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Query: UMLS:C0220723 (PCA)
 4,687 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Since 2-(diethylamino)-7-methoxychromone (III a) showed remarkable activity in the rat PCA test, some modifications to its structure were made. For instance new substituents such as chlorine or nitro group were introduced into the molecule and the diethylamino group modified. Thus, 2-(ethylamino)-7-methoxychromone (IX) was prepared by treating 3-methoxyphenol with N-ethylethoxycarbonylacetamide in the presence of phosphorus oxychloride. In this case a small amount of 4-chloro-7-methoxycoumarin was also isolated from the reaction mixture. Moreover compounds (XIV), (XV), (XVII) structurally related to sodium cromoglycate were prepared. The pharmacological screening of some compounds showed a useful antiallergic activity.
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PMID:[Chemistry and pharmacology of pyran derivatives. 16. Derivatives of 2-(dialkylamino)-7-methoxychromone with antiallergic activity]. 286 20

The N,N-disubstituted 4-amino-2H-pyrido[1,2-a]pyrimidin-2-ones (III) and isomer 2-amino-4H-pyrido[1,2-a]pyrimidin-4-ones (IV) were obtained from the reaction of 2-aminopyridine with the N,N-disubstituted ethyl malonamate/phosphorus oxychloride reagent (II), in refluxing 1,2-dichloroethane. 2-[(N-Benzyl, N-ethyl)amino]derivative (IV b) was also prepared in excellent yield by treating 2-chloro-4H-pyrido[1,2-a]pyrimidin-4-one (V) with N-ethylbenzylamine. Finally, hydrogenation (Raney Nickel) of 4-[(N-ethyl,N-phenyl)amino]-2H-pyrido[1,2-a]pyrimidin-2-one (III e) afforded 6,7,8,9-tetrahydroderivative (VI) which in turn was treated with potassium borohydride to give 1,6,7,8,9,9a-hexahydroderivative (VII). Several compounds described in the present paper, along with some other compounds (III) and (IV) previously synthesized by us (1,2), were tested for various pharmacological activities. The antiallergic activity (PCA in the rat), even though found in several compounds examined, turned out to be submaximal in any case, in spite of the high dose administered (500 mg/kg p.o. as a rule). The most active compound (the activity being estimated at 0.42 times that of thiaramide hydrochloride) was the 4-aminoderivative (III e). The 2-aminoderivatives (IV) series, was found to have marked antiinflammatory properties (carrageenin oedema in the rat); nevertheless, this activity was related to toxic symptoms with the exception of compound (IV b), almost asymptomatic at the administered dose (200 mg/kg p.o.). Moreover the 2-aminoderivatives (IV) generally showed weak adrenolitic activity in vitro (rat seminal vesicles), which was estimated to be from 100 to 1000 times less than that of phenoxybenzamine.
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PMID:[Derivatives of pyrimidine 1,2-condensate. IV. Synthesis and pharmacological properties of the N,N-disubstituted 4-amino-2H-pyrido(1,2-a)pyrimidin- 2-ones and 2-amino-4H-pyrido(1,2-a)pyrmidin-4-ones]. 322 96

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

Using phosphorus-31 nuclear magnetic resonance (P-31 NMR) spectroscopy the rat crystalline lens was evaluated as a potential animal model for the study of lens metabolic processes relevant to the human. The P-31 NMR spectra of intact rat lenses and rat lens PCA extracts provided comparable qualitative and quantitative results concerning the tissue levels of the phosphorus-containing metabolites of intermediate metabolism. The study also establishes the feasibility of examining intact rat lens metabolism by P-31 NMR. Comparisons with reported human and rabbit lens metabolite levels revealed significant differences; consequently, metabolic information derived from rat lens studies should be extrapolated to the human with caution.
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PMID:Analysis of intact rat lens metabolites by P-31 NMR spectroscopy. 731 90

The microfilariae and adults of Setaria cervi, a filarial parasite of Indian water-buffalo (Bubalus bubalis Linn.) and of other ruminants were analysed for various biochemical constituents. Both stages of the parasite were rich in protein, carbohydrate, and lipids while nucleic acids were detectable in only small amounts. Microfilariae and adults contained 10 and 25% dry matter, 57.4 and 63.0% protein, 8.9 and 14.8% carbohydrate, and 12.8 and 9.2% lipid, respectively. Reducing sugars accounted for 52 and 67% respectively of the total carbohydrate in these two stages. Glycogen accounted for 95% of total carbohydrate in the cold PCA soluble fraction of adult worms while its concentration in microfilariae was very low. Glucose was the main constituent of reducing sugars while concentrations of fructose were very low. Microfilariae contained more lipids, nucleic acids, mucopolysaccharides, and total phosphorus than adults. The phospholipid percentage was higher in microfilariae than in adults. The amino acid pattern of both stages was very similar.
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PMID:Biochemical composition of microfiliarial and adult stages of Setaria cervi. 739 8

Stimulation of 3T3 cells by forskolin (30 microM) led to an increase in cellular cAMP levels, as detected by 31P-NMR, in both PCA extracts and living cells incorporated in basement membrane gel (BMG) threads. At the same time cAMP was exported in large amounts to the extracellular space. The in vivo experiments showed a decrease of more than 50% in both the PCr and ATP levels within 90 min of stimulation with forskolin. Reperfusion with fresh medium without the drug resulted in the full recovery of the phosphorus energy metabolism. A significant increase in phosphocholine (PC) was observed in 1H and 31P spectra of the PCA extracts concomitant to the rise in cAMP level. 13C spectra of PCA extracts prepared after forskolin stimulation in the presence of [1-13C]glucose indicated a serious inhibition of glycolysis, which was followed by a disordering of the phosphorus energy metabolism. Our results show a significant imbalance in the metabolic homeostasis during stimulation of 3T3 cells with forskolin.
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PMID:Response of 3T3 cells on stimulation of adenylate cyclase by forskolin, studied by multinuclear NMR spectroscopy. 838 96

As part of our ongoing research on cardiac hypoxia tolerance we have conducted 31P nuclear magnetic resonance (NMR) studies of isolated, perfused, working hearts from freshwater turtles, animals that are well known for their ability to tolerate prolonged periods of anoxia. A striking feature of turtle heart spectra is an extremely high concentration of NMR visible phosphodiesters (PDEs). Cardiac spectra from mammals, on the other hand, typically exhibit only a small resonance in the PDE region. Our aim in this study was to compare myocardial PDE profiles between the highly hypoxia tolerant western painted turtle (Chrysemys picta bellii) and the relatively hypoxia sensitive softshelled turtle (Trionyx spinifer) in order to begin to rest the hypothesis that high constitutive levels of cytosolic PDEs may play a role in conferring hypoxia and ischemia tolerance on the myocardium. We also collected 31P-NMR spectra of PCA extracts of tissue from these species and from Kemp's ridley sea turtles (Lepidochelys kempi), as well as spectra from isolated hearts and PCA extracts of red-eared sliders (Trachemys [formerly Pseudemys] scripta]). Total NMR visible phosphodiesters make up 24 +/- 8.6% of the total NMR visible phosphorus in Chrysemys hearts, 20.7 +/- 5.9% in Trachemys hearts, but only 12.2 +/- 5.1% in Trionyx hearts (P < 0.05). We have identified three distinct PDEs in turtle hearts: glycerophosphorylcholine (GPC); glycerophosphorylethanolamine (GPE); and serine ethanolamine phosphodiester (SEP). SEP is the dominant compound in Chrysemys and Trachemys (79.3 +/- 10.2% and 84.7 +/- 3.7% of total PDE, respectively), while GPC is most abundant in Trionyx (74.0 +/- 4.3% of total PDE) and Lepidochelys (not quantitated). The function of this class of compounds is unclear but it has been suggested that cytosolic PDEs may function as lysophospholipase inhibitors, a role that would decrease the rate of membrane phospholipid turnover. Our comparative data suggest that cytosolic PDEs could play a role in phospholipid sparing during anoxic or ischemic stress in turtles but a direct test of this hypothesis awaits future experimentation.
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PMID:31P-NMR determinations of cytosolic phosphodiesters in turtle hearts. 950 28

Temporal variability in lake phytoplankton is controlled largely by a complex interplay between hydrodynamic and chemical factors, and food web interactions. We explored mechanisms underlying phytoplankton interannual variability in Lake Washington (USA), using a 25-yr time series of water quality data (1975-1999). Time-series analysis and PCA were used to decompose chlorophyll data into modes of variability. We found that phytoplankton dynamics in Lake Washington were characterized by four seasonal modes, each of which was associated with different ecological processes. The first mode coincided with the period when the system was light limited (January-March) and phytoplankton patterns were driven by the amount of available solar radiation. The second mode (April-June) coincided with the peak of the spring bloom and the subsequent decline of phytoplankton biomass, and was largely controlled by total phosphorus levels and grazing pressure from cladoceran zooplankton. Evidence of co-dependence and tight relationship between phytoplankton and cladoceran dynamics were also found from July to October when a large portion of the phosphorus supply in the mixed layer was provided by zooplankton excretion. The fourth mode (November-December) was associated with the transition to thermal and chemical homogeneity and the winter phytoplankton minima (2-2.5 microg/l). Finally, we examined the effects of meteorological forcing and large-scale oceanic climate fluctuations (ENSO and PDO) on phytoplankton dynamics and assessed the significance of their role on the interannual variability in the lake.
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PMID:Patterns and mechanisms of phytoplankton variability in Lake Washington (USA). 1538 Sep 91

Water extractable nitrate nitrogen, phosphate phosphorus and iron(II) in relation to the total amount of these essential elements were analyzed in fruits and seeds of medicinal plants. Water extraction was chosen to simulate in the analytical procedure the way plant samples are prepared and used by people. The total amounts of nitrogen, phosphorus and phosphate phosphorus were determined in the range of concentration of mg/g of dry plant weight, however, the total and extractable iron and nitrate nitrogen in mg/kg of dry weight. The nitrate nitrogen appeared to be crucial factor in the differentiation of plant samples and its level is characterized by very wide range of concentrations, from 10.15 mg/kg to 1377.03 mg/kg of dry plant weight; however, it didn't exceed the Acceptable Daily Intake (ADI). Statistically significant correlation between N and P, N and Fe, P-PO4 and P, P-PO4 and N was found, probably caused by their co-participation in metabolism of medicinal plant's fruits. Thanks to results of PCA, the fruits of medicinal plants can be differentiated by the concentration of nitrogen and phosphorus and their water extractable fractions. PCA grouped analyzed samples into three clusters with similar concentration of elements, which depended on the plant species, and in some cases also on the place of cultivation in distant regions of the country.
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PMID:Water extractable forms of nitrogen, phosphorus and iron in fruits and seeds of medicinal plants. 1853 66

Temporal variations and regional distributions of dissolved nutrients and their elemental ratios in the Iranian coastal waters of the Southern Caspian Sea were investigated. The data were collected in 1996-97 (Phase I, as a background data and undisturbed ecosystem) and in 2005 (Phase II, as a disturbed ecosystem) at sampling points (from 10 to 100 m depths). In addition to the two main sampling exercises, additional sample collections were carried out during the period of 1994 to 2004 as a long-term study. This study showed that the dissolved inorganic nitrogen/dissolved inorganic phosphorus (DIN/DIP) ratios in the southern Caspian Sea vary within a very narrow range (4.47 to 5.78) within the euphotic and aphotic layers and is by one order of magnitude lower than what have been reported for several other marine ecosystems. Phytoplankton growth seems to be nitrogen limited while the levels of P and Si always remain high. Factor Analysis/Principal Component Analysis (FA/PCA) of the correlation matrix showed that the nitrogen compounds are associated with the main factor accounting for 25.7-26.2% of the total variance for both the sampling periods. During Phase I, the Chrysophyta were the major group, whereas during Phase II the proportion of Chrysophyta in the total community progressively decreased, while the other groups increased.
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PMID:Variations in nutrient concentration and phytoplankton composition at the euphotic and aphotic layers in the Iranian coastal waters of the Southern Caspian Sea. 1881 25


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