Regulation of Thromboplastin Synthesis in Mouse Placental Cells In Vitro

1983 ◽  
Vol 50 (04) ◽  
pp. 831-834 ◽  
Author(s):  
Knut Dalaker ◽  
Hans Prydz
Keyword(s):  
Cyclic Amp ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effect ◽  
Low Concentrations ◽  
Placental Cells ◽  
Dose Dependent ◽  
Higher Doses ◽  
Dose Dependent Effect ◽  
Methyl Xanthine

SummaryMouse placental cells are probably constitutive producers of the thromboplastin apoprotein in vitro. The effect of cyclic AMP- elevating compounds on their expression of thromboplastin activity has been studied. Dibutyryl cyclic AMP, the phosphodiesterase inhibitor Ro 20-1724 and the adenyl cyclase stimulator forskolin all decrease the synthesis of thromboplastin. Prostaglandin E2 and the phosphodiesterase inhibitor butyl-methyl-xanthine have a biphasic dose dependent effect. A stimulation was observed at low concentrations, whereas higher doses decreased the synthesis of thromboplastin. Adrenaline had no effect. Combination of two compounds, each at maximally inhibiting concentration gave no significant additive inhibitory effect, showing that they probably act via the same pathway.

scholarly journals Use of forskolin to study the relationship between cyclic AMP formation and bone resorption in vitro

1986 ◽  
Vol 240 (2) ◽  
pp. 529-539 ◽  
Author(s):  
U H Lerner ◽  
B B Fredholm ◽  
M Ransjö
Keyword(s):  
Bone Resorption ◽  
Cyclic Amp ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effect ◽  
Cyclic Amp Accumulation ◽  
The Relationship ◽  
Dose Dependent ◽  
Old Mice ◽  
45Ca Release

The effect of the adenylate cyclase activator forskolin on bone resorption and cyclic AMP accumulation was studied in an organ-culture system by using calvarial bones from 6-7-day-old mice. Forskolin caused a rapid and fully reversible increase of cyclic AMP, which was maximal after 20-30 min. The phosphodiesterase inhibitor rolipram (30 mumol/l), enhanced the cyclic AMP response to forskolin (50 mumol/l) from a net cyclic AMP response of 1234 +/- 154 pmol/bone to 2854 +/- 193 pmol/bone (mean +/- S.E.M., n = 4). The cyclic AMP level in bones treated with forskolin (30 mumol/l) was significantly increased after 24 h of culture. Forskolin, at and above 0.3 mumol/l, in the absence and the presence of rolipram (30 mumol/l), caused a dose-dependent cyclic AMP accumulation with an calculated EC50 (concentration producing half-maximal stimulation) value at 8.3 mumol/l. In 24 h cultures forskolin inhibited spontaneous and PTH (parathyroid hormone)-stimulated 45Ca release with calculated IC50 (concentration producing half-maximal inhibition) values at 1.6 and 0.6 mumol/l respectively. Forskolin significantly inhibited the release of 3H from [3H]proline-labelled bones stimulated by PTH (10 nmol/l). The inhibitory effect by forskolin on PTH-stimulated 45Ca release was significant already after 3 h of culture. In 24 h cultures forskolin (3 mumol/l) significantly inhibited 45Ca release also from bones stimulated by prostaglandin E2 (1 mumol/l) and 1 alpha-hydroxycholecalciferol (0.1 mumol/l). The inhibitory effect of forskolin on spontaneous and PTH-stimulated 45Ca release was transient. A dose-dependent stimulation of basal 45Ca release was seen in 120 h cultures, at and above 3 nmol of forskolin/l, with a calculated EC50 value at 16 nmol/l. The stimulatory effect of forskolin (1 mumol/l) could be inhibited by calcitonin (0.1 unit/ml), but was insensitive to indomethacin (1 mumol/l). Forskolin increased the release of 3H from [3H]proline-labelled bones cultured for 120 h and decreased the amount of hydroxyproline in bones after culture. Forskolin inhibited PTH-stimulated release of Ca2+, Pi, beta-glucuronidase and beta-N-acetylglucosaminidase in 24 h cultures. In 120 h cultures forskolin stimulated the basal release of minerals and lysosomal enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

Dexamethasone and 8-bromo-cyclic AMP depress the incorporation of [3H]thymidine into mouse condylar cartilage by different pathways

1986 ◽  
Vol 109 (2) ◽  
pp. 209-213 ◽  
Author(s):  
Z. Kraiem ◽  
G. Maor ◽  
M. Silbermann
Keyword(s):  
Cyclic Amp ◽  
Thymidine Incorporation ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effect ◽  
Significant Inhibition ◽  
Condylar Cartilage ◽  
Camp Analogue ◽  
Dose Dependent Fashion ◽  
Cartilage Cells ◽  
Dose Dependent

ABSTRACT We examined whether cyclic AMP (cAMP) affects the incorporation of [3H]thymidine into cartilage cells and, if so, whether this action could be related to the inhibitory effect of glucocorticoid hormones on the growth of ossifying cartilage. Incorporation of [3H]thymidine into trichloroacetic acid-precipitable material by mouse cartilage was measured concomitantly with the concentration of cAMP. Dexamethasone (1 μmol/l) significantly (P < 0·05) depressed the incorporation of [3H]thymidine. The cAMP analogue 8-bromo-cAMP (0·01–1 mmol/l) also depressed the incorporation of the radionucleotide in a dose-dependent fashion. When various concentrations of 8-bromo-cAMP were added with dexamethasone (1 μmol/l), no apparent changes took place compared with the effect of dexamethasone alone. The phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (0·2-1 mmol/l) elicited an inhibitory effect on [3H]thymidine incorporation and a stimulatory influence on cartilage cAMP concentrations. Dexamethasone, at doses (0·01–1 μmol/l) causing significant inhibition of [3H]thymidine incorporation, failed to increase cartilage levels of cAMP. It seems, therefore, that the depressive effect of dexamethasone on [3H]thymidine incorporation in condylar cartilage is not mediated through an increase of cAMP in the tissue. J. Endocr. (1986) 109, 209–213

scholarly journals Nematicidal Activity of Monoterpenoids Against the Root-Knot Nematode Meloidogyne incognita

2010 ◽  
Vol 100 (2) ◽  
pp. 199-203 ◽  
Author(s):  
Sergio Echeverrigaray ◽  
Jucimar Zacaria ◽  
Ricardo Beltrão
Keyword(s):  
Meloidogyne Incognita ◽  
Nematicidal Activity ◽  
Root Knot Nematode ◽  
High Concentration ◽  
Tomato Plants ◽  
Pot Experiments ◽  
Low Concentrations ◽  
Dose Dependent ◽  
Dose Dependent Effect

Nematicidal activity of 22 monoterpenoids were evaluated in vitro and in pot experiments. Twenty of the twenty-two monoterpenoids significantly reduced hatching, and 11 reduced J2 mobility of the root-knot nematode Meloidogyne incognita at a concentration of 250 mg/liter. In general, compounds with hydroxyl and carbonyl groups exhibited higher nematicidal activity than other terpenoids. Borneol, carveol, citral, geraniol, and α-terpineol showed the highest nematicidal activity among the in vitro tested monoterpenoids. These compounds exhibited a dose dependent effect, and drastically reduced eggs hatching and J2 viability at low concentrations. These monoterpenoids, at 100 and 250 mg/kg concentration, diminished root galling of tomato plants in pot experiments. The results suggest that the selected monoterpenoids, and essential oils with high concentration of these compounds, are potential nematicides against Meloidogyne.

Theophylline Inhibition of Nucleoside Transport and its Relation to Cyclic AMP in Skeletal Muscle

1974 ◽  
Vol 52 (6) ◽  
pp. 1063-1073 ◽  
Author(s):  
Yin-Tak Woo ◽  
J. F. Manery ◽  
E. E. Dryden
Keyword(s):  
Skeletal Muscle ◽  
Cyclic Amp ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effect ◽  
Nucleoside Transport ◽  
Intracellular Uptake ◽  
Frog Skeletal Muscle ◽  
Dibutyryl Cyclic Amp ◽  
Cyclic Amp Phosphodiesterase ◽  
Dose Dependent

Using [14C]inosine and [3H]sorbitol, the effect of theophylline on inosine uptake was studied. Theophylline inhibited the intracellular uptake of inosine by isolated, frog skeletal muscle in a dose-dependent way. An inhibitory effect was also observed for the uptake of labelled adenosine, uridine, hypoxanthine, and adenine, but not for ribose. The inhibition was not readily reversible and was noncompetitive in nature. It was not secondary to the contracture of the muscle produced by the drug, because various treatments known to cause contracture had no effect on inosine transport. Also, papaverine (0.3 mM) significantly inhibited inosine transport without affecting the contractile properties of the muscle. Although theophylline is a cyclic AMP phosphodiesterase inhibitor, no relation could be found between inhibition of inosine uptake and cyclic AMP. N8,O2′-Dibutyryl cyclic AMP (1 mM) was ineffective. Though isoproterenol (10 μg/ml) increased the cyclic AMP concentrations in the muscle by 26-fold in the presence of theophylline and 3-fold in the absence of the drug, it did not influence inosine transport. Tracing the label into various intracellular nucleotides after incubation of the muscle with [14C]inosine suggested that theophylline inhibited inosine transport rather than inosine metabolism.

STIMULATION OF CORTISOL SECRETION IN VITRO FROM THE INTERRENAL TISSUE OF THE CICHLID FISH, SAROTHERODON AUREUS, BY ADRENOCORTICOTROPHIN OR CYCLIC AMP

1980 ◽  
Vol 86 (2) ◽  
pp. 269-277 ◽  
Author(s):  
Z. ILAN ◽  
Z. YARON
Keyword(s):  
Cyclic Amp ◽  
Cichlid Fish ◽  
Phosphodiesterase Inhibitor ◽  
Basal Medium ◽  
Cortisol Secretion ◽  
Superfusion System ◽  
Response Line ◽  
Dose Dependent ◽  
Stimulation Of

A superfusion system was developed in which secretion of cortisol from the interrenal tissue of Sarotherodon aureus could be stimulated by ACTH. Head kidneys from four fish were cut into fragments and superfused with Eagle's basal medium containing 4 mm-NaHCO3 and bovine serum albumin (50 mg/100 ml). The superfused medium was collected every 15 min before stimulation and every 5 min thereafter. Cortisol was measured in the medium by radioimmunoassay. The rate of cortisol secretion increased considerably after a 5 min pulse of 0·1 mu. porcine ACTH/ml, reaching a peak of 11·64 ± 2·40 (s.e.m.) ng/min (n = 5) after 20 min. In the subsequent 35 min the secretion rate decreased to a level of 0·49 ± 0·21 ng/min which was within the range of the baseline (0·2–0·7 ng/min). The amount of cortisol secreted by the superfused tissue in response to the corticotrophin, calculated from the area under the peak, was dose-dependent at the range of 0·06–273 mu. ACTH. Cortisol secretion in this system could also be stimulated by a crude pituitary extract from the same fish. Using the dose–response line, the adrenocorticotrophic activity in the pituitary gland of S. aureus was estimated as 0·2 i.u./g or 1·87 mu. per gland, in porcine ACTH equivalents. It was possible to substitute ACTH with dibutyryl cyclic AMP. The response of the interrenal tissue, i.e. the increase in secretion of cortisol, was dose-dependent at the range of 2–20 mmol/l. The response of the superfused interrenal tissue to ACTH could be extended by the addition of the synthetic phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (0·1 mmol/l), to the medium. These results indicated that the stimulation of cortisol secretion from the interrenal tissue of this fish by ACTH is, most probably, mediated by cyclic AMP as a second messenger.

Effect of Cyclic AMP and Cyclic GMP on Thromboplastin (Factor III) Synthesis in Human Monocytes In Vitro

1983 ◽  
Vol 50 (04) ◽  
pp. 804-809 ◽  
Author(s):  
Torstein Lyberg
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Immune Complexes ◽  
Phosphodiesterase Inhibitors ◽  
Inhibitory Effect ◽  
Intracellular Camp ◽  
Human Monocytes ◽  
Purified Protein Derivative ◽  
A 23187

SummaryHuman monocytes in vitro respond to various agents (immune complexes, lectins, endotoxin, the divalent ionophore A 23187, 12-0-tetradecanoyl-phorbol 13-acetate [TPA], purified protein derivative [PPD] of Bacille Calmette-Guerin) with an increased synthesis of the protein component of thromboplastin. The effect of cyclic AMP and cyclic GMP on this response has been studied. Dibutyryl-cyclic AMP, prostaglandin E1 and the phosphodiesterase inhibitors 3-butyl-1-methyl-xanthine (MIX) and rac -4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Ro 201724), separately and in combination have a pronounced inhibitory effect on the response to immune complexes and PPD, and a moderate effect on the response to endotoxin and lectins. The effect on TPA response and on the response to A 23187 was slight. Dibutyryl-cyclic GMP (1 mM) gave a slight inhibition of the TPA arid IC response, but had essentially no effect on the response to other inducers. The intracellular cAMP level increased when monocytes were incubated with IC, TPA or A 23187 followed by a decrease to basal levels within 1-2 hr, whereas lectin (PHA) and PPD did not induce such changes. The cAMP response to endotoxin varied. Stimulation with IC induced an increase in monocyte cGMP levels, whereas the other stimulants did not cause such changes.

Mechanism of the Antiplatelet Action of Dipyridamole in Whole Blood: Modulation of Adenosine Concentration and Activity

1986 ◽  
Vol 55 (01) ◽  
pp. 012-018 ◽  
Author(s):  
Paolo Gresele ◽  
Jef Arnout ◽  
Hans Deckmyn ◽  
Jos Vermylen
Keyword(s):  
Platelet Aggregation ◽  
Adenosine Receptor ◽  
Whole Blood ◽  
Blood Cells ◽  
Inhibitory Action ◽  
Phosphodiesterase Inhibitor ◽  
Inhibitory Effect ◽  
Adenosine Concentration ◽  
Pharmacological Studies

SummaryDipyridamole inhibits platelet aggregation in whole blood at lower concentrations than in plasma. The blood cells responsible for increased effectiveness in blood are the erythrocytes. Using the impedance aggregometer we have carried out a series of pharmacological studies in vitro to elucidate the mechanism of action of dipyridamole in whole blood. Adenosine deaminase, an enzyme breaking down adenosine, reverses the inhibitory action of dipyridamole. Two different adenosine receptor antagonists, 5’-deoxy-5’-methylthioadenosine and theophylline, also partially neutralize the activity of dipyridamole in blood. Enprofylline, a phosphodiesterase inhibitor with almost no adenosine receptor antagonistic properties, potentiates the inhibition of platelet aggregation by dipyridamole. An inhibitory effect similar to that of dipyridamole can be obtained combining a pure adenosine uptake inhibitor (RE 102 BS) with a pure phosphodiesterase inhibitor (MX-MB 82 or enprofylline). Mixing the blood during preincubation with dipyridamole increases the degree of inhibition. Lowering the haematocrit slightly reduces the effectiveness.Although we did not carry out direct measurements of adenosine levels, the results of our pharmacological studies clearly show that dipyridamole inhibits platelet aggregation in whole blood by blocking the reuptake of adenosine formed from precursors released by red blood cells following microtrauma. Its slight phosphodiesterase inhibitory action potentiates the effects of adenosine on platelets.

scholarly journals In Vitro Effects of Doxycycline on Replication of Feline Coronavirus

Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 312
Author(s):  
Magdalena Dunowska ◽  
Sayani Ghosh
Keyword(s):  
Inhibitory Concentration ◽  
Infectious Virus ◽  
Treatment Options ◽  
Inhibitory Effect ◽  
Virus Titration ◽  
Reverse Transcription Quantitative Pcr ◽  
In Vitro Effects ◽  
Dose Dependent ◽  
Feline Coronavirus

Feline infectious peritonitis (FIP) is a sporadic fatal disease of cats caused by a virulent variant of feline coronavirus (FCoV), referred to as FIP virus (FIPV). Treatment options are limited, and most of the affected cats die or are euthanized. Anecdotally, doxycycline has been used to treat FIP-affected cats, but there are currently no data to support or discourage such treatment. The aim of this study was to establish whether doxycycline inhibits replication of FIPV in vitro. The virus was cultured in Crandell-Rees feline kidney cells with various concentrations of doxycycline (0 to 50 µg/mL). The level of FIPV in cultures was determined by virus titration and FCoV-specific reverse-transcription quantitative PCR. Cell viability was also monitored. There was no difference in the level of infectious virus or viral RNA between doxycycline-treated and untreated cultures at 3, 12- and 18-hours post-infection. However, at 24 h, the growth of FIPV was inhibited by approximately two logs in cultures with >10 µg/mL doxycycline. This inhibition was dose-dependent, with inhibitory concentration 50% (IC50) 4.1 µg/mL and IC90 5.4 µg/mL. Our data suggest that doxycycline has some inhibitory effect on FIPV replication in vitro, which supports future clinical trials of its use for the treatment of FIP-affected cats.

Hepatoma Cell Cultures as In Vitro Models for the Hepatotoxicity of Xenobiotics

1988 ◽  
Vol 16 (1) ◽  
pp. 32-37
Author(s):  
Margherita Ferro ◽  
Anna Maria Bassi ◽  
Giorgio Nanni
Keyword(s):  
Cell Lines ◽  
Cell Cultures ◽  
Membrane Lipids ◽  
Hepatoma Cell ◽  
Positive Control ◽  
In Vitro Models ◽  
Low Concentrations ◽  
Formation Efficiency ◽  
Dose Dependent

Two hepatoma cell cultures were examined as in vitro models to be used in genotoxicity and cytotoxicity tests without the addition of bioactivating enzymes. The MH1C1, and HTC hepatoma lines were used in this study to establish their sensitivity to a number of xenobiotics, namely, cyclophosphamide (CP), the classical positive control in bioactivation tests; benzaldehyde (BA), a short-chain aldehyde; and 4-hydroxynonenal (HNE), a major toxic end-product of the peroxidative degradation of cell membrane lipids. As a first approach, we compared the following cytotoxicity tests: release of lactate dehydrogenase (LDH), and colony formation efficiency (CF). Colony-forming cells were exposed to the drugs according to different procedures, before or after the anchorage phase. The leakage of LDH into the medium following exposure of both cell lines to HNE, CP and BA for up to 24 hours was found not to be a good index of cytotoxicity. A better indicator of cytotoxicity was CF, as evaluated by exposure of the cells 24 hours after seeding. The effects were detectable at very low concentrations, corresponding to 10, 90 and 100μM for HNE, CP and BA, respectively. The impairment of CF efficiency was dose-dependent and time-dependent, and several differences between the two cell lines were observed.

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