Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An enzyme-linked immunosorbent assay (ELISA) has been adapted to measure E. coli recA protein in the 1 to 10 ng range in whole-cell sonicates, membrane extracts, and osmotic shock fluid from 2 x 10(8) cells. The specific activity of recA protein is maintained at a relatively constant "basal' level (800 to 1,200 molecules per cell for wild-type E. coli in L-broth, salt-depleted broth and minimal media) during early-log and mid-log phase growth, but it increases by two- to ten-fold as the culture approaches saturation density. Nalidixate-induced levels are 20- to 50-fold higher, and 100-fold higher in a constitutive tif- spr- mutant. Induction of recA protein synthesis by nalidixic acid, which normally requires functional recBC enzyme, also occurs in recB- and recC- cells by pathways activated by mutation in the sbcA and sbcB indirect suppressors. In recB- sbcA- mutants, exonuclease VIII, the recE gene product, is required for induction of recA protein. Abolition of exonuclease I activity by mutation in sbcB allows induction of recA protein by nalidixate in recB- and recC- cells. Mutation in recF does not affect induction by nalidixate in RecBC+ cells, but it enables induction to occur in RecBC- cells, suggesting that recF gene product is involved in regulation of recA protein.
Mol Gen Genet 1982
PMID:Induction of E. coli recA protein via recBC and alternate pathways: quantitation by enzyme-linked immunosorbent assay (ELISA). 628 18

In the teleost retina, the photoreceptors and retinal pigment epithelium (RPE) undergo extensive movements (called retinomotor movements) in response to changes in light conditions and to an endogenous circadian rhythm. Photoreceptor movements serve to reposition the light-receptive outer segments and are effected by changes in inner segment length. Melanin granule movements within the RPE cells provide a movable melanin screen for rod outer segments. In the dark (night), cones elongate, rods contract, and pigment granules aggregate to the base of the RPE cell; in the light (day), these movements are reversed. We report here that treatments that elevate cytoplasmic cyclic adenosine 3',5'-monophosphate (cAMP) provoke retinomotor movements characteristic of nighttime dark adaptation, even in bright light at midday. To illustrate this response, we present a quantitative description of the effects of cyclic nucleotides on cone length in the green sunfish, Lepomis cyanellus. Cone elongation is induced when light-adapted retinas are exposed to exogenous cAMP analogues accompanied by phosphodiesterase (PDE) inhibitors (either by intraocular injection or in retinal organ culture). Cone movements is not affected by cyclic GMP analogies. Dose-response studies indicate that the extent, but not the rate, of cone elongation is proportional to the concentration of exogenous cAMP and analogue presented. As has been reported for other species, we find that levels of cAMP are significantly higher in dark- than in light-adapted green sunfish retinas. On the basis of these observations, we suggest that cAMP plays a role in the light and circadian regulation of teleost cone length.
J Gen Physiol 1982 May
PMID:Induction of dark-adaptive retinomotor movement (cell elongation) in teleost retinal cones by cyclic adenosine 3','5-monophosphate. 628 59

As a test of the hypothesis that cyclic nucleotides play a role in the regulation of retinomotor movements and disc shedding in the photoreceptor-pigment epithelial complex, we have used an in vitro eyecup preparation that sustains both disc shedding and cone retinomotor movements, Eyecups were prepared in white light from animals in which both shedding and cone movement had been blocked by 4 d of constant-light treatment. In eyecups incubated for 3 h in light, disc shedding was negligible and cones remained in the light-adapted (contracted) position. In eyecups incubated in darkness, however, a massive shedding response (dominated by rod photoreceptors) was induced, and at the same time cone photoreceptors elongated to their dark-adapted position. In eyecups incubated in light dbcAMP promoted cone elongation and thus mimicked darkness; the dbcAMP effect was potentiated by the phosphodiesterase inhibitors papaverine and 3-isobutylmethylxanthine. In eyecups incubated in darkness, on the other hand, both phosphodiesterase inhibitors and dbcAMP reduced the phagosome content of the pigment epithelium. The effects of dbcAMP on the cone elongation and rod shedding appear to be specific in that dbcGMP, adenosine, and adenosine 5'-monophosphate had no significant effect. Our results suggest that cAMP plays a role in the regulation of both retinomotor movements and disc shedding.
J Gen Physiol 1982 May
PMID:Effects of cyclic adenosine 3',5'-monophosphate on photoreceptor disc shedding and retinomotor movement. Inhibition of rod shedding and stimulation of cone elongation. 628 60

Brief, intracellularly injected pulses of cyclic GMP transiently depolarized toad retinal rod outer segments (ROS). The depolarization is antagonized by light, perhaps by the activation of phosphodiesterase (PDE), as shown in the biochemical studies of others. As measured by the antagonism of cyclic GMP pulses by light, PDE activity peaks after the peak of the receptor potential and has approximately the same recovery time as the membrane voltage after weak illumination, but recovers more slowly than the membrane potential after strong illumination, as sensitivity does in other preparations. A cyclic GMP pulse delivered just after the hyperpolarizing phase of the receptor potential tends to turn off the light response. The kinetics of recovery from this turnoff are similar to those of the initial phase of the receptor potential. This similarity suggests that the initial phase of the receptor potential is controlled by light-activated PDE. Both EGTA and saturating doses of cyclic GMP block the light response, but only cyclic GMP increases response latency, which suggests that if calcium is involved in transduction, it is controlled by the hydrolysis of cyclic GMP. After brief pulses of cyclic AMP, a new steady state of increased depolarization occasionally develops. The effects described above also occur under these conditions. The results are consistent with the hypothesis that light-activated hydrolysis of cGMP is an intermediary process in transduction.
J Gen Physiol 1982 Jul
PMID:Physiological evidence that light-mediated decrease in cyclic GMP is an intermediary process in retinal rod transduction. 628 36

Escherichia coli was grown in chemostat culture under glycerol-limited and ammonium-limited conditions at growth rates between 0.1 and 0.5 h-1. At steady state, the concentrations of cyclic AMP and cyclic GMP and the activities of four constitutive enzymes (glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, NADH oxidase and cyclic phosphodiesterase) were determined in the organism. Addition of exogenous cyclic AMP, cyclic GMP or phencyclidine perturbed the steady state and caused inhibition or stimulation of synthesis of phosphodiesterase and isocitrate dehydrogenase. A novel hypothesis is proposed to account for the ability of bacteria to regulate the synthesis of constitutive enzymes with cyclic nucleotides and possibly other small molecules.
J Gen Microbiol 1982 Apr
PMID:Cyclic AMP and cyclic GMP control of synthesis of constitutive enzymes in Escherichia coli. 628 44

1. Inhibition of platelet aggregation in vitro by pentoxifylline is rather weak, requiring about 1 mM pentoxifylline. Ex vivo, however, 15 mg/kg p.o. pentoxifylline exerts an enhanced release of prostacyclin-(PGI2)-like antiaggregatory activity from rat aortas. 2. Rat aorta incubated in vitro with 1 microM pentoxifylline releases antiaggregatory activity in a similar manner. The conversion of prostaglandin H2 to PGI2-like activity which is catalyzed by vascular microsomes, also is drastically stimulated in vitro by addition of 1 microM pentoxifylline. 3. Despite its inhibitory effect on platelet cyclic AMP-phosphodiesterase pentoxifylline in vitro without PGI2 has no essential effect on cyclic AMP levels in human platelets. However, in presence of PGI2, release of which probably is increased by pentoxifylline cyclic AMP level as well as inhibition of aggregation are enhanced by pentoxifylline above the effects of PGI2 itself.
Gen Pharmacol 1983
PMID:Reduced platelet aggregation by effects of pentoxifylline on vascular prostacyclin isomerase and platelet cyclic AMP. 629 55

ATP-dependent activation and deactivation of retinal rod outer segment phosphodiesterase is affected by calcium [Kawamura, S. and Bownds, M. D., J. Gen. Physiol. 77:571-591(1981)]. Our data demonstrate that although calmodulin has been found in rod outer segments [Liu, Y. P. and Schwartz, H., Biochim. Biophys. Acta 526:186-193(1978); Kohnken, R. E. et al, J. Biol. Chem. 256:12517-12522(1981)], this protein is not involved in calcium-dependent phosphodiesterase activation at light levels at which calcium clearly affects this enzyme's activity. Furthermore, calmodulin does not mediate the calcium-dependent deactivation of phosphodiesterase.
 ...
PMID:Calcium-dependent activation and deactivation of rod outer segment phosphodiesterase is calmodulin-independent. 630 54

The rat aorta responds biphasically to norepinephrine (NE) in calcium-free medium. The dissociable phasic and tonic components of the contraction are mediated through alpha-adrenoreceptor activation and mobilization of intracellular calcium. Dibutyryl-cAMP, papaverine (which inhibits cAMP phosphodiesterase and increases cAMP levels), bromo-cGMP, and sodium nitroprusside (which stimulates guanylate cyclase and increases cGMP levels) inhibited in a concentration-dependent manner the biphasic aortic contractions induced by NE in calcium-free medium. The log IC50 values of each of these smooth muscle relaxants for inhibition of the biphasic response to NE in calcium-free medium were very close to those required for inhibition of the contractions induced by NE or KCl in presence of extracellular calcium. The present findings indicate that the phasic and tonic components of NE-induced aortic contractions in calcium-free medium are subject to similar intracellular regulatory mechanisms by cyclic nucleotides at a step subsequent to alpha-adrenoreceptor occupancy by NE, since dibutyryl-cAMP and bromo-cGMP inhibited the tonic component of NE-induced contraction noncompetitively.
Gen Pharmacol 1983
PMID:Norepinephrine-induced contractions of the rat aorta in the absence of extracellular calcium--III. Effects of cyclic nucleotides. 631 28

The mechanism of interferon resistance was studied in two clones of Daudi cells, DIF2 and DIF3, which exhibit respectively moderate and pronounced resistance to both the antiviral and antiproliferative actions of human interferons-alpha and -beta. Clones DIF2 and DIF3 were found to possess specific high affinity interferon receptors similar to those of parental Daudi cells. However, DIF2 cells, which have a tetraploid karyotype, had approximately twice as many interferon-binding sites as either DIF3 or parental Daudi cells. One of the first detectable changes in Daudi cells following interferon treatment is a rapid increase in the intracellular concentration of cyclic GMP. No increase in cyclic GMP was observed in DIF2 or DIF3 cells treated with interferon-alpha. However, neither DIF2 nor DIF3 cells respond to sodium azide, a nonphysiological inducer of cyclic GMP. Interferon treatment was found to induce the production of 2'-5'-oligo-isoadenylate synthetase in DIF2 and DIF3 cells in a manner similar to parental Daudi cells, indicating that these cells possess functional interferon receptors. The levels of 2'-5'-oligo-isoadenylate synthetase and 2'-5' A phosphodiesterase activity were similar in all three cell lines, suggesting that the interferon resistance of clones DIF2 and DIF3 was not due to a deficiency of pp(A2' p)nA.
J Gen Virol 1983 Dec
PMID:Isolation of Daudi cells with reduced sensitivity to interferon. II. On the mechanisms of resistance. 631 52

The objective of the present study was to investigate the nature of the gonadotrophic stimulation of estradiol (E2) secretion by the ovary of a teleost fish in vitro. Spontaneous output of E2 decreased to a low baseline after 3 hr of superfusion and increased to a maximal level 2-3 hr after the introduction of homologous pituitary extract (T-PE) or human chorionic gonadotrophin into the superfusion system. Addition of the phosphodiesterase inhibitor, isobutyl methylxanthine (IBMX, 0.5 mM), into a closed-system incubation resulted in an augmented response of the ovary to either dibutyryl cyclic AMP or to T-PE. It is concluded that the gonadotrophic stimulation of E2 secretion from the ovary of Sarotherodon aureus is mediated by cyclic AMP as a second messenger. Purified carp GTH or ovine LH stimulated E2 secretion in vitro in a dose-dependent manner in the range 3-300 ng/ml. In order to examine the effect of ovarian stage on E2 secretion rate in response to a gonadotrophic stimulation, fish with regressed ovaries were transferred to 30 degrees for 29 days. Five fish were bled every 4 days and their ovaries were incubated individually with and without T-PE. A sevenfold increase in plasma E2 occurred 4 days after the transfer to 30 degrees, whereas the first significant increase in the gonadosomatic index (GSI) could be noted only on Day 12. Both the spontaneous secretion rate of E2 in vitro (E2 basal) and the secretion rate in response to T-PE (E2 max) increased together with the GSI throughout the experiment. However, the ratio E2 max/E2 basal, which reflects the capacity of the ovary to respond to the gonadotrophic stimulation, reached a peak on Day 16, when GSI was about 1. The ratio then declined and remained low until the end of the experiment. The early increase in plasma E2 can be explained by the elevated sensitivity of the ovary to GTH during the initial phase of the temperature-induced ovarian recrudescence. The high level of plasma E2 maintained from Day 16 on may be due to a spontaneous synthesis and secretion of the steroid, not necessarily controlled by GTH.
Gen Comp Endocrinol 1984 Feb
PMID:Stimulation in vitro of estradiol secretion by the ovary of a cichlid fish, Sarotherodon aureus. 632 Dec 93


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