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Y Namba

Publications and source records attributed to Y Namba.

At least 181 records · Page 10Linked to original sources
PubMed1977

Regulatory substances produced by lymphocytes. V. Production of inhibitor of DNA synthesis (IDS) by proliferating T lymphocytes.

The conditions neccessary for production of inhibitor of DNA synthesis (IDS) by rat lymphocytes were investigated. In concanavalin A (Con A)-stimulated lymph node cell (LNC) cultures, IDS production was not detected in the culture supernatant during the first 24 hr, and it increased gradually after that to reach a maximum at 3 to 4 days. When the cells were pretreated with mitomycin C, IDS was not produced, suggesting that DNA synthesis of LNC or a LNC subpopulation is necessary for IDS production. In contrast, Con A-stimulated spleen cells priduced a high level of IDS within 24 hr, and its production fell off sharply thereafter. Con A-stimulated rat thymocytes also produced IDS reaching a maximum at 2 to 3 dyas. However, thymus cells from rats treated with hydrocortisone 48 hr previously did not produce IDS. This finding implies that cortisol-sensitive (cortical) thymocytes are capable of producing IDS and cortisol-resistant (medullary) thymocytes are not. IDS production by lymphoblasts was proportional to cell number and unaffected eith by cell density (1 to 10 x 106/ml) or by the concomitant presence of normal cells from spleen, lymph node, or thymus. Thus Con A-stimulated cells, after becoming blasts, appear to produce IDS automatically wihtout affecting or being affected by other cells. Both spleen and thymus cells from rats injected with a large dose of antigen (ovalbumin, 100 mg, i.p.) 24 hr in advance produced substantial amounts of IDS in culture within 24 hr in the absence of mitogen or additional antigen, but not the cells from rats injected with an immunizing dose (1 mg) of the same antigen. The cells producing IDS in the spleen were shown to be adherent to glass wool, and those in the thymus were partially so. IDS production by antigen-stimulated spleen cells was abrogated by injecting rats with bromodexyuridine (BUdR) at 0 and 12 hr after the ovalbumin. These findings suggest that a subpopulation ofadherent spleen cells (possibly resembling cortical thymocytes), which begins to proliferate within a few hours after a large dose of systemic antigen, produces IDS. This may account for increased nonspecific suppressor activity observed at the same time.

Animals↗
PubMed1976

Phosphatidylcholine content and fatty acid composition of tracheal and gastric liquids from premature and full-term newborn infants.

The phosphatidylcholine content and fatty acid composition of tracheal and gastric liquids from newborn full-term and premature (30-36 weeks) infants were studied. Phosphatidylcholine accounted for about 70% of the total phospholipids in both liquids from the full-term infants but only 55-57% of those from the prematures. There was a significant correlation between tracheal and gastric liquids in the fatty acid composition of phosphatidylcholine. There were significant differences in fatty acid composition between the full-term and premature liquids. These differenences were most apparent in the gastric liquid. It is suggested that phospholipid or fatty acid analysis of tracheal or gastric liquids from newborn infants can be used in the assessment of pulmonary maturity.

Fatty Acids↗
PubMed1976

Analysis of T-cell-specific functions in continuous lymphocytic cell lines. II. A T-cell line which forms rosettes with normal thymocytes of the same species.

Four T-cell lines of mouse origin (EL-4, S-49, R-1, and L-5178Y) with similar characteristics (Thy-1-positive, and PHA-sensitive) were tested for reactivity with various antigens. EL-4 cells alone were shown to form rosettes at 4 degrees C with thymocytes (positive for either Thy-1.1 or Thy-1.2) and with Thy-1-positive lymph node cells of various mouse strains. Comparable rosette formation did not occur with Thy-1-negative lymphnode cells or red blood cells, nor with rat or rabbit thymocytes. The thymocytes which attached to the tumor cells formed a cluster at one pole of the cell after warming at 37 degrees C for 10 min. After incubation for 40 min at 37 degrees C, most of the rosettes disappeared. This process was blocked by sodium azide and dinitrophenol, suggesting that the movement of thymocytes to one pole of the tumor cell and subsequent release are energy-dependent. These results suggest that the EL-4 cell line, originally derived from a carcinogen-induced lymphoma of C57BL/6, may have been an autoimmune lymphoma reactive against T cells.

Animals↗
PubMed1976

Regulatory substances produced by lymphocytes. III. Evidence that lymphotoxin and proliferation inhibitory factor are identical and different from the inhibitor of DNA synthesis.

L cell mutant lines which were considerably more resistant to rat lymphotoxin (LT) than the original cell line were obtained by periodic additions of LT, partially purified from sensitized lymph node cell culture supernatants by DEAE-cellulose chromatography and Sephadex gel filtration. Addition of actinomycin D to cultures of these mutant cells abrogated resistance to LT, suqgesting that resistance was not due to a loss of LT receptors but probably to increased activity of a repair mechanisms. These mutant lines were also more resistant to the proliferation inhibitory effect of LT in low concentration and to that of diluted culture supernatants of lymph node cells stimulated with antigen (ovalbumin) than the original cell line, but they remained as sensitive to inhibitor of DNA synthesis (IDS) as the original line. The mutant lines also remained fully sensitive to both complement-dependent lysis by antibody and antibody-dependent cellular cytotoxicity, but showed increased resistance to the killing effect of rat lymph node cells sensitized with orginal L cells in vivo. These findings suggest that the lymphotoxic substance partially purified and characterized in this and in the previous paper may be an important mediator of T cell-mediated cytotoxicity.

Animals↗
PubMed1975

Regulatory substances produced by lymphocytes. II. Lymphotoxin in the rat.

Rat lymphotoxin (LT), a soluble mediator which kills L cells (mouse fibroblasts) within 48 hr, was partially purified by conventional protein fractionation procedures from the culture supernatants of rat lymph node cells stimulated with ovalbumin in vivo and rechallenged with the same antigen in vitro. It appeared, from the elution pattern of DEAE-cellulose chromatography, to be a neutral or slightly basic protein and was inactivated at 60 degrees C. Its molecular weight was estimated by Sephadex gel filtration to be approximately 9 times 10(4) daltons. Partially purified LT, in titration studies, showed single hit kinetics. It also inhibited L cell proliferation at low concentration without significant killing effect. The heat inactivation curves of both cytotoxic and proliferation inhibitory activities were the same, suggesting that these two activities may be caused by the same molecule. However, it had almost no detectable effect on the DNA synthesis of rat lymph node cells stimulated with phytohemagglutinin (PHA), suggesting that lymphocytes, at least those which respond to HA, are rather resistant to LT. It is suggested that activities described as "proliferation inhibitory factor" and "cloning inhibitory factor" by others may represent the activity of dilute LT. The "inhibitor of DNA synthesis" is distinct in molecular character, range of target cells, and target cell kinetics from LT.

Animals↗