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C Steininger

Publications and source records attributed to C Steininger.

5 recordsLinked to original sources
PubMed2002

Comparison of virtual phenotype and HIV-SEQ program (Stanford) interpretation for predicting drug resistance of HIV strains.

OBJECTIVE: Drug resistant HIV strains can be identified by genotypic analysis. The prediction of resistance from the HIV pol sequence, however, requires expert interpretation which is currently provided by various interpretation programs. In the present study, the comparability of two of these programs was investigated. METHODS: One hundred and six HIV sequences obtained from patient samples were subjected to interpretation by the Stanford HIV-SEQ program (http://hivdb.stanford.edu) and, in parallel, by virtual phenotype analysis (VircoNET). RESULTS: The overall concordance between the two assays was high with respect to nonnucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors. Highly discrepant results were obtained from 22 samples (1.5% of all comparisons), and these discrepancies were significantly associated with the interpretation of nucleoside reverse transcriptase inhibitors (NRTIs) (P < 0.01), especially regarding resistance to zalcitabine (ddC), didanosine (ddI) and abacavir (ABC). Nearly all of these discrepant samples showed a sensitive virtual phenotype. Mutations at codons 69 and 74 were associated with a discrepant interpretation for ddC. CONCLUSIONS: The prediction of resistance to certain NRTIs from a given HIV sequence may be contradictory and requires further investigation.

Anti-HIV Agents↗
PubMed2001

Early detection of acute rhinovirus infections by a rapid reverse transcription-PCR assay.

The development of a rhinovirus (RV)-RNA-specific reverse transcription (RT)-PCR assay is complicated by the close homology between the RV and enterovirus (EV) genomes in the highly conserved 5'-noncoding region, which is chosen for primer design in most RT-PCR assays. We have developed a sensitive, rapid, and RV-specific nested RT-PCR assay and have used it to test nasopharyngeal aspirates from 556 patients presenting with acute respiratory tract infections. RV RNA was detected by nested RT-PCR not only in all of 52 samples that were RV positive by virus isolation methods but also in 124 of 367 samples that were negative by virus isolation methods and enzyme-linked immunosorbent assay (ELISA). In addition, in 23 of 137 samples that were positive for a different respiratory virus by virus isolation and/or ELISA, RV RNA was detected by RT-PCR. EVs, adenoviruses, respiratory syncytial viruses, coronaviruses, and influenza and parainfluenza viruses, including clinical isolates as well as stock viruses, were not amplified in our RV-specific RT-PCR assay, indicating that this assay was highly specific. The processing time was less than 2 days for the RT-PCR, as opposed to up to 2 weeks for virus isolation. These results indicate that nested RT-PCR is more sensitive than conventional methods for the detection of RV in patients experiencing acute respiratory tract infections and represents the only reliable tool for the early laboratory diagnosis of RV infections. This is especially important in light of new opportunities for therapy currently being developed.

Adolescent↗
PubMed1995

Studies on selectin-carbohydrate interactions.

Recruitment of neutrophils to sites of inflammation is now believed to occur through an initial rolling interaction at the luminal surface of activated endothelium and is mediated by a class of mammalian lectins referred to as the selectins. Selectins recognize carbohydrate determinants on co-receptors. It is generally believed that many selectin molecules must bind to many carbohydrate receptor molecules i.e. multivalent binding, to enable sufficient binding strength to elicit the rolling response between the neutrophil and the endothelial cell. One of the approaches to the generation of more potent molecular antagonists of the selectin-mediated cell-cell interaction is to mimic the multivalent interaction in a single compound. Recent experiments utilising conjugated forms of sialyl Lewisx-BSA have explored this feasibility (Welply et al., 1994). In that study, monovalent sLex (sialic acid alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc), the minimum binding determinant for E-selectin, as well as monovalent sialyllactosamine (sialic acid alpha 2-3Gal beta 1-4GlcNAc), a non-binding structure, and the corresponding multivalent BSA-conjugated forms were tested for their ability to inhibit binding of HL-60 cells to immobilised E-selectin. As expected, only sLex and sLex-BSA were found to do so. sLex16-BSA (16 mol tetrasaccharide/mol BSA) showed a dose-dependent inhibition of HL-60 binding with a measured IC50 of 1 microM; demonstrating close to a three-order of magnitude enhancement of inhibitory activity compared to free sLex. This result indicated that multivalent forms of sLex are capable of binding to E-selectin with higher affinity than do monovalent glycans. In another study, fluorescent forms of monovalent sLex were synthesized and used to measure a true thermodynamic dissociation constant for the monovalent sLex:E-selectin interaction of 120 +/- 31 microM (Jacob et.al., 1995).

Animals↗
PubMed1994

Multivalent sialyl-LeX: potent inhibitors of E-selectin-mediated cell adhesion; reagent for staining activated endothelial cells.

Free, monovalent, SLeX (Neu5Ac alpha 2-3Gal beta 1-4(Fuc alpha 1-3)-GlcNAc), SLn (Neu5Ac alpha 2-3Gal beta 1-4GlcNAc) and corresponding BSA-conjugated forms--displaying different ratios of SLeX and SLn to protein--were tested for their ability to inhibit binding of HL-60 cells to immobilized E-selectin. Free SLeX and conjugated SLeX-BSA inhibited cell binding in a dose-dependent manner. SLn and SLn-BSA did not inhibit binding. SLeX16BSA (16 mol tetrasaccharide/mol BSA) and monovalent SLeX inhibited cell binding with measured inhibitory concentrations (IC50S) of 1 microM and 1 mM, respectively, demonstrating a three-order-of-magnitude enhancement of inhibitory activity with the multivalent form of SLeX. A SLex7BSA conjugate was 10-fold less potent than those with 11 or 16 mol SLeX/mol BSA. An assay which measured neutrophil rolling on interleukin (IL)-1 beta-activated human umbilical vein endothelial cells (HUVECs) showed 50% reduction in the number of rolling neutrophils in the presence of 1 microM SLeX16BSA, whereas the level of free, monovalent SLeX oligosaccharide required to produce the same effect was approximately 0.3 mM. SLeX-BSA was found to be an excellent reagent for staining endothelial cells expressing E-selectin. Biotinylated SLeX-BSA in conjunction with Texas red avidin-stained lipopolysaccharide (LPS)-activated HUVECs, and co-incubation of activated cells with anti-E-selectin, specifically blocked staining. The distribution of E-selectin, as determined by binding of SLeX-BSA, was virtually identical with that obtained by binding of anti-E-selectin antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Adhesion↗