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Biomedical subjects

J A Waitz

Publications and source records attributed to J A Waitz.

At least 19 recordsLinked to original sources
PubMed1989

Antigen specific and MHC nonrestricted cytotoxicity of T cell receptor alpha beta+ and gamma delta+ human T cell clones isolated in IL-4.

IL-4 has been shown to act as a growth factor for human T cells. In addition, IL-4 can enhance CTL activity in MLC, but blocks IL-2 induced lymphokine activated killer cell activity in PBL. In our study, the cloning efficiencies, Ag-specific CTL activity and non-MHC-restricted cytotoxicity of CTL clones generated in IL-2 were compared to those generated in IL-4. In a first experiment, T cells were stimulated with the EBV-transformed B cell line JY and cloned 7 days later with feeder cells and either IL-2 or IL-4. In a second experiment, stimulation of the T cells was carried out in the presence of IL-2 plus anti-IL-4 antibodies or IL-4 plus anti-IL-2 antibodies in order to block the effects of IL-4 and IL-2, respectively, produced by the feeder cells. Although the cloning efficiencies in the second experiment were lower than those obtained in the first experiment, the cloning efficiencies obtained with IL-2 or IL-4 were similar in both experiments. The overall proportion of TCR alpha beta+ T cell clones cytotoxic for the stimulator cell JY established in IL-2 or IL-4 were comparable. A striking difference between the clones obtained in IL-2 or IL-4 was that a large proportion of the clones obtained in IL-4 expressed CD4 and CD8 simultaneously, whereas none of the clones isolated in IL-2 were double positive. Also gamma delta+ T cell clones could be established with IL-4 as a growth factor. TCR gamma delta+ T cell clones isolated in either IL-2 or IL-4 were CD4-CD8- or CD4-CD8+, but the proportion of CD4-CD8+ clones isolated in IL-4 was higher. Interestingly, one TCR gamma delta+ clone isolated in IL-2 was CD4+CD8-. Most of the TCR alpha beta+ and TCR gamma delta+ CTL-clones isolated in IL-2 lysed the NK cell sensitive target cell K562. In contrast, only a small proportion of the TCR alpha beta+ or TCR gamma delta+ CTL clones isolated in IL-4, lysed K562. One TCR gamma delta+ T cell clone (CD-124) isolated in IL-4 and subsequently incubated in IL-2 acquired lytic activity against K562.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Line↗
PubMed1987

A novel tetracycline from Actinomadura brunnea. Fermentation, isolation and structure elucidation.

A novel tetracycline antibiotic, Sch 33256, was isolated from a culture broth of a new species of Actinomadura. The antibiotic was isolated by solvent extraction, Sephadex G-25 column chromatography and crystallization. The structure was determined by comparison of the spectra with that of chlortetracycline. Spectroscopic analysis of the compound yielded 2'-N-methyl-8-methoxychlortetracycline as the proposed structure.

Bacteria↗
PubMed1984

A novel phenazine antifungal antibiotic, 1,6-dihydroxy-2-chlorophenazine. Fermentation, isolation, structure and biological properties.

A novel, solvent extractable, antibiotic complex has been purified from the fermentation broth of an unusual member of the genus Streptosporangium. Two of the major components were isolated from the complex by alumina column chromatography. One of the components was identified as a previously reported compound, 1,6-dihydroxyphenazine. The other component was a novel chlorine containing phenazine, 1,6-dihydroxy-2-chlorophenazine, which exhibited broad spectrum antifungal activity in vitro against dermatophytes and Candida.

Actinomycetales↗
PubMed1983

The hazimicins, a new class of antibiotics. Taxonomy, fermentation, isolation, characterization and biological properties.

The hazimicins, a new class of broad spectrum antibiotics with at least 2 active components (5 and 6), were isolated from the fermentation of Micromonospora echinospora var challisensis SCC 1411. The complex was separated from the broth by a solvent extraction procedure, and the individual components were separated by column chromatography. The two primary active components are isomers, with unique structures shown to be di-tyrosine analogs containing two isonitrile groups. The antibiotic has in vitro activity against Gram-positive and Gram-negative bacteria, and in vitro activity against yeasts and dermatophytes.

Anti-Bacterial Agents↗
PubMed1981

Kijanimicin (Sch 25663), a novel antibiotic produced by Actinomadura kijaniata SCC 1256. Fermentation, isolation, characterization and biological properties.

A novel antibiotic complex has been isolated form the fermentation broth of a new species of Actinomadura, A. kijaniata SCC 1256. The complex was separated form the broth by a solvent extraction procedure and consists of 1 major component, designated kijanimicin, and 3 minor components. Kijanimicin was isolated form the complex by column chromatography and/or preparative high pressure liquid chromatography. Structurally the compound is a unique, large acid enol antibiotic and possesses an unusual in vitro spectrum of activity against some Gram-positive and anaerobic microorganisms. In vivo it has also shown interesting activity against malaria.

Aminoglycosides↗
PubMed1980

Evaluation of netilmicin susceptibility discs using bacteria with known aminoglycoside resistance patterns: correlation of in vitro and in vivo test results.

Data obtained with 30 micrograms netilmicin discs on Mueller-Hinton agar have been compared to MIC values obtained in Mueller-Hinton broth. Regression analysis was used to determine susceptibility cutoff points for Pseudomonas and non-Pseudomonas gram-negatives. The utility of these cutoff points for the determination of netilmicin sensitivity was evaluated in tests with 1405 clinical isolates. These tests employed 897 sensitive isolates and 508 strains with known aminoglycoside resistance patterns. Netilmicin was shown to be active against sensitive isolates and those strains with resistance patterns corresponding to the presence of: ANT(2"), ANT(2")+AAC(6'), ANT(4'), APH(2")+AAC(6'), APH(3')-IV and AAC(3)-I modifying enzymes. PD50 values obtained in experimental mouse infection studies with gentamicin, tobramycin and amikacin as well as netilmicin confirmed the excellent activity of netilmicin against strains with the above-mentioned resistance patterns. The good correlation between disc sensitivity test results and MIC and PD50 values suggest that a 30 micrograms netilmicin disc can be used to predict the netilmicin susceptibility of clinical isolates.

Aminoglycosides↗
PubMed1979

Biosynthetic pathway leading to gentamicin C2b.

Incubation of Micromonospora purpurea SC 1210 (NRRL 5467) with L-[methyl-14C]methionine yielded [methyl-14C]gentamicin A and methyl-14C-labeled antibiotic JI-20A in a molar radioactivity ratio of 9:2. We did not isolate methyl-14C-labeled gentamicin X2, which was expected as an intermediate based on the biosynthetic pathways proposed by others. Addition of methyl-14C-labeled antibiotic JI-20A to M. purpurea SC 1124 (NRRL 8102) yielded [methyl-14C]-gentamicin C1a and [methyl-14C]gentamicin C2b in variable molar radioactivity ratios. These data do not support the biosynthetic pathway leading to gentamicin C2b proposed by Testa and Tilley.

Fermentation↗