Search results for "terase"
showing 10 items of 446 documents
Atherogenic properties of enzymatically degraded LDL: selective induction of MCP-1 and cytotoxic effects on human macrophages.
1998
Abstract —The mechanisms underlying the selective accumulation of macrophages in early atherosclerotic lesions are poorly understood but are likely to be related to specific properties of altered low density lipoprotein (LDL) deposited in the subendothelium. Enzymatic, nonoxidative degradation of LDL converts the lipoprotein to a potentially atherogenic moiety, enzymatically altered LDL (E-LDL), which activates complement and is rapidly taken up by human macrophages via a scavenger receptor–dependent pathway. Immunohistological evidence indicates that E-LDL is present in an extracellular location in the early lesion. We report that E-LDL causes massive release of monocyte chemotactic prote…
On the geographical distribution of pseudocholinesterase variants.
1975
The incidence of pseudocholinesterase (PCHE equals E.C. 3.1.1.8) variants in samples of 8 different population (total of 2218 individuals) is reported. Together with previously mentioned data from the literature, a general survey on the geographical distribution of PCHE isoenzymes is given. Possible reasons for present-day heterogeneity of their distribution are also discussed. Concerning the incidence of the C5 variant, it is pointed out that the validity of applying population genetic models depends upon the accuracy of the genetic basis.
Inhibition by oxotremorine of acetylcholine resting release from guinea pig-ileum longitudinal muscle strips
1975
1. Longitudinal muscle strips of the guinea-pig ileum were incubated in Tyrode solution containing either DFP or physostigmine as cholinesterase inhibior. After a 90 min preincubation period the acetylcholine resting release into the medium was determined. Acetylcholine was estimated by gas chromatography. 2. The resting release was 0.39 nmol/g×min irrespective of the cholinesterase inhibitor used. In the presence of hexamethonium, or after omission of external calcium, the resting release fell by 50 and 55%, respectively. 3. Oxotremorine (10−5 and 10−4 M) significantly inhibited the resting release of acetylcholine by 25 and 33%, respectively. The inhibitory effect of oxotremorine was comp…
Antimuscarinic action of quinidine on the heart? A study in myocardial preparations from cat hearts
1984
Quinidine exerts anticholinergic effects which have been ascribed to atropine-like properties of the drug. We have examined the effects of acetylcholine on the force of contraction in isolated heart muscle preparations from cats and compared the inhibitory effects of atropine with those of quinidine. The effects of acetylcholine were antagonized competitively in the presence of atropine. The Schild-plot yielded a straight line; the slope was not significantly different from unity. In the presence of quinidine, the concentration-response curve of acetylcholine was shifted to the right as with atropine, however, the Schild-plot yielded a regression line which was not linear; the slope was sta…
Cholinesterase activity and exposure time to acetylcholine as factors influencing the muscarinic inhibition of [3H]-noradrenaline overflow from guine…
1985
Guinea-pig isolated atria were incubated and loaded with [3H]-noradrenaline. The release of 3H and of [3H]-noradrenaline was induced by field stimulation (6-9 trains of 150 pulses at 5 Hz). The stimulation-evoked overflows of 3H and of [3H]-noradrenaline were determined. In the absence of an inhibitor of acetylcholinesterase, acetylcholine (12 min preincubation before nerve stimulation, up to 10 microM) failed to inhibit the evoked [3H]-noradrenaline overflow. In the presence of atropine, an increase by acetylcholine of evoked release was observed in the same atria. In contrast, the selective muscarinic agonist methacholine significantly decreased the evoked overflow. The inhibition was ant…
Acetylcholine via Muscarinic Receptors Inhibits Histamine Release from Human Isolated Bronchi
1997
Human bronchi were incubated in organ baths to measure histamine release. The calcium ionophore A23187 (10 mumol/L; 1 min) stimulated histamine release by 148 +/- 28% (n = 11) above the prestimulation level but was ineffective in epithelium-denuded bronchi. Neither bradykinin (0.1 mumol/L) nor compound 48/80 (10 micrograms/ml) triggered the release of histamine from epithelium-intact bronchi. Acetylcholine did not affect spontaneous histamine release (about 2 nmol/g x 5 min) but inhibited A23187-evoked histamine release in an atropine-sensitive manner. Already a concentration as low as 0.1 nmol/L acetylcholine was effective, the maximal inhibition (by 89%) occurred at 100 nmol/L, whereas a …
Use of atropine-treated Daphnia magna survival for detection of environmental contamination by acetylcholinesterase inhibitors.
2003
The toxicity of cholinesterase-inhibiting compounds (e.g., carbamates and organophosphates) is due to a decrease in acetylcholine metabolism, which results in a continuous stimulation of cholinergic receptors (muscarinic and nicotinic) that can be fatal. The goal of this study was to evaluate the protective effect of atropine (muscarinic receptor antagonist) against paraoxon-induced toxicity to Daphnia magna using its survival rate for the detection of environmental contamination by cholinesterase-inhibiting compounds. As expected, paraoxon was lethal to D. magna in a concentration-dependent manner. Noteworthy, the pretreatment of these organisms with atropine dramatically increased their s…
Glucose and Ethanol Tolerant Enzymes Produced by Pichia (Wickerhamomyces) Isolates from Enological Ecosystems
2012
A total of 17 Pichia ( Wickerhamomyces ) isolates obtained from enological ecosystems in the Utiel-Requena Spanish region were characterized by physiological (using API 20C AUX strips and ID Yeast Plus System miniaturized identification systems) and molecular (PCR-RFLP and sequencing) techniques as belonging to the species P. fermentans, P. membranifaciens , and W. anomalus . Data support the reclassification of P. anomala as Wickerhamomyces anomalus . In order to characterize their enzymatic abilities, xylanase, β-glucosidase, lipase, esterase, protease, and pectinase qualitative and quantitative assays were made. Wickerhamomyces anomalus and P. membranifaciens were the most interesting sp…
Differential roles of cAMP and cGMP in megakaryocyte maturation and platelet biogenesis
2012
The cyclic nucleotides cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) regulate the activity of protein kinase A (PKA) and protein kinase G (PKG), respectively. This process helps maintain circulating platelets in a resting state. Here we studied the role of cAMP and cGMP in the regulation of megakaryocyte (MK) differentiation and platelet formation. Cultured, platelet-producing MKs were differentiated from fetal livers harvested from 13.5 days postcoital mouse embryos. MK development was accompanied by a dramatic increase in cAMP production and expression of soluble guanylate cyclase, PKG, and PKA as well as their downstream targets vasodilator-stimulated ph…
PHOSPHODIESTERASE INHIBITORS PIROXIMONE AND ENOXIMONE INHIBIT PLATELET AGGREGATION IN VIVO AND IN VITRO
1997
The phosphodiesterase type III inhibitors piroximone (PIR) and enoximone (ENO) exert positive inotropic and vasodilating effects in patients with severe heart failure. PIR and ENO raise cyclic AMP levels in cardiac and vascular smooth muscle cells. Platelet activity is also regulated by intracellular levels of cyclic AMP. In this study we have investigated the effects of PIR and ENO on platelet activity in vivo and in vitro. PIR and ENO inhibited ADP induced platelet aggregation in a time- and concentration-dependent manner with IC50-values of 67 +/- 14 mumol/l and 129 +/- 6 mumol/l, respectively. Coincubation of PIR with the adenylate cyclase activator iloprost resulted in a synergistic po…