[Intravenous administration of lidocaine for perioperative analgesia. Review and recommendations for practical usage]. / Intravenös verabreichtes Lidocain zur perioperativen Schmerztherapie. Übersicht und praktische Handlungsempfehlungen.

Lidocaine is commonly used for regional anesthesia and nerve blocks. However, recent clinical studies demonstrated that intravenous perioperative administration of lidocaine can lead to better postoperative analgesia, reduced opioid consumption and improved intestinal motility. It can therefore be used as an alternative when epidural analgesia is contraindicated, not possible or not feasible. Apart from the sodium channel blocking effects relevant for regional anesthesia, lidocaine also has anti-inflammatory properties. Lidocaine can obviously inhibit the priming of resting neutrophilic granulocytes, which, simplified, may reduce the liberation of superoxide anions, a common pathway of inflammation after multiple forms of tissue trauma. At the authors' institutions intravenous lidocaine is primarily used for postoperative pain relief following abdominal surgery and is given as a bolus dose of 1.5-2.0 mg/kg body weight (BW) injected over 5 min followed by an infusion of 1.5 mg/kg BW/h intraoperatively and 1.33 mg/kg BW/h postoperatively in the recovery room or in the intensive care unit (ICU). The lidocaine infusion is stopped in the recovery room 30 min before discharge or in the ICU at the latest after 24 h. Lidocaine is not used on normal wards. This overview summarizes the current evidence for the intravenous administration of lidocaine for patients undergoing different types of surgery and gives practical advice for its use.

Imaging odor coding and synaptic plasticity in the mammalian brain with a genetically-encoded probe.

We have used the genetically-encoded fluorescent exocytosis indicator synaptopHluorin (spH), expressed selectively in mouse olfactory receptor neurons, to image odor representations at the input to the olfactory bulb. The olfactory bulb is a powerful system for in vivo fluorescence imaging because its inputs are segregated into receptor-specific functional units (glomeruli) that are optically accessible and receive massively convergent input from sensory neurons. In a line of transgenic mice expressing spH under the control of a receptor neuron-specific promoter (OMP), odorant-evoked patterns of receptor neuron input to approximately 10% of the olfactory bulb can be imaged with excellent spatial resolution and sensitivity during single brief odorant presentations. Odor representations are similar across mice and can be imaged repeatedly in the same animal for months. In olfactory bulb slices from OP-spH mice, shock-evoked spH signals are rapid and linear reporters of transmitter release, although control for changes in extracellular pH is critical for proper interpretation of the spH signals. These features have allowed us to characterize the functional organization and mechanisms of presynaptic modulation of transmitter release at the first olfactory synapse. The capacity for long-term chronic imaging permits the direct visualization of the function regeneration and remapping of input to the olfactory bulb after lesions of the nasal epithelium.

An information-theoretic approach to estimating ultrasound backscatter characteristics.

Analysis of backscatter in the ultrasound echo envelope, in conjunction with ultrasound B-scans, can provide important information for tissue characterization and pathology diagnosis. Statistical models have often proven useful in modeling backscatter. In this paper, an innovative approach to backscatter analysis based on generalized entropies and neural function approximation is presented. Entropy measures are shown to provide accurate estimates of scatterer density, regularity, and SNR of the amplitude distribution. Specific scattering distributions need not be assumed. Experimental results on ground truth envelopes show that generalized entropies can be used to accurately estimate backscatter properties.

Representation of odorants by receptor neuron input to the mouse olfactory bulb.

To visualize odorant representations by receptor neuron input to the mouse olfactory bulb, we loaded receptor neurons with calcium-sensitive dye and imaged odorant-evoked responses from their axon terminals. Fluorescence increases reflected activation of receptor neuron populations converging onto individual glomeruli. We report several findings. First, five glomeruli were identifiable across animals based on their location and odorant responsiveness; all five showed complex response specificities. Second, maps of input were chemotopically organized at near-threshold concentrations but, at moderate concentrations, involved many widely distributed glomeruli. Third, the dynamic range of input to a glomerulus was greater than that reported for individual receptor neurons. Finally, odorant activation slopes could differ across glomeruli, and for different odorants activating the same glomerulus. These results imply a high degree of complexity in odorant representations at the level of olfactory bulb input.

Patch-clamp analysis of voltage-activated and chemically activated currents in the vomeronasal organ of Sternotherus odoratus (stinkpot/musk turtle).

The electrophysiological basis of chemical communication in the specialized olfactory division of the vomeronasal (VN) organ is poorly understood. In total, 198 patch-clamp recordings were made from 42 animals (Sternotherus odoratus, the stinkpot/musk turtle) to study the electrically and chemically activated properties of VN neurons. The introduction of tetramethylrhodamine-conjugated dextran into the VN orifice permitted good visualization of the vomeronasal neural epithelium prior to dissociating it into single neurons. Basic electrical properties of the neurons were measured (resting potential, -54.5 +/- 2.7 mV, N=11; input resistance, 6.7 +/- 1.4 G Omega, N=25; capacitance, 4.2 +/- 0.3 pF, N=22; means +/- S.E.M.). The voltage-gated K(+) current inactivation rate was significantly slower in VN neurons from males than in those from females, and K(+) currents in males were less sensitive (greater K(i)) to tetraethylammonium. Vomeronasal neurons were held at a holding potential of -60 mV and tested for their response to five natural chemicals, female urine, male urine, female musk, male musk and catfish extract. Of the 90 VN neurons tested, 33 (34 %) responded to at least one of the five compounds. The peak amplitude of chemically evoked currents ranged from 4 to 180 pA, with two-thirds of responses less than 25 pA. Urine-evoked currents were of either polarity, whereas musk and catfish extract always elicited only inward currents. Urine applied to neurons harvested from female animals evoked currents that were 2-3 times larger than those elicited from male neurons. Musk-evoked inward currents were three times the magnitude of urine- or catfish-extract-evoked inward currents. The calculated breadth of responsiveness for neurons presented with this array of five chemicals indicated that the mean response spectrum of the VN neurons is narrow (H metric 0.11). This patch-clamp study indicates that VN neurons exhibit sexual dimorphism in function and specificity in response to complex natural chemicals.iol

A computer analysis of reflex eyelid motion in normal subjects and in facial neuropathy.

OBJECTIVE: To demonstrate how computerized eyelid motion analysis can quantify the human reflex blink. DESIGN: Seventeen normal subjects and 10 patients with unilateral facial nerve paralysis were analyzed. BACKGROUND: Eyelid closure is currently evaluated by systems primarily designed to assess lower/midfacial movements. The methods are subjective, difficult to reproduce, and measure only volitional closure. Reflex closure is responsible for eye hydration, and its evaluation demands dynamic analysis. METHODS: A 60Hz video camera incorporated into a helmet was used to analyze blinking. Reflective markers on the forehead and eyelids allowed for the dynamic measurement of the reflex blink. Eyelid displacement, velocity and acceleration were calculated. The degree of synchrony between bilateral blinks was also determined. RESULTS: This study demonstrates that video motion analysis can describe normal and altered eyelid motions in a quantifiable manner. CONCLUSIONS: To our knowledge, this is the first study to measure dynamic reflex blinks. Eyelid closure may now be evaluated in kinematic terms. This technique could increase understanding of eyelid motion and permit more accurate evaluation of eyelid function. Dynamic eyelid evaluation has immediate applications in the treatment of facial palsy affecting the reflex blink. Relevance No method has been developed that objectively quantifies dynamic eyelid closure. Methods currently in use evaluate only volitional eyelid closure, and are based on direct and indirect observer assessments. These methods are subjective and are incapable of analyzing dynamic eyelid movements, which are critical to maintenance of corneal hydration and comfort. A system that quantifies eyelid kinematics can provide a functional analysis of blink disorders and an objective evaluation of their treatment(s).

Wavelet-based noise removal for biomechanical signals: a comparative study.

The purpose of this paper is to present wavelet-based noise removal (WBNR) techniques to remove noise from biomechanical acceleration signals obtained from numerical differentiation of displacement data. Manual and semiautomatic methods were used to determine thresholds for both orthogonal and biorthogonal filters. This study also compares the performance of WBNR approaches with four automatic conventional noise removal techniques used in biomechanics. The conclusion of this work is that WBNR techniques are very effective in removing noise from differentiated signals with sharp transients while leaving these transients intact. For biomechanical signals with certain characteristics, WBNR techniques perform better than conventional methods, as indicated by quantitative merit measures.

Imaging membrane potential with voltage-sensitive dyes.

Membrane potential can be measured optically using a variety of molecular probes. These measurements can be useful in studying function at the level of an individual cell, for determining how groups of neurons generate a behavior, and for studying the correlated behavior of populations of neurons. Examples of the three kinds of measurements are presented. The signals obtained from these measurements are generally small. Methodological considerations necessary to optimize the resulting signal-to-noise ratio are discussed.

Odors elicit three different oscillations in the turtle olfactory bulb.

We measured the spatiotemporal aspects of the odor-induced population response in the turtle olfactory bulb using a voltage-sensitive dye, RH414, and a 464-element photodiode array. In contrast with previous studies of population activity using local field potential recordings, we distinguished four signals in the response. The one called DC covered almost the entire area of the olfactory bulb; in addition, three oscillations, named rostral, middle, and caudal according to their locations, occurred over broad regions of the bulb. In a typical odor-induced response, the DC signal appeared almost immediately after the start of the stimulus, followed by the middle oscillation, the rostral oscillation, and last, the caudal oscillation. The initial frequencies of the three oscillations were 14.1, 13.0, and 6.6 Hz, respectively. When the rostral and caudal oscillations occurred together, their frequencies differed by a factor of 1.99 +/- 0.01. The following evidence suggests that the four signals are functionally independent: (1) in different animals some signals could be easily detected whereas others were undetectable; (2) the four signals had different latencies and frequencies; (3) the signals occurred in different locations and propagated in different directions; (4) the signals responded differently to changes in odor concentration; (5) the signals had different shapes; and (6) the rostral and caudal signals added in a simple, linear manner in regions where the location of the two signals overlapped. However, the finding that the frequency of the rostral oscillation is precisely two times that of the caudal oscillation suggests a significant relationship between the two. The location of the caudal oscillation in the bulb changed from cycle to cycle, implying that different groups of neurons are active in different cycles. This result is consistent with the earlier findings in the olfactory system of the locust (). Our results suggest an additional complexity of parallel processing of olfactory input by multiple functional population domains.

A deficient anterior cruciate ligament does not lead to quadriceps avoidance gait.

Without an intact anterior cruciate ligament (ACL) to resist anterior tibial translation, it is commonly believed that ACL-deficient patients employ alterations in walking. Although there is no consensus in the literature about the specific kinematic and kinetic adaptations in these patients with ACL tears, the gait adaptation of quadriceps avoidance is perhaps the one most popularized. The purpose of our study was to determine whether quadriceps avoidance is common in patients with ACL-deficiency. We used a video-based motion analysis system and surface electromyography (EMG) to study 18 patients with ACL-deficiency. All patients demonstrated an internal knee extension moment during early mid-stance (similar to normal subjects). Quadriceps EMG activity was noted throughout most of stance. No patients demonstrated an internal knee flexion moment, a decreased internal knee extension moment or a decreased duration of quadriceps EMG activity during stance. The findings of this study would suggest that quadriceps avoidance as a gait adaptation in ACL-deficient patients may be less common than previously reported.

A demonstration of validity of 3-D video motion analysis method for measuring finger flexion and extension.

This study demonstrates the validity of using 3-D video motion analysis to measure hand motion. Several researchers have devised ingenious methods to study normal and abnormal hand movements. Although very helpful, these earlier studies are static representations of a dynamic phenomenon. Despite the many studies of hand motion using scientifically impeccable techniques, little is known about digital motion, and there are still few researchers investigating dynamic three-dimensional motion of the hand. Results from a three-camera video motion analysis system were compared to those from the "gold standard", 2-D lateral view fluoroscopy. We used these two methods to record hand motion simultaneously during unrestricted flexion and extension of the index finger of the dominant hand in 6 neurologically normal, healthy volunteers. After collection and post-processing, the waveforms of the PIP, DIP and MCP joint angles were compared using the adjusted coefficient of multiple determination (R2(a), or CMD). The mean CMD values for the MCP, PIP and DIP joint angle waveforms were 0.96, 0.98 and 0.94, respectively, suggesting a close similarity between motion of comparable joints analyzed by the 2-D and 3-D methods. This shows that the method of 3-D motion analysis is capable of accurately quantifying digital joint motion. It is anticipated that 3-D motion analysis, in addition to being used as a research tool, will also have clinical applications such as surgical planning in neuromuscular disorders and the documentation of abnormal motion in many other pathological hand conditions.

Presynaptic inhibition of primary olfactory afferents mediated by different mechanisms in lobster and turtle.

Presynaptic regulation of transmission at the first olfactory synapse was investigated by selectively imaging axon terminals of receptor neurons in the lobster olfactory lobe and turtle olfactory bulb. In both species, action potential propagation into axon terminals after olfactory nerve stimulation was measured using voltage-sensitive dyes. In addition, in the turtle, calcium influx into terminals was measured by selectively labeling receptor neurons with dextran-conjugated calcium indicator dyes. In the lobster, application of the inhibitory transmitters GABA or histamine suppressed action potentials in the terminals. The suppression was blocked by picrotoxin and cimetidine, respective antagonists to lobster GABA and histamine receptors. These results suggest that previously characterized GABA and histaminergic interneurons regulate olfactory input by suppressing action potential propagation into axon terminals of olfactory afferents. In contrast, in the turtle olfactory bulb, neither GABA nor dopamine had any effect on receptor cell action potentials as measured with voltage-sensitive dyes. However, calcium influx into axon terminals was reduced by the GABA(B) agonist baclofen and the dopamine D(2) agonist quinpirole, and paired-pulse suppression of calcium influx was reduced by the GABA(B) antagonist saclofen. These results indicate that in the turtle, GABA and dopamine mediate presynaptic inhibition not by affecting action potentials directly, as in the lobster, but by reducing calcium influx via GABA(B) and dopamine D(2) receptors. Thus, although mediated by different cellular mechanisms, presynaptic regulation of olfactory input to the CNS, via dual synaptic pathways, is a feature common to vertebrates and invertebrates. This inhibition may be important in the processing of olfactory information.

The motion path of the digits.

This study investigates whether the path taken by the fingertips of the human hand during unrestricted flexion and extension follows a precise mathematical pattern: an equiangular spiral. Eight normal subjects participated in the study. Subjects performed numerous flexion and extension trials at a random speed. Motion was recorded by a 6-camera, 3-dimensional motion analysis system with 24 retroreflective markers affixed to the dominant hand at predetermined locations. Four hundred eighty flexion-extension arcs were analyzed. We used the coefficient of multiple determination to compare the flexion and extension motion arc of each finger to an equiangular spiral curve derived mathematically. Our results indicate that the path of the hand during flexion and extension closely follows the path of an equiangular spiral with the coefficient of multiple determination values consistently above 0.95.

Presynaptic afferent inhibition of lobster olfactory receptor cells: reduced action-potential propagation into axon terminals.

Action-potential propagation into the axon terminals of olfactory receptor cells was measured with the use of voltage-sensitive dye imaging in the isolated spiny lobster brain. Conditioning shocks to the olfactory nerve, known to cause long-lasting suppression of olfactory lobe neurons, allowed the selective imaging of activity in receptor cell axon terminals. In normal saline the optical signal from axon terminals evoked by a test stimulus was brief (40 ms) and small in amplitude. In the presence of low-Ca2+/high-Mg2+ saline designed to reduce synaptic transmission, the test response was unchanged in time course but increased significantly in amplitude (57 +/- 16%, means +/- SE). This increase suggests that propagation into receptor cell axon terminals is normally suppressed after a conditioning shock; this suppression is presumably synaptically mediated. Thus our results show that presynaptic inhibition occurs at the first synapse in the olfactory pathway and that the inhibition is mediated, at least in part, via suppression of action-potential propagation into the presynaptic terminal.

The initiation and sequence of digital joint motion. A three-dimensional motion analysis.

We studied the initiation and sequence of digital joint motion during unrestricted flexion and extension using a 3-D motion analysis of all fingers moving simultaneously. Our results showed that motion started in a single joint in 83%, of flexion and 80%, of extension cycles. The DIP joint initiated flexion and extension in the index, middle, and ring fingers, but in the little finger, flexion started in the PIP joint, and extension in the MP joint. The two most frequent sequences of joint movement during flexion of the three radial fingers were DIP-PIP-MP and PIP-DIP-MP. The two most frequent sequences during extension of the three radial fingers were DIP-MP-PIP followed by DIP-MP/PIP. In the little finger, however, the most frequent sequences during flexion were PIP-DIP-MP followed by DIP-PIP-MP and during extension, DIP-MP/PIP followed by PIP/DIP-MP.

Ionotropic GABA receptor from lobster olfactory projection neurons.

This study reports an ionotropic GABA (gamma-aminobutyric acid) receptor in projection neurons acutely dissociated from the olfactory lobe of the brain of the spiny lobster and analyzed by whole cell and cell-free patch-clamp recording. GABA evokes a macroscopic current in the cells that is linear from -100 to + 100 mV, reverses at the imposed chloride equilibrium potential, has a permeability sequence of Cl- > acetate > bicarbonate > phosphate > propionate and SCN- > Br- > I- > Cl- > F-, and is reversibly blocked by the Cl channel blocker picrotoxin but not tert-butylbicyclophosphorothionate (TBPS). The current is bicuculline insensitive and activated by muscimol, isoguvacine, cis-4-aminocrotonic acid (CACA), and trans-aminocrotonic acid (TACA), as well as by the GABA(C)-receptor antagonists 4,5,6,7-tetrahydroisoxazolo [5,4,-c]pyridin-3-ol (THIP), 3-amino-1-propanesulfonic acid (3-APS), and imidazole-4-acetic acid (I-4AA), but not the GABA(B)-receptor agonists baclofen and 3-aminopropylphosphonic acid (3-APA). Agonist potency for the receptor is TACA > muscimol > GABA > I-4AA > isoguvacine > 3-APS > CACA > THIP. Unitary chloride currents in cell-free, outside-out patches from the cells share enough of these pharmacological properties to indicate that the channel underlies the macroscopic current. The receptor mediates an inhibitory current in the cells in vivo. The receptor is similar, if not identical, to one from neurons cultured from the thoracic ganglia of the clawed lobster. The more extensive pharmacological characterization of the receptor reported here indicates that this lobster CNS receptor is pharmacologically distinct from previously characterized ionotropic GABA receptors.

Local interneurons define functionally distinct regions within lobster olfactory glomeruli

Whole-cell recording coupled with biocytin injection revealed four types of interneurons intrinsic to the olfactory lobe (OL) of the spiny lobster Panulirus argus. Each type of neuron had a distinct pattern of arborization within the three anatomically defined regions of OL glomeruli (cap, subcap and base). Type I interneurons innervated all three regions, while types II, III and IV branched only in the cap, subcap and base, respectively. Type I interneurons responded to electrical stimulation of the antennular (olfactory) nerve with a burst of 1­20 action potentials and a 1­10 s depolarization. Type II (cap) interneurons responded to the same input with a burst of 1­3 action potentials followed by a shorter hyperpolarization. Type III (subcap) interneurons responded with a burst of 1­6 action potentials followed by a delayed, 0.5­4 s depolarization. Type IV (base) interneurons responded with a brief depolarization or a burst of 1­3 action potentials followed by a 1 s hyperpolarization. The regionalized arborization and the different response properties of the type II, III and IV interneurons strongly imply that lobster olfactory glomeruli contain functionally distinct regions, a feature that should be useful in understanding the multiple synaptic pathways involved in processing olfactory input.

Enhancement of gustatory nerve fibers to NaCl and formation of ion channels by commercial novobiocin.

Single fibers of the rat chorda tympani nerve were used to study the mechanism of action of the antibiotic novobiocin on salt taste transduction. In the rat, novobiocin selectively enhanced the responses of sodium-specific and amiloride-sensitive chorda tympani nerve fibers (N type) without affecting more broadly responsive cation-sensitive and amiloride-insensitive fibers (E type). In the presence of amiloride, novobiocin was ineffective at enhancing the response of N-type fibers toward sodium chloride. Novobiocin also increased the conductance of bilayers formed from neutral lipids by forming nonrectifying ion channels with low conductance (approximately 7 pS in 110 mM NaCl), long open times (several seconds and longer), and high cation selectivity. Amiloride did not alter either the conductance or kinetics of these novobiocin channels. These observations suggest that even though novobiocin is able to form cation channels in lipid bilayers, and possibly in cell membranes as well, its action on the salt-taste response is through modulation of existing amiloride-sensitive sodium channels.