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Biomedical subjects

J C Jenson

Publications and source records attributed to J C Jenson.

12 recordsLinked to original sources
PubMed2003

In vitro immunomodulatory activity of ruthenium complexes.

OBJECTIVE AND DESIGN: We have explored the in vitro immunomodulatory effects of pure ruthenium red and a series of pyridine and imidazole substituted ruthenium complexes (RCs). MATERIAL: Human peripheral blood lymphocytes and purified T cells were used in these studies along with various cell lines. METHODS: Cells were treated with dilutions of RCs and assessed in various assays of immune function, cytotoxicity and cell cycle progression. RESULTS: RCs efficiently blocked T cell receptor (TCR)-mediated stimulation (IC(50)'s in the low nM range) of human peripheral blood lymphocytes (hPBL) by various agents, including tetanus toxoid, alloantigens, superantigens, and receptor-specific antibodies. RCs are not cytotoxic to T cells. Antiproliferative activity was also observed for B cells. Some non-lymphoid cell lines or primary cultures showed sensitivity to the RCs, but only at higher concentrations. The inhibitory effect on human T cells was assessed and demonstrated at the level of proliferation (DNA synthesis), IL-2 secretion, and IL-2 receptor (CD25) upregulation. RCs also inhibited IL-2-mediated proliferation of antigen-induced T-cell blasts and the IL-2-dependent T cell line Kit-225. Cell cycle analysis indicates that RCs inhibit the progression of activated T cells from G(0)/G(1) to S phase. CONCLUSIONS: Since the mechanism of T cell inhibition by RCs appears to be different than that of rapamycin (RAP) or cyclosporin A (CsA), they may provide a new tool to investigate intracellular signaling in T cells, and may present novel opportunities for immunosuppression

Animals↗
PubMed1996

Naphthalene sulfonate polymers with CD4-blocking and anti-human immunodeficiency virus type 1 activities.

PIC 024-4 and PRO 2000 are naphthalene sulfonate polymers that bind to CD4 with nanomolar affinity and block binding of gp120. Both have activity against human immunodeficiency virus type 1 in H9 cells, peripheral blood mononuclear cells, and primary monocyte/macrophages, are synergistic with zidovudine, and do not inhibit tetanus toxoid-stimulated T-cell proliferation at anti-human immunodeficiency virus type 1 concentrations.

Animals↗
PubMed1990

Purification and characterization of the bombesin/gastrin-releasing peptide receptor from Swiss 3T3 cells.

The bombesin/gastrin-releasing peptide (GRP) receptor was solubilized from Swiss mouse 3T3 cell membranes in an active form and was purified about 90,000-fold to near homogeneity by a combination of wheat germ agglutinin-agarose and ligand affinity chromatography. The purified receptor displayed a single diffuse band with a Mr of 75,000-100,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After treatment of the receptor with N-glycanase, removing N-linked oligosaccharide moieties, the protein yielded a Mr = 38,000 band. These results agree with the Mr value estimated for the GRP receptor that was labeled on Swiss 3T3 cells by cross-linking to 125I-GRP1-27. GRP1-27 bound to the purified receptor with a Kd of 0.038 +/- 0.019 nM. By comparison, the soluble receptor in unfractionated extracts and intact membranes displayed a Kd for GRP1-27 of 0.036 +/- 0.003 nM and 0.13 +/- 0.04 nM, respectively. The relative potencies of a series of GRP analogs for the soluble receptor and intact membranes indicated that the extraction procedure did not significantly alter the receptor's ligand binding specificity. However coupling of the receptor to its guanyl nucleotide regulatory protein was not maintained in the soluble extract, and a G-protein did not co-purify with the receptor. Physiological concentrations of NaCl greatly inhibited the binding of some GRP analogs to the receptor, while the binding of other analogs was not affected. A domain on the GRP molecule involving Lys-13 or Arg-17 was identified which promoted binding to the GRP receptor under conditions of low ionic strength. These findings aided the development of an effective ligand affinity resin for the purification of the GRP receptor.

Animals↗
PubMed1988

Characterization of a factor(s) which synergizes with recombinant interleukin 2 in promoting allogeneic human cytolytic T-lymphocyte responses in vitro.

Supernatants from PHA-activated human peripheral blood mononuclear cells, depleted of virtually all IL-2 activity by an anti-rIL-2 immunoadsorbent column, contain a factor(s) which synergizes with rIL-2 in facilitating the generation of allogeneic human CTL responses in vitro. This factor, provisionally termed CTL maturation factor (TcMF), did not appear to promote CTL responses in the absence of rIL-2. Furthermore, it acted later than IL-2 in facilitating CTL responses and could not be replaced by recombinant IFN-gamma. In this report we show that rIFN-alpha, rIL-1 alpha, and rIL-1 beta likewise lack TcMF activity. The TcMF activity in lymphokine-containing culture supernatants could be eliminated by trypsin or pronase but not by neuraminidase or RNase. Gel filtration revealed two peaks of TcMF activity, one at 12,000 to 25,000 Da and the other at 45,000 to 65,000 Da. Isoelectrofocusing demonstrated substantial charge heterogeneity. The majority of TcMF activity was recovered between pI 4.0 and pI 5.5 with a minor component at pI 6.5, corresponding to the areas in which IL-1 activity was also found. However, TcMF activity could be separated from IL-1 by reverse-phase HPLC. Moreover, TcMF recovered following reverse-phase HPLC was also found to be depleted of IL-4 activity. These studies suggest that TcMF activity is mediated by a protein(s) distinct from IL-1, IL-2, IL-4, and interferon-alpha or-gamma.

Biological Products↗
PubMed1987

Biochemical and functional analysis of soluble human interleukin-2 receptor produced in rodent cells. Solid-phase reconstitution of a receptor-ligand binding reaction.

The binding of interleukin-2 (IL-2) to the IL-2 receptor (IL-2R) on human T-cells is a key regulatory event which is absolutely required for T-cell-mediated immune responses. To understand further this binding event, we modified the human IL-2R gene to encode a secreted form of IL-2R. Secreted IL-2R was then expressed at very high levels (approximately 11 micrograms/10(6) cells/48 h) in rodent cells using gene-linked co-amplification. The soluble forms of IL-2R were shown to retain IL-2 affinity shown by cell-surface IL-2R (Kd approximately 18 nM) and were purified to homogeneity using IL-2 affinity chromatography. Purified, recombinant IL-2R and biotinylated IL-2 were used to establish a solid-phase receptor binding assay. Binding of IL-2-biotin was demonstrated to be dose-dependent at concentrations ranging from 10 to 1000 ng/ml, and the specificity of receptor-ligand binding was demonstrated by competition with non-biotinylated IL-2 and with anti-receptor antibodies known to block IL-2 binding in vivo. This immunosorbent receptor assay offers a simple and rapid method for studying the binding of IL-2 to human IL-2R.

Animals↗
PubMed1982

Binding of benzo[a]pyrene to histones and altered affinity of modified histone 1 for deoxyribonucleic acid.

The covalent binding of benzo[a]pyrene (B[a]P) to acid extractable chromosomal proteins and the subsequent effect on histone 1-DNA interaction have been characterized in a model system by utilizing calf thymus nuclei as targets and rat liver microsomes as an exogenous source of enzymes for the metabolic activation of B[a]P. A two-step ion-exchange chromatography and desalting procedure was employed for removing noncovalently bound B[a]P and other contaminants. Fluorography of acetic acid-urea and Triton-acetic acid-urea-polyacrylamide gels indicated that H1 and H3 were the only principal histone targets in [3H]B[a]P-modified calf thymus nuclei. The validity of this assignment was confirmed by comparison of the chromatographic distributions of [3H]B[a]P cpm among peptides derived from the HClO4- soluble (H1) and HClO4-insoluble (core histones) protein fractions to the distributions obtained for authentic individual histone fractions. Comparison of amino acid compositions in individual peptide fractions which bound [3H]B[a]P differentially yielded some insight into the probable target amino acid residues for B[a]P binding. On the basis of electrophoresis in polyacrylamide gels, it appeared as if B[a]P had bound to multiple subfractions of H1 and H3. The equivalent distribution of covalently attached [3H]B[a]P among the major peptides of H1 and H3 modified either in intact nuclei or while free in solution implied that the relative accessibility of major portions of the H1 and H3 molecules for covalent B[a]P binding is not affected by interactions with DNA or other chromosomal proteins. Covalent attachment of [3H]B[a]P to purified H1 reduced the affinity of this histone for DNA-cellulose.

Animals↗
PubMed1982

Lysines of histone 1 represent the principal target for covalent binding of microsomally activated benzo[a]pyrene in vitro.

The principal target amino acid residue for covalent binding of metabolically activated [3H]benzo[a]pyrene (B[a]P) to histone 1 (H1) has been identified. Highly purified calf thymus H1 was modified by incubation with [3H]B[a]P in the presence of rat liver microsomes. The relative distribution of [3H]B[a]P versus specific amino acids among the N-bromo-succinimide peptides of H1 suggested that lysine may be the target. This was tested by selectively blocking the nucleophilic amino groups of lysine by amidination prior to [3H]B[a]P binding. Increasing levels of amidination of H1 resulted in corresponding decreases in the reactivity of this histone toward [3H]B[a]P. Amidination of 93% of the lysines blocked 87% of the [3H]B[a]P binding indicating that lysine was the principal target. N-terminal amino acid sequencing of [3H]B[a]P-modified H1 confirmed that lysine residues had bound [3H]B[a]P.

Benzopyrenes↗
PubMed1980

Structurally unique basic protein coextracted with histones from calf thymus chromatin.

A histone-like protein that is rich in alanine and lysine (protein AK) has been obtained in homogeneous form by high-resolution gel filtration of H2SO4 extracts of calf thymus chromatin. Protein AK: (i) migrates as a single band in polyacrylamide gel electrophoresis in both acetic acid/urea and sodium dodecyl sulfate; (ii) is a basic protein; (iii) lacks tryptophan; (iv) is not extracted from chromatin with 0.35 M NaCl; and (v) is not soluble in 0.75 M HClO4. Protein AK is distinguished from the high-mobility group (HMG) proteins on the basis of these latter solubility characteristics and from the histones and protein A24 on the basis of amino acid composition and distribution of tryptic peptides in two-dimensional chromato-electrophoresis. In addition, protein AK is distinguished from the HMG proteins, the histones, and protein A24 on the basis of its mobility in two polyacrylamide gel electrophoresis systems. The amino acid composition of protein AK resembles that of HU, a basic DNA-binding protein found in Escherichia coli.

Amino Acids↗
PubMed1974

Concancvalin A binding proteins of lymphoid cell surface.

A Concanavalin A binding protein of chicken lymphoid cells was isolated by affinity chromatography of intact lymphoid cells. This protein with a mol wt of 160,000 daltons revealed two peptides (30,000 and 20,000 daltons) in SDS-acrylamide gel electrophoresis.

Animals↗