The acute effect of a single−dose of caffeine on the P300 event−related brain potential (ERP) was assessed in a study using a repeatedly presented auditory oddball button−press task. A dose (5mg/kg body−weight) of either caffeine or placebo lactose, dissolved in a cup of decaffeinated coffee, was administered double−blindly to coffee drinkers who had abstained from coffee for 24hrs, with the presentation order of the sessions counterbalanced and separated by 2−4 weeks. The caffeine−treatment condition demonstrated a smaller P300 amplitude and a shorter latency overall than the placebo treatment condition. The mean P300 amplitude value difference (caffeine minus placebo) increased with the successive trial blocks. Caffeine ingestion appears to yield a lower resource−consumption and a net increase in allocating attention resources for task performance across repeated measurements.
Caffeine ; Acute ; Caffeine Measurement ; Placebos ; Measured

PURPOSE: This study analyzed the degree of job stress and caffeine intake in workers in industrial positions in order to determine the relationships between job stress and caffeine intake. METHODS: For this purpose, this study conducted a survey targeting 361 blue collar workers working for K manufacturing company, Gwangju. RESULTS: The total score for job stress in subjects was 72.7 ± 6.8 points/100 points. According to job stress, subjects were categorized as follows: Q1 for the group who had the least stress; Q2 for the group who had little stress; Q3 for the group who had a lot of stress, and Q4 for the group who had the most stress. As for the effects of caffeine on health, 57.1% thought that caffeine is helpful and not harmful if taken properly while 17.3% responded that less caffeine consumption is better. Daily intake of caffeine according to stress was presented as: 172.0 ± 85.3 mg in Q1, 179.0 ± 83.7 mg in Q2, 187.9 ± 81.4 mg in Q3, and 214.2 ± 147.3 mg in Q4 (p < 0.05). The percentages of caffeine consumption compared to the daily safe limit in subjects were: 43.0 ± 21.3, 44.8 ± 20.9, 47.1 ± 20.4, and 53.6 ± 36.8% in Q1, Q2, Q3, and Q4, respectively (p < 0.05). Adverse effects such as nausea or vomiting from caffeine were most common in Q4 (p < 0.05) CONCLUSION: As a result, higher stress in blue collar workers working for K manufacturing company was associated with more caffeine consumption. Groups with a lot of stress (Q4) consumed approximately 50% of daily safe limit of caffeine. Considering the results above, this study suggests that further research on more precise caffeine intake and its effects is needed.
Caffeine* ; Gwangju ; Nausea ; Vomiting

No abstract available.
Caffeine* ; HeLa Cells* ; Humans

No abstract available.
Animals ; Caffeine* ; Mice* ; Mitomycin*

No abstract available.
Adolescent* ; Caffeine* ; Humans

OBJECTIVE: To evaluate the effect of caffeine on balance control of hemiparetic stroke patients, we investigated the difference in postural stability before and after drinking coffee by observing changes in stability index (SI) from posturography. METHODS: Thirty patients with history of stroke and 15 age-matched healthy subjects participated in this study. Effect of group factor (of the control and stroke groups) and treatment factor (pre- and post-drinking of coffee) on SI were tested in three conditions: with eyes opened, with eyes closed, and with a pillow support. The effects of these factors on visual deprivation and somatosensory change of subjects were also tested. RESULTS: Under all conditions, SI was higher in the stroke group than in the control group. Under eyes-open condition, the treatment factor was not statistically significant. Under eyes-closed condition, the interaction between group and treatment factor was statistically significant. After the subjects drank coffee, SI in the control group was increased. However, SI in the stroke group was decreased. Under pillow-supported condition, the interaction between group and treatment factor appeared marginally significant. For visual deprivation effect, the interaction between treatment and group factor was statistically significant. After caffeine consumption, the visual deprivation effect was increased in control group but decreased in the stroke group. For somatosensory change effect, the interaction between group and treatment factor was not statistically significant. CONCLUSION: Postural stability of hemiparetic stroke patients related to somatosensory information was improved after intake of usual dose of caffeine.
Caffeine* ; Coffee ; Drinking ; Humans ; Stroke*

Cope brand of aspirin-caffeine ; Health Personnel ; Community

The effects of nifedipine, a dihydropyridine Ca2+ antagonist, on the eleetrically-evoked twitch response, train-of-four and tetanic stimulation were studied in the isolated rat hemidiaphragm preparation. Nifedipine, in concentrations ranging from 3 to 100 uM, increased the electrically-evoked (nerve stimulation, 0.1 Hz, 0.5 ms, 10 V) twitch response and train-of-four ratio in a dose-relat- ed fashion, and the potentiating effects were inhibited by d-tubocurarine preteratment. The effect of nifedipine was not affected by reducing the extracellular Ca2+ concentration from 2.5 mM to 1.25 mM. In cases of the direct(muscle, 0.1 Hz, 5 ms, 10 V) stimulation, nifedipine increased the twitch response in a dose-dependent manner, but the amplitudes were smaller than those in indirect stimulation. Nifedipine 30 uM potentiated the contractile response induced by 70 mM KC1 and caffeine(10 mM)-induced isometric contractile responses were markedly potentiated by nifedipine treatmeat. Nifedipine 70 upotentiated the effect of l mM caffeine on the electrically-evoked twitch response and the potentiating effect was also seen in reverse treatment. On the basis of these findings, the result of present study suggests that the potentiating contractile response by nifedipine is mediated by two distinctive mechanisms. One is the acetylcholine release from presynaptic nerve terminal and the other may be due to the releases of Ca2+ in sarcoplasmic reticulum.
Acetylcholine ; Animals ; Caffeine ; Nifedipine* ; Rats* ; Sarcoplasmic Reticulum ; Tubocurarine

OBJECTIVE : Modafinil, methylphenidate, and caffeine are wakefulness-promoting substances. Previously, it was reported that caffeine-induced wakefulness differs from natural wakefulness in terms of the EEG spectral profiles. In order to evaluate whether wakefulness induced by other psychostimulants differs from both caffeine-induced and natural wakefulness, we examined the effects of the psychostimulants on sleep-wake architecture and EEG spectral profiles. METHODS : Eighteen Sprague-Dawley male rats underwent an EEG/EMG recording session from 10 : 30 to 17 : 30. They received caffeine (7.5, 15, 30 mg/kg i.p.), methylphenidate (1, 2, 5, 10 mg/kg i.p.) or modafinil (5, 10, 25, 50, 100 mg/kg i.p.) at 13 : 30. The number, total duration, and average duration of sleepwake states were obtained. EEG band powers were calculated by spectral analysis. Frequency bands were divided into the following ranges : D1, 1-2.5 Hz ; D2, 2.5-4.5 Hz ; T1, 4.5-7 Hz ; T2, 7-10 Hz ; SI, 10-14 Hz ; B1, 14-22 Hz ; B2, 22-34 Hz ; GA, 34-50 Hz. RESULTS : All three psychostimulants significantly and dose-dependently increased active wake duration and decreased slow-wave sleep. Equipotent doses of caffeine, methylphenidate, and modafinil for increasing active wake and decreasing slow-wave sleep were 7.5 mg/kg, 10 mg/kg, and 100 mg/kg, respectively. In equipotent doses, an increase of active wake duration by caffeine and methylphenidate was attributed to increases of both frequency and average duration of active wake state, whereas increase of active wake duration by modafinil was attributed to increase of average duration of active wake state only. In equipotent doses, caffeine and methylphenidate decreased the power of lower frequency bands (1-22 Hz), whereas modafinil did not. During slow-wave sleep, modafinil and methylphenidate increased the power of lower frequency bands, but caffeine did not. All the psychostimulants increased the power of the GA band, which was more prominent in the frontal cortex than the parietal cortex. CONCLUSION : These results suggest that moda-nil-induced wakefulness differs from caffeine- or methylphenidate-induced wakefulness in terms of EEG spectral profiles and sleep-wake architecture.
Animals ; Benzhydryl Compounds ; Caffeine ; Electroencephalography ; Humans ; Male ; Methylphenidate ; Rats ; Wakefulness

OBJECTIVES: Individuals differ in their biological rhythms. This study investigated the association between the morningness-eveningness and sleep patterns, daytime sleepiness and fatigue in Korean male adolescents. METHODS: Participants were 501 eleventh grade male students (16.9+/-0.2 years of age) in one male high school in Seoul. Each student completed the Korean translation of composite scale (KtCS), Epworth sleepiness scale (ESS), Fatigue Severity Scale (FSS) and a questionnaire about their sleep schedule. RESULTS: The evening group had shorter weekday sleep time than the intermediate (p<0.001) or morning group (p=0.029). The evening group had more daytime napping (16.8%, p<0.001), high rate of caffeine use (58.8%, p<0.001) and snoring (18.5%, p=0.037). The evening group showed more daytime sleepiness (8.7, SD=3.2, p<0.001) and severe fatigue (4.4, SD=1.2, p<0.001) than the intermediate or morning group. CONCLUSION: Adolescents with eveningness have higher problems in weekday sleep, daytime sleepiness and fatigue. An intervention program for sleep problem in these adolescents should be considered.
Adolescent ; Caffeine ; Fatigue ; Humans ; Male ; Surveys and Questionnaires ; Snoring