bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations on a Fully Ionized Barium Plasma
Authors: Rynn N. , Hinnov E. , Johnson L. C.
Published: December 2004

A series of spectroscopic measurements in a fully ionized barium plasma column is described and discussed. The plasma was generated in the Q-1 device in a manner similar to that used to make alkali-metal plasmas. The observations show that the density contours and the temperature profiles in the body of the plasma were strongly influenced by conditions at the end plates. The results also indicate that the losses at the ends of the column dominated over the losses in the body of the plasma. Evidence is presented for the existence of internal circulating currents along the confining magnetic field lines in the absence of externally applied potentials. A verification of the Thompson effect in a current-carrying, fully ionized plasma is also presented.
Local Potential and System Stability
Authors: Schechter R. S. , Himmelblau D. M.
Published: December 2004

The concept of the local potential is used to treat questions of hydrodynamic stability. This formalism is shown to evolve into a variational principle which governs the transient behavior of systems. By imposing an assumed approximate structure for the form of the perturbations about the stationary state, it is possible to deduce whether or not the perturbations will grow without bound. The general arguments are illustrated by application to the Bénard problem in order to clarify their significance.
Effect of Collisions on Ion Cyclotron Waves
Authors: Sachs David L.
Published: December 2004

The behavior of a transverse electromagnetic wave propagating in the direction of a uniform magnetic field in an unbounded fully ionized plasma is examined. Linearized kinetic equations with collision terms of the Krook-Bhatnager-Gross type extended by Liboff to include interspecies collisional effects are used in the solution of an inhomogeneous wave equation. The region of ion cyclotron resonance is closely investigated, and the transition of the dispersion relation from the low-temperature collision-dominated regime to the high-temperature regime is observed. It is found that moments of the kinetic equations are adequate in the collision-dominated regime, but the kinetic equation for the ions must be used at higher temperatures. At these higher temperatures a complete solution of the problem requires numerical work near the source plane. Far from the source, explicit solutions for the fields can be written.
Power Balance in Helium Discharges in the C-Stellarator
Authors: Bishop A. S. , Gibson A. , Hinnov E. , Hofmann F. W.
Published: December 2004

Power balance measurements have been carried out for helium discharges in the C-Stellarator over a wide range of Ohmic heating currents. The results show that the power input can be satisfactorily accounted for in terms of power dissipated in radiation, ionization, and heating of the helium. Power loss due to impurity radiation is negligible; that due to charge exchange is shown to be insignificant (except possibly at very low currents). Other mechanisms of power loss appear to play no major role in the power balance analysis.
Diffusion of Electrons in Mutually Perpendicular Electric and Magnetic Fields
Authors: Mouthaan K.
Published: December 2004

The collective behavior of electrons in mutually perpendicular static electric and magnetic fields is considered. A known instability, first described by Buneman, of laminar electron flow in mutually perpendicular electric and magnetic fields is shown to necessitate a statistical description of the motion of the electrons. The motion of the electrons is described as diffusion; the diffusion tensor transverse to the magnetic field is obtained. Buneman's instability of laminar flow is shown to cause the conversion of E × B drift energy into energy of gyration about the magnetic field. The transverse diffusion tensor is obtained from the rate at which the conversion of energy takes place; this rate is taken to be equal to the growth rate of the instability obtained by Buneman. The transverse-diffusion coefficients are found to be proportional to the square of the static electric field and inversely proportional to the cube of the static magnetic field. It is shown how the results may be generalized to the case of diffusion of electrons across a magnetic field in ionized gases, by replacing the square of the velocity E/B by the mean-square thermal velocity of the electrons in the ionized gas. The results are in agreement with experimental results.
Perception of Gaze Direction Based on Luminance Ratio
Authors: Ando Shinki
Published: December 2004

Changing the luminance of one side of the sclera induces an apparent shift of the perceived direction of gaze toward the darker side of the sclera (Ando, 2002 Perception31 657–674). However, when both the sclera and the skin surrounding it were darkened simultaneously as if by a cast shadow, the apparent direction of gaze shifted less than when only the sclera was darkened. The results suggest that one mechanism for gaze judgment is based on a simple analysis of the local luminance ratio between the eye and the surrounding region.
Why Cast Shadows are Expendable: Insensitivity of Human Observers and the Inherent Ambiguity of Cast Shadows in Pictorial Art
Authors: Jacobson Jayme , Werner Steffen
Published: December 2004

The kinds of visual cues artists choose to use or not use in their work can offer insight into perceptual processes. On the basis of the observed paucity of the use of cast shadow in pictorial art, we hypothesized that cast shadows might be relatively expendable as pictorial cues. In this study, we investigated two potential reasons for this expendability: first, viewers might be insensitive to much of the information that cast shadows provide; and, second, ambiguities about what is shadow and what is pigment can often be resolved only through motion—something that static media are ill-equipped to deal with. In experiment 1, we used a visual-search paradigm in which viewers had to determine if there were odd cast shadows in sets of 4, 8, 16, and 32 objects. In experiment 2, viewers had to discriminate between shadow/pigment ambiguities in both still and moving images. Our results demonstrate that viewers are neither particularly sensitive to static cast-shadow incongruities, nor are they able to disambiguate cast shadow from pigment without continuous motion information. Taken together, these results may help explain why cast shadows are relatively rare in static pictorial work.
Genetic variation in Eucalyptus globulus in relation to susceptibility from attack by the southern eucalypt leaf beetle, Chrysophtharta agricola
Authors: Rapley Luke P. , Allen Geoff R. , Potts Brad M.
Published: December 2004

The southern eucalypt leaf beetle, Chrysophtharta agricola (Chapuis), is an outbreak insect pest of commercial Eucalyptus globulus Labill. plantations in south-eastern Australia. We surveyed a young E. globulus family trial in southern Tasmania to determine whether genetic variation existed in the susceptibility of trees to C. agricola field oviposition. The family trial consisted of 225 families, derived from open-pollinated seed collected from native stands at 24 different localities, representing nine geographic subraces. The survey showed that E. globulus subraces from Victoria were significantly more susceptible to C. agricola oviposition than Tasmanian subraces. Significant additive genetic variation within subraces was evident for the number of egg batches, larval clutches and their combination (infestation level), although these heritability scores were all low (egg batches h2op = 0.09; larval clutches h2op = 0.14 and infestation level h2op = 0.11). Subsequent tree defoliation was significantly positively correlated with infestation at a phenotypic, genetic and environmental level. No significant differences in C. agricola oviposition on foliage sprigs was detected among subraces in an ex situ caged oviposition experiment. However, the cage experiment proved to be a good predictor of field oviposition, accounting for 70 and 88% of variation in field oviposition among localities and subraces, respectively.
Adult stem cells from bone marrow stroma differentiate into airway epithelial cells: Potential therapy for cystic fibrosis
Authors: Wang Guoshun , Bunnell Bruce A. , Painter Richard G. , Quiniones Blesilda C. , Tom Susan , Lanson Nicholas A. , Spees Jeffrey L. , Bertucci Donna , Peister Alexandra , Weiss Daniel J. , Valentine Vincent G. , Prockop Darwin J. , Kolls Jay K.
Published: December 2004

Cystic fibrosis (CF), the most prevalent, fatal genetic disorder in the Caucasian population, is caused by mutations of CF transmembrane conductance regulator (CFTR). The mutations of this chloride channel alter the transport of chloride and associated liquid and thereby impair lung defenses. Patients typically succumb to chronic bacterial infections and respiratory failure. Restoration of the abnormal CFTR function to CF airway epithelium is considered the most direct way to treat the disease. In this report, we explore the potential of adult stem cells from bone marrow, referred to as mesenchymal or marrow stromal stem cells (MSCs), to provide a therapy for CF. We found that MSCs possess the capacity of differentiating into airway epithelia. MSCs from CF patients are amenable to
CFTR
gene correction, and expression of CFTR does not influence the pluripotency of MSCs. Moreover, the CFTR-corrected MSCs from CF patients are able to contribute to apical Cl
-
secretion in response to cAMP agonist stimulation, suggesting the possibility of developing cell-based therapy for CF. The
ex vivo
coculture system established in this report offers an invaluable approach for selection of stem-cell populations that may have greater potency in lung differentiation.
The rate of DNA evolution: Effects of body size and temperature on the molecular clock
Authors: Gillooly James F. , Allen Andrew P. , West Geoffrey B. , Brown James H.
Published: December 2004

Observations that rates of molecular evolution vary widely within and among lineages have cast doubts on the existence of a single “molecular clock.” Differences in the timing of evolutionary events estimated from genetic and fossil evidence have raised further questions about the accuracy of molecular clocks. Here, we present a model of nucleotide substitution that combines theory on metabolic rate with the now-classic neutral theory of molecular evolution. The model quantitatively predicts rate heterogeneity and may reconcile differences in molecular- and fossil-estimated dates of evolutionary events. Model predictions are supported by extensive data from mitochondrial and nuclear genomes. By accounting for the effects of body size and temperature on metabolic rate, this model explains heterogeneity in rates of nucleotide substitution in different genes, taxa, and thermal environments. This model also suggests that there is indeed a single molecular clock, as originally proposed by Zuckerkandl and Pauling [Zuckerkandl, E. & Pauling, L. (1965) in
Evolving Genes and Proteins
, eds. Bryson, V. & Vogel, H. J. (Academic, New York), pp. 97–166], but that it “ticks” at a constant substitution rate per unit of mass-specific metabolic energy rather than per unit of time. This model therefore links energy flux and genetic change. More generally, the model suggests that body size and temperature combine to control the overall rate of evolution through their effects on metabolism.
Opposing Roles for Actin in Cdc42p Polarization
Authors: Irazoqui Javier E. , Howell Audrey S. , Theesfeld Chandra L. , Lew Daniel J.
Published: December 2004

In animal and fungal cells, the monomeric GTPase Cdc42p is a key regulator of cell polarity that itself exhibits a polarized distribution in asymmetric cells. Previous work showed that in budding yeast, Cdc42p polarization is unaffected by depolymerization of the actin cytoskeleton (Ayscough et al., J. Cell Biol. 137, 399–416, 1997). Surprisingly, we now report that unlike complete actin depolymerization, partial actin depolymerization leads to the dispersal of Cdc42p from the polarization site in unbudded cells. We provide evidence that dispersal is due to endocytosis associated with cortical actin patches and that actin cables are required to counteract the dispersal and maintain Cdc42p polarity. Thus, although Cdc42p is initially polarized in an actin-independent manner, maintaining that polarity may involve a reinforcing feedback between Cdc42p and polarized actin cables to counteract the dispersing effects of actin-dependent endocytosis. In addition, we report that once a bud has formed, polarized Cdc42p becomes more resistant to dispersal, revealing an unexpected difference between unbudded and budded cells in the organization of the polarization site.
Aurora Kinase Inhibitor ZM447439 Blocks Chromosome-induced Spindle Assembly, the Completion of Chromosome Condensation, and the Establishment of the Spindle Integrity Checkpoint inXenopusEgg Extracts
Authors: Gadea Bedrick B. , Ruderman Joan V.
Published: December 2004

The Aurora family kinases contribute to accurate progression through several mitotic events. ZM447439 (“ZM”), the first Aurora family kinase inhibitor to be developed and characterized, was previously found to interfere with the mitotic spindle integrity checkpoint and chromosome segregation. Here, we have used extracts of Xenopus eggs, which normally proceed through the early embryonic cell cycles in the absence of functional checkpoints, to distinguish between ZM's effects on the basic cell cycle machinery and its effects on checkpoints. ZM clearly had no effect on either the kinetics or amplitude in the oscillations of activity of several key cell cycle regulators. It did, however, have striking effects on chromosome morphology. In the presence of ZM, chromosome condensation began on schedule but then failed to progress properly; instead, the chromosomes underwent premature decondensation during mid-mitosis. ZM strongly interfered with mitotic spindle assembly by inhibiting the formation of microtubules that are nucleated/stabilized by chromatin. By contrast, ZM had little effect on the assembly of microtubules by centrosomes at the spindle poles. Finally, under conditions where the spindle integrity checkpoint was experimentally induced, ZM blocked the establishment, but not the maintenance, of the checkpoint, at a point upstream of the checkpoint protein Mad2. These results show that Aurora kinase activity is required to ensure the maintenance of condensed chromosomes, the generation of chromosome-induced spindle microtubules, and activation of the spindle integrity checkpoint.
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.
Gabapentin Normalizes Spinal Neuronal Responses That Correlate with Behavior in a Rat Model of Cancer-induced Bone Pain
Authors: Donovan-Rodriguez Tansy , Dickenson Anthony H. , Urch Catherine E.
Published: December 2004

Background

Cancer-induced bone pain is a major clinical problem for which current treatments lack full efficacy. Gabapentin is licensed for use in neuropathic pain yet is also effective against inflammatory stimuli in animals.

Methods

A rat model of cancer-induced bone pain using the MRMT-1 cell line injected into the tibia was established to investigate the efficacy of acute (10, 30, 100 mg/kg) and chronic (30 mg/kg) systemic gabapentin on electrophysiological superficial dorsal horn neuronal responses to natural and noxious electrical stimuli, as well as on pain-related behavior.

Results

In electrophysiological studies gabapentin worked both acutely (100 mg/kg) and chronically (30 mg/kg) to normalize the hyperexcitable superficial dorsal horn neuronal response, significantly reducing electrical-evoked and mechanical-evoked but not thermal-evoked responses. The behavioral study showed that chronic gabapentin (30 mg/kg) significantly attenuated pain behavior in MRMT-1 rats, restoring responses to preoperative baseline degrees, and that this attenuation was accompanied by a reversion to normal (non-MRMT-1) wide-dynamic-range: nociceptive specific superficial dorsal horn neuronal profiles.

Conclusions

Pain-related behavior in this rat model of cancer-induced bone pain is strongly linked to hyperexcitability of a population of superficial dorsal horn neurones. Gabapentin normalizes the cancer-induced bone pain induced dorsal horn neuronal changes and attenuates pain behavior. It may therefore provide a novel clinical treatment for cancer-induced bone pain.
Changes in Response Properties and Receptive Fields of Spinal Dorsal Horn Neurons in Rats after Surgical Incision in Hairy Skin
Authors: Kawamata Mikito , Koshizaki Masayuki , Shimada Steven G. , Narimatsu Eichi , Kozuka Yuji , Takahashi Toshiyuki , Namiki Akiyoshi , Collins J G.
Published: December 2004

Background

Mechanical hyperalgesia and allodynia associated with chemical irritant application are mediated by spinal high-threshold (HT) as well as wide-dynamic-range neurons as a result of "central sensitization." Because the pathophysiology of pain is thought to differ depending on the type of injury and may vary between hairy and glabrous skin, the authors examined changes in properties of spinal dorsal horn neurons after surgical incisions in hairy skin of rats to obtain insights into the mechanisms of postoperative pain.

Methods

Withdrawal responses to punctate mechanical stimulation and gentle brushing were measured in awake rats in an area adjacent to the injured site (primary area) and in an area 2 cm from the injured site (secondary area) after 1-cm longitudinal incisions through the hairy skin, fascia, and muscle had been made in the hindquarters. In a separate study, responses of spinal wide-dynamic-range, HT, and low-threshold neurons to nonnoxious and noxious stimuli were recorded before and after similar incisions had been made in the centers of their receptive fields. Effects of spinal application of the gamma-aminobutyric acid A receptor antagonist bicuculline (15 microg) on responses of HT neurons were then studied.

Results

Awake rats showed primary and secondary hyperalgesia to punctate mechanical stimulation 30 min after the incision and thereafter for 4 days and 1 day, respectively. Mechanical allodynia associated with brush stimulation was only seen in the primary area 30 min after the incision and thereafter for 1 day. The incision resulted in increases in activity of wide-dynamic-range neurons (receptive field sizes and responses to both innocuous and noxious stimuli). HT neurons did not respond to innocuous stimulation and showed very small increases or no changes in receptive field size and responses to noxious stimuli after the incision. However, the majority of HT neurons began to respond to innocuous stimuli after application of bicuculline (15 microg/50 microl) to the spinal cord.

Conclusions

The results suggest that wide-dynamic-range neurons are responsible for behavioral hyperexcitability after surgical incision but that HT neurons are not involved in the hyperexcitability, despite the fact that HT neurons are capable of responding to innocuous stimuli by reversal of gamma-aminobutyric acid-mediated inhibition.
Influence of Obesity on Surgical Regional Anesthesia in the Ambulatory Setting: An Analysis of 9,038 Blocks
Authors: Nielsen Karen C. , Guller Ulrich , Steele Susan M. , Klein Stephen M. , Greengrass Roy A. , Pietrobon Ricardo
Published: December 2004

Background

Regional anesthesia is increasing in popularity for ambulatory surgical procedures. Concomitantly, the prevalence of obesity in the United States population is increasing. The objective of the present investigation was to assess the impact of body mass index (BMI) on patient outcomes after ambulatory regional anesthesia.

Methods

This study was based on prospectively collected data including 9,038 blocks performed on 6,920 patients in a single ambulatory surgery center. Patients were categorized into three groups according to their BMI (<25 kg/m2, 25-29 kg/m2, > or =30 kg/m2). Block efficacy, rate of acute complications, postoperative pain (at rest and with movement), postoperative nausea and vomiting, rate of unscheduled hospital admissions, and overall patient satisfaction were assessed. Linear and logistic multivariable analyses were used to obtain the risk-adjusted effect of BMI on these outcomes.

Results

Of all patients 34.8% had a BMI <25 kg/m2, 34.0% were overweight (BMI 25-29 kg/m2), and 31.3% were obese (BMI > or = 30 kg/m2). Patients with BMI > or =30 kg/m2 were 1.62 times more likely to have a failed block (P = 0.04). The unadjusted rate of acute complications was higher in obese patients (P = 0.001). However, when compared with patients with a normal BMI, postoperative pain at rest, unanticipated admissions, and overall satisfaction were similar in overweight and obese patients.

Conclusions

The present investigation shows that obesity is associated with higher block failure and complication rates in surgical regional anesthesia in the ambulatory setting. Nonetheless, the rate of successful blocks and overall satisfaction remained high in patients with increased BMI. Therefore, overweight and obese patients should not be excluded from regional anesthesia procedures in the ambulatory setting.
Does Off-pump Coronary Artery Bypass Reduce Mortality, Morbidity, and Resource Utilization When Compared with Conventional Coronary Artery Bypass? A Meta-analysis of Randomized Trials
Authors: Cheng Davy C. , Bainbridge Daniel , Martin Janet E. , Novick Richard J.
Published: December 2004

The authors undertook a meta-analysis of 37 randomized trials (3369 patients) of off-pump coronary artery bypass surgery versus conventional coronary artery bypass surgery. No significant differences were found for 30-day mortality (odds ratio [OR], 1.02; 95% confidence interval [CI], 0.58-1.80), myocardial infarction (OR, 0.77; 95%CI, 0.48-1.26), stroke (OR, 0.68; 95%CI, 0.33-1.40), renal dysfunction, intraaortic balloon pump, wound infection, rethoracotomy, or reintervention. However, off-pump coronary artery bypass surgery significantly decreased atrial fibrillation (OR, 0.58; 95%CI, 0.44-0.77), transfusion (OR, 0.43; 95%CI, 0.29-0.65), inotrope requirements (OR, 0.48; 95%CI, 0.32-0.73), respiratory infections (OR, 0.41; 95%CI, 0.23-0.74), ventilation time (weighted mean difference, -3.4 h; 95%CI, -5.1 to -1.7 h), intensive care unit stay (weighted mean difference, -0.3 days; 95%CI -0.6 to -0.1 days), and hospital stay (weighted mean difference, -1.0 days; 95%CI -1.5 to -0.5 days). Patency and neurocognitive function results were inconclusive. In-hospital and 1-yr direct costs were generally higher for conventional coronary artery bypass surgery versus off-pump coronary artery bypass surgery. Therefore, this meta-analysis demonstrates that mortality, stroke, myocardial infarction, and renal failure were not reduced in off-pump coronary artery bypass surgery surgery; however, selected short-term and mid-term clinical and resource outcomes were improved compared with conventional coronary artery bypass surgery.
Philosophical Fascination with Whole Historical Texts
Authors: Gorman J. L.
Published: December 2004

Book reviewed in this article:

History and Tropology: The Rise and Fall of Metaphor By F. R. Ankersmit
Why Was There a Crisis of Historicism?
Authors: Megill Allan
Published: December 2004

Book reviewed in this article:

Heidegger, Dilthey, and the Crisis of Historicism By Charles R. Bambach
Theologizing the Human Jesus: An Ancient (and Modern) Approach to Christology Reassessed
Authors: Davidson Ivor
Published: December 2004

Many contemporary Christologies, while paying lip‐service to the primacy of the human Jesus, devote little attention to the theological status of his humanity. They may be deflected from this task by such factors as preference for experienced‐based symbol; the fragmentation of biblical studies and dogmatics; the imperatives of contextual hermeneutics; and the preoccupation with methodology rather than substance. But the human Jesus is only theologically meaningful when viewed on a larger canvas than that of either idealist metaphysics or historical reconstruction. The classical doctrines of the anhypostasis and enhypostasis of Jesus’ humanity offer a still useful way of highlighting the primacy of grace, and, contrary to common caricature, do not undermine the density of his human experience. Such an account needs to be supplemented, however, with a robust pneumatology in order to specify the relevance of the human Jesus for revelation, salvation, anthropology, ethics and eschatology.
In Defence of Karl Barth's Doctrine of the Trinity
Authors: Taylor Iain
Published: December 2004

Two common complaints against Barth's doctrine of the Trinity are here addressed. First it is argued that Barth's adoption of the term Seinsweise, or ‘mode of being’ to refer to the trinitarian persons is not in any way a departure from the traditional doctrine. Second, the suggestion that Barth's doctrine shifts over the course of the Dogmatics is examined and refuted.
A Real Options Approach to Economic Exposure Management
Authors: Capel Jeannette
Published: December 2004

Exchange rate volatility is not only a source of concern for firms but also of profit opportunities. If adjustment costs and lags are low, managers can adjust their input or output decisions to raise the firm’s expected profits. Notwithstanding the resulting higher profit variability, the actual risk perceived by the managers may fall as they are probably more averse to downsiderisk—such as financial distress—than to risk in general. Hence, this paper argues that optimal economic exposure management consists of exploiting the upward profit potential of real exchange rate volatility, while keeping downside risk under control. It is shown that option theory provides useful new principles for economic exposure management by bringing out the crucial role of adjustment costs.
Management Control Systems in NPOs: An Italian Survey
Authors: Baraldi Stefano
Published: December 2004

This paper tries to point out the role and the characteristics of management control systems (MCS) in organisations whose main goal is not for profit (NPO). Are MCS a necessary or (at least) a useful tool to manage these organisations? How have they to fit the typical nature of NPOs? Are the traditional control processes (planning, programming, budgeting, reporting) effective in NPOs? What kind of information do they use? What is the ‘state of the art’ and the degree of sophistication of MCS in NPOs? To address these issues, a survey has been conducted among 76 Italian NPO top managers, and the results are reported in this paper.
Surplus or Deficit – Who Cares? Cross‐subsidy in Colleges of Higher Education
Authors: Lewis Brian , Pendlebury Maurice
Published: December 2004

The traditional ethos of higher education encourages the provision of a broad range of academic subjects aimed at producing overall benefits to society and the economy, rather than focusing on the provision of subjects that can achieve financial viability. Under such an ethos the existence of cross‐subsidy goes largely unquestioned. However, pressures on higher education funding, combined with an increasing emphasis on accountability, performance measurement and value for money mean that attitudes to cross‐subsidy may be changing. This study, which concentrates on one specific sector of higher education, i.e. colleges of higher education, consists of a pilot study at one institution and a sector‐wide survey and examines the extent to which the cross‐subsidy of academic departments is tolerated by senior managers. Although a number of reasons for tolerating cross‐subsidy were supported by the respondents, an analysis of the results reveal much lower levels of support from the finance directors of colleges of higher education than from other senior managers.
Peter Härtlings Hoffmann Oder Die Vielfältige Liebe: Ein Plädoyer Für Mischa?
Authors: Röder Birgit
Published: December 2004

In bislang veröffentlichten Studien zur Biografie E.T.A. Hoffmanns kommt dessen Ehefrau Maria Thekla Michaelina Rorer‐Trzcinska eine höchst untergeordnete Rolle zu, und sie wird fast ausschließlich als durch und durch fantasielose Hausfrau aus dem Lager der Philister oder als duldsame leidgeprüfte Gefährtin des großen Exzentrikers gesehen. Im Gegensatz zu dieser Sichtweise, die sich zum Teil in grotesken, wissenschaftlich unhaltbaren Klischeevorstellungen manifestiert, wird in der vorliegenden Arbeit der Versuch unternommen, diese verzerrte Vorstellung von Mischa neu zu überdenken, und bisher ungestellte Fragen nach der Richtigkeit dieser Interpretationsweise aufzuwerfen. Dabei werden einerseits biografische Fakten zu Rate gezogen, andererseits aber auch Hoffmanns Werk, d. h. dessen fiktionale Darstellung von Liebesbeziehungen untersucht. Abschließend folgt eine Analyse von Peter Härtlings ‘Romanze’Hoffmann oder Die vielfältige Liebe, in der dem Leser – auf überzeugende, wenngleich auf fiktionale Weise – eine Mischa vorgestellt wird, die wesentlich an Charakter und Persönlichkeit gewinnt. Dabei wird die traditionelle Klischeevorstellung von Hoffmanns Ehefrau, aber ebenso die leidenschaftliche Beziehung Hoffmanns zu seiner Gesangsschülerin Julia Mark, in Frage gestellt. Darüber hinaus bietet Härtling eine herausfordernde Alternative an, indem er beiden Frauen (besonders aber Mischa) eine eigene Stimme bzw. Perspektive gewährt.
The estate of merchants in the parliament of 1381
Authors: Liddy Christian D.
Published: December 2004

The discovery among the class of ancient petitions in the Public Record Office of two documents containing lists of members of two parliamentary committees throws new light on the role of the urban element in the medieval English parliament, about which the parliament rolls say very little. This article places the two lists, undated but almost certainly of 1381, in the immediate context of the response of the political community to the Peasants' Revolt, and explores the idea of an estate of merchants meeting in parliament in the second half of the fourteenth century.