bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Curriculum Analysis for Preclinical Medical Education: Between Cohorts and Between Instructors
Authors: Anderson Lisa , Shaw Aubie , Levine Erica , Nordgren Kendra
Published: May 2024

Prior to Fall 2023, the two medical campuses of the University of Minnesota, have hadtwo different curricula. Though the Duluth campus has delivered an integrative, systems-based curriculum, the Twin Cities campus has delivered a discipline-basedcurriculum. Outcome measures (1) pass rate and scores on Step 1 board exams, 2)graduation data and 3) match success) demonstrate strong comparability betweenthe two curricula. Starting in September 2020, another opportunity for comparisonoccurred; a single instructor taught pulmonary content to both the Duluth (Fall 2020)and Twin Cities (Spring 2020) cohorts and another single instructor taughtcardiovascular content to both the Duluth (Fall 2020) and Twin Cities (Spring 2021)cohorts. Both cohorts were given and assessed on the same set of learning objectives;leading us to ask the following question: Does the structure of the preclinical curriculum(systems vs discipline-based) impact the learning outcomes of physiology, particularlythe ability to integrate material? We compared the two cohorts by comparing acommon set of exam questions assessing cardiovascular and pulmonary physiology. Wemeasured question performance by question diffculty index (expressed as a percent)and question cognitive level by determining the Bloom’s Taxonomy Cognitive level(knowledge, comprehension, application, analysis, synthesis and evaluation). We foundno differences between the cohorts in question diffculty as a function of content typeor levels of Bloom’s taxonomy. We conclude that there was no difference in overallperformance of the Duluth and Twin Cities cohorts despite receiving different curricularapproaches. However, we had an unexpected finding from the analytics; thecardiovascular items were significantly more diffcult than the pulmonary items. Thisresult has implications for a team-taught medical school curriculum given the source ofthe difference could be the difference in teaching style, the difference in content or thedifference in item writing. We therefore are beginning an exploration of the differencein item analysis and possible impacts on student evaluations. The important of this lineof inquiry is that first, consistency in item diffculty potentially impacts a competencybased medical curriculum and second, how students perceive differences in itemdiffculty has the potential to affects instructor evaluations and therefore promotionand tenure.

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.
Smooth Muscle-Specific Knockout of LRRC8A Anion Channels Improves Vasodilation in Renal Arteries from Diabetic Mice
Authors: Choi Hyehun , Panja Sourav , Nguyen Hong-Ngan , Webb R. Clinton , Lamb Fred
Published: May 2024

Leucine Rich Repeat Containing 8 (LRRC8) family proteins (LRRC8A, B, C, D and E) comprise volume-regulated anion channels (VRACs). We previously have shown that knockout (KO) or block of LRRC8A anion channel attenuates reactive oxygen species (ROS) production by Nox1, impairs TNFα-induced inflammation, and increases vascular relaxation in mesenteric arteries. These changes are associated with reduced RhoA activation. Diabetic (db/db−/−) mice have previously been shown to develop vascular dysfunction that is characterized by increased ROS production and enhanced RhoA activation. Diabetic nephropathy causes chronic renal disease and can lead to end-stage renal failure. Oxidative stress plays a role in both the initiation and progression of this process. We hypothesized that LRRC8A KO would protect vascular function in db/db−/− mice and promote vascular relaxation in renal arteries. Smooth-muscle specific LRRC8A KO mice were created in a db/db−/− background. Renal arteries were isolated from db/db−/− WT and db/db−/− LRRC8A KO mice vascular contraction and relaxation were measured. Contractile responses to phenylephrine (PE) were unaltered in LRRC8A KO compared to WT vessels. However, both endothelium-dependent (acetylcholine, ACh) and -independent (sodium nitroprusside, SNP) relaxation were increased in LRRC8A KO compared to WT rings that were contracted with PE (Emax ACh: WT 76.8 ± 5.5 vs. KO 92.2 ± 3.3 %, LogEC50 SNP: WT -7.6 ± 0.14 vs. KO -8.4 ± 0.14, n = 4-5, * p<0.05). These data demonstrate preserved vasodilation in smooth muscle-specific LRRC8A KO blood vessels. This may lead to increased renal blood flow in the setting of db/db−/−-related diabetes. Ongoing work will determine if improved vasodilation is associated with preserved renal function in these animals. If so, VRAC inhibition may provide a novel therapeutic approach to the prevention and treatment of diabetes-induced renal dysfunction.

This work was supported by DK132948 and HL160975.

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.
Unveiling the roles of dietary Tryptophan and Arginine metabolism in Lactobacillus rhamnosus GG-mediated barrier protection
Authors: Antonio Jayson , Suntornsaratoon Panan , Flores Juan , Ambat Jayanth , Bala Ajitha , Jones Abigail , Li Wei Vivian
Published: May 2024

Inflammatory bowel disease (IBD) is often characterized by increased intestinal paracellular permeability and abnormalities in tight junctions (TJ). IBD patients commonly exhibit reduced serum tryptophan (TRP) levels. Furthermore, animal models on low-TRP diets are more susceptible to chemically induced intestinal inflammation, while those on high-TRP diets show reduced inflammation. The interaction between TRP and gut microbiota in reinforcing the intestinal barrier warrants further investigation. To address this, we introduced Lactobacillus rhamnosus GG (LGG), known for enhancing the gut barrier, and PBS as a control into germ-free mice fed TRP-suffcient or -deficient diets. Our analysis of the mouse ileal transcriptome revealed dramatic upregulation of key genes in arginine metabolism only in LGG-TRP mice, particularly of argininosuccinate lyase ( Asl) that catabolizes argininosuccinate (ASA). Interestingly, our in-silico analysis of human IBD data GEO 179285 transcriptome showed marked dysregulation of similar genes, including inappropriate increases in ASA synthetase ( Ass1). Moreover, this unique expression pattern in the mouse ileum was TRP-dependent and specific to LGG, and not observed in mice monocolonized with pathobiont Ruminococcus gnavus or specific pathogen-free mice. LC-MS analysis of fecal and serum metabolites in LGG-TRP mice revealed elevated levels of fecal arginine, glutamine, and aspartate, suggesting their involvement in host arginine biosynthesis, along with significant reductions in serum ASA levels. ASA was highly negatively correlated with numerous TJ genes, suggesting its potential to compromise barrier function. Indeed, treating mouse enteroids with ASA enhanced dextran permeability, exacerbated LPS disruption of the gut barrier, and decreased expression of TJ genes Ocln and Tjp1. Furthermore, elevated serum ASA and decreased colonic ASL levels were observed in colitis-afflicted mice, perturbing gut homeostasis, as indicated by increased fecal lipocalin-2 and delayed colitis recovery after intraperitoneal ASA administration. We propose that LGG-TRP stimulates gut-mediated ASA turnover as evidenced by substantial increases in Asl levels. Interestingly, LGG alone reduced ASA concentration in the culture medium under anaerobic and aerobic conditions. Collectively, our study identifies ASA as a potential biomarker of gut inflammation and enhanced permeability. Moreover, we highlight the potential of LGG-TRP therapy for IBD-associated leaky gut conditions, offering novel insights for gut health interventions.

NIHR01-AT010243 (NG,RF), R01DK119198 (NG), NSF 1754783 (RF).

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.
Exercise Training Mitigates Inhibition of Skeletal Muscle Mitochondrial Respiration with Empagliflozin Treatment in Male and Female Mice
Authors: Murphy Michael , McGowan Erin , Batterson Philip , Brim-Edwards Jackson , Newsom Sean , Robinson Matthew
Published: May 2024

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are antihyperglycemic drugs designed to lower renal glucose reabsorption, yet recent evidence indicates that SGLT2i have off-target effects on skeletal muscle to inhibit mitochondrial respiration. Such inhibition raises important questions regarding the interaction of SGLT2i and exercise on regulation of skeletal muscle mitochondrial metabolism. The purpose of the current study was to test the hypothesis that SGLT2i treatment (empagliflozin, EMPA) would blunt improvements to skeletal muscle mitochondrial oxidation capacity following aerobic training. Male and female C57BL/6J mice consumed a western diet (40% kcal from fat) for 8 weeks, then performed an additional 8 weeks of either treadmill training (5 times per week progressing up to 23 m/min) or remained sedentary. During the intervention period, all mice consumed either western diet or western diet enriched with EMPA (10mg/kg diet) in a 2x2 design (n=10/group for each sex). We isolated mitochondria from quadriceps muscles collected 72 hours after the final training session (or rest) and measured ex vivo mitochondrial substrate oxidation capacity using high-resolution respirometry. There was an interaction between exercise and EMPA (p=0.037) on complex I-II respiration whereby sedentary mice had lower respiration following EMPA versus untreated (-17% p=0.01) while exercise-trained mice had similar respiration between EMPA and untreated. The interaction was less prominent in complex I-supported respiration (p=0.06) or complex-II alone (p=0.09). Our results show that, contrary to expectations, EMPA treatment did not impair mitochondrial adaptations to exercise training. Instead, exercise training prevented the suppression of mitochondrial respiration during EMPA treatment. These findings indicate that aerobic exercise has positive effects on the off-target inhibition of mitochondrial respiration by SGLT2i.

Supported by funding from the Collins Medical Trust (Wilsonville, Oregon) awarded to Matthew Robinson.

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.
Effect of disturbances on heart rate of captive loggerhead turtles
Authors: Williams Cassondra , Sato Katsufumi , Ponganis Paul
Published: May 2024

Diving animals are subject to disturbances within their underwater habitat, such as interactions with fisheries, vessel traffc and increased noise in the ocean. Research on the effect of disturbances on marine mammals and birds suggest stress related to disturbances can result in either increased or decreased heart rates. However, how disturbances affect endangered or threatened marine turtles is largely unknown. Relying on behavioral data is insuffcient because animals may respond physiologically to a stressful event but demonstrate no change in behavior. To assess how marine turtles respond to disturbances, we examined the heart rate of subadult loggerhead turtles (43.5 ± 9.1 kg) that were incidentally captured by set nets in or near Otsuchi Bay, Japan. Heart rate was measured in turtles at rest in shallow tanks (n=4), resting out of water (n=4), actively feeding (n=4) and during transport in a car (n =3) using self-contained ECG data loggers. Heart rate during car transport was significantly higher than all other categories (F = 80.9, p< 0.001). Mean heart rate during transport was at least 15 beats min−1 higher than any other category, even though turtles were typically calm during transport. The mean time for heart rate to recover to resting in water heart rate was 58 minutes; however, heart rate recovery varied widely and was likely dependent on post-transport activity. While previous research showed heart rate during routine activities in loggerhead turtles was driven by activity level, these results suggest that, during stressful events, heart rate can increase dramatically even though behaviorally, turtles appear quiescent.

National Science Foundation, IOS-1121324.

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.
LRRC8A-VRAC modulates the contractile response by managing the superoxide anion influx in diabetic vasculogenic erectile dysfunction
Authors: Vieira Dos Santos Cintia , Rodrigues dos Passos Rinaldo , Choi Hyehun , Panja Sourav , Wilczynski Stephanie , Carneiro Fernando , Lamb Fred
Published: May 2024

Introduction: Erectile dysfunction (ED) may be an early marker for cardiovascular diseases, and it is often associated with an hypercontractility of the corpus cavernosum (CC) and pudendal artery (PA) because of increased reactive oxygen species (ROS). Leucine Rich Repeat Containing 8 (LRRC8) Volume Regulated Anion Channels (VRACs) regulates Nox1 and modulates the influx of extracellular superoxide anion (O2•-), contributing to the creation of an oxidized domain, enhancing calcium sensitivity of the smooth muscle which promotes contraction. Objective: We hypothesize that downregulation of NOX1 or LRRC8A would decrease the contractile responses to phenylephrine (PE) and electrical field stimulation (EFS) in the CC, PA and mesenteric resistance artery (MRA) of diabetic mice (dbdb−/−). Methods: The CC and PA of diabetic (dbdb−/−) mice were mounted in myographs. The contraction elicited by PE or EFS was performed in the presence of apocynin (non-selective NOX inhibitor) and GKT137831 (NOX1/4 inhibitor). In LRRC8A KO dbdb−/− mice, contractions to PE and EFS were obtained in the absence or in the presence of GKT137831.Results: In the CC, the maximal contraction to PE was increased in dbdb−/− animals, and in the presence of 3 mM of apocynin, the contractile response was markedly diminished in both control and dbdb−/−. Incubation with GKT137831 reduced the contraction elicited by PE only in the dbdb−/− group (68 ± 9% of the maximal contraction), whereas in the control group this reduction was not significant (82 ± 14% of the PE-maximal contraction). In the PA, the potency of PE was increased in the dbdb−/− group, and apocynin 1mM restored the contraction to normal levels. In the LRRC8A KO dbdb−/− mice, the contraction to PE in the MRA and PA was reduced by 30% compared to dbdb−/−. The response to EFS in CC was similar to dbdb−/−, however, GKT137831 reduced the contraction to EFS with lesser magnitude of inhibition in the LRRC8A KO dbdb−/− mice (35% of inhibition) compared to dbdb−/− mice (50% of inhibition), suggesting that the participation of O2•- in the contractile response was reduced by the lack of functional LRRC8A. Conclusion: LRRC8A modulates the contractile response by managing the influx of reactive oxygen species (ROS) in smooth muscle cells. Inhibition of LRRC8A may be a therapeutic target to prevent hypercontractility of arteries and CC in conditions where there are marked increases in ROS production, such as diabetes.

NIH – R01 132948; Institute on Cardiovascular Disease Research, University of South Carolina.

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 Influence of Resting Retrograde Shear Rate on Endothelial Function as Assessed by Flow Mediated Dilation
Authors: Alhalimi Taha A. , Trotter Claire E. , Velusamy Prema , Nandadeva Damsara , Fadel Paul J.
Published: May 2024

Shear stress profiles are an important determinant of endothelial function. Unidirectional blood flow enhances mean shear and protects endothelial function, whereas increased retrograde and oscillatory shear favors a proatherogenic environment. In this regard, acutely increasing retrograde shear has been shown to impair endothelial function. Also, previous studies have reported an elevation in retrograde shear in older adults that has been suggested to contribute to impaired endothelial function with age. However, the impact of having elevated retrograde shear at rest on endothelial function remains unclear. Therefore, we aimed to assess the associations between resting shear patterns and endothelial function, as measured by flow-mediated dilation (FMD) in a cohort of young and older adults. We hypothesized that higher retrograde shear rate and oscillatory shear index at rest would be related to a lower FMD value. Method: A total of 60 participants, 30 young adults (24 ± 5 years) and 30 older adults (62 ± 9 years), were studied. Resting brachial artery blood flow was measured using duplex Doppler ultrasound and retrograde shear rate and oscillatory shear index were calculated. Brachial artery FMD was used as a measure of endothelial function. Pearson correlations were used to investigate the associations between FMD, resting shear patterns, and age. Result: FMD was significantly lower in older compared to young adults (4.9 ± 2.7% vs. 7.6 ± 3.2%, p < 0.01). Both retrograde shear rate and oscillatory shear index tended to be greater in older adults (-20.7 ± 15.1 s−1 vs. -15.2 ± 17 s−1, p = 0.062, and 10.7 ± 8% vs. 7.9 ± 8.0%, p = 0.056, respectively). FMD was not correlated with retrograde shear rate (r = -0.18, p = 0.17), or oscillatory shear index (r = -0.21, p = 0.11) in the entire cohort or in the young and older group alone. However, FMD, retrograde shear rate, and oscillatory index were moderately correlated with age: FMD (r = -0.45, p < 0.01), retrograde shear rate (r = -0.32, p = 0.012), and oscillatory shear index (r = 0.33, p < 0.01). Conclusion: These preliminary results suggest that resting retrograde shear and oscillatory shear index are not associated with reduced endothelial function in a cohort of young and old adults. Nevertheless, age-associated reductions in endothelial function and elevated retrograde shear were observed.

This project was supported by the College of Nursing and Health Innovation.

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.
Carotid body-mediated chemoreflex drive predicts the development of HFpEF in mice
Authors: Pereyra Katherin
Published: May 2024

Heart failure with preserved ejection fraction (HFpEF) is a prevalent pathophysiological condition affecting millions of people worldwide. Several factors have been pointed out to play a role in the development of HFpEF; however, there are no molecular/physiological variables that can predict the incidence of HFpEF. Interestingly, carotid body (CB) chemoreceptors have been implicated in worse outcomes in reduced ejection fraction HF. Then, we hypothesized that CB chemoreflex sensitivity may offer prognostic value in HFpEF. Accordingly, we aimed to study whether high chemoreflex drive predicts the development of HFpEF in mice. A longitudinal study was performed in adult C57BLJ6 mice (P90) that underwent 16 weeks treatment with a high fat diet (60% high fat diet, HFD) and a nitric oxide synthase blocker (L-NAME 0.6 g/L) to induce HFpEF. Mice were recorded for cardiac/hemodynamic and ventilatory function before the onset of HFD and L-NAME treatment by using 2D-echocardiography, tissue doppler imaging, blood pressure and whole-body plethysmography, respectively. At 16 weeks after HFD+L-NAME all mice were recorded again. CB-chemoreflex drive was assessed by the hypoxic ventilatory response (HVR, FiO2»10%). We found that »50% of total mice (n=24) develop HFpEF after 16 weeks of HFD+L-NAME as evidenced by a significant (p<0.05) increase in the E/A ratio (1.60±0.09 vs. 1.30±0.01 mmHg, HFpEF vs. nonHFpEF), blood pressure (MAP: 98.7±1.9 vs. 88.4±1.4 mmHg, HFpEF vs. nonHFpEF) and body weight (31±1 vs. 29±0 g, HFpEF vs. nonHFpEF). Remarkably, a higher HVR before the onset of HFD+L-NAME was closely associated with the prevalence of HFpEF. Indeed, (4/5) mice that displayed a high HVR chemoreflex (³0.15 ΔVE/FiO2%) develop HFpEF after 16 weeks of HFD+L-NAME treatment. Our results showed for the first time that CB-mediated chemoreflex sensitivity predicts the development of HFpEF and support the notion that peripheral chemoreflex drive may be useful to evaluate the risk of developing HFpEF.

Supported by Fondecyt 1220950.

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.
Hypoxia Exposure Fine-Tunes Mitochondrial Function in Primary Dermal Fibroblasts Derived from Loggerhead Sea Turtles
Authors: Arango B. Gabriela , Ensminger David C. , Godard-Codding Celine , Vázquez-Medina Jose Pablo
Published: May 2024

Sea turtles are constantly exposed to changes in oxygen tension derived from extended breath-hold diving, but the cellular-level response to such changes is not completely understood. Most studies in hypoxia-tolerant reptiles have focused on the freshwater turtle Trachemys scripta, which responds to anoxia by inducing metabolic rewiring and preserving mitochondrial integrity, facilitating effcient mitochondrial respiration during reoxygenation. Here, we derived primary dermal fibroblasts from loggerhead sea turtles and western fence lizards to study the bioenergetic cellular response to hypoxia exposure in diving and non-diving reptiles. Cells from both species stained positive for the fibroblast markers vimentin and PDGFRb and responded to hypoxia exposure (0.1% O2) by accumulating HIF-1α. We measured oxygen consumption rates (OCR) in intact cells using Seahorse technology. We found that basal, maximal, and spare respiratory capacity was lower in lizard than in loggerhead cells at 26oC under normoxic (room air) conditions (p < 0.0001). Exposure to short (1h) and long-term hypoxia (24h) altered mitochondrial function in both species. Maximal and spare respiratory capacity were lower in loggerhead than in lizard cells (p < 0.01) after 1h hypoxia followed by 1h reoxygenation. In contrast, basal and maximal respiratory capacity was higher in loggerhead compared to lizard cells after 24h hypoxia (p < 0.04). Nonetheless, the overall OCR after 24h hypoxia in both species was lower than that observed after 1h hypoxia. Overall, there was a significant reduction in cellular respiration in both species from short-term to long-term hypoxia exposure. In lizard cells, basal OCR decreased by a factor of three while maximal OCR decreased by a factor of 4.5. In loggerhead cells, both the basal and maximal OCR decreased by a factor of two. Our results demonstrate species-specific regulation of cellular respiration after hypoxia exposure. Remarkably, loggerhead cells show a steady downregulation of cellular respiration in response to hypoxia exposure and faster recovery after extended hypoxia (24h) than lizard cells, aligning with the remarkable hypoxic tolerance exhibited by sea turtles, which can endure up to 7 hours of breath-holding underwater. Understanding the cellular mechanisms that drive hypoxic tolerance in diving animals can provide insights for treating human conditions characterized by hypoxia signaling.

Ford 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.
Investigation of the Role of Aging on Pulmonary Microvascular Endothelial Cell Barrier Function During Mechanical Ventilation
Authors: Manji Aminmohamed , Mehta Sanjay , Wang Lefeng , Pape Cynthia , McCaig Lynda , Veldhuizen Ruud , Gill Sean
Published: May 2024

Elderly individuals have substantially elevated morbidity and mortality following pulmonary insult that require mechanical ventilation (MV) to sustain respiratory function. It is not known if an altered response to MV contributes to the worsened outcomes in the elderly. MV is associated with injury to pulmonary microvascular endothelial cells (PMVEC), leading to a compromised vascular barrier, and fluid and protein leakage within the tissue. However, the precise impact that age has on the vascular endothelium during MV is unknown. We hypothesized that aging augments PMVEC barrier dysfunction during MV. To address this hypothesis, young and aged mice were ventilated at a tidal volume of 20 mL/kg for 3 hours. To assess microvascular permeability, lungs were lavaged and abundance of the serum protein, immunoglobulin M, within the lavage fluid was measured. Lung tissue was dissociated into single cells and RNA was collected for single-cell RNA sequencing (scRNAseq). Subsequent analysis was performed using the Seurat package in R to give insight into the role of specific cell types, with a particular emphasis on microvascular endothelial cells. To directly assess molecular mechanisms directly in the cells, PMVEC were isolated from a separate cohort of non-ventilated young and aged mice and cultured in vitro. Cells were grown to confluency, then assessed for barrier integrity by Evans blue-labelled albumin leak across monolayers and immunofluorescence staining of cell junctional adherens and tight junction proteins, VE-cadherin and claudin-5. Compared to young, aged-ventilated animals had a significant increase in immunoglobulin M in their lavage fluid. Analysis of scRNAseq data revealed more robust activation and inflammation in the endothelial cells from aged animals following MV. Endothelial monolayers from aged animals in vitro exhibited a significant increase in albumin flux, which was associated with poor VE-cadherin and claudin-5 junction formation. In conclusion, PMVEC from aged mice exhibit compromised barrier function, leading to augmented permeability following MV. The age-dependent loss in barrier function appears to be due to an impaired ability to re-establish functional cell-cell junctions. These findings suggest that the aged vascular barrier is more susceptible to injury from MV, due to impaired PMVEC cell-cell junction integrity. Our results may highlight molecular pathways involved in predisposing aged individuals to worsened outcomes during MV, which can help in developing targeted therapeutics.

Funded by Lawson Health Research Institute, CIHR, the Ontario Graduate Scholarship, and Western University.

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.
Influence of Commonly-Encountered Participant Behavior on Cardiovascular Measures during Physiological Testing
Authors: McLaurin Natalie , Alhalimi Taha , Ramos Andrea , Trevino George , Tanaka Hirofumi
Published: May 2024

Objective: When conducting laboratory testing, it is essential for participants to rest quietly in the supine posture without much movement. This is to establish a stable baseline to minimize external interference and distractions that could affect physiological measures. However, it is rather common that some participants start talking to investigators, fall asleep, or use cell phones for texting during the resting period. It is also common to observe some participants change their posture to side laying to make themselves more comfortable. The extent to which these common laboratory encounters influence cardiovascular outcome measures such as blood pressure and arterial stiffness has not yet been studied. Methods: A total of 55 adults (16 men and 39 women, 36±15 years) were studied under the following seven conditions: 1) quiet supine rest, 2) pretending to sleep, 3) while and 4) after talking to investigators, 5) during and 6) after cell phone use for texting, and 7) lying on the side. Each condition was separated by 5 minutes. The order of the conditions was randomized. Systolic and diastolic blood pressure (BP), heart rate, brachial-ankle pulse wave velocity (baPWV), and carotid-femoral PWV (cfPWV) were measured during these conditions. Results: Compared with quiet rest (61±10 bpm), heart rate was elevated (p<0.05) when the participants were talking to the investigators (65±10 bpm) and texting on cell phones (69±15 bpm). Both systolic and diastolic BP were 3-4 mmHg greater when they were talking to the investigators but 4-5 mmHg lower in the ‘side lying’ position compared with quiet rest. In the ‘side lying’ condition, baPWV was not affected but cfPWV was not able to be measured in 16 participants resulting in a 38% failure rate. baPWV was greater (p<0.01) while and after the participants were talking to investigators. cfPWV was not able to be measured during talking but was not affected when it was assessed after talking. Pretending to sleep and texting on a cell phone did not significantly influence any of the BP and PWV measures. Conclusions: Talking during the testing period significantly increases all the cardiovascular measures assessed in the present study. However, pretending to sleep and cell phone texting do not appear to influence them.

There was no funding source for this study.

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.
Vagal nerve and sympathetic nerve activity in response to glucagon-like peptide-1 (GLP-1) receptor stimulation in conscious rats
Authors: Miki Kenju , Ikegame Shizuka , Yoshimoto Misa
Published: May 2024

GLP-1 (Glucagon-Like Peptide-1) is a type of gastrointestinal hormone that plays an integral role in regulating glucose homeostasis and appetite control. GLP-1 receptors are expressed throughout the body, and it has been suggested that GLP-1 can be detected by vagal afferent nerve activity, leading to changes in sympathetic nerve activity. However, the details of the effects of GLP-1 receptor stimulation on autonomic nerve activity have not been reported. Therefore, this study investigated the effects of different sites of GLP-1 receptor stimulation on autonomic nerve activity by administering GLP-1 receptor agonists via three routes: intravenous (IV), intraportal vein (iport), and intraperitoneal (iperi). Male Wistar rats were chronically implanted with electrodes, catheters for measuring cervical vagal activity, renal and lumbar sympathetic nerve activity, electroencephalogram, electromyogram, electrocardiogram, arterial pressure, sensors for tissue fluid glucose concentration, and catheters for drug administration in the vein, portal vein, and abdominal cavity. Exendin-4, a GLP-1 receptor agonist, was administered to conscious rats via one of the following routes: intravenous, intra-portal vein, or intra-abdominal. Cervical vagal activity was increased in all routes of Exendin-4 administration. Renal sympathetic nerve activity was rapidly decreased by Exendin-4 administration and gradually recovered to pre-administration levels. There were no significant differences in renal sympathetic nerve activity among the different routes of Exendin-4 administration. On the other hand, lumbar sympathetic nerve activity increased slowly after Exendin-4 administration through the iperi and iport routes, while it decreased initially, then gradually increased following administration through the IV route. These results demonstrate that stimulation of GLP-1 receptors by Exendin-4 increases vagal nerve activity, decreases renal sympathetic nerve activity, and produces regionally different responses in lumbar sympathetic nerve activity depending on the site of stimulation.

JST (JPMJMS2023).

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.
Estrogen Metabolites Modulate Airway Hyperreactivity in a Murine Model of Asthma
Authors: Kumar Ashish , Reza Mohammad Irshad , Ambhore Nilesh , Balraj Premanand , Sathish Venkatachalem
Published: May 2024

Objective: Airway hyperreactivity (AHR) and remodeling are the key contributors to airway changes in asthma resulting in airway narrowing and resistance to airflow. Sex-steroid signaling, especially estrogen’s differential role in asthma undoubtedly questions its prime involvement in regulating airway structure and function in context to asthma. Evidence from cardiovascular (CV) and reproductive systems suggests that estrogen metabolites particularly 2-hydroxyestradiol (2HE) and 16α-hydroxyestradiol (16αHE2) influence a multitude of cellular functions. Accordingly, the aim of this study is to determine how estrogen metabolites regulate AHR and remodeling using a mouse model of asthma. Methods: WT C57BL/6J (male and female) mice were procured from Jackson Laboratory. Experimental animals were administered with PBS, 2-HE (2 mg/kg), 16αHE2 (2 mg/kg) with/without MA intranasally on alternate days for 28 days. On day 29, mice were anesthetized and subjected to SCIREQ flexiVent to measure Lung mechanics like airway resistance (Rrs), elastance (Ers), and compliance (Crs). Following this, broncho-alveolar lavage (BAL) was performed for differential leukocyte count (DLC) and lung tissue samples processed for histology using hematoxylin and eosin (H&E) staining and Sirius-red and fast-green (SRFG). Results: MA-challenged group increased airway Rrs and reduced Crs in response to methacholine (MCh) in both male and female mice with profound effects in female mice. Animals exposed to MA and administered with 16αHE2 showed significant increase the Rrs while 2-HE downregulated the MA effect. The exacerbated effect of 16αHE2 on Rrs was significantly higher in MA-challenged female mice compared to male mice. Histology study including H&E and SRFG stained lung sections show increased ASM mass in 16αHE2 exposed mixed MA challenged mice. Whereas 2HE reversed MA induced effect. DLC in BAL showed increased neutrophils and eosinophils in MA challenged mice, this was attenuated by 2HE. Conclusion: This study highlights the distinct role of estrogen metabolites in regulating airway hyperresponsiveness and remodeling in the context of asthma. Thus, providing possible therapeutic potential for observed sex differences in asthma.

Acknowledgment: Supported by NIH grant R01-HL146705 (Sathish).

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.
Pseudocannabinoid H4CBD Reduces Cardiac Damage Indicator 4HNE in OLETF (Otsuka Long Evans Tokushima Fatty) Rats
Authors: Hernandez Garcia Marisol , Wilson Jessica N. , Mendez Dora A. , Ortiz Rudy , Mascal Mark
Published: May 2024

Cardiovascular disease (CVD) is a leading cause of death globally and MetS is an associated precursor of CVD. Of the 6 known cluster factor conditions of MetS, obesity, and poor glucose tolerance are known to contribute to high lipid peroxidation, which can contribute to the generation of damaging free radical species and a pro-oxidant system. Cannabidiol (CBD) is a known antioxidant and a growing understanding of CBD analogs and pseudocannabinoids, like H4CBD, implicate similar antioxidant effects. However, little is known about the effects of CBD analogs on MetS-associated cardiac tissue damage. To better understand these effects during extreme metabolic dysfunction, 41-weeks-old animals were assigned into three groups, (n=8/group): (1) one-lean-strain control, Long Evans Tokushima Otsuka (LETO), (2) untreated OLETF, and (3) OLETF + H4CBD (200 mg/kg/day x 4 weeks). Our hypothesis focuses on the prospect that ongoing treatment with H4CBD in a MetS model using Otsuka Long-Evans Tokushima Fatty (OLETF) rats will reduce indicators of lipid peroxidation including 4-hydroxynonenal (4HNE), a toxic end product of lipid peroxidation. After the 4-week treatment, cardiac tissue was analyzed for 4-hydroxynonenal (4HNE) protein expression. We found that H4CBD decreased cardiac 4HNE protein expression in treated OLETF rats by 68% (p<0.05) compared to OLETF control, which indicates H4CBD attenuated cardiac lipid peroxidation overall. Although the 4-week treatment of H4CBD was not suffcient to ameliorate MetS-associated hypertension, the reduction of 4HNE suggests that the attenuation of cardiac damage is independent of arterial pressure. These data indicate that H4CBD and its derivatives hold promise for therapeutic use in managing CVD and related metabolic syndrome-associated pathologies.

Undergraduate Research Training Initiative for Student Enhancement (U-RISE), Center for Medical Cannabis Research.

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.
Addressing Disparities Between Physician Rated and Self-Reported Dyspnea Using Machine Learning
Authors: Mkrtchyan Karapet , Lohn Borena , Qazi Anser , Ma Shujie , Heinrich Erica
Published: May 2024

Nearly 50% of intensive care and 25% of tertiary care patients experience dyspnea, or the sensation of unsatisfied breathing. Dyspnea decreases quality of life, impacts clinical outcomes, and can have long standing psychological consequences for some patients. Current methods of identifying dyspnea severity (such as the respiratory distress observation scale or RDOS) lack suffcient quantifiable measurements of dyspnea to accurately predict its severity. In our testing, while the RDOS does have predictive power, it frequently produces underestimates compared to self-reported dyspnea severity (r = 0.32; p = 0.0081). Furthermore, dyspnea severity can change throughout the day, requiring healthcare professionals to conduct RDOS evaluations multiple times to attempt to meet patient needs. Therefore, there is an urgent need for continuous, accurate monitoring of dyspnea severity in the hospital setting. To address this need, we are using non-invasive data collected during induced bouts of dyspnea to train a machine learning (ML) algorithm in dyspnea prediction. We employ a steady-state end-tidal forcing breathing system and adjust end-tidal gas tensions manually while collecting PO­­­­2, PCO2, SpO2, and ventilation data. Preliminary findings show several physiological and demographic factors independently correlate to dyspnea severity, including BMI (r = 0.49; p = 0.007), end-tidal PCO­­2 (r = 0.33; p = 0.008), and inspired PO2 (r = -0.25; p = 0.043). We achieved an accuracy of 84%, 83.3%, and 82% in-dataset predictions using k-nearest neighbor, random forest, and logistic regression approaches respectively. Several physiological biomarkers and demographic factors were used as inputs and self-reported dyspnea was used as the predicted output. These findings show promise for the use of ML in dyspnea prediction. With further testing and use of a broader participant population, it may be possible to use ML models such as these to improve patient outcomes and overall quality of life.

University of California, Riverside.

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.
A Hypovolemic Infusion of Human Methemoglobin in Golden Syrian Hamsters Provides Insight on its effect on the Microcirculation
Authors: Munoz Carlos , Lucas Daniela , Martinez Jacinda , R. Muller Cynthia , Govender Krianthan , Palmer Andre F. , Cabrales Pedro
Published: May 2024

Introduction: Hemoglobin (HbFe(II)) plays a crucial role in transporting oxygen to tissues for metabolic needs. However, this protein isn't just an oxygen carrier; it also regulates vascular tone and inflammation by its redox coupling with methemoglobin (HbFe(III)). Methemoglobin's oxidized form, Fe (III), possesses the potential to produce water from oxygen as a free energy reaction. It functions as a nitrite reductase, regulating the oxygen level in the blood and controlling vascular tone by generating nitric oxide from nitrite, thereby increasing blood flow when oxygenated hemoglobin decreases. If methemoglobin can't be reduced, it leads to the dissociation of tetrameric hemoglobin into αβ dimers, releasing heme and iron into circulation. Methods: The study involved Golden Syrian Hamsters with dorsal skin fold window chambers, observing acute methemoglobin effects via hypovolemic infusion (10% of the animal’s blood volume) compared to human hemoglobin and a lactated ringer's control. Microhemodynamics, mean arterial pressure, heart rate, blood gases, and blood properties were measured. Results: Methemoglobin did not significantly affect MAP and HR but increased arteriole diameters by 5% and venule diameter by 15% compared to baseline. However, it caused a 50% reduction in functional capillary density compared to baseline, alongside significant cardiac and kidney inflammation. Conclusion: The study concludes that a hypovolemic infusion of methemoglobin induces vasoreactivity but results in poor microcirculatory pressure and inflammation in vital organs. This demonstrates the delicate balance and potential adverse effects associated with alterations in the hemoglobin redox state and highlights the importance of maintaining its balance for vascular and organ health.

Project number: R01HL159862 Project number: R01HL162120.

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.
Potential Role of Diabetes in Impaired Semaphorin-Mediated Maintenance of Epithelial Barrier Properties
Authors: Caceres Paulo
Published: May 2024

Microvasculature-secreted factors create a local niche for tissue specialization and homeostasis. Diseases like diabetes are considered a microvascular disease. However, the consequences of microvascular alteration in surrounding tissues like epithelial barriers have not been suffciently explored. The objective of this study is to determine whether a cell-cell communication protein, Semaphorin-3E (Sema3E), which we have previously found increased in diabetic mice and in endothelial cells cultured on high glucose, impairs the barrier properties of epithelial cells. We determined by ELISA that HUVEC endothelial cells secreted Sema3E (7.8 ±1.8 pg/sq.cm/day) and while mannitol osmolality control 15mM had no effect, high glucose (25mM) increased Sema3E secretion 6-fold (ANOVA, p<0.01). To test the effect of Sema3E in the tight junction barrier properties of epithelial cells, we measured trans-epithelial electrical resistance (TEER) in Calu-3 epithelial cells cultured in trans-well permeable support. We found that 200ng/ml of recombinant Sema3E inhibited the acquisition of TEER over the course of 2 weeks (vehicle: 803 ± 31 Ω/cm^2 vs. Sema3E: 465 ± 15 Ω/cm^2; t-test p<0.01) The weakening of tight junctions was due to decreased presence of Claudin-2 at the cell surface as measured by surface biotinylation (Surface/intracellular ratio= vehicle: 0.356 ± 0.043 vs. Sema3E: 0.020 ± 0.003; t-test p<0.01). Consequently, the polarity of Calu-3 cells was also impaired as we determined by measuring the polarized distribution of the basolateral protein E-cadherin. We observed a reduction of basolateral E-cadherin from 88 ± 3% (vehicle) to 65 ± 6% (Sema3E), t-test p<0.05. Finally, to determine whether surface Claudin-2 expression was decreased in epithelial cells of diabetic mice, we performed surface biotinylation in freshly isolated kidney renal tubules. We observed that the surface/intracellular ratio of Claudin-2 was decreased by 76% in kidney tubules from type-1 diabetic mice (Akita strain), compared to healthy control mice (control: 4.23 ± 1.44 ratio vs. Akita: 1.03 ± 0.16 ratio, t-test p<0.05). We conclude that glucose stimulates Sema3E secretion from endothelial cells, and this signal protein impairs the epithelial barrier properties of epithelial cells by reducing Claudin-2 presence at tight junctions. Reduced surface Claudin-2 may be a feature of diabetic epithelial cells.

American Heart Association NIH.

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.
Mammalian target of rapamycin mediates expression and activity of ADAM 17 in diabetic kidney disease
Authors: Mack James , Faiz Najwa , Abraham Sachin , Ford Bridget
Published: May 2024

Purpose: Previous data have illustrated a role for the matrix metalloprotease A Disintegrin And Metalloprotease 17 (ADAM17), known to cleave growth factors and cytokines, in renal cell injury in diabetes. The goal of this study was to identify upstream regulators of ADAM17 in the cascade of events contributing to extracellular matrix accumulation in diabetic nephropathy. Rationale: Diabetic kidney disease is a serious complication faced by type 1 and type 2 diabetic patients alike. Albuminuria and extracellular matrix accumulation are prominent features of the disease and this accumulation of extracellular matrix is a contributing factor to renal fibrosis and decline in renal function. The mechanisms involved in the pathogenesis of diabetic kidney disease have not been completely identified. Methodology: Age and weight-matched Sprague Dawley rats were obtained from Harlan Laboratories (Indianapolis, IN). Type 1 diabetes was induced through tail vein injection of streptozotocin. After rats were determined to be diabetic by blood glucose measurement, rapamycin treatments were administered intraperitoneally for two months. Both kidneys were removed and frozen in liquid nitrogen for microscopy and experimental analyses or formalin fixed for morphometric imaging at the experimental endpoint. Kidney cortex homogenates were used for western blot analyses and enzymatic activity assays. Findings: Using the mTOR complex 1 inhibitor rapamycin, it was determined that increased ADAM17 enzymatic activity and ADAM17 protein expression is dependent on mTORC1 in streptozotocin-induced type 1 diabetic rats. Inhibition of mTORC1 with rapamycin abrogated the increase in collagen IV α 2 protein expression observed in diabetic rat cortex. Additionally, this study is the first to provide evidence that mTOR complex 1 activates ADAM17 contributing to extracellular matrix accumulation in diabetic nephropathy. Studies are continuing looking at the molecular mechanisms involved in mTOR activation of ADAM17 resulting in downstream effects in cultured human proximal tubular epithelial cells.

Research reported in this poster was supported by the University of the Incarnate Word Offce of Research and Graduate Studies.

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.