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Biomedical subjects

A Lichtman

Publications and source records attributed to A Lichtman.

6 recordsLinked to original sources
PubMed1996

Mouse Eotaxin expression parallels eosinophil accumulation during lung allergic inflammation but it is not restricted to a Th2-type response.

A model of lung eosinophilia based on the repeated exposure of mice to aerosolized OVA has been used to identify C-C chemokine genes expressed at stages of massive eosinophil infiltration. We describe the identification and cloning of a cDNA that encodes a mouse C-C chemokine with 68% amino acid identity to guinea pig Eotaxin. The recombinant protein encoded by this gene displays potent and specific chemotactic activity for eosinophils, both in vivo and in vitro. Its mRNA levels parallel the kinetics of eosinophil accumulation in the lung during the experimentally induced eosinophilia and it is mainly produced by type I alveolar epithelial cells. The mRNA expression of mouse Eotaxin is not restricted to Th2 T cells in vitro and is independent of the development of a Th2-type response during N. brasiliensis infection, in vivo.

Amino Acid Sequence↗
PubMed1994

Differentiation of the T helper phenotypes by analysis of the methylation state of the IFN-gamma gene.

Th1 and Th2 CD4+ T cell clones have been defined by their ability to produce different lymphokines. However, the processes by which CD4+ T cells differentially regulate lymphokine gene expression have not been well defined. In this report, we demonstrate that the methylation status of a CpG dinucleotide contained within a TATA proximal regulatory element of the IFN-gamma promoter correlates with the transcription of the gene. In murine Th1 clones and two human CD4+ Th0 clones, this site is either completely or partially hypomethylated, whereas in murine Th2 clones this site is > 98% methylated. Treatment of murine Th2 clones with 5-azacytidine, an agent that inhibits methylation of the DNA, converts these cells to IFN-gamma producers. Additional targets for methylation outside the transcriptional control regions of the IFN-gamma genetic locus were found to be hypomethylated in Th2 cells but not in Th1 cells. Electrophoretic mobility shift assays (EMSA) revealed at least five distinct protein-DNA complexes that are formed with an oligonucleotide containing the IFN-gamma promoter TATA proximal regulatory element, and in vitro methylation of this site results in a loss of these three complexes. Furthermore, a comparison of nuclear extracts prepared from Th1 and Th2 clones revealed that the EMSA patterns were qualitatively similar but differed quantitatively. In addition, transient transfection of a murine IFN-gamma promoter-chloramphenicol acetyl transferase (CAT) gene construct into both Th1 and Th2 clones produced CAT activity that was not inducible by anti-CD3, indicating that hypomethylation per se of the promoter alone is not sufficient for inducible gene expression.

Animals↗
PubMed1975

The early effects of ouabain on potassium metabolism and rate of proliferation of mouse lymphoblasts.

Murine lymphoblasts grown in suspension culture in the presence of ouabain showed a dose dependent and sequential decrease in 86Rb+ (K+ analogue) influx, cellular potassium content, and growth rate. An increase in eosin staining and a decrease in cell number was observed after two hours in the presence of 1 mM ouabain; 1 muM ouabain was without effect on any of the parameters measured. Ouabain inhibition was rapidly and completely reversible at concentrations that were not cytotoxic.

Animals↗