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Biomedical subjects

J Watson

Publications and source records attributed to J Watson.

At least 37 records · Page 2Linked to original sources
PubMed1979

The purification and quantitation of helper T cell-replacing factors secreted by murine spleen cells activated by concanavalin A.

A microculture assay with low numbers of athymic (nude) spleen cells has been used to quantitate the helper T cell-replacing activity secreted by concanavalin A-treated spleen cells. This quantitation allows an estimate of the recovery of biologic activity during concentration from culture supernatants by salt precipitation, and purification by gel filtration, ion exchange chromatography, and isoelectric focusing. The T cell-replacing activity is found in protein of 30 to 40,000 daltons size as estimated by gel filtration, but shows heterogeneity in electric charge. The activity is active at concentrations of less than 10(-9) M, and is strictly antigen dependent in its mode of action.

Ammonium Sulfate↗
PubMed1979

Helper T cell-replacing factors secreted by thymus-derived cells and macrophages: cellular requirements for B cell activation and synergistic properties.

The biologic activities of helper T cell-replacing factors derived from concanavalin A-stimulated murine T cells (TRF-T) and from lipopolysaccharide-activated macrophages (TFR-M) have been compared. TRF-T stimulates immune responses to heterologous erythrocyte antigens (SRBC and BRBC) in T cell-depleted spleen cultures but not in macrophage-depleted spleen cultures. TRF-M stimulates immune responses in both T cell-depleted and macrophage-depleted spleen cultures. Under conditions where LPS stimulates the release of TRF-M from cultures of activated macrophages, TRF-t has no effect on TFR-M production. Thus. TRF-T does not appear to function by stimulating the release of TRF-M from macrophages. In macrophage-depleted spleen cultures, saturating concentrations of TRF-T and TRF-M when mixed together exhibit striking synergistic effects on the induction of immune responses to erythrocyte antigens. The kinetics of the synergistic effects of TRF-M and TRF-T are consistent with an effect of TRF-M on the production of TRF-T sensitive B cells.

Animals↗
PubMed1979

Genetic and biochemical evidence for the involvement of a bacterial component in the mitogenic properties of polyribonucleotides on murine B lymphocytes.

The mitogenic response of C3H/HeJ mice to the B cell mitogens, poly C and poly I, is approximately one-half the response measured in various LPS-responder strains. C3H/HeJ mice respond normally to poly I:C, the heteroduplex polymer. The low responder phenotype of C3H/HeJ mice to poly C and poly I is shown by an analysis of (C3H/HeJ x C57BL/6J-By-Ps)F1 X C3H/HeJ backcross progeny to result from a gene locus that is closely linked or identical to the defective LPS response locus expressed by the C3H/HeJ strain. The entire mitogenic activity in poly C preparations and most of the mitogenic activity in poly I preparations is insensitive to ribonuclease degradation. Hot aqueous phenol extraction of the polynucleotides separates the majority of the mitogenic activity that is soluble in the combined interface and phenol phase fraction from the aqueous soluble polynucleotides. The ribonuclease-insensitive, phenolsoluble contaminant elicits a reduced response in C3H/HeJ mice as compared to an LPS responder strain. We conclude that 1) poly C has no inherent mitogenic activity; 2) poly I preparations contain both ribonucleasesensitive and insensitive mitogenic activities; 3) the ribonuclease-resistant mitogenic activity in polynucleotide preparations has properties unlike those of LPS or lipid A; and 4) the product of LPS response gene has an effect upon the mitogenic stimulation of spleen cells by the contaminant.

Animals↗
PubMed1978

The Warble Fly Orders.

The provisions and the operational aspects of the new Warble Fly Orders are described. The new Orders will apply between March 15 and July 31 and during this period owners of cattle showing visible or palpable signs of warbles must treat them with a systemic warble fly dressing. During this period no infested cattle may be moved, even to a slaughterhouse, unless they have been treated and are accompanied by a statutory declaration of treatment.

Animals↗
PubMed1978

Genetic control of endotoxic responses in mice.

A number of altered immunologic responses to lipopolysaccharide (LPS) in C3H/HeJ mice result from the expression in B lymphocytes of a defective genetic locus, termed Lps. Lps has been mapped to chromosome 4 between two loci, Mup-1 and Ps. As it is difficult to type individual mice for LPS responsiveness in more than one type of assay, we have utilized Mup-1 as a genetic marker to correlate LPS responses in mice to the expression of the Lps locus. Three nonlymphoid responses to LPS have been examined in 12 recombinant inbred strains of mice and in a backcross linkage analysis, and are all regulated by the expression of the Lps locus. These responses are hypothermal changes in body temperature, and the elevation in serum levels of a colony stimulating factor and the precursor of the secondary amyloid protein AA. Therefore, the initiation of LPS responses in different cell types in mice involve the expression of a common locus. These linkage studies provide a means for analyzing the genetic control of many of the diverse reactions of the endotoxic response to LPS.

Alleles↗
PubMed1978

Progesterone secretion by the corpus luteum of the early pregnant pig during superfusion in vitro with PGF-2alpha, LH and oestradiol.

Corpora lutea obtained from pregnant sows (Days 18-22) were superfused in vitro for 2-4 h with PGF-2alpha and for 3 h with LH or oestradiol or combinations of PGF-2alpha with LH or oestradiol. LH but not oestradiol stimulated progesterone secretion while superfusion for a minimum of 3 h with PGF-2alpha caused an irreversible decrease in progesterone secretion. LH and PGF-2alpha were mutually antagonistic while oestradiol did not inhibit the luteolytic action of PGF-2alpha.

Animals↗
PubMed1978

The genetic mapping of a defective LPS response gene in C3H/HeJ mice.

The expression of a defective LPS response gene Lps and the major urinary protein (Mup-1) are concordantly inherited in backcross (C3H/HeJ x C57BL/6J)F1 x C3H/HeJ mice, indicating genetic linkage of these loci. Mup-1 is known to be linked to the brown coat color locus on chromosome 4 in mice; thus Lps can now be assigned to chromosome 4. A value of 0.06 +/- 0.02 has been estimated for the recombination frequency between Mup-1 and Lps. We have used the polysyndactyly (Ps) mutation further to localize Lps on chromosome 4. Lps is located between the Mup-1 and Ps loci.

Animals↗
PubMed1978

Effect of a synthetic adjuvant on the induction of primary immune responses in T cell-depleted spleen cultures.

N-acetylmuramyl-L-alanyl-D-isoglutamine (muramyl dipeptide) stimulates in vitro primary immune responses to SRBC in T cell-depleted (nude) spleen cultures. The stimulation of immune responses by muramyl peptide was antigen dependent. A microculture system was used to compare the T cell-replacing activities of several structural analogues of muramyl dipeptide and to compare the activity of muramyl dipeptide to helper T cells. In a limiting dilution analysis with excess helper T cells or muramyl dipeptide, the frequency of B cell precursors that respond to SRBC was similar, ranging from 1.5 to 5 X 10(-5). Decreasing the cell density in microcultures did not affect the efficiency of B cell precursor responses in the presence of muramyl dipeptide. Muramyl dipeptide was examined for mitogenic activity in spleen cell cultures. In serum-free medium, muramyl dipeptide stimulates slight (3-fold) increases in DNA synthetic activity. In medium supplemented with 5 to 20% fetal calf serum, muramyl dipeptide showed no significant mitogenic activity. There are a number of possible explanations for the T cell-replacing activity of muramyl dipeptide. The most likely is that muramyl dipeptide interacts directly with B cells to mimic the helper T cell signal in the inductive stimulus.

Adjuvants, Immunologic↗