1026
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Redman CM, Avellino G, Yu S. Secretion of proalbumin by canavanine-treated Hep-G2 cells. J Biol Chem 1983; 258:3446-52. [PMID: 6300044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The two processing sites in the conversion of preproalbumin to albumin are marked by arginine residues. Therefore, to study the mechanisms of albumin processing and secretion, the arginine residues of nascent albumin were replaced with canavanine by the incubation of Hep-G2 cells with this arginine analog. During a 4-h interval, canavanine inhibited (67%) the secretion of nascent albumin and increased the intracellular transit time of albumin secretion from 24 to 39 min. At 1 h, canavanine inhibited total protein synthesis by 19% and albumin synthesis by about 40%. Both the intracellular and secreted albumin produced by canavanine-treated cells were analyzed by DEAE-cellulose chromatography and were found to be more acidic than normal proalbumin and albumin. Further analysis on sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that the albumin produced and secreted by canavanine-treated cells appeared to have a larger molecular weight (by 4000) than serum albumin. The canavanine-treated cells were incubated with L-[3H]leucine and L-[3H]phenylalanine and the location of radioactive L-leucine and L-phenylalanine in the 30 NH2-terminal amino acid residues of secreted albumin was determined. The results indicated that canavanine-treated cells secreted proalbumin (79%) and also some fully processed albumin (21%). Preproalbumin was not secreted. Untreated Hep-G2 cells mostly secreted fully processed serum albumin (93%) with only traces of proalbumin (7%).
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1027
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1028
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Lannin DR, Yu S, McKhann CF. H-2 restriction of the T cell response to chemically induced tumors: evidence from F1 replaced by parent chimeras. THE JOURNAL OF IMMUNOLOGY 1982. [DOI: 10.4049/jimmunol.128.1.263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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1029
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Lannin DR, Yu S, McKhann CF. Thymus-dependent response: too little and too late for immunosurveillance. Transplantation 1982; 33:99-100. [PMID: 6977902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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1030
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Lannin DR, Yu S, McKhann CF. H-2 restriction of the T cell response to chemically induced tumors: evidence from F1 replaced by parent chimeras. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1982; 128:263-8. [PMID: 6459368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
MESH Headings
- Animals
- Antibodies
- Antigens, Neoplasm
- Binding, Competitive
- Cell Transformation, Neoplastic
- Cells, Cultured
- Crosses, Genetic
- Cytotoxicity, Immunologic
- Female
- Fibrosarcoma/chemically induced
- Fibrosarcoma/immunology
- H-2 Antigens/immunology
- Lymphocyte Culture Test, Mixed
- Methylcholanthrene
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Rabbits
- Spleen/immunology
- Whole-Body Irradiation
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1031
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Brendler T, Godefroy-Colburn T, Yu S, Thach RE. The role of mRNA competition in regulating translation. III. Comparison of in vitro and in vivo results. J Biol Chem 1981; 256:11755-61. [PMID: 6271760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Competition of encephalomyocarditis virus, reovirus, and L-cell mRNAs for a message-discriminatory component was studied in vitro. The data were analyzed qualitatively to determine the relative initiation efficiencies among the various mRNAs. The effects of potassium chloride concentration, magnesium acetate concentration, and m7G methylation on mRNA competition in vitro were also studied. These results were correlated with translation rates in vivo for the same mRNAs, to determine if the sites of competition in vitro and in vivo are the same. It was found that under a particular set of magnesium acetate and potassium chloride concentrations, the order of mRNA initiation efficiencies was the same both in vivo and in vitro, suggesting that the same limiting message-discriminatory factor is regulating initiation rates in both cases. This can only be accomplished in a competitive situation when RNA is in molar excess relative to the discriminatory component.
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1032
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Cherian MG, Yu S, Redman CM. Site of synthesis of metallothionein in rat liver. CANADIAN JOURNAL OF BIOCHEMISTRY 1981; 59:301-6. [PMID: 7248842 DOI: 10.1139/o81-041] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Free and membrane-attached polysomes were isolated from the liver of normal and cadmium-treated rats, and were translated using L-[35S]cysteine and a nuclease-treated reticulocyte lysate system. The translation products were analyzed for radioactive metallothionein by immunoprecipitation with antibodies to rat cadmium metallothionein followed by sodium dodecyl sulfate--polyacrylamide gel electrophoresis. In both normal and cadmium-treated rats, radioactive metallothionein was produced by free polysomes but not by membrane-attached polysomes. Cadmium treatment did not increase the in vitro ability of polysomes to synthesize metallothionein. As a control, the translation products of these two classes of polysomes were also analyzed for radioactive albumin and it was confirmed that membrane-attached polysomes produce albumin but do not synthesize metallothionein. The cell-free synthesis of metallothionein by free polysomes was also demonstrated by isolation of nascent metallothionein by Sephadex gel filtration and DEAE-cellulose chromatography. In adult rat liver there are two forms of metallothionein and both were produced in vitro by free polysomes.
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1033
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Lannin DR, Yu S, McKhann CF. T cells must recognize tumor antigen in association with self-MHC antigen. Transplant Proc 1981; 13:739-41. [PMID: 6168072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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1034
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Redman CM, Banerjee D, Yu S. The effect of colchicine on the synthesis and secretion of rat serum albumin. Methods Cell Biol 1981; 23:231-45. [PMID: 7035804 DOI: 10.1016/s0091-679x(08)61501-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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1035
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Yu S, Redman CM, Goldstein J, Blombäck B. Biosynthesis of canine fibrinogen: in vitro synthesis of A alpha, B beta and gamma precursor chains. Biochem Biophys Res Commun 1980; 96:1032-8. [PMID: 7437057 DOI: 10.1016/0006-291x(80)90056-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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1036
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Williamson JR, Tilton RG, Kilo C, Yu S. Immunofluorescent imaging of capillaries and pericytes in human skeletal muscle and retina. Microvasc Res 1980; 20:233-41. [PMID: 6448952 DOI: 10.1016/0026-2862(80)90010-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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1037
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Yu S, Lannin DR, Tsui-Collins AL, McKhann CF. Effect of cyclophosphamide on mice bearing methylcholanthrene-induced fibrosarcomas. Cancer Res 1980; 40:2756-61. [PMID: 7388826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Mice bearing large methylcholanthrene-induced fibrosarcomas lost the ability to respond in vitro to mitogen stimulation and to specifically neutralize autologous tumor cells in vivo. This depressed immune capability was due to active suppression, since spleen cells from advanced tumor-bearing mice could suppress the mitogen response of normal spleen cells and could inhibit tumor rejection when adoptively transferred to mice previously immunized against the tumor. Treatment with cyclophosphamide (CY) was found to affect the immune capability of the host, in addition to have a direct effect on the tumor. The number of cells in the lymph nodes and spleen, as well as their response to concanavalin A and lipopolysaccharide (but not phytohemagglutinin), decreased initially but returned to normal by Day 14. Most importantly, when CY was administered one day after tumor inoculation, the treated animals developed the ability to neutralize tumor at the same time as untreated controls but retained this capability as the tumors became advanced. Treatment with a single dose of CY as late as 11 or 20 days after tumor inoculation maintained or restored the tumor-neutralizing capacity of spleen cells. CY appears to alter the antitumor response of the host by inhibiting both cytotoxic and suppressor cells, but the cytotoxic cells recover rapidly, whereas the suppressor cells do not.
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1038
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Jen T, Yu S. 22 years (1954--1975) investigation of infant deaths in textile workers' families. Chin Med J (Engl) 1979; 92:107-12. [PMID: 105850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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1039
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Redman CM, Yu S, Banerjee D, Morris HP. In vitro synthesis and secretion of albumin by Morris hepatomas 5123C and 7800. Cancer Res 1979; 39:101-11. [PMID: 761180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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1040
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Subramanian C, Yu S, McKhann CF. Soluble suppressor factor from the spleens of tumor-bearing mice. Cancer Res 1978; 38:1996-2002. [PMID: 657137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Spleen cells from tumor-bearing mice when cultured for 3 to 5 days released a soluble factor into the media that suppressed the stimulation of lymph node and spleen cells by tumor antigen or mitogens. Spleens from mice bearing MC43 tumors for 14 days were capable of producing suppressor factor in vitro, while those from mice bearing the tumor for 10 days or less failed to do so. Lymph node cells from the same animals did not produce suppressor factor in vitro. The suppressor factor was produced by a nonadherent cell population, was heat stable, was lost on dialysis, and did not appear to be tumor antigen or thymidine.
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1041
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1042
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Burk MW, Yu S, Burk KR, McKhann CF. Stimulation of thymus- and bone marrow-derived lymphocytes by tumor cells in culture. Cancer Res 1977; 37:603-9. [PMID: 318923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In vitro lymphocyte stimulation by mitomycin-blocked tumor cells can be used to measure tumor-specific immune responses. In order to determine the responding cell type(s) in this reaction, lymph node and spleen cell populations were specifically depleted of thymus- or bone marrow-derived cells by the use of the appropriate antisera and complement or by immunoadsorption of the Fc receptor-bearing cells to antibody-coated sheep red blood cell monolayers. The compositions of both the original and the modified lymphocyte populations were determined by (a) viability counting following treatment with antisera and complement, (b) direct and indirect immunofluorescence, (c) antibody-coated erythrocyte rosette formation, and (d) response to thymus- and bone marrow-derived cell mitogens. In the lymph node cell populations, only the thymus-derived cells were stimulated by the tumor cells. However, both bone marrow- and thymus-derived cells from tumor-immune spleens underwent stimulation when exposed to tumor cells in culture.
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1043
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1044
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Burk MW, Yu S, McKhann CF. Tumor-specific immune responsiveness of the tumor-bearing host. ISRAEL JOURNAL OF MEDICAL SCIENCES 1976; 12:360-8. [PMID: 939694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In vitro lymphocyte stimulation by mitomycin-C-blocked tumor cells has been used to demonstrate tumor-specific antigens in methylcholanthrene-induced sarcomas and in syngeneic murine systems, and to follow the evolution of tumor immunity in the tumor-bearing state. Lymphocytes from normal mice, from mice bearing small methylcholanthrene-induced tumors (less than 1 cm in diameter) and from tumor-immunized mice (which had been sensitized by tumor cell inoculation and subsequent tumor (removal) were stimulated by mitomycin-C-blocked tumor cells to undergo increased DNA synthesis in culture. However, lymph node cells from mice with large methylcholanthrene-induced tumors (greater than 1 cm in diameter) had quite different characteristics. The background DNA-synthetic activity of lymph node cells from tumor-bearing mice was much higher than that of lymph node cells from normal mice or from preimmunized, non-tumor-bearing mice, and progressively increased with the duration of tumor-bearing and the size of the tumor. Lymph node cells from mice bearing large tumours appeared to be maximally stimulated by the tumor in vivo and were incapable of further stimulation by the same tumor cells in vitro, but exhibited normal responses to other antigens and nonspecific mitogens. Lymph node cells from mice bearing large tumors depleted of the adherent cells had lower background levels of DNA synthetic activity per 10(6) cells and underwent stimulation similarly to lymphoid cells from preimmunized, non-tumor-bearing mice. Spleen cells from mice bearing large tumors also had increased background levels of DNA synthetic activity, but contrary to the observations made with the lymph node cells, they were able to undergo further stimulation when cultured with the same tumor cells. Studies on the background incorporation of tritiated thymidine by lymph node cells from tumor-bearing mice revealed that the spontaneous uptake of reconstituted populations was nearly that of the original population and more than twice that of the arithmetical sum of the nonadherent and the adherent subpopulations. This was not found with normal lymph node cells or with spleen cells from normal or tumor-bearing mice. The differential effects observed with lymph node cells compared to spleen cells from tumor-bearing mice are emphasized and possible explanations for these findings are discussed.
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1045
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Yu S, Friedman Y, Richman R, Burke G. Altered thyroidal responsivity to thyrotropin induced by circulating thyroid hormones. A "short-loop" regulatory mechanism? J Clin Invest 1976; 57:745-55. [PMID: 175094 PMCID: PMC436710 DOI: 10.1172/jci108333] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We studied the effect of thyroid hormone administration on responsivity of murine thyroid to exogenous thyrotropin (TSH) in order to explore the possibility that the thyroid gland might be directly inhibited by its own hormones. In the rat both L-thyroxine (T4) and 3,5,3'-L-triiodothyronine (T3) pretreatment inhibited TSH-induced thyroidal ornithine decarboxylase (ODC) activity in vivo in a dose-related manner (half-maximal inhibition, 1.7 mug/rat and 0.6 mug/rat, respectively). Other structurally related compounds exhibited the following inhibitory potencies compared to T4: T3, 283%; triiodothyroacetic acid, 40%; D-T4, 18%; 3,5-L-diiodothyronine, 9%. Monoiodotyrosine, diiodotyrosine, and iodide were not inhibitory. The full inhibitory effect of T4 or T3 was observed when thyroid hormone was administered from 96 to 12 h before TSH and was also seen in hypophysectomized animals. Pretreatment with T4 or T3 in divided doses over 2 1/2 days inhibited TSH-induced increase in [1-14C]glucose oxidation to 14C02 and [3H] leucine incorporation into protein in rat thyroid. In the mouse T4 or T3 pretreatment (0.25-25 mug daily) caused dose-related inhibition of both thyroidal ODC activity and 131I release induced by TSH in vivo. In mice on a low-iodine diet (LID) but not in animals on a regular diet (RD) NaI pretreatment also blunted TSH-induced thyroidal ODC activation and 131I release. When LID or RD mice were pretreated with 12.5-125 mug of T4 or T3 over 2 1/2 days, TSH-induced in vitro stimulation of thyroid cyclic 3',5'-adenosine monophosphate formation was inhibited in a dose-related manner; NaI pretreatment was inhibitory in the LID mouse only. Prior administration of exogenous TSH blunted the activation of thyroid ODC and thyroid hormone release induced by subsequent TSH administration in rat and mouse. These studies indicate altered thyroid responsivity to TSH under the influence of circulating thyroid hormones and suggest the existence of a "short-loop" negative feedback regulating thyroid function.
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1046
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Richman R, Park S, Akbar M, Yu S, Burke G. Regulation of thyroid ornithine ornithine decarboxylase (ODC) by thyrotropin. I. The rat. Endocrinology 1975; 96:1403-12. [PMID: 165059 DOI: 10.1210/endo-96-6-1403] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We studied the effects of TSH on rat thyroid ornithine decarboxylase (ODC) activity. After 1 day of goitrogen treatment, there was an abrupt fall in serum triiodothyronine (T3) a rise in circulating TSH, and a dramatic increase in thyroid ODC activity. Despite the continued rise in TSH and progressive increase in thyroid gland size with further treatment, thyroid ODC activity declined on the third day and remained at submaximal levels. Thyroid ODC activity was also stimulated in a dose-related manner by administration of exogenous TSH. Little TSH effect was noted before 3 h. Maximal ODC activity occurred between 4 and 5 h. The TSH stimulation of ODC could be inhibited by pretreatment with actinomycin D or cycloheximide, suggesting that the increase in ODC activity requires new RNA and protein synthesis. Although pretreatment with agents that alter microtubule structure (e.g., colchicine and vinblastine) prevent stimulation of ODC activity by TSH, additional data suggest, but do not confirm, that hrmone secretion and ODC activation may be dissociable. Further studies were undertaken to determine whether cyclic AMP (cAMP) or prostaglandins played any role in the regulation of thyroidal ODC activity. Dibutyryl cAMP, alone, or together with aminophylline, did not stimulate thyroidal ODC activity in dosages which concomitantly stimulated adrenal enzyme activity. Likewise, prostaglandin E2 (PGE2) did not stimulate thyroidal ODC activity, but did stimulate adrenal enzyme activity in a dose-related manner. However, pre-treatment of rats with inhibitors of prostaglandin synthesis prevented the activation of thyroidal ODC BY TSH. One inhibitor, indomethacin, attenuated the TSH stimulation of enzyme activity in a dose-related manner. Indomethacin pretreatment also resulted in approximately a 10-fold decrease in thyroidal prostaglandin levels. Exogenous PGE9, in dosages as high as 500 pg, did not overcome the inhibitory effect of indomethacin on ODC activation. Although the precise role for endogenous prostaglandins remains to be defined, it does appear that a reduction in thyroidal prostaglandins prevents activation of the enzyme by TSH.
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1047
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Burk MW, Yu S, Ristow SS, McKhann CF. Refractoriness of lymph-node cells from tumour-bearing animals. Int J Cancer 1975; 15:99-108. [PMID: 47843 DOI: 10.1002/ijc.2910150112] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In vitro lymphocyte stimulation by mitomycin-C-blocked tumor cells has been used to demonstrate tumor-specific antigens in syngeneic murine systems and to follow the evolution of tumor immunity with the tumor-bearing state. Mitomycin-blocked tumor cells stimulated syngeneic lymphocytes from normal mice, from those bearing small tumors (less than 1 cm in diameter) and from tumor-immune mice, sensitized by tumor-cell inoculation and subsequent tumor removal, to undergo increased DNA synthesis as measured by the incorporation of tritiated thymidine. However, lymph-node cells from mice bearing tumors over 1 cm in diameter appeared to be maximally stimulated in vivo and incapable of further stimulation by the same tumor cells in vitro. This was reflected by the progressively increasing background levels of nucleic acid synthesis with the length of tumor-bearing and the size of the tumor. Although lymph-node cells from mice with large tumors did not respond to the same tumor cells in vitro, they did have normal responses to PHA. Within 7-14 days of surgical removal of the tumor, specific lymphocyte responsiveness and background activity returned to previous normal levels, but reinoculation with 10-6 tumor cells resulted in progressive tumor growth and loss of specific in vitro responsiveness when the second tumor had reached the critical size of 1 cm in diameter. Brief exposure of tumor-immune lymph-node cells to a soluble antigen extract of the same tumor resulted in a marked increase in DNA synthetic activity compared to that obtained after exposure to a different tumor extract, muscle extract or medium alone underwent stimulation when cultured with mitomycin-blocked tumor cells. However, normally responsive tumor-immune lymph-node cells, after brief exposure to a soluble antigen extract of the same tumor, initially underwent increased DNA synthesis, but were incapable of further stimulation by mitomycin-blocked tumor cells. Tumor antigen, alone or complexed with antibody, was also demonstrated in the sera of mice bearing large tumors and is thought to be responsible for the refractoriness of lymph-node cells from these mice to further stimulation in vitro. These experiments demonstrate that tumor size and the consequent antigen load to which the tumor-bearing animals is subjected have a profound effect on tumor-specific lymphocyte responsiveness.
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1048
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Yu S, Bichsel H. A possible mechanism for reduced radiation damage by relativistic charged particles, e.g. in electron microscopy. Phys Med Biol 1974. [DOI: 10.1088/0031-9155/19/2/087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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1049
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Baker M, Yu S, Coon DD. Twist Relation, Third Factorization, and the General Vertex in a Dual Multiparticle Theory with Nonlinear Trajectories. Int J Clin Exp Med 1972. [DOI: 10.1103/physrevd.6.538] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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1050
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Yu S, Baker M, Coon DD. First and Second Factorization in a Dual Multiparticle Theory with Nonlinear Trajectories. Int J Clin Exp Med 1972. [DOI: 10.1103/physrevd.5.3108] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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