Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of urethan on the induction of ornithine decarboxylase in the early stage of the regeneration of rat liver was studied. The induced activity of ornithine decarboxylase was suppressed by administration of urethan immediately after partial hepatectomy. Although ornithine decarboxylase was induced biphasically by partial hepatectomy, a single intraperitoneal injection of urethan resulted in the reduction of both phases. However, the ornithine decarboxylase activity induced by glucocorticoids and growth hormone was not suppressed by urethan. The increased level of 3',5'-cyclic adenosine monophosphate induced by partial hepatectomy was also reduced by urethan and this suppression was proportional to the suppression of ornithine decarboxylase activity. Reversal of the urethan-induced suppression of ornithine decarboxylase by administration of dibutyryl 3',5'-cyclic adenosine monophosphate was also observed.
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PMID:Effect of urethan on the induction of ornithine decarboxylase in regenerating rat liver. 21 56

Ornithine decarboxylase activity (ODC) increased about 7 fold 6--8 h following 10mM asparagine (ASN) addition to confluent cultures that had been previously serum deprived and then placed in a salts/glucose medium. Optimal concentrations of dibutyryl cAMP (dB cAMP) when incubated with the ASN caused up to a 50 fold increase in the activity of this enzyme after 7--8 h. The enhancement of ODC activity by ASN and dB cAMP was not sensitive to continuous (0--7 h) treatment with actinomycin D but similar treatment with cycloheximide depressed enzyme activity 40--60%. The synergistic stimulation of ODC activity by dB cAMP added with ASN was dose dependent and the dB cAMP stimulation of ODC activity displayed an absolute requirement for ASN when cells were maintained in the salts/glucose medium. The addition of dB cAMP always further enhanced ODC activity above the levels produced by addition of various levels of ASN (1 to 40mM) to the salts/glucose medium. Other agents which elevated cAMP levels such as 1-methyl-3-isobutylxanthine (IBMX) also enhanced ODC activity when administered with ASN. Additionally, treatment with sodium butyrate at concentrations ranging from 0.001mM to 5.0mM did not elevate ODC activity above the activity obtained with ASN alone. Addition of dB cAMP at various times after placing cells in salts/glucose medium with ASN further stimulated ODC activity only when added during the first 3-4 h. These results demonstrate the involvement of cAMP in the ASN mediated stimulation of ODC activity using cells maintained in a salts/glucose medium.
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PMID:Cyclic AMP-dependent regulation of ornithine decarboxylase activity in Chinese hamster ovary cells maintained with a salts/glucose medium. 21 73

Tumor promoters and anti-promoters have been shown to modify the induction of ornithine decarboxylase, the production of plasminogen activator, and the recovery of induced mutations. Data were presented to show that the recovery of mutagen-induced ouabain-resistant mutations in cultured Chinese hamster cells is increased with a tumor-promoter treatment and reduced by anti-promoter treatments. The results suggest that many induced mutations can either be repressed or derepressed by promoters or anti-promoters. The results also support the hypothesis that tumor initiation is due to a mutagenic event, while tumor promotion is the result of an epigenetic process involving cyclic nucleotide modulation of gene expression.
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PMID:In vitro assay for tumor promoters and anti-promoters. 21 6

Human cytomegalovirus (HCMV) infection of low serum-arrested confluent whole human embryo (Flow 5000) cells markedly stimulated ornithine decarboxylase (ODC) activity. Increased ODC activity was apparent by 12 h post-infection. The capacity of HCMV to stimulate ODC was: (1) dependent upon multiplicity of infection; (2) eliminated when the virus was neutralized with specific antiserum; and (3) sensitive to ultraviolet irradiation. Virus-mediated induction, in contrast to high serum induction of ODC, was not subject to inhibition by polyamines added to the growth medium. Phosphonoacetic acid (PAA) which blocks HCMV replication by inhibiting the activity of HCMV-specific DNA polymerase and which does not prevent HCMV induced stimulation of cell DNA synthesis, reversibly inhibited HCMV-induced stimulation of ODC activity by 74%. Studies with PAA indicated that HCMV-induced stimulation of ODC activity is independent of cell DNA synthesis and that the mechanism regulating virus-induced stimulation may be related to the HCMV-specific DNA polymerase.
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PMID:Stimulation of ornithine decarboxylase by human cytomegalovirus. 21 56

The level of luliberin, the luteinizing hormone-releasing hormone (LH-RH), and the possibility of the hormonal control of metabolic and biosynthetic processes in the heart were studied. It was shown that the rat heart contains a factor, which is immunochemically and chromatographically related to LH-RH (19--46 picograms per organ). Intraperitoneal injection of LH-RH increases the activities of phosphorylase A and ornithine decarboxylase and the concentration of 3',5'-AMP and potentiates the stimulating effect of adrenaline on ornithine decarboxylase.
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PMID:[Cardiotropic effects of luliberin. Effects of luliberin on the activities of phosphorylase A and ornithine decarboxylase and concentration of 3', 5'-AMP]. 21 12

After a single injection of diethylnitrosamine (200 mg/kg), there was a rapid increase in the activity ratio of hepatic cyclic adenosine 3':5'-monophosphate (cyclic AMP)-dependent protein kinase (within 1 hr) followed by the induction of ornithine decarboxylase which was detectable by 3 hr. Both the cyclic AMP-dependent protein kinase activity ratio and the activity of ornithine decarboxylase were significantly elevated above controls for 7 days following the administration of diethylnitrosamine. A single noncarcinogenic dose of diethylnitrosamine (25 mg/kg) did not increase the cyclic AMP-dependent protein kinase activity ratio or induce ornithine decarboxylase activity at 24 hr postadministration. However, serial administration of diethylnitrosamine (25 mg/kg) for 4 or 7 days resulted in an increased activity ratio of cyclic AMP-dependent protein kinase and increased ornithine decarboxylase activity. This is the first report of a prolonged increase in both the activity ratio of hepatic cyclic AMP-dependent protein kinase and the activity of ornithine decarboxylase in response to a single carcinogenic dose of diethylnitrosamine.
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PMID:Prolonged induction of hepatic ornithine decarboxylase and its relation to cyclic adenosine 3':5'-monophosphate-dependent protein kinase activation after a single administration of diethylnitrosamine. 22 43

The activities of ornithine and S-adenosyl-L-methionine decarboxylase were assayed in the thymuses of adult rats killed at 7-day intervals up to 6 wk after either pinealectomy or sham pinealectomy. The absence of the pineal gland markedly influenced the ornithine decarboxylase activity in the thymus, in which the level of the enzyme was decreased permanently by the 4th wk after the operation (P less than 0.05). The time course of the changes in S-adenosyl-L-methionine decarboxylase activity in the thymus during the entire period investigated was also significantly (P less than 0.05) modified by pinealectomy but did not show any stable trend. Adrenalectomy significantly raised (P less than 0.001) for ornithine decarboxylase; P less than 0.01 for S-adenosyl-L-methionine decarboxylase) the basal levels of the thymic biosynthetic polyamine decarboxylases. A pharmacological dose of corticosterone or cortisol produced a rapid and significant decrease in ornithine and S-adenosyl-L-methionine decarboxylase activities (P less than 0.02) in the thymus, whereas the injection of either D-aldosterone or ACTH was ineffective. Therefore, the thymic biosynthetic polyamine decarboxylases that in this organ are known to be located only in the lymphocytes appear to be regulated in opposing ways by the pineal gland and by the adrenal cortex.
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PMID:Endocrine regulation of thymic biosynthetic polyamine decarboxylases in adult rat. 22 48

The effect of different phorbol esters and of mechanical treatment on the activity of ornithine decarboxylase in mouse epidermis in vivo was investigated. The strong promoter 12-O-tetradecanoylphorbol-13-acetate as well as the weak promoters phorbol dibenzoate and the 12-O-tetradecanoylphorbol-13-acetate analog 12-O-tetradeca-2-cis, 4-trans-6,8-tetraenoylphorobol-13-acetate strongly increased the activity of the enzyme and the intraepidermal level of putrescine, with a maximum at 5 hr after application, when applied in doses which evoke comparable proliferative and irritant responses in skin. The hyperplasiogenic but nonirritant and almost nonpromoting 4-O-methyl ether of 12-O-tetradecanoylphorbol-13-acetate did not show such effects. Mechanical removal of the uppermost horny layer led to a considerable increase of ornithine decarboxylase activity after 4 to 8 hr, while skin massage showed only a minute effect under conditions in which both treatments exhibit about the same mitogenic efficiency. Neither manipulation promotes tumor development. After skin massage, the induction of ornithine decarboxylase was influenced neither by treatments which alter the cyclic adenosine 3',5'-monophosphate level in epidermis (inhibition of phosphodiesterase, beta-adrenergic stimulation, and injection of dibutyryl cyclic adenosine 3',5'-monophosphate) nor by injection of epidermal G1 chalone. The results indicate that no clear-cut correlation exists between epithelial cell proliferation, development of hyperplasia, and tumor promotion on the one hand and an activation of epidermal ornithine decarboxylase on the other.
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PMID:Ornithine decarboxylase activity, cell proliferation, and tumor promotion in mouse epidermis in vivo. 22 17

Cholera toxin activated beef thyroid cyclic AMP-dependent protein kinase in a dose (0.2 to 8 microgram/ml)-related fashion. Thus, when beef thyroid slices were incubated with toxin (8 microgram/ml) for 90 minutes and then assayed for protein kinase, the activity ratio (i.e. -cyclic AMP/+cyclic AMP) increased from 0.32 +/- 0.02 to 0.77 +/- 0.06. The toxin (5 microgram/ml)-induced increase was abolished by inclusion of ganglioside GM1 in the incubation medium (I50, 0.7 microgram/ml), whereas, gangliosides GD1a and GT1 were without effect. In contrast, TSH-activated protein kinase was unaffected by ganglioside addition. Cholera toxin increased rat thyroid ornithine decarboxylase (ODC) activity in-vitro in a dose (0.1 to 10 microgram/ml)-related fashion [basal, 100 cf cholera toxin (10 microgram/ml), 1500 pmol 14CO2/g tissue/30 min]. The toxin (1 microgram/ml)- (but not TSH-) induced increase in ODC was abolished by inclusion of ganglioside Ga and GT1 were without effect. Cholera toxin stimulation of ODC was inhibited by indomethacin or iodide as are the stimulatory effects of TSH or dibutyryl cyclic AMP. These results demonstrate that although there are differences in the TSH and cholera toxin responses with respect to receptor (ganglioside) interaction, they nevertheless elicit similar intracellular responses in thyroid.
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PMID:Effects of cholera toxin on thyroid cyclic AMP-dependent protein kinase and ornithine decarboxylase activities. 22 45

1. The relationship between synthesis of putrescine, human cytomegalovirus DNA synthesis, cell DNA synthesis, and human cytomegalovirus replication has been studied. 2. Stimulation of ornithine decarboxylase activity by shifting low serum-arrested whole human embryo cells to high serum medium is inhibited more than 99% by 2.5 mM DL-alpha-difluoromethylornithine. The addition of DL-alpha-difluoromethylornithine to human cells arrested in low serum and subsequently stimulated by the addition of fresh high serum-containing medium, causes a greater percent inhibition of ornithine decarboxylase activity than when the drug is added to growing human cells. 3. Increased ornithine decarboxylase activity produced by infection of low serum-arrested human cells was inhibited by 5.0 mM of DL-alpha-difluoromethylornithine. However, at a concentration of 5.0 mM, neither DL-alpha-methylornithine nor DL-alpha-difluoromethylornithine affected human cytomegalovirus growth or was toxic to these cells. These data suggest that the increased putrescine synthesis produced by infection is not required for virus replication. 4. The addition of 5.0 mM DL-alpha-difluoromethylornithine had no effect on human cytomegalovirus DNA synthesis or human cytomegalovirus-induced stimulation of cell DNA synthesis. However, 5.0 mM DL-alpha-difluoromethylornithine significantly reduced the stimulation of cell DNA synthesis caused by treatment with mock infecting fluid.
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PMID:Inhibition of cytomegalovirus-stimulated human cell ornithine decarboxylase by alpha-difluoromethylornithine. 22 64


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