Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0220723 (PCA)
 4,687 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A study was made of the effect of anit-histamine, antiserotonin and of different anti-anaphylactic drugs on PCA reactions induced in mice with IgG1 or IgE. Further, using the ability of mouse IgE to sensitize rat mast cells, a comparative study was also made of PCA reactions induced in mice and rats with mouse IgE. Antihistamines produced a partial inhibition of PCA reactions induced in mice with mouse IgG1 or IgE and in rats with mouse IgE whereas antiserotonin inhibited PCA reactions induced in rats with mouse IgE, but had no effect on PCA reactions induced in mice with mouse IgG1 or IgE. The simultaneous use of antihistamine and antiserotonin resulted in a total inhibition of PCA reactions induced in mice with IgG1 and in a marked but not total inhibition of PCA reaction due to IgE; PCA reactions induced in rats with mouse IgE were totally inhibited. Compounds known to change the intracellular level of cyclic AMP were found to have little or no effect on PCA reactions induced in mice with either IgG1 or IgE in spite of producing a complete marked inhibition of PCA reactions induced with mouse IgE in rats. Diethylcarbamazine or disodium cromoglycate were also very effective inhibitors of rat PCA reactions induced with mouse IgE although having no effect on PCA reaction induced in mice with this same antibody or with IgG1. Thus, in spite of sharing common mediators released from the same type of target cell sensitized with the same type of antibody, PCA reactions induced in mice and rats with mouse IgE reacted very differently to the pharmacological effect of most of the drugs tested. This fact seems to indicate that the physiological mechanism operating in mouse mast cells are different from those operating in rat mast cells.
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PMID:Homologous passive cutaneous anaphylaxis (PCA) in mice and heterologous PCA induced in rats with mouse IgE. 17 37

Potassium iodide (KI) has been shown to impair thyroid protein biosynthesis both in vivo and in vitro. The present study was performed in order to clarify its mechanism of action. Ribonucleic acid (RNA) synthesis was studied in beef thyroid slices with either [32P] or [3H]-uridine as labelled precursors. Both KI and thyroxine (T4) at 10(-5) M significantly decreased RNA labelling under our conditions. In other experiments RNA degradation was examined in pulse-labelled and actinomycin D-treated slices. KI did not modify the degradation of the [3H]-RNA thus indicating that it interferes with the biosynthesis rather than with the degradation of RNA. Taking the perchloric acid soluble radioactivity as a rough index of the precursor pool the present results would indicate an action at this level. Both KC1O4 and methylmercapto-imidazole relieved the gland from the inhibitory action of KI, supporting the view that an intracellular and organified form of iodine is responsible for this action. Since T4 also reproduced the effects of KI on RNA synthesis we would like to propose iodothyronines as the intermediates of this action. Cyclic AMP has been shown to stimulate thyroid protein biosynthesis. The present results demonstrate an action at the RNA level. Cyclic AMP increased both the PCA-soluble and RNA-linked radioactivity, thus suggesting an effect at the RNA precursor pool. KI at 10(-5) M blocked the action of 2 mM cyclic AMP.
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PMID:Action of KI, thyroxine and cyclic AMP on [3H]uridine incorporation into the RNA of thyroid slices. 18 34

Thyrotrophin (TSH) regulates the biosynthesis of thyroid protein and RNA. This action is mediated by adenylate cyclase and cycl AMP. In the present study the action of cyclic GMP and cyclic CMP was investigated in beef slices. Both cyclic AMP and cyclic GMP significantly increased the incorporation of [3H]uridine into RNA. These effects were blocked by actinomycin D, suggesting that their action is located at a preor at a transcriptional step. The PCA soluble fraction radioactivity followed in parallel with tha variations observed in the RNA fraction, supporting the view that cyclic nucleotides may regulate RNA by modulating the nucleotide precursors pool. Cyclic CMP in concentrations between 0.35 to 1.5 mM progressively decreased the RNA labelling, and the values of the PCA soluble radioactivity again followed those of RNA. Furthermore, cyclic CMP also blocked the in vitro stimulatory action of cyclic AMP on the incorporation of [3H]leucine into protein, and of [3H]uridine into RNA. The present results provide the first information on the action of cyclic AMP on RNA synthesis and suggest that negative signals may also play a part in the regulation of thyroid function.
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PMID:Action of cyclic nucleotides on protein and RNA synthesis in the thyroid. 18 48

Immediately after stimulation with glucose in vitro, isolated rat pancreatic islets prelabeled with [32P]orthophosphate release a pulse of [32P]orthophosphate into the media (the "phosphate flush"). Islets have been rapidly frozen before, during, and after this pulse to assess the concurrent changes in the distribution of tissue radioactivity. Under the present experimental conditions, approximately 90% of the islet radioactivity was soluble in perchloric acid (PCA-soluble) immediately before stimulation and slightly more than half of that was present as [32P]orthophosphate. The tissue pool of [32P]orthophosphate declined 55% and 62% after 7 and 14 min of stimulation which, respectively, incorporated the peak and the end of the heightened efflux of radioactivity. The net decrementa in tissue orthophosphate could account for all of the radioactivity which was released during the "phosphate flush." During the 14-min period of stimulation, labeled ATP and GTP (which had accounted for 13% and 4% of total PCA-soluble radioactivity before stimulation) increased 51% and 35%, respectively, and labeled ADP and AMP (which had accounted for 5.4% and 1.5% of PCA-soluble counts) fell 36% and 77%, respectively. Certain other PCA-soluble components, such as phosphorylcholine and phosphorylethanolamine, and total PCA-insoluble radioactivity were not demonstrably altered. The findings indicate that the "phosphate flush" originates from a labile pool of tissue orthophosphate. It remains to be established whether the simultaneous changes in the turnover of selected nucleotides are coupled to the translocation of orthophosphate or are mediated separately.
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PMID:32P-labeling patterns in rat pancreatic islets: tissue source of the radiophosphate released after glucose stimulation. 36 45

A method for a simultaneous separation of malondialdehyde (MDA), ascorbic acid and adenine nucleotide derivatives in biological samples by ion-pairing high-performance liquid chromatography is presented. The separation is obtained by an LC-18-T 15 cm x 4.6 mm 3 microns particle size column using tetrabutylammonium as the pairing ion. The starting buffer consists of 10 mM tetrabutylammonium hydroxide, 10 mM KH2PO4 plus 1% methanol, pH 7.00. A step gradient is formed using a second buffer consisting of 2.8 mM tetrabutylammonium hydroxide, 100 mM KH2PO4 plus 30% methanol, pH 5.5. Under these chromatographic conditions a highly resolved separation of MDA, ATP, ADP, AMP, adenosine, ascorbic acid, GTP, GDP, IMP, inosine, Hypoxanthine, Xanthine, uric acid, NAD, and NADP can be performed in about 36 min. In addition, the separation of NADH and NADPH can also be obtained; this renders the present method suitable for the detection of these reduced coenzymes in alkaline extracts from tissue samples. Data referring to PCA extracts from ischemic and reperfused isolated rat hearts and from human erythrocytes peroxidized in vitro by a challenge with 1 mM NaN3 and various concentrations of H2O2 are reported. The relevance of this chromatographic method lies in the possibility to determine directly MDA concentrations avoiding the unspecific thiobarbituric acid colorimetric test, any other manipulation of the sample out of the PCA extraction, and any possible coelution of other acid soluble compounds. The simultaneous determination of MDA, ascorbic acid, and of ATP and its degradation products gives the opportunity to correlate, by a single chromatographic run, peroxidative damages with the energy state of the cell which is of great importance in studies of ischemic and reperfused tissues.
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PMID:Simultaneous separation of malondialdehyde, ascorbic acid, and adenine nucleotide derivatives from biological samples by ion-pairing high-performance liquid chromatography. 195 65

IgG1, antibody-mediated homologous passive cutaneous anaphylaxis at 1.5 h (1.5-hour PCA) was elicited in the ears of mice and the effects of different drugs were studied. The reaction, as measured by the amount of extravasated dye, was inhibited by antihistamines, antiserotonins, cyclic AMP-elevating agents, tranilast and ketotifen, but not by an SRS-A antagonist (FLP 55712), lipoxygenase inhibitors, cyclooxygenase inhibitors and disodium cromoglycate. These results suggest that the pharmacological profile of 1.5-hour PCA resembles that of 48-hour PCA mediated by IgE antibody in the mouse ear.
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PMID:Effects of different drugs on passive cutaneous anaphylaxis elicited in the mouse ear at 1.5 hours. 245 88

1. Lyophilized crude rRNA from trout (Salmo gairdneri R.) liver was composed (w/w) of 2.9% protein, traces of DNA and glycogen, 13% water and 83% pure rRNA. The RNA content was derived from the discrepancy between effectively found (8.1%, w/w) and theoretical phosphorus content (9.6%, w/w). 2. The theoretical phosphorus content was calculated on the basis of the molar distribution of nucleotides in rRNA (UMP:GMP:AMP:CMP = 24.7%:30%:19.5%:25.8%), established upon cation exchange chromatography of alkali-degraded crude rRNA. 3. The extinction coefficient (corrected for moisture and none-ribonucleic acid contaminants) of pure rRNA in 0.2 N PCA after digestion in 0.3 N KOH at 37 degrees C for 90 min is 361 in terms of E1%260. That of undegraded, pure rRNA in water amounts to 279.
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PMID:Specific UV-absorbancy of pure rRNA isolated from trout liver as a standard for the quantification of ribonucleic acid from fish tissues. 366 18

A bioassay, using high-performance liquid chromatography (HPLC) analysis of platelet adenosine nucleotides and hypoxanthine, was studied for its potential use as a test for MH susceptibility. A protocol for the assay was developed, based on the method outlined by Solomons and Masson. The HPLC procedure was a rapid, efficient, sensitive, and highly reproducible technique for measuring ATP, ADP, AMP, and hypoxanthine in platelets. Conditions of extraction and storage were critical for preventing degradation of the nucleotides. Extraction of nucleotides at icebath temperature was found necessary. Storage of platelet extract in PCA, even at -20 degrees C, showed loss of ATP and ADP; hence, neutralization with KOH was essential before storage. Contrary to the findings of Solomons et al., the present study demonstrated that neither ATP depletion nor per cent reduction in nucleotide ratios in platelets treated with halothane can be used as a definitive test for the diagnosis of MH susceptibility. The reason for this disagreement is unclear; however, differences in methods and altitude are implicated. It is possible that the platelet is not affected by malignant hyperthermia and thus cannot serve as a test system for the detection of the syndrome.
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PMID:The use of a platelet nucleotide assay as a possible diagnostic test for malignant hyperthermia. 402 92

A study was made of the PCA reaction in rat hind paw for analysis of the mechanisms of the of the anaphylactic release of mediators in vivo. Also studied was the function of cyclic AMP in the anaphylactic release of histamine during PCA induced in rats with homologous and heterologous antibody. A close correlation was seen among edema formation, histamine release and decrease of cyclic AMP during homologous and heterologous PCA. Theophylline, epinephrine and isoproterenol increased the cyclic AMP level and strongly inhibited edema formation and histamine release, in all animals. Aminopyrine and trasylol also increased the cyclic AMP level but aminopyrine did not inhibit either edema formation or histamine release in case of heat labile homocytotropic antibody induced PCA in rats and trasylol did not inhibit histamine release in any animal. Methysergide and mepyramine strongly inhibited histamine release but did not alter cyclic AMP levels. Thus, the increase of the cyclic AMP level did not always inhibit the histamine release during PCA in rats. It has also been demonstrated that the PCA reaction in rat hind paw is a suitable model for studying the mechanisms of the anaphylactic release of mediators in vivo.
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PMID:[Pharmacological studies on rat passive cutaneous anaphylaxis (PCA) (author's transl)]. 616 49

ATP, ADP, AMP and glycerate 2, 3-bisphosphate in blood are frequently analyzed in order to evaluate erythrocytes for blood donation and to diagnose hemolytic anemias. In order to find an uncomplicated and safe procedure for the preanalytical treatment of blood a freezing-storing procedure using dry ice was worked out and combined with a later PCA precipitation. The pre-freezing stability of the components was also investigated and found to be best at room temperature.
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PMID:Specimen handling for the assay of adenylates and glycerate 2, 3-bisphosphate in erythrocytes. 731 20


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