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[en] A radiochemical ligand binding assay for methotrexate is provided. A binder factor comprising a partially purified dihydrofolic acid reductase preparation is employed. The binder factor is conveniently prepared by homogenizing a factor containing animal organ such as liver, and extracting with isotonic saline and ammonium sulfate. A binder cofactor, NADPH2, is also employed in the binding reaction. The procedure contemplates both direct and sequential assay techniques, and it is not interfered with by vast excesses of many natural folate derivatives. 12 claims, 6 drawing figures
[en] Levels of glutathione (GSH) and two enzymes involved in GSH metabolism, glutathione reductase (GR) and glutathione-S-transferase(s) (GST), were measured in four SV40-transformed human fibroblast cell lines. MRC5-V1 and GM0637, derived from normal individuals, had mean GSH levels of 4.2 and 6.5 nmoles/106 cells, respectively. TAT2SF and AT5BIVA, both from ataxia-telangiectasia (A-T) patients, respectively had 6.5 and 4.2 nmol/106 cells, indicating that basal GSH levels were similar in A-T and normal cells. There was some variation in GST activity among the four cell lines but deficiency in this enzyme cannot be associated with radiosensitivity in A-T. When GR activity was measured, A-T cells had approximately 82 per cent of the mean normal activity. Though statistically significant, (P = 0.05), this small deficiency could be due to chance and is unlikely to be responsible for the radiosensitive phenotype of A-T. (author)
[en] Background and purpose: In malignant glioma the presence of the IDH1 mutation (IDH1R132H) is associated with better clinical outcome. However, it is unclear whether IDH1 mutation is associated with a less aggressive phenotype or directly linked to increased sensitivity to radiotherapy.
[en] Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are key metabolic enzymes that convert isocitrate to α-ketoglutarate. Somatic point mutations in IDH1/2 confer a gain-of-function in cancer cells, resulting in overproduction of an oncometabolite, 2-hydroxyglutarate (2HG). 2HG interferes with cellular metabolism and epigenetic regulation, contributing to oncogenesis. Given that IDH1 and IDH2 are attracting attention as promising therapeutic targets, better evaluation of the incidence of IDH1 and IDH2 mutations and 2HG level in human cancers is clinically important. This is the first study to assess their incidence in esophageal squamous cell carcinomas (ESCCs). First, we established pyrosequencing assays for IDH1 and IDH2 mutations and revealed that these mutations were absent in 10 ESCC cell lines and 96 ESCC tissues. Second, utilizing IDH1 and IDH2 overexpression vectors, we demonstrated that LC-MS/MS assays can accurately evaluate 2HG level and found that some ESCC cases presented a high level of 2HG. In conclusion, IDH1 or IDH2 mutations play a limited role in the development of ESCC. 2HG is potentially synthesized to high levels in the absence of IDH1 and IDH2 mutations, and this may correlate with progression of ESCCs.
[en] A porous organic-inorganic hybrid sol-gel carbon composite has been developed and used for surface covalent bonding of an enzyme for biosensing applications, illustrated by glucose oxidase (GOD). The composite comprises graphite powder, ferrocene, and an amino- and methyl-silicate backbone. The graphite powder provides the conductivity for the electrode and ferrocene acts as the mediator for signal transduction from the active center of the enzyme to the electron conductive surface. The presence of amine groups in the sol-gel silicate network allows for the covalent bonding sites for the enzyme via the carbodiimide reaction. The hydrophobicity and hydrophilicity properties of the electrode surface are controlled by the amine and methyl groups of the silicate network. Systematic optimization of the composite composition has been carried out and the performance of the glucose biosensor has been investigated. The optimal electrode gives a linear response range of 0.1-27 mM glucose with a sensitivity of 1.30 μA mM-1 and detection limit (S/N = 3) of 26 μM