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| Registros recuperados: 43 | |
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| Human skinned muscle fibers were used to investigate the effects of bovine serum albumin (BSA) on the tension/pCa relationship and on the functional properties of the Ca2+-release channel of the sarcoplasmic reticulum (SR). In both fast- and slow-type fibers, identified by their tension response to pSr 5.0, BSA (0.7-15 µM) had no effect on the Ca2+ affinity of the contractile proteins and elicited no tension per se in Ca2+-loaded fibers. In contrast, BSA (>1.0 µM) potentiated the caffeine-induced tension in Ca2+-loaded fibers, this effect being more intense in slow-type fibers. Thus, BSA reduced the threshold caffeine concentration required for eliciting detectable tension, and increased the amplitude, the rate of rise and the area under the curve... |
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Palavras-chave: Calcium-release channel; Sarcoplasmic reticulum; Human muscle fiber; Bovine serum albumin; Caffeine. |
| Ano: 1997 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997000500017 |
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| Denadai,B.S.; Denadai,M.L.D.R.. |
| Controversy still exists concerning the potential ergogenic benefit of caffeine (CAF) for exercise performance. The purpose of this study was to compare the effects of CAF ingestion on endurance performance during exercise on a bicycle ergometer at two different intensities, i.e., approximately 10% below and 10% above the anaerobic threshold (AT). Eight untrained males, non-regular consumers of CAF, participated in this study. AT, defined as the intensity (watts) corresponding to a lactate concentration of 4 mM, was determined during an incremental exercise test from rest to exhaustion on an electrically braked cycle ergometer. On the basis of these measurements, the subjects were asked to cycle until exhaustion at two different intensities, i.e.,... |
| Tipo: Info:eu-repo/semantics/other |
Palavras-chave: Caffeine; Anaerobic threshold; Endurance; Lactate; Perceived exertion. |
| Ano: 1998 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000400017 |
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| Sartor,Rosana Mary; Mazzafera,Paulo. |
| The low caffeine content in leaves of C. dewevrei (~ 0.5 mg/g) is due to a low biosynthesis associated with a fast degradation. On the other hand, high biosynthesis and low degradation confer a higher content (~ 8 mg/g) in leaves of C. arabica. In this work it was observed that cell cultures of C. dewevrei recovered the ability to synthesize caffeine almost in similar levels of C. arabica cultures. Tracer experiments with labelled carbon dioxide showed a significant accumulation of radioactivity in caffeine and metabolites, indicating an active biosynthesis. When the cultures were fed with labelled caffeine most of the radioactivity was recovered in caffeine, indicating that although active, degradation was not so efficient as in leaves, and therefore,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Coffee; Caffeine; Cell suspension culture; Methylxanthines. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132000000100009 |
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| Bührer,Nilton E.. |
| In this work the author puts in evidence a practical and at the same time rapid method for the determination of the cafein quantity in erva-mate, that may be utilized to perfection in food and industrial analyses or others that not demand scientific rigour. The author presents a description of the method and makes a comparison with the classical method of Grandval-Lajoux, showing that the differences between the one and the other are practically nil. In conclusion, the result of the three analyses of the same sample of erva-mate, made by the Grandval-Lajoux method are cited, show that the same differences appear as those shown between the rapid method suggested by the author and the classical method. In this case, the maximum difference was 0,06% and the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Caffeine; Erva-mate; Caffeine assay. |
| Ano: 2001 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132001000500007 |
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| Angelucci,M.E.M.; Cesário,C.; Hiroi,R.H.; Rosalen,P.L.; Cunha,C. Da. |
| We studied some of the characteristics of the improving effect of the non-specific adenosine receptor antagonist, caffeine, using an animal model of learning and memory. Groups of 12 adult male Wistar rats receiving caffeine (0.3-30 mg/kg, ip, in 0.1 ml/100 g body weight) administered 30 min before training, immediately after training, or 30 min before the test session were tested in the spatial version of the Morris water maze task. Post-training administration of caffeine improved memory retention at the doses of 0.3-10 mg/kg (the rats swam up to 600 cm less to find the platform in the test session, P<=0.05) but not at the dose of 30 mg/kg. Pre-test caffeine administration also caused a small increase in memory retrieval (the escape path of the rats... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Memory; Learning; Caffeine; Methylxanthines; Adenosine receptor antagonist; Morris water maze. |
| Ano: 2002 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2002001000013 |
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| Laranja,Alessandra Theodoro; Manzatto,Antonio José; Campos Bicudo,Hermione Elly Melara de. |
| Caffeine and used coffee grounds completely blocked the development of Aedes aegypti in the early stages, in treatments with the concentrations 1.0 mg/mL and 50 mg/mL, respectively. More advanced stages and even adults were obtained in lower concentrations of both substances, enabling observations to be made of mortality rate, longevity and esterase patterns. The experiments involved treatments using either eggs or 3rd instar larvae (L3), with or without the addition of fish food. Mortality rates prior to the adult stage and adult longevity were significantly different in the comparisons among treatments, in every kind of experiment, but in those using L3 larvae, their percentages were smaller. Observations of the time of larva and adult onset suggested... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aedes aegypti; Caffeine; Used coffee grounds; Mortality; Longevity; Esterases; Alternative control. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572003000400004 |
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| Bassani,R.A.; Bassani,J.W.M.. |
| Relaxation in the mammalian ventricle is initiated by Ca2+ removal from the cytosol, which is performed by three main transport systems: sarcoplasmic reticulum Ca2+-ATPase (SR-A), Na+-Ca2+ exchanger (NCX) and the so-called slow mechanisms (sarcolemmal Ca2+-ATPase and mitochondrial Ca2+ uptake). To estimate the relative contribution of each system to twitch relaxation, SR Ca2+ accumulation must be selectively inhibited, usually by the application of high caffeine concentrations. However, caffeine has been reported to often cause changes in membrane potential due to NCX-generated inward current, which compromises the reliability of its use. In the present study, we estimated integrated Ca2+ fluxes carried by SR-A, NCX and slow mechanisms during twitch... |
| Tipo: Info:eu-repo/semantics/other |
Palavras-chave: Myocardium; Relaxation; Calcium fluxes; Sodium-calcium exchanger; Sarcoplasmic reticulum calcium ATPase; Caffeine. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003001200014 |
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| Tagliari,Cristiane Vanessa; Sanson,Raquel K.; Zanette,André; Franco,Telma Teixeira; Soccol,Carlos Ricardo. |
| Various microorganisms including bacteria, yeast and fungi can degrade caffeine. There are few publications about caffeine degradation pathway in filamentous fungi, mainly by solid-state fermentation (SSF). Studies were carried out on degradation of caffeine and their metabolites by filamentous fungi in SSF using coffee husk as substrate. The purpose of this work was to investigate the caffeine degradation pathway by Rhizopus delemar in packed bed column fermenter and to compare this degradation metabolism with glass flasks fermentation. The methylxanthines were quantified by HPLC analysis. The experiments were realized with the optimized conditions in previous experiments: pH 6.5, 28ºC, inoculation rate 10(6) spores/g substrate, aeration rate 60 mL/min... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Decaffeination; Fermentation; Caffeine; Theophylline; Bioreactor; Filamentous fungi. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822003000500035 |
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| Del Campo,A.; Bracho,M.; Marcano,L.; Guíñez,J.; De la Torre,C.. |
| This work evaluated the qualitative and quantitative cellular changes induced by treatment with 5-aminouracil (5-AU) and a combination of 5-AU and caffeine in plant cells in relation to DNA damage, repaired damage, and residual damage. As biological material, Allium cepa L. root tips were used, grown in filtered water, in darkness, with aeration at constant temperature of 25 °C ± 0.5. Cell populations were synchronized using 5 mM caffeine in order to study the effects of 5-AU and caffeine/5-AU combined treatment on the DNA content and their incidence in the entrance to mitosis. The results showed a delay in the G2 period due to induced DNA damage by the 5-AU and caffeine/5-AU combined treatment, shown by aberrant metaphases, anaphases and telophases. The... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: 5-aminouracil; G2 checkpoints; Caffeine. |
| Ano: 2005 |
URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0327-95452005000200003 |
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| Marcelain,Katherine; de la Torre,Consuelo; González,Patricio; Pincheira,Juana. |
| Checkpoint response to DNA damage involves the activation of DNA repair and G2 lengthening subpathways. The roles of nibrin (NBS1) and the ATM/ATR kinases in the G2 DNA damage checkpoint, evoked by endogenous and radio-induced DNA damage, were analyzed in control, A-T and NBS lymphoblast cell lines. Short-term responses to G2 treatments were evaluated by recording changes in the yield of chromosomal aberrations in the ensuing mitosis, due to G2 checkpoint adaptation, and also in the duration of G2 itself. The role of ATM/ATR in the G2 checkpoint pathway repairing chromosomal aberrations was unveiled by caffeine inhibition of both kinases in G2. In the control cell lines, nibrin and ATM cooperated to provide optimum G2 repair for endogenous DNA damage. In... |
| Tipo: Journal article |
Palavras-chave: Ataxia-telangiectasia; ATM; ATR kinases; Caffeine; G2 checkpoint; Nibrin (Nbs1); Nijmegen breakage syndrome (NBS). |
| Ano: 2005 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602005000200007 |
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| Deslandes,A.C.; Veiga,H.; Cagy,M.; Piedade,R.; Pompeu,F.; Ribeiro,P.. |
| Caffeine is the most consumed psychoactive substance in the world. The effects of caffeine have been studied using cognitive and motor measures, quantitative electroencephalography (qEEG) and event-related potentials. However, these methods are not usually employed in combination, a fact that impairs the interpretation of the results. The objective of the present study was to analyze changes in electrophysiological, cognitive and motor variables with the ingestion of caffeine, and to relate central to peripheral responses. For this purpose we recorded event-related potentials and eyes-closed, resting EEG, applied the Stroop test, and measured reaction time. Fifteen volunteers took caffeine (400 mg) or placebo in a randomized, crossover, double-blind... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Quantitative electroencephalography; P300; Caffeine; Cognitive and motor measures; Psychostimulants. |
| Ano: 2005 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005000700011 |
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| Fan,Leifa; Soccol,Andréa Thomaz; Pandey,Ashok; Vandenberghe,Luciana Porto de Souza; Soccol,Carlos Ricardo. |
| The objective of this work was to study the effect of caffeine and tannins on Pleurotus sp. cultivation and to evaluate the feasibility of using coffee husks as substrate for mushroom cultivation. Eight strains of P. ostreatus and two strains of P. sajor-caju were screened on a medium prepared from agar extract of coffee husk. Based on best mycelial growth and biomass production, the strain P. ostreatus LPB 09 was selected for detailed studies. With the increase of caffeine concentration, the mycelial growth and the biomass production decreased, and no growth was observed when concentration of caffeine was 2500 mg/L. Furthermore, Pleurotus did not degrade the caffeine, but absorbed it. Tannin under 100 mg/L in the medium stimulated the growth of mycelia,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cultivation; Pleurotus; Caffeine; Tannin; Detoxification. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822006000400003 |
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| Ashihara,Hiroshi. |
| Coffee beans contain two types of alkaloids, caffeine and trigonelline, as major components. This review describes the distribution and metabolism of these compounds. Caffeine is synthesised from xanthosine derived from purine nucleotides. The major biosynthetic route is xanthosine -> 7-methylxanthosine -> 7-methylxanthine -> theobromine -> caffeine. Degradation activity of caffeine in coffee plants is very low, but catabolism of theophylline is always present. Theophylline is converted to xanthine, and then enters the conventional purine degradation pathway. A recent development in caffeine research is the successful cloning of genes of N-methyltransferases and characterization of recombinant proteins of these genes. Possible biotechnological... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Coffea; Caffeine; Purine alkaloids; Pyridine alkaloids; Theobromine; Trigonelline. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1677-04202006000100001 |
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| Registros recuperados: 43 | |
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