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Rationale: We hypothesized that platelet-neutrophil interactions occur as a result of acute carbon monoxide (CO) poisoning, and subsequent neutrophil activation triggers events that cause neurologic sequelae.Objectives: To identify platelet-neutrophil interactions and neutrophil activation in patients and in animal models, and to establish the association between these intravascular events and changes linked to CO-mediated neurologic sequelae in an animal model.Measurements and Main Results: Blood was obtained from 50 consecutive patients. Abnormalities were variable depending on the carboxyhemoglobin level at study admission and duration of CO exposure. Platelet-neutrophil aggregates were detected and plasma myeloperoxidase (MPO) concentration was significantly elevated in those with confirmed CO poisoning. Among patients exposed to CO for over 3 h, flow cytometry scans of neutrophils revealed increased surface expression of CD18 and, in some groups, MPO on the cell surface. Animal models revealed consistent evidence of platelet-neutrophil aggregates, neutrophil activation and surface MPO, and plasma MPO elevation. MPO was deposited along the brain vascular lining and colocalized with nitrotyrosine. CO poisoning caused abnormalities in the charge pattern of myelin basic protein (MBP), changes linked to adaptive immunologic responses responsible for neurologic sequelae in this model. Changes did not occur in thrombocytopenic rats, those receiving tirofiban to inhibit platelet-neutrophil interactions, or those receiving L-nitroarginine methyl ester to inhibit nitric oxide synthesis. Alterations in MBP did not occur in CO-poisoned knockout mice lacking MPO.Conclusions: Acute CO poisoning causes intravascular neutrophil activation due to interactions with platelets. MPO liberated by neutrophils mediates perivascular oxidative stress, which is linked to immune-mediated neurologic sequelae. [ABSTRACT FROM AUTHOR]

This article examines obligatory backward resumption in Karuk (kyh; isolate), a verb-final language of Northern California, and argues that it is the result of conflicting word-order requirements. This conceptual analysis is further developed within the chain-resolution framework of Landau 2006, in which resumption is the result of partial deletion. The Karuk facts indicate that partial deletion targets spellout domains and not phases, contra van Urk 2018. Examination of two case studies from the literature and a reinterpretation of the Dinka resumption data discussed in van Urk 2018 further demonstrate that partial deletion of spellout domains has broader empirical coverage than partial deletion of phases. The second part of the article pivots to the predictions made by the chain-resolution analysis about alternatives to backward resumption. These predictions are shown to be borne out in three other verb-final languages, namely Hindi-Urdu, Persian, and Turkish. The article closes with an examination of the parallels between backward resumption and regular forward resumption and concludes that both may be derived by movement or by basegeneration of the proform. [ABSTRACT FROM AUTHOR]

Loss of plasma gelsolin (pGSN), a protein that lyses actin filaments, is implicated in the pathology of inflammatory and neurodegenerative diseases. We hypothesized that because pGSN is depleted in a murine model of decompression sickness (DCS), supplementation by administration of human recombinant (rhu-) pGSN would ameliorate inflammatory events. We observed that pGSN levels were persistently decreased in mice for at least 12 days post-exposure to 790 kPa of air for 2 hours. This decline was associated with elevated levels of inflammatory microparticles (MPs) in the blood and cervical lymph nodes, which previously were shown to cause neuroinflammation. Additionally, these mice exhibited reduced expression of synaptic proteins, impaired neurogenesis as well as impaired cognitive and motor functions. Rhu-pGSN ameliorated the inflammatory changes and resulted in restored synaptic protein expression, neurogenesis and neurological function. These findings demonstrate that neuronal dysfunction in our murine model of DCS is mediated by MPs and that rhu-pGSN can ameliorate injury even when administered in a delayed fashion.

Carbon monoxide (CO) is a relatively frequent cause of poisoning evaluated in emergency departments. The risk of neurologic injuries, such as cognitive, psychological, vestibular, and motor deficits, is 25% to 50%. However, the risk of cardiac injuries should also be considered. Among patients with CO poisoning, the mortality in patients with myocardial injury is approximately 3 times greater than that in patients without myocardial injury. In large-scale studies, up to 69.2% of patients with acute CO poisoning exhibiting elevated troponin I levels and no underlying cardiovascular illnesses had late gadolinium enhancement on cardiac magnetic resonance, suggesting covert CO-induced myocardial fibrosis. Myocardial damage can be evaluated using electrocardiography, echocardiography, computed tomography, and cardiac magnetic resonance. This paper offers recommendations for cardiac evaluations based on our collective experience of managing >2,000 cases of acute CO poisoning with supporting information taken from peer-reviewed published reports on CO poisoning., Competing Interests: Funding Support and Author Disclosures This work was supported in part by the National Research Foundation of Korea, which is funded by the Korean government (Ministry of Science and Information and Communications Technology, grant number NRF-2021R1A2C200492211) and by a grant from the National Institutes of Health (National Institute of Neurological Disorders and Stroke) (R01-NS122855). The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and the decision to submit the manuscript for publication. The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

We hypothesized that early intra-central nervous system (CNS) responses in a murine model of decompression sickness (DCS) would be reflected by changes in the microparticles (MPs) that exit the brain via the glymphatic system, and due to systemic responses the MPs would cause inflammatory changes lasting for many days leading to functional neurological deficits. Elevations on the order of threefold of blood-borne inflammatory MPs, neutrophil activation, glymphatic flow, and neuroinflammation in cerebral cortex and hippocampus were found in mice at 12 days after exposure to 760 kPa of air for 2 h. Mice also exhibited a significant decline in memory and locomotor activity, as assessed by novel object recognition and rotarod testing. Similar inflammatory changes in blood, neuroinflammation, and functional impairments were initiated in naïve mice by injection of filamentous (F-) actin-positive MPs, but not F-actin-negative MPs, obtained from decompressed mice. We conclude that high pressure/decompression stress establishes a systemic inflammatory process that results in prolonged neuroinflammation and functional impairments in the mouse decompression model. NEW & NOTEWORTHY Elevated glymphatic flow due to astrocyte and microglial activation from high-pressure exposure triggers release of microparticles (MPs) to the circulation where neutrophil activation and production of filamentous (F)-actin expressing MPs result in a persistent feed-forward neuroinflammatory cycle and functional deficits lasting for at least 12 days.

A blood component analysis is an early step for evaluating inflammatory disorders, but it can be unfeasible in some settings. This pilot study assessed whether extracellular vesicle (EV) changes in perspiration are parallel to those occurring in blood as an alternative or complementary option to diagnose an inflammatory response. In parallel studies, EVs were analyzed in perspiration and blood obtained before and after five self-contained underwater breathing apparatus (SCUBA) divers at the National Aquarium in Baltimore performed a dive to 3.98 m of sea water for 40 min, and five non-divers performed an exercise routine at ambient atmospheric pressure. The results demonstrated that microparticles (MPs) are present in perspiration, their numbers increase in the blood in response to SCUBA diving, and the interleukin (IL)-1β content increases. In contrast, while blood-borne MPs became elevated in response to terrestrial exercise, no statistically significant increases occurred in perspiration, and there were no changes in IL-1β. There were no statistically significant elevations in the exosomes in perspiration or blood in response to SCUBA diving and few changes following terrestrial exercise. These findings suggest that an MP perspiration analysis could be a non-invasive method for detecting inflammatory responses that can occur due to the oxidative stress associated with SCUBA diving.

Objective: The goal of this investigation was to use comprehensive prediction modeling tools and available genetic information to try to improve upon the performance of simple clinical models in predicting whether a diabetic foot ulcer (DFU) will heal. Approach: We utilized a cohort study ( n  = 206) that included clinical factors, measurements of circulating endothelial precursor cells (CEPCs), and fine sequencing of the NOS1AP gene. We derived and selected relevant predictive features from this patient-level information using statistical and machine learning techniques. We then developed prognostic models using machine learning approaches and assessed predictive performance. The presentation is consistent with TRIPOD requirements. Results: Models using baseline clinical and CEPC data had an area under the receiver operating characteristic curve (AUC) of 0.73 (0.66-0.80). Models using only single nucleotide polymorphisms (SNPs) of the NOS1AP gene had an AUC of 0.67 (95% confidence interval, CI: [0.59-0.75]). However, models incorporating baseline and SNP information resulted in improved AUC (0.80, 95% CI [0.73-0.87]). Innovation: We provide a rigorous analysis demonstrating the predictive potential of genetic information in DFU healing. In this process, we present a framework for using advanced statistical and bioinformatics techniques for creating superior prognostic models and identify potentially predictive SNPs for future research. Conclusion: We have developed a new benchmark for which future predictive models can be compared against. Such models will enable wound care experts to more accurately predict whether a patient will heal and aid clinical trialists in designing studies to evaluate therapies for subjects likely or unlikely to heal.

Conventional dogma suggests that decompression sickness (DCS) is caused by nitrogen bubble nucleation in the blood vessels and/or tissues; however, the abundance of bubbles does not correlate with DCS severity. Since immune cells respond to chemical and environmental cues, we hypothesized that the elevated partial pressures of dissolved gases drive aberrant immune cell phenotypes in the alveolar vasculature. To test this hypothesis, we measured immune responses within human lung-on-a-chip devices established with primary alveolar cells and microvascular cells. Devices were pressurized to 1.0 or 3.5 atm and surrounded by normal alveolar air or oxygen-reduced air. Phenotyping of neutrophils, monocytes, and dendritic cells as well as multiplexed ELISA revealed that immune responses occur within 1 h and that normal alveolar air (i.e., hyperbaric oxygen and nitrogen) confer greater immune activation. This work strongly suggests innate immune cell reactions initiated at elevated partial pressures contribute to the etiology of DCS., Competing Interests: The authors declare no conflict of interest., (© 2024 The Authors. Bioengineering & Translational Medicine published by Wiley Periodicals LLC on behalf of American Institute of Chemical Engineers.)

Blood-borne extracellular vesicles and inflammatory mediators were evaluated in divers using a closed circuit rebreathing apparatus and custom-mixed gases to diminish some diving risks. "Deep" divers ( n = 8) dove once to mean (±SD) 102.5 ± 1.2 m of sea water (msw) for 167.3 ± 11.5 min. "Shallow" divers ( n = 6) dove 3 times on day 1, and then repetitively over 7 days to 16.4 ± 3.7 msw, for 49.9 ± 11.9 min. There were statistically significant elevations of microparticles (MPs) in deep divers (day 1) and shallow divers at day 7 that expressed proteins specific to microglia, neutrophils, platelets, and endothelial cells, as well as thrombospondin (TSP)-1 and filamentous (F-) actin. Intra-MP IL-1β increased by 7.5-fold ( p < 0.001) after day 1 and 41-fold ( p = 0.003) at day 7. Intra-MP nitric oxide synthase-2 (NOS2) increased 17-fold ( p < 0.001) after day 1 and 19-fold ( p = 0.002) at day 7. Plasma gelsolin (pGSN) levels decreased by 73% ( p < 0.001) in deep divers (day 1) and 37% in shallow divers by day 7. Plasma samples containing exosomes and other lipophilic particles increased from 186% to 490% among the divers but contained no IL-1β or NOS2. We conclude that diving triggers inflammatory events, even when controlling for hyperoxia, and many are not proportional to the depth of diving.

This short review addresses the mechanisms of injury mediated by carbon monoxide (CO) and current information on efficacy of hyperbaric oxygen therapy (HBOT). Recent clinical series involving large, country-wide databases and prospective randomized trials are summarized. We conclude that there is an abundance of basic science and preclinical and clinical research supporting the use of HBOT for acute CO poisoning. With appropriate consideration for pathology and therapeutic mechanisms, HBOT at a dose of 2.5-3.0 atm absolute is a necessary treatment for this toxidrome., (© 2022 British Pharmacological Society.)

This project investigated glial-based lymphatic (glymphatic) function and its role in a murine model of decompression sickness (DCS). DCS pathophysiology is traditionally viewed as being related to gas bubble formation from insoluble gas on decompression. However, a body of work implicates a role for a subset of inflammatory extracellular vesicles, 0.1 to 1 µm microparticles (MPs) that are elevated in human and rodent models in response to high gas pressure and rise further after decompression. Herein, we describe immunohistochemical and Western blot evidence showing that following high air pressure exposure, there are elevations of astrocyte NF-κB and microglial-ionized calcium-binding adaptor protein-1 (IBA-1) along with fluorescence contrast and MRI findings of an increase in glymphatic flow. Concomitant elevations of central nervous system-derived MPs coexpressing thrombospondin-1 (TSP) drain to deep cervical nodes and then to blood where they cause neutrophil activation. A new set of blood-borne MPs are generated that express filamentous actin at the surface that exacerbate neutrophil activation. Blood-brain barrier integrity is disrupted due to activated neutrophil sequestration that causes further astrocyte and microglial perturbation. When postdecompression node or blood MPs are injected into naïve mice, the same spectrum of abnormalities occur and they are blocked with coadministration of antibody to TSP. We conclude that high pressure/decompression causes neuroinflammation with an increased glymphatic flow. The resulting systemic liberation of TSP-expressing MPs sustains the neuroinflammatory cycle lasting for days. NEW & NOTEWORTHY A murine model of central nervous system (CNS) decompression sickness demonstrates that high gas pressure activates astrocytes and microglia triggering inflammatory microparticle (MP) production. Thrombospondin-expressing MPs are released from the CNS via enhanced glymphatic flow to the systemic circulation where they activate neutrophils. Secondary production of neutrophil-derived MPs causes further cell activation and neutrophil adherence to the brain microvasculature establishing a feed-forward neuroinflammatory cycle.

The proinflammatory state associated with diabetes mellitus (DM) remains poorly understood. We found patients with DM have 3- to 14-fold elevations of blood-borne microparticles (MPs) that bind phalloidin (Ph; Ph positive [+] MPs), indicating the presence of F-actin on their surface. We hypothesized that F-actin-coated MPs were an unrecognized cause for DM-associated proinflammatory status. Ph+MPs, but not Ph-negative MPs, activate human and murine (Mus musculus) neutrophils through biophysical attributes of F-actin and membrane expression of phosphatidylserine (PS). Neutrophils respond to Ph+MPs via a linked membrane array, including the receptor for advanced glycation end products and CD36, PS-binding membrane receptors. These proteins in conjunction with TLR4 are coupled to NO synthase 1 adaptor protein (NOS1AP). Neutrophil activation occurs because of Ph+MPs causing elevations of NF-κB and Src kinase (SrcK) via a concurrent increased association of NO synthase 2 and SrcK with NOS1AP, resulting in SrcK S-nitrosylation. We conclude that NOS1AP links PS-binding receptors with intracellular regulatory proteins. Ph+MPs are alarmins present in normal human plasma and are increased in those with DM and especially those with DM and a lower-extremity ulcer., (Copyright © 2023 The Authors.)

The goal of this multicentre study was to evaluate whether circulating endothelial precursor cells and microparticles can predict diabetic foot ulcer healing by the 16th week of care. We enrolled 207 subjects, and 40.0% (28.4, 41.5) healed by the 16th week of care. Using flow cytometry analysis, several circulating endothelial precursor cells measured at the first week of care were associated with healing after adjustment for wound area and wound duration. For example, CD34 + CD45 dim , the univariate odds ratio was 1.19 (95% confidence interval: 0.88, 1.61) and after adjustment for wound area and wound duration, the odds ratio was (1.67 (1.16, 2.42) p = 0.006). A prognostic model using CD34 + CD45 dim , wound area, and wound duration had an area under the curve of 0.75 (0.67, 0.82) and CD34 + CD45 dim per initial wound area, an area under the curve of 0.72 (0.64, 0.79). Microparticles were not associated with a healed wound. Previous studies have indicated that circulating endothelial precursor cells measured at the first office visit are associated with a healed diabetic foot ulcer. In this multicentred prospective study, we confirm this finding, show the importance of adjusting circulating endothelial precursor cells measurements by wound area, and show circulating endothelial precursor cells per wound area is highly predictive of a healed diabetic foot ulcer by 16th week of care., (© 2022 The Wound Healing Society.)

Oxygen is a powerful trigger for cellular reactions, but there are few comparative investigations assessing the effects over a large range of partial pressures. We investigated a metabolic response to single exposures to either normobaric (10%, 15%, 30%, 100%) or hyperbaric (1.4 ATA, 2.5 ATA) oxygen. Forty-eight healthy subjects (32 males/16 females; age: 43.7 ± 13.4 years, height: 172.7 ± 10.07 cm; weight 68.4 ± 15.7 kg) were randomly assigned, and blood samples were taken before and 2 h after each exposure. Microparticles (MPs) expressing proteins specific to different cells were analyzed, including platelets (CD41), neutrophils (CD66b), endothelial cells (CD146), and microglia (TMEM). Phalloidin binding and thrombospondin-1 (TSP), which are related to neutrophil and platelet activation, respectively, were also analyzed. The responses were found to be different and sometimes opposite. Significant elevations were identified for MPs expressing CD41, CD66b, TMEM, and phalloidin binding in all conditions but for 1.4 ATA, which elicited significant decreases. Few changes were found for CD146 and TSP. Regarding OPB, further investigation is needed to fully understand the future applications of such findings.

Diabetic foot ulcers (DFU) are a critical problem for those with diabetes mellitus. Predicting the healing likelihood of a DFU is important to implementing appropriate care, allocating resources, having access to advanced therapies, having successful clinical trials, calibrating clinical trial results, and providing information to administrative entities on patient and provider outcomes. Prognostic modelling can also be important when attempting to compare results across trials or care centres. In a prospective cohort study, we demonstrate and replicate that simple wound characteristics like wound area and wound duration can be used to predict wound healing by the 16th week of care. The models were based on previous literature and replicated using a machine learning algorithm. The use of wound duration and wound area in a prognostic model continues to be important when comparing study results, centre-based outcomes, as well as designing clinical trials., (© 2022 The Wound Healing Society.)

Background/objective: This case series pilot study assessed the effects of hyperbaric oxygen therapy (HBO2) for treating rheumatoid arthritis (RA)., Methods: Ten RA subjects received 30 HBO2 treatments over 6 to 10 weeks. Serial rheumatologic evaluations (ie, the Disease Activity Scale [DAS28], the Routine Assessment of Patient Index Data 3, and the Pain and Sleep Quality Questionnaire) were completed at baseline, throughout the course of the study, and at the 6-month follow-up., Results: There was a statistically significant effect of HBO2 therapy over time on the DAS28-Global Health (p = 0.01), the DAS28-C-reactive protein (p = 0.002), and the DAS28-erythrocyte sedimentation rate (p = 0.008) measures; these analyses excluded 2 patients who were in clinical remission at baseline. Selected post hoc comparisons showed significantly lower DAS28-Global Health, DAS28-C-reactive protein, and DAS28-erythrocyte sedimentation rate scores at 3 and 6 months relative to baseline. In addition, statistically significant decreases in pain as measured by the Routine Assessment of Patient Index Data 3 and Pain and Sleep Quality Questionnaire were observed at the end of HBO2 relative to baseline., Conclusions: Hyperbaric oxygen therapy is effective for joint pain in patients with RA based on data from multiple, validated clinical measures. Further research with more subjects and the use of a control group is necessary., Competing Interests: The authors declare no conflict of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

We hypothesized that carbon monoxide (CO) establishes an inflammatory cycle mediated by microparticles (MPs). Mice exposed to a CO protocol (1000 ​ppm for 40 ​min and then 3000 ​ppm for 20 ​min) that causes neuroinflammation exhibit NF-κB activation in astrocytes leading to generation of MPs expressing thrombospondin-1(TSP-1) that collect in deep cervical lymph nodes draining the brain glymphatic system. TSP-1 bearing MPs gain access to the blood stream where they activate neutrophils to generate a new family of MPs, and also stimulate endothelial cells as documented by leakage of intravenous 2000 ​kDa dextran. At the brain microvasculature, neutrophil and MPs sequestration, and myeloperoxidase activity result in elevations of the p65 subunit of NF-κB, serine 536 phosphorylated p65, CD36, and loss of astrocyte aquaporin-4 that persist for at least 7 days. Knock-out mice lacking the CD36 membrane receptor are resistant to all CO inflammatory changes. Events triggered by CO are recapitulated in naïve wild type mice injected with cervical node MPs from CO-exposed mice, but not control mice. All MPs-mediated events are inhibited with a NF-κB inhibitor, a myeloperoxidase inhibitor, or anti-TSP-1 antibodies. We conclude that astrocyte-derived MPs expressing TSP-1 establish a feed-forward neuroinflammatory cycle involving endothelial CD36-to-astrocyte NF-κB crosstalk. As there is currently no treatment for CO-induced neurological sequelae, these findings pose several possible sites for therapeutic interventions., Competing Interests: The author(s) declare no competing interests., (© 2021 The Authors.)

Plasma gelsolin (pGSN) levels fall in association with diverse inflammatory conditions. We hypothesized that pGSN would decrease due to the stresses imposed by high pressure and subsequent decompression, and repletion would ameliorate injuries in a murine decompression sickness (DCS) model. Research subjects were found to exhibit a modest decrease in pGSN level while at high pressure and a profound decrease after decompression. Changes occurred concurrent with elevations of circulating microparticles (MPs) carrying interleukin (IL)-1β. Mice exhibited a comparable decrease in pGSN after decompression along with elevations of MPs carrying IL-1β. Infusion of recombinant human (rhu)-pGSN into mice before or after pressure exposure abrogated these changes and prevented capillary leak in brain and skeletal muscle. Human and murine MPs generated under high pressure exhibited surface filamentous actin (F-actin) to which pGSN binds, leading to particle lysis. In addition, human neutrophils exposed to high air pressure exhibit an increase in surface F-actin that is diminished by rhu-pGSN resulting in inhibition of MP production. Administration of rhu-pGSN may have benefit as prophylaxis or treatment for DCS. NEW & NOTEWORTHY Inflammatory microparticles released in response to high pressure and decompression express surface filamentous actin. Infusion of recombinant human plasma gelsolin lyses these particles in decompressed mice and ameliorates particle-associated vascular damage. Human neutrophils also respond to high pressure with an increase in surface filamentous actin and microparticle production, and these events are inhibited by plasma gelsolin. Gelsolin infusion may have benefit as prophylaxis or treatment for decompression sickness.

The SARS-Cov-2 (COVID-19) pandemic remains a major worldwide public health issue. Initially, improved supportive and anti-inflammatory intervention, often employing known drugs or technologies, provided measurable improvement in management. We have recently seen advances in specific therapeutic interventions and in vaccines. Nevertheless, it will be months before most of the world's population can be vaccinated to achieve herd immunity. In the interim, hyperbaric oxygen (HBO2) treatment offers several potentially beneficial therapeutic effects. Three small published series, one with a propensity-score-matched control group, have demonstrated safety and initial efficacy. Additional anecdotal reports are consistent with these publications. HBO2 delivers oxygen in extreme conditions of hypoxemia and tissue hypoxia, even in the presence of lung pathology. It provides anti-inflammatory and anti-proinflammatory effects likely to ameliorate the overexuberant immune response common to COVID-19. Unlike steroids, it exerts these effects without immune suppression. One study suggests HBO2 may reduce the hypercoagulability seen in COVID patients. Also, hyperbaric oxygen offers a likely successful intervention to address the oxygen debt expected to arise from a prolonged period of hypoxemia and tissue hypoxia. To date, 11 studies designed to investigate the impact of HBO2 on patients infected with SARS-Cov-2 have been posted on clinicaltrials.gov. This paper describes the promising physiologic and biochemical effects of hyperbaric oxygen in COVID-19 and potentially in other disorders with similar pathologic mechanisms., Competing Interests: The authors of this paper declare no conflicts of interest exist with this submission., (Copyright© Undersea and Hyperbaric Medical Society.)

The recent coronavirus disease 2019 (COVID-19) pandemic produced high and excessive demands for hospitalizations and equipment with depletion of critical care resources. The results of these extreme therapeutic efforts have been sobering. Further, we are months away from a robust vaccination effort, and current therapies provide limited clinical relief. Therefore, several empirical oxygenation support initiatives have been initiated with intermittent hyperbaric oxygen (HBO) therapy to overcome the unrelenting and progressive hypoxemia during maximum ventilator support in intubated patients, despite high FiO2. Overall, few patients have been successfully treated in different locations across the globe. More recently, less severe patients at the edge of impending hypoxemia were exposed to HBO preventing intubation and obtaining the rapid resolution of symptoms. The few case descriptions indicate large variability in protocols and exposure frequency. This summary illustrates the biological mechanisms of action of increased O 2 pressure, hoping to clarify more appropriate protocols and more useful application of HBO in COVID-19 treatment.

Background: Spinal injuries (SIs) can pose a significant burden to patients and family; delayed surgical intervention, associated with interhospital transfer, results in worse outcomes., Objective: This study aimed to identify early patient-centered factors associated with risk for near-shore SIs to assist clinicians with expeditious medical decision-making., Methods: We performed a multicenter retrospective study of all adults transported from Ocean City, Maryland to two emergency departments (EDs) and one regional trauma center for evaluation of suspected SIs from 2006 to 2017. Outcomes were any SI and any spinal cord injury (SCI). Multivariable logistic regression was performed for association of environmental and clinical factors with outcomes., Results: We analyzed 278 records, 102 patients (37%) were diagnosed with any SI and 41 (15%) were diagnosed with SCIs. Compared with patients without SI, patients with SI were more likely to be older (48 vs. 39 years), male (90% vs. 70%), with pre-existing spinal condition (62% vs. 33%), and injury caused by diving (11% vs. 2%). Multivariable logistic regression showed age (odd ratio [OR] 1.07; 95% confidence interval [CI] 1.04-1.11), diving (OR 3.5; 95% CI 3-100+), and wave height (OR 4.5; 95% CI 1.35-15.2) were associated with any SI, and a chief complaint of extremity numbness or tingling (OR 5.73; 95% CI 1.2-27.9) was associated with SCI., Conclusions: We identified older age, diving, and higher wave height as risk factors for any SI and symptoms of numbness and tingling were associated with SCIs. Clinicians should consider expediting these patients' transfers to a trauma center with neurosurgical capability., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: To determine the effects of adjunctive therapeutic hypothermia, by comparing hyperbaric oxygen therapy versus hyperbaric oxygen therapy combined with therapeutic hypothermia in acute severe carbon monoxide poisoning., Design: Retrospective analysis of data from our prospectively collected carbon monoxide poisoning registry., Setting: A single academic medical center in Wonju, Republic of Korea., Patients: Patients with acute severe carbon monoxide poisoning older than 18 years. Acute severe carbon monoxide poisoning was defined as mental status showing response to painful stimulus or unresponsive at the emergency department, and a continuation of this depressed mental status even after the first hyperbaric oxygen therapy. Patients were classified into the no-therapeutic hypothermia and therapeutic hypothermia groups. Hyperbaric oxygen therapy was performed up to twice within 24 hours after emergency department arrival, whereas therapeutic hypothermia was performed at a body temperature goal of 33°C for 24 hours using an endovascular cooling device after the first hyperbaric oxygen therapy., Interventions: Hyperbaric oxygen therapy versus hyperbaric oxygen therapy combined with therapeutic hypothermia., Measurements and Main Results: We investigated the difference in the Global Deterioration Scale score at 1 and 6 months after carbon monoxide exposure, between the no-therapeutic hypothermia and therapeutic hypothermia groups. Global Deterioration Scale scores were classified as follows: 1-3 points (favorable neurocognitive outcome) and 4-7 points (poor neurocognitive outcome). During the study period, 37 patients were treated for acute severe carbon monoxide poisoning, with 16 and 21 patients in the no-therapeutic hypothermia and therapeutic hypothermia groups, respectively. The therapeutic hypothermia group demonstrated significantly higher number of patients with favorable outcomes (p = 0.008) at 6 months after carbon monoxide exposure and better improvement of the 6-month Global Deterioration Scale score than the 1-month score (p = 0.006)., Conclusions: Our data suggest that in acute severe carbon monoxide poisoning, patients who were treated using therapeutic hypothermia combined with hyperbaric oxygen therapy had significantly more favorable neurocognitive outcomes at 6 months after carbon monoxide exposure than those treated with hyperbaric oxygen therapy alone.

We hypothesized that elevations of microparticles (MPs) would occur with morphine administration to mice. Repetitive dosing to induce anti-nociceptive tolerance increases blood-borne MPs by 8-fold, and by 10-fold in deep cervical lymph nodes draining brain glymphatics. MPs express proteins specific to cells including neutrophils, microglia, astrocytes, neurons and oligodendrocytes. Interleukin (IL)-1β content of MPs increases 68-fold. IL-1β antagonist administration diminishes blood-borne and cervical lymph node MPs, and abrogates tolerance induction. Intravenous polyethylene glycol Telomer B, a surfactant that lyses MPs, and intraperitoneal methylnaltrexone also inhibit MPs elevations and tolerance. Critically, neutropenic mice do not develop anti-nociceptive tolerance, elevations of blood-borne or cervical node MPs. Immunohistochemical evidence for microglial activation by morphine does not correlated with the MPs response pattern. Neutrophil-derived MPs appear to be required for morphine-induced anti-nociceptive tolerance. Further, patients entering treatment for opioid use disorder exhibit similar MPs elevations as do tolerant mice., Competing Interests: Competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: Patients with spontaneous intracranial hemorrhage (sICH) have poor outcomes, in part because of blood pressure variability (BPV). Patients with sICH causing elevated intracranial pressure (ICP) are frequently transferred to tertiary centers for neurosurgical interventions. We hypothesized that BPV and care intensity during transport would correlate with outcomes in patients with sICH and elevated ICP., Methods: We analyzed charts from adult sICH patients who were transferred from emergency departments to a quaternary academic center from January 1, 2011, to September 30, 2015, and received external ventricular drainage. Outcomes were in-hospital mortality and the Glasgow Coma Scale on day 5 (HD5GCS). Multivariable and ordinal logistic regressions were used for associations between clinical factors and outcomes., Results: We analyzed 154 patients, 103 (67%) had subarachnoid hemorrhage and 51 (33%) intraparenchymal hemorrhage; 38 (25%) died. BPV components were similar between survivors and nonsurvivors and not associated with mortality. Each additional intervention during transport was associated with a 5-fold increase in likelihood to achieve a higher HD5GCS (odds ratio = 5.4; 95% confidence interval, 1.7-16; P = .004)., Conclusion: BPV during transport was not associated with mortality. However, high standard deviation in systolic blood pressure during transport was associated with lower HD5GCS in patients with intraparenchymal hemorrhage. Further studies are needed to confirm our observations., (Copyright © 2019 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.)

Objective: Mechanical thrombectomy is the treatment of choice for acute ischemic strokes from large vessel occlusions. Absolute blood pressure and blood pressure variability (BPV) may affect patients' outcome. We hypothesized that patients' outcomes were not associated with BPV during transport between hospitals in the era of effective thrombectomy., Methods: We performed a retrospective observational review of adult patients admitted to our comprehensive stroke center who underwent mechanical thrombectomy between January 1, 2015, and December 31, 2018. Data were collected from our stroke registry and transportation records. Outcomes were defined as 90-day modified Rankin Scale (mRS) ≤2 and any acute kidney injury (AKI) during hospitalization., Results: We analyzed 134 eligible patients. The mean age was 66 years (standard deviation = 14 years). Forty percent achieved mRS ≤2, and 16% had an AKI. BPV and maximum systolic blood pressures during transport were examined as variables to determine outcome. We found BPV was similar between patients with good and bad functional independence. Furthermore, the maximum systolic blood pressure during transport (odds ratio = 0.98; 95% confidence interval, 0.96-0.99; P = .038), not BPV, was associated with a lower likelihood of mRS ≤2. No similar correlation of analyzed blood pressure variables could be found for AKI as an outcome., Conclusion: The maximum systolic blood pressure was associated with worse functional outcomes in stroke patients transported for thrombectomy. Prehospital clinicians should be cognizant of high blood pressure among patients with acute ischemic stroke from large vessel occlusion during transport and treat accordingly., (Copyright © 2020 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.)

The pathogenesis of predominantly neurological decompression sickness (DCS) is multifactorial. In SCUBA diving, besides gas bubbles, DCS has been linked to microparticle release, impaired endothelial function, and platelet activation. This study focused on vascular damage and its potential role in the genesis of DCS in breath-hold diving. Eleven breath-hold divers participated in a field study comprising eight deep breath-hold dives with short surface periods and repetitive breath-hold dives lasting for 6 h. Endothelium-dependent vasodilation of the brachial artery, via flow-mediated dilation (FMD), and the number of microparticles (MPs) were assessed before and after each protocol. All measures were analyzed by two-way within-subject ANOVA (2 × 2 ANOVA; factors: time and protocol). Absolute FMD was reduced following both diving protocols ( p < 0.001), with no interaction ( p = 0.288) or main effect of protocol ( p = 0.151). There was a significant difference in the total number of circulating MPs between protocols ( p = 0.007), where both increased post-dive ( p = 0.012). The number of CD31+/CD41- and CD66b+ MP subtypes, although different between protocols ( p < 0.001), also increased by 41.0% ± 56.6% ( p = 0.050) and 60.0% ± 53.2% ( p = 0.045) following deep and repetitive breath-hold dives, respectively. Both deep and repetitive breath-hold diving lead to endothelial dysfunction that may play an important role in the genesis of neurological DCS.

Production of blood-borne microparticles (MPs), 0.1-1 µm diameter vesicles, and interleukin (IL)-1β in response to high pressure is reported in lab animals and associated with pathological changes. It is unknown whether the responses occur in humans, and whether they are due to exposure to high pressure or to the process of decompression. Blood from research subjects exposed in hyperbaric chambers to air pressure equal to 18 meters of sea water (msw) for 60 minutes or 30 msw for 35 minutes were obtained prior to and during compression and 2 hours post-decompression. MPs and intra-particle IL-1β elevations occurred while at pressure in both groups. At 18 msw (n = 15) MPs increased by 1.8-fold, and IL-1β by 7.0-fold (p < 0.05, repeated measures ANOVA on ranks). At 30 msw (n = 16) MPs increased by 2.5-fold, and IL-1β by 4.6-fold (p < 0.05), and elevations persisted after decompression with MPs elevated by 2.0-fold, and IL-1β by 6.0-fold (p < 0.05). Whereas neutrophils incubated in ambient air pressure for up to 3 hours ex vivo did not generate MPs, those exposed to air pressure at 180 kPa for 1 hour generated 1.4 ± 0.1 MPs/cell (n = 8, p < 0.05 versus ambient air), and 1.7 ± 0.1 MPs/cell (p < 0.05 versus ambient air) when exposed to 300 kPa for 35 minutes. At both pressures IL-1β concentration tripled (p < 0.05 versus ambient air) during pressure exposure and increased 6-fold (p < 0.05 versus ambient air) over 2 hours post-decompression. Platelets also generated MPs but at a rate about 1/100 that seen with neutrophils. We conclude that production of MPs containing elevated concentrations of IL-1β occur in humans during exposure to high gas pressures, more so than as a response to decompression. While these events may pose adverse health threats, their contribution to decompression sickness development requires further study.

Fluorescence-mediated photoplethysmography (FM-PPG) is the first routine clinical methodology by which to quantifiably measure tissue blood perfusion in absolute terms (mL blood/sec ∗ mm 2 tissue). The FM-PPG methodology has been described in detail previously in this journal (MVR 114, 2017, 92-100), along with initial proof-of-concept measurements of blood perfusion in both ocular and forearm skin tissues. The motivation for the current study was to investigate whether FM-PPG can be used readily and routinely under realistic clinical conditions. The vehicle for doing this was to measure medial foot capillary blood flow, i.e., tissue perfusion, in 7 normal subjects, mean = 6.76 ± 2.29 E-005 mL/(sec ∙ mm 2 ), and lesion-free areas of 8 type-2 diabetic patients with skin ulceration, mean = 4.67 + 3.15 E-005 mL/(sec ∙ mm 2 ). Thus, perfusion in the diabetics was found to be moderately lower than that in the normal control subjects. Earlier skin perfusion measurements in medial forearms of 4 normal subjects, mean = 2.64 + 0.22 E-005 mL/(sec ∙ mm 2 ), were lower than both the normal and diabetic foot perfusion measurements. Variability in the heartbeat-to-heartbeat blood perfusion pulses in the skin capillaries, defined as the ratio of the standard deviation among beat-to-beat pulses divided by the mean perfusion of those pulses, was determined for each subject. Average variability in foot skin was 21% in the diabetic population, versus 16% for normal subjects; and it was 18% in forearm skin. We conclude that absolute quantitative FM-PPG measurement of skin blood perfusion at the level of nutritive capillaries is feasible routinely under clinical conditions, allowing for quantitative measurement of skin tissue blood perfusion in absolute terms., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Hyperbaric oxygen (HBO 2 ) became a mainstay for treating decompression sickness (DCS) because bubbles are associated with the disorder. Inflammatory processes including production of circulating microparticles (MPs) have now been shown to occur with DCS, leading to questions regarding pathophysiology and the role for HBO 2 . We investigated effects of HBO 2 on mice exposed to 790 kPa air pressure for 2 h, which triggers elevations of MPs ladened with interleukin (IL)-1β that cause diffuse vascular injuries. Exposure to 283 kPa O 2 (HBO 2 ) inhibited MP elevations at 2 h postdecompression by 50% when applied either prophylactically or as treatment after decompression, and the MP number remained suppressed for 13 h in the prophylactic group. Particle content of IL-1β at 2 h postdecompression was 139.3 ± 16.2 [means ± SE; n = 11, P < 0.05) pg/million MPs vs. 8.2 ± 1.0 ( n = 15) in control mice, whereas it was 31.5 ± 6.1 ( n = 6, not significant vs. control (NS)] in mice exposed to HBO 2 prophylactically, and 16.6 ± 6.3 ( n = 7, NS) when HBO 2 was administered postdecompression. IL-1β content in MPs was similar in HBO 2 -exposed mice at 13 h postdecompression. HBO 2 also inhibited decompression-associated neutrophil activation and diffuse vascular leak. Immunoprecipitation studies demonstrated that HBO 2 inhibits high-pressure-mediated neutrophil nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 inflammasome oligomerization. Furthermore, MPs isolated from decompressed mice cause vascular injuries when injected into naïve mice, but if decompressed mice were exposed to HBO 2 before MP harvest, vascular injuries were inhibited. We conclude that HBO 2 impedes high-pressure/decompression-mediated inflammatory events by inhibiting inflammasome formation and IL-1β production. NEW & NOTEWORTHY High pressure/decompression causes vascular damage because it stimulates production of microparticles that contain high concentrations of interleukin-1β, and hyperbaric oxygen can prevent injuries.

We examined if the diving-induced vascular changes in the peripheral and cerebral circulation could be prevented by oral antioxidant supplementation. Fourteen divers performed a single scuba dive to eighteen meter sea water for 47 min. Twelve of the divers participated in a follow-up study involving breathing 60% of oxygen at ambient pressure for 47 min. Before both studies, participants ingested vitamin C (2 g/day) or a placebo capsule for 6 days. After a 2-wk washout, the study was repeated with the different condition. Endothelium-dependent vasodilator function of the brachial artery was assessed pre- and postintervention using the flow-mediated dilation (FMD) technique. Transcranial Doppler ultrasound was used to measure intracranial blood velocities pre- and 90 min postintervention. FMD was reduced by ∼32.8% and ∼21.2% postdive in the placebo and vitamin C trial and posthyperoxic condition in the placebo trial by ∼28.2% ( P < 0.05). This reduction in FMD was attenuated by ∼10% following vitamin C supplementation in the hyperoxic study ( P > 0.05). Elevations in intracranial blood velocities 30 min after surfacing from diving were reduced in the vitamin C study compared with the placebo trial ( P < 0.05). O 2 breathing had no postintervention effects on intracranial velocities ( P > 0.05). Prophylactic ingestion of vitamin C effectively abrogated peripheral vascular dysfunction following exposure to 60% O 2 but did not abolish the postdive decrease in FMD. Transient elevations of intracranial velocities postdive were reduced by vitamin C. These findings highlight the differential influence of vitamin C on peripheral and cerebral circulations following scuba diving, which are only partly mediated via hyperoxia.

Inflammatory mediators are known to be elevated in association with decompression from elevated ambient pressure, but their role in tissue damage or overt decompression sickness is unclear. Circulating microparticles (MPs) are also known to increase, and because interleukin (IL)-1β is packaged within these particles, we hypothesized that IL-1β was responsible for tissue injuries. Here, we demonstrate that elevations of circulating MPs containing up to ninefold higher concentrations of IL-1β occur while mice are exposed to high air pressure (790 kPa), whereas smaller particles carrying proteins specific to exosomes are not elevated. MPs number and intra-particle IL-1β concentration increase further over 13 h post decompression. MPs also exhibit intra-particle elevations of tumor necrosis factor-α, caspase-1, inhibitor of κB kinase-β, and inhibitor of κB kinase-γ, and elevated IL-6 is adsorbed to the surface of MPs. Contrary to lymphocytes, neutrophil nucleotide-binding oligomerization domain-like receptor, pyrin domain containing 3 (NLRP3) inflammasome oligomerization and cell activation parameters occur during high pressure exposure, and additional evidence for activation is manifested post decompression. Diffuse vascular damage, although not apparent immediately post decompression, was present 2 h later and remained elevated for at least 13 h. Prophylactic administration of an IL-1β receptor inhibitor or neutralizing antibody to IL-1β inhibited MPs elevations, increases of all MPs-associated pro-inflammatory agents, and vascular damage. We conclude that an auto-activation process triggered by high pressure stimulates MPs production and concurrent inflammasome activation, and IL-1β is a proximal factor responsible for further cytokine production and decompression-associated vascular injuries. NEW & NOTEWORTHY Elevations in circulating microparticles due to decompression have been documented in humans and animals. This report shows that intra-particle interleukin-1β causes vascular damage that can be abrogated by interventions directed against this cytokine.

The aims of this study were: (1) to test whether oscillatory shear stress further exacerbates endothelial dysfunction in patients with moderate-severe COPD, and (2) to test whether low flow oxygen administration improves endothelial function and is protective against oscillatory shear stress-induced endothelial dysfunction in patients with moderate-severe COPD. In 17 patients and 10 age-matched non-smoking control subjects we examined brachial artery flow-mediated dilation (FMD) and circulating microparticles before and after 20 minutes of experimentally-induced oscillatory shear stress. COPD patients performed this intervention a second time following a 20-minute wash in period of low flow supplemental oxygen to normalize arterial oxygen saturation. COPD patients had ~six-fold greater baseline retrograde shear rate (P < 0.05) and lower FMD (P < 0.05). The oscillatory shear stress intervention induced significant decreases in brachial artery FMD of all groups (P < 0.05). Oscillatory shear stress elevated circulating markers of endothelial cell apoptosis (CD31+/CD41b- microparticles) in COPD patients, but not age-matched controls. Supplemental oxygen administration abrogated the oscillatory shear stress-induced increase in CD31+/CD41b- microparticles, and improved FMD after accounting for the shear stress stimulus. We have demonstrated that acutely disturbed blood flow with increased retrograde shear stress further deteriorates the already impaired endothelial function with attendant endothelial apoptosis in patients with moderate-severe COPD.

Microparticles are lipid bilayer-enclosed vesicles produced by cells under oxidative stress. MP production is elevated in patients with diabetes, but the underlying cellular mechanisms are poorly understood. We hypothesized that raising glucose above the physiological level of 5.5 mm would stimulate leukocytes to produce MPs and activate the nucleotide-binding domain, leucine-rich repeat pyrin domain-containing 3 (NLRP3) inflammasome. We found that when incubated in buffer with up to 20 mm glucose, human and murine neutrophils, but not monocytes, generate progressively more MPs with high interleukin (IL)-1β content. Enhanced MP production required generation of reactive chemical species by mitochondria, NADPH oxidase, and type 2 nitric-oxide synthase (NOS-2) and resulted in S -nitrosylation of actin. Depleting cells of capon (C-terminal PDZ ligand of neuronal nitric-oxide synthase protein), apoptosis-associated speck-like protein containing C-terminal caspase recruitment domain (ASC), or pro-IL-1β prevented the hyperglycemia-induced enhancement of reactive species production, MP generation, and IL-1β synthesis. Additional components required for these responses included inositol 1,3,5-triphosphate receptors, PKC, and enhancement of filamentous-actin turnover. Numerous proteins become localized to short filamentous actin in response to S -nitrosylation, including vasodilator-stimulated phosphoprotein, focal adhesion kinase, the membrane phospholipid translocation enzymes flippase and floppase, capon, NLRP3, and ASC. We conclude that an interdependent oxidative stress response to hyperglycemia perturbs neutrophil cytoskeletal stability leading to MP production and IL-1β synthesis., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

The purpose of this study was to explore perceptions among people with type 2 diabetes about foot ulcers and lower extremity amputations. This was a qualitative observational study utilizing open-ended, semistructured interviews of 39 people with diabetes who were purposively selected because they had either a foot ulcer (n = 19) or a lower extremity amputation (n = 20). Interviews were audio-recorded, deidentified, and entered into NVivo 10.0 for coding and analysis. Our integrated analytic approach combined inductively and deductively derived codes that were applied to all transcripts. Coded data were summarized and examined for patterns. Participants' description of the relationship between diabetes and their foot ulcer or amputation revealed a limited understanding of the disease process. Disruption and loss of independence was expressed whether the person had a foot ulcer or an amputation. Treatment recommendations for foot ulcers were viewed by most as extremely difficult. Amputation was a feared outcome, but some learned to adapt and, at times felt that the amputation enhanced their quality of life. Clinicians have assumed that a focus on limb salvage is preferred over a major amputation. However, because of the complexity of care requiring frequent healthcare provider visits, the frequency of care failure, the frequency of recurrence, and mortality associated with having had a foot ulcer, it may be more appropriate for clinicians to prioritize quality-of-life salvage. Foot ulcer treatment failure may be due to a lack of providers' understanding of the impact of treatment on a patient's life., (© 2017 by the Wound Healing Society.)

Health risks are described from elevated indoor air carbon dioxide (CO 2 ), which often ranges from 1,000 to 4,000 ppm, but the mechanisms are unknown. Here, we demonstrate that mice exposed for 2 h to 2,000 or 4,000 ppm CO 2 exhibit, respectively, 3.4 ± 0.9-fold (SE, n = 6) and 4.1 ± 0.7-fold ( n = 10) elevations in circulating microparticles (MPs); neutrophil and platelet activation, and vascular leak in brain, muscle, and distal colon. Interleukin (IL)-1β content of MPs also increases after 2,000 ppm by 3.8 ± 0.6-fold ( n = 6) and after 4,000 ppm CO 2 by 9.3 ± 1.1-fold ( n = 10) greater than control. CO 2 -induced vascular damage is abrogated by treating mice with an antibody to IL-1β or an IL-1β receptor inhibitor. Injecting naïve mice with CO 2 -induced MPs expressing a protein found on mature neutrophils recapitulates vascular damage as seen with elevated CO 2 , and destruction of MPs in CO 2 -exposed mice abrogates vascular injuries without altering neutrophil or platelet activation. We conclude that environmentally relevant elevations of CO 2 trigger neutrophils to generate MPs containing high concentrations of IL-1β that cause diffuse inflammatory vascular injury. NEW & NOTEWORTHY Elevated levels of CO 2 are often found in indoor air and cause adverse health effects, but the mechanisms have not been identified. In a murine model, environmentally relevant levels of CO 2 were found to cause diffuse vascular damage because neutrophils are stimulated to produce microparticles that contain high concentrations of interleukin-1β., (Copyright © 2017 the American Physiological Society.)

We hypothesized that elevations of carbon dioxide (CO 2 ) commonly found in modern buildings will stimulate leukocytes to produce microparticles (MPs) and activate the nucleotide-binding domain-like receptor 3 (NLRP3) inflammasome due to mitochondrial oxidative stress. Human and murine neutrophils generate MPs with high interleukin-1β (IL-1β) content when incubated ex vivo in buffer equilibrated with 0.1-0.4% additional CO 2 . Enhanced MPs production requires mitochondrial reactive oxygen species production, which is mediated by activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase. Subsequent events leading to MPs generation include perturbation of inositol 1,3,5-triphosphate receptors, a transient elevation of intracellular calcium, activation of protein kinase C and NADPH oxidase (Nox). Concomitant activation of type-2 nitric oxide synthase yields secondary oxidants resulting in actin S-nitrosylation and enhanced filamentous actin turnover. Numerous proteins are linked to short filamentous actin including vasodilator-stimulated phosphoprotein, focal adhesion kinase, the membrane phospholipid translocation enzymes flippase and floppase, and the critical inflammasome protein ASC (Apoptosis-associated Speck protein with CARD domain). Elevations of CO 2 cause oligomerization of the inflammasome components ASC, NLRP3, caspase 1, thioredoxin interacting protein, and calreticulin - a protein from endoplasmic reticulum, leading to IL-1β synthesis. An increased production rate of MPs containing elevated amounts of IL-1β persists for hours after short-term exposures to elevated CO 2 ., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose/Aim: High pressures of gases such as nitrogen enhance production of singlet oxygen. Therefore, we hypothesized that growth of non-small cell lung cancer (NSCLC) A549 cells and a human-derived NSCLC explant could be inhibited by an oxidative stress mechanism using high-pressure nitrogen., Materials and Methods: Growth of human NSCLC explants and A549 cells in Matrigel were assessed after implantation into nude mice who were exposed to elevated pressures., Results: Subcutaneous implant growth of NSCLC in nude mice was inhibited by a daily 78-minute protocol using nitrogen/oxygen breathing mixture such that at the maximum pressure of 2.78 atmospheres over ambient, mice breathed oxygen at normal atmospheric pressure. In vivo growth inhibition of A549 cells by high-pressure nitrogen could be abrogated in subcutaneous Matrigel implants when supplemented with 10-mM N-acetylcysteine as an antioxidant. Ex vivo A549 cell exposures exhibited elevated singlet oxygen production, and reactive oxygen species were produced for up to 4 hours after short-term high-pressure nitrogen exposure., Conclusions: This pilot study demonstrates that elevated normoxic nitrogen pressure can exacerbate oxidative stress in NSCLC to inhibit growth.

Background: Local and systemic inflammatory responses are initiated early after traumatic brain injury (TBI), and may play a key role in the secondary injury processes resulting in neuronal loss and neurological deficits. However, the mechanisms responsible for the rapid expansion of neuroinflammation and its long-term progression have yet to be elucidated. Here, we investigate the role of microparticles (MP), a member of the extracellular vesicle family, in the exchange of pro-inflammatory molecules between brain immune cells, as well as their transfer to the systemic circulation, as key pathways of inflammation propagation following brain trauma., Methods: Adult male C57BL/6 mice were subjected to controlled cortical impact TBI for 24 h, and enriched MP were isolated in the blood, while neuroinflammation was assessed in the TBI cortex. MP were characterized by flow cytometry, and MP content was assayed using gene and protein markers for pro-inflammatory mediators. Enriched MP co-cultured with BV2 or primary microglial cells were used for immune propagation assays. Enriched MP from BV2 microglia or CD11b-positive microglia from the TBI brain were stereotactically injected into the cortex of uninjured mice to evaluate MP-related seeding of neuroinflammation in vivo., Results: As the neuroinflammatory response is developing in the brain after TBI, microglial-derived MP are released into the circulation. Circulating enriched MP from the TBI animals can activate microglia in vitro. Lipopolysaccharide stimulation increases MP release from microglia in vitro and enhances their content of pro-inflammatory mediators, interleukin-1β and microRNA-155. Enriched MP from activated microglia in vitro or CD11b-isolated microglia/macrophage from the TBI brain ex vivo are sufficient to initiate neuroinflammation following their injection into the cortex of naïve (uninjured) animals., Conclusions: These data provide further insights into the mechanisms underlying the development and dissemination of neuroinflammation after TBI. MP loaded with pro-inflammatory molecules initially released by microglia following trauma can activate additional microglia that may contribute to progressive neuroinflammatory response in the injured brain, as well as stimulate systemic immune responses. Due to their ability to independently initiate inflammatory responses, MP derived from activated microglia may provide a potential therapeutic target for other neurological disorders in which neuroinflammation may be a contributing factor.

Background and Aims: Exposing the endothelium to acute periods of imposed oscillatory shear stress reduces endothelial function and elevates circulating microparticles (MPs). Oscillatory shear stress may be especially pathogenic when superimposed on hypoxia, an environmental stimulus that disrupts the endothelial milieu. We examined the effects of acute manipulation of oscillatory shear stress on endothelial function and circulating MPs at sea level (SL) and high altitude (HA)., Methods: Healthy adults (n = 12) participated, once at SL and once on the second or third day at HA (3800 m). Oscillatory shear stress was provoked using a 30-min distal cuff occlusion intervention (75 mmHg). Endothelial function was assessed before and immediately after the intervention in the brachial artery by reactive hyperaemia flow-mediated dilatation (FMD). Venous blood samples of MPs (flow cytometry) were obtained before and during the last five minutes of the shear intervention., Results: At baseline, circulating MPs were two-fold higher at HA (p = 0.011) and brachial artery diameter was constricted (p = 0.015). Although the intervention at SL increased endothelial-derived MPs by 83 ± 39% (mean ± SEM; p = 0.021), FMD was unaltered. Conversely, at HA, the intervention elicited a 26 ± 11% reduction in FMD (p = 0.020); this reduction was inversely correlated with the change in total circulating MPs (r = -0.737, p = 0.006) and the change in endothelial-derived MPs (r = -0.614, p = 0.034)., Conclusions: The vascular endothelium appears to be susceptible to periods of oscillatory shear stress at HA, where impairments in endothelium-dependent vasodilatation may be amplified by endothelial injury. These findings have important implications for understanding the early impact of clinical situations of hypoxaemia on the vascular endothelium., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

This investigation explored the mechanism for microparticles (MPs) production by human and murine platelets exposed to high pressures of inert gases. Results demonstrate that MPs production occurs via an oxidative stress response in a dose-dependent manner and follows the potency series N 2 >Ar>He. Gases with higher van der Waals volumes or polarizability such as SF 6 and N 2 O, or hydrostatic pressure, do not cause MPs production. Singlet O 2 is generated by N 2 , Ar and He, which is linked to NADPH oxidase (NOX) activity. Progression of oxidative stress involves activation of nitric oxide synthase (NOS) leading to S-nitrosylation of cytosolic actin. Exposure to gases enhances actin filament turnover and associations between short actin filaments, NOS, vasodilator-stimulated phosphoprotein (VASP), focal adhesion kinase (FAK) and Rac1. Inhibition of NOS or NOX by chemical inhibitors or using platelets from mice lacking NOS2 or the gp91phox component of NOX diminish generation of reactive species, enhanced actin polymerization and MP generation by high pressure gases. We conclude that by initiating a sequence of progressive oxidative stress responses high pressure gases cause platelets to generate MPs., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Aim: SCUBA diving frequently involves repetitive exposures. The goal of this study was to see how exercise impacts microparticles (MPs), endothelial function and venous gas emboli (VGE) throughout multiple dives., Methods: Sixteen divers in two groups (G1 and G2) each completed six dives, three preceded by exercise (EX) and three as controls (CON). Blood for MP analysis was collected before and after each dive. VGE were monitored via transthoracic echocardiography 30, 60 and 90 min after surfacing. Exercise before diving consisted of 60-min running including eight, 3-min intervals at 90% VO2max., Results: Exercise did not have a significant impact on VGE. There was no significant difference in MP counts between EX and CON. Both groups experienced a significant decrease in MP counts in the last three dives compared to the first three (G1 P = 0·0008, G2 P = 0001). Other indices of neutrophil/platelet interaction (dual-positive CD63/41 and CD62/41) show a significant increase (P = 0·004 and 0·0001) in G2., Conclusion: Both groups experienced a significant decrease in MPs at all measurements in the second series of dives compared to the first, regardless of the placement of exercise. Whether this is related to an effect of suppression of MPs or exercise timing is not clear., (© 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.)

Recent studies of stranded marine mammals indicate that exposure to underwater military sonar may induce pathophysiological responses consistent with decompression sickness (DCS). However, DCS has been difficult to diagnose in marine mammals. We investigated whether blood microparticles (MPs, measured as number/μl plasma), which increase in response to decompression stress in terrestrial mammals, are a suitable biomarker for DCS in marine mammals. We obtained blood samples from trained Steller sea lions (Eumetopias jubatus, 4 adult females) wearing time-depth recorders that dove to predetermined depths (either 5 or 50 meters). We hypothesized that MPs would be positively related to decompression stress (depth and duration underwater). We also tested the effect of feeding and exercise in isolation on MPs using the same blood sampling protocol. We found that feeding and exercise had no effect on blood MP levels, but that diving caused MPs to increase. However, blood MP levels did not correlate with diving depth, relative time underwater, and presumed decompression stress, possibly indicating acclimation following repeated exposure to depth., (Copyright © 2016 the American Physiological Society.)

Management of neuropathic foot ulcers in patients with diabetes (DFUs) has changed little over the past decade, and there is currently no objective method to gauge probability of successful healing. We hypothesized that studies of stem/progenitor cells (SPCs) in the early weeks of standard wound management could predict who will heal within 16 weeks. Blood and debrided wound margins were collected for 8 weeks from 100 patients undergoing weekly evaluations and treatment. SPC number and intracellular content of hypoxia-inducible factors (HIFs) were evaluated by flow cytometry and immunohistochemistry. More SPCs entered the bloodstream in the first 2 weeks of care in patients who healed (n = 37) than in those who did not (n = 63). Logistic regression demonstrated that the number of blood-borne SPCs and the cellular content of HIFs at study entry and the first-week follow-up visit predicted healing. Strong correlations were found among week-to-week assessments of blood-borne SPC HIF factors. We conclude that assays of SPCs during the first weeks of care in patients with DFUs can provide insight into how well wounds will respond and may aid with decisions on the use of adjunctive measures., (© 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)

Endothelin-1 (ET-1), tissue plasminogen activator (tPA), and extracellular signal-regulated kinases-mitogen activated protein kinase (ERK-MAPK) are mediators of impaired cerebral hemodynamics after fluid percussion brain injury (FPI) in piglets. Microparticles (MPs) are released into the circulation from a variety of cells during stress, are pro-thrombotic and pro-inflammatory, and may be lysed with polyethylene glycol telomere B (PEG-TB). We hypothesized that MPs released after traumatic brain injury impair hypotensive cerebrovasodilation and that PEG-TB protects the vascular response via MP lysis, and we investigated the relationship between MPs, tPA, ET-1, and ERK-MAPK in that process. FPI was induced in piglets equipped with a closed cranial window. Animals received PEG-TB or saline (vehicle) 30-minutes post-injury. Serum and cerebrospinal fluid (CSF) were sampled and pial arteries were measured pre- and post-injury. MPs were quantified by flow cytometry. CSF samples were analyzed with enzyme-linked immunosorbent assay. MP levels, vasodilatory responses, and CSF signaling assays were similar in all animals prior to injury and treatment. After injury, MP levels were elevated in the serum of vehicle but not in PEG-TB-treated animals. Pial artery dilation in response to hypotension was impaired after injury but protected in PEG-TB-treated animals. After injury, CSF levels of tPA, ET-1, and ERK-MAPK were all elevated, but not in PEG-TB-treated animals. PEG-TB-treated animals also showed reduction in neuronal injury in CA1 and CA3 hippocampus, compared with control animals. These results show that serum MP levels are elevated after FPI and lead to impaired hypotensive cerebrovasodilation via over-expression of tPA, ET-1, and ERK-MAPK. Treatment with PEG-TB after injury reduces MP levels and protects hypotensive cerebrovasodilation and limits hippocampal neuronal cell injury.

Risk in SCUBA diving is often associated with the presence of gas bubbles in the venous circulation formed during decompression. Although it has been demonstrated time-after-time that, while venous gas emboli (VGE) often accompany decompression sickness (DCS), they are also frequently observed in high quantities in asymptomatic divers following even mild recreational dive profiles. Despite this VGE are commonly utilized as a quantifiable marker of the potential for an individual to develop DCS. Certain interventions such as exercise, antioxidant supplements, vibration, and hydration appear to impact VGE production and the decompression process. However promising these procedures may seem, the data are not yet conclusive enough to warrant changes in decompression procedure, possibly suggesting a component of individual response. We hypothesize that the impact of exercise varies widely in individuals and once tested, recommendations can be made that will reduce individual decompression stress and possibly the incidence of DCS. The understanding of physiological adaptations to diving stress can be applied in different diseases that include endothelial dysfunction and microparticle (MP) production. Exercise before diving is viewed by some as a protective form of preconditioning because some studies have shown that it reduces VGE quantity. We propose that MP production and clearance might be a part of this mechanism. Exercise after diving appears to impact the risk of adverse events as well. Research suggests that the arterialization of VGE presents a greater risk for DCS than when emboli are eliminated by the pulmonary circuit before they have a chance to crossover. Laboratory studies have demonstrated that exercise increases the incidence of crossover likely through extra-cardiac mechanisms such as intrapulmonary arterial-venous anastomoses (IPAVAs). This effect of exercise has been repeated in the field with divers demonstrating a direct relationship between exercise and increased incidence of arterialization., (Copyright © 2015 Elsevier Ltd. All rights reserved.)