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Biomedical subjects

T Kawamoto

Publications and source records attributed to T Kawamoto.

At least 361 records · Page 20Linked to original sources
PubMed1983

Development of a serum-free medium for growth of NS-1 mouse myeloma cells and its application to the isolation of NS-1 hybridomas.

In this study, we have devised a hormone-supplemented, lipid-enriched serum-free medium, designated KSLM, that supports the growth of NS-1 mouse myeloma cells and have studied its applicability to the efficient isolation of antibody-producing hybridomas formed from the fusion of NS-1 myeloma cells and spleen cells from immunized mice. Our results show that KSLM medium, when used in conjunction with our hybridization protocol, allowed for the isolation, in a reproducible manner, of antibody-secreting hybridomas. Moreover, the yield of antibody-producing hybridomas was similar in KSLM medium and serum-supplemented medium. Here, we also report on the adaptation of NS-1 myeloma cells to growth in lipid-deficient KSLM medium. The use of the adapted myeloma cells (NS-1-503), instead of NS-1 myeloma cells, in fusion experiments not only permitted the isolation of antibody-secreting hybridomas in lipid-free KSLM medium but also resulted in a higher yield of antibody-producing hybridomas in both complete KSLM medium and serum-supplemented medium.

Animals↗
PubMed1983

Growth stimulation of A431 cells by epidermal growth factor: identification of high-affinity receptors for epidermal growth factor by an anti-receptor monoclonal antibody.

Epidermal growth factor (EGF) at 3 nM maximally inhibits the proliferation of A431 epidermoid carcinoma cells. We show that at lower concentrations, in the range of 3-100 pM, EGF has a mitogenic effect on A431 cells. In the presence of 100 nM anti-EGF-receptor monoclonal IgG (designated 528), which inhibits A431 cell proliferation and blocks greater than 95% of EGF binding, EGF becomes mitogenic for A431 cells at concentrations up to 3 nM. These results suggest that a minor population of high-affinity EGF receptors may be involved in stimulation of A431 cell proliferation. Saturation binding assays with 125I-labeled EGF indicate that approximately equal to 0.1-0.2% of receptors for EGF are high-affinity receptors that bind EGF with an estimated Kd of 7 X 10(-11) M. This affinity is nearly 2 orders of magnitude higher than that of the remaining EGF receptors. Although A431 cell proliferation is maximally inhibited by nonsaturating amounts of EGF (3 nM), maximal inhibition by 528 IgG (approximately equal to 70% of maximal inhibition by EGF) requires saturating concentrations of antibody (approximately equal to 15 nM). Unlike EGF, rapid down-regulation is not observed with 528 IgG. These results indicate different mechanisms of growth inhibition of A431 cells by EGF and 528 IgG.

Animals↗
PubMed1983

[Uptake, elimination and metabolism of tetrachloroethylene in dogs].

Fifteen dogs were made to inhale tetrachloroethylene at concentrations of 700, 1,500, 2,000 ppm for one hour, and the changes in its concentrations in the expired air, the arterial blood, the venous blood and its metabolites (trichloroacetic acid (TCA), free-trichloroethanol (F-TCE) ) in the serum and the urine were measured from the beginning of exposure until two hours after it had been terminated. The results obtained were as follows. Levels of cumulative intake of tetrachloroethylene after one hour (i.e., at the termination of the inhalation) were 47 mg/kg for 700 ppm, 79 mg/kg for 1,500 ppm and 103 mg/kg for 2,000 ppm. Mean cumulative excretion ratio against the total intake two hours after the termination of the inhalation was 69% as the average for the three exposure levels. Mean ratio of the total absorption to the total intake for one hour was 23% as the average for the three levels. Using the above results, the authors did the multiple regression analysis of cumulative absorption (Y1) as well as cumulative excretion (Y2) taking two independent variables (X) and (Insp. or Z), which are as follows. a) During the exposure period, Y1: cumulative absorption (mg/kg), X1: exposure duration (min), Insp.: levels of solvent value in the inspired air (microgram/ml), log Y1 = -2.2819 + 0.5681 log X1 + 0.8232 log Insp. b) During the post exposure period, Y2: cumulative amounts of solvent excreted (mg/kg), X2: time in minutes after exposure end (min), Z2: cumulative absorption when exposure ended (mg/kg), log Y2 = -2.016 + 0.6976 log X2 + 0.7397 log Z2.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1983

Biological effects in vitro of monoclonal antibodies to human epidermal growth factor receptors.

Four mouse hybridomas secreting monoclonal immunoglobulin G (IgG) antibodies to epidermal growth factor (EGF) receptors of A431 cells were obtained independently from four fusion experiments. Three of the antibodies, 528 IgG, 225 IgG, and 579 IgG, inhibited the binding of [125I]EGF to A431 cells by at least 95%, and they competed with each other for binding to A431 cells. These antibodies bound to A431 cells, HeLa-S cells and human foreskin fibroblasts with dissociation constants in the range of Kd = 0.6 X 10(-9) to 2.5 X 10(-9) M. The fourth monoclonal antibody, 455 IgG, bound to A431 cells with lower affinity (Kd = 2.0 X 10(-8) M), and it had no effect on the binding of either EGF or the other antibodies to A431 cells. All four antibodies immunoprecipitated EGF receptors from Triton X-100 extracts of A431 membranes, but they were unable to bind to three rodent cell lines. In biological assays, none of the antibodies was able to mimic EGF. The antibodies which inhibited the binding of EGF blocked EGF-enhanced phosphorylation of A431 membrane proteins and inhibited EGF induced human fibroblast proliferation. These three antagonistic antibodies also partially reversed the inhibition of A431 growth by EGF. In contrast, 455 IgG had no effect on the early or delayed cellular responses to EGF.

Animals↗
PubMed1983

Apolipoproteins of high, low, and very low density lipoproteins in human bile.

We tested the hypothesis that apolipoproteins, the protein constituents of plasma lipoproteins, are secreted into bile. We examined human gallbladder bile obtained at surgery (N = 54) from subjects with (N = 44) and without (N = 10) gallstones and hepatic bile collected by T-tube drainage (N = 9) after cholecystectomy. Using specific radioimmunoassays for human apolipoproteins A-I and A-II, the major apoproteins of high density lipoproteins, for apolipoproteins C-II and C-III, major apoproteins of very low density lipoproteins, and for apolipoprotein B, the major apoprotein of low density lipoproteins, we found immunoreactivity for these five apolipoproteins in every bile sample studied in concentrations up to 10% of their plasma values. Using double immunodiffusion, we observed complete lines of identity between bile samples and purified apolipoproteins A-I, A-II, or C-II. Using molecular sieve chromatography, we found identical elution profiles for biliary apolipoproteins A-I, A-II and B and these same apolipoproteins purified from human plasma. When we added high density lipoproteins purified from human plasma to lipoprotein-free solutions perfusing isolated rat livers, we detected apolipoproteins A-I and A-II in bile. Similarly, when we added low density lipoproteins purified from human plasma to lipoprotein-free solutions perfusing isolated livers of rats treated with ethinyl estradiol in order to enhance hepatic uptake of low-density lipoproteins, we found apolipoprotein B in bile. These data indicate that apolipoproteins can be transported across the hepatocyte and secreted into bile.

Animals↗
PubMed1982

[Experimental examinations and toxicokinetic analysis of the absorption and excretion of 1,1,1-trichloroethane by the lung].

Of fifteen dogs each five of them inhaled 1,1,1-trichloroethane (1,1,1-TCE) at the levels of 700, 1500 and 2,000 ppm respectively for one hour. Changes in 1,1,1-TCE concentrations in the expired air, arterial blood and venous blood of dogs were measured from the beginning of exposure until one hour after the end of exposure. The results obtained were as follows. 1. Cumulative uptakes of 1,1,1-TCE in one hour exposure were 27.3 mg/kg at 700 ppm, 44.7 mg/kg at 1,500 ppm and 71.2 mg/kg at 2,000 ppm. 2. Excretion ratios of 1,1,1-TCE in one hour after the exposure were 66-71% at all the three levels of exposure. 3. During the exposure, highly significant negative correlation was seen between arterial/venous blood concentration ratio and expired/inspired air concentration ratio. In the post-exposure period, highly significant positive correlations were seen between expired air concentration and venous or arterial blood concentration. 4. The mean ratio of the total absorption value to the total inspired value was 14% at all the three levels of exposure. 5. From these results, the authors examined the multiple regression equations with two independent variables x and z which are shown as follows. a) During the exposure period, Y1: Cumulative absorption solvent value by the dog (mg/kg) X1: Time of exposure (min) Z1: Level of the solvent value in the ambient air (microgram/ml) log Y1 = -0.526 + 0.622 log X1 + 0.905 log Z1 b) Post exposure period, Y2: Cumulative excreted solvent value by the dog (mg/kg) X2: Time after the end of exposure (min) Z2: Cumulative absorbed solvent value by the dog at the end of exposure (mg/kg) log Y2 = -2.300 + 0.609 log X2 + 0.858 log Z2 We assumed that both equations are very fit and significant.

Animals↗