Explore the vast range of titles available.

Background Oxygen-rich breathing mixtures up to 100% are used in some underwater diving operations for several reasons. Breathing elevated oxygen partial pressures (PO 2 ) increases the risk of developing central nervous system oxygen toxicity (CNS-OT) which could impair performance or result in a seizure and subsequent drowning. We aimed to study the dynamics of the electrodermal activity (EDA) and heart rate (HR) while breathing elevated PO 2 in the hyperbaric environment (HBO 2 ) as a possible means to predict impending CNS-OT. Methods EDA is recorded during 50 subject exposures (26 subjects) to evaluate CNS-OT in immersed (head out of water) exercising divers in a hyperbaric chamber breathing 100% O 2 at 35 feet of seawater (FSW), (PO 2  = 2.06 ATA) for up to 120 min. Results 32 subject exposures exhibit symptoms “definitely” or “probably” due to CNS-OT before the end of the exposure, whereas 18 do not. We obtain traditional and time-varying spectral indices (TVSymp) of EDA to determine its utility as predictive physio markers. Variations in EDA and heart rate (HR) for the last 5 min of the experiment are compared to baseline values prior to breathing O 2 . In the subset of experiments where “definite” CNS-OT symptoms developed, we find a significant elevation in the mean ± standard deviation TVSymp value 57 ± 79 s and median of 10 s, prior to symptoms. Conclusions In this retrospective analysis, TVSymp may have predictive value for CNS-OT with high sensitivity (1.0) but lower specificity (0.48). Additional work is being undertaken to improve the detection algorithm. Plain Language Summary This study looked at the effects of breathing high levels of oxygen during underwater diving and the risk of central nervous system oxygen toxicity. This toxicity can cause problems with movement, seizures or even drowning. We wanted to see if changes in skin and heart activity could help predict the symptoms of toxicity. We tested 26 divers (50 dives) in a special chamber. They breathed pure oxygen at increased pressure (equivalent to being underwater at 35 feet). 32 dives showed signs of toxicity, while 18 did not. We looked at the electrodermal activity (a measurement of the skin conductance) and heart rate data to see if they could warn of an issue. We found that in dives where toxicity symptoms definitely developed, there were significant changes in electrodermal activity around 57 s before symptoms appeared. While this method was very sensitive, it wasn’t always specific. We are working on improving this prediction method. This may be used to warn divers of dangerous gases so they can switch breathing gases or move to a shallower depth, and can improve the chances of escaping a disabled submarine. Posada-Quintero et al. study the dynamics of the electrodermal activity and heart rate while breathing at elevated oxygen partial pressures in a hyperbaric environment. Electrodermal activitycan be used to predict the onset of central nervous system oxygen toxicity symptoms in divers resulting from prolonged exposure to a hyperbaric environment.

Divers who wish to prolong their time underwater while carrying less equipment often use devices called rebreathers, which recycle the gas expired after each breath instead of discarding it as bubbles. However, rebreathers’ need to replace oxygen used by breathing creates a failure mechanism that can and frequently does lead to hypoxia, loss of consciousness, and death. The purpose of this study was to determine whether a pulse oximeter could provide a useful amount of warning time to a diver with a rebreather after failure of the oxygen addition mechanism. Twenty-eight volunteer human subjects breathed on a mixed-gas rebreather in which the oxygen addition system had been disabled. The subjects were immersed in water in four separate environmental scenarios, including cold and warm water, and monitored using pulse oximeters placed at multiple locations. Pulse oximeters placed on the forehead and clipped on the nasal ala provided a mean of 32 s (±10 s SD) of warning time to divers with falling oxygen levels, prior to risk of loss of consciousness. These devices, if configured for underwater use, could provide a practical and inexpensive alarm system to warn of impending loss of consciousness in a manner that is redundant to the rebreather.

To evaluate the performance of the emOx emergency powdered oxygen portable nonpressurized delivery system. This device produces oxygen through chemical reaction and is marketed for emergency first aid use until professional medical assistance is available. Seven unmanned trials were conducted under standard laboratory conditions. Measures included oxygen flow, reaction canister external wall temperature, delivered gas temperature, and delivered gas relative humidity. The mean oxygen flow was 1.75 ± 1.58 L · min −1 (mean ± SD) with a total yield of 40.4 ± 2.6 L. Oxygen flow increased slowly and with substantial variability between reactant groups, exceeding 2.0 L · min −1 after 15.7 ± 6.4 minutes of operation. Oxygen flow briefly peaked at 5.93 ± 0.56 L · min −1 at 17.8 ± 7.9 minutes before rapidly falling to zero. The mean oxygen fraction was 0.81 ± 0.28, exceeding 0.96 in 10.7 ± 2.9 minutes. The reaction canister external wall temperature reached 54.7 ± 7.4°C. Delivered gas temperature varied little from ambient. Delivered gas relative humidity surpassed 75% in 8 ± 3 minutes and 90% in 15 ± 5 minutes of operation. A readily available, high concentration oxygen supply could have utility to manage many conditions in advance of the arrival of professional emergency medical services (EMS). Unfortunately, the highly variable activation time and low average oxygen flow rate make the rapid deployment value of the emOx equivocal. The limited total oxygen yield makes it inappropriate for conditions demanding significant oxygen resources. Advancement in oxygen concentrator systems likely holds far more promise than powdered chemical oxygen generation for first aid and emergency medical applications.

Closed-circuit oxygen rebreathers may provide high concentrations of oxygen at extremely low flow rates appropriate for field use with limited oxygen supplies. The performance of the preproduction, second-generation remote emergency medical oxygen (REMO 2) system developed for Divers Alert Network was evaluated. The unidirectional circuit was made up of a solid, prepackaged CO 2 scrubber canister (984 ± 14 [SD] g scrubber mass), standard 22-mm-inside-diameter anesthesia circuit hoses, 5-L breathing bag, 5-cm H 2O positive end-expiratory pressure valve, and oronasal mask. Oxygen flow, inspired oxygen, expired CO 2, peak inspired and expired mask pressures, time to reach scrubber canister saturation or “breakthrough” (postscrubber CO 2 concentration reaching 3.8 mm Hg), and subject tolerance were measured under standard laboratory conditions. Six trials were completed using healthy volunteers (94.7 ± 19.6 kg). Five of the 6 completed trials did not reach breakthrough at the planned trial limit of 8 hours. Mean average oxygen flow rate was 1.00 ± 0.17 L·min −1. Mean peak inspired and expired mask pressures were −5.0 ± 1.9 and 6.5 ± 1.9 cm H 2O, respectively. Subjects generally reported good tolerance to circuit breathing. The second-generation REMO 2 was well tolerated by healthy subjects during 8-hour laboratory evaluation trials. The device provided high mean inspired oxygen fractions at low mean oxygen flow rates, relatively modest mean maximal inspired and expired pressures, and excellent scrubber canister duration. Further evaluation of field performance with a patient population is warranted.

Skin antisepsis with iodine povacrylex resulted in fewer surgical-site infections than antisepsis with chlorhexidine gluconate in patients with closed limb fractures but not in those with open fractures.

Attitudes and beliefs about menstruation can place restrictions on menstruating women and girls, limiting their ability to fully participate in community life, education and employment. This paper presents evidence on menstruation-related beliefs contributing to restrictive practices in Papua New Guinea (PNG), Solomon Islands (SI) and Fiji. Focus group discussions and interviews were undertaken with 307 adolescent girls, women and men in a rural and urban site in each country. Data were analysed using an inductive thematic approach. Participants described a range of attitudes and beliefs that restrict the behaviour of menstruating women and girls. Themes include the belief that menstrual blood is 'dirty'; that when menstruating, girls and women can bring 'bad luck' to men; secrecy and shame associated with menstruation; and beliefs about the impact of certain behaviours on menstruation and health. Restrictive practices were more frequently reported in PNG and SI than Fiji, and more common in rural compared with urban sites. Some restrictions, such as avoidance of household chores, were perceived as desirable or driven by women themselves. However participants identified other restrictions, such as not being able to attend church or hygienically wash menstrual hygiene materials, as unwanted, in some cases impacting on participation in school, work and community life. Education initiatives guided by women and girls, implemented by local stakeholders and grounded in a sound understanding of specific contexts are needed to address discriminatory attitudes and beliefs that contribute to unwanted restrictions, and to support enabling attitudes and beliefs regarding menstruation.

Preimplantation factor (PIF) is an embryo derived peptide which exerts an immune modulatory effect on human endometrium, promoting immune tolerance to the embryo whilst maintaining the immune response to invading pathogens. While bovine embryos secrete PIF, the effect on the bovine endometrium is unknown. Maternal recognition of pregnancy is driven by an embryo-maternal cross talk, however the process differs between humans and cattle. As many embryos are lost during the early part of pregnancy in cattle, a greater knowledge of factors affecting the embryo-maternal crosstalk, such as PIF, is needed to improve fertility. Therefore, for the first time, we demonstrate the effect of synthetic PIF (sPIF) on the bovine transcriptome in an ex vivo bovine endometrial tissue culture model. Explants were cultured for 30h with sPIF (100nM) or in control media. Total RNA was analysed via RNA-sequencing. As a result of sPIF treatment, 102 genes were differentially expressed compared to the control ( P adj<0.1), although none by more than 2-fold. The majority of genes (78) were downregulated. Pathway analysis revealed targeting of several immune based pathways. Genes for the TNF, NF-κB, IL-17, MAPK and TLR signalling pathways were down-regulated by sPIF. However, some immune genes were demonstrated to be upregulated following sPIF treatment, including C3 . Steroid biosynthesis was the only over-represented pathway with all genes upregulated. We demonstrate that sPIF can modulate the bovine endometrial transcriptome in an immune modulatory manner, like that in the human endometrium, however, the regulation of genes was much weaker than in previous human work.

Many bioinformatics methods have been proposed for reducing the complexity of large gene or protein networks into relevant subnetworks or modules. Yet, how such methods compare to each other in terms of their ability to identify disease-relevant modules in different types of network remains poorly understood. We launched the ‘Disease Module Identification DREAM Challenge’, an open competition to comprehensively assess module identification methods across diverse protein–protein interaction, signaling, gene co-expression, homology and cancer-gene networks. Predicted network modules were tested for association with complex traits and diseases using a unique collection of 180 genome-wide association studies. Our robust assessment of 75 module identification methods reveals top-performing algorithms, which recover complementary trait-associated modules. We find that most of these modules correspond to core disease-relevant pathways, which often comprise therapeutic targets. This community challenge establishes biologically interpretable benchmarks, tools and guidelines for molecular network analysis to study human disease biology.

Dominance hierarchies are widespread in animal societies and reduce the costs of within-group conflict over resources and reproduction. Variation in stability across a social hierarchy may result in asymmetries in the benefits obtained from hierarchy formation. However, variation in the stability and behavioural costs of dominance interactions with rank remain poorly understood. Previous theoretical models have predicted that the intensity of dominance interactions and aggression should increase with rank, but these models typically assume high reproductive skew, and so their generality remains untested. Here we show in a pack of free-living dogs with a sex–age-graded hierarchy that the central region of the hierarchy was dominated by more unstable social relationships and associated with elevated aggression. Our results reveal unavoidable costs of ascending a dominance hierarchy, run contrary to theoretical predictions for the relationship between aggression and social rank in high-skew societies, and widen our understanding of how heterogeneous benefits of hierarchy formation arise in animal societies.