Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In cultured normal rat liver epithelial cells, the specific activity and/or isozyme expression of NADH-diaphorase (NADH-D), pyruvate kinase (PK), glucose-6 phosphate dehydrogenase (G6PD), gamma-glutamyl transpeptidase (GGT), and alkaline phosphatase (AP) were markedly dependent on the growth state of the cultures. Proliferating, preconfluent cells had higher specific activities of PK, NADH-D, and G6PD but lower activities of GGT and AP than did the more stationary confluent cells. Addition of epidermal growth factor [EGF] to the media of proliferating cells enhanced the specific activities of PK, NADH-D, G6PD, GGT, and lactate dehydrogenase (LDH) of these cells, but the specific activity of AP was markedly depressed. The increase in activity of PK and GGT by EGF appeared to involve new protein synthesis, whereas the effect of EGF on AP appeared to involve the EGF-directed suppression of the synthesis of a form of AP that is produced exclusively by cells in confluent cultures. Furthermore, the preconfluent cells were more responsive to the action of EGF on AP than were confluent cells, i.e., the EGF-mediated decrease in AP activity was seen at lower concentration in preconfluent than in confluent cells. Paradoxically, confluent cells exhibited a two-to threefold higher capacity to bind [125 I]EGF because of an increase in surface receptor number. The results of this study indicate that enzymatic or other biochemical studies performed on cultured cells must take into account the growth-state of the cultures. EGF can modulate enzyme activity in growing and nongrowing cells; one effect of EGF is to maintain higher activity of glycolytic enzymes, suggesting that EGF or EGF-like factors may contribute to the high rate of glycolysis in certain neoplasms.
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PMID:The effects of epidermal growth factor and the state of confluence on enzymatic activities of cultured rat liver epithelial cells. 286 16

A cloned fetal Syrian hamster lung epithelial cell line (M3E3/C3) was used to compare the influence of two different culture conditions on the degree of cellular differentiation and susceptibility of the cells to undergo malignant transformation by a precarcinogen, benzo(a)pyrene. Conventional conditions consisted of growth medium containing Roswell Park Memorial Institute Medium 1640, pyruvate, and fetal bovine serum and a substratum of plastic. Complex conditions comprised the growth medium supplemented with insulin, hydrocortisone, estradiol, epidermal growth factor, transferrin, and cholera toxin and a substratum of collagen gel. Under the complex culture conditions, there was extensive development of endoplasmic reticulum and Golgi vesicles, whereas under conventional conditions these organelles were only minimally developed. This was correlated with 1.5-1.8 times enhancement of ethoxycoumarin deethylase and reduced nicotinamide adenine dinucleotide phosphate-dependent cytochrome c reductase activities. Decomposition of added benz(a)anthracene into water-soluble compounds increased with the period of incubation and reached about 40% of initial benz(a)anthracene (50 micrograms/10 ml/flask) at 48 h under the complex conditions, whereas under the conventional conditions only less than 4% decomposition occurred. Benzo(a)pyrene in the dose range 2-8 micrograms/ml was strongly cytotoxic and caused significant anchorage independent transformation only under complex culture conditions. Transformed cells produced tumors in two of four hamsters during 8 months following s.c. injection within 48 h of birth. These results suggest that the complex culture conditions predisposed the cloned fetal epithelial cells to malignant transformation by benzo(a)pyrene through stimulation of cellular differentiation and development of enzyme systems capable of activating it metabolically.
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PMID:Predisposition of cloned fetal hamster lung epithelial cells to transformation by a precarcinogen, benzo(a)pyrene, using growth hormone supplementation and collagen gel substratum. 380 97

Mammary explants from pregnant rats can be induced in regard to casein synthesis and alpha-lactalbumin activity when cultured in the presence of hydrocortisone, prolactin and levels of insulin approaching physiological concentrations. No detectable induction occurs in the absence of insulin. Although epidermal growth factor and multiplication stimulating activity, in the presence of hydrocortisone, can maintain the initial level of NADH-cytochrome c reductase as well as insulin, neither can substitute effectively for insulin in the induction of the milk proteins. Proinsulin, nerve growth factor, platelet-derived growth factor and fibroblast growth factor are also ineffective substitutes for insulin in this regard. Whereas prolonged tissue exposure to multiplication stimulating activity, hydrocortisone and prolactin does not result in induction of alpha-lactalbumin activity, subsequent addition of insulin leads to prompt response. The results suggest that the ability of insulin to function as a unique, essential factor in the induction of rat milk proteins is independent of its cell-maintenance activity. Thus, in addition to its well established functions in metabolic processes, insulin appears to play a vital role in certain developmental processes.
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PMID:A unique and essential role for insulin in the phenotypic expression of rat mammary epithelial cells unrelated to its function in cell maintenance. 635 73

The influence of cell density and epidermal growth factor (EGF) on the expression and inducibility of cytochrome P450 (CYP) genes of the CYP3A and CYP1A families in adult human hepatocytes in primary culture has been evaluated. Only when cultured at subconfluence and in the presence of EGF did hepatocytes exhibit a proliferative response, assessed by measuring DNA synthesis and cyclin A accumulation. In the absence of EGF, the accumulation of CYP3A4 and CYP1A2 messenger RNAs (mRNAs) in response to their respective inducers (rifampicin and dioxin) was dramatically decreased in subconfluent culture with respect to confluent cultures. The presence of EGF only slightly decreased the accumulation of these mRNAs in both confluent and subconfluent cultures. The accumulation of CYP2D6 and CYP2E1 proteins, which are constitutively expressed in confluent cultures, and the production of fibrinogen and apolipoprotein (Apo) B100 exhibited similar behavior, while nicotinamide adenine dinucleotide phosphate cytochrome c reductase activity was affected neither by cell density nor by EGF. In contrast, the accumulation of CYP1A1 mRNA in response to dioxin was similar in confluent and subconfluent cultures, irrespective of the presence of EGF. Interestingly, CYP3A7, a gene that is preferentially expressed in the fetal liver, was expressed constitutively neither in confluent nor in subconfluent cultures, irrespective of the presence of EGF. It is concluded that the loss of cell-cell contacts rather than the proliferative status of cells per se is responsible for the dramatic decrease in the expression of CYP genes, normally expressed in the adult human liver.
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PMID:Effect of cell density and epidermal growth factor on the inducible expression of CYP3A and CYP1A genes in human hepatocytes in primary culture. 914 35

Differentiation of PC12 cells has been quantified by measurement of neurite length. However, this procedure is not suitable for large numbers of samples, for example in 96-well tissue culture plates. For this reason, we established three simple and quantitative methods for nerve growth factor-induced differentiation of PC12 cells cultured in 96-well plates. Firstly, because neuronal markers, including neurofilament proteins and beta-tubulin isotype III, are increased during PC12 cell differentiation, we developed cell enzyme-linked immunoabsorbent assays (ELISA)-based procedures that measure the amount of these proteins. Secondly, because lactate dehydrogenase (LDH) is down-regulated and mitochondrial NADH-dehydrogenase activity is increased during PC12 cell differentiation, we established procedures to measure changes in LDH and NADH dehydrogenase. We found that the cell ELISA and cell counting assays could be used to determine the degree of PC12 cell differentiation caused by nerve growth factor, basic fibroblast growth factor and epidermal growth factor. However, neither LDH nor NADH-dehydrogenase activities changed during Thy-1 antibody-induced differentiation. These findings show that in addition to the cell ELISA procedures, the LDH and NADH-dehydrogenase procedures are useful for characterization of growth factor-induced PC12 cell differentiation.
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PMID:Assay-based quantitative analysis of PC12 cell differentiation. 1219 52

For centuries, edible bird's nest (EBN) has been consumed as a Chinese delicacy. In the past decades, numerous studies reported that water soluble extract of the EBN not only possessed epidermal growth factor, but also associated with a wide range of health-promoting effects. However, based on the traditional Chinese way of EBN preparation and consumption, the bioactive components should be originated from both its hot water soluble and insoluble fractions. Nevertheless, information on the hot water insoluble fraction (HWIF) of EBN is not currently available. In this study, peptides released from the HWIF of EBN under simulated gastro-intestinal conditions were identified for the first time by de novo sequencing using a combination of MALDI TOF/TOF MS and ESI-ion-trap MS/MS. The released peptides were found to share very high similarities to mucin, NADH dehydrogenase, acidic mammalian chitinase-like protein, immunoglobulin, proline-rich protein, von Willebrand factor and epidermal growth factor domain-containing protein.
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PMID:Identification of peptides released from hot water insoluble fraction of edible bird's nest under simulated gastro-intestinal conditions. 2954 34