Min Period Research Articles

Endovascular aortic occlusion improves return of spontaneous circulation after longer periods of cardiopulmonary resuscitation: A translational study in pigs

IntroductionResuscitative endovascular balloon occlusion of the aorta (REBOA) has emerged as an adjunct to CPR for nontraumatic cardiac arrest (NTCA). This translational study investigated the impact of varying low-flow duration (15- vs 30-mins) on REBOA's hemodynamic performance and ability to achieve return of spontaneous circulation (ROSC) in a porcine model. MethodsThirty-two pigs were anesthetized and placed into ventricular fibrillation. All animals received a 4-min no-flow period before CPR was initiated. Animals were randomized into four groups: 15- vs 30-minutes of CPR; REBOA vs. no-REBOA. After completion of 15- or 30-minute low-flow, ACLS was initiated and REBOA was inflated in experimental animals. ResultsIn the 15-mins groups, there were no differences in the rates of ROSC between REBOA (4/8, 50%) and control (4/8, 50%; p = 0.99). However, in the 30-min groups, the REBOA animals had a significantly higher rate of ROSC (6/8, 75%) compared to control (1/8, 12.5%; p = 0.04). In the 7-mins after REBOA deployment in the 30-min animals there was a statistically significant difference in coronary perfusion pressure (REBOA 42.1 mmHg, control 3.6 mmHg, p = 0.038). Importantly, 5/6 animals that obtained ROSC in the 30-min group with REBOA re-arrested at least once, with 3/6 maintaining ROSC until study completion. ConclusionIn our porcine model of NTCA, REBOA preferentially improved hemodynamics and ROSC after a 30-mins period of low-flow CPR. REBOA may be a viable strategy to improve ROSC after prolonged downtime, however, more hemodynamic support will be required to maintain ROSC.

Quantification of saccadic fatigability and diagnostic efficacy for myasthenia gravis.

The diagnostic challenge of myasthenia gravis (MG) is exacerbated by the variable efficacy of current testing methodologies, necessitating innovative approaches to accurately identify the condition. This study aimed to assess ocular muscle fatigue in patients with MG using video-oculography (VOG) by examining repetitive saccadic eye movements and comparing these metrics to those of healthy control participants. This prospective, cross-sectional study was conducted at a tertiary care center and involved 62 patients diagnosed with MG (48 with ocular MG and 14 with generalized MG) and a control group of 31 healthy individuals, matched for age and sex. The assessment involved recording saccadic eye movements within a ± 15° range, both horizontally and vertically, at a rate of 15 saccades per minute over a 5-min period, resulting in 75 cycles. Participants were afforded a 3-min rest interval between each set to mitigate cumulative fatigue. The primary outcome was the detection of oculomotor fatigue, assessed through changes in saccadic waveforms, range, peak velocity, latency, and the duration from onset to target, with a focus on comparing the second saccade against the average of the last five saccades. In the evaluation of repetitive saccadic movements, patients with MG exhibited a reduced saccadic range and a prolonged duration to reach the target, compared to healthy subjects. Furthermore, a significant elevation in the frequency of multistep saccades was observed among MG patients, with a marked rise observed over consecutive trials. Receiver operating characteristic (ROC) analysis revealed the discriminative performance of multistep saccade frequency, in conjunction with variations in saccadic range and duration from onset to target achievement between the second saccade and the mean of the final five saccades, as effective in distinguishing MG patients from healthy subjects. Although alterations in peak saccadic velocity and latency were less pronounced, they were nevertheless detectable. The utilization of VOG for repetitive saccadic testing in the diagnosis of MG has demonstrated considerable diagnostic precision. This methodology affords significant accuracy in evaluating ocular muscle fatigue in MG patients, providing class III evidence supportive of its clinical application.

Optimizing resuscitation of the donation after circulatory death heart by mitochondrial protection in a female porcine model.

Due to the shortage of donor organs, an increasing number of transplant organs are harvested after circulatory arrest (donation after circulatory death, DCD). Using a translational porcine DCD model, we developed and evaluated a protocol based on cardioprotection by multi-drug postconditioning to optimize resuscitation of DCD hearts by ex situ heart perfusion (ESHP). Hearts of female pigs (45.0±4.5 kg) were procured following a clinically identical DCD protocol, consisting of the termination of ventilator support and confirmation of circulatory arrest, followed by a 15-min standoff period. DCD hearts were randomly allocated to ESHP (38.4°C) in the absence (untreated, N=5) or presence (treated, N=5) of a postconditioning treatment added to the perfusate, consisting of Intralipid (1%), sevoflurane (2% v/v), and remifentanil (3 nM). All hearts were perfused with blood and Krebs-Henseleit solution (1:1) for 60 min in Langendorff mode and for additional 300 min in working mode for a total perfusion time of 6 hrs. Oxidative capacity and detailed left ventricular (LV) mechanical function under increasing workload (left atrial pressure 6-12 mmHg) were assessed hourly. LV tissue was snap-frozen at the end of ESHP and used for molecular analyses. LV inotropy (LVdP/dtmax) did not decline over time in treated DCD hearts and was significantly higher at the end of the protocol as compared with untreated DCD hearts (ΔLVdP/dtmax= 440 mmHg/s, p=0.009). Treated DCD hearts exhibited persistently higher LV stroke work index (LVSWI) during the 6-hr period of ESHP, whereas untreated DCD hearts displayed a significant decline (ΔLVSWI=-3.10 mL*mmHg/g, p(time within untreated group)<0.001). Treated DCD hearts displayed higher metabolic activity as measured by oxygen consumption (ΔO2=3.11 mL O2/min/100g; p=0.004), and released lower amounts of cell-free mitochondrial DNA into the perfusate, a marker of potential graft dysfunction. Treated hearts also used fatty acids from Intralipid as an energy source, while untreated DCD hearts showed glyceroneogenesis with triglyceride accumulation and depletion of tricarboxylic acid cycle intermediates, reduced mitochondrial complex I, II, and III activities with accumulation of mitochondrial NADH, and signs of ultrastructural damage. A translationally relevant protective ESHP protocol consisting of treatment with Intralipid, sevoflurane, and remifentanil markedly accelerated functional recovery and improved viability of DCD hearts.

Cold atmospheric plasma enhances morphological and biochemical attributes of tomato seedlings

Cold atmospheric plasma (CAP) is a physical technology with notable effects on living organisms. In the present study, tomato seeds (Solanum lycopersicum var. Bassimo Mill.) were exposed to CAP for various time intervals, ranging from 1 to 5 min, in both continuous and intermittent periods, and were compared with a control group that received no CAP treatment. Seedlings grown from treated seeds exhibited improvements in levels of growth traits, photosynthetic pigments, and metabolite contents when compared to the control group. Seedlings from seeds treated with S04 displayed significant increases in shoot and root lengths, by 32.45% and 20.60% respectively, compared to the control group. Moreover, seedlings from seeds treated with S01 showed a 101.90% increase in total protein, whereas those treated with S02 experienced a 119.52% increase in carbohydrate content. These findings highlight the substantial improvements in growth characteristics, photosynthetic pigments, and metabolite levels in seedlings from treated seeds relative to controls. Total antioxidant capacity was boosted by CAP exposure. The activities of enzymes including superoxide dismutase, catalase, and peroxidases were stimulated by S02 and exceeded control treatment by (177.48%, 137.41%, and 103.32%), respectively. Additionally, exposure to S04 increased the levels of non-enzymatic antioxidants like flavonoids, phenolics, saponins, and tannins over the control group (38.08%, 30.10%, 117.19%, and 94.44%), respectively. Our results indicate that CAP-seed priming is an innovative and cost-effective approach to enhance the growth, bioactive components, and yield of tomato seedlings.

Non-Invasive Monitoring of Microvascular Oxygenation and Reactive Hyperemia using Hybrid, Near-Infrared Diffuse Optical Spectroscopy for Critical Care.

The detection of levels of impairment in microvascular oxygen consumption and reactive hyperemia is vital in critical care. However, there are no practical means for a robust and quantitative evaluation. This paper describes a protocol to evaluate these impairments using a hybrid near-infrared diffuse optical device. The device contains modules for near-infrared time-resolved and diffuse correlation spectroscopies and pulse-oximetry. These modules allow the non-invasive, continuous, and real-time measurement of the absolute, microvascular blood/tissue oxygen saturation (StO2) and the blood flow index (BFI) along with the peripheral arterial oxygen saturation (SpO2). This device uses an integrated, computer-controlled tourniquet system to execute a standardized protocol with optical data acquisition from the brachioradialis muscle. The standardized vascular occlusion test (VOT) takes care of the variations in the occlusion duration and pressure reported in the literature, while the automation minimizes inter-operator differences. The protocol we describe focuses on a 3-min occlusion period but the details described in this paper can readily be adapted to other durations and cuff pressures, as well as other muscles. The inclusion of an extended baseline and post-occlusion recovery period measurement allows the quantification of the baseline values for all the parameters and the blood/tissue deoxygenation rate that corresponds to the metabolic rate of oxygen consumption. Once the cuff is released, we characterize the tissue reoxygenation rate, magnitude, and duration of the hyperemic response in BFI and StO2. These latter parameters correspond to the quantification of the reactive hyperemia, which provides information about the endothelial function. Furthermore, the above-mentioned measurements of the absolute concentration of oxygenated and deoxygenated hemoglobin, BFI, the derived metabolic rate of oxygen consumption, StO2, and SpO2 provide a yet-to-be-explored rich data set that can exhibit disease severity, personalized therapeutics, and management interventions.

Low-dose short infusion ketamine as adjunct to morphine for acute long bone fracture in the emergency department: a randomized controlled trial

BackgroundKetamine is recognized as an alternative for pain management; however, concerns about emergent adverse reactions have limited its widespread adoption. This study aimed to assess the efficacy of a short infusion of low-dose ketamine (LDK) compared to intravenous morphine (MOR) as adjunctive analgesia for acute long bone fracture pain.MethodsThis single-blinded, randomized controlled trial was conducted in a single emergency department. Patients with acute long bone fractures and numerical rating scale (NRS) pain scores ≥ 6 following an initial dose of intravenous morphine were assigned to receive either a LDK (0.3 mg/kg) over 15 min or intravenous MOR at a dose of 0.1 mg/kg administered over 5 min. Throughout a 120-min observation period, patients were regularly evaluated for pain level (0–10), side effects, and the need for additional rescue analgesia.ResultsA total of 58 subjects participated, with 27 in the MOR group and 31 in the LDK group. Demographic variables and baseline NRS scores were comparable between the MOR (8.3 ± 1.3) and LDK (8.9 ± 1.2) groups. At 30 min, the LDK group showed a significantly greater mean reduction in NRS scores (3.1 ± 2.03) compared to the MOR group (1.8 ± 1.59) (p = 0.009). Similarly, at 60 min, there were significant differences in mean NRS score reductions (LDK 3.5 ± 2.17; MOR mean reduction = 2.4, ± 1.84) with a p-value of 0.04. No significant differences were observed at other time intervals. The incidence of dizziness was higher in the LDK group at 19.4% (p = 0.026).ConclusionShort infusion low-dose ketamine, as an adjunct to morphine, is effective in reducing pain during the initial 30 to 60 min and demonstrated comparability to intravenous morphine alone in reducing pain over the subsequent 60 min for acute long bone fractures. However, it was associated with a higher incidence of dizziness.Trial registrationNMRR17318438970 (2 May 2018;www.nmrr.gov.my).

Emissions and exposure to NOx, CO, CO2 and PM2.5 from a gas stove using reference and low-cost sensors

Gas stoves and cooking are significant sources of indoor pollution. Using a combination of regulatory and calibrated low-cost sensors (LCS) we measured NO, NO2, CO and CO2 emission rates (g hr−1) and emission factors (g J−1) from a natural-gas stove and oven. The emission rates for gaseous pollutants were significantly higher, by factors of 2.6–29, from the oven compared to the stove for every pollutant measured.To evaluate the indoor air concentrations, we used a calibrated low-cost sensor (TSI Inc, AirAssure) to examine indoor concentration of CO, CO2, NO2 and PM2.5 for one month in one U.S. home with a gas stove during normal activities, including cooking. Indoor concentrations of one or more pollutants exceeded the U.S. EPA's Air Quality Index (AQI) level of 100 (for CO, NO2, and PM2.5) or 2000 ppm (for CO2) for an average of 99 min per day. The AirAssure, with only the manufacturer's calibration, was an excellent indicator of times when indoor concentrations of CO, CO2, and NO2 exceeded these reference levels. Without in-situ calibration, the AirAssure underestimated in-home PM2.5 concentrations. After in-situ calibration, the AirAssure correctly identified 1-min periods when the AQI was >100 85% of the time (up from 46% of the time without calibration).

Three-dimensional crosslinked structure assembled by novel elemental iodine doped Nb2O5 ultrathin nanosheets for exceptional visible-light photocatalytic performance

The application of Nb2O5 in photocatalysis has sparked interest due to its potent oxidation capabilities and eco-friendly properties. However, challenges such as poor visible light response, limited reactive active sites and rapid charge recombination still hinder its practical use. Herein, a novel approach introduces elemental I-doped Nb2O5 (INO) catalyst with a three-dimensional crosslinked structure formed by ultrathin nanosheets, for the first time. This pioneering approach results in the INO catalyst with a high specific surface area (98.51 m2 g−1), abundant active sites, and enhanced visible light absorption. The dispersion of elemental I within the Nb2O5 lattice promotes the presence of delocalized electrons and improves charge carrier mobility, leading to superior catalytic performance for the degradation of diclofenac (DCF). During a 75-min period, the degradation efficiency of INO catalyst to diclofenac was found to reach 91.5 %, with a corresponding rate constant of 35.0 × 10−3 min−1. Furthermore, the study investigates the DCF degradation pathway and the toxicity changes in its byproducts. This innovative research opens new avenues for enhancing the visible light catalytic activity of Nb2O5 catalysts.

Impact of Peripheral Versus Central Insulin on Cerebrovascular Compliance in Healthy Young Adults

Objective: Vascular compliance is an essential component of cerebral blood flow regulation. Prior work has shown cerebral vasodilation (elicited by hypercapnia) reduces cerebrovascular compliance (Ci); however, this work has yet to be translated to other vasoactive compounds. Insulin has important vasodilatory effects in the peripheral circulation, but less is known about the role of insulin in cerebrovascular control. Herein, we hypothesized both peripheral (intravenous) and central (intranasal) insulin administration would increase indices of cerebral blood flow and reduce Ci in healthy young adults. Methods: Twenty-five healthy young adults (8 female; 26±7 yrs, 25±3 kg/m2) were assigned to two separate protocols (NCT05244694, NCT05153395). Middle cerebral artery blood velocity (MCAv, transcranial Doppler ultrasound) was measured at baseline and under two study conditions: 1) at the end of a 60 min hyperinsulinemic euglycemic infusion, and 2) 60 min following 160 IU of intranasal insulin. Indices of Ci were calculated using a modified Windkessel model applied to blood pressure (finger photoplethysmography) and corresponding MCAv waveforms collected over a 5-min period (10 waveforms) at baseline and during the aforementioned insulin conditions. Results: Blood glucose remained unchanged throughout both protocols (both p&gt;0.05). MCAv was maintained over time under both insulin conditions (protocol 1: 60±13 to 62±17 cm/s, p=0.635; protocol 2: 58±9 to 53±14 cm/s, p=0.146). In contrast, Ci decreased (0.00028±0.00010 to 0.00021±0.00007 cm/s/mmHg, p=0.010) from baseline during peripheral (intravenous) insulin administration. No change in Ci (0.00049±0.00025 to 0.00040±0.00018 cm/s/mmHg, p=0.189) were observed following intranasal insulin administration. Conclusions: Contrary to our hypothesis, there was no effect of peripheral or central insulin administration on resting MCAv in healthy young adults. However, intravenous (but not intranasal) insulin reduced Ci by approximately 25% from baseline values. These findings advance our understanding of cerebrovascular control mechanisms during insulin exposure and provide the opportunity to extend this work to diseased states characterized by insulin resistance, including diabetes. CAFNR Joy of Discovery (JKL, JP). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Vascular responses during handgrip exercise in healthy postmenopausal females and older males

Introduction: Aerobic exercise interventions improve peripheral endothelial function in healthy older males. However, this effect is not always observed in healthy postmenopausal females and possible mechanisms underlying this sex-related difference remain unknown. Greater vascular shear stress during acute exercise is a key stimulus mediating longer-term improvements in vascular function. It remains unknown if postmenopausal females display a reduced endothelial sensitivity to exercise-induced shear stress relative to males of similar age. Objective and hypothesis: The objective of this study is to test the hypothesis that healthy postmenopausal females exhibit a lower endothelial sensitivity to exercise-induced shear stress relative to males. Methods: Fourteen healthy postmenopausal females (67 ± 8 years) not under hormone replacement therapy and 9 males of similar age (65 ± 7 years) performed handgrip exercise for 4 minutes at 20%, 40%, 60%, and 80% of their maximal voluntary contraction. Each exercise bout was separated by a 10-min recovery period. Brachial artery diameter and blood velocity were continuously measured using high-resolution ultrasound and analyzed using edge-detection software. Endothelial sensitivity to shear rate was quantified as the slope of the linear regression between brachial artery dilation (% change from baseline) and shear stress and compared between groups with an independent t-test. Workload, vascular conductance, diameter dilation, and shear stress were analyzed with mixed-effects models. Results: Males exercised at greater workloads relative to females across all exercise bouts (M: 17 ± 11 vs. F: 9 ± 5 kg, p&lt;0.01). Forearm vascular conductance was greater in males throughout each exercise intensity (M: 2.23 ± 1.70 vs. F: 1.03 ± 0.51 ml/min/mmHg, p=0.02). Despite these differences, arterial dilation (M: 5.32 ± 5.55 vs. F: 5.20 ± 4.80%, p=0.96) and shear stress (M: 142 ± 80 vs. F: 171 ± 86 s−1, p=0.27) did not differ between groups across exercise intensities. Endothelial sensitivity to exercise-induced shear stress did not differ between males (0.02 ± 0.05%/s−1) and females (0.03 ± 0.01%/s−1, p=0.67). Conclusion: These data suggest that a reduced endothelial sensitivity to exercise-induced shear stress may not explain why aerobic exercise interventions do not consistently improve peripheral endothelial function in healthy postmenopausal females. Montreal Heart Institute Foundation. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Older versus Younger Females Matched for Body Composition Have Lower Sympathetic Transduction at Rest

BACKGROUND: Older female (OF) adults have the highest risk for hypertension and cardiovascular disease among any demographic in America. Therefore, there is a need to better understand the contributors to impaired blood pressure (BP) regulation in female aging. Bursts of spontaneously occurring muscle sympathetic nerve activity (MSNA) contribute to BP regulation on a beat-to-beat basis (i.e., sympathetic transduction). Previous work suggests that OF have attenuated resting sympathetic transduction but there is a need for additional work considering covariates that affect sympathetic transduction (e.g., body mass index (BMI) &amp; sodium intake). We tested the hypothesis that aging attenuates sympathetic transduction in OF (&gt;55 years) compared with young female (YF; 18-35 years) participants matched for body composition and pre-trial sodium intake. METHODS: We studied seven post-menopausal OF (65±6 years) and nine YF (24±4 years; tested in early follicular phase) participants with seated brachial BP &lt;140/90 mmHg after three days of specified sodium intake (target 2300mg/day). We measured mean BP (photoplethysmography) and MSNA (microneurography) during a 10-min rest period in the supine position. We also assessed BMI, body fat % (BF%; bioelectrical impedance), and habitual moderate-to-vigorous physical activity (MVPA) during ≥7 consecutive days using waist-worn accelerometers (ActiGraph). We compared the average change in BP for 10 cardiac cycles after an MSNA burst (i.e., signal-averaged sympathetic transduction) using mixed-effects models (group*time[repeated measure]). We compared other variables using unpaired, two-tailed t-tests for normally distributed data and Mann-Whitney U tests for non-normally distributed data (i.e., failed Shapiro-Wilk test). We compared sodium intake, BMI, BF% and MVPA using equivalence testing. Significance was set to α&lt;0.05. RESULTS: Sodium intake, BMI, BF% and MVPA were equivalent between groups (p&gt;0.06). The following data are presented as OF vs. YF with mean ± SD or median[IQR]. Mean BP (97[22] vs. 77[5] mmHg, p=0.008) and MSNA burst frequency (35±6 vs. 13±4 bursts/min, p&lt;0.0001) were higher in OF. OF had lower mean BP changes following MSNA bursts (time: p&lt;0.0001, group: p=0.013, interaction: p=0.026) with pairwise differences among cardiac cycles 4-10 (post hoc p-values: p≤0.012). Moreover, peak increases in mean BP following MSNA bursts were lower in OF (Δ1.9±0.4 vs. 4.9±2.2 mmHg, p=0.003). CONCLUSION: We found that OF have attenuated sympathetic transduction to BP when compared to YF matched for body composition and sodium intake. This extends past work suggesting that female aging is associated with attenuated sympathetic transduction to BP. National Institutes of Health K01HL160772 (JCW), American Heart Association 23CDA1037938 (JCW), &amp; Florida State University Graduate School Legacy Fellowship, 2023 (CD). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Pulsatile Perfusion Therapy at 0.1 Hz Improves Survival Following Severe Hemorrhage in Rats

Oscillations in arterial pressure and blood flow at 0.1 Hz are associated with protection of tissue oxygenation during conditions of reduced tissue perfusion. Pulsatile Perfusion Therapy (PPT) is a method we have developed to induce these oscillations, and has been associated with increased tolerance to simulated hemorrhage via lower body negative pressure in humans. However, it is unknown how effective this therapy would be in an actual hemorrhage model. The aim for this study was to test the effcacy of PPT in a rat model of severe hemorrhage. We hypothesized that PPT at 0.1 Hz would protect arterial pressure and cerebral blood flow following severe hemorrhage in rats, subsequently improving survival. Eleven adult Sprague-Dawley rats (six female, five male) were anesthetized via isoflurane, then underwent bilateral carotid artery catheterization for assessment of arterial pressure and carotid artery blood flow, while heart rate was assessed via lead II ECG. Following a 15-min baseline period, all animals were hemorrhaged to 50% of their estimated blood volume over 30-min. Rats were then randomly assigned to the PPT group (3 female, 3 male) or the control group (CON; 3 female, 2 male). PPT was administered via inflatable cuffs attached to both hind limbs, oscillating between 0 mmHg and 250 mmHg every 5-s (10-s cycles or 0.1 Hz) for 30-min immediately following hemorrhage. For the CON group, the leg cuffs were also attached but were not inflated for this 30-min period. All animals were then monitored for an additional 150-min recovery period post-hemorrhage, or until death — defined as the absence of ventricular function on the ECG. Survival time and peak mean arterial pressure (MAP), carotid blood flow, and heart rate were assessed to determine the effectiveness of PPT in protecting hemodynamic responses following hemorrhage. PPT increased survival time ( P = 0.02), with 3 of 6 (50%) rats in the PPT group and 0 of 5 (0%) rats in the CON group surviving the entire 180-min recovery period following hemorrhage. During recovery, PPT protected MAP (PPT: −46.5 ± 12.9% vs. CON: −72.6 ± 19.5% from baseline; P = 0.07) and carotid blood flow (PPT: −61.5 ± 17.7% vs. CON: −83.7 ± 6.7% from baseline; P = 0.04), but did not affect heart rate (PPT: 0.11 ± 6.58% vs. CON: −18.70 ± 29.34% from baseline, P = 0.20), although responses were highly variable between subjects. PPT protected arterial pressure and carotid blood flow in rats following severe hemorrhage, subsequently improving survival. These data add further evidence for the use of 0.1 Hz hemodynamic oscillations as a therapeutic intervention for the treatment of hemorrhage. Physiology and Anatomy Department Seed Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Effect of 0.1 Hz Blood Flow Oscillations on Microvascular Blood Flow Responses Following Severe Ischemia

Background: We have shown that inducing 10 second (0.1 Hz) oscillations in arterial pressure and blood flow protects against reductions in tissue oxygenation during ischemia, independent of changes in macrovascular blood flow. However, it is unknown whether 0.1 Hz hemodynamic oscillations impacts microvascular function and vasodilatory capacity following severe ischemia. To examine this question, we assessed the reactive hyperemic response following a prolonged peripheral limb ischemia protocol with and without induced 0.1 Hz hemodynamic oscillations. Hypothesis: 0.1 Hz oscillations in blood pressure and blood flow will increase microvascular blood flow, assessed via reactive hyperemia following a 10-min period of ischemia. Methods: Thirteen healthy human participants (6M, 7F; 27.3 ± 4.2 y) completed two experimental protocols separated by ≥48 h. In both conditions, ischemia of the forearm was induced with a pneumatic cuff on the upper arm to decrease brachial artery blood velocity by ~70-80% from baseline. In the oscillation condition (OSC), 0.1 Hz oscillations in mean arterial pressure (MAP) and brachial artery blood flow were induced by inflating and deflating bilateral thigh cuffs every 5-s (10-s cycles; 0.1 Hz) throughout the forearm ischemia period. In the control condition (CON), the thigh cuffs were in place, but were inactive throughout the forearm ischemia period. Beat to beat arterial pressure was measured via finger photo plethysmography, and brachial artery diameter and blood velocity were measured via duplex Doppler ultrasound during baseline, ischemia, and the reperfusion period. The maximum mean brachial artery blood velocity, and 3-min area under the curve (AUC) of mean brachial artery blood velocity were used to determine the reactive hyperemia response. Results: The magnitude of forearm ischemia, indexed by the reduction in brachial artery conductance, was matched between conditions (CON: -74.8 ± 10.4% vs. OSC: -75.6 ± 6.7%, p=0.39). Reactive hyperemia was not different between conditions as indexed by maximum mean brachial artery blood velocity (CON: 36.4 ± 12.4 cm/s vs. OSC: 39.3 ± 11.2 cm/s, p=0.53) or 3-min brachial artery blood velocity AUC (CON: 1495 ± 744 (cm/s)2 vs. OSC: 1596 ± 804 (cm/s)2, p=0.74). Conclusion: Inducing 0.1 Hz hemodynamic oscillations during severe ischemia does not affect microvascular function, indexed by reactive hyperemia following release of the ischemic stimulus. A more direct measure of microvascular blood flow is needed to examine whether 0.1 Hz hemodynamic oscillations improves microvascular perfusion during ischemia. NIH Neurobiology of Aging &amp; Alzheimer’s Disease Training Grant (T32 AG02049; KAD); American Heart Association Transformational Project Award (19TPA34910743; CAR); American Heart Association Predoctoral Fellowship (23PRE1018469; KAD); UNTHSC Physiology and Anatomy Seed Grant 2021 (CAR). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Dual role of ‘Al’ impregnated porous MCM-41/ZSM5 composites for the production of biohydrogen and green liquid hydrocarbons

Bio alternative fuels is the most researched concept which is due to the exhausting fossils and aggregating pollutants. Fuels of liquid and gaseous types are much in demand due to the high expectations from liquid and gas dependent engines. This report is the first of its kind to establish the effectiveness of the synthesized synergistic composite material of micro and mesoporosity for the production of biohydrogen and bioliquid organics from kitchen waste. Optimization of temperature, feed:catalyst ratio, and time of study were studied using AlMCM-41 and the efficient yield of products was obtained at 400 0C, 0.5g of catalyst and at 40min period. Composites were synthesized with AlMCM-41 and ZSM-5 zeolite in core-shell manner. Composite AlMCM-41/ZSM-5 yielded the highest of 70% GLF and maximum of 26.5% of H2. The synthesized materials were characterized using XRD, BET, N2 sorption studies, TPD, SEM and TEM. The synergism was well established and also the catalysts showed remarkable reproducibility.

Pharmacological Targeting of Endothelial KCa Channels In Vivo Augments Vasodilatory Responses in Rat Femoral and Coronary Arteries in Health and Disease

As the primary interface between the blood and organs, the vascular endothelium functions as a key regulator of tissue blood flow by sensing chemical and mechanical stimuli and producing vasoactive signals to dynamically control intraluminal diameter in local arterioles and upstream arteries. Flow-mediated dilation (FMD) is an important physiological mechanism to modify local tissue perfusion in response to dynamic metabolic conditions, and reduced FMD responses are indicative of endothelial dysfunction, the latter being a major risk factor for cardiovascular disease. We have previously reported that pharmacological enhancement of endothelial KCa2.3 and KCa3.1 channel activity by SKA-31 augmented vasodilatory responses in small resistance arteries and intact hearts isolated from healthy and Type 2 Diabetic (T2D) rats (RC Mishra et al, 2014, 2021). In the present study, we have investigated the ability of SKA-31 to enhance endothelium-dependent vasodilation in vivo in femoral and coronary arteries of healthy and T2D male rats. Methods: FMD responses associated with reactive hyperemia were measured in a side branch of the femoral artery by high sensitivity Doppler ultrasound following release of an inflated pressure cuff placed on the distal hind limb of male Sprague Dawley (SD) and T2D Goto-Kakizaki (GK) rats (26-32 weeks of age). Rats were injected i.p. with either 10 mg/kg SKA-31 or drug vehicle ~ 3 hours prior to cuff inflation. M-mode echocardiographic imaging was used to visualize intraluminal diameter changes in the left main coronary artery in the same four treatment groups in response to an increase in inhalational isoflurane from 2% to 5%. Results: Femoral artery blood flow increased ~2-fold during reactive hyperemia in vehicle treated SD rats, as quantified by velocity-time integral, and did not increase further with SKA-31 treatment. In contrast, the FMD response in vehicle treated T2D GK rats was substantially blunted vs. SD rats, and SKA-31 administration restored this response to the level observed in healthy controls, which was still observable 15-24 hours later. In vehicle treated SD rats, exposure to 5% isoflurane increased left main coronary arterial diameter by 50-60%, which reversed to baseline following return to the original 2% isoflurane condition. SKA-31 treatment of SD rats increased basal arterial diameter by ~30%, but did not significantly modify the observed increase in arterial diameter evoked by 5% isoflurane inhalation, compared with vehicle treatment. In vehicle treated T2D GK rats, exposure to 5% isoflurane did not increase coronary artery diameter over a 10 min period, which is suggestive of endothelial dysfunction. However, SKA-31 treatment significantly increased basal coronary arterial diameter by 40-50%, and promoted a rapid and robust increase in diameter following exposure to 5% isoflurane (80-90% increase above that observed in vehicle treated T2D rats), which reversed to baseline upon return to 2% isoflurane inhalation. No enhancement of isoflurane evoked coronary vasodilation was observable in T2D GK rats 15-24 hrs post-SKA-31 treatment. In summary, these data provide the first direct demonstration that low dose administration of a KCa channel activator can enhance vasodilatory responses in vivo. This study was supported by research funding to APB from the Canadian Institutes of Health Research (MOP-142467) and NSERC (RGPIN 2017-04116). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Intraperitoneally injected d11-11(12)-epoxyeicosatrienoic acid is rapidly incorporated and esterified within rat plasma and peripheral tissues but not the brain

Epoxyeicosatrienoic acids (EpETrEs) are bioactive lipid mediators of arachidonic acid cytochrome P450 oxidation. In vivo, the free (unbound) form of EpETrEs regulate multiple processes, including blood flow, angiogenesis and inflammation resolution. Free EpETrEs are thought to rapidly degrade via soluble epoxide hydrolase (sEH), yet, in many tissues the majority of EpETrEs are esterified to complex lipids (e.g. phospholipids) suggesting that esterification may play a more dominant role in regulating free, bioactive EpETrE levels. This hypothesis was tested by quantifying the metabolism of intraperitoneally injected free d11-11(12)-Epoxyeicosatrienoic acid (d11-11(12)-EpETrE) in male and female rats. Plasma and tissues (liver, adipose and brain) were obtained 3 to 4 minutes later and assayed for d11-11(12)-EpETrE and its sEH metabolite, d11-11,12-dihydroxyeicosatrienoic acid (d11-11,12-diHETrE) in both the free and esterified lipid fractions. In both males and females, the majority of injected tracer was recovered in liver followed by plasma and adipose. No tracer was detected in the brain, indicating that brain levels are maintained by endogenous synthesis from precursor fatty acids. In plasma, liver, and adipose, the majority (>54%) of d11-11(12)-EpETrE was found esterified to phospholipids and neutral lipids (triglycerides and cholesteryl esters). sEH-derived d11-11,12-diHETrE was not detected in plasma or tissues, suggesting negligible conversion within the 3-4 min period post tracer injection. This study shows that esterification is the main pathway regulating free 11(12)-EpETrE levels in vivo.

Observations of airflow around a supertall curved building and its impact on temperature and humidity in Houston’s urban center

Characterization of realistically shaped skyscrapers embedded in non-uniform neighbourhoods experiencing intricate weather patterns remains inadequately investigated. Aiming to close this gap, the Center for Multiscale Applied Sensing team deployed its mobile observatory in the street canyons around the curved Wells Fargo Plaza skyscraper in downtown Houston, TX. Three deployments allowed airflow observations under different inflow wind and thermodynamic stability conditions. Doppler lidar measurements reveal that when inflow hits the curved wall of the skyscraper, perpendicular canyons experience similar vortex configurations creating two windward and two leeward circulations. Windsond measurements support that buoyancy within the deep street canyons can generate thermal updrafts as strong as 2 m s-1 which is sufficient to overturn the mechanical downwash under gentle wind conditions. Canyons experiencing venting during the daytime were observed to be more thermodynamically stable at night while thermodynamically stable canyons during the day were observed to be more thermodynamically unstable at night owing to the accumulation of heat near street-level. Fourier decomposition of the vertical velocity measurements shows that in all cases flow exhibited high Reynolds numbers and was composed of turbulent eddies of predominantly 6 and 15 min periods. This observational dataset provides insights to assess wind load, pedestrian comfort, urban air mobility, and natural ventilation and may be used as a benchmark for numerical model and wind tunnel studies attempting to represent realistically complex urban conditions.

Cardiovascular Autonomic Control During Hibernation in American Black Bears

The dramatic early decrease in HR upon entry into torpor in small hibernators has recently been shown to be associated with a marked increase in cardiac parasympathetic activity as indicated by increased short term beat to beat heart rate variability (RMSSD) normalized to average R-R interval (RMDSSD/RR, Zanetti et al 2023). At steady state torpor, as their body temperature drop to ~2°C, small hibernators benefit from the Q10 effect on cardiac pacemaker cells in maintaining a low HR with a reduced parasympathetic activity. Black bears in hibernation maintain body temperatures between 30-35°C while suppressing metabolism by 75% and with a marked decrease in HR from non-hibernating 55 bpm to hibernating 6-12 bpm including extreme respiratory sinus arrhythmia (Tøien et al 2011). As hibernating bears would not significantly benefit from the Q10 effect on cardiac pacemaker cells to sustain a low HR, we hypothesized that an elevated cardiac parasympathetic tone is needed to suppress HR. Continuous electrocardiogram (ECG) and blood pressure (BP) were recorded with implantable telemetry transmitters (DSI D70-CCP/EET and Konigsberg T28F-14B) in American black bears. A Pan-Tomkins algorithm modified for R-wave detection with long R-R intervals followed by visual inspection was used for the analysis. RMDSSD/RR for a 2 hour period in mid hibernation with no activity was 3 times higher than that during the resting phase in non-hibernation (0.68 vs. 0.23, n=10 and 7 respectively, p&lt;0.001), confirming the presence of a high parasympathetic tone during hibernation. HR decreased from 68.3 ± 5.8 bpm to 12.9 ± 0.9 bpm (±SE, p&lt;0.0001). RMSSD/RR during a 10 min period recovering from anesthesia (Telazol with supplemental Ketamin) during hibernation in mid March was only 0.019 ± 0.008 vs 0.58 ± 0.14 during a 10 min period before disturbance to induce anesthesia and HR 87.0 ± 8.7 b/min vs. 16.3 ± 1.4 b/min, demonstrating a parasympatholytic effect (n=6, p&lt; 0.0006). The longest R-R intervals during extreme sinus arrhythmia detected in mid hibernation ranged from 11.8 to 33.0 s (Mean 19.0 ± 2.7, n=21). BP typically increased to above 200 mmHg during periods of rapid heart beats, and decayed slowly to 50-60 mmHg at the end of the longest R-R intervals. Analysis of data from a single bear from 2 hour periods at 2 week intervals throughout hibernation and recovery indicates that a high parasympathetic activity is maintained throughout hibernation and strongly correlated to the maximum observed R-R interval. We conclude that opposed to small hibernators, hibernating bears sustain low HR in hibernation with high parasympathetic activity controlling the extreme sinus arrhythmia. We suggest that BP is maintained during long R-R intervals by peripheral vasoconstriction. Supported by NIH COBRE grant number [P20GM130443]. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Neither Aerobic Interval nor Circuit Resistance Exercise Acutely Enhance Glucose Tolerance in Healthy, Young Adults

Physical activity and glycemic control are important factors in preventing chronic disease such as Type II diabetes. Glycemic control may be enhanced during recovery from acute exercise.OBJECTIVES To test the effects of resistance exercise (RT) vs. aerobic interval exercise (AER) on post-exercise blood glucose (BG) control during an oral glucose tolerance test (OGTT).METHODS Ten volunteers completed three separate trials (counter-balanced order): a resting control trial (CON) consisting of a 75-min OGTT following consumption of a 25% glucose solution dosed at 1 g/kg body mass; a RT trial in which subjects completed a 30-min circuit protocol (6-7 sets) of 6 reps/set using 10-RM load for squat, bench press, knee extension and biceps curl; and the AER trial where subjects alternated between treadmill exercise (3 min) and arm crank ergometry (2-min) over a 30-min period (intensity target of 15 on the Borg 6-20 point Rating of Perceived Exertion scale). Both exercise trials were followed by the same 75-min OGTT. BG was assessed via fingertip sampling prior to exercise, mid-exercise, post-exercise, and every 15-min during the OGTT. Blood lactate was collected at rest, mid-exercise, post-exercise and at 15 min of the OGTT.RESULTS Both exercise trials elicited significantly increased lactate but were not different from one another. BG was significantly elevated during the OGTT for all conditions but was not different by condition. BG area under the curve (AUC) was 5.6% smaller (p&gt;0.05) following RT and AER vs. CON (CON: 10687±381; RT: 10087±343; AER: 10093±299 arbitrary units).CONCLUSIONS Acute resistance and aerobic interval exercise were not found to elicit significantly enhanced post-exercise glycemic control. Post-exercise glycemic control may be related to the total energy deficit achieved in young, healthy adults.

Reactive Oxygen Species and Salicylic Acid Mediate the Responses of Pear to Venturia nashicola Infection

Reactive oxygen species (ROS) and salicylic acid (SA) are essential signaling molecules in plant cells that participate in responses to biotic and abiotic stresses. Changes in ROS and SA signals during interactions between pear and the pear scab pathogen Venturia nashicola remain unclear. Herein, we analyzed the roles of ROS in the signal transduction pathway of pear scab resistance using the highly resistant Huangguan and susceptible Xuehua cultivars of pear (Pyrus bretschneideri Rehd). Protoplasts, calluses, and leaves were obtained from 14-year-old pear trees and treated with V. nashicola for different periods. The results showed that ROS rapidly accumulated in protoplasts of both cultivars within a 120-min treatment period, but the fluorescence intensity of ROS differed between cultivars. The H2O2 content in fruit-derived calluses of Huangguan peaked at 48 h post-infection at levels 1.85 times higher than those in Xuehua. Induction of H2O2 by V. nashicola in Huangguan was more intense than in Xuehua over a 96-h treatment period. At 96 h post-infection, the malondialdehyde content in leaves of Huangguan was significantly lower than in Xuehua, while the activities of superoxide dismutase, peroxidase, and catalase, and the relative expression levels of PbMnSOD, PbPOD, and PbCAT genes were higher in Huangguan than Xuehua. V. nashicola infection also caused a continuous increase in the leaf SA content of Huangguan, which was 6.76 times higher than in Xuehua at 96 h post-infection, and V. nashicola exposure upregulated the expression of PbPAL, PbICS, PbPR1, and PbPR5. In summary, both ROS and SA participated in the responses of pear trees to V. nashicola infection and played vital roles in the signal transduction pathway of pear scab resistance.