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Third Hour (third + hour)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Short-term homeostasis of REM sleep assessed in an intermittent REM sleep deprivation protocol in the rat

JOURNAL OF SLEEP RESEARCH, Issue 1 2002
ADRIÁN OCAMPO-GARCÉS
An intermittent rapid eye movement (REM) sleep deprivation protocol was applied to determine whether an increase in REM sleep propensity occurs throughout an interval without REM sleep comparable with the spontaneous sleep cycle of the rat. Seven chronically implanted rats under a 12 : 12 light,dark schedule were subjected to an intermittent REM sleep deprivation protocol that started at hour 6 after lights-on and lasted for 3 h. It consisted of six instances of a 10-min REM sleep permission window alternating with a 20-min REM sleep deprivation window. REM sleep increased throughout the protocol, so that total REM sleep in the two REM sleep permission windows of the third hour became comparable with that expected in the corresponding baseline hour. Attempted REM sleep transitions were already increased in the second deprivation window. Attempted transitions to REM sleep were more frequent in the second than in the first half of any 20-min deprivation window. From one deprivation window to the next, transitions to REM sleep changed in correspondence to the amount of REM sleep in the permission window in-between. Our results suggest that: (i) REM sleep pressure increases throughout a time segment similar in duration to a spontaneous interval without REM sleep; (ii) it diminishes during REM sleep occurrence; and (iii) that drop is proportional to the intervening amount of REM sleep. These results are consistent with a homeostatic REM sleep regulatory mechanism that operates in the time scale of spontaneous sleep cycle. [source]

QTc interval and QTc dispersion during haemodiafiltration

NEPHROLOGY, Issue 6 2004
FULVIO FLOCCARI
SUMMARY: Background and Aim: Our aim was to evaluate QTc interval and QTc dispersion in 27 end-stage renal disease (ESRD) patients undergoing Acetate Free Biofiltration (AFB) in order to ascertain any correlations between the electrrocardiographic (ECG) parameters, serum Na+, K+, Ca++, Mg++ and intraerythrocytic Mg++ (Mg++e) concentrations. All measures were made at t0 (session beginning), t1 (first hour), t2 (second hour), t3 (third hour), and t4 (session end). Results: Blood pressure, heart rate, bodyweight and total ultrafiltration in the three dialysis sessions were constant. A significant progressive increase occurred in serum Ca++ during the sessions, while there was a significant diminution in serum K+. The pattern for Mg++ concentrations in serum and erythrocytes differed: in serum it decreased, whereas Mg++e increased. At t4, the QTc interval was reduced to a significant extent with respect to the baseline value. QTc dispersion significantly increased at t1 without there being significant variations at other times with respect to t0. At t2, t3 and t4, values promptly returned to baseline levels. QTc had a negative correlation with serum Ca++ levels at t4. In contrast, an inverse correlation was found between QTc dispersion and serum K+ at t1. No other correlations could be found between any other electrolytes, QTc interval or QTc dispersion. Conclusion: In conclusion, the decrease observed in the QTc interval at the end of an AFB session was inversely related to serum Ca++ concentrations. Moreover, an increase in QTc dispersion occurred during the first hour of the session, and was negatively correlated with serum K+. [source]

Comparison of ethanol and methanol crossover through different MEA components and structures by cyclic voltammetry

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009
J. Ling
Abstract The crossover rate of ethanol or methanol through membrane electrode assembly (MEA) and MEA components was studied quantitatively at 25 and 60 °C by cyclic voltammetry method. The results obtained in this work show that cyclic voltammetry is a powerful technique to assess the crossover phenomenon through MEA components and structures. In all cases, the ethanol crossover rates are lower than those of methanol. The ethanol and methanol crossover rates depend upon time and temperature. For an initial concentration of 1 M of ethanol or methanol, the crossover rate increases to a maximum after the first hour of the cell operation and then decreases gradually to a certain concentration after the third hour. At 60 °C, the maximum concentration of ethanol crossover rate is lower than that obtained at 25 °C. The crossover rate of ethanol or methanol through MEA is lower than through the components alone (pressed or nonpressed membranes or gas diffusion electrode). Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Effect of infants' position on serum bilirubin level during conventional phototherapy

ACTA PAEDIATRICA, Issue 8 2010
ML Donneborg
Abstract Aim:, To compare the decrease in total serum bilirubin (TSB) concentration during conventional phototherapy in infants treated in supine position exclusively versus infants alternated between exposure in supine and prone position every third hour. Moreover, to survey current practice patterns in two Scandinavian countries as far as alternating exposure. Methods:, A total of 112 infants with non-haemolytic hyperbilirubinaemia, but otherwise healthy, and a gestational age ,33 weeks were randomized to one of the treatment groups. All infants received phototherapy for 24 h. TSB was measured at start of phototherapy and after 12 and 24 h of treatment. Questionnaires about routines for position changes in infants during phototherapy were sent to all 41 neonatal departments in Denmark and Norway. Results:, No statistically significant differences in the decrease in TSB were observed between the two treatment groups: at 12 h of therapy, TSB decreased 32% in both groups and at 24 h 49% and 50%, respectively. In two-thirds of Danish and Norwegian departments, the infants were routinely turned during phototherapy, most often every third hours. Conclusion:, The decrease in TSB was not significantly associated with positioning of the infant during conventional phototherapy. Alternating exposure is widely practiced in Scandinavia but is unnecessary. [source]