Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update.

The Wilderness Medical Society (WMS) convened an expert panel in 2011 to develop a set of evidence-based guidelines for the recognition, prevention, and treatment of heat illness. The current panel retained 5 original members and welcomed 2 new members, all of whom collaborated remotely to provide an updated review of the classifications, pathophysiology, evidence-based guidelines for planning and preventive measures, and recommendations for field- and hospital-based therapeutic management of heat illness. These recommendations are graded based on the quality of supporting evidence and the balance between the benefits and risks or burdens for each modality. This is an updated version of the WMS clinical practice guidelines for the prevention and treatment of heat illness published in Wilderness & Environmental Medicine. 2019;30(4):S33-S46.

Failure to Participate in Sports: An Evaluation of Preparticipation Physicals in a Local School District.

PURPOSE: To determine the incidence of the documentation of athlete failure of preparticipation sports physicals. METHODS: This was a retrospective observational study that involved review of preparticipation examination physical form documentation from multiple clinicians for all student athletes who participated in athletics during the 2018 to 2019 academic year at Galveston Independent School District (GISD). We collected the reasons for failure to pass the preparticipation physical examination. RESULTS: Of the approximately 800 student athlete forms reviewed, 183 forms indicated individual athletes failed the visual acuity or cardiovascular portions of the preparticipation physical examination. DISCUSSION: Athlete failures of the preparticipation physical examination may cause delays in sports participation, and time and monetary costs to students and their parents. Inconsistences in guidelines used to clear athletes as well as variation in form completion impacts whether athletes reportedly failed or passed the examination. Mass participation screening becomes a safety net for communities for athletes who may not have primary care providers to encourage follow-up with a regular clinician for previously undiagnosed medical issues and standardizing guideline use and form completion across clinicians who do these exams may improve numbers of athletes who are cleared to play sports. CONCLUSION: Focusing on preventable and addressable preparticipation examination failures may help clinicians who perform these exams, while also establishing a safety net for previously undiagnosed medical conditions. Instituting yearly vision checks, addressing cardiovascular issues, and encouraging yearly follow-up with primary care clinicians can more readily address physical and mental health issues and will provide more comprehensive care to student athletes.

Electrophysiological effects of smartphone notifications on cognitive control following a brief mindfulness induction.

Smartphone use is nearly ubiquitous, with 93% of adults among economically developed countries, including the United States, Canada, Israel, and South Korea owning a smartphone (Taylor & Silver, 2019). Multiple studies have demonstrated the distracting effects of smartphone notifications on behavioral measures of cognition. Fewer studies have examined the effects of notifications on neural activity underlying higher-level cognitive processes or behavioral inductions to reduce smartphone-related distraction. Using EEG spectral frequency power densities, we assessed the effects of smartphone notifications (vs. control trials) on engagement of attentional shifting processes involved in cognitive control during a Navon Letter visual oddball task. Participants were randomly assigned to a brief mindfulness induction (N = 44) or a neutral narration control condition (N = 43). Overall, participants had lower theta-band power, but higher alpha- and beta-band power densities on target letter trials preceded by smartphone notifications. Additionally, participants in the mindfulness (vs. control) condition had a larger attention shifting oddball assessed via theta power density and theta/beta ratio (TBR) values-reflecting increased engagement of cognitive control-particularly on smartphone notification (vs. control) trials. Altogether, these results provide evidence supporting the idea that smartphone notifications can decrease activity of neural correlates of cognitive control, and offer the promise of a brief mindfulness induction to buffer against the effects of smartphone notifications on cognitive control. The findings indicate a need for further research on mindfulness inductiosn as a means to reduce potential distraction caused by smartphones.

A novel approach using electroacupuncture for erectile dysfunction after radical prostatectomy: A case report.

INTRODUCTION: Research shows that electrical stimulation to damaged peripheral nerves has promising effects on nerve regeneration and recovery of function. DESCRIPTION: A 71 yr. old male, who was 12 months post left intrafacial and right incremental nerve sparing robotic radical prostatectomy received 6 sessions of sacral electroacupuncture/acupuncture at weekly intervals, commencing 12 months post operatively. METHODS: CARE guidelines informed the case study report. Positive changes in erectile function after electroacupuncture was recorded using validated scores (IIEF-5 and EHS). Qualitative information was collected via a feedback box. DISCUSSION: Given that current treatments for post radical prostatectomy erectile dysfunction are invasive and largely unsuccessful, further investigation into electroacupuncture for this population should be pursued.

Changes in the expression of inflammatory and epigenetic-modulatory genes after an intensive meditation retreat.

Background: Meditation retreats are characterized by intensive or concentrated periods of meditation practice, commonly undertaken in a residential setting. Although research indicates that meditation training can positively influence physical and mental health outcomes, the biological consequences of meditation retreat interventions are relatively understudied. In this study, we examined the influence of a month-long, silent meditation retreat on the expression of genes involved in epigenetic modulation and immune processes. Method: We assessed gene expression changes in experienced meditators attending a month-long Insight meditation retreat (n = 28), as compared to a community control group (n = 34) of experienced practitioners living their everyday lives. Blood samples were collected on day two of the retreat (Time 1) and again 3 weeks later (Time 2). Control participants were also assessed across a 3-week interval, during which they maintained their regular daily routines. Results: As compared to controls, retreat participants showed differential changes in the expression of several genes involved in chromatin modulation and inflammation. The most substantive finding was downregulation of the TNF pathway in retreat participants, which was not observed in controls. Conclusions: These findings indicate that meditation retreat participation may influence some of the inflammatory mechanisms involved in the development of chronic diseases, and that this style of psychosocial intervention may have therapeutic potential, particularly in experienced practitioners.

Wide-awake local anaesthesia no tourniquet (WALANT) vs regional or general anaesthesia for flexor tendon repair in adults: protocol for a systematic review and meta-analysis.

BACKGROUND: Flexor tendon injuries most commonly occur following a penetrating injury to the hand or wrist. These are challenging injuries and the standard treatment is surgical repair under general or regional anaesthesia. 'Wide-awake' surgery is an emerging technique in hand surgery where a conscious patient is operated on under local anaesthetic. The vasoconstrictive effect of adrenaline (epinephrine) creates a 'bloodless' operating field and a tourniquet is not required. The potential advantages include intra-operative testing of the repair; removal of the risks of general anaesthesia; reduced costs; no aerosol generation from intubation therefore reduced risk of COVID-19 spread to healthcare professionals. The aim of this study will be to systematically evaluate the evidence to determine if wide-awake surgery is superior to general/regional anaesthetic in adults who undergo flexor tendon repair. METHODS: We designed and registered a study protocol for a systematic review and meta-analysis of comparative and non-comparative studies. The primary outcome will be functional active range of motion. Secondary outcomes will be complications, resource use (operative time) and patient-reported outcome measures. A comprehensive literature search will be conducted (from 1946 to present) in MEDLINE, EMBASE, CINAHL, and Cochrane Library. Grey literature will be identified through Open Grey, dissertation databases and clinical trials registers. All studies on wide-awake surgery for flexor tendon repair will be included. The comparator will be general or regional anaesthesia. No limitations will be imposed on peer review status or language of publication. Two investigators will independently screen all citations, full-text articles and abstract data. Potential conflicts will be resolved through discussion or referral to a third author when necessary. The study methodological quality (or bias) will be appraised using an appropriate tool. If feasible, we will conduct a random effects meta-analysis. DISCUSSION: This systematic review will summarise the best available evidence and definitively establish if function, complications, cost, or patient-reported outcomes are improved when flexor tendons are repaired using wide-awake technique. It will determine if this novel approach is superior to general or regional anaesthesia. This knowledge will help guide hand surgeons by continuing to improve outcomes from flexor tendon injuries. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42020182196.

Deconstructing the effects of concentration meditation practice on interference control: The roles of controlled attention and inflammatory activity.

Prior work has linked meditation practice to improvements in interference control. However, the mechanisms underlying these improvements are relatively unknown. In the context of meditation training, improvements in interference control could result eitherfrom increases in controlled attention to goal-relevant stimuli, or from reductions in automatic capture by goal-irrelevant stimuli. Moreover, few studies have linked training-related changes in attention to physiological processes, such as inflammatory activity, that are thought to influence cognitive function. This study addresses these gaps by examining associations between cognitive performance and cytokines in the context of an intensive meditation retreat. Participants were randomly assigned to complete 3 months of meditation training first, or to serve as waitlist controls. The waitlist-control participants then later completed a separate 3-month training intervention. We assessed participants' interference control with a flanker task and used computational modeling to derive component processes of controlled and automatic attention. We also collected blood samples at the beginning, middle, and end of training to quantify changes in cytokine activity. Participants who completed training evidenced better controlled attention than waitlist controls during the first retreat intervention, and controls showed significant improvements in controlled attention when they completed their own, second retreat. Importantly, inflammatory activity was inversely associated with controlled attention during both interventions. Our results suggest that practice of concentration meditation influences interference control by enhancing controlled attention to goal-relevant task elements, and that inflammatory activity relates to individual differences in controlled attention.

Day of Ascent Dosing of Acetazolamide for Prevention of Acute Mountain Sickness.

Background: Acetazolamide is the most common medication used for prevention of acute mountain sickness (AMS), usually administered the day or night before ascent. The objective of this study was to evaluate the efficacy of day of ascent dosing of acetazolamide for AMS prevention. Methods: Double-blind, randomized, controlled noninferiority trial of acetazolamide 125 mg twice daily beginning either the night before or the morning of ascent. Healthy low altitude adults ascended from 1240 m (4100 ft) to 3810 m (12,570 ft) during summer 2018 on White Mountain, California. Primary outcome was incidence of AMS with the two different dosing patterns, assessed by the 1993 Lake Louise Questionnaire (LLQ) of ≥3 with headache and a minimum of 1 for other symptom. Results: One hundred four participants completed the study, with 54 (52%) randomized to night before acetazolamide and 50 (48%) to day of ascent dosing, without differences in baseline characteristics. There was 9% greater incidence of AMS in the day of ascent acetazolamide group (48.0% vs. 39%, 95% confidence interval [CI] -11.8 to 30, p = 0.46, number needed to treat [NNT] = 5.6 vs. 3.7), with the CI just surpassing the predetermined 26% noninferiority margin. There was a lower incidence of severe AMS (1993 LLQ >5) in the day of ascent group (n = 5, 10%, NNT = 2.3) compared with night before dosing (n = 12, 22%, NNT = 3.1) (95% CI -28 to 3.6), and lower average symptom severity in the day of ascent group (3 vs. 3.5, 95% CI -0.5 to 1.4). Conclusions: Day of ascent acetazolamide demonstrated higher rates of AMS compared with traditional dosing by a small margin. With similar rates of severe AMS and overall symptom severity, the potential for improved convenience and compliance may support day of ascent use.

Effects of Yoga on Attention, Impulsivity, and Hyperactivity in Preschool-Aged Children with Attention-Deficit Hyperactivity Disorder Symptoms.

OBJECTIVE: Behavioral therapies are first-line for preschoolers with attention-deficit hyperactivity disorder (ADHD). Studies support yoga for school-aged children with ADHD; this study evaluated yoga in preschoolers on parent- and teacher-rated attention/challenging behaviors, attentional control (Kinder Test of Attentional Performance [KiTAP]), and heart rate variability (HRV). METHODS: This randomized waitlist-controlled trial tested a 6-week yoga intervention in preschoolers with ≥4 ADHD symptoms on the ADHD Rating Scale-IV Preschool Version. Group 1 (n = 12) practiced yoga first; Group 2 (n = 11) practiced yoga second. We collected data at 4 time points: baseline, T1 (6 weeks), T2 (12 weeks), and follow-up (3 months after T2). RESULTS: At baseline, there were no significant differences between groups. At T1, Group 1 had faster reaction times on the KiTAP go/no-go task (p = 0.01, 95% confidence interval [CI], -371.1 to -59.1, d = -1.7), fewer distractibility errors of omission (p = 0.009, 95% CI, -14.2 to -2.3, d = -1.5), and more commission errors (p = 0.02, 95% CI, 1.4-14.8, d = 1.3) than Group 2. Children in Group 1 with more severe symptoms at baseline showed improvement at T1 versus control on parent-rated Strengths and Difficulties Questionnaire hyperactivity inattention (ß = -2.1, p = 0.04, 95% CI, -4.0 to -0.1) and inattention on the ADHD Rating Scale (ß = -4.4, p = 0.02, 95% CI, -7.9 to -0.9). HRV measures did not differ between groups. CONCLUSION: Yoga was associated with modest improvements on an objective measure of attention (KiTAP) and selective improvements on parent ratings.

Ibuprofen versus placebo effect on acute kidney injury in ultramarathons: a randomised controlled trial.

BACKGROUND: Despite concerns that non-steroidal anti-inflammatory drugs (NSAIDs) contribute to acute kidney injury (AKI), up to 75% of ultramarathon runners ingest these during competition. The effect of NSAID on AKI incidence in ultramarathon runners is unclear. METHODS: Multisite randomised double-blind placebo-controlled trial in the Gobi, Atacama, Ecuador and Sri Lankan deserts to determine whether ibuprofen (400 mg every 4 hours) would be non-inferior to placebo during a 50-mile (80 km) foot race. The primary outcome was incidence of AKI defined as severity categories of 'risk' of injury of 1.5× baseline creatinine (Cr) or 'injury' as 2× Cr, combined to calculate total incidence at the finish line. Non-inferiority margin for difference in AKI rates was defined as 15%. RESULTS: Eighty-nine participants (47% ibuprofen and 53% placebo) were enrolled with similar demographics between groups. The overall incidence of AKI was 44%. Intent-to-treat analysis found 22 (52%) ibuprofen versus 16 (34%) placebo users developed AKI (18% difference, 95% CI -4% to 41%; OR 2.1, 95% CI 0.9 to 5.1) with a number needed to harm of 5.5. Greater severity of AKI was seen with ibuprofen compared with placebo (risk=38% vs 26%; 95% CI -9% to 34%; injury=14% vs 9%; 95% CI -10% to 21%). Slower finishers were less likely to encounter AKI (OR 0.67, 95% CI 0.47 to 0.98) and greater weight loss (-1.3%) increased AKI (OR 1.24, 95% CI 1.00 to 1.63). CONCLUSION: There were increased rates of AKI in those who took ibuprofen, and although not statistically inferior to placebo by a small margin, there was a number needed to harm of 5.5 people to cause 1 case of AKI. Consideration should therefore be taken before ingesting NSAID during endurance running as it could exacerbate renal injury. TRIAL REGISTRATION NUMBER: NCT02272725.

Developmental guidance of the retroflex tract at its bending point involves Robo1-Slit2-mediated floor plate repulsion.

The retroflex tract contains medial habenula efferents that target the hindbrain interpeduncular complex and surrounding areas. This tract displays a singular course. Initially, habenular axons extend ventralwards in front of the pretectum until they reach the basal plate. Next, they avoid crossing the local floor plate, sharply changing course caudalwards (the retroflexion alluded by the tract name) and navigate strictly antero-posteriorly across basal pretectum, midbrain and isthmus. Once they reach rhombomere 1, the habenular axons criss-cross the floor plate several times within the interpeduncular nuclear complex as they innervate it. Here we described the timing and details of growth phenomena as these axons navigate to their target. The first dorsoventral course apparently obeys Ntn1 attraction. We checked the role of local floor plate signaling in the decision to avoid the thalamic floor plate and bend caudalwards. Analyzing the altered floor and basal plates of Gli2 knockout mice, we found a contralateral projection of most habenular axons, plus ulterior bizarre navigation rostralwards. This crossing phenotype was due to a reduced expression of Slit repulsive cues, suggesting involvement of the floor-derived Robo-Slit system in the normal guidance of this tract. Using Slit and Robo mutant mice, open neural tube and co-culture assays, we determined that Robo1-Slit2 interaction is specifically required for impeding that medial habenular axons cross the thalamic floor plate. This pathfinding mechanism is essential to establish the functionally important habenulo-interpeduncular connection.

Integration of non-fuel coproducts into the GREET model.

The life-cycle greenhouse gas (GHG) emissions of alternative fuels that are capable of replacing conventional, petroleum-derived gasoline and diesel continue to be scrutinized for policy implementation. These alternative fuel technologies can also produce a number of value-adding nonfuel coproducts that require thorough and rigorous assessment in order to achieve an accurate life-cycle GHG emissions value. By using the gas to liquids (GTL) diesel pathway as a proxy for other alternative fuel pathways with coproducts, this paper examines how integration of coproduct analysis using the substitution method is possible within the existing framework and functionality of the GREET model. Using this approach, a GREET-compatible external tool was developed to calculate the life-cycle inventory of GTL coproducts to determine the life-cycle GHG emissions of GTL diesel using the substitution method. In addition to having built-in regional scenarios, this tool allows the user the flexibility to configure a given GTL product slate and to calculate the life-cycle GHG emissions of GTL diesel based on a given product composition. Using this protocol, the life-cycle GHG emissions of GTL diesel can range from 71.7 to 95.7 gCO2e/MJ on a well to wheel basis, with the range in carbon intensity being dependent on the mix of coproducts. These results highlight a weakly understood relationship between fuel and chemical products in LCA models. The coproduct integration approach described herein could potentially be incorporated into fuel LCA models, such as GREET, to allow users to further understand the potential environmental benefits of alternative fuel pathways, such as GTL.

Wilderness Medical Society practice guidelines for the prevention and treatment of heat-related illness: 2014 update.

The Wilderness Medical Society (WMS) convened an expert panel to develop a set of evidence-based guidelines for the recognition, prevention, and treatment of heat illness. We present a review of the classifications, pathophysiology, and evidence-based guidelines for planning and preventive measures as well as best practice recommendations for both field and hospital-based therapeutic management of heat illness. These recommendations are graded on the basis of the quality of supporting evidence, and balance between the benefits and risks or burdens for each modality. This is an updated version of the original WMS Practice Guidelines for the Prevention and Treatment of Heat-Related Illness published in Wilderness & Environmental Medicine 2013;24(4):351-361.

Energy efficiency and greenhouse gas emission intensity of petroleum products at U.S. refineries.

This paper describes the development of (1) a formula correlating the variation in overall refinery energy efficiency with crude quality, refinery complexity, and product slate; and (2) a methodology for calculating energy and greenhouse gas (GHG) emission intensities and processing fuel shares of major U.S. refinery products. Overall refinery energy efficiency is the ratio of the energy present in all product streams divided by the energy in all input streams. Using linear programming (LP) modeling of the various refinery processing units, we analyzed 43 refineries that process 70% of total crude input to U.S. refineries and cover the largest four Petroleum Administration for Defense District (PADD) regions (I, II, III, V). Based on the allocation of process energy among products at the process unit level, the weighted-average product-specific energy efficiencies (and ranges) are estimated to be 88.6% (86.2%-91.2%) for gasoline, 90.9% (84.8%-94.5%) for diesel, 95.3% (93.0%-97.5%) for jet fuel, 94.5% (91.6%-96.2%) for residual fuel oil (RFO), and 90.8% (88.0%-94.3%) for liquefied petroleum gas (LPG). The corresponding weighted-average, production GHG emission intensities (and ranges) (in grams of carbon dioxide-equivalent (CO2e) per megajoule (MJ)) are estimated to be 7.8 (6.2-9.8) for gasoline, 4.9 (2.7-9.9) for diesel, 2.3 (0.9-4.4) for jet fuel, 3.4 (1.5-6.9) for RFO, and 6.6 (4.3-9.2) for LPG. The findings of this study are key components of the life-cycle assessment of GHG emissions associated with various petroleum fuels; such assessment is the centerpiece of legislation developed and promulgated by government agencies in the United States and abroad to reduce GHG emissions and abate global warming.

U.S. refinery efficiency: impacts analysis and implications for fuel carbon policy implementation.

In the next two decades, the U.S. refining industry will face significant changes resulting from a rapidly evolving domestic petroleum energy landscape. The rapid influx of domestically sourced tight light oil and relative demand shifts for gasoline and diesel will impose challenges on the ability of the U.S. refining industry to satisfy both demand and quality requirements. This study uses results from Linear Programming (LP) modeling data to examine the potential impacts of these changes on refinery, process unit, and product-specific efficiencies, focusing on current baseline efficiency values across 43 existing large U.S. refineries that are operating today. These results suggest that refinery and product-specific efficiency values are sensitive to crude quality, seasonal and regional factors, and refinery configuration and complexity, which are determined by final fuel specification requirements. Additional processing of domestically sourced tight light oil could marginally increase refinery efficiency, but these benefits could be offset by crude rebalancing. The dynamic relationship between efficiency and key parameters such as crude API gravity, sulfur content, heavy products, residual upgrading, and complexity are key to understanding possible future changes in refinery efficiency. Relative to gasoline, the efficiency of diesel production is highly variable, and is influenced by the number and severity of units required to produce diesel. To respond to future demand requirements, refiners will need to reduce the gasoline/diesel (G/D) production ratio, which will likely result in greater volumes of diesel being produced through less efficient pathways resulting in reduced efficiency, particularly on the marginal barrel of diesel. This decline in diesel efficiency could be offset by blending of Gas to Liquids (GTL) diesel, which could allow refiners to uplift intermediate fuel streams into more efficient diesel production pathways, thereby allowing for the efficient production of incremental barrels of diesel without added capital investment for the refiner. Given the current wide range of refinery carbon intensity values of baseline transportation fuels in LCA models, this study has shown that the determination of refinery, unit, and product efficiency values requires careful consideration in the context of specific transportation fuel GHG policy objectives.

Bidirectional regulation of the cAMP response element binding protein encodes spatial map alignment in prism-adapting barn owls.

The barn owl midbrain contains mutually aligned maps of auditory and visual space. Throughout life, map alignment is maintained through the actions of an instructive signal that encodes the magnitude of auditory-visual mismatch. The intracellular signaling pathways activated by this signal are unknown. Here we tested the hypothesis that CREB (cAMP response element-binding protein) provides a cell-specific readout of instructive information. Owls were fitted with prismatic or control spectacles and provided rich auditory-visual experience: hunting live mice. CREB activation was analyzed within 30 min of hunting using phosphorylation state-specific CREB (pCREB) and CREB antibodies, confocal imaging, and immunofluorescence measurements at individual cell nuclei. In control owls or prism-adapted owls, which experience small instructive signals, the frequency distributions of pCREB/CREB values obtained for cell nuclei within the external nucleus of the inferior colliculus (ICX) were unimodal. In contrast, in owls adapting to prisms or readapting to normal conditions, the distributions were bimodal: certain cells had received a signal that positively regulated CREB and, by extension, transcription of CREB-dependent genes, whereas others received a signal that negatively regulated it. These changes were restricted to the subregion of the inferior colliculus that received optically displaced input, the rostral ICX, and were not evident in the caudal ICX or central nucleus. Finally, the topographic pattern of CREB regulation was patchy, not continuous, as expected from the actions of a topographically precise signal encoding discrete events. These results support a model in which the magnitude of CREB activation within individual cells provides a readout of the instructive signal that guides plasticity and learning.

Independent transcription of glutamine synthetase (glnA2) and glutamine synthetase adenylyltransferase (glnE) in Mycobacterium bovis and Mycobacterium tuberculosis.

Mycobacterium bovis and Mycobacterium tuberculosis possess four glutamine synthetase homologues, two of which, glnA1 and glnA2, are required for virulence and are located on the bacterial chromosome on either side of glutamine synthetase adenylyltransferase (glnE). While glnA1 is encoded on the complementary strand, glnA2 is located 48bp upstream from glnE, raising the possibility that glnA2 and glnE may be co-transcribed. However, previous studies in M. bovis and M. tuberculosis have painted a contradictory picture of the (co)transcriptional status of glnA2 and glnE. Given the importance of the genes at the glnA1-glnE-glnA2 locus, we sought to clarify the transcriptional status of glnA2 and glnE in both M. bovis and M. tuberculosis. Reverse transcription-PCR demonstrated that glnA2 and glnE were independently transcribed in all six M. bovis and M. tuberculosis strains examined. Northern analysis of the glnA2 transcript in M. bovis AF2122/97 and M. tuberculosis H37Rv showed that it was monocistronic. These results predicted the presence of a glnE transcriptional start site in the glnA2-glnE intergenic region. An identical start site was confirmed in M. bovis AF2122/97 and M. tuberculosis H37Rv using 5' rapid amplification of cDNA ends. Typical mycobacterial -10 and -35 sequences are associated with this start site.

Homozygous mutation of focal adhesion kinase in embryonic stem cell derived neurons: normal electrophysiological and morphological properties in vitro.

BACKGROUND: Genetically manipulated embryonic stem (ES) cell derived neurons (ESNs) provide a powerful system with which to study the consequences of gene manipulation in mature, synaptically connected neurons in vitro. Here we report a study of focal adhesion kinase (FAK), which has been implicated in synapse formation and regulation of ion channels, using the ESN system to circumvent the embryonic lethality of homozygous FAK mutant mice. RESULTS: Mouse ES cells carrying homozygous null mutations (FAK-/-) were generated and differentiated in vitro into neurons. FAK-/- ESNs extended axons and dendrites and formed morphologically and electrophysiologically intact synapses. A detailed study of NMDA receptor gated currents and voltage sensitive calcium currents revealed no difference in their magnitude, or modulation by tyrosine kinases. CONCLUSION: FAK does not have an obligatory role in neuronal differentiation, synapse formation or the expression of NMDA receptor or voltage-gated calcium currents under the conditions used in this study. The use of genetically modified ESNs has great potential for rapidly and effectively examining the consequences of neuronal gene manipulation and is complementary to mouse studies.

Comparison of stimulation patterns for FES-cycling using measures of oxygen cost and stimulation cost.

AIM: The energy efficiency of FES-cycling in spinal cord injured subjects is very much lower than that of normal cycling, and efficiency is dependent upon the parameters of muscle stimulation. We investigated measures which can be used to evaluate the effect on cycling performance of changes in stimulation parameters, and which might therefore be used to optimise them. We aimed to determine whether oxygen cost and stimulation cost measurements are sensitive enough to allow discrimination between the efficacy of different activation ranges for stimulation of each muscle group during constant-power cycling. METHODS: We employed a custom FES-cycling ergometer system, with accurate control of cadence and stimulated exercise workrate. Two sets of muscle activation angles ("stimulation patterns"), denoted "P1" and "P2", were applied repeatedly (eight times each) during constant-power cycling, in a repeated measures design with a single paraplegic subject. Pulmonary oxygen uptake was measured in real time and used to determine the oxygen cost of the exercise. A new measure of stimulation cost of the exercise is proposed, which represents the total rate of stimulation charge applied to the stimulated muscle groups during cycling. A number of energy-efficiency measures were also estimated. RESULTS: Average oxygen cost and stimulation cost of P1 were found to be significantly lower than those for P2 (paired t-test, p<0.05): oxygen costs were 0.56+/-0.03l min-1 and 0.61+/-0.04l min-1 (mean+/-S.D.), respectively; stimulation costs were 74.91+/-12.15 mC min-1 and 100.30+/-14.78 mC min-1 (mean+/-S.D.), respectively. Correspondingly, all efficiency estimates for P1 were greater than those for P2. CONCLUSION: Oxygen cost and stimulation cost measures both allow discrimination between the efficacy of different muscle activation patterns during constant-power FES-cycling. However, stimulation cost is more easily determined in real time, and responds more rapidly and with greatly improved signal-to-noise properties than the ventilatory oxygen uptake measurements required for estimation of oxygen cost. These measures may find utility in the adjustment of stimulation patterns for achievement of optimal cycling performance.

Pax6 guides a relay of pioneer longitudinal axons in the embryonic mouse forebrain.

We have characterized a system of early neurons that establish the first two major longitudinal tracts in the embryonic mouse forebrain. Axon tracers and antibody labels were used to map the axon projections in the thalamus from embryonic days 9.0-12, revealing several distinct neuron populations that contributed to the first tracts. Each of the early axon populations first grew independently, pioneering a short segment of new tract. However, each axon population soon merged with other axons to form one of only two shared longitudinal tracts, both descending: the tract of the postoptic commissure (TPOC), and, in parallel, the stria medullaris. Thus, the forebrain longitudinal tracts are pioneered by a relay of axons, with distinct axon populations pioneering successive segments of these pathways. The extensive merging of tracts suggests that axon-axon interactions are a major guidance mechanism for longitudinal axons. Several axon populations express tyrosine hydroxylase, identifying the TPOC as a major pathway for forebrain dopaminergic projections. To start a genetic analysis of pioneer axon guidance, we have identified the transcription factor Pax6 as critical for tract formation. In Pax6 mutants, both longitudinal tracts failed to form due to errors by every population of early longitudinal axons. Taken together, these results have identified potentially important interactions between series of pioneer axons and the Pax6 gene as a general regulator of longitudinal tract formation in the forebrain.