Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-10 (of 10 Records) |
Query Trace: Strauch A[original query] |
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Effect of cooling on static postural balance while wearing firefighter's protective clothing in hot environment
Aljaroudi AM , Bhattacharya A , Strauch A , Quinn TD , Jon Williams W . Int J Occup Saf Ergon 2022 1-20 PURPOSE: Postural imbalance can result from hyperthermia mediated muscular fatigue and is a major factor contributing to injuries from falling. The objective of this study was to investigate the effect of exercise-induced hyperthermia and the impact of cooling on postural balance while wearing firefighters' protective clothing (FPC) in a hot environment. METHODS: A portable force platform measured postural balance characterized by postural sway patterns using center of pressure metrics. Twelve healthy, physically fit males were recruited to stand on the force platform once with eyes open and once with eyes closed before and after treadmill exercise (40% V˙O(2max)) inside an environmental chamber under hot and humid conditions (30 °C and 70% relative humidity) while wearing FPC. Subjects participated in two randomly assigned experimental phases: control and cooling intervention. RESULTS: A significant increase in physiological responses and postural balance metrics was observed after exercising in the heat chamber while wearing FPC. Cooling resulted in a significant effect only on postural sway speed after exercise-induced hyperthermia. CONCLUSIONS: Hyperthermia can negatively alter postural balance metrics, which may lead to an increased likelihood of falling. The utilization of body cooling reduced the thermal strain but had limited impact on postural balance stability. |
Probability of hyperthermia in a hot environment while wearing a liquid cooling garment underneath firefighters' protective clothing
Aljaroudi AM , Bhattacharya A , Yorio P , Strauch AL , Quinn TD , Williams WJ . J Occup Environ Hyg 2021 18 1-13 Firefighters' protective clothing (FPC) can limit human thermoregulation due to limited water vapor permeability and insulation. This study investigated the effect of cooling on the physiological responses and probability of hyperthermia in subjects wearing FPC during exercise in a hot environment. Twelve males participated in this study. A maximal graded treadmill exercise test was performed to measure maximal oxygen uptake (V̇O(2max)) and to assess subjects' capacity to perform the assigned exercise. Exercise included treadmill walking at 40% V̇O(2max) in warm (30 °C) and humid (70% RH) conditions for 40 min while wearing FPC. Subjects participated in two randomly counterbalanced assigned experimental protocols: control (no cooling) and intervention (cooling). The experimental intervention consisted of a cooling garment infused with cooled water (18 °C) through silastic tubing sewn into the fabric and worn underneath FPC. Each subject served as their own control and, therefore, completed both the control and intervention of the protocol. A logistic regression model was used to analyze the interaction effect of cooling on the probability of progression to hyperthermia (T(c) ≥ 38 °C). Subjects' physiological responses increased during exercise in a warm and humid environment. Active cooling decreased (p < 0.05) the thermal stress thereby reducing the probability of hyperthermia while exercising in hot and humid conditions. The results indicate that when cooling was used each subject, on average, was 91% less likely to reach the lower threshold limit of hyperthermia. Exercise in hot environments while wearing FPC results in significant physiological strain, which may lead to hyperthermia. Utilization of a cooling garment reduced physiological strain and the probability of hyperthermia. |
Effect of continuous cooling on inhibition and attention while wearing firefighter's PPE in a hot environment
Aljaroudi AM , Kadis DS , Bhattacharya A , Strauch A , Quinn TD , Williams WJ . J Occup Environ Hyg 2020 17 (5) 1-10 Firefighting is physically and mentally strenuous, requiring rapid, appropriate decision-making in hot environments. Intact cognitive function is imperative to firefighters' effectiveness and safety. The study purpose was to investigate the effect of hyperthermia and the effect of body cooling on sustained attention and response inhibition while wearing firefighters' personal protective ensembles after exercise in a hot environment. Twelve healthy males were recruited to participate in two randomly assigned exercise sessions (walking on a treadmill for 40 min at 40% [Formula: see text] O2max while wearing firefighter's protective ensemble) in a hot environment: control (no cooling) and intervention (cooling). For intervention sessions, a cooling garment was worn underneath firefighter's protective ensemble and infused with 18 degrees C water supplied by an external water circulator. Participants performed a computerized Go/No-Go (a measure of cognitive function) test three times at baseline and post-exercise for each experimental session. Participants completed baseline testing while wearing cotton athletic clothing. The exercise continued until the core temperature reached approximately 39 degrees C (for all subjects regardless of cooling or non-cooling experimental sessions). Following hyperthermia, participants' physiological responses were significantly increased after exercise. Subjects' reaction time was significantly reduced (improved) after experiencing thermal strain and reaching hyperthermia. The cooling method had a significant impact on suppressing the physiological load, i.e., body cooling delayed the time to reach a Tc of 39 degrees C (p </= 0.05), but not cognitive inhibition and attention (reaction time and accuracy). Unexpectedly, hyperthermia resulted in shorter reaction time following exercise (16.64 +/- 5.62; p < 0.03), likely influenced by increased attention/vigilance. Hyperthermia may trigger an acute increase in alertness, causing decreased reaction time. |
Heat stress assessment during intermittent work under different environmental conditions and clothing combinations of effective wet bulb globe temperature (WBGT)
Seo Y , Powell J , Strauch A , Roberge R , Kenny GP , Kim JH . J Occup Environ Hyg 2019 16 (7) 1-10 This study examined whether different combinations of ambient temperature and relative humidity for the effective wet bulb globe temperature, in conjunction with two different levels of clothing adjustment factors, elicit a similar level of heat strain consistent with the current threshold limit value guidelines. Twelve healthy, physically active men performed four 15-min sessions of cycling at a fixed rate of metabolic heat production of 350 watts. Each trial was separated by a 15-min recovery period under four conditions: (1) Cotton coveralls + dry condition (WD: 45.5 degrees C dry-bulb, 15% relative humidity); (2) Cotton coveralls + humid condition (WH: 31 degrees C dry-bulb, 84% relative humidity); (3) Protective clothing + dry condition (PD: 30 degrees C dry-bulb, 15% relative humidity); and (4) Protective clothing + humid condition (PH: 20 degrees C dry-bulb, 80% relative humidity). Gloves (mining or chemical) and headgear (helmet or powered air-purifying respirator) were removed during recovery with hydration ad libitum. Rectal temperature (Tre), skin temperature (Tsk), physiological heat strain (PSI), perceptual heat strain (PeSI), and body heat content were calculated. At the end of the 2-hr trials, Tre remained below 38 degrees C and the magnitude of Tre elevation was not greater than 1 degrees C in all conditions (WD: 0.9, WH: 0.8, WH: 0.7, and PD: 0.6 degrees C). However, Tsk was significantly increased by approximately 2.1 +/- 0.8 degrees C across all conditions (all p </= 0.001). The increase in Tsk was the highest in WD followed by PD, WH, and PH conditions (all p </= 0.001). Although PSI and PeSI did not indicate severe heat strain during the 2-hr intermittent work period, PSI and PeSI were significantly increased over time (p </= 0.001). This study showed that core temperature and heat strain indices (PSI and PeSI) increased similarly across the four conditions. However, given that core temperature increased continuously during the work session, it is likely that the American Conference of Governmental Industrial Hygienist's TLV((R)) upper limit core temperature of 38.0 degrees C may be surpassed during extended work periods under all conditions. |
Intestinal immune responses to type 2 oral polio vaccine (OPV) challenge in infants previously immunized with bivalent OPV and either high-dose or standard inactivated polio vaccine
Brickley EB , Strauch CB , Wieland-Alter WF , Connor RI , Lin S , Weiner JA , Ackerman ME , Arita M , Oberste MS , Weldon WC , Saez-Llorens X , Bandyopadhyay AS , Wright PF . J Infect Dis 2018 217 (3) 371-380 Background: The impact of inactivated polio vaccines (IPVs) on intestinal mucosal immune responses to live poliovirus is poorly understood. Methods: In a 2014 phase 2 clinical trial, Panamanian infants were immunized at 6, 10, and 14 weeks of age with bivalent oral polio vaccine (bOPV) and randomized to receive either a novel monovalent high-dose type 2-specific IPV (mIPV2HD) or a standard trivalent IPV at 14 weeks. Infants were challenged at 18 weeks with a monovalent type 2 oral polio vaccine (mOPV2). Infants' intestinal immune responses during the 3 weeks following challenge were investigated by measuring poliovirus type-specific neutralization and immunoglobulin (Ig) A, IgA1, IgA2, IgD, IgG, and IgM antibodies in stool samples. Results: Despite mIPV2HD's 4-fold higher type 2 polio D-antigen content and heightened serum neutralization profile, mIPV2HD-immunized infants' intestinal immune responses to mOPV2 challenge were largely indistinguishable from those receiving standard IPV. Mucosal responses were tightly linked to evidence of active infection and, in the 79% of participants who shed virus, robust type 2-specific IgA responses and stool neutralization were observed by 2 weeks after challenge. Conclusions: Enhancing IPV-induced serum neutralization does not substantively improve intestinal mucosal immune responses or limit viral shedding on mOPV2 challenge. Clinical Trials Registration: NCT02111135. |
Transfer of bacteriophage MS2 and fluorescein from N95 filtering facepiece respirators to hands: Measuring fomite potential
Brady TM , Strauch AL , Almaguer CM , Niezgoda G , Shaffer RE , Yorio PL , Fisher EM . J Occup Environ Hyg 2017 14 (11) 0 Contact transmission of pathogens from personal protective equipment is a concern within the healthcare industry. During public health emergency outbreaks, resources become constrained and the reuse of personal protective equipment, such as N95 filtering facepiece respirators, may be needed. This study was designed to characterize the transfer of bacteriophage MS2 and fluorescein between filtering facepiece respirators and the wearer's hands during three simulated use scenarios. Filtering facepiece respirators were contaminated with MS2 and fluorescein in droplets or droplet nuclei. Thirteen test subjects performed filtering facepiece respirator use scenarios including improper doffing, proper doffing and reuse, and improper doffing and reuse. Fluorescein and MS2 contamination transfer were quantified. The average MS2 transfer from filtering facepiece respirators to the subjects' hands ranged from 7.6-15.4% and 2.2-2.7% for droplet and droplet nuclei derived contamination, respectively. Handling filtering facepiece respirators contaminated with droplets resulted in higher levels of MS2 transfer compared to droplet nuclei for all use scenarios (p = 0.007). MS2 transfer from droplet contaminated filtering facepiece respirators during improper doffing and reuse was greater than transfer during improper doffing (p = 0.008) and proper doffing and reuse (p = 0.042). Droplet contamination resulted in higher levels of fluorescein transfer compared to droplet nuclei contaminated filtering facepiece respirators for all use scenarios (p = 0.009). Fluorescein transfer was greater for improper doffing and reuse (p = 0.007) from droplet contaminated masks compared to droplet nuclei contaminated filtering facepiece respirators and for improper doffing and reuse when compared improper doffing (p = 0.017) and proper doffing and reuse (p = 0.018) for droplet contaminated filtering facepiece respirators. For droplet nuclei contaminated filtering facepiece respirators, the difference in MS2 and fluorescein transfer did not reach statistical significance when comparing any of the use scenarios. The findings suggest that the results of fluorescein and MS2 transfer were consistent and highly correlated across the conditions of study. The data supports CDC recommendations for using proper doffing techniques and discarding filtering facepiece respirators that are directly contaminated with secretions from a cough or sneeze. |
Physiological evaluation of cooling devices in conjunction with personal protective ensembles recommended for use in West Africa
Quinn T , Kim JH , Strauch A , Wu T , Powell J , Roberge R , Shaffer R , Coca A . Disaster Med Public Health Prep 2017 11 (5) 1-7 OBJECTIVE: Cooling devices (CDs) worn under personal protective equipment (PPE) can alleviate some of the heat stress faced by health care workers responding to the Ebola outbreak in West Africa. METHODS: Six healthy, young individuals were tested while wearing 4 different CDs or no cooling (control) under PPE in an environmental chamber (32 degrees C/92% relative humidity) while walking (3 METs, 2.5 mph, 0% grade) on a treadmill for 60 minutes. Exercise was preceded by a 15-minute stabilization period and a 15-minute donning period. RESULTS: The control condition resulted in a significantly higher rectal temperature (Tre) at the end of the exercise than did all CD conditions (CD1, P=0.004; CD2, P=0.01; CD3, P=0.000; CD4, P=0.000) with CD1 and CD2 resulting in a higher Tre than CD3 and CD4 (P<0.05). The control condition resulted in a higher heart rate (HR) at the end of exercise than did the CD3 (P=0.01) and CD4 (P=0.009) conditions, whereas the HR of the CD1 and CD2 conditions was higher than that of the CD3 and CD4 conditions (P<0.05). Weight loss in the control condition was higher than in the CD3 (P=0.003) and CD4 (P=0.01) conditions. Significant differences in subjective measurements of thermal stress were found across conditions and time. CONCLUSIONS: Use of CDs can be advantageous in decreasing the negative physiological and subjective responses to the heat stress encountered by health care workers wearing PPE in hot and humid environments. (Disaster Med Public Health Preparedness. 2017;page 1 of 7). |
Evaluation of gowns and coveralls used by medical personnel working with ebola patients against simulated bodily fluids using an elbow lean test
Jaques PA , Gao P , Kilinc-Balci S , Portnoff L , Weible R , Horvatin M , Strauch A , Shaffer R . J Occup Environ Hyg 2016 13 (11) 1-37 Gowns and coveralls are important components of protective ensembles used during the management of known or suspected Ebola patients. In this study, an Elbow Lean Test was used to obtain a visual semi-quantitative measure of the resistance of medical protective garments to the penetration of two bodily fluid simulants. Tests were done on swatches of continuous and discontinuous regions of fabrics cut from five gowns and four coveralls at multiple elbow pressure levels (2 - 44 PSI). Swatches cut from the continuous regions of one gown and two coveralls did not have any strike-through. For discontinuous regions, only the same gown consistently resisted fluid strike-through. As hypothesized, with the exception of one garment, fluid strike-through increased with higher applied elbow pressure, was higher for lower fluid surface tension, and was higher for the discontinuous regions of the protective garments. |
Assessing the Efficacy of Tabs on Filtering Facepiece Respirator Straps to Increase Proper Doffing Techniques While Reducing Contact Transmission of Pathogens
Strauch AL , Brady TM , Niezgoda G , Almaguer CM , Shaffer RE , Fisher EM . J Occup Environ Hyg 2016 13 (10) 794-801 NIOSH-certified N95 filtering facepiece respirators (FFRs) are used in healthcare settings as a control measure to mitigate exposures to airborne infectious particles. When the outer surface of an FFR becomes contaminated, it presents a contact transmission risk to the wearer. The Centers for Disease Control and Prevention (CDC) guidance recommends that healthcare workers (HCWs) doff FFRs by grasping the straps at the back of the head to avoid contact with the potentially contaminated surface. Adherence to proper doffing technique is reportedly low due to numerous factors including difficulty in locating and grasping the straps. This study compares the impact of tabs placed on FFR straps to controls (without tabs) on proper doffing, ease of use and comfort, and reduction of transfer of contamination to the wearer. Utilizing a fluorescent agent as a tracer to track contamination from FFRs to hand and head areas of 20 human subjects demonstrated that there was no difference in tabbed FFR straps and controls with respect to promoting proper doffing (p = 0.48), but did make doffing easier (p = 0.04) as indicated by 7 of 8 subjects that used the tabs. Seven of the 20 subjects felt that FFRs with tabs were easier to remove, while only 2 of 20 indicated that FFRs without tabs were easier to remove. Discomfort was not a factor for either FFR strap type. When removing an FFR with contaminated hands, the use of the tabs significantly reduced the amount of tracer transfer compared to straps without tabs (p = 0.012). FFRs with tabs on the straps are associated with ease of doffing and significantly less transfer of the fluorescent tracer. |
Spread of a distinct Stx2-encoding phage prototype among Escherichia coli O104:H4 strains from outbreaks in Germany, Norway, and Georgia
Beutin L , Hammerl JA , Strauch E , Reetz J , Dieckmann R , Kelner-Burgos Y , Martin A , Miko A , Strockbine NA , Lindstedt BA , Horn D , Monse H , Huettel B , Muller I , Stuber K , Reinhardt R . J Virol 2012 86 (19) 10444-55 Shiga toxin 2 (Stx2)-producing Escherichia coli (STEC) O104:H4 caused one of the world's largest outbreaks of hemorrhagic colitis and hemolytic uremic syndrome in Germany in 2011. These strains have evolved from enteroaggregative E. coli (EAEC) by the acquisition of the Stx2 genes and have been designated enteroaggregative hemorrhagic E. coli. Nucleotide sequencing has shown that the Stx2 gene is carried by prophages integrated into the chromosome of STEC O104:H4. We studied the properties of Stx2-encoding bacteriophages which are responsible for the emergence of this new type of E. coli pathogen. For this, we analyzed Stx bacteriophages from STEC O104:H4 strains from Germany (in 2001 and 2011), Norway (2006), and the Republic of Georgia (2009). Viable Stx2-encoding bacteriophages could be isolated from all STEC strains except for the Norwegian strain. The Stx2 phages formed lysogens on E. coli K-12 by integration into the wrbA locus, resulting in Stx2 production. The nucleotide sequence of the Stx2 phage P13374 of a German STEC O104:H4 outbreak was determined. From the bioinformatic analyses of the prophage sequence of 60,894 bp, 79 open reading frames were inferred. Interestingly, the Stx2 phages from the German 2001 and 2011 outbreak strains were found to be identical and closely related to the Stx2 phages from the Georgian 2009 isolates. Major proteins of the virion particles were analyzed by mass spectrometry. Stx2 production in STEC O104:H4 strains was inducible by mitomycin C and was compared to Stx2 production of E. coli K-12 lysogens. |
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