bluuebunny/crossref_metadata_2025 huggingface dataset:
Does Obesity or Hyperglycemia Alter Metabolic Endotoxemia?
Authors: Bhatwa Arshpreet , Anhê Gabriel , Anhê Fernando , Schertzer Jonathan
Published: May 2023

Obesity increases the risk of type 2 diabetes and non-alcoholic fatty liver disease, which are two interlinked diseases with a high health and economic burden. Obesogenic diets change the composition of intestinal microbes. Our objective is to move beyond associations of taxonomy and define specific microbial components that alter host immune and metabolic responses. Postbiotics are bacterial components or metabolites derived from living or dead bacteria that can modulate host immunity and metabolism. Lipopolysaccharide (LPS) is a classic example of a postbiotic that acts through toll-like receptor 4 (TLR4) to influence inflammation. Metabolic endotoxemia describes a chronic, low-level increase of LPS seen in blood during metabolic disease. However, it was recently shown that metabolic endotoxemia may be beneficial or detrimental to host metabolism depending on the type of LPS, which is dictated by different species of bacteria. It was previously unknown if obesity or hyperglycemia, is the main driver that alters metabolic endotoxemia. We hypothesized that obesity and hyperglycemia lead to an increase in the inflammatory properties of LPS found in the gut lumen and serum. We tested feces, and the systemic and portal serum obtained from mouse models of hyperglycemia (Akita+/- mice) and obesity ( ob/ob mice) for their TLR4 activation. It was found that hyperglycemia leads to increased fecal TLR4 activation, which can be reduced by lowering blood glucose in Akita+/- mice. In particular, a fed state promotes increased TLR4 activity in the serum of hyperglycemic mice. Elevated levels of TLR4 activity were observed in the serum of ob/ob mice. However, as these mice are transiently hyperglycemic, their elevated levels of blood glucose early on in their life may be a confounding factor leading to increased TLR4 activity. In conclusion, hyperglycemia is a main driver for metabolic endotoxemia and the increased inflammatory properties of LPS in the gut lumen. This research provides a framework of how specific metabolic disease characteristics influence inflammation and will help future studies looking to target the link between hyperglycemia and changes to the specific type of LPS.

Canadian Institutes of Health Research, Farncombe Family Digestive Health and Research Institute

This is the full abstract presented at the American Physiology Summit 2023 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.
Glutamine Stimulates the Proliferation, Migration, and Survival of Vascular Smooth Muscle Cells
Authors: Durante William , Liu Xiao-ming , Durante Giovanna , Peyton Kelly
Published: May 2023

Glutamine is an abundant and versatile amino acid that contributes to cellular integrity and function. Glutamine is predominantly metabolized to glutamate and ammonia by the mitochondrial enzyme glutaminase-1 (GLS1). Glutamate is subsequently converted by glutamate dehydrogenase and/or aminotransferases to α-ketoglutarate (α-KG) which feeds into the tricarboxylic acid (TCA) cycle for ATP production and amino acid and lipid synthesis, thereby fulfilling both the energetic and macromolecular requirement of cells. While glutamine is known to regulate the function of vascular smooth muscle cells (SMCs), the metabolic pathways underlying this response are not fully known. Accordingly, the present study investigated the effect of glutamine and its metabolites on vascular SMC function. Incubation of cultured rat or human aortic SMCs with glutamine resulted in a progressive increase in cell proliferation and migration that was accompanied by an increase in cellular glutamate and ammonia levels. Treatment of SMCs with the selective GLS1 inhibitors bis-2-(5-phenylacetoamido-1,3,4,-thiazol-2-yl)ethyl sulfide (BPTES) or CB-839 inhibited the stimulatory effects of glutamine. Flow cytometry experiments revealed that GLS1 inhibitors arrested SMCs in the G0/G1 phase of the cell cycle, and this was associated with a significant decline in DNA synthesis. Glutamine depletion or GLS1 inhibition also sensitized SMCs to the toxic effects of hydrogen peroxide. Interestingly, the administration of cell permeable dimethyl α-KG increased the proliferation and migration of glutamine-deprived SMCs, while the application of ammonia had no effect. In contrast, ammonia, but not dimethyl α-KG, mitigated hydrogen peroxide-mediated death of glutamine-starved SMCs. In conclusion, this study demonstrates that the metabolism of glutamine by GLS1 promotes SMC proliferation, migration, and survival. While the replenishment of the TCA cycle by α-KG contributes to glutamine-dependent growth and motility, the generation of ammonia by GLS1 promotes glutamine-conditional survival. These results identify GLS1 as a promising therapeutic target in treating diseases associated with aberrant vascular SMC phenotypes.

This work was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under Award Number R01 HL149727.

This is the full abstract presented at the American Physiology Summit 2023 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.
Impaired proteostatic mechanisms other than protein synthesis limit aged skeletal muscle recovery after disuse atrophy
Authors: Fuqua Jordan , Lawrence Marcus , Hettinger Zachary , Borowik Agnieszka , Brecheen Parker , Peelor Frederick , Bodine Sue , Dupont-Versteegden Esther , Miller Benjamin
Published: May 2023

Older individuals undergo more frequent hospitalizations and periods of bedrest compared to younger persons, causing rapid loss of muscle mass and strength. We and others have shown that old muscle fails to completely regrow following disuse, despite having similar levels of muscle loss during disuse and equal or higher myofibrillar protein synthesis during recovery. Therefore, we hypothesized that a failure of proteostatic mechanisms other than protein synthesis contributes to the inability of old muscle to fully recover after a period of disuse atrophy. Methods: Adult (10 month) and old (30 month) male F344BN rats were hindlimb unloaded for 14 days and then reloaded for up to 60 days. We used a combination of deuterium oxide (D2O) labeling, proteomics, and biochemical analyses to study proteostasis during recovery. Results: There was a failure of old muscle to maintain proteostasis as evident by a greater accumulation of insoluble protein aggregates ( 1.02 ±0.06 vs. 1.22 ±0.06, p<0.05), insoluble collagen ( 4.0 ±1.1 vs. 9.2 ±0.9, p<0.01) and higher amount of advanced glycation end products (AGEs) ( 1.0 ±0.06 vs. 1.5 ±0.08, p<0.001) compared to adult. Old muscle had higher rates of myofibrillar protein synthesis than adult muscle ( 0.029 k/day ±0.002 vs. 0.039 k/day ±0.002, p<0.0001), but also higher rates of breakdown (0.017 1/t ±0.002 vs. 0.028 1/t ±0.004, p<0.05). Differences in the synthesis of collagen were less apparent between adult and old muscle, implying that there was a failure of collagen breakdown in old muscle leading to greater accumulation. Lastly, pathway analysis of proteomic data showed that there were differences in the proteins that accumulated in aggregates between adult and old muscle, and that the synthesis of proteins that regulate proteostasis were different with age. Conclusions: Together, these data indicate that in old muscle altered proteostatic mechanisms other than myofibrillar protein synthesis led to failure to recover from atrophy. Interventions should therefore be targeted at these novel mechanisms instead of protein synthesis alone.

NIA Training Grant: 5T32AG052363-04, APS Postdoctoral Fellowship MML, F31AT01147201 ZRH, R01(NCCIH AT009268)

This is the full abstract presented at the American Physiology Summit 2023 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 spermidine on endothelial function in Systemic Lupus Erythematosus (SLE)
Authors: Kim Hyoseon , Nino Matthew , Massett Michael
Published: May 2023

Impaired endothelial function has been shown in SLE patients and lupus-prone mice. Emerging evidence supports impaired mitochondrial dynamics and mitophagy contribute to SLE and endothelial dysfunction. Spermidine is a natural polyamine that stimulates mitophagy by activating the PINK1-Parkin pathway and can improve endothelial function. However, the effect of spermidine on mitophagy and vascular function in SLE has not been explored. To address this gap, 9-week-old female lupus-prone (MRL/lpr) and healthy control (MRL/MpJ) mice were randomly assigned into one of two groups, spermidine treatment (Lpr T and MpJ T) or control (Lpr C and MpJ C). Treated mice received spermidine (3mM) via drinking water for 8 weeks. After 8 weeks of treatment, endothelium-dependent vasorelaxation to acetylcholine (ACh) and endothelium-independent vasorelaxation to sodium nitroprusside (SNP) were measured in thoracic aortas using a wire myograph. Maximal responses to ACh were significantly impaired in Lpr C (67.1 ± 8.7, n = 11) compared to Mp C (90.3 ± 3.1, n = 13) (p = 0.01). Spermidine improved endothelial function in thoracic aorta from Lpr T (90.3 ± 2.8, n = 13) compared to Lpr C (p = 0.03). Maximal responses to SNP were not significantly different across the groups. Thoracic and abdominal aortas were used for measurements of protein content (n = 3-4/group) and gene expression (n = 4/group), respectively. There were strain differences in the mRNA expression of endothelial nitric oxide synthase ( Nos3) between Lpr C (0.65 ± 0.14) and MpJ C (1.00 ± 0.16) (p = 0008). In MpJ mice, Nos3 mRNA expression was significantly higher in the aorta from the MpJ T (1.47 ± 0.39) compared to MpJ C (p = 0.04). No significant differences were found in the Nos3 expression between Lpr groups. Vascular cell adhesion molecule 1 (Vcam1) is an indicator of inflammation and is associated with atherosclerosis susceptibility. Protein content of Vcam1 was significantly lower in Lpr T (3.73 ± 0.61) compared to Lpr C (8.49 ± 2.58) (p = 0.04) and gene expression of Vcam1 was also lower in Lpr T compared to Lpr C, suggesting spermidine decreases the inflammatory responses in vessels from SLE mice. Protein content of Parkin was measured as a marker of mitophagy. Parkin was significantly lower in Lpr C (0.38 ± 0.61) compared to MpJ C (1.00 ± 0.09) (p = 0.004), suggesting lower mitophagy in aorta from SLE mice. Parkin content in Lpr T was similar to MpJ C. Collectively, these results demonstrate the beneficial effects of spermidine treatment on endothelial function in SLE mice and suggest inflammation and altered mitophagy contribute to endothelial dysfunction in SLE.

This is the full abstract presented at the American Physiology Summit 2023 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.
Dietary potassium restriction reprograms the distal tubule causing adverse metabolic consequences
Authors: Su Xiao-Tong , Reyes Jeremiah , Cornelius Ryan , Duan Xin-Peng , Wang Wen-Hui , McCormick James , Yang Chao-Ling , Nelson Jonathan , Ellison David
Published: May 2023

Low potassium (K) intake has adverse health effects, including hypertension, osteoporosis, and nephrolithiasis. Dietary K restriction rapidly activates a K switch in the distal nephron to maintain homeostasis by reducing K excretion and activating the sodium chloride cotransporter (NCC). The distal convoluted tubule (DCT) is morphologically and functionally divided into DCT1 and DCT2, with each segment specialized for a different function. Here, we define the differences between DCT1 and DCT2 transcriptionally, examine their unique responses to potassium restriction, and detrimental physiological responses in mice.The K restriction effects were examined at 3 time points, overnight (acute), 4 days (short-term), and 4 weeks (chronic). Electrophysiology was used to assess effects of acute K deprivation on basolateral K channel (Kir4.1/5.1) activity. To determine effects of K restriction for 4 days, the DCT-targeted single-nucleus RNA-sequencing (snRNAseq) approach was applied. Female NCC-Cre-INTACT (PMID: 26087164) mice were provided either normal (NK) or K deficient (KD) diet for 4 days (short-term) and kidneys were snap-frozen for targeted snRNAseq (10X Chromium, NovaSeq) (3 mice per diet, 10,000 nuclei per mouse). Effects of chronic K-restriction were assessed by serum electrolytes, tissue clearing, and western blot.Acute K restriction stimulated basolateral K channel activity in DCT1, but not in DCT2, indicating that DCT1 and DCT2 respond differently. Although both DCT1 and DCT2 express NCC, snRNAseq data showed that DCT1 and DCT2 have distinct transcriptional signatures, with DCT1 expressing genes involved in magnesium reabsorption, and DCT2 expressing genes involved in calcium reabsorption and electrogenic sodium channel (ENaC). Four days of K restriction switched the DCT from a K-wasting state to K-sparing state, shown by reduction of gENaC ( Scnn1g) and Kallikrein ( Klk1) expression. Furthermore, K restriction decreased the expression of the calcium-handling genes Slc8a1, Calb and Vdr. When prolonged, K restriction led to increases in NCC, reduction in ENaC cleavage, and elongation of the DCT. It also led to calcium wasting (plasma iCa in NK, 1.38 ± 0.03, n=7; KD, 1.24 ± 0.01 mM, n=6) and reduction in calbindin D-28k protein.Our results suggest that DCT1 and DCT2 both express NCC, but have distinct transcriptomic signatures with unique roles in magnesium and calcium transport, respectively. Dietary K restriction reprograms DCT2 cells to be more like DCT1 cells, thereby maintaining K balance but contributing to calcium wasting as a complication.

NIH DK51496, NIH DK054983, VA 1I01BX002228, LeDucq Fondation

This is the full abstract presented at the American Physiology Summit 2023 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.
Class participation correlates with academic performance in a Biochemistry and Metabolism course for first-year veterinary school students
Authors: Schonhoff Christopher , Cardamone Carie
Published: May 2023

The objective of the current study was to investigate whether class participation correlates with academic performance in a Biochemistry and Metabolism Course for first-year veterinary school students. Veterinary Biochemistry and Metabolism is a required course for first-year veterinary students at the Cummings School of Veterinary Medicine at Tufts University. The course is a large lecture course with approximately 100 students enrolled each year. Topics covered in the course include the metabolism of carbohydrates, nucleic acids, lipids, proteins, vitamins, and microminerals. In the fall of 2021, students had three options for lecture attendance. Students could attend in person, could listen to lectures streamed live, or could watch lectures at a later time since class sessions were all recorded. To increase engagement in the course, students receive Poll Everywhere questions during most of the lectures in this course. These questions were mainly in multiple-choice format and delivered to students at various times (beginning, middle, and end) during the class. Students who earned A, B, or C grades were compared with how often those cohorts participated in the Poll Everywhere questions. The results indicate that students who earned an A in the course have statistically significant higher participation in Poll Everywhere questions when compared to students who earned a B or C. The results do not distinguish between students who attended the lecture in person and those who watched the live stream since all those students could answer the Poll Everywhere questions during class time. The results demonstrate an association between class participation and academic performance. Namely, higher involvement as measured by answering Poll Everywhere question participation increases the likelihood of getting an A. Many professional schools (medical, dental, and veterinary) routinely record most lectures and do not require attendance. While lecture recordings may provide a valuable study tool for students, these results suggest that students who do not actively engage with class material miss an opportunity to maximize learning.

No funding to disclose

This is the full abstract presented at the American Physiology Summit 2023 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.
Acute Effect of Intermittent Hypoxia on Peripheral Vascular Function in Older Adults
Authors: Stray-Gundersen Sten , Wojan Frank , Tanaka Hirofumi , Lalande Sophie
Published: May 2023

Aging is associated with vascular endothelial dysfunction observed through a progressive loss of flow-mediated dilation, which is partly caused by a decreased nitric oxide bioavailability. Continuous exposure to hypoxia, achieved by breathing low levels of oxygen, stimulates nitric oxide production and induces peripheral vasodilation. Intermittent hypoxia, consisting of alternating short bouts of breathing hypoxic and normoxic air, triggers similar physiological responses to chronic hypoxia, but without the detrimental effects often associated with longer hypoxic exposure. The aim of this randomized crossover trial was to determine whether intermittent hypoxia induces brachial artery vasodilation and acutely improves flow-mediated dilation in older adults. Eleven apparently healthy older adults (six women, age: 57±7 years, body mass index: 24.5±3.5 kg/m2) visited the laboratory on two separate occasions. Endothelium-dependent vasodilation was assessed by brachial artery flow-mediated dilation using a semiautomated diagnostic ultrasound system before and 15 minutes after exposure to either intermittent hypoxia (IH) or intermittent normoxia (IN). Intermittent hypoxia consisted of eight 4-min hypoxic cycles at a targeted oxygen saturation of 80% interspersed with breathing room air to resaturation. Air was made hypoxic by titrating nitrogen into a breathing circuit. Intermittent normoxia consisted of eight 4-min normoxic cycles separated by one minute of breathing room air. Hemodynamics, oxygen saturation, and pulmonary gas exchange were continuously assessed during both conditions. By design, intermittent hypoxia resulted in an oxygen saturation of 81±1%, corresponding to an oxygen concentration of 11.4±0.6%. Exposure to intermittent hypoxia, but not intermittent normoxia, elicited a brachial artery vasodilation (IH: 3.61±0.49 to 3.73±0.48 vs. IN: 3.60±0.51 to 3.55±0.50 mm, p=0.01). Brachial artery flow-mediated dilation was not acutely affected by intermittent hypoxia or intermittent normoxia (IH: 5.4±2.0 to 5.5±2.4% vs. IN: 4.8±1.3 to 4.7±2.3%, p=0.17). Intermittent hypoxia did not affect mean arterial pressure (91±6 vs. 92±7 mmHg, p=0.56) but increased heart rate when compared to intermittent normoxia (61±9 vs. 55±9 bpm, p<0.01). In conclusion, exposure to intermittent hypoxia triggered a brachial artery vasodilation but did not immediately affect endothelium-dependent vasodilation in older adults. Repeated exposure to intermittent hypoxia may be necessary to improve endothelial function in this population.

This is the full abstract presented at the American Physiology Summit 2023 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.
Finnish Sauna Bathing and Vascular Health of Adults with Coronary Artery Disease: a Randomized Controlled Trial
Authors: Debray Amélie , Gravel Hugo , Garceau Laurence , Bartlett Audrey-Ann , Chaseling Georgia , Ravanelli Nicholas , Barry Hadiatou , Behzadi Parya , Desrosiers-Gagnon Charles , Neagoe Paul-Eduard , Sirois Martin , Nigam Anil , Gagnon Daniel
Published: May 2023

BACKGROUND: Regular Finnish sauna use has been associated with a reduced risk of cardiovascular mortality. However, physiological mechanisms underlying this association remain unknown. Other forms of heat therapy have been shown to improve markers of vascular health in healthy young adults, middle-aged adults with cardiovascular risk factors, and older adults with chronic heart failure. It is unknown if Finnish sauna use elicits similar adaptations. HYPOTHESIS: This study determined if Finnish sauna bathing improves markers of vascular health in adults with coronary artery disease (CAD). We tested the primary hypothesis that 8 weeks of Finish sauna bathing improves peripheral endothelial function. Secondary hypotheses were that Finish sauna bathing improves peripheral microvascular function, central arterial stiffness and blood pressure. METHODS: Forty-one adults (62 ± 6 years, 29.0 ± 4.3 kg/m2, 33 men/8 women) with stable CAD and naïve to heat therapy were randomized to 8 weeks of Finnish sauna use (n=21, 4 sessions/week, 20-30 min/session) or control intervention (lifestyle maintenance, n=20). Peripheral endothelial function (brachial artery flow-mediated dilation, FMD), central arterial stiffness (carotid-femoral pulse wave velocity), total (area under the curve) and peak post-occlusion forearm reactive hyperemia, and blood pressure (automated auscultation) were measured before and after the intervention. RESULTS: Brachial artery FMD changed from 4.09 ± 2.05% to 4.24 ± 2.70% in response to sauna bathing and from 4.00 ± 2.02% to 4.10 ± 2.10% in response to the control intervention (p for interaction = 0.95). The change in central arterial stiffness (p for interaction = 0.82), total reactive hyperemia (p for interaction = 0.07), systolic (p for interaction = 0.95) and diastolic (p for interaction = 0.29) blood pressure also did not differ between interventions. The change in peak reactive hyperemia differed between interventions (p for interaction = 0.05) due to a slight decrease in response to sauna bathing (3.03 ± 1.42 to 2.75 ± 1.18 ml/min/mmHg, p=0.76) relative to a slight increase in response to control (2.78 ± 0.98 to 3.24 ± 1.00 ml/min/mmHg, p=0.05). CONCLUSION: These results demonstrate that 4 sessions of Finnish sauna bathing per week for 8 weeks does not improve markers of vascular health in older adults with stable CAD.

Heart and Stroke Foundation of Canada, Fonds de Recherche du Québec – Santé

This is the full abstract presented at the American Physiology Summit 2023 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.
Effects of Neuromuscular Electrical Stimulation on Fasting Blood Glucose
Authors: Bajpeyi Sudip , Apaflo Jehu , Narvaez Gabriel , Labadah Joshua , Mossayebi Ali , Rocha Victoria , Jung Hyejin , Wagler Amy , Thyfault John , McAinch Andrew
Published: May 2023

Muscle contraction during physical activity improves glucose metabolism and glycemic control by facilitating muscle glucose uptake and utilization. Neuromuscular electrical stimulation (NMES) is an involuntary alternative mode of muscle contraction and is widely applicable and suitable for individuals with sedentary lifestyle including people with physical functional limitations and other mobility impairments. Use of NMES has the potential to improve metabolic health analogous to voluntary exercise. Purpose: To determine the acute effect of 30 mins of NMES on energy metabolism and fasting blood glucose level. Methods: Fifteen participants without diabetes participated in the study (Males: 6; Females: 9; Age: 33.80 ± 12.99 years; BMI: 32.59 ± 9.17 kg/m2). Each participant underwent 30 mins of cyclical NMES on the quadricep muscles of both legs while lying supine on a bed. NMES was applied at a frequency of 50Hz with a pulse width of 300μs up to maximum tolerable intensity. Blood glucose and lactate levels were determined at baseline and at 5 mins intervals during the stimulation. Energy expenditure and substrate utilization were measured at baseline and monitored continuously during the NMES via indirect calorimetry. The experimental procedure was performed in a fasting condition and was directly preceded by a day of dietary control. Results: A decreasing blood glucose effect of NMES was observed between baseline glucose level (95.94 ± 7.81 mg/dL) and after 25 mins (92.85 ± 8.82 mg/dL) and 30 mins (91.79 ± 9.00 mg/dL) of NMES (p<0.05). Average energy expenditure rate during the 30min of NMES (19.37 ± 4.49 Kcal/kg/day) was relatively higher than that of the resting baseline rate (19.24 ± 3.57 Kcal/kg/day) (p<0.05). Blood lactate level and respiratory exchange ratio (substrate utilization) however, remained unaffected throughout the experimental procedure. Conclusion: Neuromuscular electrical stimulation is effective in decreasing blood glucose level and hence could serve as a beneficial intervention for blood glucose management.

Supported by NIH Grant R01 DK132430

This is the full abstract presented at the American Physiology Summit 2023 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.
Placental-derived exosomal miR-125b disrupts maternal endothelial function in preeclampsia
Authors: Huang haiqin , Liu Xinlu , Li Qinghua , Su Hang , Meng Yuhan , Yang Weiwei
Published: May 2023

Preeclampsia (PE) is an elusive life-threatening complication of pregnancy, and maternal endothelial dysfunction induced by components from the impaired placenta is a key hallmark of PE. Placenta-derived exosomes in maternal circulation has been reported with increased risk of PE, however, whether exosomes impaired endothelial cell function remains to be determined. We hypothesized that placental exosomes from preeclamptic patients disrupt endothelial function. We observed that placenta derived serum exosomes from preeclamtpic patients (PE-exo) significantly reduced VE-cadherin expression in primary cultured human umbilical vein endothelial cells (HUVECs), thus resulting in increased endothelial permeability. Realtime qPCR results indicated more miR‑125b in PE-exo. Moreover, we identified that VE-cadherin was a direct target of exosomal miR-125b in HUVECs. miR-125b could partly mediates the adverse effect of PE-exo on endothelial functions. Our findings suggest that miR-125b derived from placental exosomes is involved in the progression of PE and could be a promising therapeutic target for PE.

This work was funded by grants from the Natural Science Foundation of Shandong Province (ZR2022MH195, ZR2019BH037), Graduate Student Research Grant from Weifang Medical University

This is the full abstract presented at the American Physiology Summit 2023 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.
Allergen-stimulated secretion of DNA fragments by the airway epithelium enhances type 2 immune responses
Authors: Srisomboon Yotesawee , Iijima Koji , Colwell Mathia , Maniak Peter , Faulk Chris , Kita Hirohito , O'Grady Scott
Published: May 2023

Exposure of human bronchial epithelial cells (hBECs) and mouse airways to allergens from the fungus Alternaria alternata triggers the release of alarmin signaling molecules including ATP, IL-33 and DNA fragments. The goal of this study was to determine the mechanisms that regulate release of genomic DNA fragments and how extracellular DNA (eDNA) contributes to type 2 immunity. Treatment of hBECs with Alternaria extract induces oxidative stress, which leads to ATP release and uptake of Ca2+ following activation of P2X receptors. DNA release was dependent on a sustained increase in intracellular [Ca2+], which stimulates cleavage of caspase 3 by the proprotein convertase enzyme furin, resulting in activation of caspase 3 and ultimately nuclear DNA fragmentation as shown in comet assays. Some of the fragmented DNA was released into the media under conditions where barrier function of the epithelium was maintained, and nuclear and plasma membranes remained intact. Alternaria-induced DNA release was detected within 30 minutes following exposure, reached its peak at 4 hours and ceased after 12 hours. Pretreatment of hBECs with a calpain inhibitor resulted in continued DNA release and loss of cell viability by 24 hours. This result suggested that calpain activity contributed to termination of Alternaria-evoked DNA release. In mice, intranasal administration of Alternaria extract produced release of DNA fragments into bronchoalveolar lavage (BAL) fluid over a similar time course as observed in hBECs. In caspase 3 deficient mice however, DNA release into BAL fluid was significantly reduced. Furthermore, Alternaria-induced type 2 immune responses were suppressed following pretreatment with a DNA scavenger. Conversely, intranasal administration of mouse genomic DNA with Alternaria amplified IL-5 and IL-13 secretion into BAL fluid while DNA alone had no effect. These findings indicate that DNA release from the airway epithelium is a regulated process involving noncanonical activation of caspase 3 to produce DNA fragmentation and calpain activity, which appears to be essential for the termination of DNA release. Moreover in airways, eDNA appears to function as a secondary alarmin that acts on immune cells to enhance type 2 immunity.

This work was supported by grants from the NIH (AI128729 and AI169530) to HK and SMO.

This is the full abstract presented at the American Physiology Summit 2023 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 toolbox of strategies to improve test-taking skills: A comparison of student perceptions in physiology coursework
Authors: Metz Cynthia , Metz Cynthia , Metz Michael
Published: May 2023

Recent changes in the Medical and Dental National Board Examination structures have renewed interest in the development of test-taking strategies for professional students. It is often assumed that these students have developed proficient test-taking skills and metacognitive abilities prior to admittance. However, the assessments in these programs and for national licensure require a high level of reasoning and integration that may necessitate additional training.The goal of this project was to present a toolbox of strategies that provided opportunities to: contemplate new test-taking strategies, observe modeling of appropriate skills, participate in formative and team-based activities to practice skills, and reflect on the use of the strategies following summative course assessments. It was hypothesized that the implementation of the immersive test-taking strategies program would improve student perceptions of their abilities and confidence regarding national board preparation.Dental students engage in physiology coursework in the first two semesters of the curriculum, which likely serves as a crucial time for the refinement of appropriate test-taking strategies. For this study, a “toolbox” of four methods was implemented with 120 students enrolled in a first-year Dental Physiology course. These included: 1. An introductory video that provided students with ten tips for approaching high-level exam questions 2. Problem solution videos interspersed with class practice problems to walk students through rationales 3. Collaborative group assessments in which students implemented the strategies in teams to prepare for exams and 4. Unit exam debriefings to review the question rationales.While all methods were positively reviewed on surveys, students indicated that the problem solution videos and the collaborative group assessments were more helpful and improved their test-taking skills significantly more than the other strategies (P<0.05, one-way ANOVA and Bonferroni post hoc test). On average, students rated their test-taking skills when entering the program at a 3.71 on a 5-point Likert scale. At the conclusion of the semester, they indicated that they had developed strong test-taking strategies for the course (average of 4.21) and felt more prepared to complete the National Board Dental Examination (average of 4.48)These results suggest that a multi-pronged approach, with frequent opportunities to practice test-taking strategies, can improve student perceptions of their ability to master high-level and integrated questions. Future studies will examine correlations between student perceptions and actual exam performance, and differences between medical and dental student populations.

This is the full abstract presented at the American Physiology Summit 2023 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.
Automation of the neonate autoresuscitation assay and its analysis
Authors: Ward Christopher , Patel Dipak , Ruiz Brandon , Garcia Acosta Mariana , Memos Nicoletta , Lusk Savannah , Aissi Eunice , Ray Russell
Published: May 2023

Background: Sudden Infant Death Syndrome is thought to partly result from unseen brain abnormalities affecting cardio-respiratory function, but for which no clear genetic or environmental mechanisms are known. Mouse genetic and exposure models present an opportunity to uncover molecular and environmental mechanisms. However, measuring cardio-respiratory function in neonate mice is expensive, difficult, and inefficient. One major challenge is the time needed to carry out such measurements. The neonate autoresuscitation assay, consisting of repeated anoxic exposures followed by recovery, requires the full attention of an observer for the multi-hour duration of a single-subject assay, limiting throughput. To address this, we developed a closed-loop feature detection platform for automated neonate cardio-respiratory measurements. Methods: Our platform design consists of: 1) a pneumotachograph face-mask for precise respiratory measurements. 2) a micro-controller automated bell-housing gas switching system for rapid induction of respiratory challenges. 3) a micro-computer-based data-acquisition system with real-time feature detection and outputs for controlling gas exposure. 4) a data analysis suite that assists with recordkeeping and provides a facile method to extract key outcome measures. Results: Gas challenges are administered via the rotating bell housing system. A python program detects waveform features in real-time, such as apnea and bradycardia. Upon apnea detection, the system switches to a rescue gas. Resumption of normal breathing and heart rate can also be detected and incorporated into criteria for automated initiation of the next anoxic exposure trial. Data is stored for later offline automated analysis using the data analysis suite. Conclusions: The system offers a relatively inexpensive approach for automated high throughput neonate cardio-respiratory assessment. The improvements permitting increased throughput and reduced variation in experimental parameters makes the system suitable for screening of genetic and exposure risks as well as potential therapeutics for Sudden Infant Death Syndrome.

NIH: R01 HL130249, UM1HG006348, R01DK114356. BCM KOMP2 Precision Disease Modeling Pilot Award, BCM McNair Scholar Program, March of Dimes Basil O’Connor Research Award, Parker B. Francis Fellowship, CJ Foundation for SIDS

This is the full abstract presented at the American Physiology Summit 2023 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.
Chronic hyperoxia augments the hypoxic ventilatory response in adult rats
Authors: Danielson Matthew , Bavis Ryan
Published: May 2023

Chronic hyperoxia during postnatal development causes long-lasting attenuation of the hypoxic ventilatory response (HVR) in rats, but similar exposures during adulthood do not attenuate the HVR (Ling et al. J Physiol 405: 561-571, 1996). However, the HVR has not been assessed in adult-exposed rats immediately after chronic hyperoxia (i.e., without several months of recovery in room air). This is important since chronic hyperoxia depresses breathing and blunts the HVR in newborn rats, and only some of these effects persist after return to room air. Accordingly, adult rats were studied after 4 and 14 days of exposure to either 60% O2 (Hyperoxia) or 21% O2 (Control). Ventilation was measured by whole-body plethysmography; metabolic O2 consumption and CO2 production were also measured in a subset of rats. Normoxic ventilation was unchanged, but Hyperoxia rats exhibited a slight increase in their acute HVR after both durations of chronic hyperoxia. Overall, minute ventilation was approximately 10% greater in Hyperoxia rats while breathing 12% O2 and 10% O2 than in Control rats; this effect did not differ significantly between female and male rats. The HVR was also enhanced after 4 days of hyperoxia after controlling for metabolic rate, but the results were less clear after 14 days. After the 14-day exposure, the HVR tended to be enhanced when tested at 12% O2 but not at 10% O2. These data demonstrate that chronic hyperoxia has different effects on the control of breathing in neonatal and adult rats when assessed immediately after the exposure.

Supported by NIH grant P20 GM-103423 (Maine INBRE).

This is the full abstract presented at the American Physiology Summit 2023 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.
Angiotensin II type 2 receptor-mediated dilation is greater in the cutaneous microvasculature of premenopausal women compared to men
Authors: Schwartz Kelsey , Lang James , Stanhewicz Anna
Published: May 2023

Sex differences in the activation of the renin-angiotensin system (RAS) likely contribute to differences in cardiovascular outcomes in premenopausal women compared to age-matched men. It is established that women have a reduced activation of the vasoconstrictor angiotensin II – angiotensin II type 1 receptor (AT1R) pathway. Emerging evidence suggests that this may be mediated by a shift toward the more recently described vasodilatory RAS, including increased sensitivity of the vasodilatory angiotensin II type 2 receptor (AT2R). However, few in vivo studies have directly examined sex differences in AT2R-mediated dilation, or the balance between AT1R- and AT2R-mediated vascular responses in humans. Using the cutaneous microcirculation as a model, we hypothesized that AT2R-mediated dilation would be greater in premenopausal women compared to men, and that AT1R-blockade would augment AT2R-mediated dilation to a greater extent in men than in women. Eight healthy women (22±3 years) and 11 healthy men (23±5 years) participated in 1 experimental visit. Two intradermal microdialysis fibers were placed in the skin of the ventral forearm for graded infusions of either compound 21 (C21, AT2R agonist; 10-12 - 10-3 mol/L) alone or C21 + 43 μmol/L losartan (AT1R antagonist). Red blood cell flux was measured over each microdialysis site by laser-Doppler flowmetry. Cutaneous vascular conductance was calculated (CVC=doppler flux/mean arterial pressure) and normalized to maximum (%CVCmax; 28mM SNP+43°C). Women had a greater peak vasodilation response to C21 compared to men (27.2±5.7 versus 18.2±2.7 %CVCmax; p=0.03). AT1R-inhibition augmented peak C21-mediated dilation in men (31.3±4.5 versus 18.2±2.7 %CVCmax; p=0.009) but had no effect in women (24.5±6.5 versus 27.2±5.7 %CVCmax; p=0.34). These data suggest that premenopausal women have a greater AT2R-mediated vasodilation response than men, and that AT1R activation inhibits AT2R-mediated dilation in men, but not in women.

This study is supported by National Heart, Lung, and Blood Institute Grant R00HL138133. Clinicaltrials.gov identifier: NCT05576155

This is the full abstract presented at the American Physiology Summit 2023 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.
Microvascular Health is Reduced in Frequent Cannabis Users
Authors: Simovic Tijana , Mattheson Chloe , Cobb Kolton , Heefner Allison , Thode Christopher , Garten Ryan , Rodriguez-Miguelez Paula
Published: May 2023

BACKGROUND: Microvascular dysfunction is a marker of endothelial vascular damage and is considered one of the earliest indicators of cardiovascular disease (CVD) development. Frequent cannabis use has been previously linked to increased CVD risk. However, whether microvascular health is impacted by cannabis use in otherwise healthy young adults has not been explored yet. PURPOSE: The purpose of this study was to investigate the impact of frequent cannabis usage on microvascular health in young healthy adults. METHODS: Thirteen frequent cannabis users (CU, 5 males and 8 females; age:23±3 yo; used cannabis 2.5±2 days/week) and thirteen demographical matched never users (NU, 5 males and 8 females; age:22±1 yo) completed a comprehensive assessment of microvascular function. Microvascular health was assessed using Laser Doppler Imaging coupled with Post Occlusive Reactive Hyperemia (PORH), to evaluate overall microvascular function, and Local Thermal Hyperemia (LTH) to evaluate neurogenic and endothelial mechanisms of vascular function. Blood flow was calculated as cutaneous vascular conductance, considering red blood cell flux and mean arterial blood pressure. RESULTS: Cannabis users exhibited significantly ( p=0.01) lower microvascular function when compared to never users (PORH, CU: 0.68±0.18 vs. NU: 0.85±0.14 mmHg/PU). Of note, microvascular function was significantly ( p=0.03) reduced in those that use cannabis more than 2.5 days/week (n=5; 0.55±0.10) when compared to those who used it less frequently (n=8; 0.76±0.18 mmHg/PU). In addition, neurogenic mechanisms (CU:1.31±0.57 vs. NU: 1.89±0.48 mmHg/PU; p=0.009) and endothelial mechanisms (CU: 1.61±0.44 vs. NU: 1.96±0.35 mmHg/PU; p=0.03) were significantly lower in cannabis users when compared to never users. CONCLUSIONS: Our results suggest that frequent cannabis users exhibit reduced microvascular health in comparison to never users, suggesting worse long-term CVD outcomes. Specifically, those that use cannabis more than 2 times per week exhibit lower microvascular function. In addition, cannabis use negatively impact neurogenic and endothelial microvascular mechanisms that warrant further investigation.

This is the full abstract presented at the American Physiology Summit 2023 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.
Nicotinamide adenine dinucleotide concentrations in a mouse model of Down Syndrome
Authors: Cooke Lauren , DeRuisseau Lara , Brandauer Josef
Published: May 2023

Individuals with Down Syndrome (DS) may experience impaired cardiac and skeletal muscle function, resulting in lower work and exercise capacity, lower blood pressure, and reduced cardiovascular responses.Nicotinamide adenine dinucleotide (NAD) is critical for maintaining mitochondrial function. It transfers electrons within cells, acting as a messenger between metabolism and cell signals. It is uncertain whether DS pathophysiology is caused by an imbalance of NAD and/or changes in mitochondrial activity. Our study analyzed the levels of NAD in the tissue of wild-type and Ts65Dn (a mouse model of DS) mice. We hypothesized that NAD levels are differentially regulated in WT and Ts65Dn mouse tissue.NAD concentration was analyzed using a kinematic fluorescence assay. We normalized NAD concentration based on the tissue mass of each aliquot and corrected for between-plate differences using internal control samples. We found significantly different NAD concentrations in the left ventricle of Ts65Dn mice (WT, 22.8±5.1 mmol/mg, TS65 Dn, 15.3±4.1 mmol/mg [mean±SD], p=0.003), and non-significant but reduced concentrations in skeletal muscle (quadriceps, tibialis anterior), and kidney tissues of Ts65Dn animals. Our findings suggest that, based on our findings in a mouse model of DS, reduced NAD levels may be a part of the pathophysiology associated with DS. Characterizing this phenotype could lead to a better understanding of potential drug targets to alleviate the impaired cardiac and skeletal muscle function of DS, allowing for improved work and exercise capacity.

This work was supported by a Gettysburg College Professional Development Grant to JB. LD was supported by NIH grants 1R15 HD076379, 3R15 HD076379-S1, 3R15 HD076379-S2, and 1R21HD099573. Further funding was provided by the Cross-disciplinary science institute at Gettysburg College via the Dickson Fund; Kolbe Fund; Albaugh Fund in Chemistry; Alberte Fund in Biology; and the Cormack, Hendrickson, Peterson and Schweizer Funds in Physics.

This is the full abstract presented at the American Physiology Summit 2023 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.