Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: KEGG:D01453 (caffeine)
21,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Dictyostelium discoideum strain M28, which has been used widely in genetic studies, was found to carry a radiation-sensitive mutation. This allele, termed rad-100, was recessive in heterozygous diploids and mapped in linkage group III. Complementation analysis and survival studies on strains carrying rad-100 suggested that this allele defines a new radiation-sensitive locus in D. discoideum, and this locus has been designated radE. radE strains were moderately sensitive to ultraviolet light (D10 90 J m-2) and slightly sensitive to 137Cs gamma rays D10 255 krad). radE strains also exhibited increased sensitivity to killing by N-methyl-N'-nitro-N-nitrosoguanidine but not by other alkylating agents such as ethyl methanesulphonate or methyl methanesulphonate. The frequency of spontaneous methanol-resistant (acrA) mutants was approximately the same in cultures of radE and radE+ strains. However, when amoebae of these strains were irradiated with ultraviolet light, the frequency of induced mutants was significantly lower in cultures of the radE strain. Furthermore, when amoebae of wild-type strain NC4 were plated in the presence of caffeine after ultraviolet-irradiation, the survival curves were very similar to the curves obtained for amoebae of radE strains in the presence or in the absence of caffeine. These results suggest that the radE100 mutation and caffeine interfere with an error-prone DNA repair pathway in D. discoideum.
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PMID:radE, a new radiation-sensitive locus in Dictyostelium discoideum. 54 58

A method was developed for determining theobromine and caeffine in cocoa and chocolate products by high pressure liquid chromatography. After a simple hot water extraction, both theobromine and caffeine were separated by using a reverse phase C18 column and a mobile phase of methanol-water-acetic acid (20 + 79 + 1). Theobromine and caffeine were quantitated at 280 nm; average recoveries were 98.7 and 95.0%; and coefficients of variation were 2.31 and 3.91%, respectively.
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PMID:High pressure liquid chromatographic determination of theobromine and caffeine in cocoa and chocolate products. 73 Jun 47

We attempted to isolate a carcinogenic substance from bracken fern (Pteridium aquilinum), a naturally occurring toxicant responsible for the production of chronic enzootic hematuria and urinary bladder cancer of cattle and carcinogenic for various target organs of several species. Hot methanol extracts of bracken fern were solubilized in water and extracted with chloroform followed by a mixture of n-butanol-butanone (1:1). That fraction was dried and triturated with ether-methanol (4:1), n-butanol, and finally absolute ethanol. The insoluble residue was dissolved in 10% aqueous methanol and passed through Dowex 1 OH-, Dowex 50 H+, or Dowex 1 OH- and then Dowex 50 H+ ion exchange resins. A condensed tannin, isolated from one ot the fractions, was identical to that isolated from bracken fern by the caffeine procedure used for the separation of tannins from other plant constituents. Three systems were used for bioassay; induction of bladder carcinoma by implantation of cholesterol pellets containing bracken fern fractions into the bladder lumens of mice; acute toxicity by ip injection of brachen fern fraction into mice; and growth inhibition of Escherichia coli. The following fractions induced significantly greater incidences of bladder carcinoma than did cholesterol pellets only: tannin, Dowex 50 H+, residue, n-butanol, and methanol. Tiliroside, a component of bracken fern fractions into the bladder lumens of mice; acute genic acid, and quercetin were not carcinogenic. Tannin was the most toxic (mean lethal dose: 0.16 mg/g) and carcinogenic. None of the carcinogenic fractions inhibited growth of E. coli.
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PMID:Identification of carcinogenic tannin isolated from Bracken fern (Pteridium aquilinum). 76

A fast and sensitive method by high performance liquid chromatography for the quantification of the methylxanthine metabolites of caffeine in human plasma is described. Plasma is extracted with 20% isopropanol in chloroform and the evaporated residue is redissolved and chromatographed on silica gel using dichloromethane containing 2.2% of a solution of methanol-ammonium formateformic acid (100:0.02:0.017). The method is suitable for metabolic and pharmacokinetic studies of all mono- and dimethylxanthines in plasma. The limits of quantification, with C.V. of 10% or less are 40 ng/ml for the dimethylxanthines, 100 ng/ml for 3- and 7-methylxanthine and 500 ng/ml for 1-methylxanthine.
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PMID:Simultaneous assay of the methylxanthine metabolites of caffeine in plasma by high performance liquid chromatography. 87 16

A rapid procedure has been devised for analyzing anti-epileptic drugs in serum by chemical ionization mass spectrometry. An internal standard, 5-(p-methylphenyl)-5-phenylhydantoin (MPPH), is added to serum diluted in buffer at pH 12. The mixture is washed with diethyl ether to remove neutral lipids, acidified, extracted with chloroform and the chloroform extract evaporated to dryness. The residue is then dissolved in methanol and an aliquot, corresponding to approximately 2% of the original mixture, is deposited in the glass capillary sample cup of the solid probe inlet of the mass spectrometer. The sample is then volatilized by heat into the ion source of the mass spectrometer, where it reacts with ionized methane reagent gas. As the temperature of the probe is increased, quasimolecular ion peaks of the protonated anticonvulsants appear, rise and fall on the oscilloscope tracing, indicating similar but not identical rates of volatilization. We recorded these peaks photographically by opening the shutter of the oscilloscope camera for the entire heating cycle. The concentrations of the anticonvulsants were estimated from the ratio of the height of the peaks of the drug to that of the internal standard on the photograph. The peak-height ratios were proportional to concentration within, above and below the therapeutic range. Other drugs, including barbiturates, carbamazepine, nicotine and caffeine, were readily identified when present. With one solid probe inlet, an assay could be performed every 2 min.
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PMID:Chemical ionization mass spectrometry for rapid assay of drugs in serum. 97 99

Pseudomonas putida, strain 40, originally isolated by enrichment on caffeine as the sole source of carbon and nitrogen, has been developed to grow on 0.5% caffeine. The organism will grow on any N-methyl derivative of xanthine containing one or more methyl groups at the 1, 3, or 7 positions. An investigation of the activities of resting cell suspensions and cell-free preparations together with the detection of metabolic intermediates suggest that caffeine is first metabolized by the action of an enzyme which is capable of hydrolytically removing all three methyl groups with the production of methanol and free xanthine. The methanol presumably is oxidized to the final product, CO2, through the sequential action of methanol, formaldehyde, and formate dehydrogenases, which are induced by growth on caffeine. Furthermore, the xanthine would seem to be channeled through conventional pathways of purine degradation through the action of xanthine dehydrogenase and uricase, both induced by growth on caffeine. However, a variety of data suggests that the metabolism of caffeine may be compartmentalized in the cell and metabolized separately from externally added xanthine. Additional studies indicated that the cell is permeable to the methylxanthines. The significance of these findings is discussed.
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PMID:Metabolism of N-methylpurines by a Pseudomonas putida strain isolated by enrichment on caffeine as the sole source of carbon and nitrogen. 115 47

Direct, quantitative, thin-layer chromatographic methods for the determination of ergotamine tartrate and caffeine in the presence of each other in blood and in pharmaceutical preparations are described. The blood is centrifuged, the plasma decanted from the coagulum and deproteinized with acetone-methanol. After removal of the solvent mixture, the active ingredients are extracted from the remaining aqueous solution with chloroform. In the case of the pharmaceutical preparations, the active ingredients are also extracted with chloroform or methanol. Ergotamine tartrate and caffeine are separated on pre-coated silica gel 60 F254 plates and measured directly on the thin-layer plate, ergotamine tartrate being determined by the fluorescence method, excitation wavelength 365 nm, at lambdamax.=450 nm and caffeine by the reflactance method at lambdamax.=274 nm. The analytical methods are suitable for the bioavailability studies of these drugs in blood as they enable the determination of 20 ng ergotamine tartrate with a coefficient of variation of 6.7% and the determination of 200 ng caffeine with a coefficient of variation of 6.1%. The methods have also proved useful in the determination of the active ingredients of drug forms such as tablets and suppositories and can be well reproduced with a maximum coefficient of variation of 4.9% for ergotamine tartrate and 3.5% for caffeine.
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PMID:Quantitative thin-layer chromatographic analysis of ergotamine tartrate and caffeine in the nanogram range. 125 62

A solid-phase extraction and reversed phase high performance liquid chromatographic method (RP-HPLC) was developed for the rapid determination of 13 diuretics (belonging to five different pharmacological groups), probenecid, caffeine and pemoline in urine. Two ml urine sample was first adsorbed on a XAD-2 column, then eluted with ether-ethyl acetate (1:1). The eluate was evaporated to dryness and reconstituted in methanol. The methanolic solution was injected into a HP LiChrosorb RP-18 column, using phosphate buffer (pH 3) and acetonitrile as the mobile phase and monitored at 216 nm, 230 nm, and 275 nm on a diode array ultraviolet detector. The extraction recoveries of 16 drugs were above 75%. The limits of detection ranged from 0.3-3.0 micrograms/ml of urine. All drugs were separately administered to healthy volunteers, positive urine samples were collected, and urinary excretion-time curves of some drugs were reported.
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PMID:[Solid-phase extraction and RP-HPLC screening procedure for diuretics, probenecid, caffeine and pemoline in urine]. 130 35

A high-performance liquid chromatographic method with ultraviolet photometric detection has been developed for the quantitation of cotinine and trans-3'-hydroxycotinine in human serum. A solid-phase extraction procedure was performed for the analytes and the internal standard, N-ethylnorcotinine, before chromatography. The use of a 30-cm reversed-phase column and a mobile phase of water-methanol-0.1 M sodium acetate-acetonitrile (67:24.5:6.5:2, v/v), pH 4.3, prevented the co-elution of caffeine with cotinine. The limit of quantitation observed with this method was 5 ng/ml for both cotinine and trans-3'-hydroxycotinine. The present method proved useful for the determination of serum levels of these metabolites, correlating with nicotine daily intake.
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PMID:Simultaneous determination of cotinine and trans-3'-hydroxycotinine in human serum by high-performance liquid chromatography. 140 Jul 67

The universal nature of the stimulant or euphoric effect of addictive drugs suggests that it may be an important predictor of a drug's addiction potential. Furthermore, assessment of stimulant sensitivity could be useful for predicting the liability of individuals to drug abuse. The stimulant actions of abused drugs from different pharmacological classes may share a common biological mechanism. We investigated this notion by assessing the drug responses relative to base-line locomotor activity of mice selectively bred for increased (FAST) and reduced (SLOW) sensitivity to ethanol-induced stimulation. FAST mice were more sensitive than SLOW mice to the stimulant effects of methanol (1.5-3.0 g/kg), t-butanol (0.2-0.6 g/kg), n-propanol (0.15-1.2 g/kg), pentobarbital (10-40 mg/kg) and phenobarbital (15-120 mg/kg). FAST and SLOW mice were similarly stimulated by d-amphetamine (1.25-10 mg/kg) and caffeine (2.5-20 mg/kg). The activity of FAST and SLOW mice was equally depressed by nicotine (0.5-2.0 mg/kg) and morphine (4-75 mg/kg). Finally, FAST mice were unaffected, whereas SLOW mice were depressed by diazepam (1-8 mg/kg). Selection for relative sensitivity to stimulation by ethanol has generalized to other alcohols and to barbiturates, but not to several other abused drugs, including amphetamine. The data presented here support a hypothesized common mechanism of stimulant action for alcohols and barbiturates, and suggest that differences in sensitivity to drug stimulant effects can be seen in the absence of dopamine system differences.
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PMID:Acute sensitivity of FAST and SLOW mice to the effects of abused drugs on locomotor activity. 157 69


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