نتایج جستجو برای: caffeine
تعداد نتایج: 11294 فیلتر نتایج به سال:
Caffeine is widely consumed and well known for stimulating the central nervous system. When developing new foods and beverages that contain caffeine, it is important to explore the potential synergistic effects of consuming amino acids and other food ingredients with caffeine on humans. Given the physiological pathways affected by the amino acid ornithine, consumption of ornithine with caffeine...
Large individual differences characterize the changes induced by sleep deprivation on neurobehavioral functions and rhythmic brain activity. To investigate adenosinergic mechanisms in these differences, we studied the effects of prolonged waking and the adenosine receptor antagonist caffeine on sustained vigilant attention and regional electroencephalogram (EEG) power in the ranges of theta act...
Caffeine enhancement of chemical carcinogen-induced transformation of cultured Syrian hamster cells.
depends upon: (a) concentration of caffeine; (fc) time of addition of caffeine; (c) length of exposure; and (d) carcinogen used. The addition of caffeine to cells treated 1 hr previously with carcinogen resulted in the potentiation of toxicity. Toxicity increased with caffeine concentration and length of exposure to carcinogen-containing medium. With 50 ¿ig caffeine per ml medium for 2 days cl...
the purpose of present study was to examine the effect of caffeine consumption on substrate metabolism and time to exhaustion during exercise and one hour after exercise in athletic female. eleven female athlete students (age 23±1.54 years, body weight 56.09±5.99 kg, and aerobic power 40.21±1.01ml/kg/min) volunteered and were randomly divided into three groups of control,placebo (starch capsule...
BACKGROUND While high doses of caffeine may affect pulmonary function and bronchial challenge tests in patients with mild asthma, the effects of lower doses (< or = 5 mg/kg) are less well documented. Specific recommendations exist for withholding theophylline, but not caffeine, before bronchoprovocation and pulmonary function testing. METHODS To assess the effect of a single oral dose of caff...
Both the methylxanthine caffeine and the heavy subunit of ferritin molecule (FHC) are able to control the proliferation rate of several cancer cell lines. While caffeine acts exclusively as a negative modulator of cell proliferation, FHC might reduce or enhance cell viability depending upon the different cell type. In this work we have demonstrated that physiological concentrations of caffeine ...
Caffeine, as an oocyte aging inhibitor, was used in many different species to control or delay oocyte aging. However, the safety of caffeine and developmental competence of aged oocytes inhibited by caffeine has not been studied systematically. So we detected the spindle morphology, distribution of cortical granules, zona pellucida hardening and pronucleus formation to assess oocyte quality of ...
The indiscriminate use of caffeine by people of all ages may present health hazards. The public at large needs to be more informed of the presence of caffeine in commonly consumed foods and beverages, particularly by infants, children and pregnant women. It is the responsibility of all consumers to investigate the caffeine content of suspected products so that intake may be objectively monitore...
Research reports on pulmonary function measurements often mention caffeine abstinence as a condition for testing subjects. Yet, the effects of caffeine on respiration are not well documented. This study was intended to investigate the physiological effects of caffeine on respiratory resistance measurements and the necessity of caffeine avoidance in such testing. Thirty-one subjects were adminis...
BACKGROUND Caffeine stimulates calcium-induced calcium release (CICR) in many cell types. In neurons, caffeine stimulates CICR presynaptically and thus modulates neurotransmitter release. METHODOLOGY/PRINCIPAL FINDINGS Using the whole-cell patch-clamp technique we found that caffeine (20 mM) reversibly increased the frequency and decreased the amplitude of miniature excitatory postsynaptic cu...
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