapsilosis, C. tropicalis, C. glabrata and C. krusei. Phylogenetic analysis of all known fungal 5.8S RNA sequences revealed a close relationship between C. tropicalis and C. parapsilosis, and to a lesser extent C. albicans within the yeast-like fungi. This group can itself be delineated from predominantly filamentous species. The more distal relationships between Candida (Torulopsis) glabrata and C. krusei support previous findings based on small (18S) ribosomal RNA sequence analysis, suggesting a greater degree of evolutionary divergence of these species from the C. albicans group. Among strains of C. albicans we observed conservation of the ITS2 region at the nucleotide level. Conservation was also observed for a more limited number of C. parapsilosis strains. Although the 3' region of the ITS spacer was species specific, sequence homology was observed in the 5' end within the albicans/parapsilosis/tropicalis group. Our findings suggest a rapid approach to species identification through the use of non-conserved regions flanked by highly conserved, functional domains.

Base Sequence↗
PubMed1993

Purification and characterization of the extracellular aspartyl proteinase of Candida albicans: removal of extraneous proteins and cell wall mannoprotein and evidence for lack of glycosylation.

Aspartyl proteinase (AP) is an extracellular enzyme of Candida albicans implicated as a pathogenic factor. Previous reports on the purification and characterization of AP suggested that a single DEAE-Sephadex chromatographic step was sufficient for the removal of extraneous proteins and that the final product was glycosylated. We purified AP using a chromatographic series consisting of DEAE-Sephadex A25, Sephadex G75 and rechromatography on DEAE-Sephadex A25. Use of DEAE-Sephadex alone did not remove extraneous proteins and removed little contaminating mannoprotein (MP). The addition of a Sephadex G75 column to the purification scheme removed the majority of contaminating MP and proteins. The final DEAE-Sephadex A25 chromatographic step resulted in (a) removal of detectable extraneous proteins, (b) removal of immunologically detectable MP by dot blot and Western blot enzyme immunoassay, (c) loss of periodic acid-silver stain positivity, and (d) a high AP yield (1295 U l-1) and specific activity (1749 U mg-1). We conclude that a single DEAE-Sephadex A25 purification step is insufficient to remove extraneous proteins and MP, which could interfere with the production of AP-specific antibodies and the dissection of moieties responsible for immune reactivity. Reports of periodic acid-Schiff or anthrone positivity of AP preparations may reflect the presence of extraneous MP, which can be removed by the chromatographic series we describe.

Aspartic Acid Endopeptidases↗
PubMed1993

Nonculture methods for diagnosis of disseminated candidiasis.

Two of the nonculture approaches to the diagnosis of DC, enzymatic-fluorometric determination of serum D-arabinitol and detection of marker antigens in antigenemia (enolase and CWMP), have been commercialized and have shown promise in limited clinical trials. These approaches are not new but are the culmination of efforts made over 10 or more years. Clearly, further fine-tuning of both metabolite and antigen detection is needed to simplify the methods and to improve their sensitivity and specificity so that they will be valuable in guiding clinical treatment decisions. An alternative approach, detection of DC by DNA amplification methods such as PCR, is a special case of a compelling technology and one that is capable of standardization across microbial genera. The availability of simplified PCR diagnostic methods for DC remains a tantalizing prospect. Nevertheless, the development of methods to release DNA from very small numbers of Candida organisms in the blood in a form that is sufficiently free of inhibitors of PCR will require further intensive effort. The maturation of these converging laboratory approaches to nonculture diagnosis of DC leads to more optimism about the eventual use of these methods in clinical laboratories.

Antigens, Fungal↗
PubMed1993

Heterogeneity of the purified extracellular aspartyl proteinase from Candida albicans: characterization with monoclonal antibodies and N-terminal amino acid sequence analysis.

Three dominant proteins (41, 48, and 49 kDa) were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in purified preparations of the extracellular aspartyl proteinase (AP) of Candida albicans. All three proteins bound to the specific carboxyl proteinase ligand, pepstatin A, and were associated with maximum AP activity. The N-terminal amino acid sequence for the 48- and 49-kDa proteins matched that reported by others for AP, whereas the sequence for the 41-kDa protein was unique and was not homologous to any known protein. Time course studies demonstrated the simultaneous presence of all three proteins, supporting evidence that the 41- and 48-kDa proteins were not breakdown products of AP. Previous studies did not detect carbohydrate in SDS-polyacrylamide gels of purified AP preparations stained with periodic acid and silver, making glycosylation an unlikely explanation for the observed differences in the molecular masses of the proteins. Some monoclonal antibodies directed against the 49-kDa protein reacted with the 41- and 48-kDa proteins, indicating cross-reactive epitopes. Other monoclonal antibodies, however, reacted only with the 49-kDa protein. We conclude that three pepstatin A-binding proteins occur in purified AP preparations: two have the same amino acid N terminus as that reported for AP, whereas the third has a unique sequence. All three proteins should be considered when undertaking studies to determine the role of AP in candidal pathogenesis or when preparing specific antibodies for antigen capture assays.

Amino Acid Sequence↗
PubMed1993

Evaluation of cation exchange chromatography for the isolation of M glycoprotein from histoplasmin.

Cation exchange chromatography was evaluated to purify the M antigen from histoplasmin (HMIN). Two H and M antigen-containing fractions, soluble (S) and precipitate (PP), resulted from the initial 0.025 M, pH 3.5 citrate buffer dialysis step. The PP fraction contained 62% of the M antigen activity and was resolubilized. Both fractions were chromatographed on CM Sepharose CL-6B. Polysaccharide C antigen was abundant in the S fraction and most of it did not bind to CM Sepharose. M antigen-enriched fractions were eluted with 0.5 M NaCl. Re-chromatography of the relevant S fraction (S-II) and PP fraction (PP-II) by linear gradient fast protein liquid chromatography (FPLC) removed protein and C impurities. M antigen purified by FPLC from the PP-II fraction was depleted of other antigens when Western blots were probed with anti-M, anti-H and anti-C monoclonal antibodies (Mabs). M antigen was identified as a 94 kDa glycoprotein containing a specific-protein epitope and an epitope that reacted with a Mab against the polysaccharide C antigen. M antigen can be purified from HMIN by tandem cation exchange chromatography of the precipitable fraction on an open CM Sepharose CL-6B column followed by linear gradient FPLC.

Blotting, Western↗
PubMed1992

Structural variability in the glucuronoxylomannan of Cryptococcus neoformans serotype A isolates determined by 13C NMR spectroscopy.

Cryptococcus neoformans, the etiologic agent of cryptococcal meningoencephalitis, produces glucuronoxylomannan (GXM) as the major capsule component. Purified GXMs obtained from eight serotype A isolates of C. neoformans were treated by ultrasonic irradiation and then O-deacetylated prior to their comprehensive chemical analysis by GLC, GLC-MS, and 13C NMR spectroscopy. The average xylose: mannose: glucuronic acid molar ratio of the eight isolates is 1.96 +/- 0.25: 3.00: 0.58 +/- 0.10. Methylation analyses and 13C NMR spectroscopy show a general structure for GXM that is comprised of a linear (1----3)-alpha-D-mannopyranan substituted with beta-D-GlcpA and with beta-D-Xylp at O-2. Variable quantities of unsubstituted (1----3)-alpha-D-Manp were observed between the eight isolates studied. In several isolates some of the (1----3)-alpha-D-Manp residues are disubstituted with beta-D-GlcpA at O-2 and with beta-D-Xylp at O-4; this type of substitution was not previously thought to occur in serotype A isolates. Heterogeneity, between isolates, in the disposition of the substituents along the mannopyranan backbone was revealed by 13C NMR spectroscopy. The eight isolates, and three isolates previously studied, were each assigned to one of four distinct groups based on the 13C NMR chemical shifts of the anomeric carbons. Six of the eleven isolates gave identical spectra (Group I). The six major anomeric resonances from Group I were assigned to specific glycosidic linkages present in GXM. The remaining five isolates gave more complex spectra that are indicative of additional linkages and comprise the remaining three groups. Three of these five isolates contain substantial amounts of linkages previously thought to be distinctive of serotypes B and C, i.e., Manp residues that are 4-O-glycosylated with beta-D-Xylp. Methylation analyses only predicted an average repeating unit, whereas 13C NMR spectroscopy demonstrated that GXM from each isolate may be categorized into four groups by the occurrence of distinct sequences of carbohydrate residues.

Carbohydrate Sequence↗
PubMed1992

Characterization of the Syrian hamster c-Ha-ras gene and intron-D-exon transcript.

The coding sequences as well as 5'- and 3'-flanking sequences of the Syrian hamster c-Ha-ras gene were deduced from cDNA clones derived from embryo fibroblast cell lines. Sequences of introns B, C, and D were obtained from genomic DNA after amplification by the polymerase chain reaction. Sequence comparisons with rat, mouse, and human c-Ha-ras genes revealed a high degree of homology. One of 12 cDNA clones contained intron-D-exon (IDX) sequences due to alternative splicing that would encode a p19 Ha-ras gene product. Conservation between species suggests a functional role for the IDX, possibly as a negative control of p21 Ha-ras expression.

Amino Acid Sequence↗
PubMed1990

Cell-wall glucans of Cryptococcus neoformans Cap 67.

Purified cell walls derived from Cryptococcus neofromans Cap 67, an acapsular mutant, consisted of 86% Glc and 7.3% GlcNAc. The integrity of the cell walls was disrupted in three successive extractions with 60% 4-methylmorpholine N-oxide (4-MMNO) at 120 degrees. Four 4-MMNO-soluble D-glucopyranans were isolated. Released within 0.5 h was water-insoluble Gi-1, followed by two water-soluble Gs fractions and water-insoluble Gi-2 over 17.5 h. A 4-MMNO-insoluble residue, containing 27% of GlcNAc, was also isolated. Gi-1 and Gi-2 were isolated as precipitates during dialysis of 4-MMNO extracts and were each reduced with NaBH4 to permit their investigation in alkaline solution. Gs-1 and Gs-2 were separated by ion-exchange chromatography of the water-soluble fractions. The structures of the D-glucopyranans were determined by 13C-n.m.r. spectroscopy and by g.l.c.-mass spectrometry of their per-O-methylated derivatives. Gi-1 was a (1----3)-alpha-D-glucopyranan (97%) with some (1----4)-D-glucosidic linkages (3%) and no chain-branching. Gs-1 and Gs-2 were (1----6)-beta-D-glucopyranans branched at O-3 (10-12%) with beta-D-Glcp-(1----3)-beta-D-Glcp side chains. Gs-2 may have approximately 2% more chain branching than Gs-1. Gi-2 was a D-glucopyranan with 80% of its structure like that of Gi-1, and 20% like that of Gs-1 and -2; the water-insolubility of Gi-2 suggests that these structures were covalently linked. Almost identical D-glucopyranans were obtained from aged cultures that had thickened walls (as observed by electron microscopy).

Cell Wall↗
PubMed1990

Activation of cellular oncogenes by chemical carcinogens in Syrian hamster embryo fibroblasts.

Carcinogen-induced point mutations resulting in activation of ras oncogenes have been demonstrated in various experimental systems such as skin carcinogenesis, mammary, and liver carcinogenesis. In many cases, the data support the conclusion that these point mutations are critical changes in the initiation of these tumors. The Syrian hamster embryo (SHE) cell transformation model system has been widely used to study the multistep process of chemically induced neoplastic transformation. Recent data suggest that activation of the Ha-ras gene via point mutation is one of the crucial events in the transformation of these cells. We have now cloned the c-Ha-ras proto-oncogene from SHE cDNA-libraries, and we have performed polymerase chain reaction and direct sequencing to analyze tumor cell lines induced by different chemical carcinogens for the presence of point mutations. No changes were detectable at codons 12, 13, 59, 61, and 117 or adjacent regions in tumor cell lines induced by diethylstilbestrol, asbestos, benzo(a)pyrene, trenbolone, or aflatoxin B1. Thus, it is not known whether point mutations in the Ha-ras proto-oncogene are essential for the acquisition of the neoplastic phenotype of SHE cells. Activation of other oncogenes or inactivation of tumor suppressor genes may be responsible for the neoplastic progression of these cells. However, in SHE cells neoplastically transformed by diethylstilbestrol or trenbolone, a significant elevation of the c-Ha-ras expression was observed. Enhanced expression of c-myc was detected in SHE cells transformed by benzo(a)pyrene or trenbolone.

Animals↗
PubMed1989

Immunoelectronmicroscopic characterization of monoclonal antibodies (MAbs) against Cryptococcus neoformans.

Three monoclonal antibodies (MAbs) (BA4, BD1, CD6) reacted with Cryptococcus neoformans capsular glucuronoxylomannan (GXM) polysaccharide showing distinctive patterns against four serotypes as revealed by enzyme immunoassay (EIA), dot EIA, and immunofluorescence. Immunoelectron microscopy (IEM) was used to characterize binding sites for the MAbs on the C. neoformans capsule. All three MAbs bound to the capsule of serotype A strains 9104 and 9759. Differences in the intensity of binding to the two serotype A strains could not be explained by capsule diameter. The MAb BA-4 IgM bound well to 9759 (large capsule) and poorly to 9104 (small capsule), whereas MAb BD-1 (IgG-1) bound well to strain 9104 and poorly to strain 9759. Spurr's embedment inactivated the BA-4-binding epitopes in the C. neoformans 9759 capsule, but did not inactivate the ones that bound to BD-1. The epitopes recognized by BA-4 were different than the BD-1-binding determinants. The MAb CD-6 bound to a cytoplasmic precursor of capsular GXM. CD-6 (IgG) stained the capsule, cell wall, and cytoplasm of both C. neoformans tester strains. Competitive binding experiments were conducted. Single immunogold labelling showed that BD-1 inhibited the binding of BA-4, but not vice versa. The interaction between CD-6 and BA-4 resulted in a reciprocal inhibition. Double-labelling experiments showed reciprocal inhibition between BA-4 and each of the IgG MAbs. These MAbs are directed against capsular polysaccharide or its intracellular precursor. None of the MAbs stained C. neoformans cap 67, an acapsular mutant that does not contain GXM.

Antibodies, Fungal↗
PubMed1989

Characterization of Cryptococcus neoformans capsular glucuronoxylomannan polysaccharide with monoclonal antibodies.

Mice were immunized with Cryptococcus neoformans serotype A capsular glucuronoxylomannan (GXM) conjugated to bovine serum albumin-adipic dihydrazide. Two splenocyte fusions yielded two monoclonal antibodies (MAbs) that were highly reactive in dot enzyme immunoassay, immunofluorescence, and sandwich enzyme immunoassay. The first MAb, BD-1 [immunoglobulin G1 (kappa) [IgG1(kappa)]], was GXM-A and GXM-D specific, whereas the second MAb, BA-4 (IgM), reacted with GXM-A and GXM-B. A third MAb, CD-6 [IgG1(kappa)], originated from mice immunized with O-deacetylated GXM-C-bovine serum albumin and reacted with GXMs of all four serotypes. Two of the MAbs (CD-6 and BD-1) were further characterized with chemically modified GXMs. Removal of glucuronosyl residues completely inhibited the binding of both MAbs, implicating (1----2)-beta-glucuronic acid as a key component of the epitope. Removal of (1----2)-beta-xylosyl residues decreased reactivity to an intermediate extent. O deacetylation led to a measurable decrease but had the least inhibitory effect of the three GXM derivatives tested. The combining site for these two MAbs appears to be a complex antigenic determinant involving more than one glycosidic residue.

Antibodies, Fungal↗
PubMed1989

Genetic differences between type I and type II Candida stellatoidea.

Genetic similarities and differences between type I and type II Candida stellatoidea were studied. The electrophoretic karyotype, mitochondrial DNA (mtDNA) restriction patterns, and midrepeat sequence of nuclear DNA in type I C. stellatoidea were clearly distinguishable from those of a reference culture of Candida albicans. The karyotype and the major bands of the midrepeat sequence of type II C. stellatoidea were indistinguishable from those of the reference C. albicans. The mtDNA restriction patterns of four type I isolates were homogeneous regardless of the endonucleases and probes used. The mtDNA restriction patterns of type II C. stellatoidea varied from strain to strain. Some of them were identical to that of C. albicans, while others were the same as that of type I C. stellatoidea. Immunofluorescence with C. albicans serotype A-specific monoclonal antibody indicated that the four isolates of type I C. stellatoidea were serotype B (non-A), whereas all three type II isolates studied were serotype A. Taken together, these results support the hypothesis that the isolates of C. stellatoidea type II studied are sucrose-negative mutants of serotype A C. albicans. Since C. stellatoidea type I differs from C. albicans in several major genetic characteristics, it cannot be viewed as a simple mutant derived from C. albicans. Hybrids produced by protoplast fusion of type I and type II cells were capable of assimilating sucrose, indicating that the sucrose-negative phenotypes of the parents are due to different mutations.

Candida↗
PubMed1988

Structure determination of Cryptococcus neoformans serotype A-variant glucuronoxylomannan by 13C-n.m.r. spectroscopy.

A series of polysaccharides was derived by physical and chemical methods from an antigenic, O-acetyl-containing, glucuronoxylomannan (GXM), isolated from the growth medium of Cryptococcus neoformans (CDC B2550) serotype A-variant having composition ratios of Man:Xyl:GlcA:OAc = 10:4:3:6. 13C-N.m.r. spectra of derivatives provided new structural evidence for GXM. Treatment of GXM with Li in ethylenediamine gave a xylomannan (XM, with Man:Xyl = 5:2). Smith degradation of XM gave a mannan (M). Ultrasonic treatment of GXM gave GXM-sonicated (GXMS). Treatment of GXM with 3-(3-dimethylaminopropyl)-1-ethylcarbodiimide.HCl and then with NaBH4 gave reduced GXMS (RGXMS), or with aq. trifluoroacetic acid gave partially acid-hydrolyzed GXMS. Periodate oxidation of GXM and NaBH4 reduction of the product gave a polyalcohol-mannan (PM). Treatment of GXMS, RGXMS, and PM with NH4OH at pH 11 gave the respective O-deacetylated analogs. Comparison among the 13C-n.m.r. spectra of GXM, the various derivatives, and reference monosaccharides allowed the following conclusions: M is (1----3)-alpha-D-mannopyranan; XM consists of the M backbone with 91% of the Xyl on nonadjacent Man residues as 2-O-beta-D-Xylp substituents and with 9% as 4-O-D-Xylp substituents on other Man residues. GXM consists of the XM structure, but with non-D-xylosylated Man residues substituted with 2-O-beta-D-GlcpA substituents and with 6-O-acetyl groups distributed approximately equally on Man residues that have other substituents and those that have none. The molecular mechanics program MM2 was used to estimate the relative energies of anomeric orientations of the typical glycosidic linkage in M. The results suggest that 6'-OH----O-2 H-bonding is significant in the minimal-energy orientation of M, with phi = -36 degrees and psi = 51 degrees, and that two other glycosidic orientations may be important in the 2-O- or 6-O-substituted derivatives of M.

Cryptococcus↗