Slow Breathing Reduces Markers of Stress in Response to a Virtual-Reality Active Shooter Training Drill

Law enforcement officers are expected to respond to potential life-threatening scenarios in high stress environments. Acute participation in virtual reality (VR) active shooter scenarios has been shown to increase markers of stress. Tactical occupations (i.e., military, law enforcement personnel) are trained to use slow breathing methods to aid in stress reduction, but there is no known evidence supporting the effectiveness of slow breathing in relation to a VR-active shooter training drill (VR-ASD). PURPOSE: To determine the effects of slow breathing on markers of stress in response to a VR-ASD. METHODS: A parallel between subjects design was used, during which, eighty-one (n=81) subjects performed five minutes of either slow breathing method 1 (SB1), slow breathing method 2 (SB2), or no modified breathing [normal breathing (NB)] immediately pre and post VR-ASD. SB1 (i.e., box breathing) involved a four second inhalation, two second pause, four second exhalation, and a two second pause. SB2 involved a four second inhalation, followed by a two second exhalation. The VR-ASD (~1 minute) included a single gunman and simulated victims. Subjects were fitted with a VR headset and equipped with a Glock 17 training pistol. Salivary samples and heart rate (HR) were collected thirty minutes pre, five minutes pre, five minutes post, and thirty minutes post VR-ASD. Saliva was analyzed for stress markers: α-amylase (AA) and secretory immunoglobulin-A (Sig-A). AA and SIgA were analyzed via 3x4 (treatment x timepoint) factorial ANOVAs. HR was analyzed via 2x4 factorial ANOVA. RESULTS: Both methods of slow breathing (SB1 and SB2) resulted in significantly lower AA concentrations at five (p \u3c 0.001), and thirty-minutes post VR-ASD (SB1: p= 0.008; SB2: p \u3c 0.001) compared to NB. In the NB condition, AA concentrations were significantly elevated five minutes post VR-ASD (p \u3c 0.001) compared to all other timepoints but did not change across time in SB1 or SB2 (p \u3e .05). A significant increase in SIgA concentrations was noted five minutes post VR-ASD compared to all the other time points (p \u3c 0.001), and significantly higher SIgA concentrations were found in the NB compared to SB1 and SB2 (p\u3c0.001). Finally, slow breathing resulted in a significant decrease in HR from pre to post VR-ASD (p \u3c 0.05). CONCLUSION: The VR-ASD resulted in a significant increase in stress markers AA and SIgA. Slow breathing (both SB1 and SB2) prevented a significant increase in AA concentrations and resulted in lower concentrations post VR-ASD. Future studies should investigate the effects of longitudinal participation in slow breathing methods on markers of stress in response to a VR-ASD

Physiological Stress Responses to a Live-Fire Training Evolution in Career Firefighters

Firefighters have a physically demanding job that exposes them to many specific and unique stressors, which contribute to cardiovascular disease (CVD) risk (i.e., cardiovascular strain, inflammation, and oxidative stress) or even mortality. At present, the literature lacks data evaluating these physiological stress responses amongst firefighters in any realistic or simulated scenarios, such as a live-fire training evolution (LFTE). Given the elevated risk of premature mortality, there is a critical need to better understand the physiological stress responses to an LFTE. This information could aid in developing nutritional, training, and other various interventions to mitigate stress load and reduce the incidence of CVD among this population. PURPOSE: To assess the physiological stress response to an LFTE among firefighters. METHODS: Seventy-six (n = 76) career firefighters completed an LFTE. Salivary samples were collected pre, immediately post, and 30-min post the LFTE, and analyzed the following stress markers: α-amylase (AA), secretory immunoglobulin-A (SIgA), and cortisol. One-way repeated measures analysis of variance was used to assess changes over time. Fisher’s LSD and Cohen’s d effect size calculations were used for Post hoc analysis. RESULTS: Significant main effects for time were found for AA, SIgA, and cortisol (p\u3c0.001). Fisher’s LSD post hoc analysis found AA, SIgA, and cortisol concentrations were all significantly elevated immediately post LFTE compared to pre (p\u3c0.0001) and 30-min post (p\u3c0.0001). Medium to large effect sizes were noted for AA, SIgA, and cortisol with respect to changes pre to immediately post-LFTE (d = 0.84, 0.61, and 0.78, respectively). CONCLUSION: While many studies have shown increased inflammation and oxidative stress, as well as adverse cardiovascular and metabolic responses to firefighting activities, these data provide insight into the physiological stress placed upon a firefighter engaging in fire-suppressive evolutions

Bacteriophage Lysin Mediates the Binding of Streptococcus mitis to Human Platelets through Interaction with Fibrinogen

The binding of bacteria to human platelets is a likely central mechanism in the pathogenesis of infective endocarditis. We have previously found that platelet binding by Streptococcus mitis SF100 is mediated by surface components encoded by a lysogenic bacteriophage, SM1. We now demonstrate that SM1-encoded lysin contributes to platelet binding via its direct interaction with fibrinogen. Far Western blotting of platelets revealed that fibrinogen was the major membrane-associated protein bound by lysin. Analysis of lysin binding with purified fibrinogen in vitro confirmed that these proteins could bind directly, and that this interaction was both saturable and inhibitable. Lysin bound both the Aα and Bβ chains of fibrinogen, but not the γ subunit. Binding of lysin to the Bβ chain was further localized to a region within the fibrinogen D fragment. Disruption of the SF100 lysin gene resulted in an 83±3.1% reduction (mean ± SD) in binding to immobilized fibrinogen by this mutant strain (PS1006). Preincubation of this isogenic mutant with purified lysin restored fibrinogen binding to wild type levels. When tested in a co-infection model of endocarditis, loss of lysin expression resulted in a significant reduction in virulence, as measured by achievable bacterial densities (CFU/g) within vegetations, kidneys, and spleens. These results indicate that bacteriophage-encoded lysin is a multifunctional protein, representing a new class of fibrinogen-binding proteins. Lysin appears to be cell wall-associated through its interaction with choline. Once on the bacterial surface, lysin can bind fibrinogen directly, which appears to be an important interaction for the pathogenesis of endocarditis

Impact of L-theanine and L-tyrosine on markers of stress and cognitive performance in response to a virtual reality based active shooter training drill

Ingestion of L-theanine and L-tyrosine has been shown to reduce salivary stress biomarkers and improve aspects of cognitive performance in response to stress. However, there have been no studies to concurrently examine the impact of both L-theanine and L-tyrosine ingestion during a mental stress challenge (MSC) involving a brief cognitive challenge and a virtual reality based active shooter training drill. Thus, the purpose of this study was to determine the impact of ingestion of L-theanine and L-tyrosine on markers of stress and cognitive performance in response to a virtual reality active shooter drill and cognitive challenge. The cognitive challenge involved a Stroop challenge and mental arithmetic. Eighty subjects (age = 21 ± 2.6 yrs; male = 46; female = 34) were randomly assigned L-tyrosine (n = 28; 2000 mg), L-theanine (n = 25; 200 mg), or placebo (n = 27) prior to MSC exposure. Saliva samples, state-anxiety inventory (SAI) scales, and heart rate (HR) were collected before and after exposure to the MSC. Saliva was analyzed for stress markers α-amylase (sAA) and secretory immunoglobulin A (SIgA). The MSC resulted in significant increases in sAA, SIgA, HR, and SAI. Ingestion of L-theanine and L-tyrosine did not impact markers of stress. However, the L-tyrosine treatment demonstrated significantly lower missed responses compared to the placebo treatment group during the Stroop challenge. These data demonstrate that ingestion of L-theanine or L-tyrosine does not impact markers of stress in response to a MSC but may impact cognitive performance. This study was pre-registered as a clinical trial ("Impact of supplements on stress markers”: NCT05592561)

Slow Breathing Reduces Biomarkers of Stress in Response to a Virtual Reality Active Shooter Training Drill

Tactical occupations regularly encounter life-threatening situations while on duty. Although these occupations are often trained to utilize slow breathing (SB) during intense stress, there is no evidence supporting the effects on markers of stress in response to a virtual reality active shooter training drill (VR-ASD). The purpose of the study was to determine the impact of acute SB on biomarkers of stress in response to a VR-ASD. Seventy-nine (n = 79) subjects performed either slow breathing method 1 (SB1), slow breathing method 2 (SB2), or normal breathing (control) for five minutes, both pre- and post-VR-ASD. Saliva samples were analyzed for stress markers, including α-amylase (sAA) and secretory immunoglobulin-A (SIgA). Both methods of SB resulted in significantly lower sAA concentrations at 5 (p p = 0.008; SB2: p p p > 0.05). Thus, both SB1 and SB2 reduced the sAA response and resulted in lower concentrations post-VR-ASD. This study was pre-registered as a clinical trial (“Impact of Breathing Interventions on Stress Markers”; NCT05825846)

Forage Mass and Nutritive Value of Grain- and Forage-Type Soybean Cultivars Managed under Different Row Spacings and Clipping Heights

Soybean (Glycine max L.) is a high value crop that has been used as a forage since the early 1900s in the southern U.S. (e.g., Mississippi, Alabama, Georgia, South Carolina, and Florida). Renewed interest has increased the use of soybean as a viable and economical high protein alternative to forage growers in the southern region. The objective of this study was to determine herbage mass (HM) and nutritive value of forage soybean managed under two row spacing (36 and 72 cm) and three stubble heights (10, 15, and 20 cm). Five cultivars were used ‘Stonewall’, ‘Laredo’, ‘Tower of Leaves’, Asgrow® ‘AG64X8’, and Asgrow® ‘AG79X9’ and sown at two locations (Shorter and Headland, AL). Forage was harvested in July and August during both years and HM was determined. Crude protein (CP) and fiber fractions were determined using near-infrared spectroscopy. Years and location did vary, but overall, Stonewall had the greatest (p −1) with a high nutritive value (124 g CP kg−1, 449 g NDF kg−1, and 372 g ADF kg−1). Laredo had the lowest HM (1169 kg DM ha−1; p −1; p −1; 331 g ADF kg−1; 413 g NDF kg−1; p = 0.001) compared to 20 cm (179, 282, and 375 g kg−1 for CP, ADF, and NDF, respectively). Row spacing did not consistently influence either HM or nutritive values. Due to its relatively good nutritive value and HM, forage soybean should be considered as a monoculture or in a mixed sward with other warm-season annual forages for inclusion in forage-based livestock diets

A National Status Report on United States Coral Reefs Based on 2012-2018 Data From National Oceanic and Atmospheric Administration's National Coral Reef Monitoring Program

National Oceanic and Atmospheric Administration's Coral Reef Conservation Program supports the National Coral Reef Monitoring Program (NCRMP) in the United States Pacific, Atlantic, Caribbean, and Gulf of Mexico. NCRMP conducts standardized observations of biological, climatic, and socioeconomic indicators across American Samoa, Guam, the Main Hawaiian Islands, the Northwestern Hawaiian Islands, the Northern Mariana Islands, the Pacific Remote Islands, Florida, the Flower Garden Banks, Puerto Rico, and the United States Virgin Islands. NCRMP provides periodic, national-level assessments of the status of United States coral reef ecosystems and communities connected to them. In 2014, NCRMP partnered with the University of Maryland Center for Environmental Science on an unprecedented collaboration between federal and jurisdictional/state agencies, academia, and non-governmental organizations to synthesize NCRMP data into a reporting format designed to be accessible and relevant to the public and policy makers. The process involved multi-year data analyses of key benthic, fish, and climate indicators. In populated jurisdictions, socioeconomic data were integrated to assess public support for management actions, participation in pro-environmental behaviors, and awareness of threats to coral reefs. Jurisdictions were scored using a report-card scale (0-100%) by establishing references for each indicator using best-available historical data or expert opinion where historical data did not exist or were not statistically comparable. Despite overall ecosystem scores of Fair for all combined Atlantic (70%) and Pacific (74%) jurisdictions, the current trend is downward with a majority of United States coral reefs declining and vulnerable to further degradation. Remote, uninhabited reefs had an advantage with respect to reef fish population scores, i.e., Flower Garden Banks (85%) and Pacific Remote Islands (93%), when compared to populated location scores, i.e., Puerto Rico (63%) and Main Hawaiian Islands (66%). All coral reefs are highly impacted by climate change, and climate impacts were more pronounced than expected on remote reefs, i.e., the Northwestern Hawaiian Islands (58%). Presenting results in a report-card style facilitates communication to the public and policy makers, and provides a useful mechanism to garner support for management actions such as expanding protected areas; enforcing existing regulations; increasing climate change education; reducing land-based sources of pollution; and other actions to improve the trajectory of coral reef ecosystem conditions