bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analgesic Effects of Gabapentin after Spinal Surgery
Authors: Turan Alparslan , Karamanlıoğlu Beyhan , Memiş Dilek , Hamamcıoglu Mustafa Kemal , Tükenmez Barış , Pamukçu Zafer , Kurt Imran 
Published: March 2004

Background
A combination of opioid and nonopioid analgesic drugs may improve the quality of postoperative analgesia as well as reduce opioid requirements and their associated side effects. Studies have shown synergism between gabapentin and morphine in animal and human experiments and in the treatment of incisional pain. Therefore, the authors investigated, in a randomized, placebo-controlled, double-blind study, the effects of gabapentin on acute postoperative pain and morphine consumption in patients undergoing spinal surgery.

Methods
After standard premedication, 25 patients in the control group received oral placebo, and 25 patients in the gabapentin group received 1,200 mg of gabapentin, 1 h before surgery in a randomized fashion. Anesthesia was induced with propofol and cisatracurium and was maintained with sevoflurane and remifentanil. The total intraoperative remifentanil consumption by each patient was noted. All patients postoperatively received patient-controlled analgesia with morphine (1 mg/ml) with an incremental dose of 2 mg, a lockout interval of 10 min, and a 4-h limit of 40 mg. The incremental dose was increased to 3 mg, and the 4-h limit to 50 mg, if analgesia was inadequate after 1 h. Patients were questioned for the first 1 h in the PACU and were later evaluated in the ward at 1, 2, 4, 6, 12, and 24 h. Pain scores, heart rate, oxygen saturation measured by pulse oximetry, mean blood pressure, respiratory rate, sedation, morphine use, and total dose of morphine were recorded.

Results
Overall, pain scores at 1, 2, and 4 h were significantly lower in the gabapentin group when compared with the placebo group. Total morphine consumption in the gabapentin group was 16.3 +/- 8.9 mg (mean +/- SD) versus 42.8 +/- 10.9 mg in the placebo patients. The incidence of vomiting and urinary retention was significantly (P < 0.05) higher in the placebo group, but there was no difference in incidence of other adverse effects between the groups.

Conclusions
Preoperative oral gabapentin decreased pain scores in the early postoperative period and postoperative morphine consumption in spinal surgery patients while decreasing some morphine-associated side effects.
Meperidine Suppresses the Excitability of Spinal Dorsal Horn Neurons
Authors: Wolff Matthias , Olschewski Andrea , Vogel Werner , Hempelmann Gunter 
Published: March 2004

Background
In addition to local anesthetics, meperidine has been successfully used for local anesthesia. When applied intrathecally, the dorsal horn neurons of the superficial laminae are exposed to high concentrations of meperidine. These cells represent an important point for the transmission of pain information. This study investigated the blocking effects of meperidine on different ionic currents of spinal dorsal horn neurons and, in particular, its impact on the generation of action potentials.

Methods
Using a combination of the patch clamp technique and the entire soma isolation method, the action of meperidine on voltage-gated Na+ and K+ currents in spinal dorsal horn neurons of rats was described. Current clamp recordings from intact neurons showed the functional relevance of the ion current blockade for the generation of action potentials.

Results
Externally applied meperidine reversibly blocked voltage-gated Na+ currents with a half-maximum inhibiting concentration (IC50) of 112 microM. During repetitive stimulation, a slight phasic block occurred. In addition, A-type K+ currents and delayed-rectifier K+ currents were affected in a dose-dependent manner, with IC50 values of 102 and 52 microM, respectively. In the current clamp mode, single action potentials were suppressed by meperidine. The firing frequency was lowered to 54% at concentrations (100 microM) insufficient for the suppression of a single action potential.

Conclusions
Meperidine inhibits the complex mechanism of generating action potentials in spinal dorsal horn neurons by the blockade of voltage-gated Na+ and K+ channels. This can contribute to the local anesthetic effect of meperidine during spinal anesthesia.
Repeated Dosing with Oral Allosteric Modulator of Adenosine A1 Receptor Produces Tolerance in Rats with Neuropathic Pain
Authors: Li Xinhui , Bantel Carsten , Conklin Dawn , Childers Steven R. , Eisenach James C. 
Published: March 2004

Background
The positive allosteric adenosine receptor modulator, T62 (2-amino-3-(4-chlorobenzoyl)-5,6,7,8-tetrahydrobenzothiophene), has been shown to reduce mechanical allodynia in a rat model of neuropathic pain. However, whether chronic oral T62 retains efficacy in this pain model has not been examined. Therefore, the authors studied antiallodynic effects of chronic oral T62 in spinal nerved-ligated rats, as well as motor and sedative behavioral effects.

Methods
Oral T62, 100 mg/kg, or oral oil was applied daily to spinal nerve-ligated rats for 4 weeks, with rat weights examined daily. Sedation, placing and ambulation scores, and withdrawal threshold were observed for 3 h daily for the first 2 weeks and then once a week. At the end of observation, the animals were killed, and the spinal tissues were collected for radioligand binding. In addition, withdrawal thresholds were also observed in rats with 5 days of treatment with 50 mg/kg oral T62. Furthermore, the effects of intrathecal adenosine on rats with oral T62 or oil treatment were compared.

Results
Chronic oral T62, at 100 mg/kg, initially returned the withdrawal threshold to mechanical testing to preinjury levels, with minor or no sedative or motor effects. Tolerance was observed, with a 60% loss of most possible effects in antiallodynia within 5 days of daily administration. Similarly, tolerance also occurred with chronic oral T62 at 50 mg/kg but did not alter the effect of intrathecal adenosine. Furthermore, 4 weeks of exposure to 100 mg/kg T62 resulted in a small reduction in spinal cord A1 receptor number.

Conclusion
The results imply that chronically administered A1 adenosine modulators lose efficacy over time, partly as a result of receptor down-regulation.
Possible Mechanism of Irreversible Nerve Injury Caused by Local Anesthetics
Authors: Kitagawa Norihito , Oda Mayuko , Totoki Tadahide 
Published: March 2004

Background
Irreversible nerve injury may result from neural membrane lysis due to the detergent properties of local anesthetics. This study aimed to investigate whether local anesthetics display the same properties as detergents and whether they disrupt the model membrane at high concentrations.

Methods
Concentrations at which dodecyltrimethylammonium chloride and four local anesthetic (dibucaine, tetracaine, lidocaine, and procaine) molecules exhibit self-aggregation in aqueous solutions were measured using an anesthetic cation-sensitive electrode. Light-scattering measurements in a model membrane solution were also performed at increasing drug concentrations. The concentration at which drugs caused membrane disruption was determined as the point at which scattering intensity decreased. Osmotic pressures of anesthetic agents at these concentrations were also determined.

Results
Concentrations of dodecyltrimethylammonium chloride, dibucaine, tetracaine, lidocaine, and procaine at which aggregation occurred were 0.15, 0.6, 1.1, 5.3, and 7.6%, respectively. Drug concentrations causing membrane disruption were 0.09% (dodecyltrimethylammonium chloride), 0.5% (dibucaine), 1.0% (tetracaine), 5.0% (lidocaine), 10.2% (procaine), and 20% (glucose), and osmotic pressures at these concentrations were 278, 293, 329, 581, 728, and 1,868 mOsm/kg H2O, respectively.

Conclusions
These results show that all four local anesthetics form molecular aggregations in the same manner as dodecyltrimethylammonium chloride, a common surfactant. At osmotic pressures insufficient to affect the membrane, local anesthetics caused membrane disruption at the same concentrations at which molecular aggregation occurred. This shows that disruption of the model membrane results from the detergent nature of local anesthetics. Nerve membrane solubilization by highly concentrated local anesthetics may cause irreversible neural injury.
Background Infusion Is Not Beneficial during Labor Patient-controlled Analgesia with 0.1% Ropivacaine plus 0.5 μg/ml Sufentanil
Authors: Boselli Emmanuel , Debon Richard , Cimino Yann , Rimmelé Thomas , Allaouchiche Bernard , Chassard Dominique 
Published: March 2004

Background
Although patient-controlled epidural analgesia (PCEA) during labor has been extensively studied in recent clinical trials, the role of a background infusion associated with self-administered boluses is still debated. The authors designed a study to assess whether the use of PCEA with or without background infusion could improve the comfort of parturients and their satisfaction during labor and delivery without affecting the total consumption of local anesthetics.

Methods
One hundred thirty-three laboring parturients requesting epidural analgesia administered via PCEA with a solution of 0.1% ropivacaine plus 0.5 microg/ml sufentanil were randomly assigned to four groups, according to the rate of background infusion used (0, 3, 6, and 9 ml/h). Local anesthetic requirements, maternal satisfaction, verbal pain scores, incidence of side effects, and outcome of labor were compared among groups.

Results
Patient demographics, labor characteristics, side effects, and Apgar scores were similar in each group. No significant differences were observed between groups in verbal pain scores during labor, number of supplemental boluses, or maternal satisfaction. A significantly greater overall total drug consumption with a 6-ml/h or a 9-ml/h background infusion (74 and 78 ml, respectively) was observed in comparison with PCEA without a background infusion (55 ml). A similar relation was observed for hourly use during both the first and the second stage of labor.

Conclusion
The results of this study suggest that the use of a background infusion with PCEA during labor leads to a greater consumption of anesthetic solution without improving comfort and satisfaction of parturients. Moreover, not using a background infusion does not provide an increased incidence of supplemental boluses (which might cause problems in a busy unit) and allows for a substantial reduction in the cost of analgesia.
Epidural Ropivacaine versus Epidural Morphine and the Catabolic Response to Colonic Surgery
Authors: Schricker Thomas , Wykes Linda , Eberhart Leopold , Lattermann Ralph , Carli Franco 
Published: March 2004

Background
The authors examined the hypothesis that epidural administration of local anesthetic, in contrast to epidural analgesia with morphine, inhibits postoperative protein oxidation during administration of glucose.

Methods
Fourteen patients were randomly assigned to undergo a 6-h stable isotope infusion study (3 h fasted, 3 h feeding with 4 mg.kg(-1).min(-1) glucose) on the second day after colorectal surgery using epidural analgesia with either continuous ropivacaine or intermittent morphine. Protein synthesis, breakdown and oxidation, and glucose production were measured by L-[L-13C]leucine and [6,6-2H2]glucose. Substrate oxidation rates were determined by indirect calorimetry. Plasma concentrations of metabolic substrates and hormones were also measured.

Results
Whole body protein breakdown, oxidation, synthesis, and glucose production in the fasted state were similar between the two groups. Glucose administration decreased protein breakdown (P = 0.01), protein synthesis (P = 0.001), and glucose production (P = 0.001) to the same extent in both groups, whereas protein oxidation was not significantly affected. The type of epidural analgesia did not significantly influence the circulating concentrations of metabolic substrates and hormones in the fasted or in the fed state. Carbohydrate oxidation rate in the ropivacaine group was greater than in patients receiving morphine (P = 0.04), regardless of whether glucose was infused.

Conclusion
Epidural analgesia achieved with ropivacaine or morphine does not suppress the catabolic response to surgery, either under fasting conditions or in the presence of an energy supply.
Influence of Sensory and Proprioceptive Impairment on the Development of Phantom Limb Syndrome during Regional Anesthesia
Authors: Paqueron Xavier , Leguen Morgan , Gentili Marc E. , Riou Bruno , Coriat Pierre , Willer Jean Claude 
Published: March 2004

Background
The relation between impairment of sensorimotor function and occurrence of phantom limb syndrome (PLS) during regional anesthesia has not been described. This study assessed the temporal relation between PLS and the progression of sensorimotor impairment during placement of a brachial plexus nerve block.

Methods
Fifty-two patients had their arm randomly placed either alongside their body (group A) or in 90 degrees abduction (group B) immediately after brachial plexus nerve block placement. Responses to pin prick, cold, heat, touch, proprioception, and voluntary movement were assessed every 5 min for 60 min. Meanwhile, patients described their perceptions of the size, shape, and position of their anesthetized limb.

Results
Phantom limb syndrome occurred 19 +/- 9 min after nerve block placement. Proprioception was impaired and abolished after 22 +/- 9 and 43 +/- 17 min, respectively (P < 0.05 vs. PLS onset). When PLS occurred, responses to pin prick, cold, heat, and proprioception were abolished in 96, 94, 87, and 4% of patients, respectively. Patients were more likely to feel their anesthetized limb in adduction and in abduction in groups A and B (P < 0.05 vs. group A), respectively. After PLS had become motionless, two stereotyped positions were identified: arm adduction, elbow flexion, hand over the abdomen (68% of group A patients) and arm abduction, elbow flexion, hand held close to the homolateral ear (48% of group B patients).

Conclusions
This study provides a better understanding of the determinants of PLS by showing that the final position of PLS is related both to the abolition of proprioception and the initial position of the anesthetized limb.
Tree species distributions and local habitat variation in the Amazon: large forest plot in eastern Ecuador
Authors: Valencia Renato , Foster Robin B. , Villa Gorky , Condit Richard , Svenning Jens‐Christian , Hernández Consuelo , Romoleroux Katya , Losos Elizabeth , Magård Else , Balslev Henrik 
Published: March 2004

Summary 1 We mapped and identified all trees ≥ 10 mm in diameter in 25 ha of lowland wet forest in Amazonian Ecuador, and found 1104 morphospecies among 152 353 individuals. The largest number of species was mid‐sized canopy trees with maximum height 10–20 m and understorey treelets with maximum height of 5–10 m. 2 Several species of understorey treelets in the genera Matisia and Rinorea dominated the forest numerically, while important canopy species were Iriartea deltoidea and Eschweilera coriacea. 3 We examined how species partition local topographic variation into niches, and how much this partitioning contributes to forest diversity. Evidence in favour of topographic niche‐partitioning was found: similarity in species composition between ridge and valley quadrats was lower than similarity between two valley (or two ridge) quadrats, and 25% of the species had large abundance differences between valley and ridge‐top. On the other hand, 25% of the species were generalists, with similar abundance on both valley and ridges, and half the species had only moderate abundance differences between valley and ridge. 4 Topographic niche‐partitioning was not finely grained. There were no more than three distinct vegetation zones: valley, mid‐slope, and upper‐ridge, and the latter two differed only slightly in species composition. 5 Similarity in species composition declined with distance even within a topographic habitat, to about the same degree as it declined between habitats. This suggests patchiness not related to topographic variation, and possibly due to dispersal limitation. 6 We conclude that partitioning of topographic niches does make a contribution to the α‐diversity of Amazonian trees, but only a minor one. It provides no explanation for the co‐occurrence of hundreds of topographic generalists, nor for the hundreds of species with similar life‐form appearing on a single ridge‐top.
Linear phase imaging using differential interference contrast microscopy
Authors: Arnison M. R. , Larkin K. G. , Sheppard C. J. R. , Smith N. I. , Cogswell C. J. 
Published: March 2004

SummaryWe propose an extension to Nomarski differential interference contrast microscopy that enables isotropic linear phase imaging. The method combines phase shifting, two directions of shear and Fourier‐space integration using a modified spiral phase transform. We simulated the method using a phantom object with spatially varying amplitude and phase. Simulated results show good agreement between the final phase image and the object phase, and demonstrate resistance to imaging noise.
A mathematical model of immunohistochemical preparations, which provides quantitative predictions
Authors: Holland T. , Holland H. 
Published: March 2004

SummaryA mathematical model of the reaction between primary antibody and epitope is described using the Law of Mass Action to define the reaction quantitatively. The model explains some of the peculiar properties of immunohistochemical preparations. It also predicts that antibody excess over epitope will not increase staining intensity for very avid primary antibodies. This property can be exploited to measure the amount of epitope in histological sections. The assumptions of the model are not specific to immunohistochemistry, and such reasoning should be widely applicable to tests based on highly avid detection systems with high amplification of the initial signal.
Quantitative phase‐amplitude microscopy. III. The effects of noise
Authors: Paganin D. , Barty A. , McMahon P. J. , Nugent K. A. 
Published: March 2004

SummaryWe explore the effect of noise on images obtained using quantitative phase‐amplitude microscopy – a new microscopy technique based on the determination of phase from the intensity evolution of propagating radiation. We compare the predictions with experimental results and also propose an approach that allows good‐quality quantitative phase retrieval to be obtained even for very noisy data.
Quantitative phase amplitude microscopy IV: imaging thick specimens
Authors: Bellair C. J. , Curl C. L. , Allman B. E. , Harris P. J. , Roberts A. , Delbridge L. M. D. , Nugent K. A. 
Published: March 2004

SummaryThe ability to image phase distributions with high spatial resolution is a key capability of microscopy systems. Consequently, the development and use of phase microscopy has been an important aspect of microscopy research and development. Most phase microscopy is based on a form of interference. Some phase imaging techniques, such as differential interference microscopy or phase microscopy, have a low coherence requirement, which enables high‐resolution imaging but in effect prevents the acquisition of quantitative phase information. These techniques are therefore used mainly for phase visualization. On the other hand, interference microscopy and holography are able to yield quantitative phase measurements but cannot offer the highest resolution. A new approach to phase microscopy, quantitative phase‐amplitude microscopy (QPAM) has recently been proposed that relies on observing the manner in which intensity images change with small defocuses and using these intensity changes to recover the phase. The method is easily understood when an object is thin, meaning its thickness is much less than the depth of field of the imaging system. However, in practice, objects will not often be thin, leading to the question of what precisely is being measured when QPAM is applied to a thick object. The optical transfer function formalism previously developed uses three‐dimensional (3D) optical transfer functions under the Born approximation. In this paper we use the 3D optical transfer function approach of Streibl not for the analysis of 3D imaging methods, such as tomography, but rather for the problem of analysing 2D phase images of thick objects. We go on to test the theoretical predictions experimentally. The two are found to be in excellent agreement and we show that the 3D imaging properties of QPAM can be reliably predicted using the optical transfer function formalism.
Application of transmission electron microscopes to nanometre‐sized fabrication by means of electron beam‐induced deposition
Authors: Shimojo M. , Mitsuishi K. , Tanaka M. , Han M. , Furuya K. 
Published: March 2004

SummaryElectron beam‐induced deposition was carried out using a scanning transmission electron microscope with a field emission gun to fabricate nanometre‐sized structures. A small amount of a metal–organic gas was introduced near the substrate in the microscope chamber, and focused electron beams were irradiated. Two‐ and three‐dimensional structures were fabricated by scanning the beam position. The minimum line width of the freestanding structures was 8 nm at a constant gas flux used. This line width of 8 nm is considered to be achieved by employing a high accelerating voltage, which leads to a small probe size, and the optimum scanning speed.
Comparison of conventional and microwave‐assisted processing of mouse retinas for transmission electron microscopy
Authors: Wendt K. D. , Jensen C. A. , Tindall R. , Katz M. L. 
Published: March 2004

SummaryConventional fixation and processing of mammalian retinal tissues for transmission electron microscopic (TEM) examination is slow and produces ultrastructural artefacts in the photoreceptor cell layer. Among these artefacts are gaps between photoreceptor outer segment disc membranes and between photoreceptor cells in the region of the retina where the cell nuclei are located. A study was undertaken to determine whether a much more rapid microwave‐assisted fixation and processing protocol would have an effect on the quality of ultrastructural preservation of the retina, particularly on the photoreceptor cell artefacts. The overall ultrastructural preservation of the retina was similar for the conventional and microwave‐assisted techniques. However, the magnitudes of the photoreceptor artefacts were significantly reduced when microwave irradiation was used during primary fixation and processing. It is clear that, at least for the retina, employing microwave irradiation during specimen preparation for TEM results in superior ultrastructural preservation with a substantial reduction in the time required for sample preparation.
Phase separation in molecular layers of macromolecules at the champagne–air interface
Authors: Peron N. , Meunier J. , Cagna A. , Valade M. , Douillard R. 
Published: March 2004

SummaryBubble and foam stability, which are essential for the hallmark of champagne, rely on the concentration of amphiphilic macromolecules originating from the grape, which form molecular layers at the interface between champagne and gas. Ellipsometry and Brewster angle microscopy experiments were conducted at the air–champagne interface to analyse the lateral organization of the layers of macromolecules. Several kinds of phase separations – leading in some cases to two‐dimensional foams – were identified. At the beginning of layer formation, condensed domains develop at the expense of dilute domains. Thereafter, phase separations occur within the condensed domains. These findings may allow advances in the implementation of methods predicting bubble and foam stability of champagnes.