bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrafast optics: Imaging and manipulating biological systems
Authors: Sheetz Kraig E. , Squier Jeff
Published: March 2009

The rapid evolution of ultrafast optics technology over the past two decades has opened the window to a broad range of applications in biology and medicine. Compact, reliable, and turn-key ultrafast laser systems are enabling cutting-edge science to take place in everyday laboratories and clinics. Led by the discovery of two-photon excitation fluorescence microscopy nearly 20 years ago, the biological imaging community is exploring unique image contrast mechanisms and pushing spatial and temporal resolution to new limits. Concurrent with advancements in imaging are developments in the precision application of extremely high peak intensities available in ultrashort pulses for disrupting or manipulating targeted locations in biological systems on the submicron scale while leaving surrounding tissue healthy. The ability for scientists to selectively discriminate structures of interest at the cellular and subcellular levels under relevant physiological conditions shows tremendous promise for accelerating the path to understanding biological functions at the most fundamental level.
Effects of long pulse width and high pulsing frequency on surface superhydrophobicity of polytetrafluoroethylene in quasi-direct-current plasma immersion ion implantation
Authors: Kwok Dixon T. K. , Wang Huaiyu , Zhang Yumei , Yeung Kelvin W. K. , Chu Paul K.
Published: March 2009

Long pulse, high frequency quasi-direct-current (dc) oxygen plasma immersion ion implantation (PIII) is utilized to create a superhydrophobic polytetrafluoroethylene (PTFE) surface with a water contact angle of over 150°. This technique allows the use of a high duty cycle without deleterious effects such as extensive sample heating encountered in conventional PIII. Scanning electron microscopy images review submicrometer-nanometer structures on the PTFE surface after long pulse, high frequency PIII indicative of ion implantation. On the other hand, plasma modification is the dominant effect in short pulse, low frequency PIII. Quasi-dc PIII is demonstrated to offer adjustable synergistic plasma and ion beam effects.
Electrostatic force microscopy and potentiometry of realistic nanostructured systems
Authors: Lucchesi Mauro , Privitera Giulia , Labardi Massimiliano , Prevosto Daniele , Capaccioli Simone , Pingue Pasqualantonio
Published: March 2009

We investigate the dependency of electrostatic interaction forces on applied potentials in electrostatic force microscopy (EFM) as well as in related local potentiometry techniques such as Kelvin probe microscopy (KPM). The approximated expression of electrostatic interaction between two conductors, usually employed in EFM and KPM, may loose its validity when probe-sample distance is not very small, as often realized when realistic nanostructured systems with complex topography are investigated. In such conditions, electrostatic interaction does not depend solely on the potential difference between probe and sample, but instead it may depend on the bias applied to each conductor. For instance, electrostatic force can change from repulsive to attractive for certain ranges of applied potentials and probe-sample distances, and this fact cannot be accounted for by approximated models. We propose a general capacitance model, even applicable to more than two conductors, considering values of potentials applied to each of the conductors to determine the resulting forces and force gradients, being able to account for the above phenomenon as well as to describe interactions at larger distances. Results from numerical simulations and experiments on metal stripe electrodes and semiconductor nanowires supporting such scenario in typical regimes of EFM investigations are presented, evidencing the importance of a more rigorous modeling for EFM data interpretation. Furthermore, physical meaning of Kelvin potential as used in KPM applications can also be clarified by means of the reported formalism.
Correlation of lifetime and recombination zone in green phosphorescent organic light-emitting diodes
Authors: Yook Kyoung Soo , Jeon Soon Ok , Joo Chul Woong , Lee Jun Yeob
Published: March 2009

The lifetime of green phosphorescent organic light-emitting diodes was correlated with the charge leakage and recombination zone of the devices. The lifetime of green devices was decreased in the device with an electron leakage out of an emitting layer into a hole transport layer. In particular, the decrease in lifetime at high luminance was significant in the device with an electron leakage into the hole transport layer. In addition, the recombination zone of green devices was shifted from the hole transport layer side to the electron transport layer side during driving.
Empirical relaxation function and spectral density for underdamped vibrations at low temperatures
Authors: Toutounji Mohamad
Published: March 2009

A new relaxation function which accounts for electronic dephasing (electronic phase loss and excited state lifetime) is presented, whose applicability for underdamped motion at low temperatures is examined in detail. This new empirical relaxation function φ(t) yields linear and nonlinear spectral/temporal profiles that render accurate dephasing time in the underdamped regime. The relaxation function φ(t) is normally expressed in terms of the coupling functions Mj′ and Mj″ on which the time evolution of the vibrational modes in question depends. The corresponding spectral density, which is a central quantity in probing dynamics, is derived and compared to that of the multimode Brownian oscillator model. Derivation and discussion of the new position and momentum autocorrelation functions in terms of our new spectral density are presented. While the position autocorrelation function plays a key role in representing solvation structure in polar or nonpolar medium, the momentum correlation function projects out the molecular vibrational motion. The Liouville space generating function (LGF) for harmonic and anharmonic systems is expressed in terms of our new empirical φ(t) and spectral density, leading to more physical observation. Several statistical quantities are derived from the position and momentum correlation function, which in turn contribute to LGF. Model calculations reflecting the infinite population decay in the low temperature limit in linear and nonlinear spectroscopic signals are presented. The herein quantum dipole moment correlation function is compared to that derived in [M. Toutounji, J. Chem. Phys. 118, 5319 (2003)] using mixed quantum-classical dynamics framework, yielding reasonable results, in fact identical at higher temperatures. The results herein are found to be informative, useful, and consistent with experiments.
Surface adsorption phase diagram of O/Ni(110) system: An ab initio atomistic thermodynamics investigation
Authors: Zhang Wei-Bing , Tang Bi-Yu
Published: March 2009

Based on ab initio atomistic thermodynamics model, the surface adsorption diagram of O/Ni(110) system over a wide range of temperature and pressure conditions has been determined. Different surface phases including oxygen adsorption on reconstructed and unreconstructed substrates are considered. Clean nickel surface, p(2×1)-O and p(3×1)f-O, and bulk oxide phase are found to be the most stable phases under different oxygen chemical potential regions. Our calculations suggest that the unreconstructed (n×1)(n=2,3)-O overlayer and p(3×1)i-O phases are just metastable at the equilibrium condition. These results could effectively solve the debate in different experiments and give a consistent description for the reproducibility of overlayer and p(3×1)i-O reconstructed phases.
Transparent conductive oxide layer-less dye-sensitized solar cells consisting of floating electrode with gradient TiOx blocking layer
Authors: Yoshida Yoshikazu , Pandey Shyam S. , Uzaki Kenshiro , Hayase Shuzi , Kono Mitsuru , Yamaguchi Yoshihiro
Published: March 2009

A transparent conductive oxide less dye-sensitized solar cell (TCO-less DSC) consisting of a glass/a floating electrode (FE)/a stained nanoporous titania layer/a gel electrolyte sheet/a Pt layer/a Ti sheet is reported. The FE is composed of a stainless mesh sheet covered with a gradient TiOx layer, which suppressed back-electron transfers from the stainless to electrolytes. The efficiency increased from 2.87% to 4.68% by replacing a conventional dense TiO2 blocking layer with the gradient TiOx layer. The cell in this architecture gave the efficiency of 5.56% after optimization.
Voltage-driven in-plane steering of nematicons
Authors: Piccardi Armando , Peccianti Marco , Assanto Gaetano , Dyadyusha Andriy , Kaczmarek Malgosia
Published: March 2009

Using an external voltage and interdigitated electrodes in a liquid crystalline cell, we demonstrate tunable steering of light beams and spatial solitons without the detrimental walk-off out of the plane of propagation. The results agree well with a simple model describing birefringence and reorientation in uniaxial nematic liquid crystals.
Temporal deposition and spatial distribution of cytoskeletal proteins in the sperm head of an Australian rodent
Authors: Breed William G. , Idriss Dina , Leigh Christopher M. , Oko Richard J.
Published: March 2009

The Australian murine rodent, the plains mouse (Pseudomys australis), possesses a highly complex sperm head, in which there are, in addition to an apical hook, two ventral processes that extend from its upper concave surface. The present study set out to determine the temporal deposition and distribution of the proteins within these structures during late spermiogenesis by light and electron microscopy using various antibodies to bull and laboratory rat sperm-head cytoskeletal proteins. The findings show that there are two phases of protein deposition. In the first phase, perinuclear theca proteins are deposited at the base of the ventral processes around the acrosomal extensions of the developing spermatids. In the second phase, as the ventral processes expand, actin and then perforatorial proteins are laid down during which time the processes become progressively more bilaterally flattened. These various proteins are moulded together to give rise to the two very large cytoskeletal structures that extend from the upper concave surface of the sperm head. They may be involved in binding the spermatozoon to the outer surface of the zona pellucida and/or in aiding the spermatozoon in zona penetration at the time of fertilisation.
Gene expression profile of cumulus cells derived from cumulus - oocyte complexes matured either in vivo or in vitro
Authors: Tesfaye Dawit , Ghanem Nasser , Carter Fiona , Fair Trudee , Sirard Marc-André , Hoelker Michael , Schellander Karl , Lonergan Patrick
Published: March 2009

Although it is well established that maturation conditions have a clear influence on oocyte developmental competence, it is not known whether this could be due to downstream effects of perturbation of the transcript profile of the oocyte’s adjacent cumulus cells. Therefore, the aim of the present study was to compare the transcript profiles of cumulus cells derived from cumulus–oocyte complexes (COCs) matured in vitro or in vivo. Using a previously validated combined synchronisation and superstimulation protocol, COCs were recovered from beef heifer ovaries just before the expected time of the LH surge and matured in vitro, while in vivo-matured COCs were recovered just before ovulation (20 h after the LH surge). A custom-made cDNA microarray containing 2278 granulosa/cumulus transcripts was used for target and dye-swap hybridisations. In all, 64 genes were differentially expressed between the two groups. Transcript abundance of key genes associated with cumulus expansion (TNFAIP6) and regulation of oocyte maturation (INHBA and FST) were upregulated in in vivo-derived cumulus cells. However, cumulus cells derived from IVM COCs were enriched with genes involved in response to stress (HSPA5 and HSP90AB1). Quantitative real-time polymerase chain reaction confirmed the array results for eight of 10 genes selected for validation. The data presented here reveal that differences in oocyte developmental capacity after maturation in vitro or in vivo are accompanied by distinct differences in transcript abundance of the surrounding cumulus cells.
Dietary carbohydrates and amino acids influence oocyte quality in dairy heifers
Authors: Rooke J. A. , Ainslie A. , Watt R. G. , Alink F. M. , McEvoy T. G. , Sinclair K. D. , Garnsworthy P. C. , Webb R.
Published: March 2009

The objective of the present experiment was to determine whether increasing plasma insulin by different nutritional regimes affects oocyte quality. Holstein dairy heifers (eight per treatment) were assigned, using a two times two factorial design, to diets containing either low or high dietary leucine and either low or high dietary starch. Each heifer underwent six sessions of ovum pick-up beginning 25 days after introduction of the diets. Oocyte quality was assessed by development to the blastocyst stage in synthetic oviducal fluid following in vitro fertilisation. Feeding diets containing high leucine resulted in significantly higher plasma free leucine and tyrosine concentrations. The high-starch diet significantly increased plasma insulin but not glucagon concentration, whereas high dietary leucine increased plasma glucagon but not insulin. Oocyte cleavage was not influenced by diet. The high-starch diet, which was associated with a high plasma insulin : glucagon ratio, had adverse effects on oocyte quality that were avoided when leucine intake was increased. There was an association between total plasma free amino acid concentration and oocyte cleavage. Therefore, in dairy heifers dietary amino acids and carbohydrates during antral follicle development appear to mediate effects on oocyte quality by different mechanisms. These findings have implications for both diet formulation and feeding regimes.
Effects of oviductal proteins, including heat shock 70 kDa protein 8, on survival of ram spermatozoa over 48 h in vitro
Authors: Lloyd R. E. , Elliott R. M. A. , Fazeli A. , Watson P. F. , Holt W. V.
Published: March 2009

Following insemination, ram spermatozoa are transported to the isthmus region of the oviduct where they bind to the oviductal epithelial cells (OEC), remaining viable for several hours. The aim of the present study was to begin to decipher which component(s) of the ewe oviduct actively participates in maintaining the viability of ram spermatozoa. A series of experiments was conducted to investigate whether: (1) soluble OEC apical plasma membrane proteins (sAPM) isolated from ewes prolong survival of ram spermatozoa over an extended (48 h) coincubation period at 39°C; (2) a recombinant form of one of these oviductal proteins, namely heat shock 70 kDa protein 8 (HSPA8), prolongs survival of ram spermatozoa; and (3) pretreatment with HSPA8 antibody compromises the ability of sAPM to prolong the survival of ram spermatozoa. Both sAPM and recombinant HSPA8 had a beneficial effect on the viability of ram spermatozoa during coincubation, although both these effects were dose dependent. In contrast, pretreatment with HSPA8 antibody significantly negated the ability of sAPM to maintain the viability of ram spermatozoa. These findings suggest that HSPA8 is an active component of the ewe oviduct that participates in maintaining the viability of ram spermatozoa. This is a potentially valuable observation given that there is a great deal of room for improving existing diluents for storing fresh ram semen.
Large-scale impacts of herbivores on the structural diversity of African savannas
Authors: Asner Gregory P. , Levick Shaun R. , Kennedy-Bowdoin Ty , Knapp David E. , Emerson Ruth , Jacobson James , Colgan Matthew S. , Martin Roberta E.
Published: March 2009

African savannas are undergoing management intensification, and decision makers are increasingly challenged to balance the needs of large herbivore populations with the maintenance of vegetation and ecosystem diversity. Ensuring the sustainability of Africa's natural protected areas requires information on the efficacy of management decisions at large spatial scales, but often neither experimental treatments nor large-scale responses are available for analysis. Using a new airborne remote sensing system, we mapped the three-dimensional (3-D) structure of vegetation at a spatial resolution of 56 cm throughout 1640 ha of savanna after 6-, 22-, 35-, and 41-year exclusions of herbivores, as well as in unprotected areas, across Kruger National Park in South Africa. Areas in which herbivores were excluded over the short term (6 years) contained 38%–80% less bare ground compared with those that were exposed to mammalian herbivory. In the longer-term (> 22 years), the 3-D structure of woody vegetation differed significantly between protected and accessible landscapes, with up to 11-fold greater woody canopy cover in the areas without herbivores. Our maps revealed 2 scales of ecosystem response to herbivore consumption, one broadly mediated by geologic substrate and the other mediated by hillslope-scale variation in soil nutrient availability and moisture conditions. Our results are the first to quantitatively illustrate the extent to which herbivores can affect the 3-D structural diversity of vegetation across large savanna landscapes.
Evidence for liquid water during the high-density to low-density amorphous ice transition
Authors: Kim Chae Un , Barstow Buz , Tate Mark W. , Gruner Sol M.
Published: March 2009

Polymorphism of water has been extensively studied, but controversy still exists over the phase transition between high-density amorphous (HDA) and low-density amorphous (LDA) ice. We report the phase behavior of HDA ice inside high-pressure cryocooled protein crystals. Using X-ray diffraction, we demonstrate that the intermediate states in the temperature range from 80 to 170 K can be reconstructed as a linear combination of HDA and LDA ice, suggesting a first-order transition. We found evidence for a liquid state of water during the ice transition based on the protein crystallographic data. These observations open the possibility that the HDA ice induced by high-pressure cryocooling is a genuine glassy form of high-density liquid.
Postsynaptic glutamate receptor δ family contributes to presynaptic terminal differentiation and establishment of synaptic transmission
Authors: Kuroyanagi Tomoaki , Yokoyama Marie , Hirano Tomoo
Published: March 2009

Synaptic adhesion molecules such as neuroligin are involved in synapse formation, whereas ionotropic transmitter receptors mediate fast synaptic transmission. In mutant mice deficient in the glutamate receptor δ2 subunit (δ2), the number of synapses between granule neurons (GNs) and a Purkinje neuron (PN) in the cerebellum is reduced. Here, we have examined the role of δ2 in synapse formation using culture preparations. First, we found that the size and number of GN presynaptic terminals on a PN in the primary culture prepared from knockout mice were smaller than those in control culture. Next we expressed δ2 in nonneuronal human embryonic kidney (HEK) cells and cocultured them with GNs. Punctate structures expressing marker proteins for glutamatergic presynaptic terminals were accumulated around the HEK cells. Furthermore, HEK cells expressing both δ2 and GluR1, a glutamate receptor subunit forming a functional glutamate-gated ion channel, showed postsynaptic current. Deletion of the extracellular leucine/isoleucine/valine binding protein (LIVBP) domain of δ2 abolished the induction ability, and the LIVBP domain directly fused to a transmembrane sequence was sufficient to induce presynaptic differentiation. Furthermore, a mutant GluR1 whose LIVBP domain was replaced with the δ2 LIVBP domain was sufficient by itself to establish synaptic transmission. Another member of δ glutamate receptor family δ1 also induced presynaptic differentiation. Thus, the δ glutamate receptor subfamily can induce the differentiation of glutamatergic presynaptic terminals and contribute to the establishment of synaptic transmission.
Comprehensive discard reconstruction and abundance estimation using flexible selectivity functions
Authors: Aarts G. , Poos J. J.
Published: March 2009

Aarts, G., and Poos, J. J. 2009. Comprehensive discard reconstruction and abundance estimation using flexible selectivity functions. – ICES Journal of Marine Science, 66: 763–771. The additional mortality caused by discarding may hamper the sustainable use of marine resources, especially if it is not accounted for in stock assessment and fisheries management. Generally, long and precise time‐series on age-structured landings exist, but historical discard estimates are often lacking or imprecise. The flatfish fishery in the North Sea is a mixed fishery targeting mainly sole and plaice. Owing to the gear characteristics and a minimum landing size for these species, considerable discarding occurs, especially for juvenile plaice. Discard samples collected by on-board observers are available since 1999 from a limited number of commercial fishing trips. Here, we develop a statistical catch-at-age model with flexible selectivity functions to reconstruct historical discards and estimate stock abundance. We do not rely on simple predefined selectivity ogives, but use spline smoothers to capture the unknown non-linear selectivity and discard patterns, and allow these to vary in time. The model is fitted to the age-structured landings, discards, and survey data, the most appropriate model is selected, and estimates of uncertainty are obtained.
Guidelines for Cardiac Management in Noncardiac Surgery Are Poorly Implemented in Clinical Practice
Authors: Hoeks Sanne E. , Scholte op Reimer Wilma J. M. , Lenzen Mattie J. , van Urk Hero , Jörning Paul J. G. , Boersma Eric , Simoons Maarten L. , Bax Jeroen J. , Poldermans Don
Published: March 2009

Background

The American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery recommend an algorithm for a stepwise approach to preoperative cardiac assessment in vascular surgery patients. The authors' main objective was to determine adherence to the ACC/AHA guidelines on perioperative care in daily clinical practice.

Methods

Between May and December 2004, data on 711 consecutive peripheral vascular surgery patients were collected from 11 hospitals in The Netherlands. This survey was conducted within the infrastructure of the Euro Heart Survey Programme. The authors retrospectively applied the ACC/AHA guideline algorithm to each patient in their data set and subsequently compared observed clinical practice data with these recommendations.

Results

Although 185 of the total 711 patients (26%) fulfilled the ACC/AHA guideline criteria to recommend preoperative noninvasive cardiac testing, clinicians had performed testing in only 38 of those cases (21%). Conversely, of the 526 patients for whom noninvasive testing was not recommended, guidelines were followed in 467 patients (89%). Overall, patients who had not been tested, irrespective of guideline recommendation, received less cardioprotective medications, whereas patients who underwent noninvasive testing were significantly more often treated with cardiovascular drugs (beta-blockers 43% vs. 77%, statins 52% vs. 83%, platelet inhibitors 80% vs. 85%, respectively; all P < 0.05). Moreover, the authors did not observe significant differences in cardiovascular medical therapy between patients with a normal test result and patients with an abnormal test result.

Conclusion

This survey showed poor agreement between ACC/AHA guideline recommendations and daily clinical practice. Only one of each five patients underwent noninvasive testing when recommended. Furthermore, patients who had not undergone testing despite recommendations received as little cardiac management as the low-risk population.
Accuracy of Cerebral Monitoring in Detecting Cerebral Ischemia during Carotid Endarterectomy
Authors: Moritz Stefan , Kasprzak Piotr , Arlt Matthias , Taeger Kai , Metz Christoph
Published: March 2009

Background

This study compares the accuracy of cerebral monitoring systems in detecting cerebral ischemia during carotid endarterectomy.

Methods

The authors compared transcranial Doppler sonography (TCD), near-infrared spectroscopy (NIRS), stump pressure (SP) measurement, and somatosensory evoked potentials (SEP) in 48 patients undergoing carotid surgery during regional anesthesia. Cerebral ischemia was assumed when neurologic deterioration occurred. During clamping, the minimum mean middle cerebral artery velocity (TCD(min)), its percentage change (TCD%), the minimum regional saturation of oxygen (NIRS(min)), its percentage change (NIRS%), the mean SP, and the changes of SEP amplitude were recorded. To analyze the corresponding sensitivity and specificity of each parameter, the authors performed receiver operating characteristic analysis.

Results

Neurologic deterioration occurred in 12 patients. SP and NIRS were successfully performed in all patients. TCD monitoring was not possible in 10 (21%); SEP was not possible in 2 patients (4%). All parameters provided the ability to distinguish between ischemic and nonischemic patients. TCD% and NIRS% showed significantly better discrimination than TCD(min) and NIRS(min) (P < 0.05). The highest area under the curve (AUC) was found for TCD% (AUC = 0.973), but there was no significant difference compared with NIRS% (AUC = 0.905) and SP (AUC = 0.925). The lowest AUC was found for SEP (AUC = 0.749), which was significantly lower than that for TCD%, NIRS%, and SP.

Conclusions

TCD%, NIRS%, and SP measurement provide similar accuracy for the detection of cerebral ischemia during carotid surgery. Lower accuracy was found for SEP monitoring. Because of the high rate of technical difficulties (21%), TCD monitoring was the least practical of the investigated monitoring devices.
Effects of Age and Emotionality on the Effectiveness of Midazolam Administered Preoperatively to Children
Authors: Kain Zeev N. , MacLaren Jill , McClain Brenda C. , Saadat Haleh , Wang Shu-Ming , Mayes Linda C. , Anderson George M.
Published: March 2009

Background

Multiple studies document the beneficial effect of midazolam on preoperative anxiety in children. Many clinicians report, however, that some children may in fact not benefit from the administration of this drug.

Methods

After screening for relevant exclusion criteria, children undergoing surgery were enrolled in the study (n = 262) and received 0.5 mg/kg oral midazolam at 20-40 min before induction of anesthesia. Personality instruments were administered to all children, and anxiety levels were evaluated before and after administration of midazolam as well as during induction of anesthesia. Blood was drawn during the induction process and later analyzed for midazolam levels. A priori definitions of responders and nonresponders to midazolam were established using a multidisciplinary task force, videotapes of induction, and a validated and reliable anxiety scale, the modified Yale Preoperative Anxiety Scale.

Results

While 57% of all children scored at the minimum of the modified Yale Preoperative anxiety scale, 14.1% of children fell in the a priori defined group of midazolam nonresponders. Midazolam blood levels (94 +/- 41 vs. 109 +/- 40 ng/ml) and timing between administration of midazolam and induction (28 +/- 9 vs. 29 +/- 8 min) did not differ between midazolam responders and nonresponders. In contrast, midazolam nonresponders were younger (4.2 +/- 2.3 vs. 5.9 +/- 2.0 yr), more anxious preoperatively (49.7 +/- 22.9 vs. 38.3 +/- 19.1), and higher in emotionality (13.6 +/- 3.6 vs. 11.3 +/- 3.8) as compared with responders (P < 0.05).

Conclusions

Although midazolam is an effective anxiolytic for most children, 14.1% of children still exhibit extreme distress. This subgroup is younger, more emotional, and more anxious at baseline. Future studies are needed to determine the best strategy to treat these children.
Effects of Extreme Hemodilution during Cardiac Surgery on Cognitive Function in the Elderly
Authors: Mathew Joseph P. , Mackensen G Burkhard , Phillips-Bute Barbara , Stafford-Smith Mark , Podgoreanu Mihai V. , Grocott Hilary P. , Hill Steven E. , Smith Peter K. , Blumenthal James A. , Reves J G. , Newman Mark F.
Published: March 2009

Background

Strategies for neuroprotection including hypothermia and hemodilution have been routinely practiced since the inception of cardiopulmonary bypass. Yet postoperative neurocognitive deficits that diminish the quality of life of cardiac surgery patients are frequent. Because there is uncertainty regarding the impact of hemodilution on perioperative organ function, the authors hypothesized that extreme hemodilution during cardiac surgery would increase the frequency and severity of postoperative neurocognitive deficits.

Methods

Patients undergoing coronary artery bypass grafting surgery were randomly assigned to either moderate hemodilution (hematocrit on cardiopulmonary bypass >or=27%) or profound hemodilution (hematocrit on cardiopulmonary bypass of 15-18%). Cognitive function was measured preoperatively and 6 weeks postoperatively. The effect of hemodilution on postoperative cognition was tested using multivariable modeling accounting for age, years of education, and baseline levels of cognition.

Results

After randomization of 108 patients, the trial was terminated by the Data Safety and Monitoring Board due to the significant occurrence of adverse events, which primarily involved pulmonary complications in the moderate hemodilution group. Multivariable analysis revealed an interaction between hemodilution and age wherein older patients in the profound hemodilution group experienced greater neurocognitive decline (P = 0.03).

Conclusions

In this prospective, randomized study of hemodilution during cardiac surgery with cardiopulmonary bypass in adults, the authors report an early termination of the study because of an increase in adverse events. They also observed greater neurocognitive impairment among older patients receiving extreme hemodilution.
4-Aminopyridine Restores Impaired Hypoxic Pulmonary Vasoconstriction in Endotoxemic Mice
Authors: Spöhr Fabian , Busch Cornelius J. , Reich Christian , Motsch Johann , Gebhard Martha M. , Kuebler Wolfgang M. , Bloch Kenneth D. , Weimann Jörg
Published: March 2009

Background

Hypoxic pulmonary vasoconstriction (HPV) is impaired during inflammatory lung processes such as pneumonia or the acute respiratory distress syndrome. Voltage-gated potassium channels play a central role in mediating HPV. The aim of this study was to determine whether 4-aminopyridine (4-AP), a known voltage-gated potassium channel inhibitor, may restore HPV in sepsis.

Methods

The effects of 0.01, 0.1, and 1.0 mm 4-AP on HPV responsiveness were assessed in isolated lungs of untreated mice and of mice 18 h after lipopolysaccharide injection (20 mg/kg intraperitoneal Escherichia coli 0111:B4 lipopolysaccharide). HPV was quantified as the increase in perfusion pressure in response to hypoxic ventilation in percent of baseline perfusion pressure. Intrinsic pulmonary vascular resistance (R0) and pulmonary vascular distensibility (alpha) were determined by nonlinear regression analysis of pulmonary vascular pressure-flow curves generated during normoxic and hypoxic ventilation, respectively.

Results

HPV was impaired in lungs isolated from lipopolysaccharide-challenged mice. Addition of 4-AP to the perfusate did not alter HPV responsiveness in untreated mice but dose dependently restored HPV in endotoxemic mice. Analysis of pulmonary vascular pressure-flow curves revealed that 4-AP (1) counteracted the observed lipopolysaccharide-induced changes in alpha and R0 under normoxic conditions and (2) augmented the hypoxia-induced increase in R0 in lungs of endotoxemic mice.

Conclusions

This study demonstrates that lipopolysaccharide-induced pulmonary vascular hyporesponsiveness to hypoxia can be restored by 4-AP in murine endotoxemia and, thus, may be a new therapeutic approach to treat patients with hypoxemia due to impaired HPV.
Exogenous Ethyl Pyruvate versus Pyruvate during Metabolic Recovery after Oxidative Stress in Neonatal Rat Cerebrocortical Slices
Authors: Zeng Jianying , Liu Jia , Yang Guo-Yuan , Kelly Mark J. S. , James Thomas L. , Litt Lawrence
Published: March 2009

Background

Exogenous pyruvate and ethyl pyruvate (EP), the key ingredient in a new Ringer's solution in clinical trials, are antioxidants as well as metabolic substrates. In vivo studies show both to be protective in oxidative stress, with EP being better. The authors used an acute rat brain slice preparation to compare EP and pyruvate rescue after H(2)O(2) oxidative stress, asking whether EP was again better and whether its actions were exclusively metabolic.

Methods

Oxygenated neonatal P7 cerebrocortical slices were exposed for 1 h to 2 mM H(2)O(2), and recovered for 4 h with artificial cerebrospinal fluid having 2 mM glucose and (1) 20 mM EP, (2) 20 mM pyruvate, or (3) 1 mM of the nonmetabolizable radical scavenger N-tert-butyl-alpha-phenylnitrone (PBN). Perchloric acid extracts were studied with 31P/1H nuclear magnetic resonance at 14.1 T. Acute cell injury was assessed by counting terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL)-stained cells.

Results

At the end of recovery, preservation of adenosine triphosphate and N-acetylaspartate was better with EP than with pyruvate. Adenosine triphosphate preservation was best when PBN and EP were coadministered. 1H nuclear magnetic resonance revealed changes in lactate, alanine, gamma-aminobutyric acid, glutamate, glutamine, succinate, taurine, and myoinositol. Two-dimensional [1H-13C] heteronuclear single quantum coherence spectroscopy found that 13C-EP administration produced the same tricarboxylic acid metabolites as C-pyruvate. TUNEL-positive cell percentages with EP were less than half of those for PBN or pyruvate rescue (P < 0.05).

Conclusion

EP enters cells, provides pyruvate as a tricarboxylic acid substrate, and is more protective. Although EP provides metabolic protection of adenosine triphosphate levels, it does not maximize antioxidant protection.
Intramuscular Injection of Sevoflurane Detects Malignant Hyperthermia Predisposition in Susceptible Pigs
Authors: Schuster Frank , Metterlein Thomas , Negele Sabrina , Gardill Annegret , Schwemmer Ulrich , Roewer Norbert , Anetseder Martin
Published: March 2009

Background

The authors hypothesized that intramuscular sevoflurane injection allows diagnostic differentiation between malignant hyperthermia-susceptible (MHS) and -nonsusceptible (MHN) pigs by measurement of intramuscular lactate and carbon dioxide partial pressure (PCO2), and that dantrolene reduces the sevoflurane-induced PCO2 increase.

Methods

With approval of the local animal care committee, microdialysis probes with attached microtubing for sevoflurane injection were placed in the adductor muscles of nine MHS and six MHN pigs, and PCO2 probes with microtubing were positioned in the triceps muscle of eight MHS and six MHN pigs. After equilibration, sevoflurane boluses at different concentrations and a sevoflurane-dantrolene bolus were injected synchronously. Lactate, pyruvate, and glucose as well as PCO2 were measured spectrophotometrically, and the rate of PCO2 increase was calculated.

Results

Intramuscular sevoflurane injection increased local lactate and PCO2 dose dependently, and significantly higher in MHS than in MHN pigs. Measurement of the rate of PCO2 increase allowed a distinct differentiation between single MHS and MHN pigs. No significant increase in PCO2 was found with sevoflurane and dantrolene.

Conclusions

Local sevoflurane induces a hypermetabolic reaction measured by PCO2 and lactate increases. The reduced PCO2 increase in MHS after sevoflurane and dantrolene injection is likely to be a result of the sevoflurane-mediated calcium release and its antagonism by dantrolene. Sevoflurane may be useful for a less invasive diagnostic test for malignant hyperthermia in humans.
Fiberoptic Intubation and Laryngeal Morbidity
Authors: Heidegger Thomas , Starzyk Lukas , Villiger Cornelia R. , Schumacher Stefan , Studer Rolf , Peter Barbara , Nuebling Matthias , Gerig Hans J. , Schnider Thomas W.
Published: March 2009

Background

Tracheal intubation with neuromuscular blocking agents is associated with a low incidence of minor vocal cord sequelae (8%). The aim of this noninferiority trial was to demonstrate that the frequency of vocal cord sequelae after fiberoptic intubation with a flexible silicone tube without neuromuscular blocking agents was less than 25% (maximum tolerable inferiority).

Methods

Two-hundred seventy patients were prospectively randomized to two groups. All intubations were performed by anesthesiologists with extensive experience in fiberoptic and conventional techniques. Fiberoptic nasotracheal intubation consisted of a bolus dose of 2 microg/kg fentanyl; 0.25 ml cocaine instillation, 10%, into nasal canals; cricothyroid injection of 2 ml lidocaine, 1%; bronchoscopy; administration of 0.3 mg/kg etomidate; and advancing a flexible silicone tube after loss of consciousness. Orotracheal intubation was performed with a polyvinyl chloride tube after induction with 2 microg/kg fentanyl, 2 mg/kg propofol, and 0.6 mg/kg rocuronium. Patients were examined by laryngoscopy before surgery, 24 h after surgery, and daily until complete restitution. Postoperative hoarseness was assessed by a standardized interview.

Results

The incidence of vocal cord sequelae was 11 out of 130 (8.5%) in the fiberoptic group versus 12 out of 129 (9.3%) in the control group (chi-square = 0.057, df = 1, P = 0.81; upper limit of the one-sided 95% confidence interval for the difference: +5.1%). There were no persistent injuries. The incidence of postoperative hoarseness was 4% in both groups.

Conclusions

Because fiberoptic intubation without neuromuscular blocking agents is safe regarding vocal cord sequelae, routine use is justified for anesthesiologists experienced in this technique.
Presynaptic and Postsynaptic Effects of the Anesthetics Sevoflurane and Nitrous Oxide in the Human Spinal Cord
Authors: Baars Jan H. , Benzke Michael , von Dincklage Falk , Reiche Josephine , Schlattmann Peter , Rehberg Benno
Published: March 2009

Background

Reduced spinal excitability contributes to the suppression of movement responses to noxious stimuli during the anesthetic state. This study examines and compares presynaptic and postsynaptic effects of two anesthetics in the human spinal cord.

Methods

The authors tested two parameters during the administration of 0.8 vol% sevoflurane or 40 vol% nitrous oxide compared with control states before and after drug administration: (1) the size of the soleus H reflex (integrating presynaptic and postsynaptic effects) at increasing stimulus intensities (recruitment curve) and (2) the amount of presynaptic inhibition on Ia afferents of the quadriceps femoris, evaluated by the heteronymous facilitation of the soleus H reflex caused by a conditioning stimulation of the femoral nerve. The study was performed in 10 subjects for each drug.

Results

At the chosen concentrations, the maximum H reflex was reduced by 26.3 +/- 8.4% (mean +/- SD) during sevoflurane and by 33.5 +/- 15.6% during nitrous oxide administration. The averaged recruitment curves were similarly depressed under the influence of the two drugs. The reduction of H-reflex facilitation was significantly stronger for sevoflurane (28.8 +/- 20.0%) than for nitrous oxide administration (6.2 +/- 26.4%).

Conclusions

These results demonstrate in humans presynaptic effects of the volatile anesthetic sevoflurane but not of nitrous oxide. A possible explanation for this difference may be the different potency of the respective drugs in enhancing gamma-aminobutyric acid type A receptor-mediated inhibition, because presynaptic inhibition in the spinal cord involves this receptor subtype.
Intracranial Venous Thrombosis in the Parturient
Authors: Lockhart Ellen M. , Baysinger Curtis L. , Warltier David C.
Published: March 2009

Intracranial venous thrombosis is a rare but potentially fatal complication of pregnancy and the postpartum period. The presenting symptoms can mimic those of a postdural puncture headache and are easily misdiagnosed, especially in a parturient who has undergone regional anesthesia. The incidence of 10-20 per 100,000 is likely higher than reported. The etiology, clinical presentation and course, risk factors, management, and relation of intracranial venous thrombosis to pregnancy are presented. Published case reports and series of intracranial venous thrombosis that have either occurred during the puerperium or involved women of childbearing age after dural puncture are summarized. Finally, the diagnosis and management of intracranial venous thrombosis in parturients, focusing on parturients who have undergone regional anesthesia, is discussed. When intracranial venous thrombosis occurs in a parturient after regional anesthesia, it is often treated as a post-dural puncture headache.
A Retrospective Assessment of Magnetic Resonance Cholangiopancreatography in Children
Authors: Tipnis Neelesh A , Dua Kulwinder S , Werlin Steven L
Published: March 2009

Objective:

To evaluate the utility of magnetic resonance cholangiopancreatography (MRCP) in children and to compare MRCP with direct cholangiopancreatography (CP).

Materials and Methods:

We performed an unblinded, retrospective chart review of 32 children (ages 0–18 years, 17 male) who underwent MRCP between January 2002 and June 2005. MRCP, endoscopic retrograde cholangiopancreatography (ERCP), percutaneous fluoroscopic or intraoperative studies of the pancreatobiliary tree, and clinical outcomes were evaluated.

Results:

Seventeen (52%) children had MRCP alone, 15 (48%) had both MR and direct CP. MRCP results correlated with other evaluative methods in 14/15 (93%) cases. There was 1 false positive (anomalous pancreatic duct union) and 0 false negatives for anatomic abnormalities. Therapeutic intervention was performed in 7 of 28 children initially evaluated by MRCP (2 sphincter of Oddi dysfunction, 2 choledocholithiasis, 2 primary sclerosing cholangitis, 1 congenital hepatic cysts) and 1 of 4 children initially evaluated by ERCP (primary sclerosing cholangitis). All 17 children initially evaluated by MRCP had no change in clinical status to suggest a missed anatomic lesion or therapeutic opportunity.

Conclusions:

In this retrospective study, MRCP was sensitive and specific in identifying anatomic abnormalities of the pancreatobiliary tree in children. MRCP should be considered before direct CP to evaluate anatomic abnormalities of the pancreatobiliary tree.
The Effect of Different Topical Negative Pressures on Microvascular Blood Flow in Reperfused Myocardium during Hypothermia
Authors: Lindstedt Sandra , Malmsjö Malin , Ingemansson Richard
Published: March 2009

Objective

Hypothermia is known to limit the extent of myocardial infarction. The earlier hypothermia is applied to an ischemic myocardium, the more tissue can be salvaged. Topical negative pressure (TNP) is known to increase blood flow and stimulate angiogenesis in subcutaneous tissue and skeletal muscle. We have previously shown that a myocardial TNP of −50 mm Hg significantly increases microvascular blood flow in the underlying myocardium in ischemic and reperfused porcine myocardium. The present study was designed to elucidate the effect of different TNP levels on microvascular blood flow in reperfused myocardium during hypothermia.

Methods

Seven pigs underwent median sternotomy. The microvascular blood flow in the myocardium was recorded before and after the application of −50, −75, −100, −125, and −150 mm Hg using laser Doppler velocimetry. Analysis was performed in the epicardium and at a depth of 6 to 8 mm in the myocardium after 40 minutes of occlusion of the left anterior descending artery followed by cooling to 31°C, and reperfusion for another 20 minutes.

Results

A TNP of −50 mm Hg significantly increased blood the flow in the epicardium, from 116.7 ± 10.0 PU to 244.5 ± 52.6 PU (*P < 0.05) at 31°C. A TNP of −50 mm Hg significantly increased microvascular blood flow in the myocardium, from 155.0 ± 8.4 PU to 236.7 ± 61.5 PU (*P < 0.05).

Conclusions

Only a TNP of −50 mm Hg, applied over the left anterior descending artery region in reperfused hypothermic myocardium significantly increased the microvascular blood flow in the epicardium and in the myocardium.
Nasolacrimal Duct Orifice Cysts in Adults: A Previously Unrecognized, Easily Treatable Cause of Epiphora
Authors: DelGaudio John M. , Wojno Ted
Published: March 2009

Background: Epiphora is a common problem evaluated by ophthalmologists and otolaryngologists. It is typically the result of obstruction at some level of the nasolacrimal system, either the canaliculi, sac, or duct. Multiple etiologies exist, including scarring from infection or trauma, tumors, or masses. Cysts of the nasolacrimal duct orifice (dacryocystoceles) in the inferior meatus have been described in neonates, usually presenting as obstructive nasal masses shortly after birth. Nasolacrimal duct orifice cysts have not been described in the adult population in the medical literature.

Patients: Three patients were identified with epiphora as a result of cysts in the inferior meatus at the opening of the nasolacrimal duct. All patients presented with constant epiphora and were referred for dacryocystorhinostomy by an ophthalmologist or an otolaryngologist. None of the patients had a previous history of nasolacrimal duct (NLD) surgery. One patient had previous endoscopic sinus surgery for nasal polyps. Cysts were identified by nasal endoscopy of the inferior meatus in all patients.

Results: All patients underwent endoscopic resection of the inferior meatus cyst to relieve the obstruction of the NLD. Two procedures were performed under general anesthesia and one under intravenous sedation. All patients had complete relief of epiphora and have had no evidence of recurrence of the symptoms or the cyst in 4 to 10 months follow‐up.

Conclusions: NLD orifice cysts are easily correctable causes of epiphora. Routine inferior meatus endoscopy should be routinely performed in patients with epiphora to identify whether on not this pathology is present prior to performing dacryocystorhinostomy.