Home About us Contact
|
Home About us Contact | ||
|
|
||
Termination
Kinds of Termination Terms modified by Termination Selected AbstractsTERMINATION OF PUPAL DIAPAUSE IN THE BOLLWORM HELICOVERPA ARMIGERA BY PRECOCENE IIINSECT SCIENCE, Issue 4 2001WANG Fang-hai Abstract Precocene II terminated pupal diapause in the bollworm Helicoverpa armigera as 20-hydroxyecdysterone did, whereas juvenile hormone analog ZR-515, cyclic adenosine monophosphate (CAMP), and 5-hydroxytryptamine (5-HT) did not. The results indicate that precocene II affects diapausing pupae in the similar way as what was found in the prepupae of the aphid parasitoids, Aphidius matricariae Haliday and Praon volucre Haliday (Hymenoptera: Aphidiidae). It is suggested that precocene II may affect different kinds of termination of diapause in insects. [source] SUPERIOR TERMINATION OF PREGNANCY COMMITTEES , ARE WE DOING THE RIGHT THING?BIOETHICS, Issue 5 2009ASAF TOKER No abstract is available for this article. [source] Cardiac natriuretic peptides and continuously monitored atrial pressures during chronic rapid pacing in pigsACTA PHYSIOLOGICA, Issue 2 2000Changes in atrial natriuretic peptide (ANP), N-terminal proatrial natriuretic peptide and brain natriuretic peptide (BNP) were evaluated in relation to continuously monitored atrial pressures in a pacing model of heart failure. Pigs were subjected to rapid atrial pacing (225 beats min,1) for 3 weeks with adjustments of pacing frequencies if the pigs showed overt signs of cardiac decompensation. Atrial pressures were monitored by a telemetry system with the animals unsedated and freely moving. Left atrial pressure responded stronger and more rapidly to the initiation of pacing and to alterations in the rate of pacing than right atrial pressure. Plasma natriuretic peptide levels were measured by radioimmunoassay and all increased during pacing with BNP exhibiting the largest relative increase (2.9-fold increase relative to sham pigs). Multiple regression analysis with dummy variables was used to evaluate the relative changes in natriuretic peptides and atrial pressures and the strongest correlation was found between BNP and left atrial pressure with R,2=0.81. Termination of pacing resulted in rapid normalization of ANP values in spite of persistent elevations in atrial pressures. This may reflect an increased metabolism or an attenuated secretory response of ANP to atrial stretch with established heart failure. In conclusion, 3 weeks of rapid pacing induced significant increases in atrial pressures and natriuretic peptide levels. All the natriuretic peptides correlated with atrial pressures with BNP appearing as a more sensitive marker of cardiac filling pressures than ANP and N-terminal proatrial natriuretic peptide. [source] The Influence of Doping Levels and Surface Termination on the Electrochemistry of Polycrystalline DiamondELECTROANALYSIS, Issue 6 2004Matthew Abstract The influence of surface chemistry and boron doping density on the redox chemistry of Fe(CN) at CVD polycrystalline diamond electrodes is considered. It is demonstrated that for this couple both the doping density and the surface chemistry are important in determining the rate of charge transfer at the electrode/electrolyte interface. For hydrogen terminated CVD diamond metallic electrochemical behavior is always observed, even at boron doping densities as low as 7×1018,cm,3. In contrast, the electrochemical behavior of oxygen terminated CVD diamond varies with doping density, a metallic response being observed at high doping density and semiconductor behavior at low doping density. It is shown that the results attained may be explained by a surface state mediated charge transfer mechanism, thus demonstrating the importance of controlling surface chemistry in electroanalytical applications of diamond. [source] O -Acylated 2-Phosphanylphenol Derivatives , Useful Ligands in the Nickel-Catalyzed Polymerization of EthyleneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2009Dmitry G. Yakhvarov Abstract The title ligands were prepared by O -acylation of 2-diphenylphosphanyl-4-methylphenol (1) or directly by double lithiation of 2-bromo-4-methylphenol and stepwise coupling with ClPPh2 and ClP(O)Ph2 or RC(O)Cl (R = Me, tBu, Ph, 4-MeOC6H4) to afford diphenylphosphinate 2 and carboxylic esters 3a,d. X-ray crystal structure analyses of 3b,d show conformations in which the P -phenyl substituents are rotated away from the ester group and the C(O)O , planes are nearly perpendicular to the phenol ring , plane. O -Acylated phosphanylphenols 2 and 3a,d form highly active catalysts with Ni(1,5-cod)2 (as does 1) for polymerization of ethylene, whereas phosphanylphenyl ethers do not give catalysts under the same conditions. The reason is the cleavage of the O -acyl bond upon heating with nickel(0) precursor compounds in the presence of ethylene. The precursors are P-coordinated Ni0 complexes, which are formed at room temperature, such as 4d obtained from 3d and Ni(cod)2 (in a 2:1 molar ratio), and characterized by multinuclear NMR spectroscopy. Upon heating in the presence of ethylene, the precatalysts are activated. Catalysts 2Ni and 3a,dNi convert ethylene nearly quantitatively, 2Ni slowly, and 3a,dNi rapidly, into linear polyethylene with vinyl and methyl end groups, and in the latter case, C(O)R end groups are also detectable. This proves insertion of Ni0 into the O,C(O)R bond of 3a,d ligands for formation of the primary catalyst. Termination of the first chain growing cycle by ,-hydride elimination changes the mechanism to the phosphanylphenolate,NiH initiated polymerization providing the main body of the polymer. A small retardation in the ethylene consumption rate with 3a,dNi catalysts relative to that observed for 1Ni and stabilization of the catalyst, which gives rise to reproducibly high ethylene conversion, is observed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Transcription termination and anti-termination in E. coliGENES TO CELLS, Issue 8 2002Evgeny Nudler Transcription termination in Escherichia coli is controlled by many factors. The sequence of the DNA template, the structure of the transcript, and the actions of auxiliary proteins all play a role in determining the efficiency of the process. Termination is regulated and can be enhanced or suppressed by host and phage proteins. This complex reaction is rapidly yielding to biochemical and structural analysis of the interacting factors. Below we review and attempt to unify into basic principles the remarkable recent progress in understanding transcription termination and anti-termination. [source] Internal Nucleophilic Termination in Acid-Mediated Polyene Cyclizations Part 4,HELVETICA CHIMICA ACTA, Issue 12 2005Synthetic Access to Tetracyclic Didehydro, Tetradehydro Analogues of (±)- Ambrox® Treatment of the unsaturated bicyclic homoallylic alcohols (E)- and (Z)- 5 and (Z)- and (E)- 10 and allenic alcohol 16 with an excess of ClSO3H in 2-nitropropane or CH2Cl2 at ,,80° afforded, in moderate yields (ca. 30,70%), diastereoisomer mixtures of racemic tetracyclic ethers 12a,c (Table,1) and 17a,b (Table,2), respectively. These kinetically controlled stereospecific transformations are believed to proceed via concerted or nonconcerted pathways (see Schemes,4 and 6) and the results are fully consistent with our earlier work. Representing novel didehydro bridged analogues of known, olfactively active labdane tricyclic ethers, the organoleptic properties of 12a,c and 17a,b are briefly described, especially those of 12c which, in the context of structure,activity studies, is a racemic didehydro analogue of the known ambergris odorant Ambrox®. [source] Termination as a therapeutic intervention when treating children who have experienced multiple lossesINFANT MENTAL HEALTH JOURNAL, Issue 1 2009Michele M. Many Children who have endured traumatizing events often have a history of prior disruptions and losses which also have been experienced as traumatic. Termination of therapy with these children, therefore, provides a unique opportunity for the clinician to provide the traumatized child and his or her caregiver with a new experience of loss; one that is controlled, predictable, and paced. Through this experience, the child and caregiver can develop a new model for loss, one that permits for losses that are a natural part of healthy growth and change. This article outlines one approach to utilizing termination as an integral component of the therapeutic process with infants, toddlers, and preschoolers and their caregivers. Using a psychodynamic model and working dyadically with the child and the caregiver, termination is approached as a primary intervention, pivotal to the successful treatment of this vulnerable population. [source] Norms, Activists, and Legislative Pressure in Strategic Commitment TerminationINTERNATIONAL STUDIES REVIEW, Issue 3 2009Andrew Flibbert No abstract is available for this article. [source] Amiodarone or Procainamide for the Termination of Sustained Stable Ventricular Tachycardia: An Historical Multicenter ComparisonACADEMIC EMERGENCY MEDICINE, Issue 3 2010Keith A. Marill MD Abstract Objectives:, The objective was to compare the effectiveness of intravenous (IV) procainamide and amiodarone for the termination of spontaneous stable sustained ventricular tachycardia (VT). Methods:, A historical cohort study of consecutive adult patients with stable sustained VT treated with IV amiodarone or procainamide was performed at four urban hospitals. Patients were identified for enrollment by admissions for VT and treatment with the study agents in the emergency department (ED) from 1993 to 2008. The primary measured outcome was VT termination within 20 minutes of onset of study medicine infusion. A secondary effectiveness outcome was the ultimate need for electrical therapy to terminate the VT episode. Major adverse effects were tabulated, and blood pressure responses to medication infusions were compared. Results:, There were 97 infusions of amiodarone or procainamide in 90 patients with VT, but the primary outcome was unknown after 14 infusions due to administration of another antidysrhythmic during the 20-minute observation period. The rates of VT termination were 25% (13/53) and 30% (9/30) for amiodarone and procainamide, respectively. The adjusted odds of termination with procainamide compared to amiodarone was 1.2 (95% confidence interval [CI] = 0.4 to 3.9). Ultimately, 35/66 amiodarone patients (53%, 95% CI = 40 to 65%) and 13/31 procainamide patients (42%, 95% CI = 25 to 61%) required electrical therapy for VT termination. Hypotension led to cessation of medicine infusion or immediate direct current cardioversion (DCCV) in 4/66 (6%, 95% CI = 2 to 15%) and 6/31 (19%, 95% CI = 7 to 37%) patients who received amiodarone and procainamide, respectively. Conclusions:, Procainamide was not more effective than amiodarone for the termination of sustained VT, but the ability to detect a significant difference was limited by the study design and potential confounding. As used in practice, both agents were relatively ineffective and associated with clinically important proportions of patients with decreased blood pressure. ACADEMIC EMERGENCY MEDICINE 2010; 17:297,306 © 2010 by the Society for Academic Emergency Medicine [source] Simultaneous Atrial and Ventricular Anti-Tachycardia Pacing as a Novel Method of Rhythm DiscriminationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2006SAMIR SABA M.D. Background: Inappropriate shocks remain a problem in patients with defibrillators (ICD). Objective: To evaluate a new discrimination algorithm for supraventricular (SVT) and ventricular (VT) tachycardias, based on the response to simultaneous (A+V) atrial (A) and ventricular (V) anti-tachycardia pacing (ATP). Methods: Patients undergoing electrophysiological testing or dual-chamber implantable cardioverter-defibrillator (ICD) implantation were enrolled (N = 32) and underwent A+V ATP through a Marquis ICD with investigational software. If persisting after ATP, the rhythm was classified as VT if the first electrical event was sensed on the V channel and as an SVT otherwise. Results: Arrhythmia sequences (N = 275; 53 VT; 222 SVT) were analyzed in 26 patients (age = 51 ± 17 years, 13 men, LVEF = 0.49 ± 0.14). In response to A+V ATP, 55% of SVT versus 41% of VT episodes were terminated (P = NS). Termination of VT but not of SVT was more likely with faster (50% at ATP/arrhythmia cycle length (CL) = 0.81 vs 8% at ATP/arrhythmia CL = 0.88, P = 0.02) but not with longer ATP bursts (P = NS). Of the 115 arrhythmias that persisted after A+V ATP, the algorithm correctly classified 24 of 24 VT (GEE-adjusted sensitivity = 100%) and 85 of 91 SVT (GEE-adjusted specificity = 93%). Proarrhythmia was noted after two A+V ATP, in the form of atrial fibrillation induction and VT acceleration. Conclusions: We describe a new algorithm that can discriminate between SVT and VT with a high sensitivity and specificity. This form of ATP can terminate 55% of SVT sequences. The performance of this new algorithm merits further testing in a large population of dual-chamber ICD patients. [source] Catheter Ablation of Long-Lasting Persistent Atrial Fibrillation: Critical Structures for TerminationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2005MICHEL HAÏSSAGUERRE M.D. Background: The relative contributions of different atrial regions to the maintenance of persistent atrial fibrillation (AF) are not known. Methods: Sixty patients (53 ± 9 years) undergoing catheter ablation of persistent AF (17 ± 27 months) were studied. Ablation was performed in a randomized sequence at different left atrial (LA) regions and comprised isolation of the pulmonary veins (PV), isolation of other thoracic veins, and atrial tissue ablation targeting all regions with rapid or heterogeneous activation or guided by activation mapping. Finally, linear ablation at the roof and mitral isthmus was performed if sinus rhythm was not restored after addressing the above-mentioned areas. The impact of ablation was evaluated by the effect on the fibrillatory cycle length in the coronary sinus and appendages at each step. Activation mapping and entrainment maneuvers were used to define the mechanisms and locations of intermediate focal or macroreentrant atrial tachycardias. Results: AF terminated in 52 patients (87%), directly to sinus rhythm in 7 or via the ablation of 1,6 intermediate atrial tachycardias (total 87) in 45 patients. This conversion was preceded by prolongation of fibrillatory cycle length by 39 ± 9 msec, with the greatest magnitude occurring during ablation at the anterior LA, coronary sinus and PV-LA junction. Thirty-eight atrial tachycardias were focal (originating dominantly from these same sites), while 49 were macroreentrant (involving the mitral or cavotricuspid isthmus or LA roof). Patients without AF termination displayed shorter fibrillatory cycles at baseline: 130 ± 14 vs 156 ± 23 msec; P = 0.002. Conclusion: Termination of persistent AF can be achieved in 87% of patients by catheter ablation. Ablation of the structures annexed to the left atrium,the left atrial appendage, coronary sinus, and PVs,have the greatest impact on the prolongation of AF cycle length, the conversion of AF to atrial tachycardia, and the termination of focal atrial tachycardias. [source] Termination of Epicardial Left Ventricular Tachycardia by Pacing without Global CaptureJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2005ASEEM D. DESAI M.D. It is generally accepted that the diagnosis of an epicardial origin of ventricular tachycardia (VT) can be made indirectly by observing VT termination during ablation on the epicardial surface of the heart. There is a caveat, however, which is that termination of VT during radiofrequency current application on the epicardial surface could be due to extension of the lesion beyond the epicardium. Therefore, successful ablation of VT using an epicardial approach does not necessarily prove the reentrant circuit is located superficially. We present a case of a 44-year-old man with VT storm who demonstrated successful termination of VT with radiofrequency current application on the epicardial surface of the heart. This site corresponded to a site where pacing during VT resulted in termination of VT without global capture. Isolated mid-diastolic potentials were only seen at this site as well. We hypothesize that the finding of termination of VT by pacing without global capture supports the argument that the site of pacing is a critical part of the VT circuit. [source] Unusual Mode of Tachycardia Termination Uncovers the Underlying Arrhythmia MechanismJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2004MÁXIMO RIVERO-AYERZA M.D. We discuss the differential diagnosis of a tachycardia with a broad QRS complex and how the mode of termination helped elucidate the underlying tachycardia mechanism. [source] Interactions Between Extracellular Stimuli and Excitation Waves in an Atrial Reentrant LoopJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2003CHAD R. JOHNSON B.S.E. Introduction: The interactions between extracellular stimuli and excitation waves propagating in a reentrant loop are a complex function of stimulus parameters, structural properties, membrane state, and timing. Here the goal was a comprehensive understanding of the mechanisms and frequencies of the major interactions between the advancing excitation wave and a single extracellular stimulus, separated from issues of anatomic or geometric complexity. Methods and Results: A modernized computer model of a thin ring of uniform tissue that included a pair of extracellular stimulus electrodes (anode/cathode) was used to model one-dimensional cardiac reentry. Questions and results included the following: (1) What are the major interactions between a stimulus and the reentrant propagation wave, and are they induced near the cathode or near the anode; and, for each interaction, what are the initiating amplitude range and timing interval? At the cathode, the well-known mechanism of retrograde excitation terminated reentry; changes in timing or amplitude produced double-wave reentry or phase reset. At the anode, termination occurred at different cells depending on stimulus amplitude. (2) Relatively how often did termination occur at the anode? For most stimulus amplitudes, termination occurred more often at the anode than at the cathode, although not always at the same cell. (3) With random timing, what is the probability of terminating reentry? Stimulation for 5 msec terminated reentry with a probability from 0% to approximately 10%, as a function of increasing stimulus amplitude. Conclusion: A single extracellular stimulus can initiate major changes in reentrant excitation via multiple mechanisms, even in a simple geometry. Termination of reentry, phase shifts, or double-wave reentry each occurs over well-defined ranges of stimulus amplitude and timing. (J Cardiovasc Electrophysiol, Vol. 14, pp. ***-***, October 2003) [source] Role of Autonomic Tone in the Initiation and Termination of Paroxysmal Atrial Fibrillation in Patients Without Structural Heart DiseaseJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2003Takeshi Tomita M.D. Introduction: Previous studies have suggested that paroxysmal atrial fibrillation (PAF) of vagal origin often occurs at night and PAF of sympathetic origin occurs during the daytime; however, autonomic tone after spontaneous termination of PAF has not been determined. The aim of this study was to evaluate by heart rate variability (HRV) analysis the relationship between the time of PAF onset and autonomic tone before and after PAF. Methods and Results: Twenty-three patients (65 ± 2years) who underwent 24-hour ambulatory monitoring, had one or more episodes of PAF (>30 min), and had maintained normal sinus rhythm for >60 min before/after PAF were enrolled in this study. Mean duration of PAF was6.2 ± 1.2hours. HRV parameters were analyzed in a 10-minutes section at 60 minutes, 20 minutes, and immediately before the onset of PAF and after its termination. PAF began at night in 14 patients (group N) and during the daytime in 9 patients (group D). In group N, the high-frequency (HF) component and low-frequency (LF) component showed a significant decrease after PAF; PAF was preceded by a gradual increase in HF and LF. Changes in the LF/HF ratio, however, did not occur before or after PAF. Conversely, group D showed a significant increase in the LF/HF ratio before PAF and a decrease in LF and the LF/HF ratio after PAF, but no changes in HF. These changes in HRV parameters were not influenced by the duration or termination time of PAF. Conclusion: This study suggests that the autonomic nervous system plays an important role in both the initiation and termination of PAF. Furthermore, the time of PAF onset influences the autonomic tone at the initiation and termination of PAF. (J Cardiovasc Electrophysiol, Vol. 14, pp. 559-564, June 2003) [source] Supervulnerable Phase Immediately After Termination of Atrial FibrillationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2002MATTIAS DUYTSCHAEVER M.D. Supervulnerable Phase After Termination of AF.Introduction: Recent studies with the implantable atrial cardioverter have shown that atrial fibrillation (AF) recurs almost immediately after successful cardioversion in about 27% of cases. In the present study, we determined the electrophysiologic properties of the caprine atrium immediately after spontaneous termination of AF both before and after 48 hours of AF-induced electrical remodeling. Methods and Results: In eight goats, atrial effective refractory period (AERP), intra-atrial conduction velocity, and atrial wavelength were measured during sinus rhythm both before (t = 0) and after 48 hours (t = 48) of electrically maintained AF (baseline). After baseline, a 5-minute paroxysm of AF was induced, during which the refractory period (RPAF) was determined. AERP, conduction velocity, and atrial wavelength also were measured immediately after spontaneous restoration of sinus rhythm (post-AF values). Both in normal and remodeled atria, immediately after AF, AERP and conduction velocity were markedly decreased compared with baseline (P < 0.01). In normal atria, post-AF AERP (107 ± 14 msec) gradually prolonged from its AF value (114 ± 17 msec) to its baseline value (138 ± 13 msec). Conduction velocity decreased from 130 ± 9 cm/sec to 117 ± 9 cm/sec. After 48 hours of AF, AERP had shortened to 74 ± 8 msec. RPAF was 89 ± 9 msec. Surprisingly, immediately after termination of AF, AERP shortened further to 58 ± 6 msec (P < 0.01). Post-AF conduction velocity decreased from 136 ± 11 cm/sec to 122 ± 10 cm/sec (P < 0.01). As a result, the post-AF atrial wavelength became as short as 7.1 ± 1 cm. These changes were transient, and all parameters gradually returned to baseline within 1 to 2 minutes after conversion of AF. Conclusion: Due to a combined decrease in AERP and conduction velocity, marked shortening of the atrial wavelength occurs during the first minutes after conversion of AF. In electrically remodeled atria, this results in a transient ultrashort value of AERP (< 60 msec) and atrial wavelength (7.1 cm). These observations imply a highly vulnerable substrate for reentry immediately after termination of AF. During this supervulnerable phase, both early and later premature beats reinitiated immediate recurrences of AF. [source] Virological and immunological features of active cytomegalovirus infection in nonimmunosuppressed patients in a surgical and trauma intensive care unit,JOURNAL OF MEDICAL VIROLOGY, Issue 8 2010Marifina Chilet Abstract Cytomegalovirus (CMV) reactivation occurs frequently in critically ill patients. The natural course of CMV infection and the interaction between CMV and the adaptive immune system in this setting remain poorly defined. Fifty-three CMV-seropositive patients in a surgical and trauma intensive care unit were included in this study. The CMV DNA load in tracheal aspirates (TA) and plasma (PL) was monitored by qPCR. CMV-specific T-cell immunity was assessed by intracellular cytokine staining. Plasma TNF-, levels were determined by ELISA. CMV reactivation occurred in 39.7% of patients (23% had CMV DNA detected only in TA). The analysis of TA allowed an earlier diagnosis in 28% of patients. Clearance of CMV DNAemia preceded that of CMV DNA in TA in some episodes. Peak CMV DNA levels were significantly higher in TA than in PL (P,=,0.02). CMV reactivation developed in the presence of CMV-specific T cells. Termination of CMV reactivation was associated with an expansion of functional CMV-specific T cells. Plasma levels of TNF-, did not allow for the prediction of the occurrence of CMV reactivation. CMV-specific T-cell immunity is preserved in most critically ill patients experiencing CMV reactivation. Analysis of respiratory specimens is imperative for an optimal monitoring of CMV reactivation in this setting. J. Med. Virol. 82:1384,1391, 2010. © 2010 Wiley-Liss, Inc. [source] Midtrimester termination of pregnancy using gemeprost in combination with laminaria in women who have previously undergone cesarean sectionJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 5 2009Mana Obata-Yasuoka Abstract Aim:, We aimed to assess the efficacy and safety of midtrimester termination of pregnancy using gemeprost in combination with laminaria in women who had previously undergone cesarean section and in women who had not. Methods:, Between January 1999 and December 2006, we carried out a retrospective study of termination of pregnancy at 12,21 weeks of gestation at the University of Tsukuba Hospital. Termination of pregnancy was carried out by three-step uterine cervical dilation using laminaria followed by vaginal administration of 1 mg gemeprost every 3 h for up to four doses over 24 h. Results:, A total of 173 women underwent midtrimester termination of pregnancy. The women were categorized into two groups: those who had previously undergone cesarean section (n = 26) (previous cesarean section group) and those who had not (n = 147) (control group). Seven women had undergone cesarean section at least twice. The gemeprost dose administered was 2.8 ± 1.4 mg for the previous cesarean section group and 2.4 ± 1.6 mg for the control group (difference in doses not significant). Although abnormal vaginal bleeding (>500 mL) was more likely to occur in the previous cesarean section group than in the control group (odds ratio, 2.61; 95% confidence interval, 0.63,10.82), none of the woman required blood transfusion. Uterine rupture and failed abortion were not observed. Conclusion:, The efficacy and safety of our laminaria-gemeprost protocol for termination of pregnancy during the midtrimester are similar for women who have previously undergone cesarean section and those who have not. [source] Abrupt Termination of an Ethanol Regimen Provokes Ventricular Arrhythmia and Enhances Susceptibility to the Arrhythmogenic Effects of Epinephrine in RatsALCOHOLISM, Issue 2010Jinyao Liu Background:, Pathologists examining victims of sudden unexpected death encounter alcoholics more often than expected; alcohol may play a role in sudden arrhythmic death. Here we determine whether a pattern of alcohol consumption, chronic ethanol intake, and withdrawal increases the incidence of malignant ventricular arrhythmia and modulates susceptibility to the arrhythmogenic potential of sympathetic stimulation from an epinephrine test in rats. Methods:, Male Wistar rats were treated with a continuous ethanol liquid diet for 7 weeks, and then subjected to 1-day withdrawal or 21-day abstinence. Ventricular ectopy was evaluated by 24-hour electrocardiographic telemetry recording; whole-body sympathetic activation, cardiac sympathovagal balance, and susceptibility to ventricular arrhythmia induced by sympathetic stimulation were evaluated based on blood noradrenalin metabolite concentrations, heart rate variability, and a 3-step epinephrine test. Results:, Ventricular arrhythmia and related death were observed only in rats at 1 day of withdrawal, but not in nonalcoholic, continuous ethanol intake or 21-day abstinence rats. One-day withdrawal after a 7-week continuous ethanol regimen elevated circulating noradrenalin metabolite levels and induced cardiac sympathovagal imbalance. Deaths related to the epinephrine test and ventricular arrhythmia induced by low doses of epinephrine were observed only in 1-day withdrawal rats. However, all anomalies were normalized by 21-day abstinence. Conclusions:, Abrupt termination of a 7-week continuous ethanol regimen is sufficient to enhance the whole-body sympathetic activation and cardiac sympathovagal imbalance that contribute to ventricular arrhythmia and sudden death in alcoholic rats. Those providing medical care for alcoholics, including in cases of legal imprisonment, should be aware of the possibility of enhanced susceptibility to sudden arrhythmic death due to the abrupt termination of a chronic ethanol regimen. [source] Holocene bipolar climate seesaw: possible subtle evidence from the deep North East Atlantic Ocean?,JOURNAL OF QUATERNARY SCIENCE, Issue 3 2010Mark A. Maslin Abstract The occurrence of a millennial-scale bipolar climate seesaw has been documented in detail for the last glacial period and Termination. There is, however, debate whether it occurs during interglacials and if it does what influence it could have on future climate. We present here new evidence from a North East Atlantic Ocean deep-sea core which supports the hypothesis for a Holocene bipolar climate seesaw. BENGAL Site 13078#16, from the Porcupine Abyssal Plain, is 4844,m deep and situated at the North Atlantic Deep Water and Antarctic Bottom Water (AABW) interface. Planktic foraminiferal fragment accumulation rate data at this site is an indicator of coarse carbonate dissolution, which is highly sensitive to the incursion of under-saturated AABW. Five dissolution peaks have been identified, which seem to occur approximately 500 a after each of the North Atlantic 'Bond' ice rafting pulses, suggesting a subsequent subtle shallowing of AABW. This indicates a possible lagged climatic link between North East Atlantic surface water conditions and AABW production in the Southern Ocean during the Holocene. This provides the first tentative evidence that there was a Holocene bipolar climate seesaw and that the deep ocean was involved. This study also suggests that extremely sensitive locations need to be sought as the Holocene bipolar climate seesaw seems to be very subtle compared with its glacial counterparts. Copyright © 2009 John Wiley & Sons, Ltd. [source] Climatic oscillations in central Italy during the Last Glacial,Holocene transition: the record from Lake Accesa,JOURNAL OF QUATERNARY SCIENCE, Issue 4 2006Michel Magny Abstract This paper presents an event stratigraphy based on data documenting the history of vegetation cover, lake-level changes and fire frequency, as well as volcanic eruptions, over the Last Glacial,early Holocene transition from a terrestrial sediment sequence recovered at Lake Accesa in Tuscany (north-central Italy). On the basis of an age,depth model inferred from 13 radiocarbon dates and six tephra horizons, the Oldest Dryas,Bølling warming event was dated to ca. 14,560,cal.,yr,BP and the Younger Dryas event to ca. 12,700,11,650,cal.,yr,BP. Four sub-millennial scale cooling phases were recognised from pollen data at ca. 14,300,14,200, 13,900,13,700, 13,400,13,100 and 11,350,11,150,cal.,yr,BP. The last three may be Mediterranean equivalents to the Older Dryas (GI-1d), Intra-Allerød (GI-1b) and Preboreal Oscillation (PBO) cooling events defined from the GRIP ice-core and indicate strong climatic linkages between the North Atlantic and Mediterranean areas during the last Termination. The first may correspond to Intra-Bølling cold oscillations registered by various palaeoclimatic records in the North Atlantic region. The lake-level record shows that the sub-millennial scale climatic oscillations which punctuated the last deglaciation were associated in central Italy with different successive patterns of hydrological changes from the Bølling warming to the 8.2,ka cold reversal. Copyright © 2006 John Wiley & Sons, Ltd. [source] Volcanic ash layers from the Last Glacial Termination in the NGRIP ice core,JOURNAL OF QUATERNARY SCIENCE, Issue 3 2005Anette K. Mortensen Abstract The tephrochronological record of the 1400,1640,m depth (,10,000,16,000 calendar ice core years before present) of the NGRIP ice core has been established by particle screening of selected samples. Ash was identified in 20 samples. Correlation with ice, marine and terrestrial records from volcanic source regions in the northern hemisphere positively identifies the Saksunarvatn Ash and the Vedde Ash (Ash Zone 1). Major element chemistry of the remaining identified ash layers mainly points towards an Icelandic origin. This tephrochronological record provides new important marker horizons for correlating the timing of the climatic changes associated with the Last Glacial Termination within the North Atlantic region, as well as outlining more details concerning the frequency and composition of volcanic eruptions occurring at this deglaciation. Copyright © 2005 John Wiley & Sons, Ltd. [source] Tephrochronology of last termination sequences in Europe: a protocol for improved analytical precision and robust correlation procedures (a joint SCOTAV,INTIMATE proposal)JOURNAL OF QUATERNARY SCIENCE, Issue 2 2004Chris S. M. Turney Abstract The precise sequence of events during the Last Termination (18,000,9000,ka 14C,yr BP), and the extent to which major environmental changes were synchronous, are difficult to establish using the radiocarbon method alone because of serious distortions of the radiocarbon time-scale, as well as the influences of site-specific errors that can affect the materials dated. Attention has therefore turned to other methods that can provide independent tests of the chronology and correlation of events during the Last Termination. With emphasis on European sequences, we summarise here the potential of tephrostratigraphy and tephrochronology to fulfil this role. Recent advances in the detection and analysis of ,hidden' tephra layers (cryptotephra) indicate that some tephras of Last Termination age are much more widespread in Europe than appreciated hitherto, and a number of new tephra deposits have also been identified. There is much potential for developing an integrated tephrochronological framework for Europe, which can help to underpin the overall chronology of events during the Last Termination. For that potential to be realised, however, there needs to be a more systematic and robust analysis of tephra layers than has been the practice in the past. We propose a protocol for improving analytical and reporting procedures, as well as the establishment of a centralised data base of the results, which will provide an important geochronological tool to support a diverse range of stratigraphical studies, including opportunities to reassess volcanic hazards. Although aimed primarily at Europe, the protocol proposed here is of equal relevance to other regions and periods of interest. Copyright © 2004 John Wiley & Sons, Ltd. [source] A Mathematical Model for Photopolymerization From a Stationary Laser Light SourceMACROMOLECULAR THEORY AND SIMULATIONS, Issue 1 2005Michael F. Perry Abstract Summary: A mathematical model of photopolymerization is presented for a stationary laser. Termination by radical combination and radical trapping is considered. Using simplifying assumptions, we derive analytical equations for the concentration of photoinitiator and monomer in the system. With these equations, we show that the light intensity and the initial amount of photoinitiator highly influence the polymerization process and determine the shape of the polymer that is formed. We also provide an analytic expression to determine the amount of polymer formed during dark reactions. Percent conversion of monomer as a function of time at z,=,0 and r,=,0 (Data from Table 1). [source] Termination in Dilute-Solution Free-Radical Polymerization: A Composite ModelMACROMOLECULAR THEORY AND SIMULATIONS, Issue 5 2003Gregory B. Smith Abstract Literature data are summarized for the chain-length-dependence of the termination rate coefficient in dilute solution free-radical polymerizations. In essence such experiments have yielded two parameter values: the rate coefficient for termination between monomeric free radicals, k, and a power-law exponent e quantifying how kt values decrease with increasing chain length. All indications are that the value e,,,0.16 in good solvent is accurate, however the values of k which have been deduced are considerably lower than well-established values for small molecule radicals. This seeming impasse is resolved by putting forward a ,composite' model of termination: it is proposed that the value e,,,0.16 holds only for long chains, with e being higher for small chains , the value 0.5 is used in this paper, although it is not held to dogmatically. It is then investigated whether this model is consistent with experimental data. This is a non-trivial task, because although the experiments themselves and the ways in which they are analyzed are elegant and not too complicated, the underlying theory is sophisticated, as is outlined. Simulations of steady-state polymerization experiments are first of all carried out, and it is shown that the composite model of termination both recovers the e values which have been found and beautifully explains why these experiments considerably underestimate the true value of k. Simulations of pulsed-laser polymerizations find the same, although not quite so strikingly. It is therefore concluded that our new termination model, which retains the virtue of simplicity and in which all parameter values are physically reasonable, is consistent with experimental data. Taking a wider view, it seems likely that the situation of the exponent e varying with chain length will not just be the case in dilute solution, but will be the norm for all conditions, which would give our model and our work a general relevance. Normalized chain length distributions from PLP simulations. [source] Emerging views on tmRNA-mediated protein tagging and ribosome rescueMOLECULAR MICROBIOLOGY, Issue 4 2001Reynald Gillet Transfer- messenger RNA (tmRNA), also known as SsrA or 10Sa RNA, is a bacterial ribonucleic acid that recycles 70S ribosomes stalled on problematic messenger RNAs (mRNAs) and also contributes to the degradation of incompletely synthesized peptides. tmRNA acts initially as transfer RNA (tRNA), being aminoacylated at its 3,-end by alanyl-tRNA synthetase, to add alanine to the stalled polypeptide chain. Resumption of translation ensues not on the mRNA on which the ribosomes were stalled but at an internal position in tmRNA. Termination soon occurs, tmRNA recruiting the appropriate termination factors allowing the release of the tagged protein that is subsequently recognized and degraded by specific cytoplasmic and periplasmic proteases, and permits ribosome recycling. Recent data suggest that tmRNA tags bacterial proteins in three other instances; when ribosomes stall at internal sites; during ,readthrough' of canonical termination codons; and when ribosomes are at the termination codon of intact messages. The importance of bacterial tmRNAs for survival, growth under stress, and pathogenesis is also discussed. Recent in vivo and in vitro studies have identified novel ligands of tmRNA. Based on the available experimental evidences, an updated model of tmRNA mediated protein tagging and ribosome rescue in bacteria is presented. [source] Patient Care Through Pregnancy TerminationNURSING FOR WOMENS HEALTH, Issue 4 2003Mary Beth Haire RN No abstract is available for this article. [source] Implantable Cardioverter-Defibrillator Discharges Despite Successful Termination of Ventricular Tachycardia by Antitachycardia PacingPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2009REGINALD T. HO M.D. No abstract is available for this article. [source] Prolonged Asystole after Termination of Atrial Arrhythmias:PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2007Not So Uncommon? No abstract is available for this article. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||