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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was designed to evaluate in a syngeneic system the longterm effect of dietary reduction of each of three essential amino acids on carcinogenesis with methylcholanthrene (MCA) and immunity to a transplanted MCA tumor. Inbred mice were provided a standard amino acid diet or a diet deficient in isoleucine, leucine, or phenylalanine-tyrosine. In the carcinogenesis experiment, MCA pellets were implanted in each mouse and weekly records were maintained of body weight, tumor incidence, tumor size, and death rate. Mice in the immunity study were inoculated with syngeneic tumor cells; tumors were excised when the largest tumor in the control group reached 12 mm and each animal then received a second challenge of tumor cells. The available data suggest that (1) restriction of the selected amino acids does not inhibit chemical carcinogenesis with MCA, (2) phenylalanine-tyrosine deficiency may actually enhance chemical carcinogenesis with MCA, and (3) selected essential amino acid deficiencies do not enhance immunity to a transplanted MCA tumor.
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PMID:Effects of essential amino acid deficiencies on syngeneic tumor immunity and carcinogenesis in mice. 68 45

The transfer RNA separation by chromatography on strong-base polystyrene exchange materials is examined and compared with the widely used reversed-phase chromatography. Results indicate important differences in some transfer RNA (tRNA) elution patterns by the anion-exchange chromatography, as compared with the reversed-phase chromatography. Transfer RNAs containing hydrophobic groups are adsorbed more strongly. The anion exchanger has twice the number of theoretical plates. Single peaks of tRNA2Glu and tRNA1Phe obtained from the reversed-phase column give multiple peaks only polystyrene anion-exchange chromatography. All six leucine tRNAs (Escherichia coli) and differences in tRNA populations synthesized during early and late stages of the dividing lymphocytes from normal human blood can be characterized by the anion-exchange chromatography. Different separation profiles are obtained by two separation systems for tyrosine tRNAs from mouse liver and mouse-plasma-cell tumor. The results indicate that, in contrast to the reversed-phase chromatography, strong-base-polystyrene anion-exchange chromatography is capable of separating tRNAs with minor structlral differences.
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PMID:Separation of transfer ribonucleic acids on polystyrene anion exchangers. 79 62

We describe a method for determining those urinary total phenolic compounds that are tyrosine analogs or metabolites, such as thyroxine and catecholamines. The urine sample, 4-aminoantipyrine in carbonate-bicarbonate buffer, and potassium ferricyanide solution are mixed and the quinoneimine dye that forms is measured at 500 nm. Some cases of hyperthyroidism, diabetes mellitus, nephrosis, obesity, hypertension, or catecholamine-producing tumor showed above-normal values, so that this determination seems useful as a screening test for these disorders.
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PMID:Determination of urinary total phenolic compounds with use of 4-aminoantipyrine: suggested screening test for hyperthyroidism and for catecholamine-producing tumor. 91 84

The biochemistry and secretory characteristics of a transplantable rat pheochromocytoma have been studied. This tumor possesses the enzyme required for the biosynthesis of norepinephrine from tyrosine, and stores large amounts of norepinephrine (33 +/- 3 nmol/mg of protein). The tumor does not have detectable levels of noradrenalin N-methyltransferase, nor does it contain significant amounts of epinephrine. Approximately two-thirds of the catecholamine content, and one-half of the dopamine beta-monoxygenase activity in the tumor can be isolated in a granule fraction by sedimentation. This granule fraction also contains ATP; the molar ratio of catecholamine to ATP in this granule fraction (5.6 +/- 0.9) is similar to that found in granules prepared from normal adrenal glands. Cell suspensions were prepared by mechanical disruption of the tumor. Incubation of these cell suspensions in media containing 56 mM K+, or the divalant cation ionophores, lasolocid or A23187, leads to the release of catecholamine from these cells. The cells do not secrete catecholamine in response to acetycholine. Catecholamine release induced by 56 mM K+ appears to be by exocytosis, since this release is dependent upon extracellular Ca++, and is accompanied by the release of dopamine beta-monooxygenase, but not of lactate dehydrogenase, from the cells. The mechanism by which the ionophores stimulate catecholamine secretion has not been established.
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PMID:Studies of a transplantable rat pheochromocytoma: biochemical characterization and catecholamine secretion. 93 94

Yeast phenylalanine ammonia-lyase (EC 4.3.1.5) catalyzes the deamination of L-phenylalanine to form trans-cinnamic acid and tyrosine to trans-coumaric acid. Maximal enzyme activity in Rhodotorula glutinis (2 units/g, wet weight, of yeast) was induced in late-log phase (12 to 14 hours) of growth in a culture medium containing 1.0% malt extract, 0.1% yeast extract, and 0.1% L-phenylalanine. A highly purified enzyme was obtained by fractionation with ammonium sulfate and sodium citrate followed by chromatography on DEAE-cellulose and Sephadex G-200. The active preparation yielded a major component on three different polyacrylamide gel electrophoretic systems. Antisera to phenylalanine ammonia-lyase was raised in rabbits and detected by double immunodiffusion. The antigen-antibody complex was enzymatically active in vitro. The biological half-life of the enzyme was approximately 21 hours in several mammalian species (mice without and with BW10232 adenocarcinoma and B16 melanoma, rats, and monkeys) after a single injection; however, upon repeated administration, phenylalanine ammonia-lyase had a much shorter biological half-life. The onset of rapid clearance occurred earlier in tumor-bearing than in nontumor-bearing mice indicating a direct or indirect influence by the tumor on the biological half-life of phenylalanine ammonia-lyase.
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PMID:Phenylalanine ammonia-lyase. Induction and purification from yeast and clearance in mammals. 98 16

We evaluated the effect of intravenous (i.v.) glucose on the plasma tryptophan (TRP) and tyrosine (TYR) concentration of 12 normal subjects, six patients with carcinoid tumors and the carcinoid syndrome (carcinoid syndrome), and five patients with carcinoid tumors without the carcinoid syndrome (tumor.) Following i.v. glucose administration, the plasma Trp concentration of the normal subjects and the tumor patients incresed, while the plasma Trp concentration of the carcinoid syndrome patients decreased. Following i.v. glucose administration, the plasma Tyr concentration of the normal subjects and the tumor patients decreased, while the plasma Tyr concentration of the carcinoid syndrome patients did not change. The response to i.v. insulin differed in some respects from the response to i.v. glucose: the plasma Trp of normal subjects did not change while the plasma Trp of carcinoid syndrome patients decreased; the plasma Tyr of the normal subjects increased while the plasma Tyr concentration of the carcinoid syndrome patients did not change. The carcinoid syndrome patients had high serum serotonin concentrations and impaired glucose tolerance and insulin secretion as compared to both normal subjects and tumor patients. We conclude that under appropriate experimental conditions, glucose administration can increase the plasma Trp concentration of normal human subjects.
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PMID:Effect of intravenous glucose and insulin on plasma tryptophan and tyrosine concentrations in normal subjects and patients with carcinoid tumors. 124 11

We have established the human nck sequence as a new oncogene. Nck encodes one SH2 and three SH3 domains, the Src homology motifs found in nonreceptor tyrosine kinases, Ras GTPase-activating protein, phosphatidylinositol 3-kinase, and phospholipase C-gamma. Overexpression of human nck in 3Y1 rat fibroblasts results in transformation as judged by alteration of cell morphology, colony formation in soft agar, and tumor formation in nude BALB/c mice. However, overexpression of nck does not induce detectable elevation of the phosphotyrosine content of specific proteins, as is observed for v-crk, another SH2/SH3-containing oncogene. Despite this fact, we demonstrate that Nck retains the ability to bind tyrosine phosphorylated proteins in vitro, using a fusion protein of Nck with glutathione-S-transferase (GST). Moreover, when incubated with lysates prepared from v-src-transformed 3Y1 cells or the nck-overexpressing cell lines, GST-Nck binds to both p60v-src and serine/threonine kinases, respectively. Although phosphotyrosine levels are not elevated in the nck-expressing fibroblasts, vanadate treatment of these cells results in a phosphotyrosine pattern that is altered from the parental 3Y1 pattern, suggestive of a perturbation of indigenous tyrosine kinase pathways. These results suggest the possibility that human nck induces transformation in 3Y1 fibroblasts by virtue of its altered affinity or specificity for the normal substrates of its rat homolog and that Nck may play a role in linking tyrosine and serine/threonine kinase pathways within the cell.
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PMID:The SH2- and SH3-containing Nck protein transforms mammalian fibroblasts in the absence of elevated phosphotyrosine levels. 128 Mar 26

Aggregating the receptor with high affinity for IgE (Fc epsilon RI) stimulates a variety of phenomena in mast cells. Previous efforts to reproduce some of these events in broken-cell preparations such as isolated membranes have had limited success, possibly because the phenomena being monitored were too distal from the initial events. One of the earliest responses is now known to be the phosphorylation of tyrosine residues on several proteins, including the beta and gamma subunits of Fc epsilon RI. We show that in cell sonicates or on partially purified membranes derived from tumor mast cells, aggregating Fc epsilon RI stimulates phosphorylation of receptor tyrosine residues. As in the intact cells, receptor-mediated phosphorylation occurs only on receptors that are themselves aggregated. Because even in the unfractionated sonicates the phosphorylation of other cellular components was not detectably enhanced, and because the evidence is against the receptor itself being a kinase, our results suggest that phosphorylation of Fc epsilon RI is one of the earliest events stimulated by the receptor--an event that can now be investigated on simpler biological preparations than previously available.
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PMID:Transmembrane signaling by the high-affinity IgE receptor on membrane preparations. 128 Aug 26

Octreotide is a synthetic analog of the peptide hormone somatostatin (SMS). A wide variety of tumors express enhanced numbers of SMS receptors, notably neuroendocrine tumors and lymphomas, but also some of the more common adenocarcinomas. Octreotide contains only eight amino acids, some of which are in the (D) configuration in order to enhance the stability of the molecule in vivo. Tyrosine and DTPA-containing analogs of octreotide have been synthesized and labeled with iodine-123 and indium-111, respectively, with the intention of targeting SMS receptor-containing tumors for diagnostic purposes. Both radiopharmaceuticals demonstrate a high sensitivity and specificity for these tumors, indicating a clinical role for these agents in management of these diseases. Lessons can be learned from the success of these agents when designing improved antibody-based molecules. Tumor uptake of radiolabeled octreotide is very rapid, occurring within minutes of administration. Blood clearance is also rapid, such that tumors are soon visible even in areas of high blood background. An interesting finding has been the differences between the pharmacokinetics of the iodinated and indium-labeled species. Although the majority of 123I-Tyr3-octreotide undergoes hepatobiliary excretion, 111In-DTPAPhe1-octreotide is eliminated predominantly by the kidneys. These results suggest that the smallest possible antibody-like tracers are likely to have advantages over native immunoglobulins and conventional Fab-like fragments.
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PMID:Radiolabeled octreotide. What lessons for antibody-mediated targeting? 128 34

The MCF-7 cell line is a hormone-responsive human breast-cancer cell line, which has been extensively used in studies of estrogen regulation of cell growth. These studies have indicated that the growth stimulation of the MCF-7 cells by estrogens may be effected by an autocrine mechanism involving several growth factors, such as EGF, TGF alpha and IGF-I and their receptors. We have amplified and cloned tyrosine-kinase-related sequences from the MCF-7 cell mRNA using the polymerase chain reaction and characterized the partial cDNAs obtained by nucleic acid sequencing. Nine tyrosine kinase cDNAs and one serine/threonine kinase cDNA were identified among the amplified sequences. Four different tyrosine kinase genes encoding receptors for fibroblast growth factors (FGFs) were found to be expressed by the MCF-7 cells. In addition, differences were observed in the expression of these members of FGF receptor family in different breast-cancer cells. A putative tyrosine-kinase receptor and a novel serine/threonine kinase were preferentially expressed in estrogen-responsive tumor cell lines. However, no estrogen-dependent regulation of any of the novel tyrosine-kinase receptor mRNAs was found in any of the cell lines including the MCF-7 or ZR-75-I cells, where the expression of the neu proto-oncogene mRNA was decreased during estrogen treatment. The expression of several FGF receptors by breast-cancer cells suggests that FGFs may be involved in their growth regulation and tumorigenesis.
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PMID:Analysis of tyrosine kinase mRNAs including four FGF receptor mRNAs expressed in MCF-7 breast-cancer cells. 131 Dec 87


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