Biomedical subjects

P Badia

Publications and source records attributed to P Badia.

At least 37 records · Page 2Linked to original sources

PubMed1993

Immediate effects of different light intensities on body temperature and alertness.

The effects of different light intensities on temperature and alertness were investigated. It was hypothesized that temperature and alertness would be affected by certain light intensities but only during the melatonin release period (after 2100 h). Fifteen subjects were tested under three levels of light known to suppress melatonin (500, 1000, and 5000 lx) and a level known not to affect melatonin (50 lx). Subjects were tested on four occasions from 1700 until 2300 h. Tympanic temperature and measures of alertness (EEG power and frequency and self-reports) were obtained before and after melatonin onset. There were no differences in any measure prior to the melatonin onset, increases in temperature and alertness occurred only after melatonin onset. Temperatures and self-reported alertness scores obtained under light intensities of 500, 1000, and 5000 lx were elevated relative to those obtained under 50 lx but were not significantly different from each other. The results suggest that melatonin may be involved in mediating the effects of light on temperature and alertness and that 500 lx may be near the threshold for significant melatonin suppression, temperature enhancement, and increases in alertness.

Adult↗

PubMed1992

Time of day and semantic category effects on late components of the visual ERP.

The N100, P200, N400 and P600 components of the visual event-related potential were recorded from 11 female subjects every 2 h from 09:00 to 21:00 hours using a semantic categorization task. All subjects scored as "Intermediate" or marginal "Evening" types on a Morningness-Eveningness questionnaire. Amplitude and latency of components, tympanic temperature, and performance measures for positive and negative category instances were assessed. Amplitude of P200 increased across the day. Amplitude of N400 was larger, and latency of P600 was longer, for negative category instances, but neither component varied with time of day. N100 was unaffected by time of day. The results suggest that previous reports of diurnal variations in visual N100-P200 were due to variations in P200 alone, and that diurnal variations in P200 may reflect diurnal variations in underlying arousal levels. In addition, overlap with P600 may have obscured time of day effects for N400.

Adolescent↗

PubMed1992

Time-of-night patterns in PLMS activity.

Time-of-night patterns for periodic leg movement in sleep (PLMS) activity were assessed in 72 patients diagnosed as having PLMS (46 with only PLMS, 10 with narcolepsy and PLMS and 16 with sleep apnea and PLMS). Two distinct patterns of PLMS activity were identified. For one pattern, PLMS activity was high initially upon falling asleep and then decreased across the remainder of the night with the majority of the activity occurring during the first half of the night. For the second pattern, PLMS activity was relatively evenly distributed across the night with slightly greater activity in the middle of the night. These patterns were highly reliable across two nights of recording for group 1 and less so for group 2 even though there was significant variability between nights in the number of PLMS. Patients in group 2 were younger (except for those with sleep apnea) and were sleepier during the day. Implications of these findings for pharmacologic management are discussed.

Adult↗

PubMed1991

Motor responsiveness to stimuli presented during sleep: the influence of time-of-testing on sleep stage analyses.

The relationship between time-of-night of testing (circadian factors) and motor responsiveness to stimuli presented during different stages of sleep was examined. Nine males slept for two nonconsecutive nights in the laboratory. On Night 1, tympanic temperature was assessed at 30 min intervals. On Night 2, responsiveness was assessed with an incremental series of tones presented in sleep stages 2, 3/4, and REM throughout the night. Subjects were instructed to make a microswitch closure to the tones. Results showed that for all stages, responsiveness decreased across thirds of the night. Because the distribution of each sleep stage differed across the night, the effects on responsiveness due to time-of-testing and to sleep stage were confounded. When time-of-testing was held constant, responsiveness was greater in stages 2 and REM than in stage 3/4. When time-of-testing was not held constant, effects nearly opposite of the latter could be demonstrated.

Arousal↗

PubMed1991

Bright light effects on body temperature, alertness, EEG and behavior.

The immediate psychophysiological and behavioral effects of photic stimulation on humans [bright light (BL) of 5K lux or dim light (DL) of 50 lux] were assessed in male subjects (N = 43) under four different conditions. For one condition the same subjects (N = 16) received alternating 90-min blocks of BL and DL during the nighttime h (2300-0800 h) under sustained wakefulness conditions. A second condition was similar to the first except that subjects (N = 8) received photic stimulation during the daytime hours. For the third and fourth conditions different subjects received either continuous BL (N = 10) or continuous DL (N = 9) during the nighttime hours. For the nighttime alternating condition body temperature decreased under DL but either increased or maintained under BL. For the continuous light condition, body temperature dropped sharply across the night under DL but dropped only slightly under BL. Sleepiness was considerably greater under DL than under BL, and the difference became larger as the night progressed. Similarly, alertness, measured by EEG beta activity, was greater under BL, and nighttime performance on behavioral tasks was also generally better. There were no differential effects between BL and DL on any measure during the daytime. These data indicate that light exerts a powerful, immediate effect on physiology and behavior in addition to its powerful influence on circadian organization.

Adolescent↗

PubMed1991

Temperature, time-of-night of testing, and responsiveness to stimuli presented while sleeping.

The present study examined how time-of-night of testing and body temperature related to responsiveness to stimuli presented in sleep. Nine males slept for two nonconsecutive nights in the sleep laboratory. On Night 1, tympanic temperature was assessed at 30-min intervals. On Night 2, responsiveness was assessed with an incremental series of tones (5dB steps) presented in sleep stages 2, 3/4, and REM throughout the night (0030-0800 h). Subjects were instructed and given practice prior to sleep to make a microswitch closure to the tones. Results showed a curvilinear pattern of responsiveness across the night in that the intensity of tones required for a response increased until about 0530 h, then decreased thereafter. This pattern of responsiveness was positively related to the circadian rhythm of body temperature. A close correspondence was also found between the temperature trough and the performance trough (both occurred at about 0530 h). A greater emphasis on circadian factors may help understand previously reported but contradictory findings. The present results also suggest that measures of responsiveness follow a circadian pattern regardless of the sleep/wake state.

Adult↗

PubMed1991

Systemic and splanchnic hemodynamic effects of molsidomine in rats with carbon tetrachloride-induced cirrhosis.

Molsidomine, a long-acting vasodilator mainly used as an antianginal agent, was reported to decrease the portohepatic venous pressure gradient in patients with alcoholic cirrhosis. This study investigated the effects of linsidomine, the active metabolite of molsidomine, on systemic and splanchnic hemodynamics in rats with CCl4-induced cirrhosis using the microsphere technique. Compared with placebo-treated rats, linsidomine-treated animals were found to have a significant decrease in portal venous pressure (-18%, p less than 0.01) and in mean arterial pressure (-16%, p less than 0.01), smaller peripheral resistances (p less than 0.01), greater portal venous inflow (p less than 0.05), smaller splanchnic arteriolar resistances (p less than 0.01) and smaller protocol-lateral resistances (p less than 0.05). Cardiac output, hepatic arterial blood flow, portal blood flow and estimated hepatic blood flow were not significantly different between the two groups of animals. Linsidomine-treated rats exhibited a trend toward greater collateral blood flow compared with controls, but this difference was not significant. We conclude that linsidomine decreases portal venous pressure by reducing portocollateral resistances without affecting liver blood flow. These effects should be beneficial for patients with cirrhosis and portal hypertension.

Animals↗

PubMed1990

Time of day, repeated testing, and interblock interval effects on P300 amplitude.

Time of day, repeated testing, and interblock interval effects on P300 amplitude were investigated. Subjects (N = 50) were tested using a standard oddball paradigm in either morning or afternoon sessions consisting of six test blocks per session. Amplitude of P300 was significantly higher in the morning than in the afternoon for all test blocks. In addition, amplitude of P300 habituated across test blocks from a mean of 9.59 microV on Block 1 to a mean of 4.98 microV on Block 6. Inserting a one-hour interval between Blocks 2 and 3 attenuated the rate of habituation. The results indicate that time of day, repeated testing, and interblock intervals affect P300 amplitude. Amplitude changes due to time of day may reflect circadian variations in cognitive resources indexed by the P300 component, while decrements due to repeated testing may reflect changes in allocation of resources across test sessions.

Adult↗

PubMed1990

Responsiveness to olfactory stimuli presented in sleep.

Whether humans react to olfactory stimuli presented in sleep was assessed. Responses of ten participants (mean age = 22.8 years) were recorded to repeated three-minute periods of either air alone or to a peppermint odor (0.26 mg/liter) during stage 2 sleep. These responses included behavioral (awakening, microswitch closure), autonomic (heart rate, EMG, respiration), and central (EEG) components. An odor delivery system is described comprised of an aquarium pump, Teflon and TYGON tubing, oxygen mask, filtering, and air flow valves. The data indicate that humans react behaviorally, autonomically and centrally to olfactory stimuli presented while sleeping. Although the percentage of overall responsivity to olfactory stimuli was low, significant differences (ANOVA) in responsivity to odor periods vs. nonodor periods were found for microswitch closures, EEG, EMG, and heart rate. For these measures eight or more of the ten participants showed this pattern of differential responsivity during odor and nonodor periods (Sign test = p less than 0.05). A time-of-night effect was also observed in that responsivity tended to be greatest early in the night. The effect on responsivity of other durations, concentrations, and odors requires additional research.

Adult↗

PubMed1990

Ultradian rhythms in responsiveness to stimuli presented during sleep.

The present study examined rhythmicity in responding to stimuli presented during sleep. Subjects were trained while awake to respond (by taking a deep breath) to an auditory stimulus that was subsequently presented after every 4 min (8 subjects) or after every 1 min (8 subjects) of continuous sleep. Visual inspection of the response data revealed, for most subjects, a tendency for response latencies to vary rhythmically with 3-5 response cycles per night. Relatively slow, "time-of-night", changes in responsiveness were also seen. Spectral analysis supported the observation of response rhythmicity. Frequency bands with centers corresponding to periods of 133, 100, and 80 min accounted for a significant proportion of the spectral variance for both the 4-min and 1-min group. Sleep was severely disrupted under the 1-min condition, but response rhythmicity was as evident as under the 4-min condition. For subjects having nearly normal sleep structure, the longer latencies in the response cycles tended to occur during nonrapid eye movement periods, while the shorter latencies tended to occur near REM. Response variability during REM often obscured cyclic tendencies. The data suggest that responsiveness during sleep

Acoustic Stimulation↗

PubMed1990

Behavioral responsiveness in sleeping older adults.

The control of behavior by stimuli presented during sleep, and related effects on sleep and daytime sleepiness, were investigated in 17 older (age = 60-74 years) adults. Experimental subjects (N = 8) were trained while awake to terminate tone presentations by taking a deep breath. Tones were then presented following sleep onset for four consecutive nights with a mean intertone interval of 4 min. Control subjects (N = 9) slept in the laboratory but did not receive tones. The daytime sleepiness of both groups was assessed by recording latency to sleep onset in a morning and afternoon nap test. It was found that the experimental subjects responded reliably to the tones. Responding, however, was almost invariably accompanied by disruption of sleep and overall sleep structure was markedly altered. Surprisingly, the daytime sleepiness of experimental subjects was not reliably greater than that of control subjects.

Aged↗

PubMed1989

Habituation of P300 to target stimuli.

Two experiments examined the effects on N100, N200, and P300 of 1) repeated target presentation, 2) interblock intervals, 3) knowledge of session end, and 4) reversal of targets and nontargets. In the first experiment, subjects (N = 40) performed an oddball task across six test blocks (35 targets per block). Statistical analyses showed that repeated target presentation resulted in P300 amplitude decreases (habituation) and P300 latency increases within and across test blocks (11.3 microV to 5.4 microV, 330 msec to 348 msec), and also resulted in N200 amplitude increases within blocks and N200 latency increases within and across blocks. Interblock intervals resulted in partial recovery of these habituation effects. Knowledge of session end increased P300 amplitude, while reversal of targets and nontargets had no effect. The latencies of N200 and P300 were positively correlated (r .55), while the amplitudes were not. The second experiment demonstrated P300 habituation at multiple scalp sites (Fz, Cz, Pz). Two factors that may relate to habituation of the P300 are decreased arousal level and degree of involvement in the task.

Adolescent↗

PubMed1988

Behavioral control of abnormal breathing in sleep.

Behavioral control of abnormal breathing in sleep was studied to determine if an intervention procedure could reduce apnea duration and also SaO2 (blood oxygen) desaturation levels. Sleep apnea patients (n = 11) were instructed while awake that tones would be presented in sleep whenever an apnea event occurred. They were told to breathe deeply to the tones and were given practice in doing so. Intervention and nonintervention hours alternated across 2 nights following 2 baseline nights. As expected, during the intervention hours, the duration but not the frequency of apneic events was reduced. The procedure also resulted in higher SaO2 levels during the intervention hours. Daytime sleepiness was not greater following intervention but sleep staging effects were observed. The results are sufficiently promising to warrant additional research.

Adult↗

PubMed1988

The P300 component in sleep.

The present investigation utilized the P300 component of the auditory evoked potential as an index of information processing (discrimination) in sleep. Auditory evoked potentials were recorded to target and nontarget stimuli during sleep stages 3/4, 2 and REM under two probability conditions. Corresponding "nontone" waveforms were generated in each sleep stage, representing averaged EEG activity with no tones presented. Target P300 amplitude was higher than both corresponding "nontone" targets and tone nontargets. Probability did not affect the target-nontarget relationship. Latency of P300 increased and amplitude decreased from wakefulness through sleep; however, neither amplitude nor latency differed among sleep stages. Amplitude and latency of N200 increased during sleep. While N200 amplitude was highest in Stage 3-4, N200 latency did not differ among sleep stages. These findings suggest that the P300 recorded in sleep indexes similar cognitive processes as the P300 recorded in wakefulness. That P300 as well as N200 latency increased in sleep suggests that processes indexed by these components may slow during sleep.

Adolescent↗

PubMed1988

The role of aldosterone in water and electrolyte transport across the colonic epithelium of the lizard, Gallotia galloti.

1. The effects of D-aldosterone on the electrical properties and ionic transport have been analysed (in vitro) in the colonic epithelium of the lizard, Gallotia galloti. 2. The injection of 30 g of D-aldosterone induced a significant rise of plasma aldosterone concentration, sustained for 4 hr after administration. 3. Intraperitoneal injections of D-aldosterone caused a slight reduction of transmural potential difference (PD) and short-circuit current (Isc). 4. Net absorption of Na+ across the colon from aldosterone-treated lizards did not increase when compared to colon from normal lizards. Cl- absorption was increased in treated lizards. 5. Addition of mucosal barium to treated tissues brought about a sustained increase of PD and Isc. 6. The absorption of fluid in normal lizards was reversed to fluid secretion in treated lizards. 7. The effects of D-aldosterone on lizard colon are compared with those reported for the colon of mammals and birds.

Aldosterone↗

PubMed1988

Relationship between sleep inertia and sleepiness: cumulative effects of four nights of sleep disruption/restriction on performance following abrupt nocturnal awakenings.

Performance deficits are usually evident following both extended wakefulness (sleep deprivation effects) and immediately upon awakening from sleep (sleep inertia effects). In order to determine whether sleep inertia effects are qualitatively different from sleep deprivation effects, performance on addition tests, Stanford Sleepiness Scale (SSS) ratings, and return-to-sleep latencies (RSLs) were assessed during four nights of sleep disruption/restriction. Eight subjects were polygraphically monitored in the sleep laboratory for five consecutive nights, from 2400 to 0700. On the last four nights (after an adaptation night) subjects were awakened at 0040, 0140, 0240, 0340, 0440, and 0540 for a 20-min test session. Sleepiness ratings and performance on 5-min addition tests were measured at 1.5, 7.5, and 13.5 min post-awakening, and RSL was measured at the end of each test session. Analysis of addition test performance across nights revealed that both speed and accuracy of calculations were adversely affected by the sleep disruption/restriction procedure, indicating that increasing sleepiness exacerbates sleep performance deficits upon awakening. Although divergence of SSS ratings and addition test performance across nights was suggestive, there was no conclusive evidence that sleep inertia is qualitatively different from "typical" sleepiness.

Adolescent↗

PubMed1988

Cognitive activity in sleep and responsiveness to external stimuli.

The relationship between responsiveness to auditory stimuli presented during sleep and cognitive activity during sleep was assessed. Sixteen college-aged women were instructed while awake to turn off a tone by taking a deep breath. The tone was then presented during Stage 2 and REM sleep. Subjects were awakened after select trials to assess the relationship between responding and reports of ongoing cognitive activity. Consistent with the view that cognitive activity reduces responsiveness, significantly fewer responses were found on report (cognitive activity) trials relative to no-report (no cognitive activity) trials in analyses involving all trials and Stage 2 trials alone. Trained judges then rated the subjects' reports of cognitive activity as indicating incorporation or not indicating incorporation of the tone and/or the breathing response. Incorporation was associated with a reduced likelihood of responding relative to no incorporation in analyses involving all trials. No difference in responding was found between no-incorporation trials and no-report trials, suggesting that reduced responsiveness is associated with cognitive activity only when incorporation occurs. These findings support hypotheses that the reduced responsiveness to external stimulation during sleep is at least in part due to ongoing cognitive activity.

Adolescent↗

PubMed1987

Mechanisms of transport of Na+ and Cl- in the lizard colon.

1. Ionic fluxes of sodium and chloride across lizard colon mucosa were measured and compared with the electrical characteristics of the tissue under voltage-clamped conditions. 2. In a Ringer-bicarbonate solution there was both a net sodium flux (JNanet) and a net chloride flux (JClnet) from mucosa to serosa. The net flux residual (JR) was near zero, indicating that net sodium and chloride transport is the result of an electrically neutral transport mechanism. 3. In the presence of sodium, the net chloride flux was abolished and the short-circuit current (Isc) and the electrical potential difference (PD) were unchanged. In the absence of chloride the net sodium flux was abolished and the short-circuit current and electrical potential difference were not modified. 4. From an analysis of the effects of the inhibitors, furosemide, amiloride and disulfonic stilbene (DIDS), a plausible model was developed to explain the characteristics of sodium and chloride absorption.

Animals↗