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  1. Article ; Online: Identifying the Optimal Heat Exposure Metric for Predicting the Physiological Response to Dry or Humid Heat Stress in Young and Older Adults: A Randomized Controlled Study.

    Foster, Josh / McKenna, Zachary J / Atkins, Whitey C / Jarrard, Caitlin P / Crandall, Craig G

    Environmental health perspectives

    2024  Volume 132, Issue 1, Page(s) 17701

    MeSH term(s) Humans ; Aged ; Aging/physiology ; Hot Temperature ; Heat Stress Disorders ; Heat-Shock Response/physiology ; Humidity
    Language English
    Publishing date 2024-01-12
    Publishing country United States
    Document type Randomized Controlled Trial ; Journal Article
    ZDB-ID 195189-0
    ISSN 1552-9924 ; 0091-6765 ; 1078-0475
    ISSN (online) 1552-9924
    ISSN 0091-6765 ; 1078-0475
    DOI 10.1289/EHP13733
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Aging Increases Enterocyte Damage during a 3-Hour Exposure to Very Hot and Dry Heat: A Preliminary Study

    Foster, Josh / Mckenna, Zachary J. / Atkins, Whitley C. / Jarrard, Caitlin P. / Crandall, Craig G.

    Biology (Basel). 2023 Aug. 04, v. 12, no. 8

    2023  

    Abstract: Profound heat stress can damage the gastrointestinal barrier, leading to microbial translocation from the gut and subsequent systemic inflammation. Despite the greater vulnerability of older people to heat wave-related morbidity and mortality, it is ... ...

    Abstract Profound heat stress can damage the gastrointestinal barrier, leading to microbial translocation from the gut and subsequent systemic inflammation. Despite the greater vulnerability of older people to heat wave-related morbidity and mortality, it is unknown if age modulates gastrointestinal barrier damage and inflammation during heat stress. Therefore, the aim of this study was to determine if aging impacted enterocyte damage and systemic inflammatory responses to a 3-h exposure to very hot and dry (47 °C, 15% humidity) heat with accompanying activities of daily living (intermittent activity at 3 METS). Data from 16 young (age 21 to 39 years) and 16 older (age 65 to 76 years) humans were used to address this aim. In each group, log-transformed plasma concentrations of intestinal fatty acid binding protein (I-FABPₗₒg), interleukin-8 (IL-8ₗₒg), and tissue factor (TFₗₒg) were assessed as indices of enterocyte damage, systemic inflammation, and blood coagulation, respectively, before and after the 3-h heat exposure. In the younger cohort, I-FABPₗₒg concentration did not increase from pre to post heat exposure (p = 0.264, d = 0.20), although it was elevated in the older group (p = 0.014, d = 0.67). The magnitude of the increase in I-FABPₗₒg was greater in the older participants (p = 0.084, d = 0.55). Across all participants, there was no correlation between the change in core temperature and the change in IFABPₗₒg. There was no change in IL-8ₗₒg in the younger group (p = 0.193, d = 0.23) following heat exposure, but we observed a decrease in IL-8ₗₒg in the older group (p = 0.047, d = 0.48). TFₗₒg decreased in the younger group (p = 0.071, d = 0.41), but did not change in the older group (p = 0.193, d = 0.15). Our data indicate that I-FABPₗₒg concentration (an index of enterocyte damage) is increased in older humans during a 3-h extreme heat exposure. Future studies should determine whether this marker reflects increased gastrointestinal barrier permeability in older individuals during heat exposure.
    Keywords blood coagulation ; fatty acids ; heat ; heat stress ; humidity ; inflammation ; interleukin-8 ; intestines ; morbidity ; mortality ; people ; permeability ; temperature
    Language English
    Dates of publication 2023-0804
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article ; Online
    ZDB-ID 2661517-4
    ISSN 2079-7737
    ISSN 2079-7737
    DOI 10.3390/biology12081088
    Database NAL-Catalogue (AGRICOLA)

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  3. Article: Aging Increases Enterocyte Damage during a 3-Hour Exposure to Very Hot and Dry Heat: A Preliminary Study.

    Foster, Josh / Mckenna, Zachary J / Atkins, Whitley C / Jarrard, Caitlin P / Crandall, Craig G

    Biology

    2023  Volume 12, Issue 8

    Abstract: Profound heat stress can damage the gastrointestinal barrier, leading to microbial translocation from the gut and subsequent systemic inflammation. Despite the greater vulnerability of older people to heat wave-related morbidity and mortality, it is ... ...

    Abstract Profound heat stress can damage the gastrointestinal barrier, leading to microbial translocation from the gut and subsequent systemic inflammation. Despite the greater vulnerability of older people to heat wave-related morbidity and mortality, it is unknown if age modulates gastrointestinal barrier damage and inflammation during heat stress. Therefore, the aim of this study was to determine if aging impacted enterocyte damage and systemic inflammatory responses to a 3-h exposure to very hot and dry (47 °C, 15% humidity) heat with accompanying activities of daily living (intermittent activity at 3 METS). Data from 16 young (age 21 to 39 years) and 16 older (age 65 to 76 years) humans were used to address this aim. In each group, log-transformed plasma concentrations of intestinal fatty acid binding protein (I-FABP
    Language English
    Publishing date 2023-08-04
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2661517-4
    ISSN 2079-7737
    ISSN 2079-7737
    DOI 10.3390/biology12081088
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Sex Differences in Sympathetic Responses to Lower Body Negative Pressure.

    Jarrard, Caitlin P / Watso, Joseph C / Atkins, Whitley C / McKenna, Zachary J / Foster, Josh / Huang, Mu / Belval, Luke N / Crandall, Craig G

    Medicine and science in sports and exercise

    2024  

    Abstract: Introduction: Trauma-induced hemorrhage is a leading cause of death in prehospital settings. Experimental data demonstrate that females have a lower tolerance to simulated hemorrhage (i.e., central hypovolemia). However, the mechanism(s) underpinning ... ...

    Abstract Introduction: Trauma-induced hemorrhage is a leading cause of death in prehospital settings. Experimental data demonstrate that females have a lower tolerance to simulated hemorrhage (i.e., central hypovolemia). However, the mechanism(s) underpinning these responses are unknown. Therefore, this study aimed to compare autonomic cardiovascular responses during central hypovolemia between the sexes. We hypothesized that females would have a lower tolerance and smaller increase in muscle sympathetic nerve activity (MSNA) to simulated hemorrhage.
    Methods: Data from 17 females and 19 males, aged 19-45, were retrospectively analyzed. Participants completed a progressive lower-body negative pressure (LBNP) protocol to presyncope to simulate hemorrhagic tolerance with continuous measures of MSNA and beat-to-beat hemodynamic variables. We compared responses at baseline, at two LBNP stages (40 mmHg and 50 mmHg), and at immediately before presyncope. In addition, we compared responses at relative percentages (33%, 66%, and 100%) of hemorrhagic tolerance, calculated via the cumulative stress index (i.e., the sum of the product of time and pressure at each LBNP stage).
    Results: Females had lower tolerance to central hypovolemia (female: 561 ± 309 vs. male: 894 ± 304 min*mmHg [time*LBNP]; p = 0.003). At LBNP 40 mmHg and 50 mmHg, females had lower diastolic blood pressures (main effect of sex: p = 0.010). For the relative LBNP analysis, females exhibited lower MSNA burst frequency (main effect of sex: p = 0.016) accompanied by a lower total vascular conductance (sex: p = 0.028; main effect of sex).
    Conclusions: Females have a lower tolerance to central hypovolemia, which was accompanied by lower diastolic blood pressure at 40 and 50 mmHg LBNP. Notably, females had attenuated MSNA responses when assessed as relative LBNP tolerance time.
    Language English
    Publishing date 2024-01-18
    Publishing country United States
    Document type Journal Article
    ZDB-ID 603994-7
    ISSN 1530-0315 ; 0195-9131 ; 0025-7990
    ISSN (online) 1530-0315
    ISSN 0195-9131 ; 0025-7990
    DOI 10.1249/MSS.0000000000003392
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Effect of a Single Session of Intermittent Hypoxia on Erythropoietin and Oxygen-Carrying Capacity.

    Nagel, Mercedes J / Jarrard, Caitlin P / Lalande, Sophie

    International journal of environmental research and public health

    2020  Volume 17, Issue 19

    Abstract: Intermittent hypoxia, defined as alternating bouts of breathing hypoxic and normoxic air, has the potential to improve oxygen-carrying capacity through an erythropoietin-mediated increase in hemoglobin mass. The purpose of this study was to determine the ...

    Abstract Intermittent hypoxia, defined as alternating bouts of breathing hypoxic and normoxic air, has the potential to improve oxygen-carrying capacity through an erythropoietin-mediated increase in hemoglobin mass. The purpose of this study was to determine the effect of a single session of intermittent hypoxia on erythropoietin levels and hemoglobin mass in young healthy individuals. Nineteen participants were randomly assigned to an intermittent hypoxia group (Hyp,
    MeSH term(s) Adult ; Erythrocytes/metabolism ; Erythropoietin/blood ; Erythropoietin/metabolism ; Female ; Hemoglobins/analysis ; Humans ; Hypoxia/blood ; Hypoxia/physiopathology ; Male ; Oxygen/blood ; Oxygen/metabolism ; Oxygen Consumption
    Chemical Substances Hemoglobins ; Erythropoietin (11096-26-7) ; Oxygen (S88TT14065)
    Language English
    Publishing date 2020-10-04
    Publishing country Switzerland
    Document type Journal Article ; Randomized Controlled Trial
    ISSN 1660-4601
    ISSN (online) 1660-4601
    DOI 10.3390/ijerph17197257
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Hypoxic preconditioning attenuates ischemia-reperfusion injury in young healthy adults.

    Jarrard, Caitlin P / Nagel, Mercedes J / Stray-Gundersen, Sten / Tanaka, Hirofumi / Lalande, Sophie

    Journal of applied physiology (Bethesda, Md. : 1985)

    2021  Volume 130, Issue 3, Page(s) 846–852

    Abstract: Ischemic preconditioning attenuates the reduction in brachial artery endothelial function following an ischemia-reperfusion injury. Brief bouts of systemic hypoxemia could similarly mitigate the blunted vasodilatory response induced by an ischemia- ... ...

    Abstract Ischemic preconditioning attenuates the reduction in brachial artery endothelial function following an ischemia-reperfusion injury. Brief bouts of systemic hypoxemia could similarly mitigate the blunted vasodilatory response induced by an ischemia-reperfusion injury. The aim of the present study was to determine whether an acute bout of intermittent hypoxia protects against an ischemia-reperfusion injury in young healthy individuals. Brachial artery endothelial function was assessed by flow-mediated dilation in 16 young healthy individuals before and after a 20-min upper arm blood flow occlusion to induce ischemia-reperfusion injury. Blood flow occlusion was preceded by either intermittent hypoxia or intermittent normoxia. Intermittent hypoxia consisted of three 4-min hypoxic cycles at an arterial oxygen saturation of 87 ± 3% separated by 4-min normoxic cycles. Intermittent hypoxia resulted in a lower arterial oxygen saturation than intermittent normoxia (hypoxia: 87 ± 3% vs. normoxia: 99 ± 1%,
    MeSH term(s) Adult ; Brachial Artery ; Humans ; Hypoxia ; Ischemic Preconditioning ; Reperfusion Injury ; Vasodilation
    Language English
    Publishing date 2021-01-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 219139-8
    ISSN 1522-1601 ; 0021-8987 ; 0161-7567 ; 8750-7587
    ISSN (online) 1522-1601
    ISSN 0021-8987 ; 0161-7567 ; 8750-7587
    DOI 10.1152/japplphysiol.00772.2020
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Reduced resting beat-to-beat blood pressure variability in females with relapsing-remitting multiple sclerosis.

    Kissell, Claire E / Young, Benjamin E / Jarrard, Caitlin P / Huang, Mu / Allen, Dustin R / Okuda, Darin T / Smith, Scott A / Fadel, Paul J / Davis, Scott L

    Multiple sclerosis and related disorders

    2023  Volume 83, Page(s) 105416

    Abstract: Background: Relapsing-remitting multiple sclerosis (RRMS) is a demyelinating disease of the central nervous system and cardiovascular autonomic dysfunction has been well documented in this population. The sympathetic nervous system contributes to beat- ... ...

    Abstract Background: Relapsing-remitting multiple sclerosis (RRMS) is a demyelinating disease of the central nervous system and cardiovascular autonomic dysfunction has been well documented in this population. The sympathetic nervous system contributes to beat-to-beat blood pressure regulation primarily by baroreflex control of the peripheral vasculature which may be impaired in females with RRMS. Even at rest, attenuated sympathetic control of vasomotor tone may result in large and frequent blood pressure excursions (i.e., greater blood pressure variability). Therefore, the primary purpose of this investigation was to test the following hypotheses; (1) females with RRMS have augmented beat-to-beat blood pressure variability compared to healthy controls and (2) reduced sympathetic baroreflex sensitivity in females with RRMS is related to augmented blood pressure variability.
    Methods: Electrocardiogram and beat-to-beat blood pressure were continuously recorded during 8-10 min of supine rest in 26 females with clinically definite RRMS and 24 sex-, age- and BMI- matched healthy controls. Muscle sympathetic nerve activity (MSNA) was recorded in a subset of participants (MS, n = 15; CON, n = 14). Traditional statistical measurements of dispersions were used to index beat-to-beat blood pressure variability. Spontaneous sympathetic baroreflex sensitivity was quantified by sorting diastolic blood pressures into 3 mmHg bins and calculating MSNA burst incidence within each bin. Weighted linear regression was then used to account for the number of cardiac cycles in each bin and calculate slopes. Spontaneous cardiac baroreflex sensitivity was determined using the sequence method.
    Results: Groups had similar resting mean arterial pressure (MAP), systolic blood pressure (SBP), diastolic blood pressure (DBP), MSNA burst frequency and MSNA burst incidence (All P > 0.05). The standard deviation and interquartile range of MAP, SBP and DBP were less in females with RRMS compared to healthy controls (All P < 0.05). There were no between groups differences in sympathetic baroreflex sensitivity or cardiac baroreflex sensitivity (Both P > 0.05) and baroreflex sensitivity measures were not related to any indices of blood pressure variability (Both P > 0.05).
    Conclusion: These data suggest that females with RRMS have reduced beat-to-beat blood pressure variability. However, this does not appear to be related to changes in sympathetic or cardiac baroreflex sensitivity.
    MeSH term(s) Humans ; Female ; Male ; Blood Pressure/physiology ; Multiple Sclerosis, Relapsing-Remitting ; Multiple Sclerosis ; Baroreflex/physiology ; Muscle, Skeletal ; Hypertension ; Heart Rate/physiology
    Language English
    Publishing date 2023-12-28
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 2645330-7
    ISSN 2211-0356 ; 2211-0348
    ISSN (online) 2211-0356
    ISSN 2211-0348
    DOI 10.1016/j.msard.2023.105416
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Age alters the thermoregulatory responses to extreme heat exposure with accompanying activities of daily living.

    McKenna, Zachary J / Foster, Josh / Atkins, Whitley C / Belval, Luke N / Watso, Joseph C / Jarrard, Caitlin P / Orth, Bonnie D / Crandall, Craig G

    Journal of applied physiology (Bethesda, Md. : 1985)

    2023  Volume 135, Issue 2, Page(s) 445–455

    Abstract: Older adults are at greater risk for heat-related morbidity and mortality, due in part to age-related reductions in heat dissipating capabilities. Previous studies investigating the impact of age on responses to heat stress used approaches that lack ... ...

    Abstract Older adults are at greater risk for heat-related morbidity and mortality, due in part to age-related reductions in heat dissipating capabilities. Previous studies investigating the impact of age on responses to heat stress used approaches that lack activities of daily living and therefore may not accurately depict the thermal/physiological strain that would occur during actual heatwaves. We sought to compare the responses of young (18-39 yr) and older (≥65 yr) adults exposed to two extreme heat simulations. Healthy young (
    MeSH term(s) Humans ; Aged ; Activities of Daily Living ; Extreme Heat ; Hot Temperature ; Body Temperature Regulation/physiology ; Sweating ; Body Temperature/physiology
    Language English
    Publishing date 2023-07-06
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, N.I.H., Extramural
    ZDB-ID 219139-8
    ISSN 1522-1601 ; 0021-8987 ; 0161-7567 ; 8750-7587
    ISSN (online) 1522-1601
    ISSN 0021-8987 ; 0161-7567 ; 8750-7587
    DOI 10.1152/japplphysiol.00285.2023
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Low-dose fentanyl reduces pain perception, muscle sympathetic nerve activity responses, and blood pressure responses during the cold pressor test.

    Watso, Joseph C / Huang, Mu / Belval, Luke N / Cimino, Frank A / Jarrard, Caitlin P / Hendrix, Joseph M / Hinojosa-Laborde, Carmen / Crandall, Craig G

    American journal of physiology. Regulatory, integrative and comparative physiology

    2021  Volume 322, Issue 1, Page(s) R64–R76

    Abstract: Our knowledge about how low-dose (analgesic) fentanyl affects autonomic cardiovascular regulation is primarily limited to animal experiments. Notably, it is unknown if low-dose fentanyl influences human autonomic cardiovascular responses during painful ... ...

    Abstract Our knowledge about how low-dose (analgesic) fentanyl affects autonomic cardiovascular regulation is primarily limited to animal experiments. Notably, it is unknown if low-dose fentanyl influences human autonomic cardiovascular responses during painful stimuli in humans. Therefore, we tested the hypothesis that low-dose fentanyl reduces perceived pain and subsequent sympathetic and cardiovascular responses in humans during an experimental noxious stimulus. Twenty-three adults (10 females/13 males; 27 ± 7 yr; 26 ± 3 kg·m
    MeSH term(s) Adult ; Analgesics, Opioid/administration & dosage ; Analgesics, Opioid/adverse effects ; Blood Pressure/drug effects ; Cardiovascular System/innervation ; Cold Temperature ; Cross-Over Studies ; Female ; Fentanyl/administration & dosage ; Fentanyl/adverse effects ; Humans ; Immersion ; Male ; Muscle, Skeletal/innervation ; Pain/drug therapy ; Pain/physiopathology ; Pain/psychology ; Pain Perception/drug effects ; Pain Threshold/drug effects ; Sympathetic Nervous System/drug effects ; Sympathetic Nervous System/physiopathology ; Time Factors ; Water ; Young Adult
    Chemical Substances Analgesics, Opioid ; Water (059QF0KO0R) ; Fentanyl (UF599785JZ)
    Language English
    Publishing date 2021-12-01
    Publishing country United States
    Document type Journal Article ; Randomized Controlled Trial ; Research Support, N.I.H., Extramural
    ZDB-ID 603839-6
    ISSN 1522-1490 ; 0363-6119
    ISSN (online) 1522-1490
    ISSN 0363-6119
    DOI 10.1152/ajpregu.00218.2021
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Influence of ischemia-reperfusion injury on endothelial function in men and women with similar serum estradiol concentrations.

    Lalande, Sophie / Hemingway, Holden W / Jarrard, Caitlin P / Moore, Amy M / Olivencia-Yurvati, Albert H / Richey, Rauchelle E / Romero, Steven A

    American journal of physiology. Regulatory, integrative and comparative physiology

    2021  Volume 321, Issue 2, Page(s) R273–R278

    Abstract: Prior data suggest that, relative to the early follicular phase, women in the late follicular phase are protected against endothelial ischemia-reperfusion (I/R) injury when estradiol concentrations are highest. In addition, endothelial I/R injury is ... ...

    Abstract Prior data suggest that, relative to the early follicular phase, women in the late follicular phase are protected against endothelial ischemia-reperfusion (I/R) injury when estradiol concentrations are highest. In addition, endothelial I/R injury is consistently observed in men with naturally low endogenous estradiol concentrations that are similar to those of women in the early follicular phase. Therefore, the purpose of this study was to determine whether the vasodeleterious effect of I/R injury differs between women in the early follicular phase of the menstrual cycle and age-matched men. We tested the hypothesis that I/R injury would attenuate endothelium-dependent vasodilation to the same extent in women and age-matched men with similar circulating estradiol concentrations. Endothelium-dependent vasodilation was assessed via brachial artery flow-mediated dilation (duplex ultrasound) in young healthy men (
    MeSH term(s) Adult ; Arm/blood supply ; Brachial Artery/diagnostic imaging ; Brachial Artery/physiopathology ; Endothelium, Vascular/physiopathology ; Estradiol/blood ; Female ; Follicular Phase/blood ; Humans ; Male ; Reperfusion Injury/blood ; Reperfusion Injury/diagnostic imaging ; Reperfusion Injury/physiopathology ; Sex Factors ; Vasodilation ; Young Adult
    Chemical Substances Estradiol (4TI98Z838E)
    Language English
    Publishing date 2021-07-14
    Publishing country United States
    Document type Comparative Study ; Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 603839-6
    ISSN 1522-1490 ; 0363-6119
    ISSN (online) 1522-1490
    ISSN 0363-6119
    DOI 10.1152/ajpregu.00147.2021
    Database MEDical Literature Analysis and Retrieval System OnLINE

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