Predictive and protective factors for failing first pass intubation in prehospital rapid sequence intubation: an aetiology and risk systematic review with meta-analysis.

BACKGROUND: Prehospital rapid sequence intubation first pass success rates vary between 59% and 98%. Patient morbidity is associated with repeat intubation attempts. Understanding what influences first pass success can guide improvements in practice. We performed an aetiology and risk systematic review to answer the research question 'what factors are associated with success or failure at first attempt laryngoscopy in prehospital rapid sequence intubation?'. METHODS: MEDLINE, EMBASE, CINAHL, and Cochrane Library were searched on March 3, 2023 for studies examining first pass success rates for rapid sequence intubation of prehospital live patients. Screening was performed via Covidence, and data synthesised by meta-analysis. The review was registered with PROSPERO and performed and reported as per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: Reasonable evidence was discovered for predictive and protective factors for failure of first pass intubation. Predictive factors included age younger than 1 yr, the presence of blood or fluid in the airway, restricted jaw or neck movement, trauma patients, nighttime procedures, chronic or acute distortions of normal face/upper airway anatomy, and equipment issues. Protective factors included an experienced intubator, adequate training, use of certain videolaryngoscopes, elevating the patient on a stretcher in an inclined position, use of a bougie, and laryngeal manoeuvres. CONCLUSIONS: Managing bloody airways, positioning well, using videolaryngoscopes with bougies, and appropriate training should be further explored as opportunities for prehospital services to increase first pass success. Heterogeneity of studies limits stronger conclusions. SYSTEMATIC REVIEW PROTOCOL: PROSPERO (CRD42022353609).

Sodium Bicarbonate and Time-to-Exhaustion Cycling Performance: A Retrospective Analysis Exploring the Mediating Role of Expectation.

BACKGROUND: Research has shown that ingesting 0.3 g·kg-1 body mass sodium bicarbonate (NaHCO3) can improve time-to-exhaustion (TTE) cycling performance, but the influence of psychophysiological mechanisms on ergogenic effects is not yet understood. OBJECTIVE: This study retrospectively examined whether changes in TTE cycling performance are mediated by positive expectations of receiving NaHCO3 and/or the decline in blood bicarbonate during exercise. METHODS: In a randomised, crossover, counterbalanced, double-blind, placebo-controlled design, 12 recreationally trained cyclists (maximal oxygen consumption, 54.4 ± 5.7 mL·kg·min-1) performed four TTE cycling tests 90 min after consuming: (1) 0.3 g·kg-1 body mass NaHCO3 in 5 mL·kg-1 body mass solution, (2) 0.03 g·kg-1 body mass sodium chloride in solution (placebo), (3) 0.3 g·kg-1 body mass NaHCO3 in capsules and (4) cornflour in capsules (placebo). Prior to exercise, participants rated on 1-5 Likert type scales how much they expected the treatment they believe had been given would improve performance. Capillary blood samples were measured for acid-base balance at baseline, pre-exercise and post-exercise. RESULTS: Administering NaHCO3 in solution and capsules improved TTE compared with their respective placebos (solution: 27.0 ± 21.9 s, p = 0.001; capsules: 23.0 ± 28.1 s, p = 0.016). Compared to capsules, NaHCO3 administered via solution resulted in a higher expectancy about the benefits on TTE cycling performance (Median: 3.5 vs. 2.5, Z = 2.135, p = 0.033). Decline in blood bicarbonate during exercise was higher for NaHCO3 given in solution compared to capsules (2.7 ± 2.1 mmol·L-1, p = 0.001). Mediation analyses showed that improvements in TTE cycling were indirectly related to expectancy and decline in blood bicarbonate when NaHCO3 was administered in solution but not capsules. CONCLUSIONS: Participants' higher expectations when NaHCO3 is administered in solution could result in them exerting themselves harder during TTE cycling, which subsequently leads to a greater decline in blood bicarbonate and larger improvements in performance. KEY POINTS: Ingesting 0.3 g·kg-1 body mass sodium bicarbonate in solution and capsules improved time-to-exhaustion cycling performance Positive expectancy about the benefits of sodium bicarbonate and decline in blood bicarbonate were higher when sodium bicarbonate was administered in solution compared with capsules Improvements in time-to-exhaustion cycling performance for sodium bicarbonate administered in solution were related to expectancy and the enhanced extracellular buffering response.

Outcomes of Aortobifemoral Bypass Based on Configuration of the Proximal Anastomosis.

BACKGROUND: Aortobifemoral bypass (ABF) remains an important treatment modality in the revascularization of aortoiliac occlusive disease. Despite ABF being performed for decades, questions remain regarding the preferred technique for the proximal anastomosis, specifically whether an end-to-end (EE) or an end-to-side (ES) configuration is superior. The goal of this study was to compare the outcomes of ABF based on proximal configuration. METHODS: We queried the Vascular Quality Initiative registry for ABF procedures performed between 2009 and 2020. Univariate and multivariate logistic regression analyses were used to compare perioperative and 1-year outcomes between EE and ES configurations. RESULTS: Of the 6,782 patients (median [interquartile range] age, 60.0 [54-66 years]) who underwent ABF, 3,524 (52%) had an EE proximal anastomosis and 3,258 (48%) had an ES proximal anastomosis. Postoperatively, the ES cohort had a higher frequency of extubation in the operating room (80.3% vs. 77.4%; P < 0.01), lower change in renal function (8.8% vs. 11.5%; P < 0.01), and lower use of vasopressors (15.6% vs. 19.1%; P < 0.01), but higher rates of unanticipated return to the operating room (10.2% vs. 8.7%; P = 0.037) compared with the EE configuration. At 1-year follow-up, the ES cohort had a significantly lower primary graft patency rate (87.5% vs. 90.2%; P < 0.01) and higher rates of graft revision (4.8% vs. 3.1%; P < 0.01) and claudication symptoms (11.6% vs. 9.9%; P < 0.01). The ES configuration was significantly associated with a higher rate of 1-year major limb amputations in univariate (1.6% vs. 0.9%; P < 0.01) and multivariate (odds ratio, 1.95, confidence interval, 1.18-3.23, P=<0.01) analyses. CONCLUSIONS: While the ES cohort seemed to have less physiologic insult immediately postoperatively, the EE configuration appeared to have improved 1-year outcomes. To our knowledge, this study is one of the largest population-based studies comparing the outcomes of the proximal anastomotic configurations. Longer-term follow-up is needed to determine which configuration is optimal.

The Use of Paclitaxel-Coated Devices in the Treatment of Peripheral Arterial Disease is Not Associated With Increased Mortality or Amputations.

BACKGROUND: Strategies for the most effective treatment for peripheral arterial disease (PAD) remain controversial among clinicians. Several trials have shown improved primary patency of femoropopliteal interventions with the utilization of paclitaxel-coated balloons or stents compared to conventional balloons or stents. However, a 2018 meta-analysis suggested an increased mortality risk for patients receiving drug-coated balloons or stents (DCBS), resulting in an international pause in the use of DCBS. A 2021 meta-analysis by the same group suggested an increased risk of major amputation following DCBS use in peripheral arterial revascularization procedures. Here we report our long-term institutional outcomes comparing uncoated devices to DCBS. METHODS: A retrospective review of all patients who underwent peripheral arterial angioplasty, stenting, atherectomy, or a combination between 2011 and 2020 within a regional healthcare system was performed. Univariate, multivariate, and survival analyses were performed using standard statistical methods to assess the primary end points of overall survival, 5-year survival, and amputation-free survival. RESULTS: A total of 2,717 patients were identified, of whom 1,965 were treated with conventional uncoated devices and 752 were treated with DCBS. A univariate analysis showed that patients treated with non-DCBS had higher rates of overall mortality, major amputations, and mortality at 1, 3, and 5 years. A multivariable analysis demonstrated that the use of conventional devices, age, diabetes, chronic kidney disease, myocardial infarction, transient ischemic attack, warfarin use, and atrial fibrillation all significantly increased the risk of 5-year mortality, overall mortality, and combined mortality and/or amputation. CONCLUSIONS: DCBS are not associated with increased mortality or worse amputation-free survival in this real-world cohort of patients treated for PAD. Our data suggest that mortality is more closely linked with pre-existing patient comorbidities rather than device selection at the time of revascularization.

Outcomes of operative and nonoperative management of blunt thoracic aortic injury.

OBJECTIVE: Although the current guidelines for the management of blunt traumatic aortic injury (BTAI) have recommended intervention for grade 2 injuries or higher, a national trend has occurred for aggressive endovascular treatment of low-grade BTAIs. Little is known about the natural history of grade 1 and 2 injuries treated nonoperatively. We hypothesized that most of these low-grade injuries would remain stable with nonoperative management. METHODS: We performed a review of BTAIs at a large referral level 1 trauma center from 2004 to 2020. The injuries were graded using a standard 1 to 4 scale. The outcomes of the nonoperative and thoracic endovascular aortic repair (TEVAR) management strategies were compared, including post-trauma morbidity, mortality, reinterventions, and lesion stability. RESULTS: A total of 176 patients with BTAIs and sufficient imaging studies and follow-up data available were identified during the study period, including 36 with grade 1, 24 with grade 2, 115 with grade 3, and 1 with a grade 4 injury. Of these 176 patients, 112 had undergone TEVAR and 64 had been treated nonoperatively. Most of the patients (90.2%) who had undergone TEVAR had had grade 3 injuries. Nonoperative management was performed for 97.2% of the grade 1 injuries and 62.5% of the grade 2 injuries. Endovascular reintervention after TEVAR was rare (2.7%). The rates of post-trauma morbidity within 30 days (stroke, 3.6% vs 3.1%; myocardial infarction/arrhythmia, 8.9% vs 1.6%; respiratory failure, 31.2% vs 28.1%; acute kidney injury, 9.8% vs 12.5%; urinary tract infection, 2.7% vs 4.8%; gastrointestinal bleeding, 3.6% vs 0.0%; pulmonary embolism, 10.9% vs 4.5%) and 1-year mortality after discharge (1.8% vs 3.1%) were comparable between the operative and nonoperative groups. The median follow-up was 1501 days (interquartile range [IQR], 475.6-2804 days) for the TEVAR group and 1170.5 days (IQR, 317-2173 days) for the nonoperative group. No lesion progression had occurred in the patients with low-grade (grade 1-2) injuries managed nonoperatively. Resolution of grade 1 and 2 injury had occurred in 20% of the patients at 30 days, which had improved to 44% at long-term follow-up. Fourteen patients with grade 3 injuries (12.2% of the grade 3 injuries in our series) were also observed and did not require future intervention. These patients had generally had smaller pseudoaneurysms with minimal periaortic hematoma. None of these 14 patients had experienced progression or rupture during follow-up (median, 454.5 days; IQR, 81-1199 days) using computed tomography. CONCLUSIONS: Nonoperative management of low-grade BTAIs did not result in long-term aortic complications or the need for reintervention. We found that grade 3 injuries with smaller pseudoaneurysms and minimal periaortic hematoma can be safely observed if the patients can be appropriately followed up. Thus, the indications for treatment of select grade 3 injuries merit further consideration.

Ozone for SARS-CoV-2 inactivation on surfaces and in liquid cell culture media.

This study evaluated the inactivation of SARS-CoV-2, the virus responsible for COVID-19, by ozone using virus grown in cell culture media either dried on surfaces (plastic, glass, stainless steel, copper, and coupons of ambulance seat and floor) or suspended in liquid. Treatment in liquid reduced SARS-CoV-2 at a rate of 0.92 ± 0.11 log10-reduction per ozone CT dose(mg min/L); where CT is ozone concentration times exposure time. On surface, the synergistic effect of CT and relative humidity (RH) was key to virus inactivation; the rate varied from 0.01 to 0.27 log10-reduction per ozone CT value(g min/m3) as RH varied from 17% to 70%. Depletion of ozone by competitive reactions with the medium constituents, mass transfer limiting the penetration of ozone to the bulk of the medium, and occlusion of the virus in dried matrix were postulated as potential mechanisms that reduce ozone efficacy. RH70% was found plausible since it provided the highest disinfection rate while being below the critical RH that promotes mould growth in buildings. In conclusion, through careful choice of (CT, RH), gaseous ozone is effective against SARS-CoV-2 and our results are of significance to a growing field where ozone is applied to control the spread of COVID-19.

An Evidence-Based Care Protocol Improves Outcomes and Decreases Cost in Pediatric Appendicitis.

BACKGROUND: Appendicitis is a common indication for urgent abdominal surgery in the pediatric population. The postoperative management varies significantly in time to discharge and cost of care. The objective of this study was to investigate whether implementation of an evidence-based protocol after an appendectomy would lead to decreased length of stay and cost of care. METHODS: In 2014 at the Children's Hospital of Pittsburgh, an initiative to develop an evidenced-based protocol to treat appendicitis was undertaken. A work group was formed of pediatric surgeons and other important personnel to determine best practices. Treatment pathways were created. Pathways differed with recommendation on postoperative antibiotic choice and duration, diet initiation, and discharge criteria. Data were prospectively gathered from all patients (ages 0-18 y) with acute appendicitis from January 2015 to December 2016. Primary outcomes were length of stay and cost of care. Secondary outcomes were surgical site infection, readmission rate, and duration of postoperative antibiotics. RESULTS: Among the 1289 patients, 481 patients were in the preprotocol cohort and 808 patients were in the postprotocol cohort. 27% of patients had an intraoperative diagnosis of complicated appendicitis. There was a significantly shorter length of stay in the postprotocol cohort (P < 0.001). Median costs for the whole cohort decreased 0.6% and 24.6% for patients with complicated appendicitis after protocol initiation (P < 0.01). CONCLUSIONS: This study has demonstrated that introduction of an evidence-based clinical care protocol for pediatric patients with appendicitis leads to shorter hospital stay and decreased hospital costs.

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) in Human Lung Microvascular Endothelial Cells Controls Oxidative Stress, Reactive Oxygen-Mediated Cell Signaling and Inflammatory Responses.

BACKGROUND: Perturbation of endothelial function in people with cystic fibrosis (CF) has been reported, which may be associated with endothelial cell expression of the cystic fibrosis transmembrane conductance regulator (CFTR). Previous reports indicate that CFTR activity upregulates endothelial barrier function, endothelial nitric oxide synthase (eNOS) expression and NO release, while limiting interleukin-8 (IL-8) release, in human umbilical vein endothelial cells (HUVECs) in cell culture. In view of reported microvascular dysfunction in people with CF we investigated the role of CFTR expression and activity in the regulation of oxidative stress, cell signaling and inflammation in human lung microvascular endothelial cells (HLMVECs) in cell culture. METHODS: HLMVECs were cultured in the absence and presence of the CFTR inhibitor GlyH-101 and CFTR siRNA. CFTR expression was analyzed using qRT-PCR, immunocytochemistry (IHC) and western blot, and function by membrane potential assay. IL-8 expression was analyzed using qRT-PCR and ELISA. Nrf2 expression, and NF-κB and AP-1 activation were determined using IHC and western blot. The role of the epidermal growth factor receptor (EGFR) in CFTR signaling was investigated using the EGFR tyrosine kinase inhibitor AG1478. Oxidative stress was measured as intracellular ROS and hydrogen peroxide (H2O2) concentration. VEGF and SOD-2 were measured in culture supernatants by ELISA. RESULTS: HLMVECs express low levels of CFTR that increase following inhibition of CFTR activity. Inhibition of CFTR, significantly increased intracellular ROS and H2O2 levels over 30 min and significantly decreased Nrf2 expression by 70% while increasing SOD-2 expression over 24 h. CFTR siRNA significantly increased constitutive expression of IL-8 by HLMVECs. CFTR inhibition activated the AP-1 pathway and increased IL-8 expression, without effect on NF-κB activity. Conversely, TNF-α activated the NF-κB pathway and increased IL-8 expression. The effects of TNF-α and GlyH-101 on IL-8 expression were additive and inhibited by AG1478. Inhibition of both CFTR and EGFR in HLMVECs significantly increased VEGF expression. The antioxidant N-acetyl cysteine significantly reduced ROS production and the increase in IL-8 and VEGF expression following CFTR inhibition. CONCLUSION: Functional endothelial CFTR limits oxidative stress and contributes to the normal anti-inflammatory state of HLMVECs. Therapeutic strategies to restore endothelial CFTR function in CF are warranted.

TOK channels use the two gates in classical K+ channels to achieve outward rectification.

TOKs are outwardly rectifying K+ channels in fungi with two pore-loops and eight transmembrane spans. Here, we describe the TOKs from four pathogens that cause the majority of life-threatening fungal infections in humans. These TOKs pass large currents only in the outward direction like the canonical isolate from Saccharomyces cerevisiae (ScTOK), and distinct from other K+ channels. ScTOK, AfTOK1 (Aspergillus fumigatus), and H99TOK (Cryptococcus neoformans grubii) are K+ -selective and pass current above the K+ reversal potential. CaTOK (Candida albicans) and CnTOK (Cryptococcus neoformans neoformans) pass both K+ and Na+ and conduct above a reversal potential reflecting the mixed permeability of their selectivity filter. Mutations in CaTOK and ScTOK at sites homologous to those that open the internal gates in classical K+ channels are shown to produce inward TOK currents. A favored model for outward rectification is proposed whereby the reversal potential determines ion occupancy, and thus, conductivity, of the selectivity filter gate that is coupled to an imperfectly restrictive internal gate, permitting the filter to sample ion concentrations on both sides of the membrane.

Spadin Selectively Antagonizes Arachidonic Acid Activation of TREK-1 Channels.

TREK-1 channel activity is a critical regulator of neuronal, cardiac, and smooth muscle physiology and pathology. The antidepressant peptide, spadin, has been proposed to be a TREK-1-specific blocker. Here we sought to examine the mechanism of action underlying spadin inhibition of TREK-1 channels. Heterologous expression in Xenopus laevis oocytes and electrophysiological analysis using two-electrode voltage clamp in standard bath solutions was used to characterize the pharmacological profile of wild-type and mutant murine TREK-1 and TREK-2 channels using previously established human K2P activators; arachidonic acid (AA), cis-4,7,10,13,16,19-docosahexaenoic acid (DHA), BL-1249, and cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC) and inhibitors; spadin and barium (Ba2+). Mouse TREK-1 and TREK-2 channel currents were both significantly increased by AA, BL-1249, and CDC, similar to their human homologs. Under basal conditions, both TREK-1 and TREK-2 currents were insensitive to application of spadin, but could be blocked by Ba2+. Spadin did not significantly inhibit either TREK-1 or TREK-2 currents either chemically activated by AA, BL-1249, or CDC, or structurally activated via a gating mutation. However, pre-exposure to spadin significantly perturbed the subsequent activation of TREK-1 currents by AA, but not TREK-2. Furthermore, spadin was unable to prevent activation of TREK-1 by BL-1249, CDC, or the related bioactive lipid, DHA. Spadin specifically antagonizes the activation of TREK-1 channels by AA, likely via an allosteric mechanism. Lack of intrinsic activity may explain the absence of clinical side effects during antidepressant therapy.

A critical role for the inward rectifying potassium channel Kir7.1 in oligodendrocytes of the mouse optic nerve.

Inward rectifying potassium channels (Kir) are a large family of ion channels that play key roles in ion homeostasis in oligodendrocytes, the myelinating cells of the central nervous system (CNS). Prominent expression of Kir4.1 has been indicated in oligodendrocytes, but the extent of expression of other Kir subtypes is unclear. Here, we used qRT-PCR to determine expression of Kir channel transcripts in the mouse optic nerve, a white matter tract comprising myelinated axons and the glia that support them. A novel finding was the high relative expression of Kir7.1, comparable to that of Kir4.1, the main glial Kir channel. Significantly, Kir7.1 immunofluorescence labelling in optic nerve sections and in isolated cells was localised to oligodendrocyte somata. Kir7.1 are known as a K+ transporting channels and, using patch clamp electrophysiology and the Kir7.1 blocker VU590, we demonstrated Kir7.1 channels carry a significant proportion of the whole cell potassium conductance in oligodendrocytes isolated from mouse optic nerves. Notably, oligodendrocytes are highly susceptible to ischemia/hypoxia and this is due at least in part to disruption of ion homeostasis. A key finding of this study is that blockade of Kir7.1 with VU590 compromised oligodendrocyte cell integrity and compounds oligodendroglial loss in ischemia/hypoxia in the oxygen-glucose deprivation (OGD) model in isolated intact optic nerves. These data reveal Kir7.1 channels are molecularly and functionally expressed in oligodendrocytes and play an important role in determining oligodendrocyte survival and myelin integrity.

Frontline Science: Rev-Erbα links blue light with enhanced bacterial clearance and improved survival in murine Klebsiella pneumoniae pneumonia.

The wavelength of light is a critical determinant of light's capacity to entrain adaptive biological mechanisms, such as enhanced immune surveillance, that precede and prepare us for the active circadian day, a time when the risk of encountering pathogen is highest. Light rich in the shorter wavelength visible blue spectrum maximally entrains these circadian rhythms. We hypothesized that exposure to blue light during sepsis will augment immunity and improve outcome. Using a clinically relevant Klebsiella pneumoniae acute lower respiratory tract infection model, we show that blue spectrum light shifts autonomic tone toward parasympathetic predominance and enhances immune competence, as characterized by accelerated pathogen clearance that is accompanied by reduced alveolar neutrophil influx, inflammation, and improved survival. Blue light functioned through an optic-cholinergic pathway and expansion of splenic Ccr2+ monocytes to increase control of the infection and improve survival. The "keystone" mediating these effects is the circadian clock protein Rev-Erbα, and biochemical activation with Rev-Erbα agonist SR9009 enhanced mononuclear cell phagocytosis in vitro and recapitulated the enhanced pathogen elimination in vivo observed with blue light. These findings underscore the potential therapeutic value of blue light and modulating Rev-Erbα to enhance host immunity against infection.

Murine sepsis phenotypes and differential treatment effects in a randomized trial of prompt antibiotics and fluids.

BACKGROUND: Clinical and biologic phenotypes of sepsis are proposed in human studies, yet it is unknown whether prognostic or drug response phenotypes are present in animal models of sepsis. Using a biotelemetry-enhanced, murine cecal ligation and puncture (CLP) model, we determined phenotypes of polymicrobial sepsis prior to physiologic deterioration, and the association between phenotypes and outcome in a randomized trial of prompt or delayed antibiotics and fluids. METHODS: We performed a secondary analysis of male C57BL/6J mice in two observational cohorts and two randomized, laboratory animal experimental trials. In cohort 1, mice (n = 118) underwent biotelemetry-enhanced CLP, and we applied latent class mixed models to determine optimal number of phenotypes using clinical data collected between injury and physiologic deterioration. In cohort 2 (N = 73 mice), inflammatory cytokines measured at 24 h after deterioration were explored by phenotype. In a subset of 46 mice enrolled in two trials from cohort 1, we tested the association of phenotypes with the response to immediate (0 h) vs. delayed (2 to 4 h) antibiotics or fluids initiated after physiologic deterioration. RESULTS: Latent class mixture modeling derived a two-class model in cohort 1. Class 2 (N = 97) demonstrated a shorter time to deterioration (mean SD 7.3 (0.9) vs. 9.7 (3.2) h, p < 0.001) and lower heart rate at 7 h after injury (mean (SD) 564 (55) vs. 626 (35) beats per minute, p < 0.001). Overall mortality was similar between phenotypes (p = 0.75). In cohort 2 used for biomarker measurement, class 2 mice had greater plasma concentrations of IL6 and IL10 at 24 h after CLP (p = 0.05). In pilot randomized trials, the effects of sepsis treatment (immediate vs. delayed antibiotics) differed by phenotype (p = 0.03), with immediate treatment associated with greater survival in class 2 mice only. Similar differential treatment effect by class was observed in the trial of immediate vs. delayed fluids (p = 0.02). CONCLUSIONS: We identified two sepsis phenotypes in a murine cecal ligation and puncture model, one of which is characterized by faster deterioration and more severe inflammation. Response to treatment in a randomized trial of immediate versus delayed antibiotics and fluids differed on the basis of phenotype.

Glial and neuronal expression of the Inward Rectifying Potassium Channel Kir7.1 in the adult mouse brain.

Inward Rectifying Potassium channels (Kir) are a large family of ion channels that play key roles in ion homeostasis and neuronal excitability. The most recently described Kir subtype is Kir7.1, which is known as a K+ transporting subtype. Earlier studies localised Kir7.1 to subpopulations of neurones in the brain. However, the pattern of Kir7.1 expression across the brain has not previously been examined. Here, we have determined neuronal and glial expression of Kir7.1 in the adult mouse brain, using immunohistochemistry and transgenic mouse lines expressing reporters specific for astrocytes [glial fibrillary acidic protein-enhanced green fluorescent protein (GFAP-EGFP], myelinating oligodendrocytes (PLP-DsRed), oligodendrocyte progenitor cells (OPC, Pdgfra-creERT2 /Rosa26-YFP double-transgenic mice) and all oligodendrocyte lineage cells (SOX10-EGFP). The results demonstrate significant neuronal Kir7.1 immunostaining in the cortex, hippocampus, cerebellum and pons, as well as the striatum and hypothalamus. In addition, astrocytes are shown to be immunopositive for Kir7.1 throughout grey and white matter, with dense immunostaining on cell somata, primary processes and perivascular end-feet. Immunostaining for Kir7.1 was observed in oligodendrocytes, myelin and OPCs throughout the brain, although immunostaining was heterogeneous. Neuronal and glial expression of Kir7.1 is confirmed using neurone-glial cortical cultures and optic nerve glial cultures. Notably, Kir7.1 have been shown to regulate the excitability of thalamic neurones and our results indicate this may be a widespread function of Kir7.1 in neurones throughout the brain. Moreover, based on the function of Kir7.1 in multiple transporting epithelia, Kir7.1 are likely to play an equivalent role in the primary glial function of K+ homeostasis. Our results indicate Kir7.1 are far more pervasive in the brain than previously recognised and have potential importance in regulating neuronal and glial function.

A Novel Ingestion Strategy for Sodium Bicarbonate Supplementation in a Delayed-Release Form: a Randomised Crossover Study in Trained Males.

BACKGROUND: Sodium bicarbonate (NaHCO3) is a well-established nutritional ergogenic aid, though gastrointestinal (GI) distress is a common side-effect. Delayed-release NaHCO3 may alleviate GI symptoms and enhance bicarbonate bioavailability following oral ingestion, although this has yet to be confirmed. METHODS: In a randomised crossover design, pharmacokinetic responses and acid-base status were compared following two forms of NaHCO3, as were GI symptoms. Twelve trained healthy males (mean ± SD age 25.8 ± 4.5 years, maximal oxygen uptake ([Formula: see text]) 58.9 ± 10.9 mL kg min-1, height 1.8 ± 0.1 m, body mass 82.3 ± 11.1 kg, fat-free mass 72.3 ± 10.0 kg) underwent a control (CON) condition and two experimental conditions: 300 mg kg-1 body mass NaHCO3 ingested as an aqueous solution (SOL) and encased in delayed-release capsules (CAP). Blood bicarbonate concentration, pH and base excess (BE) were measured in all conditions over 180 min, as were subjective GI symptom scores. RESULTS: Incidences of GI symptoms and overall severity were significantly lower (mean difference = 45.1%, P < 0.0005 and 47.5%, P < 0.0005 for incidences and severity, respectively) with the CAP than with the SOL. Symptoms displayed increases at 40 to 80 min post-ingestion with the SOL that were negated with CAP (P < 0.05). Time to reach peak bicarbonate concentration, pH and BE were significantly longer with CAP than with the SOL. CONCLUSIONS: In summary, CAP can mitigate GI symptoms induced with SOL and should be ingested earlier to induce similar acid-base changes. Furthermore, CAP may be more ergogenic in those who experience severe GI distress with SOL, although this warrants further investigation.

The influence of alkalosis on repeated high-intensity exercise performance and acid-base balance recovery in acute moderate hypoxic conditions.

PURPOSE: Exacerbated hydrogen cation (H+) production is suggested to be a key determinant of fatigue in acute hypoxic conditions. This study, therefore, investigated the effects of NaHCO3 ingestion on repeated 4 km TT cycling performance and post-exercise acid-base balance recovery in acute moderate hypoxic conditions. METHODS: Ten male trained cyclists completed four repeats of 2 × 4 km cycling time trials (TT1 and TT2) with 40 min passive recovery, each on different days. Each TT series was preceded by supplementation of one of the 0.2 g kg-1 BM NaHCO3 (SBC2), 0.3 g kg-1 BM NaHCO3 (SBC3), or a taste-matched placebo (0.07 g kg-1 BM sodium chloride; PLA), administered in a randomized order. Supplements were administered at a pre-determined individual time to peak capillary blood bicarbonate concentration ([HCO3-]). Each TT series was also completed in a normobaric hypoxic chamber set at 14.5% FiO2 (~ 3000 m). RESULTS: Performance was improved following SBC3 in both TT1 (400.2 ± 24.1 vs. 405.9 ± 26.0 s; p = 0.03) and TT2 (407.2 ± 29.2 vs. 413.2 ± 30.8 s; p = 0.01) compared to PLA, displaying a very likely benefit in each bout. Compared to SBC2, a likely and possible benefit was also observed following SBC3 in TT1 (402.3 ± 26.5 s; p = 0.15) and TT2 (410.3 ± 30.8 s; p = 0.44), respectively. One participant displayed an ergolytic effect following SBC3, likely because of severe gastrointestinal discomfort, as SBC2 still provided ergogenic effects. CONCLUSION: NaHCO3 ingestion improves repeated exercise performance in acute hypoxic conditions, although the optimal dose is likely to be 0.3 g kg-1 BM.

Translational Sepsis Research: Spanning the Divide.

OBJECTIVE: Our knowledge of the molecular mechanisms of sepsis has attained exponential growth. Yet, the pillars of its care remain antibiotics, fluid resuscitation, and physiologic support of failing organ systems. The inability to bring biologic breakthroughs to the bedside is not for lack of effort. Over 60 clinical trials of novel therapies, each heavily supported by the momentum of biologic data suggesting clinical utility, have been conducted and have failed to identify benefit. This mass of "negative" clinical data abut an equally towering mound of knowledge of sepsis biology, which collectively have led investigators to ask, "what happened?" DATA SOURCES: Review of published scientific literature via MEDLINE searches using key terms related to the article topics. STUDY SELECTION: Original articles, review articles, and systematic reviews were considered. DATA EXTRACTION: Articles were selected for inclusion based upon author consensus. DATA SYNTHESIS: Here, we present a synthetic review of some of the challenges in translating experimental animal models of sepsis to the bedside. We commence with the concept that the heterogeneity in the kinetics of the sepsis response serves as an important, often underappreciated but surmountable, source of translational impedance. Upon this groundwork, we discuss distinctions between animal experimentation and clinical trial design in the elements for hypothesis testing: cohort selection, power and sample size, randomization and blinding, and timing of intervention. From this concept, we develop a contextual framework for advancing the paradigm of animal-based investigations to facilitate science that transitions from molecule to medicine. CONCLUSIONS: A persistent divide exists between the laboratory and clinical research arenas, which may be addressable via systematic targeting of identified translational gaps.

Blue Light Enhances Bacterial Clearance and Reduces Organ Injury During Sepsis.

OBJECTIVES: The physiology of nearly all mammalian organisms are entrained by light and exhibit circadian rhythm. The data derived from animal studies show that light influences immunity, and these neurophysiologic pathways are maximally entrained by the blue spectrum. Here, we hypothesize that bright blue light reduces acute kidney injury by comparison with either bright red or standard, white fluorescent light in mice subjected to sepsis. To further translational relevance, we performed a pilot clinical trial of blue light therapy in human subjects with appendicitis. DESIGN: Laboratory animal research, pilot human feasibility trial. SETTING: University basic science laboratory and tertiary care hospital. SUBJECTS: Male C57BL/6J mice, adult (> 17 yr) patients with acute appendicitis. INTERVENTIONS: Mice underwent cecal ligation and puncture and were randomly assigned to a 24-hour photoperiod of bright blue, bright red, or ambient white fluorescent light. Subjects with appendicitis were randomized to receive postoperatively standard care or standard care plus high-illuminance blue light. MEASUREMENTS AND MAIN RESULTS: Exposure to bright blue light enhanced bacterial clearance from the peritoneum, reduced bacteremia and systemic inflammation, and attenuated the degree of acute kidney injury. The mechanism involved an elevation in cholinergic tone that augmented tissue expression of the nuclear orphan receptor REV-ERBα and occurred independent of alterations in melatonin or corticosterone concentrations. Clinically, exposure to blue light after appendectomy was feasible and reduced serum interleukin-6 and interleukin-10 concentrations. CONCLUSIONS: Modifying the spectrum of light may offer therapeutic utility in sepsis.

TREK-1 Channel Expression in Smooth Muscle as a Target for Regulating Murine Intestinal Contractility: Therapeutic Implications for Motility Disorders.

Gastrointestinal (GI) motility disorders such as irritable bowel syndrome (IBS) can occur when coordinated smooth muscle contractility is disrupted. Potassium (K+) channels regulate GI smooth muscle tone and are key to GI tract relaxation, but their molecular and functional phenotypes are poorly described. Here we define the expression and functional roles of mechano-gated K2P channels in mouse ileum and colon. Expression and distribution of the K2P channel family were investigated using quantitative RT-PCR (qPCR), immunohistochemistry and confocal microscopy. The contribution of mechano-gated K2P channels to mouse intestinal muscle tension was studied pharmacologically using organ bath. Multiple K2P gene transcripts were detected in mouse ileum and colon whole tissue preparations. Immunohistochemistry confirmed TREK-1 expression was smooth muscle specific in both ileum and colon, whereas TREK-2 and TRAAK channels were detected in enteric neurons but not smooth muscle. In organ bath, mechano-gated K2P channel activators (Riluzole, BL-1249, flufenamic acid, and cinnamyl 1-3,4-dihydroxy-alpha-cyanocinnamate) induced relaxation of KCl and CCh pre-contracted ileum and colon tissues and reduced the amplitude of spontaneous contractions. These data reveal the specific expression of mechano-gated K2P channels in mouse ileum and colon tissues and highlight TREK-1, a smooth muscle specific K2P channel in GI tract, as a potential therapeutic target for combating motility pathologies arising from hyper-contractility.