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Biomedical subjects

J Watson

Publications and source records attributed to J Watson.

At least 19 recordsLinked to original sources
PubMed1979

Continuous proliferation of murine antigen-specific helper T lymphocytes in culture.

Murine helper T cells activated to sheep or horse erythrocyte antigens in vivo have been established as continuous cell lines in culture. T cells require the presence of a T-cell growth factor (TCGF) for continuous proliferation. TCGF purified from murine, rat, or human sources all stimulate murine T-cell growth. The T-cell mitogens concanavalin A and phytohemagglutinin do not stimulate cell proliferation in continuous T-cell lines. All cells that grow in the presence of TCGF express Thy-1 antigens. Helper activity of T-cell lines is both antigen specific and effective for syngeneic or F1 B cells. Supernates from T-cell lines do not contain antigen-specific or nonspecific helper factors. Although several T-cell lines have shown stable helper activity for greater than 50 wk in culture, other cell lines have shown a gradual decline in effector function. The procedure used to establish and maintain proliferation of T cells in culture should be suitable for the selection and growth of antigen-specific effector T cells from each subclass.

Animals↗
PubMed1979

Biochemical and biological characterization of lymphocyte regulatory molecules. I. Purification of a class of murine lymphokines.

Murine spleen cells activated by concanavalin A (Con A) in culture produce a class of lymphokine molecules which possess biological activity in a number of lymphocyte response assays. Lymphokines with a mol wt of 30,000, as estimated from gel filtration studies, can be resolved into two components which differ by charge, with isoelectric point (pI) values of 4.3 and 4.9, respectively. Both components stimulate (a) the growth of established T-cell lines in culture, (b) the proliferation of thymocytes in the presence of Con A under culture conditions where Con A alone is nonmitogenic, (c) the induction of antibody responses to heterologous erythrocyte antigens in athymic (nude) spleen cultures, (d) the generation of cytotoxic T lymphocytes (CTL) in thymocyte cultures, and (e) the generation of CTL in nude spleen cultures. In each of these culture systems we suggest that the assays are detecting a single class of lymphokine which acts directly on activated T cells. Nonactivated T cells must be stimulated by either antigen or mitogen before becoming responsive to lymphokine, but do not require antigen or mitogen for continued growth with lymphokine. The two molecular species, separable by isoelectric focusing are referred to as the T-cell growth factor (TCGF). A lymphokine, similar in size (30,000 daltons) to TCGF but heterogeneous in charge (pI 3.0--4.0), stimulates immune responses to erythrocyte antigens in T-cell-depleted spleen cultures but has no stimulatory activity in the other lymphocyte assay systems described. The data have been interpreted as showing the two molecular forms of murine TCGF (pI 4.3 and 4.9) are responsible for many of the lymphokine activities described elsewhere as thymocyte mitogenic factor, nonspecific T-cell-replacing factor and killer helper factor or costimulator. The other lymphokine, separable from TCGF by charge, appears to have true T-cell-replacing activity.

Animals↗
PubMed1979

Genetic control of the immune response to collagen. II. Antibody responses produced in fetal liver restored radiation chimeras and thymus reconstituted F1 hybrid nude mice.

The level of antibody produced in response to calf skin collagen in mice is influenced by genes which are closely linked to the I region of the H-2 major histocompatibility complex. This influence is shown to be expressed during lymphoid maturation by testing the antibody responsiveness to collagen in two types of chimeric mice. First, high responder and low responder parental strain mice were lethally irradiated and restored with fetal liver cells from (high X low responder) F1 mice. These F1 leads to parent chimeras exhibited an immune response phenotype characteristic of the irradiated parental strain animals, establishing that H-2 determinants of the host affect antigen responsiveness. Second, (high X low responder) F1 congenitally athymic (nude) mice were restored with fetal thymus transplants from either high or low responder parental strain mice. After a period of maturation these mice were shown to be competent for a T-dependent IgG response to SRBC. The responsiveness to collagen in these mice was characteristic of the parental strain thymus donors, indicating that the expression of H-2 determinants in thymic tissue during lymphoid maturation influences the antibody response phenotype expressed by mice.

Animals↗
PubMed1979

Effect of oestradiol-17 beta and gonadotrophins on prostaglandin production by pre-ovulatory pig follicles superfused in vitro.

Pre-ovulatory pig follicles were superfused in vitro with oestradiol, LH or FSH in the presence and absence of indomethacin. Prostaglandin E2 ANd F2 alpha and oestradiol were measured in the same samples of superfusate. LH and FSH caused an increase in levels of both prostaglandins (approximately 2-fold) but the most marked effect was of oestradiol in PGE2 where a 4-fold increase in levels above controls was observed. In all cases indomethacin inhibited the effects. Both gonadotrophins caused an increase in oestradiol production although the response to LH was much slower than to FSH. The results show a possible relationship between FSH, oestradiol and PG synthesis in the pre-ovulatory pig follicle.

Animals↗
PubMed1979

Prostaglandin E-2-9-ketoreductase in ovarian tissues.

The existence of the enzyme prostaglandin E-2-9-ketoreductase which can convert prostaglandin E-2 to prostaglandin F-2 alpha was indicated in experiments with pig and human ovarian tissues in vitro, using radioimmunoassay methods and a superfusion technique. Further studies involving radiotracer techniques demonstrated that the enzyme was localized in the high-speed (105 000 g) supernatant fraction of human, pig and rat luteal tissue and human stromal tissue. The enzyme was shown to be NADPH-dependent and its activity in luteal tissue increased in the order : pig less than human less than rat.

Animals↗
PubMed1979

Steroid and prostaglandin secretion by the corpus luteum, endometrium and embryos of cyclic and pregnant pigs.

Prostaglandin F2 alpha (PGF2 alpha) secreted by the reproductive tissues of the pig in vitro was measured and it was found that the levels secreted by the corpus luteum and endometrium of early pregnant sows were significantly lower than those secreted by tissues during the late stage of the oestrous cycle. They were, however, comparable to levels secreted by tissues from the mid-stage of the oestrous cycle. Embryos also secreted significant amounts of PGF2 alpha. Secretion of progesterone and oestradiol by the corpora lutea of both cyclic and pregnant pigs fell within accepted limits but embryos were also found to secrete significant amounts of oestradiol. The results suggest that luteal maintenance in the early pregnant pig is unlikely to be directly due to reduced synthesis of PGF2 alpha.

Animals↗
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↗