bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency-Dependent Modes of Synaptic Vesicle Endocytosis and Exocytosis at Adult Mouse Neuromuscular Junctions
Authors: Maeno-Hikichi Yuka , Polo-Parada Luis , Kastanenka Ksenia V. , Landmesser Lynn T.
Published: January 2011

During locomotion, adult rodent lumbar motoneurons fire in high-frequency (80–100 Hz) 1–2 s bursts every several seconds, releasing between 10,000 and 20,000 vesicles per burst. The estimated total vesicle pool size indicates that all vesicles would be used within 30 s; thus, a mechanism for rapid endocytosis and vesicle recycling is necessary to maintain effective transmission and motor behavior. However, whether such rapid recycling exists at mouse neuromuscular junctions (NMJs) or how it is regulated has been unclear. Here, we show that much less FM1-43 dye is lost per stimulus with 100 Hz stimulation than with 10 Hz stimulation even when the same number of vesicles undergo exocytosis. Electrophysiological data using folimycin show this lesser amount of dye loss is caused in part by the rapid reuse of vesicles. We showed previously that a myosin light chain kinase (MLCK)–myosin II pathway was required for effective transmission at 100 Hz. Here, we confirm the activation of MLCK, based on increased nerve terminal phospho-MLC immunostaining, with 100 Hz but not with 10 Hz stimulation. We further demonstrate that activation of MLCK, by increased extracellular Ca2+, by PKC (protein kinase C) activation, or by a MLCK agonist peptide, reduces the amount of dye lost even with 10 Hz stimulation. MLCK activation at 10 Hz also resulted in more vesicles being rapidly reused. Thus, MLCK activation by 100 Hz stimulation switches the mechanism of vesicle cycling to a rapid-reuse mode and is required to sustain effective transmission in adult mouse NMJs.
Functional Magnetic Resonance Imaging Blood Oxygenation Level-Dependent Signal and Magnetoencephalography Evoked Responses Yield Different Neural Functionality in Reading
Authors: Vartiainen Johanna , Liljeström Mia , Koskinen Miika , Renvall Hanna , Salmelin Riitta
Published: January 2011

It is often implicitly assumed that the neural activation patterns revealed by hemodynamic methods, such as functional magnetic resonance imaging (fMRI), and electrophysiological methods, such as magnetoencephalography (MEG) and electroencephalography (EEG), are comparable. In early sensory processing that seems to be the case, but the assumption may not be correct in high-level cognitive tasks. For example, MEG and fMRI literature of single-word reading suggests differences in cortical activation, but direct comparisons are lacking. Here, while the same human participants performed the same reading task, analysis of MEG evoked responses and fMRI blood oxygenation level-dependent (BOLD) signals revealed marked functional and spatial differences in several cortical areas outside the visual cortex. Divergent patterns of activation were observed in the frontal and temporal cortex, in accordance with previous separate MEG and fMRI studies of reading. Furthermore, opposite stimulus effects in the MEG and fMRI measures were detected in the left occipitotemporal cortex: MEG evoked responses were stronger to letter than symbol strings, whereas the fMRI BOLD signal was stronger to symbol than letter strings. The EEG recorded simultaneously during MEG and fMRI did not indicate neurophysiological differences that could explain the observed functional discrepancies between the MEG and fMRI results. Acknowledgment of the complementary nature of hemodynamic and electrophysiological measures, as reported here in a cognitive task using evoked response analysis in MEG and BOLD signal analysis in fMRI, represents an essential step toward an informed use of multimodal imaging that reaches beyond mere combination of location and timing of neural activation.
HMGB1 Acts on Microglia Mac1 to Mediate Chronic Neuroinflammation That Drives Progressive Neurodegeneration
Authors: Gao Hui-Ming , Zhou Hui , Zhang Feng , Wilson Belinda C. , Kam Wayneho , Hong Jau-Shyong
Published: January 2011

What drives the gradual degeneration of dopamine neurons in Parkinson's disease (PD), the second most common neurodegenerative disease, remains elusive. Here, we demonstrated, for the first time, that persistent neuroinflammation was indispensible for such a neurodegenerative process. 1-Methyl-4-phenylpyridinium, lipopolysaccharide (LPS), and rotenone, three toxins often used to create PD models, produced acute but nonprogressive neurotoxicity in neuron-enriched cultures. In the presence of microglia (brain immune cells), these toxins induced progressive dopaminergic neurodegeneration. More importantly, such neurodegeneration was prevented by removing activated microglia. Collectively, chronic neuroinflammation may be a driving force of progressive dopaminergic neurodegeneration. Conversely, ongoing neurodegeneration sustained microglial activation. Microglial activation persisted only in the presence of neuronal damage in LPS-treated neuron–glia cultures but not in LPS-treated mixed-glia cultures. Thus, activated microglia and damaged neurons formed a vicious cycle mediating chronic, progressive neurodegeneration. Mechanistic studies indicated that HMGB1 (high-mobility group box 1), released from inflamed microglia and/or degenerating neurons, bound to microglial Mac1 (macrophage antigen complex 1) and activated nuclear factor-κB pathway and NADPH oxidase to stimulate production of multiple inflammatory and neurotoxic factors. The treatment of microglia with HMGB1 led to membrane translocation of p47phox(a cytosolic subunit of NADPH oxidase) and consequent superoxide release, which required the presence of Mac1. Neutralization of HMGB1 and genetic ablation of Mac1 and gp91phox(the catalytic submit of NADPH oxidase) blocked the progressive neurodegeneration. Our findings indicated that HMGB1–Mac1–NADPH oxidase signaling axis bridged chronic neuroinflammation and progressive dopaminergic neurodegeneration, thus identifying a mechanistic basis for chronic PD progression.
Precision in Visual Working Memory Reaches a Stable Plateau When Individual Item Limits Are Exceeded
Authors: Anderson David E. , Vogel Edward K. , Awh Edward
Published: January 2011

Multiple studies have demonstrated that resolution in working memory (WM) declines as the number of stored items increases. Discrete-resource models predict that this decline should reach a stable plateau at relatively small set sizes because item limits prevent additional information from being encoded into WM at larger set sizes. By contrast, flexible-resource models predict that the monotonic declines in precision will continue indefinitely as set size increases and resources are distributed without any fixed item limit. In the present work, we found that WM resolution exhibited monotonic declines until set size reached three items, after which resolution achieved a clear asymptote. Moreover, analyses of individual differences showed a strong correlation between each observer's item limit and the set size at which WM resolution achieved asymptote. These behavioral observations were corroborated by measurements of contralateral delay activity (CDA), an event-related potential waveform that tracks the number of items maintained during the delay period. CDA activity rose monotonically and achieved asymptote at a set size that predicted individual WM capacity. Moreover, this neural measure of on-line storage also predicted the set size at which mnemonic resolution reached a stable plateau for each observer. Thus, independent behavioral and neural measures of WM capacity support a clear prediction of discrete-resource models. Precision in visual WM reaches asymptote when individual item limits are exceeded.
Adaptive Allocation of Vision under Competing Task Demands
Authors: Sims Chris R. , Jacobs Robert A. , Knill David C.
Published: January 2011

Human behavior in natural tasks consists of an intricately coordinated dance of cognitive, perceptual, and motor activities. Although much research has progressed in understanding the nature of cognitive, perceptual, or motor processing in isolation or in highly constrained settings, few studies have sought to examine how these systems are coordinated in the context of executing complex behavior. Previous research has suggested that, in the course of visually guided reaching movements, the eye and hand are yoked, or linked in a nonadaptive manner. In this work, we report an experiment that manipulated the demands that a task placed on the motor and visual systems, and then examined in detail the resulting changes in visuomotor coordination. We develop an ideal actor model that predicts the optimal coordination of vision and motor control in our task. On the basis of the predictions of our model, we demonstrate that human performance in our experiment reflects an adaptive response to the varying costs imposed by our experimental manipulations. Our results stand in contrast to previous theories that have assumed a fixed control mechanism for coordinating vision and motor control in reaching behavior.
Distinct Representations of a Perceptual Decision and the Associated Oculomotor Plan in the Monkey Lateral Intraparietal Area
Authors: Bennur Sharath , Gold Joshua I.
Published: January 2011

Perceptual decisions that are used to select particular actions can appear to be formed in an intentional framework, in which sensory evidence is converted directly into a plan to act. However, because the relationship between perceptual decision-making and action selection has been tested primarily under conditions in which the two could not be dissociated, it is not known whether this intentional framework plays a general role in forming perceptual decisions or only reflects certain task conditions. To dissociate decision and motor processing in the brain, we recorded from individual neurons in the lateral intraparietal area of monkeys performing a task that included a flexible association between a decision about the direction of random-dot motion and the direction of the appropriate eye-movement response. We targeted neurons that responded selectively in anticipation of a particular eye-movement response. We found that these neurons encoded the perceptual decision in a manner that was distinct from how they encoded the associated response. These decision-related signals were evident regardless of whether the appropriate decision–response association was indicated before, during, or after decision formation. The results suggest that perceptual decision-making and action selection are different brain processes that only appear to be inseparable under particular behavioral contexts.
Neural Basis of Superior Performance of Action Videogame Players in an Attention-Demanding Task
Authors: Mishra Jyoti , Zinni Marla , Bavelier Daphne , Hillyard Steven A.
Published: January 2011

Steady-state visual evoked potentials (SSVEPs) were recorded from action videogame players (VGPs) and from non-videogame players (NVGPs) during an attention-demanding task. Participants were presented with a multi-stimulus display consisting of rapid sequences of alphanumeric stimuli presented at rates of 8.6/12 Hz in the left/right peripheral visual fields, along with a central square at fixation flashing at 5.5 Hz and a letter sequence flashing at 15 Hz at an upper central location. Subjects were cued to attend to one of the peripheral or central stimulus sequences and detect occasional targets. Consistent with previous behavioral studies, VGPs detected targets with greater speed and accuracy than NVGPs. This behavioral advantage was associated with an increased suppression of SSVEP amplitudes to unattended peripheral sequences in VGPs relative to NVGPs, whereas the magnitude of the attended SSVEPs was equivalent in the two groups. Group differences were also observed in the event-related potentials to targets in the alphanumeric sequences, with the target-elicited P300 component being of larger amplitude in VGPS than NVGPs. These electrophysiological findings suggest that the superior target detection capabilities of the VGPs are attributable, at least in part, to enhanced suppression of distracting irrelevant information and more effective perceptual decision processes.
Calcium-Independent Inhibitory G-Protein Signaling Induces Persistent Presynaptic Muting of Hippocampal Synapses
Authors: Crawford Devon C. , Chang Chun Yun , Hyrc Krzysztof L. , Mennerick Steven
Published: January 2011

Adaptive forms of synaptic plasticity that reduce excitatory synaptic transmission in response to prolonged increases in neuronal activity may prevent runaway positive feedback in neuronal circuits. In hippocampal neurons, for example, glutamatergic presynaptic terminals are selectively silenced, creating “mute” synapses, after periods of increased neuronal activity or sustained depolarization. Previous work suggests that cAMP-dependent and proteasome-dependent mechanisms participate in silencing induction by depolarization, but upstream activators are unknown. We, therefore, tested the role of calcium and G-protein signaling in silencing induction in cultured hippocampal neurons. We found that silencing induction by depolarization was not dependent on rises in intracellular calcium, from either extracellular or intracellular sources. Silencing was, however, pertussis toxin sensitive, which suggests that inhibitory G-proteins are recruited. Surprisingly, blocking four common inhibitory G-protein-coupled receptors (GPCRs) (adenosine A1receptors, GABABreceptors, metabotropic glutamate receptors, and CB1cannabinoid receptors) and one ionotropic receptor with metabotropic properties (kainate receptors) failed to prevent depolarization-induced silencing. Activating a subset of these GPCRs (A1and GABAB) with agonist application induced silencing, however, which supports the hypothesis that G-protein activation is a critical step in silencing. Overall, our results suggest that depolarization activates silencing through an atypical GPCR or through receptor-independent G-protein activation. GPCR agonist-induced silencing exhibited dependence on the ubiquitin-proteasome system, as was shown previously for depolarization-induced silencing, implicating the degradation of vital synaptic proteins in silencing by GPCR activation. These data suggest that presynaptic muting in hippocampal neurons uses a G-protein-dependent but calcium-independent mechanism to depress presynaptic vesicle release.
The Suppressive Effect of an Intra-Prefrontal Cortical Infusion of BDNF on Cocaine-Seeking Is Trk Receptor and Extracellular Signal-Regulated Protein Kinase Mitogen-Activated Protein Kinase Dependent
Authors: Whitfield Timothy W. , Shi Xiangdang , Sun Wei-Lun , McGinty Jacqueline F.
Published: January 2011

Cocaine-mediated neuroadaptations in the prefrontal cortical-nucleus accumbens pathway underlie drug-seeking in animals with a cocaine self-administration (SA) history. Neuroplasticity in the cortico-accumbens pathway is regulated, in part, by the expression and availability of neurotrophic factors, such as BDNF. We have previously demonstrated that infusion of BDNF into the dorsomedial prefrontal cortex (dmPFC) immediately after the last of 10 cocaine SA sessions attenuates contextual, cue- and cocaine prime-induced reinstatement of cocaine-seeking (Berglind et al., 2007) and normalizes cocaine-induced disruption of glutamatergic transmission in the nucleus accumbens (Berglind et al., 2009). In the present study, the suppressive effect of intra-dmPFC BDNF on cocaine-seeking is shown to depend on Trk receptor-mediated activation of extracellular signal-regulated kinase (ERK) signaling in the dmPFC. The tyrosine kinase inhibitor, K252a, and the mitogen-activated protein/extracellular signal-regulated kinase kinase inhibitor, U0126 (1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene), prevented BDNF's suppressive effects on cocaine-seeking. Vehicle-infused rats with a cocaine SA history showed significant decreases in ERK and cyclic AMP response element binding protein (CREB), but not Akt, phosphorylation after the final cocaine SA session that were reversed by intra-dmPFC BDNF. Additionally, BDNF's ability to normalize cocaine-mediated decreases in ERK and CREB phosphorylation was blocked by U0126, demonstrating that ERK/MAPK activation mediated the behavioral effects. This study elucidates a mechanism whereby BDNF/TrkB (tropomyosin receptor kinase B) activates ERK-regulated CREB phosphorylation in the dmPFC to counteract the neuroadaptations induced by cocaine SA and subsequent relapse to cocaine-seeking.
The GABAAReceptor α+β− Interface: A Novel Target for Subtype Selective Drugs
Authors: Ramerstorfer Joachim , Furtmüller Roman , Sarto-Jackson Isabella , Varagic Zdravko , Sieghart Werner , Ernst Margot
Published: January 2011

GABAAreceptors mediate the action of many clinically important drugs interacting with different binding sites. For some potential binding sites, no interacting drugs have yet been identified. Here, we established a steric hindrance procedure for the identification of drugs acting at the extracellular α1+β3− interface, which is homologous to the benzodiazepine binding site at the α1+γ2− interface. On screening of >100 benzodiazepine site ligands, the anxiolytic pyrazoloquinoline 2-p-methoxyphenylpyrazolo[4,3−c]quinolin-3(5H)-one (CGS 9895) was able to enhance GABA-induced currents at α1β3 receptors from rat. CGS 9895 acts as an antagonist at the benzodiazepine binding site at nanomolar concentrations, but enhances GABA-induced currents via a different site present at α1β3γ2 and α1β3 receptors. By mutating pocket-forming amino acid residues at the α1+ and the β3− side to cysteines, we demonstrated that covalent labeling of these cysteines by the methanethiosulfonate ethylamine reagent MTSEA-biotin was able to inhibit the effect of CGS 9895. The inhibition was not caused by a general inactivation of GABAAreceptors, because the GABA-enhancing effect of ROD 188 or the steroid α-tetrahydrodeoxycorticosterone was not influenced by MTSEA-biotin. Other experiments indicated that the CGS 9895 effect was dependent on the α and β subunit types forming the interface. CGS 9895 thus represents the first prototype of drugs mediating benzodiazepine-like modulatory effects via the α+β− interface of GABAAreceptors. Since such binding sites are present at αβ, αβγ, and αβδ receptors, such drugs will have a much broader action than benzodiazepines and might become clinical important for the treatment of epilepsy.
Genetically Induced Adult Oligodendrocyte Cell Death Is Associated with Poor Myelin Clearance, Reduced Remyelination, and Axonal Damage
Authors: Pohl Hartmut B. F. , Porcheri Cristina , Mueggler Thomas , Bachmann Lukas C. , Martino Gianvito , Riethmacher Dieter , Franklin Robin J. M. , Rudin Markus , Suter Ueli
Published: January 2011

Loss of oligodendrocytes is a feature of many demyelinating diseases including multiple sclerosis. Here, we have established and characterized a novel model of genetically induced adult oligodendrocyte death. Specific primary loss of adult oligodendrocytes leads to a well defined and highly reproducible course of disease development that can be followed longitudinally by magnetic resonance imaging. Histological and ultrastructural analyses revealed progressive myelin vacuolation, in parallel to disease development that includes motor deficits, tremor, and ataxia. Myelin damage and clearance were associated with induction of oligodendrocyte precursor cell proliferation, albeit with some regional differences. Remyelination was present in the mildly affected corpus callosum. Consequences of acutely induced cell death of adult oligodendrocytes included secondary axonal damage. Microglia were activated in affected areas but without significant influx of B-cells, T-helper cells, or T-cytotoxic cells. Analysis of the model on aRAG-1(recombination activating gene-1)-deficient background, lacking functional lymphocytes, did not change the observed disease and pathology compared with immune-competent mice. We conclude that this model provides the opportunity to study the consequences of adult oligodendrocyte death in the absence of primary axonal injury and reactive cells of the adaptive immune system. Our results indicate that if the blood–brain barrier is not disrupted, myelin debris is not removed efficiently, remyelination is impaired, and axonal integrity is compromised, likely as the result of myelin detachment. This model will allow the evaluation of strategies aimed at improving remyelination to foster axon protection.
New Zealand and the American Civil War
Authors: Thorp Daniel B.
Published: January 2011

By 1861 residents of New Zealand had been dealing with Americans for years, and they recognized that the United States was already an important power on the Pacific Rim. Thus, when the American Civil War broke out, people in New Zealand paid careful attention. Newspapers, private papers, and official records reveal the war's effect in New Zealand. Although New Zealanders opposed slavery, they supported the South's right to secede. Indeed, several provinces were advocating "separation" in 1861 and saw the Civil War as a cautionary tale demonstrating the danger of waiting to address irreconcilable differences. As the war unfolded, editors and government officials throughout New Zealand also worried about the wider economic effect of the war and the threat of American privateers attacking shipping and cities in the British colony.
A Digital Underwater Video Camera System for Aquatic Research in Regulated Rivers
Authors: Martin Benjamin M. , Irwin Elise R.
Published: January 2011

We designed a digital underwater video camera system to monitor nesting centrarchid behavior in the Tallapoosa River, Alabama, 20 km below a peaking hydropower dam with a highly variable flow regime. Major components of the system included a digital video recorder, multiple underwater cameras, and specially fabricated substrate stakes. The innovative design of the substrate stakes allowed us to effectively observe nesting redbreast sunfish Lepomis auritus in a highly regulated river. Substrate stakes, which were constructed for the specific substratum complex (i.e., sand, gravel, and cobble) identified at our study site, were able to withstand a discharge level of approximately 300 m3/s and allowed us to simultaneously record 10 active nests before and during water releases from the dam. We believe our technique will be valuable for other researchers that work in regulated rivers to quantify behavior of aquatic fauna in response to a discharge disturbance.
A Survey of Bowfishing Tournaments in Arkansas
Authors: Quinn Jeffrey W.
Published: January 2011

Bowfishing is an understudied method of fishing that appears to be legal throughout the United States. Therefore, species composition and harvest rates were determined at six bowfishing tournaments held in Arkansas at the lower White River, the Arkansas River at Lake Dardanelle, the Arkansas River at Piney Bay, Lake DeGray, Bull Shoals Lake, and Lake Ouachita between July 1999 and May 2000. A total of 3,280 fish were harvested at the six tournaments; of this total, 2,751 fish representing 19 species were identified. Total harvest per tournament ranged from 179 to 1,674 fish and from 6 to 12 species. Mean (±SD) harvest rate for tournament participants was 3.8 ± 1.1 fish/h; among tournament winners, the harvest rate was 7.7 ± 2.8 fish/h, which appears high compared with other sport fisheries (range = 0.28–2.59 fish/h). Five species accounted for 84% of fish harvested: spotted gar Lepisosteus oculatus, common carp Cyprinus carpio, shortnose gar L. platostomus, spotted sucker Minytrema melanops, and smallmouth buffalo Ictiobus bubalus. Rank number of each species harvested at the tournaments was correlated (P < 0.05) for only 4 of 15 pairwise comparisons, which suggests that harvest often varies by tournament. Tournaments held at the Arkansas and White rivers had correlated harvest, as did spring tournaments held at the Ouachita River drainage reservoirs (i.e., Lake DeGray and Lake Ouachita). Harvest of fish smaller than published size-at-maturity estimates was generally not problematic but appeared to be of greatest concern for smaller-bodied catostomid species. This study indicates that tournament bowfishers have higher harvest rates than traditional rod-and-reel anglers. Results of this survey should provide baseline information that may assist natural resource agencies with management of bowfishing.
An Empirical Assessment of PHABSIM Using Long-Term Monitoring of Coho Salmon Smolt Production in Bingham Creek, Washington
Authors: Beecher Hal A. , Caldwell Brad A. , DeMond S. Brett , Seiler Dave , Boessow Steven N.
Published: January 2011

We conducted a PHABSIM study on Bingham Creek, Washington, by using validated habitat suitability criteria for the rearing of coho salmon Oncorhynchus kisutch. We compared the relationship between weighted usable area (WUA) and flow with a previously determined empirical relationship that showed increasing coho salmon smolt production with increasing summer low flow (). The relationship between juvenile coho salmon WUA and flow indicated that the greatest amount of habitat occurred at a flow that was lower than our low-flow measurement, and the amount of habitat decreased with increasing flow. Thus, PHABSIM results were contrary to empirical measurement of coho salmon smolt production. Based on the relationship between summer flow and smolt production, production of smolts would decline if flow was reduced to the flow that maximizes WUA. The failure of PHABSIM to be consistent with empirical results may have be related to habitat suitability being influenced more by the numerous subdominant, schooling juvenile coho salmon and less by the dominant, territorial individuals, which have higher survival and prefer higher velocities.
Power of Revisit Monitoring Designs to Detect Forestwide Declines in Trout Populations
Authors: Dauwalter Daniel C. , Rahel Frank J. , Gerow Kenneth G.
Published: January 2011

Managers are often required to monitor networks of sites to make inferences about trends in fish populations over large geographic areas. We evaluated the statistical power of four revisit monitoring designs (always revisit design; two types of augmented serially alternating design; and serially alternating design) to detect declines in trout population biomass over a 30-year time horizon. The Medicine Bow National Forest, Wyoming, was used as a case study, and the designs were based on sampling 20 or 30 sites every other year but varied in the total number of sites (20–40 or 30–60) and the timing and frequency with which sites were monitored. The always revisit design, in which the same 20 or 30 sites were sampled during every monitoring period, often had slightly higher power than the other designs. However, any differences in power quickly diminished due to the rapid increase in power over time for all four designs. The similar levels of statistical power to detect population declines among the designs we evaluated suggest that managers have flexibility to choose a revisit design with increased spatial coverage and implementation complexity without sacrificing trend detection capability.
Effects of Healing Time and Pulsed-DC Waveform on Injury Detection and Incidence in Electroshocked Juvenile Chinook Salmon
Authors: Holliman F. M. , Reynolds J. B. , Holmes J. A. S.
Published: January 2011

Electrofishing is widely used to assess juvenile Pacific salmonids in freshwaters, but electroshock-induced injury may result. The small size of juvenile fish makes detection of internal injuries, particularly spinal injuries, more difficult than in adult fish. To test the idea that growth and healing of vertebral injuries over time would render injuries more detectable, we exposed age-1 Chinook salmon Oncorhynchus tshawytscha to conventional 60-Hz pulsed direct current (PDC) and dual-frequency PDC (DFPDC; 568 and 15 Hz) in a tank study. To simulate field conditions, capture-prone behaviors (immobilization and forced swimming) were achieved by applying 60-Hz PDC at a voltage gradient of 1.1 V/cm and DFPDC at 5.0 V/cm. Because electroshock treatments occurred only on day 0, we assumed that all injuries occurred on that day. Evaluation of injuries on days 1, 7, 14, 28, and 56 of a 56-d experiment revealed decreasingly detectable hemorrhages (as a result of healing) but increasingly detectable spinal injuries. Incidences of spinal injury induced by 60-Hz PDC and 568-Hz and 15-Hz DFPDC were both high (40–80% range) and not significantly different. However, fish responses to electroshock (behavior, bruising, mortality, and growth) followed a trend of greater severity for PDC than for DFPDC. Fewer age-0 fish were available; on day 0, they were exposed only to PDC and evaluated only on days 1 and 56. The most marked increase in detection of spinal injuries was observed in age-0 fish: the injury rate increased from 0% on day 1 to 53% on day 56. Immobilization of Chinook salmon (and presumably other juvenile salmonids) by 60-Hz PDC will cause significant trauma. Use of dual-frequency PDC, even at the higher voltage levels sufficient to immobilize these fish, will reduce these effects. Estimates of spinal injury rates in electroshocked juvenile salmonids may be biased downward unless sufficient time has passed for healing and growth to occur, thereby increasing the probability of radiographic detection.
A Likelihood Framework for Joint Estimation of Salmon Abundance and Migratory Timing Using Telemetric Mark—Recapture
Authors: Bromaghin Jeffrey F. , Gates Kenneth S. , Palmer Douglas E.
Published: January 2011

Many fisheries for Pacific salmon Oncorhynchus spp. are actively managed to meet escapement goal objectives. In fisheries where the demand for surplus production is high, an extensive assessment program is needed to achieve the opposing objectives of allowing adequate escapement and fully exploiting the available surplus. Knowledge of abundance is a critical element of such assessment programs. Abundance estimation using mark—recapture experiments in combination with telemetry has become common in recent years, particularly within Alaskan river systems. Fish are typically captured and marked in the lower river while migrating in aggregations of individuals from multiple populations. Recapture data are obtained using telemetry receivers that are co-located with abundance assessment projects near spawning areas, which provide large sample sizes and information on population-specific mark rates. When recapture data are obtained from multiple populations, unequal mark rates may reflect a violation of the assumption of homogeneous capture probabilities. A common analytical strategy is to test the hypothesis that mark rates are homogeneous and combine all recapture data if the test is not significant. However, mark rates are often low, and a test of homogeneity may lack sufficient power to detect meaningful differences among populations. In addition, differences among mark rates may provide information that could be exploited during parameter estimation. We present a temporally stratified mark—recapture model that permits capture probabilities and migratory timing through the capture area to vary among strata. Abundance information obtained from a subset of populations after the populations have segregated for spawning is jointly modeled with telemetry distribution data by use of a likelihood function. Maximization of the likelihood produces estimates of the abundance and timing of individual populations migrating through the capture area, thus yielding substantially more information than the total abundance estimate provided by the conventional approach. The utility of the model is illustrated with data for coho salmon O. kisutch from the Kasilof River in south-central Alaska.
Electrofishing Practices Have Limited Effects on Largemouth Bass Feeding Behavior
Authors: Siepker Michael J. , Ostrand Kenneth G. , Ball Elizabeth L. , Wahl David H.
Published: January 2011

Electrofishing is an effective fish capture technique used by many fisheries professionals. Despite the overall effectiveness of the technique, there have been reported negative consequences attributed to its use. We investigated the time to resumption of feeding for adult largemouth bass Micropterus salmoides subjected to electrofishing procedures compared with that for control fish across a range of sizes and water temperatures. Control fish fed immediately, whereas the resumption of feeding was delayed for a short period in electrofished largemouth bass. Time to resumption of feeding was not influenced by temperature but was influenced by largemouth bass size, with larger fish taking longer to resume feeding than smaller conspecifics. Although a single electrofishing event had limited effects on feeding behavior of largemouth bass, fisheries professionals should remain cognizant of other potential negative effects on fishes.
High altitude pulmonary edema
Authors: Hackett Peter H. , Roach Robert C.
Published: January 2011

High altitude pulmonary edema (HAPE) is a non-cardiogenic edema which afflicts susceptible persons who ascend to altitudes above 2500 meters and remain there for 24 to 48 h or longer. Incidence varies with the rate of ascent and the altitude, while contributing factors include exertion and perhaps cold. Individuals susceptible to HAPE have low hypoxic ventilatory drive and an increased pulmonary vasoconstrictor response to hypoxia. Pathophysiologically, excessive pulmonary hypertension is the sine qua non of HAPE, but other factors must also be present to produce permeability edema.

Clinical manifestations of mild HAPE are dyspnea with exertion, decreased exercise ability, and dry cough. Symptoms of more advanced HAPE are dyspnea, tachycardia, and tachypnea at rest, cyanosis, ataxia, change in consciousness and productive cough. Coma may rapidly ensue. Death usually follows misdiagnosis and lack of prompt treatment. Therapy consists of improving oxygenation and reducing pulmonary hypertension either by giving supplemental oxygen or descending to a lower altitude. Positive airway pressure devices, morphine, and diuretics may be adjunctive therapy, primarily when oxygen and/or descent are not possible. The leak rapidly reverses with treatment, and without residual lung damage. Slow, gradual ascent is the best prevention of HAPE, but acetazolamide has been anecdotally effective for HAPE-susceptibles. The capricious nature of the disorder mandates better public education efforts so that HAPE can be correctly recognized and treated.
Tibet: human and medical geography
Authors: Ward M.P.
Published: January 2011

The Tibetans probably originated in south-east Tibet, and are currently comprised largely of agriculturalists and nomads. In the 18th Century, about 20% were monks. Persons live at altitudes from 3600 m to 5400 m. This may be a factor in the incidence of chronic mountain sickness. Cold is combated by cultural methods, although some lamas are able to ‘warm without fire.’ Acute mountain sickness is well recognised. A low birth weight is common and menarche is delayed; age span does not appear to be increased. Goitre, measles, venereal diseases, chest infections and leprosy are common. Congenital cardiac abnormalities and pulmonary hypertension are often associated with systemic hypertension.
Normal oral flora in black bears: guidelines for antimicrobial prophylaxis following bear attacks
Authors: Floyd T. , Manville A.M. , French S.P.
Published: January 2011

Injuries sustained from bear attacks are often severe or fatal. Victims may require hospitalization and/or surgical debridement. Occasionally, serial debridements and reconstructive surgery are necessary. This study identifies aerobic oral flora in black bears ( Ursus americanus) and provides guidelines for antimicrobial prophylaxis of these wounds.
Venomous bites by nonvenomous snakes: an annotated bibliography of colubrid envenomation
Authors: Minton S.A.
Published: January 2011

This bibliography lists 71 publications dealing with human envenomation by colubrid snakes during the years 1873–1988. This information appears in a wide variety of publications in medicine, herpetology, and toxicology. Fifty snake species, many conventionally considered nonvenomous, are included. Reports are divided into those showing evidence of systemic poisoning, usually associated with coagulopathy, and those showing only local signs and symptoms.
Airway warming in the treatment of accidental hypothermia: a review
Authors: Lloyd E.L.
Published: January 2011

Airway warming is a method of treating accidental hypothermia which has provoked controversy. This review is intended to provide an accurate assessment of the current position. The effects of airway warming are to produce, as an adjunctive measure, a statistically significant increase in the rate of rewarming; decrease mortality from accidental hypothermia except in cases of subchronic hypothermia; and improve the cardiovascular, respiratory and cerebral status of the patient.

Suitable equipment is available to enable field airway warming, even in hostile environments. No individual design is perfect for all situations. A heat and moisture exchanger is the simplest, lightest and least expensive design, though not the most thermally efficient.

Airway warming should be of value for field use by rescue services. The technique still requires extensive evaluation to identify its potential and limitations.
Triggerfish bite – a little-known marine hazard
Authors: Randall J.E. , Millington J.T.
Published: January 2011

Injury to divers in tropical and subtropical waters from bites by triggerfishes have not been documented in the medical literature or in books and papers dealing with dangerous marine animals. Reports are given of five cases of divers sustaining bites from triggerfishes. The most dangerous of the triggerfishes are the tropical Indo-Pacific species Pseudobalistes fuscus and Balistotoides viridescens. Ordinarily these two fishes are very shy, but females guarding a nest can become extremely aggressive. Divers should not continue to swim toward a large triggerfish that does not move away upon their approach. Divers should also be warned not to feed triggerfishes by hand, as even small species are capable of inflicting bite wounds on the hands.
High incidence of mild acute mountain sickness in conference attendees at 10 000 foot altitude
Authors: Dean A.G. , Yip R. , Hoffmann R.E.
Published: January 2011

An epidemic of mild acute mountain sickness (AMS) occurred at a 4-day meeting of epidemiologists held at an altitude of 3000 m (9800 ft) in the Rocky Mountains of Colorado, USA. Questionnaires from 96% of the 105 attendees documented the following symptom frequencies: headache, 59%; shortness of breath, 59%; difficulty in sleeping, 45%; weakness or dizziness, 40%; and nausea, 12%. AMS, defined as three or more symptoms, occurred in 42% of the respondents, and 90% had at least one symptom. One third felt the illness interfered with their concentration at the meeting, and 31% would not plan another meeting at this altitude, although only one person missed meeting sessions as a result of the AMS. AMS should be anticipated by those planning meetings of short duration at high altitude, and by physicians advising travelers to altitudes over 2000 m.
The patient with coronary heart disease at altitude: observations during acute exposure to 3100 meters
Authors: Morgan B.J. , Alexander J.K. , Nicoli S.A. , Brammell H.L.
Published: January 2011

Nine men with documented coronary artery disease who had exercise-induced angina and/or ST segment depression were studied by treadmill testing at 1600 m and during acute exposure to 3100 m altitude. Mean maximal oxygen uptake was reduced at altitude by 11% (range, 5–26%). Ventilation, heart rate, and systolic pressure at submaximal workloads were increased at 3100 m, but maximal values were unchanged. Oxygen saturation was reduced at rest, and during submaximal and maximal exercise (88.3 ± 14 vs 93.4 ± 0.7%). Angina and/or ST segment depression occurred at the same heart rate systolic pressure product, but at lower workloads. Systolic time intervals were unchanged at altitude.

A target heart rate range of 70–85% of the ischemic end-point rate at lower altitude predicted an appropriate level of tolerable exercise at high altitude. We conclude that activity prescription for coronary patients with angina on arrival at high altitude should be based on heart rate rather than workload.
Coronary heart disease and trekking
Authors: Hultgren H.N.
Published: January 2011

A substantial number of men and women over 50 years of age engage in trekking, skiing and mountaineering, in many instances at elevations from 8000 ft (2440 m) to 18000 ft (5490 m). Many of these individuals have known coronary artery disease or, if asymptomatic, may have subclinical coronary disease. Several observations are pertinent: (1) The risk of sudden death or acute infarction during vigorous exercise, such as during symptom limited exercise tests, rehabilitation programs or jogging, is extremely small; (2) In patients with known or suspected coronary disease, exercise testing should be performed to determine risk status before starting a program of vigorous exercise; (3) Low risk patients can be reassured that exercise is not harmful and appropriate medical management can be instituted; (4) High risk patients should be referred for coronary arteriography to establish the appropriate management, i.e., medical, surgical or angioplasty. Exercise testing in asymptomatic patients without risk factors for coronary disease is not usually indicated; and (5) Upon ascent to high altitude, symptoms of coronary disease are usually increased for the first few days after arrival due to increased sympathetic stimulation induced by hypoxemia. There is no evidence that exercise after acclimatization at high altitude is of greater risk to the heart than similar exercise performed at sea level.
Successful use of the Gamow Hyperbaric Bag in the treatment of altitude illness at Mount Everest
Authors: King S.J. , Greenlee R.R.
Published: January 2011

Descent, the definitive treatment of altitude illness, can be simulated through the use of a new medical device, the Gamow Hyperbaric Bag (Gamow Bag). The Gamow Bag was field tested on Mount Everest during the 1988 Wyoming Centennial Everest Expedition (WCEE). We report six cases of acute mountain sickness which were managed in part with the Gamow Bag. All of the patients presented with dyspnea, weakness, and headache. They were treated with combinations of the Gamow Bag, oxygen, and descent. The patients were in the Gamow Bag from 1 to 10 h. After treatment, three of the patients had complete resolution of their symptoms and later ascended to or above the altitude where they first became ill. The other three patients were able to continue descent without incident. The Gamow Bag is a useful device in the treatment of altitude illness.
Granuloma annulare following bluebottle jellyfish (Physalia utriculus) sting
Authors: Mandojana R.M.
Published: January 2011

This report describes the case of a teenager stung by a Pacific bluebottle jellyfish ( Physalia utriculus) in Hawaii, who subsequently developed classical lesions of granuloma annulare. It is speculated that various toxic substances found in the complex venom of this particular coelenterate may be responsible for initiating the pathophysiologic mechanism.
Brown recluse spider bites in an urban wilderness
Authors: Erickson T. , Hryhorczuk D.O. , Lipscomb J. , Burda A. , Greenberg B.
Published: January 2011

Loxoscelism or necrotic arachnidism are the terms used to describe the effects of the brown recluse spider bite. Over recent years, there has been a steady increase in the number of reported brown recluse spider bites. It is not clear whether this represents an expanded range of the spider's habitat or greater physician awareness. Although most commonly found in the warm, south central region of the United States, Loxosceles reclusa can be a cause of necrotic arachnidism in northern urban settings. Therefore, the diagnosis should also be considered in these areas. This article discusses three cases of suspected brown recluse spider bites referred to a Chicago-based poison control center and briefly reviews the literature regarding the diagnosis, clinical presentation and treatment of loxoscelism.
Persistent headache associated with scombroid poisoning: resolution with oral cimetidine
Authors: Auerbach P.S.
Published: January 2011

This case report describes a classical case of scombroid fish poisoning, following which the victim suffered persistent headache, abdominal cramps and diarrhea. The sequelea of the intoxication were refractory to symptomatic therapy. An oral histamine-2 antagonist, cimetidine, successfully relieved the victim of her symptoms. This is the first description of an effective therapy for the clinical residua following a bout of scombrotoxism.
Rabies immunoprophylaxis strategy in travelers
Authors: Shlim D.R. , Schwartz E. , Houston R.
Published: January 2011

We present data from a two-year study of foreign travelers with possible exposure to rabies virus who presented to the only clinics in Nepal that provided modern rabies vaccine. Of 395 000 foreign tourists and residents who visited Nepal during the study period, 62 required post-exposure rabies immunoprophylaxis. Dog bites accounted for 76% of the exposures, while 20% were due to monkey bites. Sixty-three percent of wounds involved the lower extremity. Seventy-eight per cent of wounds were 2 cm or less in length. The mean length of time between exposure and treatment was 3 days, and 90% received consultation or treatment within 9 days. The safety, expense, and convenience of pre-exposure rabies immunization versus post-exposure immunoprophylaxis alone are discussed.
Hemolytic anemia and hemoglobinuria due to systemic loxoscelism: report of a case
Authors: Michaud M.E. , Gibler W.B.
Published: January 2011

Hemolytic anemia and hemoglobinuria are rare consequences of brown recluse spider bites. These systemic complications are frequently associated with skin necrosis at the envenomation site. In this case report, a 6-year-old boy developed these systemic features with formation of a small, typical brown recluse spider bite skin lesion without overt skin necrosis. In addition to the case report, the variety of clinical presentations, proposed pathogenesis, and treatment modalities of brown recluse spider bites are reviewed.
Acceleration of wound healing responses induced by preparations from the epidermal secretions of the Arabian Gulf catfish (Arius bilineatus, Valenciennes)
Authors: Al-Hassan J.M. , Dyson M. , Young S.R. , Thomson M. , Criddle R.S.
Published: January 2011

Preparations involving fright-induced epidermal secretions from the Arabian Gulf catfish (Arius bilineatus) have been observed to accelerate wound healing in test animals. In this investigation, solubilized preparations containing 4–8 mg of protein were applied once to excised and incised full-thickness lesions of the flank skin of adult male mice (strain CD1) immediately after injury, while sterile saline was applied to the surface of control wounds. Changes in wound closure were assessed from photographs taken of the wound surface, while changes in cellularity were assessed by light microscopy. In excised lesions, a temporary reduction (lasting less than 24 h) was observed in the surface area of test wounds, while control wounds exhibited a temporary increase in surface area (wound gape). In incised lesions, the edges of test wounds treated with the preparations adhered to each other, while the edges of control wounds remained separated. Total and differential cell counts made in equivalent areas of excised wound beds showed that by 7 days after injury, there were significantly more fibroblasts and fewer inflammatory cells in the test group than in the controls, suggesting that the wounds treated with the preparations were at a more advanced stage of repair.