Blood pressure responses are dependent on call type and related to hypertension status in firefighters.

BACKGROUND: Impaired cardiovascular health is a concern for firefighters, with over 50% of line-of-duty deaths having cardiac causes. Many firefighters have hypertension and <25% have their blood pressure (BP) controlled. The alarm response could be an unidentified cardiac risk, but interestingly, the BP response to different calls and on-the-job activity is unknown. PURPOSE: We aimed to measure the physiological stress resulting from different call types (fire, medical) and job activity (riding apparatus, pre-alert alarms) through ambulatory BP (ABP) monitoring in a population of firefighters. MATERIALS AND METHODS: During 111 12-h work shifts firefighters wore an ABP monitor. BP was measured at 30-min intervals and manual measurements were prompted when the pager went off or whenever they felt stress. RESULTS: Firefighters were hypertensive (124.3 ± 9.9/78.1 ± 6.7 mmHg), overweight (30.2 ± 4.6 kg/m2), middle-aged (40.5 ± 12.6 years) and experienced (17.3 ± 11.7 years). We calculated an average 11% increase in systolic and 10.5% increase in diastolic BP with alarm. Systolic BP (141.9 ± 13.2 mmHg) and diastolic BP (84.9 ± 11.1 mmHg) and the BP surges were higher while firefighters were responding to medical calls compared to fire calls. Between BP groups we found that medical call systolic BP (p = .001, d = 1.2), diastolic BP (p = .017, d = 0.87), and fire call systolic BP (p = .03, d = 0.51) levels were higher in the hypertensive firefighters. CONCLUSION: This is the first report of BP surge responses to alarms and to occupational activities in firefighters, and medical calls elicited the largest overall responses.PLAIN LANGUAGE SUMMARYCardiovascular disease and impaired cardiovascular health are substantially more prevalent in firefighters, with over 50% of line-of-duty deaths being cardiac related.Many firefighters are diagnosed with high blood pressure (hypertension), which is known to increase the risk of heart attacks, strokes, heart disease, and other serious health complications.Upon stress, our body enacts the 'fight or flight' response where sympathetic nervous system activity triggers an immediate increase in heart rate and blood pressure. This response can be dangerous when surges reach extreme levels due to underlying impaired cardiovascular function. It is known that alarm sounds trigger a stress response.Firefighters respond to different alarms while on the job, each indicating different call types, such as a house fire or a medical emergency. Due to the prevalence of impaired cardiovascular health in firefighters, the physical stress resulting from these alerts is cause for concern.The blood pressure surge response to different call types and job activities in healthy and hypertensive firefighters had not been measured before this study.Through the ambulatory blood pressure monitoring of 111 on-duty firefighters, this study discovered that medical calls caused the greatest blood pressure and heart rate surge.Also, firefighters with hypertension experienced a greater blood pressure surge in response to alarms than their non-hypertensive co-workers.

Informal management of health and safety risks associated with alarm response by Australian firefighters.

Fire-fighters use informal strategies to manage risks to health and safety during operations. It is not known whether such strategies are used during the high-risk alarm response period. The aim of this study was to determine if informal risk management strategies are employed by Australian firefighters during the alarm response procedure, and if these strategies differ between salaried and retained personnel. Forty-six metropolitan firefighters (all male; mean age 38 years ± 10 years; 22 salaried; 24 retained) participated in semi-structured group interviews. A general inductive data analysis approach revealed that firefighters use multiple informal risk management strategies. Some similar themes were reported by both salaried and retained personnel, for example leveraging team dynamics, communication about sleep and fatigue, stress adaptation, informal debriefs, and enhancing physical preparedness. These findings could be used by fire services to tailor risk management approaches during the alarm response period. Practitioner summary: Identifying informal risk management strategies firefighters use during alarm response will allow their development, refinement and dissemination, and may help other firefighters and emergency service workers to manage these risks. This qualitative study reveals multiple informal strategies that firefighters employ during alarm response to keep themselves and their team-mates safe.

Embryonic substances induce alarm response in adult zebrafish (Danio rerio).

Many aquatic animals rely on chemicals released by injured individuals of the same species to assess predation risk. Among these chemical cues, alarm substances released from the injured skin of ostariophysan fishes have been extensively examined. In most fish species examined, these cues appear to be released by all injured individuals (including larvae, juveniles and adults) and elicit alarm responses in conspecifics. Adult alarm cues also affect development and physiology of embryos. Nonetheless, whether embryos produce alarm cues that affect adults is not known. This study reports that extracts of zebrafish (Danio rerio) embryos at 36 h post-fertilization or later induce antipredator behaviours reminiscent of those induced by skin alarm substances. At an equivalent of 10-6 g embryo per millilitre, the extract induced bottom-dwelling and freezing in adults. These behaviours are consistent with those induced by adult alarm substances. This study concludes that zebrafish embryos produce alarm substances.

Exposure to a putative alarm cue reduces downstream drift in larval sea lamprey Petromyzon marinus in the laboratory.

An experimental mesocosm study suggested larval sea lamprey Petromyzon marinus detect and respond to an alarm cue released by dead adult conspecifics. Larvae exhibited a reduced tendency to move downstream when exposed to the cue and were less likely to move under continuous v. pulsed exposure. These findings support the hypothesis that short-term exposure to the alarm cue would probably result in retraction into the burrow, consistent with the blind, cryptic lifestyle of the larval P. marinus.

Mechanistic modeling of alarm signaling in seed-harvester ants.

Ant colonies demonstrate a finely tuned alarm response to potential threats, offering a uniquely manageable empirical setting for exploring adaptive information diffusion within groups. To effectively address potential dangers, a social group must swiftly communicate the threat throughout the collective while conserving energy in the event that the threat is unfounded. Through a combination of modeling, simulation, and empirical observations of alarm spread and damping patterns, we identified the behavioral rules governing this adaptive response. Experimental trials involving alarmed ant workers (Pogonomyrmex californicus) released into a tranquil group of nestmates revealed a consistent pattern of rapid alarm propagation followed by a comparatively extended decay period [1]. The experiments in [1] showed that individual ants exhibiting alarm behavior increased their movement speed, with variations in response to alarm stimuli, particularly during the peak of the reaction. We used the data in [1] to investigate whether these observed characteristics alone could account for the swift mobility increase and gradual decay of alarm excitement. Our self-propelled particle model incorporated a switch-like mechanism for ants' response to alarm signals and individual variations in the intensity of speed increased after encountering these signals. This study aligned with the established hypothesis that individual ants possess cognitive abilities to process and disseminate information, contributing to collective cognition within the colony (see [2] and the references therein). The elements examined in this research support this hypothesis by reproducing statistical features of the empirical speed distribution across various parameter values.

Antenna Cleaning Is Essential for Precise Behavioral Response to Alarm Pheromone and Nestmate-Non-Nestmate Discrimination in Japanese Carpenter Ants (Camponotus japonicus).

Self-grooming of the antennae is frequently observed in ants. This antennal maintenance behavior is presumed to be essential for effective chemical communication but, to our knowledge, this has not yet been well studied. When we removed the antenna-cleaning apparatuses of the Japanese carpenter ant (C. japonicus) to limit the self-grooming of the antennae, the worker ants demonstrated the self-grooming gesture as usual, but the antennal surface could not be sufficiently cleaned. By using scanning electron microscopy with NanoSuit, we observed the ants' antennae for up to 48 h and found that the antennal surfaces gradually became covered with self-secreted surface material. Concurrently, the self-grooming-limited workers gradually lost their behavioral responsiveness to undecane-the alarm pheromone. Indeed, their locomotive response to the alarm pheromone diminished for up to 24 h after the antenna cleaner removal operation. In addition, the self-grooming-limited workers exhibited less frequent aggressive behavior toward non-nestmate workers, and 36 h after the operation, approximately half of the encountered non-nestmate workers were accepted as nestmates. These results suggest that the antennal sensing system is affected by excess surface material; hence, their proper function is prevented until they are cleaned.

Nacre-like graphene oxide paper bonded with boric acid for fire early-warning sensor.

Boric acid-modified graphene oxide (GO-BA) paper is prepared by a green and facile water evaporation-induced self-assembly method, and its application as an early fire-alarm sensor is investigated. The nacre structure is constructed by assembling graphene oxide (GO) and boric acid (BA) as brick and mortar, respectively. Compared with pure GO paper, improved thermal-oxidative stability is obtained for GO-BA. GO nanosheets are bonded with BA molecules by forming hydrogen bonds between hydroxyl in BA and the rich oxygen-containing functional groups on GO. Notably, the insulating GO-BA paper can be rapidly thermally reduced to conductive reduced graphene oxide under flame exposure, thus providing an ideal fire-alarm response with a quick flame-detection time of ∼0.8 s. In addition, boron oxide formed under flame attack covers the surface of GO, inhibiting further oxidation of GO paper, and effectively extending the duration time of GO-BA under combustion. These results indicate that the GO-BA paper prepared has a broad prospect in the field of fire early-alarm.

Long-term study of behaviors of two cohabiting sea urchin species, Mesocentrotus nudus and Strongylocentrotus intermedius, under conditions of high food quantity and predation risk in situ.

BACKGROUND: In the predator-sea urchin-macrophyte trophic cascade, the ecological effect of sea urchins as grazers depends both on their density and the changes in foraging activity, which are influenced by various disturbing factors. However, the complete duration of the alarm reactions of echinoids has not been studied until now. Here, we tested a hypothesis that two cohabiting sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius, which differ morphologically, might display different behavioral responses to high hydrodynamic activity and predation. METHODS: We used continuous time-lapse video recording to clarify behavioral patterns of M. nudus and S. intermedius in presence of a large quantity of food (the kelp Saccharina japonica) but under different weather conditions and different types of predation threat: (1) calm weather conditions, (2) stormy weather conditions, (3) predation risk associated with the presence of several sea star species and (4) predation risk associated with an alarm stimulus (crushed conspecifics or heterospecifics). Three separate video recording experiments (134 days in total) were conducted under field conditions. Video recording analysis was performed to determine the number of specimens of each sea urchin species in the cameras' field of view, size of sea urchins' groups, movement patterns and the duration of the alarm responses of both sea urchin species. RESULTS: We showed that in the presence of kelp, M. nudus and S. intermedius exhibited both similar and different behavioral responses to hydrodynamics and predation threat. Under calm weather, movement patterns of both echinoids were similar but M. nudus exhibited the higher locomotion speed and distance traveled. Furthermore, S. intermedius but not M. nudus tended to group near the food substrate. The stormy weather caused a sharp decrease in movement activity followed by escape response in both echinoids. Six starfish species failed to predate on healthy sea urchins of either species and only a few attacks on ailing S. intermedius specimens were successful. The alarm response of S. intermedius lasted approximately 90 h and 20 h for starfish attacks on ailing conspecifics and for simulated attacks (crushed conspecifics or heterospecifics), respectively and involved several phases: (1) flight response, (2) grouping close to the food, (3) leaving the food and (4) return to the food. Phase three was the more pronounced in a case of starfish attack. M. nudus only responded to crushed conspecifics and exhibited no grouping behavior but displayed fast escape (during 4 h) and prolonged (up to 19 days) avoidance of the food source. This outcome is the longest alarm response reported for sea urchins. DISCUSSION: The most interesting finding is that two cohabiting sea urchin species, M. nudus and S. intermedius, display different alarm responses to predation threat. Both alarm responses are interpreted as defensive adaptations against visual predators.

Comparative chemical analysis of army ant mandibular gland volatiles (Formicidae: Dorylinae).

Army ants are keystone species in many tropical ecosystems. Yet, little is known about the chemical compounds involved in army ant communication. In the present study, we analyzed the volatile mandibular gland secretions-triggers of ant alarm responses-of six Neotropical army ant species of the genus Eciton (outgroup: Nomamyrmex esenbeckii). Using solid-phase microextraction, we identified 12 chemical compounds, primarily ketones with associated alcohols, one ester and skatole. Most compounds were shared among species, but their relative composition was significantly different. By comparing chemical distances of mandibular gland secretions to species divergence times, we showed that the secretions' compositions are not strictly determined by phylogeny. By identifying chemical bouquets of seven army ant species, our study provides a valuable comparative resource for future studies aiming to unveil the chemicals' precise role in army ant alarm communication.

Effects of cadmium on olfactory mediated behaviors and molecular biomarkers in coho salmon (Oncorhynchus kisutch).

The olfactory system of salmonids is sensitive to the adverse effects of metals such as copper and cadmium. In the current study, we analyzed olfactory-mediated alarm responses, epithelial injury and recovery, and a suite of olfactory molecular biomarkers encoding genes critical in maintaining olfactory function in juvenile coho salmon receiving acute exposures to cadmium (Cd). The molecular biomarkers analyzed included four G-protein coupled receptors (GPCRs) representing the two major classes of odorant receptors (salmon olfactory receptor sorb and vomeronasal receptors svra, svrb, and gpr27), as well as markers of neurite outgrowth (nrn1) and antioxidant responses to metals, including heme oxygenase 1 (hmox1), and peroxiredoxin 1 (prdx1). Coho received acute (8-168 h) exposures to 3.7 ppb and 347 ppb Cd, and a subset of fish was analyzed following a 16-day depuration. Coho exposed to 347 ppb Cd over 48 h exhibited a reduction in freeze responses, and an extensive loss of olfaction accompanied by histological injury to the olfactory epithelium. The olfactory injury in coho exposed to 347 ppb Cd was accompanied at the gene level by significant decreases in expression of the olfactory GPCRs and increased expression of hmox1. Persistent behavioral deficits, histological injury and altered expression of a subset of olfactory biomarkers were still evident in Cd-exposed coho following a 16-day depuration in clean water. Exposure to 3.7 ppb Cd also resulted in reduced freeze responses and histological changes to the olfactory epithelium within 48 h of Cd exposure, although the extent of olfactory injury was less severe than observed for fish in the high dose Cd group. Furthermore adverse behavioral effects were present in some coho receiving the low dose of Cd following a 16-day depuration. In summary, acute exposures to environmental levels of Cd can cause olfactory injury in coho salmon that may persist following depuration. Mechanism-based biomarkers of oxidative stress and olfactory structures can augment the evaluation of olfactory injury manifested at the physiological level.