Additional Content Research Articles

Preparation and performance study of waste plastic blended ultrafiltration membrane

Waste plastic packaging bags (rPVC) and waste milk tea straws (rPLA) were used as membrane materials to prepare ultrafiltration (UF) membranes by the non-solvent induced phase separation (NIPS) method. The study aimed to investigate the influence of various factors, including different rPVC contents (10 wt%-20 wt%), membrane fractions (rPVC/rPLA), additive fractions (Pluronic F-127/PVP-K30), and different additive contents (0.5 wt%-3.0 wt%), on the performance of the membranes. The permeability, morphology, hydrophilicity, chemical composition, thermal stability, and antifouling properties of the blended UF membranes were thoroughly investigated. The experimental results revealed that the presence of rPLA and Pluronic F-127 increased the porosity, water absorption, pore size, and hydrophilicity of the blended UF membranes. Furthermore, the introduction of rPLA enhanced the thermal stability of the blended UF membranes. Additionally, the incorporation of Pluronic F-127 further improved the overall performance of the blended UF membranes. Specifically, it was found that the blended UF membranes achieved a pure water flux (PWF) of 192.50 L·m−2·h−1, while maintaining a bovine serum albumin (BSA) rejection rate of 95.20%. These results were obtained using a content ratio of rPVC/rPLA (90/10) at 14 wt% and an additive content of Pluronic F-127 at 2.5 wt%. By comparing with the blended UF membranes without introducing additives into the casting solution, the roughness (Ra) was reduced by 40.3%, the water contact angle (WCA) was reduced by 7.5%, the flux recovery rate (FRR) was increased by 80.5%, and the fouling resistance was enhanced.

Comparative effectiveness of C3-Hydrocarbons and their mixtures on suppression of hydrogen-air explosions

The next-generation energy economy relies heavily on hydrogen. Handling hydrogen during production, storage, and transportation requires risk mitigation. In this regard, the application of halide-free additives is very crucial. The present study experimentally and theoretically investigates the individual and combined inhibiting effect of propane and propene on hydrogen-air explosions. The experiments are carried out at 298 K and 1 bar, with additives ranging from 0.5 to 5% for the individual and 1–2% each for the combined effect in the 20–50% hydrogen-air mixture. Experimentally, the additive content in the stoichiometric and rich mixture decreases the explosion pressure, maximum pressure rise (MPR) rate, laminar burning velocity (LBV), and flame temperature, while increasing minimum ignition energy. For instance, the addition of 2% propane in a 50% hydrogen-air mixture, reduces the MPR rate by 98%, whereas such an effect is observed with 2.5% propene. Theoretical study shows that 3% equivalent additive augments inhibiting reactions, countering the main flame-promoting reaction R1 (H + O2O + OH) and thereby reducing LBV. Due to its low activation energy, propene consumes the active radicals twice the rate of propane, while propane not only scavenges the active radicals but also promotes oxygen consumption in the prior phase of combustion, weakening flame propagation. Overall, this approach exhibits a significant step forward in harnessing the potential of hydrogen while mitigating the safety risks associated with its use.

Polymer-modified mortar flexibility of the masonry-concrete structure interface

High crack occurrences at the masonry-infilled wall partition-reinforced concrete structure interface is a problem that challenges the Brazilian construction process. Improving the mortar’s flexibility is suggested as a potential solution, but it's still not widely known. This paper evaluates industrialized mortar properties modified with four polymers and one plasticizer additive. The research methodology consisted of an experimental investigation related to the mortar properties using styrene-acrylic copolymer (SAE), polyvinyl acetate copolymer (PVAc), styrene-butadiene copolymer (SBR), white glue PVA (polyvinyl acetate), and a sulfated ethoxylated fatty alcohol salt plasticizer additive. The polymers were used in addition to (4%, 5% and 8%) and instead of (4% and 5%) the amount of water established by the manufacturer of the reference mortar, while the amount of additive used was 0.08%. The investigation characterization considered the fresh and hardened conditions, especially, the flexibility evaluation, and tests of elasticity modulus and transverse deformation were carried out, in addition to scanning electron microscopy (SEM). The results showed that there was an elasticity modulus reduction of all mixtures compared with the reference mortar without modification. The transverse deformation results range from a minimum of 0.23 mm (SBR) to a maximum of 0.94 mm (SAE). Regarding SEM, the tests with polymers have smoother and less porous surfaces. The mortar flexibility performance with different additive contents is the main contribution of this research.

Continuous preparation and antibacterial mechanisms of biodegradable polylactic acid/nano-zinc oxide/additives antibacterial non-wovens

Biodegradable polylactic acid (PLA)/nano‑zinc oxide (ZnO)/additives non-woven slices were prepared by melt blending method. The effects of antibacterial agent nano-ZnO, antioxidant pentaerythrityl tetrakis-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (1010), and chain extender multi-functional epoxy (ADR), on the melt flow rate, mechanical properties, thermal stabilities and micromorphology of the slices were investigated. The melt flow rate decreased from 26.94 g/10 min to 17.76 g/10 min, and the tensile strength increased from 10.518 MPa to 30.427 MPa with the increase of nano-ZnO and additives content. The slices were further spunbonded. The wettability and antibacterial properties of PLA/nano-ZnO/additives antibacterial non-wovens were studied, and the antibacterial action mechanism was clarified. The results showed that the biodegradable PLA/nano-ZnO/additives antibacterial non-wovens were prepared continuously successfully. The prepared non-woven fabrics exhibited good hydrophobicity and antibacterial properties. The mechanism study shows that zinc ion produced by nano-ZnO and photocatalytic reaction make the fabrics have good antibacterial activity at low nano-ZnO content. When nano-ZnO concentration reaches 1.5 wt%, the antibacterial rate against Escherichia coli and Staphylococcus aureus reaches 98.52 % and 98.13 %, respectively.

Determination of Erucamide Slip Additive in Polypropylene Masterbatch: Comparison of Soxhlet and Dissolution-Precipitation Method

Erucamide is a long-chain carboxylic acid amide used as a slip agent in plastic films. In this research, the slip additive in polypropylene masterbatch with 6% erucamide content was extracted by comparing two methods which are dissolution-precipitation and the Soxhlet method. The variant of sonication times in the dissolution-precipitation method and extractor-solvents in the Soxhlet method were done to determine the optimum parameter in each method. The examination of slip additive content in each extraction method used the KBr Disk-FTIR and the weight loss of sample analysis. The form of the sample, which was in the granule and powder form was also studied. Based on the result, the dissolution-precipitation method with 3 minutes of sonication times and the use of ethyl acetate as extractor solvent in the Soxhlet method gave a closer result for additive content in the masterbatch. The powder form of the sample also gave better results than the granule form for the extraction of erucamide. The Soxhlet method in the powder form showed comparable results with the dissolution-precipitation method by KBr Disk-FTIR analysis and higher results by weight loss analysis. By comparing the two methods of extraction, the Soxhlet method showed more robustness and efficiency for extraction of erucamide additive in polypropylene masterbatch than the dissolution-precipitation method.

Numerical and experimental investigations of micro Al particle additive on the performances of HTPB hybrid rocket motors

The hybrid rocket motor (HRM) emerges as a promising propulsion system offering thrust adjustment at a low cost. Prior research has indicated that the inclusion of micro Al additives enhances HRM performance, yet a comprehensive investigation remains absent. Thus, this study aims to explore the impact of Al particle additive content and size variation on the characteristics of hybrid rocket motors (HRMs) through experiments and simulations. Firing tests are conducted on HRMs employing unadulterated HTPB, 38 % additive Al (2 μm), and 58 % Al (2 μm). Experimental findings reveal enhancements of 12.6 % and 33.9 % in regression rate, and 2.5 % and 8.0 % in specific impulse for the 38 % Al and 58 % Al fuel configurations, respectively, compared to the base case. Subsequently, a numerical two-phase combustion model is built to analyze the inner flow field characteristics. The high consistency between experimental and simulation results validates the efficacy of the numerical approach employed. Following this, a series of simulations covering Al content ranging from 0 % to 58 % and Al particle sizes from 0.4 μm to 75 μm is conducted. Simulation outcomes indicate that specific impulse and combustion efficiency enhancements correlate with the increase in Al mass fraction for particles with diameters under 35 μm. However, high Al content proves detrimental to specific impulse and combustion efficiency when particle diameter exceeds 35 μm. Additionally, regression rate and thrust demonstrate an increase with Al content, albeit the rate of increment diminishes with larger Al particles. This study comprehensively examines the influence of Al particle addition on HRM performance and elucidates the underlying mechanisms, thereby offering insights into HRM design and manufacture.

Abstract PS02-08: The Effect of a Digital Health Coaching Program on Patient Reported Outcomes of Women with Breast Cancer

Abstract Background Understanding the impact of a digital health coaching (DHC) program on patient-reported outcomes in women with breast cancer is imperative as web-based platforms and mobile phone applications to address health care needs flood the marketplace. This study evaluated the effect of a DHC program on patient-reported outcomes, including global health (primary outcome), symptom burden, quality of life, healthcare utilization, and financial toxicity among women undergoing active treatment for breast cancer. Methods English-speaking adult women undergoing active treatment for breast cancer were randomized to receive usual care or a 6-month DHC program, consisting of weekly telephone calls from a Health Advisor, unlimited patient-initiated communication via phone, text, or email, and digital delivery of additional health-behavior content. Patient-reported outcomes (PROs) were collected using validated measures at baseline, and 1, 3, and 6 months. Summary statistics were used to describe participant characteristics. Linear mixed models were used to assess the effect of the intervention on outcomes. Results Participants (n=254, planned enrollment=440) were enrolled from August 2019 to December 2022 and randomized equally to the control and intervention groups (n=127 each). Demographic data are presented in Table 1. Participants had a mean age of 48 (SD =10.15) years; 74% were White; 19.7% were Hispanic. In both groups, several PRO scores changed over time with some improving (quality of life and symptom severity) and others worsening (symptom interference and financial toxicity) compared to baseline (time effects). Of those enrolled in the intervention group 69% were retained in the DHC program, with an overall average of 4.6 months of engagement for all participants. There were no significant group (intervention versus control) effects or group by time interaction effects observed. Trends within and between groups are presented in Table 2. Though not statistically significant, there were fewer ER visits in the intervention group at each timepoint. Conclusions: While differential improvements in the DHC group were not observed, interesting trends in PROs over the 6-month enrollment period were observed in both groups. Participants reported improvements in quality of life and worsening of financial toxicity. Interestingly, slight improvements in symptom severity over time were observed in both groups while symptom interference worsened. Potential reasons for failure to detect a treatment effect for DHC may include ineffectiveness of DHC on the selected outcomes, the intervention not being strong enough as currently delivered to detect a treatment effect, varying uptake of DHC in the intervention group, heterogeneity of the sample, or the study being underpowered due to COVID restrictions affecting enrollment. Table 1. Demographic and clinical characteristics of the study population (n = 254) Table 2. Trends in Patient Reported Outcomes and Healthcare Utilization Citation Format: Meagan Whisenant, Eileen Hacker, Loretta Williams, Joyce Dains, Bryan Fellman, Trinity Isaac, Valerie Shelton, Austin Barr, Carolyn Harty, Mazi Rasulnia, Kelly Brassil. The Effect of a Digital Health Coaching Program on Patient Reported Outcomes of Women with Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS02-08.

Collaborative Critical Thinking Problem Sets Enhance Student Perceived Learning and Promote Student Practice Outside of the Classroom

Collaborative learning and peer-to-peer teaching activities can greatly enhance student learning and engagement in the classroom. This work evaluates the implementation of an additional required class period dedicated to collaborative problem solving activities. A two-semester integrative upper-level anatomy and physiology course (Human Anatomy and Physiology 1 and 2) was revised for the 2022-2023 academic year from a 2 x 75-minute weekly schedule to a 3 x 75-minute weekly schedule to facilitate an extra class period each Friday dedicated to graded collaborative critical thinking worksheets called Problem Sets. Two Friday Problem Set sessions were scheduled for each unit, resulting in an additional 150 minutes of faculty-student contact time per unit and 8 Problem Sets per semester, totalling 16 Problem Sets for the year-long course. Students were encouraged to work in groups on these questions which integrated the previous two class period’s content and additional previous course content, as applicable. Questions in each Problem Set targeted concepts at the Apply, Analyze, or Evaluate learning levels of the Modified Bloom's Taxonomy. Each student turned in their own answer page for an individual grade, serving as a formative assessment. The Problem Set worksheets also included three reflective questions asking the student to note which classmates they worked with, how well they felt they understood the material, and what they did outside of class to prepare for the Problem Set session. The cohort of students in this study was 14 students/semester. In 16/16 Problem Sets, 100% of the students responded to an open-ended question indicating that they completed the Problems Sets with classmates and identified their specific collaborators. In 13/16 Problem Sets, students’ responses to the multiple choice reflective question, “After completing these questions with my classmates I feel…”, 85% of the students responded “...like I understand the material better,” and the remaining 15% responded “...about the same.” In the other 3/16 Problem Sets, only 64% of the students responded “...like I understand the material better.” This indicates that some Problem Sets were more effective than others in assisting students with perceived learning and understanding of the content. Notably, as the semester progressed, students increased their response details to the open-ended question, “How do you prepare for these Friday sessions?”. At the beginning of the semester many students left the question blank or wrote “nothing”, but beginning with Problem Set 4 students started to list specific things they did outside of class to prepare for these sessions, such as “reviewing course notes” or “redrawing pathways and figures” or “completing practice problems in the textbook.” By Problem Set 7 more than 80% of students were sharing details on how they increased their study time outside of class to prepare for Problem Sets. These responses highlight the students’ increased utilization of metacognitive strategies that lead to success (i.e. spending more time outside of class preparing for in class activities) and the benefit of these activities on their learning and understanding of the course material. Collectively, these qualitative data support the continued use of Problem Sets in this integrative year-long anatomy and physiology course. none. 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.

Defining cardiac stability during Langendorff perfusion

The Langendorff heart preparation is a valuable ex vivo technique for studying cardiac electrophysiology. For the past century it has been used in toxicology studies, drug testing, and disease modeling and has contributed significantly to understanding cardiac physiology, development, and pathological states. This study aimed to investigate the stability and reproducibility of the modern Langendorff heart preparation under various experimental conditions and to establish cardiac metric standards with corresponding exclusion criteria. Isolated hearts were extracted from adult Sprague Dawley rats and retrograde perfused with a modified Krebs-Henseleit buffer. A cohort of isolated hearts were used to establish a control baseline of multiple physiological parameters measured over time (e.g., electrocardiogram, flow rate, electrophysiology, electrical and calcium dynamics). These control baseline values were then compared to hearts exposed to the most common media additives in Langendorff studies (e.g., blebbistatin(−/−), bovine serum albumin, and voltage and calcium indicator dye). Over a three-hour period, cardiac metrics were monitored in stable Langendorff-perfused hearts. The addition of blebbistatin, DMSO or dyes did not change EP or ECG measurements as compared to control baseline. The most significant drift in all the EP values was ventricular effective refractory period (VERP). With or without blebbistatin, VERP increased from 40 to 60ms over the course of three hours. In that time heart rate and flow also decreased slightly. Blebbistatin was associated with an increased action potential duration but did not alter calcium transient duration. It was also observed that 1% circulating bovine serum albumin quenched the rh237 voltage dye signal 80% as measured by signal to noise. Constant pressure Langendorff-perfusion with a crystalloid buffer provides a reliable and reproducible model for cardiac electrophysiology research with a few caveats. The total length of study should be carefully considered to account for adaptations in cardiac physiology during longer perfusion times. As an excitation-contraction uncoupler, blebbistatin reduces motion artifact but delays action potential duration. Although BSA is used to minimize cardiac edema, it interferes with membrane bound voltage dyes. This study sets physiological parameters as a useful guide for future cardiac studies that use the isolated heart as a research model. American Physiological Society, R01HD108839 to N.G.P. 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.

Gut microbiome alterations in Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) suggests variation in the gut-brain axis and gut metabolic potential

PANDAS, or Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections is a form of Children’s Post infectious Autoimmune Encephalopathy (CPAE), a neuropsychiatric condition characterized by the abrupt onset of diverse neuropsychiatric manifestations following streptococcal infection. It is an increasingly recognized neuropsychiatric disorder that affects a subset of children whose underlying etiology remains unclear. Gut microbiome plays a crucial role in its host brain development and is implicated throughout the life in neurobehavior and neurological disorders. Emerging evidence suggest gut dysbiosis resulting in altered intestinal flora can impair gut barrier and increase leakiness in the blood-brain barrier leading to inflammation. We aimed to investigate if the microbiome is altered in pediatric patients with PANDAS. Stool (n=19), oral (n=20) and nasal swabs (n=18) were collected from patients diagnosed with PANDAS or healthy controls (HC) and used for 16S analysis. 13 stool samples (7 HC and 6 PANDAS) samples were further used for shogun metagenomics and 17 for untargeted metabolomics (8 HC and 9 PANDAS). 16S rRNA gene sequencing identified significant difference in microbial α diversity, with lower Shannon H’ in PANDAS compared to HC (Welch’s t-test t(16.95)=-2.6, p=0.02), and in β-diversity (PERMANOVA R2=0.08 p=0.04) between PANDAS and HC fecal but not throat and nasal samples. Shotgun metagenomics identified a significant reduction in gene diversity (Welch’s t-test t(9.9)=-3.06, p=0.01) and changes in various KEGG ortholog modules involved in gut metabolism and gut-brain axis. Significant differences were also detected in metabolite composition (PERMANOVA R2=0.10, p=0.02). We also identified a set of microbial groups and metabolites enriched or depleted in CPAE patients, involved in different aspects of host physiology and gut metabolism. Our results show that PANDAS patients have an altered gut microbial community, which may exacerbate their behavioral symptoms and it should be taken into consideration in unveiling the complex pathogenesis and selection of treatment options. Arizona Department of Health Services RFGA2022-010-23 (PK) and ADHS17-00007403 (SR, MD); The Alex Manfull Fund (PK). 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.

ApoHemoglobin-Haptoglobin protects from hemoglobin induced nephropathy

Hemolysis, the process by which red blood cell membranes rupture, releasing hemoglobin (Hb), is typically managed in mammalian organisms by intrinsic proteins such as hemopexin (Hpx) and haptoglobin (Hp). Their presence in response to circulating heme and hemoglobin within the bloodstream aids in mitigating the potential adverse effects of minor hemolysis. However, their concentrations in the plasma are very limited, and, in instances of severe hemolysis, they are unable to protect against multi-organ toxicity due to the Hb and heme leakage and the generation of reactive oxygen species, resulting in cellular and tissue damage. In response to this challenge, our research group has developed a novel dual scavenger protein named ApoHemoglobin-Haptoglobin (ApoHb-Hp). This engineered protein is a protective mechanism by binding to free heme and Hb, thereby preventing tissue damage induced by Hb and heme. Previous studies have shown that ApoHb-Hp can reduce microvascular constriction and diminish the levels of inflammatory cytokines in critical organs, highlighting its potential as a therapeutic candidate. To further investigate the protective function of ApoHb-Hp, we focused on podocytes, specialized cells enveloping the capillaries of glomeruli and crucial in establishing the filtration barrier within the kidney. The dimerization of hemoglobin often disrupts this filtration barrier, causing detrimental effects on the glomerulus and its podocytes. In our study, we cultured podocytes in various environments, including a control group with human serum albumin, a group with hemoglobin, a group with ApoHb-Hp, and a combination group with both ApoHb-Hp and hemoglobin. The results demonstrated a significant reduction in the production of reactive oxygen species (ROS) in the ApoHb-Hp with Hb group, 264.6 AU ± 21.9, compared to the group exposed to Hb alone, 468.2 AU ± 50.2, illustrating the protective role of ApoHb-Hp. A decrease in ROS was consistent with percentage of cell viability, showing a significant decrease in cell viability for the Hb group, 55.1% ± 8.2, compared to the ApoHb-Hp group with Hb, 77.4% ± 9.8. Moreover, the percent of positive nephrin cells, the protein in charge of creating the filtration barrier in between podocyte processes, seem to be significantly decreased in the Hb group, 18.3% ± 4.5, compared to the ApoHb-Hp with Hb group, 29.6% ± 3.7. Lastly, there was an observed increase in the production of heme oxygenase 1 and nuclear factor erythroid 2 in the ApoHb-Hp with Hb group, which are crucial proteins in shielding cells against oxidative stress and toxicity. Both the control group and the ApoHb-Hp group displayed no significant differences in these results, underscoring the therapeutic's biocompatibility. This study highlights the toxic characteristics of Hb in kidney cells. It demonstrates how our ApoHb-Hp therapy may act as a protective mechanism in severe hemolysis, mitigating kidney injury by preserving cellular integrity and functionality. Title of the project: Bioengineering a Dual Function Protein Construct to Detoxify Heme and HemoglobinProject number: R01HL159862Title of the project: Bioengineering a novel therapeutic protein complex to minimize the effects of medical device induced hemolysis.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.

Preliminary analysis of the THRIVE clinical trial on the effect of resistance exercise on skeletal muscle bioenergetics, strength and body composition in breast cancer survivors

Objective: Breast cancer survivors (BCS) are at high risk for loss in skeletal muscle mass, which can be exacerbated by cancer treatment and tumor related factors. While resistance exercise has been shown to be effective in improving strength and physical function in BCS, little is known as to how exercise modulates skeletal muscle bioenergetics in oncology populations. Uncovering these factors are critical for explaining adaptations to exercise among cancer survivors. Therefore, the objective of the THRIVE clinical trial is to determine the effects of resistance exercise training on modulating skeletal muscle bioenergetics in BCS. Hypothesis: We hypothesized that 12 weeks of resistance exercise would improve skeletal muscle bioenergetics, strength and body composition in BCS. Methodology: Preliminary analysis was performed on BCS (n=10; 45.7 ± 11.5 yr) who had completed chemotherapy within the previous 6 months and were recruited to complete 12 weeks of progressive, home-based resistance exercise program (3 supervised training bouts per week). Baseline and 12 weeks strength was assessed with isometric dynamometry and 1 rep max (RM) testing, body composition was measured with DEXA, and physical function was assessed with a 6 minute walk test. Changes in muscle bioenergetics, specifically changes in resting phosphorus metabolites, were assessed using 31-phosphorus magnetic resonance spectroscopy. In the original study design, participants were randomized to either receive creatinine supplement + exercise (n=5) or exercise alone (n=5); however, there were no significant differences between the interventions on the primary outcomes reported here, so the intervention groups were collapsed. Data: Handgrip strength, 1 RM chest press, 1 RM bicep curl, 1 RM leg press and 1 RM leg extension significantly increased (p<0.05) following 12 weeks of training in breast cancer survivors. Twelve weeks of resistance exercise training also significantly increased skeletal muscle phosphodiester (PDE) content and tended to increase total phosphocreatine and gammaATP. There were no significant changes in isometric knee strength, fat mass, lean mass, 6 minute walk testing distance or skeletal muscle inorganic phosphorous. Summary: This preliminary analysis indicates changes in strength and skeletal muscle bioenergetics occur in BCS following a 12-week home-based resistance exercise intervention. Further research is needed to validate these results. The ThriveWell Foundation, NIH (P30 CA054174 and P30 AG044271). 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.

Heavy Metal-Laden Particulate Dust Alters Transcriptional Regulation in Human Colonoids

Chronic heavy metals exposure in the southwestern United States co-occurs with greater incidences of metabolic and digestive diseases, particularly in the Indigenous and Hispanic populations. There is a need to understand how particulate heavy metals drive this dysbiotic state and propose a molecular explanation as a result of these exposures. Previously, our group demonstrated human colonoids to be a relevant model for investigating the physiological impact of environmental toxicants on the intestinal tract. The objective of this study is to elucidate the mechanism behind the transcriptional and cellular changes present in the intestinal epithelia upon acute exposure to non fissile uranium particulate dust. We hypothesize that non-fissile uranium exposure biases the differentiation of progenitor cells in the crypt to secretory roles through miRNA regulation. Colonoids were exposed (18 hours) to non-fissile uranium dust obtained from the Jackpile uranium mine, one of the largest open pit uranium mines, located on the Laguna Pueblo in New Mexico. Control and dust-exposed colonoids (n=3 unique donors) were digested into single cells and processed for droplet-based single cell sequencing (scRNAseq). Upon exposure, enteroendocrine cells (EEC) expanded >4 fold, along with increases in serotonin and PYY, as well as goblet cells (>3 fold) which indicates changes to the secretory lineage. Downstream pathway analysis found microRNAs miR-625-3p, miR-320a, miR-29b-3p to be differentially expressed. These results suggest that acute uranium dust exposure induces changes in differentiation pathways which are modulated by regulatory miRNAs. We would like to expand these findings by performing miRNA sequencing and comparing miRNA expression profiles between UBD exposed and control samples. Our results also provide an improved understanding of uranium dust’s impact on the gastrointestinal system, which may inform other physiological studies on the health of individuals exposed to heavy metals. This study was funded by K01DK106323, R56ES034400, P42ES025589, P20GM121176, P20GM130422, and AGA SURF. 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.

Intestinal Barrier Protection by Probiotic Lactobacillus-Associated Indoles in Caco-2 and Enteroids

Gut bacteria generate from dietary tryptophan (trp) indole compounds, which act as potent signaling molecules intricately involved in the regulation of intestinal homeostasis and barrier integrity. Lactobacillus rhamnosus GG (LGG), a widely used probiotic, has demonstrated ability to restore the gut barrier in animal models of colitis and sepsis, as well as in children with irritable bowel syndrome. To investigate the hypothesis that LGG-derived indoles are responsible for its gut barrier-enhancing properties, we fed gnotobiotic mice trp-suffcient and trp-deficient diets. We then monocolonized them with LGG, using PBS gavaged mice as a control, and analyzed the ileal transcriptome by bulk RNA sequencing and both fecal and serum metabolomes by LC-MS. Using our novel bioinformatic tool METRCA, which correlates metabolites and gene networks, we uncovered an unexpected and substantial influence of indole spatial distribution on genes associated with gut integrity: some were significantly positively linked to tight junction (TJ) genes exclusively from the luminal side, some exclusively from the serum, and others from both. Specifically, we identified nine indoles—indole-acetamide (IAM), indole-carboxaldehyde (IAL), indole-3-lactic acid (ILA), indole-3-propionic acid (IPA), indole-3-acrylic acid (IAR), indole-3-carbinol (ICB), indole-acetic acid (IAA), indole-3-acetonitrile (IAN), and indole-3-carboxylic acid (ICA)—that demonstrated the potential to maintain gut barrier function. To assess their impact, we used a high-throughput system that measured permeability through transepithelial electrical resistance (TEER) and FITC-dextran (4 kDa) in polarized Caco-2 cells. By luminally challenging cells with Clostridium diffcile toxins (TOX), we induced barrier disruption to model leaky gut. Intriguingly, when applied luminally, IAA, IAN, ICA, and ILA rescued the TEER of Caco-2 cells exposed to TOX, while IAM, IAL, and ILA were effective when applied basolaterally, suggesting a strong polar component to their barrier repair capacity. FITC transport revealed a significant basolateral rescue effect of IAM and luminal rescue effect of IAA and ICA, indicating that different sets of indoles are required to repair the pore and leak pathways. Furthermore, we confirmed that basolateral IAM rescued FITC permeability and induced increased expression of TJ genes Tjp1 and Ocln in enteroids challenged with lipopolysaccharides. In summary, our research highlights the potential beneficial therapeutic application of certain indoles in repairing disrupted gut barriers. 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.

Oxidative stress in the remaining muscle after volumetric muscle loss contributes to impaired mitochondrial bioenergetics and is attenuated by SS-31

Volumetric muscle loss (VML) injury results in the non-recoverable loss of muscle mass and function. Our previous studies indicate mitochondrial dysfunction in the remaining muscle fibers after VML injury, marked by changes in mitochondrial respiration, membrane potential, and enzyme activities. In particular, mitochondrial membrane potential is hyperpolarized during the first 14-days post-injury, a condition that could lead to the production of reactive oxygen species (ROS). When ROS emissions exceed the antioxidant buffering capacity, cellular damage can ensue. The primary objective of this study was to determine ROS production, ROS emission, and antioxidant buffering capacity of remaining muscle fibers after VML injury in the first month after injury. The secondary objective of this study was to determine if a mitochondrial antioxidant (SS-31) could mitigate mitochondrial dysfunction after VML injury. We hypothesized that VML injury will alter the redox status of the remaining muscle. Study 1: Male C57BL/6J mice (n=40) were randomized to Uninjured or VML-injured cohorts. ROS (H2O2) emission/production and endogenous antioxidant buffering capacity were analyzed fluorometrically during live muscle fiber respiration (Oroboros O2k) at 3-, 7-, 14-, 21-, and 30-days post-injury. Study 2: Male C57BL/6J mice (n=32) were randomized into two groups: VML and VML+SS-31. SS-31 is a mitochondrial-targeted peptide with ROS-scavenging properties. VML+SS-31 received SS-31 (8mg/kg/day) for 14 days, and the VML received equal volume saline injections. At 14- and 28-days post-VML, mitochondrial respiration and electron conductance, ROS emission, and antioxidant buffering capacity were assessed in permeabilized gastrocnemius muscle fibers from the muscle remaining after the initial injury. Group differences were detected through ANOVA and unpaired t-test. ROS emission and antioxidant buffering capacity were different between VML-injured and Uninjured mice through 14-days post-injury, specifically at 3-, 7-, and 14-days, mitochondrial ROS emission was significantly higher (+28%, p<0.001), and antioxidant buffering capacity was less (-28%, p=0.002) in VML mice compared to Uninjured mice. Two weeks of SS-31 treatment lead to greater muscle fiber respiration and electron conductance (p≤0.008) at both 14- and 28-days post-VML. Importantly, at 14-days post-injury, mitochondrial ROS emission was 71% lower in VML+SS-31 than VML. At both 14- and 28-days post-injury, antioxidant buffering capacity was 12% greater in VML+SS-31 (p≤0.003) compared to VML. Oxidative stress is a feature of early VML pathophysiology marked by greater ROS emission and less antioxidant buffering capacity. Attenuating oxidative stress during the first two-weeks post-VML injury improves mitochondrial respiration. W81XWH-20-1-0885 and R01AR078903 to SG and JC. 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.

Elevated Renal Oxidative Stress and Na+ Transporters are Associated with Hypertension in Postpartum Preeclamptic Rats

Background: Approximately 5-10% of US pregnancies result in preeclampsia (PE). PE is characterized by new onset hypertension (HTN) during pregnancy and is usually accompanied by end-organ damage, especially in the kidneys. Postpartum (PP) women and dams that had PE have an increased risk of developing HTN and chronic kidney disease (CKD) later in life. However, mechanisms linking PE to the long-term development of HTN and CKD are unknown. One aspect that may contribute to renal injury in PP PE women and dams is oxidative stress. Elevated concentrations of oxidative stress have been shown to augment the abundance and activity of renal transporters to increase sodium (Na+) reabsorption and blood volume. These alterations in renal transporters can consequently increase Na+ and water to facilitate HTN. Thus, we hypothesize that at 6 weeks PP (~3 human years), PE dams will display increased oxidative stress, renal Na+ transporter abundance, and elevated blood pressure (BP). Methods: Pregnant Sprague Dawley rats were randomly assigned to two groups: normal (CON) and PE dams. On gestational day 14, the reduced uterine perfusion pressure surgery was performed to mimic placental ischemia and generate a model of PE. Dams gave birth naturally and weaned for 3 weeks. After 6 weeks PP, BP was measured via carotid catheterization, and kidneys were removed and sectioned. Western blots were used to quantify renal Na+ transporters: Na+ K+ 2Cl− transporter (NKCC2) in the kidney medulla (KM) and epithelial Na+ channel (ENaC) in both the kidney cortex (KC) and KM. Oxidative stress was evaluated by heat shock protein 1 (HSP-1), copper zinc superoxide dismutase (CuZnSOD), and manganese superoxide dismutase (MnSOD) via Western blots. Hydrogen peroxide (H2O2) and antioxidant capacity concentrations were assessed via colorimetric assays. Results: PP PE dams had increased BP (126.3±6.18vs105.7±3.74 mmHg, p<0.05) at 6 weeks after birth. KC HSP-1, H2O2, MnSOD, and antioxidant capacity were unchanged between groups. However, KC CuZnSOD protein abundance was decreased in PP PE dams (69.51±11.64vs100±5.73 IU/Protein/Control%, p<0.05). In the KM, HSP-1 abundance (113.7±3.3vs100±5.07 IU/Protein/Control%, p=0.06) and H2O2 concentrations (1.97±0.11vs1.31± 0.38 nM H2O2/mg Protein, p=0.08) were elevated in PP PE dams. MnSOD, CuZnSOD, and antioxidant capacity were unchanged between groups in the KM. No changes occurred in KC and KM ENaC protein abundance. However, NKCC2 protein abundance was elevated by ~50% in PP PE dams (151.71±22.17vs100±5.59 IU/Protein/Control%, p=0.06). Conclusion: In summary, BP, oxidative stress, and NKCC2 were elevated in PP PE dams at 6 weeks. Perhaps, the presence of oxidative stress in the KM may lead to increased NKCC2 abundance. However, more studies are warranted to make this conclusion. NKCC2 elevation may result in increased Na+ and water reabsorption, leading to an increase in BP. Future studies will assess the role of renal oxidative stress to regulate Na+ transporters in PP PE dams and determine the timeline after birth (PP) in which changes in oxidative stress, Na+ transporters, and BP occur. In summary, this study is clinically relevant because it indicates that both oxidative stress and NKCC2 in the KM, separately or together, may have a formative role in the pathogenesis of HTN and CKD in PP PE women later in life. This research was supported by the Neurobiology of Aging and Alzheimer’s Disease Training Program (funded by NIH training grant T32 AG020494). 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.

Sudden Death Induced by Rapid Intravenous Injection of Fentanyl in Conscious Rats

The sudden death induced by rapid intravenous (IVr) injection of overdose FNT in clinical settings is commonly observed in conscious humans and more often in the males than females. Our previous study has shown that IVr injection of FNT induces a long-lasting apnea associated with bradycardia and hypotension in anesthetized rats (Zhuang et al. 2023 EB). This study aimed to determine whether a lethal dose of FNT could cause sudden death with the mortality being higher in male rats than female ones and whether the FNT-induced respiratory disorder, especially ventilatory arrest, but not cardiac arrest, was the trigger of the death. The rat previously instrumented with ECG electrodes and jugular vein cannulation was placed in a restraint tube that was connected to a plethysmograph chamber to record cardiorespiratory activities. We found that FNT at doses <2 mg/kg induced an immediate persistent apnea, lasting less than 1 min, associated with bradycardia. Following restoration of respiratory rhythm, the rats showed depressed VE and bradycardia for several hours and the cardiorespiratory variables recovered next day. A lethal dose of FNT at 3 mg/kg, compared to FNT at <2 mg/kg, induced an even longer apnea (lasting >1.5 min) accompanied with more severe bradycardia. This sustained apnea was usually interrupted by brief restoration of breathing, which was followed by ventilatory and cardiac arrest occurring at approximately 5 min and 10 min post injection respectively. Although the initial cardiorespiratory response to FNT appeared to be similar in both genders, the death rate was relatively higher in male rats than female ones. In conclusion, our study establishes an animal model of IVr injection of overdose FNT-induced sudden death occurring within minutes. The sudden death is the result of ventilatory, but not cardiac, arrest following a brief restoration of respiratory activity from a sustained apnea. Supported by NIH R01 grants HL163512 and DA059063. 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.

Riding for Focus as a Pathway to Improved Mental Health in Middle School Students

Youth mental health remains in a critical state even in a post-COVID pandemic world. Exercise is a well-regarded method to boost mental health and well-being in all age groups. The Riding 4 Focus (R4F) program is a cycling education program designed to equip students with basic cycling handling skills and introduce students to the lifetime physical activity of cycling. A secondary outcome of this program is to improve the behavioral health and well-being of adolescents in middle schools, primarily aged 10-14. The current study examined associations between participating in the R4F program and mental health and well-being in those with specific unmodifiable risk factors including gender, socioeconomic, and racial identity. Anonymous online surveys were collected from 3924 adolescent participants before the R4F program and 3289 students after the cycling program across 31 schools during the fall 2021 and spring 2022 semesters. Psychosocial well-being was quantified using the WHO-5 and PSC-17-Y metrics. Using non-parametric test statistics, the data shows a significant increase in the mental health and well-being of participants after the program. Further analysis revealed that participation in the R4F program was associated with improved psychological health and well-being of minority and low-income adolescents, as well as protective associations for both genders. Although these findings are encouraging, the effcacy of the program depends on a number of factors, and future studies are needed to assess causality. Outride, Loma Linda University School of Medicine, University of Redlands Summer Research Program, P20MD006988. 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 progestinic drug, etonogestrel, rescues breathing in a rodent model of central chemoreflex impairment

The central CO2-chemoreflex is crucial in regulating breathing, providing stimulation at rest and during challenges to homeostasis. The retrotrapezoid nucleus (RTN), located in the ventral brainstem, is essential to this process. Impaired RTN function is linked to hypoventilation syndromes, including congenital central hypoventilation syndrome (CCHS) characterized by apnea and blunted responsiveness to inhaled CO2. Intriguingly, progestins stimulate breathing and CO2-chemoreflexes, and the high-affnity ligand etonogestrel (ETO) has been proposed as a treatment option in CCHS. Our objectives were to address two important gaps-in-knowledge: 1) assess ETO’s ability to “rescue” breathing in a rat model of central CO2-chemoreflex impairment, and 2) determine ETO’s site of action. We generated a model of CO2-chemoreflex impairment in adult female Sprague-Dawley rats using targeted injections of substance-P conjugated saporin toxin. Resulting RTN lesions were classified by the number of surviving chemosensitive neurons vs. non-surgical controls. We first administered systemic ETO (acute/vehicle:1h; or chronic/sham: 28 days) and measured resting ventilation and chemoreflexes (hypercapnia, 7.2% CO2; hypoxia, 10% O2) using whole-body plethysmography. In separate ongoing experiments, ETO was infused directly into target brain regions expressing progesterone receptors. We observed a positive relationship between lesion size and CO2-chemoreflex impairment (hypoxic response was intact). Twenty-one days of systemic ETO reversed CO2-impairment selectively in rats with moderate RTN lesions; large-lesion rats were refractory to ETO’s effects. These data suggest that ETO may enhance the CO2-chemoreflex by inducing neuroplasticity in brain structures with connectivity to surviving RTN chemosensitive neurons. Experiments are ongoing to parse out the site of ETO’s restorative action in the brain. T.A.J.:Canadian Lung Association BaO Fellowship, Canadian Institutes of Health Research (CIHR) Postdoctoral Fellowships. S.C.: Canadian Lung Association BaO Fellowship. S.P.: Women and Children’s Health Research Institute Innovation Grant, CIHR Project scheme grant. Nexplanon was kindly donated by Merck through the Investigator-Initiated Study Program (IISP # 55869; SP). 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.

Crosstalk amongst oxytocin and vasopressin synthesizing neurons of the paraventricular nucleus of the hypothalamus increases blood pressure in mice

The paraventricular nucleus of the hypothalamus (PVH) orchestrates neuroendocrine release and autonomic outflow to maintain body fluid homeostasis and cardiovascular function. Emerging evidence supports the notion that neuropeptides synthesized by PVH neurons create paracrine signals that alter physiology and behavior by affecting the activity of neighboring neurons. Here, we test the hypothesis that PVH neurons synthesizing oxytocin (hereafter referred to a PVHOT) create a paracrine signal that regulates blood pressure. Mice with the expression of Cre-recombinase directed to the OT gene were bred that mice that express a CAG-driven LoxP-flanked stop-codon preceding a channelrhodopsin-2 (ChR2) and eYFP fusion gene at the Rosa26 locus. This produced mice expressing only Cre-recombinase (controls) or mice with ChR2-eYFP expression directed to cells that express oxytocin (OT-ChR2). Confocal image analysis found that ~90% of eYFP expressing neurons were also immunolabeled for OT and electrophysiological recordings obtained from these neurons revealed that pulses of blue light elicited the firing of action potentials. These results confirm directed and functional expression of ChR2 within PVHOT. In vivo optogenetic excitation of PVHOT increased blood pressure and decreased heart rate in OT-ChR2 mice relative to controls. Ganglionic blockade with hexamethonium had no effect on the increased blood pressure elicited by optogenetic excitation of PVHOT but it completely abolished the bradycardia that was previously observed. These results suggest that excitation of PVHOT recruits a neuroendocrine signal that promotes vasoconstriction, which elicits the baroreflex to induce bradycardia by engaging the autonomic nervous system. Consistent with this interpretation, optogenetic excitation of PVHOT increased circulating levels of OT; however, the elevated blood pressure persisted after systemic administration of an OT receptor antagonist. Intriguingly, in vitro optogenetic excitation of PVHOT evoked Ca2+ flux in CHO cells expressing OT or vasopressin receptors (V1aR), suggesting that robust firing of PVHOT is followed by local release of OT. Optogenetic excitation of PVHOT augmented firing of neurons of the PVH that synthesize vasopressin and tended to increase circulating levels of this neuropeptide. Remarkably, systemic administration of a V1aR antagonist completely abolished the increase in blood pressure and bradycardia that were previously observed with in vivo optogenetic excitation of PVHOT. Collectively, these results reveal that robust firing of PVHOT creates an oxytocinergic paracrine signal that increases blood pressure by activating V1aR(s) and increasing circulating vasopressin. AHA 23POST1020034 to KE. NHLBI F31HL1162540 to CBH. NHLBI R01HL136595, R35HL150750, R01HL145028 and NCCIH R65AT012142 to ADK & EGK. 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.