Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The transport mechanisms of O-(2-[(18)F]fluoroethyl)-L-tyrosine (FET) and 2-[(18)F]fluoro-L-tyrosine (FTyr) were compared to those of [(3)H]-Methyl-L-methionine (MET) in F98 rat glioma cells in vitro and by tumor imaging by ex vivo dual tracer autoradiography in F98 rat gliomas. Both, FET and FTyr exhibited similar transport characteristics in F98 glioma cells compared to MET, i.e. mainly a sodium dependent transport similar to system B(0,+) and sodium independent transport via system L. Radioactivity of FET in the acid precipitable fraction was <1% after 120 min incubation time while FTyr and MET exhibited a 15-18% incorporation into proteins. Comparison of FET and FTyr with MET uptake in F98 rat gliomas demonstrated a significant correlation of tumor to brain ratios and a similar intratumoral tracer distribution pattern.
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PMID:Comparison of fluorotyrosines and methionine uptake in F98 rat gliomas. 1283 87

O-(3-[(18)F]fluoropropyl)-L-tyrosine (FPT), an analogue of O-(2-[(18)F]fluoroethyl)-L-tyrosine (FET) as an amino acid tracer for tumor imaging with positron emission tomography (PET), was synthesized and evaluated. FPT was prepared by [(18)F]fluoropropylation of L-tyrosine in a two-step procedure. Biodistribution of FPT was determined in normal mice. FPT, FET and [(18)F]fluorine-2-deoxy-D-glucose (FDG) uptake studies were performed in mice bearing S18 fibrosarcoma and S. aureus-inoculated mice. Also, carcinoma-bearing mice and S. aureus-inoculated mice were imaged using FPT PET imaging compared with FET and FDG PET imaging. Synthesis of FPT was accomplished in about 60 min with an overall radiochemical yield of 25-30% (without decay correction) by manual operation. High uptake and long retention time of FPT and FET in kidney, liver, lung, blood, etc., and low uptake in brain were found. Furthermore, high FPT, FET and FDG uptake in tumor, and almost no FPT and FET uptake in inflammatory tissue, in contrast, high FDG uptake in inflammatory tissue, were observed. In conclusion, FPT is easy to prepare and superior to FDG in the differentiation of tumor and inflammation, and seems to be a potential amino acid tracer like FET for tumors imaging with PET.
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PMID:Synthesis and evaluation of O-(3-[18F]fluoropropyl)-L-tyrosine as an oncologic PET tracer. 1449 31

The absorbed and effective radiation doses resulting from the intravenous administration of the potential tumor-imaging PET radiopharmaceutical O-(3-[18F]fluoropropyl)-L-tyrosine (FPT) were estimated using biodistribution data from normal mice. The computer program 3P97 and the methodology recommended by MIRD were used to estimate the doses. The highest uptake of FPT was found in the urinary bladder and pancreas, followed by the liver and kidneys. The urinary bladder wall received the highest absorbed dose of 101.0 microGy/MBq for a 70-kg standard man. The brain received the lowest dose, 6.5 microGy/MBq. Other organs received doses in the range of 6.5-37.5 microGy/MBq. The effective dose was 18.2 microSv/MBq. The data show that a 370-MBq (10 mCi) injection of FPT would lead to an estimated effective dose of 6.7 mSv, which is in the accepted range of routine nuclear medicine investigations.
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PMID:Radiation dosimetry of O-(3-[18F]fluoropropyl)-L-tyrosine as oncologic PET tracer based on the mice distribution data. 1468 33

In AIDS, only a few types of tumors (mainly Kaposi's sarcoma and non-Hodgkin's lymphoma) increase in incidence despite global abnormalities in the immune system. In addition, the reason for the higher incidence of these tumors is not immunosuppression but other agents. This shows that the immune system has no absolute role in the prevention of tumors. Consequently, the fact that tumors do not develop in the majority of the population during their lifetime, indicates the existence of other defense system(s). We demonstrated previously that a mixture of 16 substances (selected experimentally out of 89 compounds of the circulatory system using the synergistic tumor cell-killing effect as criteria) had a cytotoxic effect (inducing apoptosis) in vitro and in vivo on tumor cell lines, but not on normal cells in vitro or animals. In our hypothesis these substances (L-tryptophan, L-tyrosine, L-methionine, L(-)malate, L-ascorbate, L-arginine, L-phenylalanine, L-histidine, 2-deoxy-D-ribose, d-biotin, pyridoxine, adenine, riboflavin, D(+)-mannose, orotate, and hippurate) are the active agents of a passive antitumor defense system (PADS). On the basis of the results, a tablet and a cream were developed, and an infusion is in preclinical phase. In this study we demonstrate that the above-mentioned substances can kill tumor cells when the experimental protocols, concentrations, and cell numbers are chosen to be comparable to the physiological conditions that exist in the living system when these substances fight against arising cancer cells. The results of our experiments demonstrate that the PADS really works in the human body.
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PMID:Experimental evidence for the existence of the passive antitumor defense system formed by the synergistic action of certain small substances of the circulatory system. 1496 7

We investigated the potential of O-[(11)C]methyl-L-tyrosine and O-[(18) F]fluoromethyl-L-tyrosine as positron-emitting tracers for tumor imaging. The two tracers had similar distribution patterns in rats bearing AH109A hepatoma, with pancreas and, on a lesser extent, AH109A showing the highest uptake. Uptake of both tracers in the AH109A and uptake ratios of AH109A-to-tissues (with the exception of AH109A-to-bone) gradually increased for 60 min. O-[(11)C]methyl-L-tyrosine was metabolically stable, whereas a negligible low amount of metabolites was observed for O-[(18)F]fluoromethyl-L-tyrosine. Both tracers showed the potential for tumor imaging.
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PMID:Evaluation of O-[11C]methyl-L-tyrosine and O-[18F]fluoromethyl-L-tyrosine as tumor imaging tracers by PET. 1501 84

We performed preclinical and clinical studies of O-[11C]methyl-L-tyrosine, a potential tracer for imaging amino acid transport of tumors by positron emission tomography (PET). Examinations of the radiation-absorbed dose by O-[11C]methyl-L-tyrosine and the acute toxicity and mutagenicity of O-methyl-L-tyrosine showed suitability of the tracer for clinical use. The whole-body imaging of monkeys and healthy humans by PET showed low uptake of O-[11C]methyl-L-tyrosine in all normal organs except for the urinary track and bladder, suggesting that the O-[11C]methyl-L-tyrosine PET has the potential for tumor imaging in the whole-body. Finally, the brain tumor imaging was preliminarily demonstrated.
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PMID:Preclinical and clinical evaluation of O-[11C]methyl-L-tyrosine for tumor imaging by positron emission tomography. 1582 Jul 60

Lung and prostate cancers are major health problems worldwide. Treatments with standard chemotherapy agents are relatively ineffective. Combination chemotherapy gives better treatment than a single agent because the drugs can inhibit the cancer in different pathways, but new therapeutic agents are needed for the treatment of both tumor types. Bradykinin (BK) antagonists offer advantages of combination therapy in one compound. These promising multitargeted anti-cancer compounds selectively stimulate apoptosis in cancers and also inhibit both angiogenesis and matrix metalloprotease (MMP) action in treated lung and prostate tumors in nude mice. The highly potent, metabolism-resistant bradykinin antagonist peptide dimer, B-9870 [SUIM-(DArg-Arg-Pro-Hyp-Gly-Igl-Ser-DIgl-Oic-Arg)2] (SUIM=suberimidyl; Hyp=4-hydroxyproline; Igl=alpha-(2-indanyl)glycine; Oic=octahydroindole-2-carboxylic acid) and its non-peptide mimetic, BKM-570 [2,3,4,5,6-pentafluorocinnamoyl-(o-2,6-dichlorobenzyl)-L-tyrosine-N-(4-amino-2,2,6,6-tetramethylpiperidyl)amide] are superior to the widely used but toxic chemotherapeutic drugs cisplatin and taxotere. In certain combinations, they act synergistically with standard anti-cancer drugs. Due to its structure and biological activity, BKM-570 is an attractive lead compound for derivatization and evaluation for lung and prostate cancer drugs.
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PMID:Combination cancer chemotherapy with one compound: pluripotent bradykinin antagonists. 1587 95

The new marine Halomonas sp. strain GWS-BW-H8hM (DSM 17996) was found to produce 3-(4'-hydroxyphenyl)-4-phenylpyrrole-2,5-dicarboxylic acid (HPPD-1) and 3,4-bis(4'-hydroxy- phenyl)pyrrole-2,5-dicarboxylic acid (HPPD-2). In initial cultivations using marine broth, only low contents of these compounds have been isolated. Improving the conditions and growing the strain on artificial seawater supplemented with tryptone 10 g l(-1), yeast extract 5 g l(-1), L-tyrosine 0.6 g l(-1), glycine 1 g l(-1), and glucose 6 g l(-1), the growth-associated HPPD-1 and HPPD-2 production of a 40-l batch cultivation reached the amounts of 47 mg l(-1) and 116 mg l(-1), respectively, after 65 h. Both compounds showed potent anti-tumor-promoting activities.
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PMID:Bioactive hydroxyphenylpyrrole-dicarboxylic acids from a new marine Halomonas sp.: Production and structure elucidation. 1664 32

Labeled amino acids (AA) are tumor tracers for use in nuclear medecine. O-(2-[(18)F]fluoroethyl)-L-tyrosine (FET) is transported by the L-system, known to function as an exchanger. In vitro utilization of FET, after a preload or prior to an afterload of non radioactive L-amino acids, was evaluated in order to measure the potential effects of AA content on the distinction between tumor and inflammatory lesions. Cellular uptake of FET was studied on rat osteosarcoma cells (ROS 17/2.8) and human leukocytes, initially loaded with nonradioactive L-tyrosine or L-methionine. FET efflux was evaluated from cells loaded with nonradioactive L-phenylalanine after tracer uptake. ROS 17/2.8 showed a higher sensitivity to preload and afterload effects on cellular FET content as compared with the leukocytes. We conclude that preload with L-tyrosine, prior to the administration of FET, may be a potential procedure to improve PET differentiation between tumor and inflammatory lesions.
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PMID:L-amino acid load to enhance PET differentiation between tumor and inflammation: an in vitro study on (18)F-FET uptake. 1719 98

Positron emission tomography (PET) using radiolabeled amino acids has shown great potential for more accurate diagnostics of cerebral gliomas. O-(2-[18F]Fluoroethyl)-L-tyrosine (FET) is a new tracer for PET which can be produced with high efficiency and distributed on a wide clinical scale in Germany. In a biopsy-controlled study, a significant improvement of the detection of true tumor extent of cerebral gliomas could be demonstrated by the combined use of FET PET and MRT in comparison with MRT alone. Advantages of FET PET are an improved guidance of biopsies, an improved planning of surgery and radiation therapy, and the differentiation of tumor recurrence from unspecific post-therapeutic tissue changes. Furthermore, FET PET appears to be particularly valuable in the prognosis of low-grade gliomas.
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PMID:[Improved diagnostics of cerebral gliomas using FET PET]. 1825 45


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