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Brief Episode (brief + episode)
Selected AbstractsForced depression of leaf hydraulic conductance in situ: effects on the leaf gas exchange of forest treesFUNCTIONAL ECOLOGY, Issue 4 2007T. J. BRODRIBB Summary 1Recent work on the hydraulic conductance of leaves suggests that maximum photosynthetic performance of a leaf is defined largely by its plumbing. Pursuing this idea, we tested how the diurnal course of gas exchange of trees in a dry tropical forest was affected by artificially depressing the hydraulic conductance of leaves (Kleaf). 2Individual leaves from four tropical tree species were exposed to a brief episode of forced evaporation by blowing warm air over leaves in situ. Despite humid soil and atmospheric conditions, this caused leaf water potential (,leaf) to fall sufficiently to induce a 50,74% drop in Kleaf. 3Two of the species sampled proved highly sensitive to artificially depressed Kleaf, leading to a marked and sustained decline in the instantaneous rate of CO2 uptake, stomatal conductance and transpiration. Leaves of these species showed a depression of hydraulic and photosynthetic capacity in response to the ,blow-dry' treatment similar to that observed when major veins in the leaf were severed. 4By contrast, the other two species sampled were relatively insensitive to Kleaf manipulation; photosynthetic rates were indistinguishable from control (untreated) leaves 4 h after treatment. These insensitive species demonstrate a linear decline of Kleaf with ,leaf, while Kleaf in the two sensitive species falls precipitously at a critical water deficit. 5We propose that a sigmoidal Kleaf vulnerability enables a high diurnal yield of CO2 at the cost of exposing leaves to the possibility of xylem cavitation. Linear Kleaf vulnerability leads to a relatively lower CO2 yield, while providing better protection against cavitation. [source] Activity-based anorexia during adolescence does not promote binge eating during adulthood in female ratsINTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 8 2008Wenli Cai Abstract Objective: Given the frequency of transition from anorexia nervosa to bulimia nervosa, this study investigated whether a history of activity-based anorexia (ABA) during adolescence would promote binge eating during adulthood in female rats. Method: Adolescent rats were given 1-h unlimited access to chow and ad libitum access to a running wheel until body weight reached <80%, indicating the development of ABA. During adulthood, all groups were given 21 days of access to a palatable food for 2 h/day and ad libitum access to chow. Results: During adolescence, rats in the ABA paradigm developed increased wheel running and decreased food intake, reaching <80% of body weight after 3 days. However, there were no significant differences between groups in the amount of binge food consumed during adulthood. Conclusion: A brief episode of ABA during adolescence did not lead to increased binge eating later in life. Longer-term models are needed to determine whether a propensity toward binge eating may result from more sustained ABA during adolescence. © 2008 by Wiley Periodicals, Inc. Int J Eat Disord 2008 [source] Late Quaternary upwelling off tropical NW Africa: new micropalaeontological evidence from ODP Hole 658C,JOURNAL OF QUATERNARY SCIENCE, Issue 3 2006Simon K. Haslett Abstract Planktonic foraminifera and radiolaria have been analysed in a Late Quaternary (40,0,ka) sediment sequence from Ocean Drilling Program (ODP) Hole 658C located under a coastal upwelling system near Cap Blanc, offshore northwest Africa, in order to document the palaeoceanographic history of the area. Temporal variations in species abundance and faunal assemblage analysis reveal a tripartite phased sequence of palaeoceanographic change through the Late Quaternary. Phase 1 spans 40,14.5,ka and is characterised by moderate upwelling, but Heinrich event 2 is distinguished as a brief episode of strengthened upwelling. Phase 2 begins with a change in a number of variables at ca. 14.5,ka and extends to ca. 5.5,ka. This phase is characterised by a general strengthening of upwelling, but may be subdivided into three minor phases including (a) the recognition of the Younger Dryas, marked by a temporary reduction in upwelling strength, followed by (b) an intensification of upwelling, and (c) upwelling and high productivity between 8 and 5.5,ka. This phase of upwelling corresponds with maximum Holocene cooling, possibly triggered by the collapse of the Laurentide ice sheet. Phase 3 extends from 5.5 to 0,ka and is characterised by weak upwelling and significant calcite dissolution. These phases are related to climatic events, particularly the African Humid Period (AHP), which is coincident with Phase 2. The AHP is characterised by increased precipitation, linked to an intensification of the African monsoon that enhances North East Trade Wind-driven coastal upwelling and is associated with the expansion of continental vegetation across North Africa. Copyright © 2006 John Wiley & Sons, Ltd. [source] Coronary Blood Flow Produced by Muscle Contractions Induced by Intracardiac Electrical CPR during Ventricular FibrillationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2009HAO WANG M.D. It has been reported that transthoracic electrical cardiopulmonary resuscitation (ECPR) generates coronary perfusion pressures (CPP) similar to manual chest compressions (MCC). We hypothesized that intracardiac ECPR produces similar CPP. Methods: ECPR pulse train protocols were applied for 20 seconds in a porcine model following 10 seconds of ventricular fibrillation (VF), using a defibrillator housing electrode and a right ventricular coil (IC-ECPR). Each protocol consisted of 200-ms electrical pulse trains applied at a rate of 100 pulse trains/min. The protocols were grouped in skeletal-based versus cardiac-based stimulation measurements. CPP was recorded and compared to historical MCC values generated by a similar experimental design. CPP > 15 mm Hg at 30 seconds of VF following the application of an IC-ECPR protocol was defined as successful. Results: Mean CPP for all intracardiac ECPR pulse train protocols at 30 seconds of VF was 14.8 ± 3.8 mm Hg (n = 39). Mean CPP in seven successful skeletal-based IC-ECPR protocols was 19.4 ± 3.2 mm Hg, and mean CPP in 10 successful cardiac-based IC-ECPR protocols was 17.4 ± 2.1 mm Hg. Reported CPP for 15 MCC experiments at 30 seconds of VF was 22.9 ± 9.4 mm Hg (P = 0.35 compared to skeletal-based IC-ECPR, P = 0.08 compared to cardiac-based IC-ECPR). Conclusions: Intracardiac applied electrical CPR produced observable skeletal muscle contractions, measurable pressure pulses, and coronary perfusion pressures similar to MCC during a brief episode of untreated VF. [source] The ProSealTM laryngeal mask airway in childrenPEDIATRIC ANESTHESIA, Issue 3 2005M. LOPEZ-GIL MD Summary Background :,The ProSealTM (PLMA) is a new laryngeal mask device with a modified cuff to improve the seal and a drain tube to provide access to the gastrointestinal tract. We assessed the performance of the size 2 (which has no dorsal cuff) and size 3 (which has a dorsal cuff) in terms of insertion success, efficacy of seal, tidal volume, gas exchange, fiberoptic position, gastric tube placement and frequency of problems. Methods :,Eighty children undergoing minor surgery were studied (n = 40, size 2 PLMA, weight 10,25 kg; n = 40, size 3 PLMA, weight >25,50 kg). Induction was with remifentanil and propofol. Insertion was with the introducer tool and by experienced users. Maintenance was with propofol or sevoflurane and pressure controlled ventilation. Results :,The first-time and overall insertion success rate was 84 and 100%, respectively. Oropharyngeal leak pressure was 31 ± 5 cmH2O. There were no gastric or drain tube air leaks. Tidal volume and gas exchange was adequate in all patients, other than two brief episodes of hypoxia because of airway reflex activation. The vocal cords and epiglottis were visible in 99 and 80%, respectively, via the airway tube. The first-time and overall insertion success rate for gastric tube insertion was 87 and 100%, respectively. During maintenance, the PLMA was removed in one patient with airway reflex activation and another required epinephrine for bronchospasm. There were no differences in performance between the sizes 2 and 3 PLMA. Conclusion :,The PLMA is an effective airway device in children and isolates the glottis from the esophagus when correctly positioned. Despite the lack of a dorsal cuff, the performance of the size 2 was similar to the size 3 PLMA in the age groups tested. [source] Transcatheter closure of patent foramen ovale during a radiofrequency ablation procedureCLINICAL CARDIOLOGY, Issue 8 2006Antonis S. Manolis M.D. Abstract A 43-year-old woman was undergoing radiofrequency catheter ablation of a symptomatic supraventricular tachycardia when a patent foramen ovale (PFO) was detected with passage of the diagnostic electrocatheter into the left atrium. Prior echocardiographic studies had been unrevealing. Upon questioning during the procedure, the patient now admitted to frequent and disabling daily migraine attacks, while her family described two recent brief episodes of disorientation and dysarthria, consistent with transient ischemic attacks. The patient was informed of the option of future closure of the PFO, but she insisted on having this done concurrently with her ablation procedure. After successful ablation of the slow pathway considered responsible for the supraventricular tachycardia, an Amplatzer closure device was utilized and the PFO was successfully closed during the same procedure. A postprocedural transesophageal echocardiogram showed complete sealing of the PFO, while over the ensuing 10 months the patient reported virtual elimination of her daily attacks of migrainous headaches, limited to a single episode the day after the procedure and none thereafter. [source] | ||||||||||