bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epidemiology of Posttraumatic Epilepsy: A Critical Review
Authors: Frey Lauren C. 
Published: December 2004

Summary:  Problem: Traumatic brain injury (TBI) is a major cause of epilepsy. We need to understand its frequency and its contribution to the total spectrum of the convulsive disorders. Methods: A review of selected articles dealing with epilepsy after brain trauma was undertaken. Results: The number of epidemiologic studies of posttraumatic seizures has increased substantially over the past 40–50 years, offering steadily increasing knowledge of the frequency, natural history, and risk factors of this well‐recognized complication of TBI. In general, the incidence of posttraumatic seizures varies with the time period after injury and population age range under study, as well as the spectrum of severity of the inciting injuries, and has been reported to be anywhere from 4 to 53%. As high as 86% of patients with one seizure after TBI will have a second in the next 2 years. Longer‐term remission rates of 25–40% have been reported. Significant risk factors for the development of seizures in the first week after injury include acute intracerebral hematoma (especially subdural hematoma), younger age, increased injury severity, and chronic alcoholism. Significant risk factors for the development of seizures >1 week after TBI include seizures within the first week, acute intra‐cerebral hematoma (especially subdural hematoma), brain contusion, increased injury severity, and age >65 years at the time of injury. Conclusions: Epilepsy is a frequent consequence of brain injury in both civilian and military populations. We understand some factors associated with its development, but there remain many unanswered questions.
Biophysics of Ablation:
Authors: HAINES DAVID 
Published: December 2004

Introduction: The question of what happens to tissue during radiofrequency (RF) catheter ablation continues to be asked as we evolve into the use of newer delivery systems. Methods and Results: Three assumptions are made about RF ablation. (1) Tissue injury is thermally mediated; (2) heat transfer in tissue should be a predictable biophysical phenomenon; and (3) large lesion technologies have more or less equivalent efficacies. Based on these assumptions, predictions are made and discussed. Many of the predictors were proven to be true while some surprisingly were not. Conclusion: In conclusion, tissue‐area injury occurs reproducibly at a temperature of about 50°C. Heat transfer in tissue is a predictable phenomenon. And finally, new technologies for large lesions are all effective, but greater surface area of ablation was achieved with a 10‐mm tip and greater depth was achieved with a Chilli® cooled ablation catheter.
Experimental Study of Compressional Hydromagnetic Waves
Authors: Swanson D. G. , Gould R. W. , Hertel R. H. 
Published: December 2004

An experiment is described in which a compressional hydromagnetic wave is observed in a hydrogen plasma-filled waveguide. The theory of a cool, partially ionized, resistive plasma in a magnetic field is described briefly and expressions are derived for the dispersion relation and transfer function which include both the propagation and attenuation constants as a function of frequency. Measurements of the cutoff frequency are presented, which verify its linear dependence on the magnetic field, and they show good agreement with theory on the variation with the ion mass density. The impulse response of the plasma is studied, transformed into the frequency domain, and quantitative comparisons are made with the theoretical transfer function to determine the degree of ionization, the resistivity, and the ion-neutral collision frequency.
Results indicate that the degree of ionization varies over a range from 75% to 45% when the initial density varies from 1.3 × 1021 to 1.4 × 1022 atoms/m3. The measured resistivity appears to increase with the magnetic field, with the mean value corresponding to a temperature of the order of 5 × 103 °K. The average value of the product of the charge exchange cross section and the neutral thermal speed is found to be approximately (5.5 ± 1.3) × 10−15 m3/sec.
Theoretical Structure of Plasma Equations
Authors: Rosenbluth M. N. , Rostoker N. 
Published: December 2004

In high-temperature plasmas, collisions are very infrequent. Thus the charged particles travel on independent orbits determined by the electromagnetic field. At first sight this would seem completely different from a conventional fluid where particles are closely hemmed in by their neighbors. However, there can exist collective modes of motion in which the particles interact with each other by altering the fields.
In this paper a new method is developed for the solution of the linearized transport equation. By facilitating direct use of the properties of particle orbits, a considerable simplification is achieved. In particular, a variational expression is derived for determining stability which is rigorous in the limit of small Larmor radius.
Terlipressin versus Norepinephrine to Counteract Anesthesia-induced Hypotension in Patients Treated with Renin-Angiotensin System Inhibitors: Effects on Systemic and Regional Hemodynamics
Authors: Morelli Andrea , Tritapepe Luigi , Rocco Monica , Conti Giorgio , Orecchioni Alessandra , De Gaetano Andrea , Picchini Umberto , Pelaia Paolo , Reale Carlo , Pietropaoli Paolo 
Published: December 2004

Background
Terlipressin has been suggested as the ideal drug to treat anesthesia-induced hypotension in patients under long-term renin-angiotensin system inhibitor treatment for arterial hypertension. The authors compared the effects of terlipressin and norepinephrine on systemic hemodynamic parameters and gastric mucosal perfusion using a laser Doppler flowmetry technique in patients treated with renin-angiotensin system inhibitors who experienced hypotension at induction of anesthesia.

Methods
Thirty-two patients scheduled for carotid endarterectomy under general anesthesia and treated with renin-angiotensin system inhibitors had hypotension after induction of general anesthesia. They were randomized to receive 1 mg of terlipressin (n = 16) or norepinephrine infusion (n = 16) to counteract anesthesia-induced hypotension. A laser Doppler probe was introduced into the gastric lumen. All measurements were performed just before surgery, during hypotension, at 30 min, and at 4 h.

Results
Terlipressin produced an increase in mean arterial pressure and a decrease in gastric mucosal perfusion detected by laser Doppler flowmetry (P < 0.05) over 30 min that were sustained for 4 h. During the infusion, norepinephrine produced an increase in mean arterial pressure and in gastric mucosal perfusion detected by laser Doppler flowmetry (P < 0.05). If compared to norepinephrine, terlipressin reduced oxygen delivery and oxygen consumption (P < 0.05) and increased arterial lactate concentrations (P < 0.05).

Conclusion
This study showed the efficacy of terlipressin in the treatment of hypotension episodes in anesthetized patients chronically treated with renin-angiotensin system inhibitors, angiotensin converting-enzyme inhibitors, and angiotensin II receptor antagonists. However, the negative effects on gastric mucosal perfusion and the risk of iatrogenic oxygen supply dependency of terlipressin need to be taken into account.
Laryngeal Reflex before and after Placement of Airway Interventions: Endotracheal Tube and Laryngeal Mask Airway™
Authors: Tanaka Atsuko , Isono Shiroh , Ishikawa Teruhiko , Nishino Takashi 
Published: December 2004

Background
Previous reports indicate that detrimental laryngeal function persists over several hours after tracheal extubation even in patients who have regained full consciousness from anesthesia. The authors hypothesize that even after minor surgery, the presence of an endotracheal tube (ETT) impairs the receptors at the vocal cord and diminishes the defensive laryngeal function. The hypothesis was tested by comparing types of experimentally induced laryngeal airway reflexes before and after surgery in anesthetized patients with use of either an ETT or a Laryngeal Mask Airway.

Methods
Twenty adult patients undergoing elective minor surgeries were randomly allocated into two groups, the ETT and Laryngeal Mask Airway groups, depending on the airway management method used during surgery. While maintaining sevoflurane at 1 minimum alveolar concentration, laryngeal and respiratory responses were elicited by instillation of distilled water on the vocal cords immediately before and after surgery. Furthermore, the vocal cord angles were endoscopically measured under complete paralysis.

Results
Some laryngeal reflex responses of both groups, particularly the cough reflex, were significantly attenuated after minor surgery. Significant narrowing of the glottic aperture was evident in patients with ETT placement but not in patients with Laryngeal Mask Airway placement.

Conclusions
With either airway intervention, laryngeal defensive reflexes are depressed immediately after surgery even without visible laryngeal swelling. The sensory impairment attributable to the presence of an ETT cannot be the solo factor responsible for the modification of the defensive airway reflexes elicited from the larynx.
The Effect of Esmolol on Cerebral Blood Flow, Cerebral Vasoreactivity, and Cognitive Performance: A Functional Magnetic Resonance Imaging Study
Authors: Heinke Wolfgang , Zysset Stefan , Hund-Georgiadis Margret , Olthoff Derk , von Cramon D Yves 
Published: December 2004

Background
Esmolol is often applied perioperatively to maintain stable hemodynamic conditions in neurosurgical patients. Little is known, however, about its effects on cerebral circulation. The authors employed functional magnetic resonance imaging based on blood oxygenation level-dependent contrast to explore the effect of esmolol on the human brain. The purpose of the study was to investigate the effect of esmolol on cerebral blood flow, cerebral vasoreactivity, and cognitive performance.

Methods
Ten healthy volunteers were investigated in two separate experimental sessions using functional magnetic resonance imaging. During the first experimental session, a hyperventilation task and a cognitive task, subjects had to perform both tasks twice, once after administration of an esmolol bolus of 1 mg/kg followed by a continuous infusion of 150 microg.kg.min and once without beta-blockade, in a random order. During the second experimental session subjects were scanned at resting state after administration of esmolol. Furthermore, the effect of the esmolol dose on hemodynamic changes caused by beta-adrenergic stimulation with orciprenaline was investigated.

Results
Esmolol decreased heart rate and blood pressure during the various experimental conditions and blunted the increase in heart rate and blood pressure caused by orciprenaline. Infusion of esmolol affects neither the blood oxygenation level-dependent contrast during the functional challenges nor the reaction times during the cognitive task. However, the esmolol bolus caused a brief blood oxygenation level-dependent contrast increase.

Conclusion
The results indicate that effective beta-blockade with esmolol does not affect cerebral blood flow, cerebrovascular reactivity, or cognitive performance.
Single Acceleromyographic Train-of-Four, 100-Hertz Tetanus or Double-Burst Stimulation: Which Test Performs Better to Detect Residual Paralysis?
Authors: Samet Amir , Capron Florent , Alla François , Meistelman Claude , Fuchs-Buder Thomas 
Published: December 2004

Background
Acceleromyography is regularly used as an isolated test to detect residual paralysis. The performance of acceleromyography, however, has not been investigated for the setting where calibration is impossible. This study first evaluated the reliability of a single acceleromyographic train-of-four (TOF) ratio (T4/T1) to detect residual paralysis and compared it with tactile estimation of fade after double-burst stimulation and 100-Hz, 5-s tetanus. The second part of the study investigated whether uncalibrated acceleromyographic TOF ratio can predict time to complete recovery.

Methods
Anesthesia was induced and maintained with propofol and sufentanil. In the first part of the study (n = 40) neuromuscular blockade was assessed by mechanomyography. After signal stabilization 0.15 mg/kg cisatracurium was given. At the end of surgery a first physician evaluated manual fade after double-burst stimulation, then, in the same patient, a single acceleromyographic TOF ratio was recorded; thereafter a second physician, unaware of the results, assessed fade after a 100-Hz, 5-s tetanus. Sensitivity, specificity, and negative and positive predictive value of the three tests to detect a mechanomyographic TOF > or =0.9 were calculated. In the second part of the study (n = 25) neuromuscular recovery was assessed simultaneously with mechanomyography and uncalibrated acceleromyography (current set manually at 60 mA); the time intervals from acceleromyographic TOF ratios of 0.6, 0.7, 0.8, and 0.9 until complete recovery, i.e., adductor pollicis mechanomyography 0.9 TOF ratios, were determined.

Results
The sensitivity of double burst stimulation was 29% (95% confidence interval [CI], 13-45%), its specificity was 100%, the negative predictive value was 29% (95% CI, 13-45%), and the positive predictive value was 100%. For a single acceleromyographic TOF ratio the respective values were 70% (95% CI, 54-86%), 88% (95% CI, 67-100%), 47% (95% CI, 23-71%) and 95% (95% CI, 86-100%). The respective values for 100-Hz, 5-s tetanus were 74% (95% CI, 59-89%), 55% (95% CI, 23-88%), 38% (95% CI, 12-64%), and 85% (95% CI, 72 -99%). At an uncalibrated acceleromyographic TOF ratio was 0.6, complete recovery occurred within 16 min (95% CI, 13.5-17.8 min). At acceleromyographic TOF ratios of 0.7, 0.8, and 0.9 this time interval was 12.5 min (95% CI, 10.2-14.8 min), 8 min (95% CI, 6.1-9.9 min), and 4 min (95% CI, 2.7-5.8 min), respectively.

Conclusions
Acceleromyographic TOF performed better than double-burst stimulation or 100 Hz tetanus, but it did not reliably detect low degrees of residual paralysis when used as an isolated test at the end of surgery. The uncalibrated acceleromyographic TOF ratio, however, did predict the time to complete recovery.
Comparative Cardiac Effects of Terlipressin, Vasopressin, and Norepinephrine on an Isolated Perfused Rabbit Heart
Authors: Ouattara Alexandre , Landi Marc , Le Manach Yannick , Lecomte Patrick , Leguen Morgan , Boccara Gilles , Coriat Pierre , Riou Bruno 
Published: December 2004

Background
Terlipressin, a synthetic analog of arginine-vasopressin (AVP), has been proposed as an effective vasopressive therapy in catecholamine-resistant vasodilatory shock. Although beneficial effects of terlipressin on systemic arterial pressure have been clearly demonstrated, its intrinsic effects on coronary circulation and myocardial performances remain unknown.

Methods
The authors compared the coronary and myocardial effects of terlipressin (1-100 nM, n = 10), AVP (10-1000 pM, n = 10), and norepinephrine (1-100 nM, n = 10) on an erythrocyte-perfused isolated rabbit heart. The cardiac effects of terlipressin were also assessed in erythrocyte-perfused hearts in which the myocardial oxygen delivery was maintained constant and buffer-perfused hearts. Finally, the cardiac effects of terlipressin and AVP were studied in hearts pretreated by [d(CH2)5Tyr(Me)]AVP (0.1 microM), a selective V1a receptor antagonist.

Results
Norepinephrine induced a biphasic coronary effect associated with a concentration-dependent increase in myocardial performances. AVP and terlipressin significantly decreased coronary blood flow and impaired myocardial performances from 30 pM and 30 nM, respectively (P < 0.05). The cardiac side-effects of terlipressin were confirmed in buffer-perfused hearts but the maintenance of a constant myocardial oxygen delivery constant abolished its effects on myocardial performances. The cardiac effects induced by terlipressin and AVP were nearly completely abolished on hearts pretreated by [d(CH2)5Tyr(Me)]AVP.

Conclusions
On isolated rabbit heart, terlipressin induced a coronary vasopressor effect and in turn myocardial depression only at supratherapeutic concentrations (> or =30 nM). Its effects are mainly mediated via V1a receptors. However, these potential negative side effects on the heart were less pronounced than were those of AVP.
Molecular Mechanisms Underlying Ketamine-mediated Inhibition of Sarcolemmal Adenosine Triphosphate-sensitive Potassium Channels
Authors: Kawano Takashi , Oshita Shuzo , Takahashi Akira , Tsutsumi Yasuo , Tanaka Katsuya , Tomiyama Yoshinobu , Kitahata Hiroshi , Nakaya Yutaka 
Published: December 2004

Background
Ketamine inhibits adenosine triphosphate-sensitive potassium (KATP) channels, which results in the blocking of ischemic preconditioning in the heart and inhibition of vasorelaxation induced by KATP channel openers. In the current study, the authors investigated the molecular mechanisms of ketamine's actions on sarcolemmal KATP channels that are reassociated by expressed subunits, inwardly rectifying potassium channels (Kir6.1 or Kir6.2) and sulfonylurea receptors (SUR1, SUR2A, or SUR2B).

Methods
The authors used inside-out patch clamp configurations to investigate the effects of ketamine on the activities of reassociated Kir6.0/SUR channels containing wild-type, mutant, or chimeric SURs expressed in COS-7 cells.

Results
Ketamine racemate inhibited the activities of the reassociated KATP channels in a SUR subtype-dependent manner: SUR2A/Kir6.2 (IC50 = 83 microM), SUR2B/Kir6.1 (IC50 = 77 microM), SUR2B/Kir6.2 (IC50 = 89 microM), and SUR1/Kir6.2 (IC50 = 1487 microM). S-(+)-ketamine was significantly less potent than ketamine racemate in blocking all types of reassociated KATP channels. The ketamine racemate and S-(+)-ketamine both inhibited channel currents of the truncated isoform of Kir6.2 (Kir6.2DeltaC36) with very low affinity. Application of 100 mum magnesium adenosine diphosphate significantly enhanced the inhibitory potency of ketamine racemate. The last transmembrane domain of SUR2 was essential for the full inhibitory effect of ketamine racemate.

Conclusions
These results suggest that ketamine-induced inhibition of sarcolemmal KATP channels is mediated by the SUR subunit. These inhibitory effects of ketamine exhibit specificity for cardiovascular KATP channels, at least some degree of stereoselectivity, and interaction with intracellular magnesium adenosine diphosphate.
Isoflurane Protects against Myocardial Infarction during Early Reperfusion by Activation of Phosphatidylinositol-3-Kinase Signal Transduction: Evidence for Anesthetic-induced Postconditioning in Rabbits
Authors: Chiari Pascal C. , Bienengraeber Martin W. , Pagel Paul S. , Krolikowski John G. , Kersten Judy R. , Warltier David C. 
Published: December 2004

Background
Brief episodes of ischemia during early reperfusion after coronary occlusion reduce the extent of myocardial infarction. Phosphatidylinositol-3-kinase (PI3K) signaling has been implicated in this "postconditioning" phenomenon. The authors tested the hypothesis that isoflurane produces cardioprotection during early reperfusion after myocardial ischemia by a PI3K-dependent mechanism.

Methods
Pentobarbital-anesthetized rabbits (n = 80) subjected to a 30-min coronary occlusion followed by 3 h reperfusion were assigned to receive saline (control), three cycles of postconditioning ischemia (10 or 20 s each), isoflurane (0.5 or 1.0 minimum alveolar concentration), or the PI3K inhibitor wortmannin (0.6 mg/kg, intravenously) or its vehicle dimethyl sulfoxide. Additional groups of rabbits were exposed to combined postconditioning ischemia (10 s) and 0.5 minimum alveolar concentration isoflurane in the presence and absence of wortmannin. Phosphorylation of Akt, a downstream target of PI3K, was assessed by Western blotting.

Results
Postconditioning ischemia for 20 s, but not 10 s, reduced infarct size (P < 0.05) (triphenyltetrazolium staining; 20 +/- 3% and 34 +/- 3% of the left ventricular area at risk, respectively) as compared with control (41 +/- 2%). Exposure to 1.0, but not 0.5, minimum alveolar concentration isoflurane decreased infarct size (21 +/- 2% and 43 +/- 3%, respectively). Wortmannin abolished the protective effects of postconditioning (20 s) and 1.0 minimum alveolar concentration isoflurane. Combined postconditioning (10 s) and 0.5 minimum alveolar concentration isoflurane markedly reduced infarct size (17 +/- 5%). This action was also abolished by wortmannin (44 +/- 2%). Isoflurane (1.0 minimum alveolar concentration) increased Akt phosphorylation after ischemia (32 +/- 6%), and this action was blocked by wortmannin.

Conclusions
Isoflurane acts during early reperfusion after prolonged ischemia to salvage myocardium from infarction and reduces the threshold of ischemic postconditioning by activating PI3K.
Pulsed and Continous Radiofrequency Current Adjacent to the Cervical Dorsal Root Ganglion of the Rat Induces Late Cellular Activity in the Dorsal Horn
Authors: Van Zundert Jan , de Louw Anton J. A. , Joosten Elbert A. J. , Kessels Alfons G. H. , Honig Wiel , Dederen Pieter J. W. C. , Veening Jan G. , Vles Johan S. H. , van Kleef Maarten 
Published: December 2004

Background
Pulsed radiofrequency treatment has recently been described as a non-neurodestructive or minimally neurodestructive alternative to radiofrequency heat lesions. In clinical practice long-lasting results of pulsed radiofrequency treatment adjacent to the cervical dorsal root ganglion for the management of chronic radicular spinal pain have been reported without neurologic complications. However, the mode of action is unclear. An early (3 h) effect of pulsed radiofrequency as measured by an increase of c-Fos in the pain-processing neurons of the dorsal horn of rats has been described in the literature. This effect was not mediated by tissue heating. The authors investigated a possible late or long-term effect of three different radiofrequency modalities.

Methods
Cervical laminectomy was performed in 19 male Wistar rats. The cervical dorsal root ganglion was randomly exposed to one of the four interventions: sham, continuous radiofrequency current at 67 centigrades, or pulsed radiofrequency current for 120 s or 8 min. The animals were sacrificed and the spinal cord was prepared for c-Fos labeling 7 days after the intervention.

Results
The number of c-Fos immunoreactive cells in the dorsal horn was significantly increased in the three different radiofrequency modalities as compared with sham. No significant difference was demonstrated between the three active intervention groups.

Conclusions
The authors demonstrated a late neuronal activity in the dorsal horn after exposure of the cervical dorsal root ganglion to different radiofrequency modalities, which was not temperature dependent.