Metabolic Rate Research Articles

Assessment of heart rate measurements by commercial wearable fitness trackers for early identification of metabolic syndrome risk

Metabolic syndrome increases the risks of cardiovascular diseases, type 2 diabetes, and certain cancers. The early detection of metabolic syndrome is clinically relevant, as it enables timely and targeted interventions. In the current study, we aimed to investigate the association between metabolic syndrome and heart rate measured using wearable devices in a real-world setting and compare this association with that for clinical resting heart rate. Data from 564 middle-aged adults who wore wearable devices for at least 7 days with a minimum daily wear time of 20 h were analyzed. The results showed significantly elevated all-day, sleeping, minimum, and inactive heart rates in men with pre-metabolic or metabolic syndrome compared with those in normal individuals, whereas sleeping heart rate and heart rate dips were significantly increased and decreased, respectively, in women with metabolic syndrome. After adjusting for confounders, every 10-beats-per-minute increment in all-day, sleeping, minimum, and inactive heart rates in men corresponded to odds ratios of 2.80 (95% confidence interval 1.53–5.44), 3.06 (1.57–6.40), 4.21 (1.87–10.47), and 3.09 (1.64–6.29), respectively, for the presence of pre-metabolic or metabolic syndrome. In women, the association was significant only for heart rate dips (odds ratio = 0.49 [95% confidence interval 0.25–0.96] for every 10% increment). Models incorporating inactive or minimum heart rate in men and heart rate dip in women demonstrated better fits, as indicated by lower Akaike information criterion values (170.3 in men and 364.9 in women), compared with models that included clinical resting heart rate (173.4 in men and 369.1 in women). These findings suggest that the heart rate indices obtained from wearable devices may facilitate early identification of metabolic syndrome.

Respiratory Intervals and Swimming Speed as Remotely Sensed Health Metrics in Free-Ranging Killer Whales (Orcinus orca).

Respiratory rate (mean number of breaths per minute) and respiratory interval (mean time between breaths) can offer insight into a diving mammal's activity state, metabolic rate, behavior, and synchronization due to social cohesion. Also, respiratory rate can reflect an individual animal's health and has the potential to be an informative remotely assessed health metric for monitoring individual animal health in endangered whale species and populations such as southern resident killer whales (Orcinus orca). Using data collected from noninvasive, land-based theodolite tracking, we analyzed swimming speed and surfacing intervals (i.e., mean dive time or mean time between breaths) from 20,613 surfacings of 98 individuals from two populations of the fish-eating, resident killer whale ecotype, namely, one growing (northern resident) and one declining and endangered (southern resident) population. Focal animal sampling was used to measure behavior of individuals of known age and sex in various activity states. Our objective was to evaluate variability and generate normal ranges for respiratory intervals and swimming speeds for killer whales of the Northeast Pacific Ocean resident, fish-eating ecotype to identify baseline respiratory intervals. We found that median respiratory intervals for fish-eating killer whales were between 26 and 29 s for all activity states and that swimming speeds varied by activity state. Median swimming speeds were similar for foraging and traveling (1.6 and 1.7 m/s, respectively), but were significantly slower during resting (1.1 m/s) and social activity (1.3 m/s) states. Three southern resident killer whales in poor body condition (had body condition scores in the lowest 20th percentile of the population) swam at reduced speeds and had shorter median respiratory intervals than outwardly healthy whales of similar age and sex. Respiratory rates, respiratory intervals, and swimming speeds are valuable remotely sensed metrics of health for free-swimming killer whales, especially when combined with other metrics as is the standard in veterinary examinations.

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The article presents a combined, shared pedagogical practice implemented in two parts: a shared project-based practice “Curious and useful tips for food and drink” in grade VIII and an extracurricular school practice “Week of healthy foods and nutrition” for high school students. The practice is a way to inform, increase competences, build a model for a critical choice of food and drinks and for a balanced, complete, high-quality, regular and healthy diet of teenagers. Students learn to use digital health and energy calculator applications, calculate BMI (body mass index) and BEE (basal energy metabolism), determine their health status in relation to food and nutrition, combine foods correctly, create personal nutrition programs, select foods according to your blood type and their color. In “Healthy Foods and Nutrition Week”, students participate in various competitions, learn about the science of nutrition, carving techniques, design and presentation of healthy foods and traditional foods from European countries. The practice builds up the knowledge, skills and habits of the students of Professional School of Design “Elisaveta Vazova” for healthy eating and a healthy lifestyle.

Near maximally swimming schoolmaster snapper (Lutjanus apodus) have a greater metabolic capacity, and only a slightly lower thermal tolerance, than when tested at rest.

To assess the relationship among various measures of thermal tolerance and performance suggested for use in fish, we determined the critical thermal maximum (CTmax), Ucrit, maximum thermal tolerance while swimming [CTSmax] and realistic aerobic scope (ASR) of juvenile schoolmaster snapper (Lutjanus apodus). Their CTSmax (37.5±0.1°C) was only slightly lower than their CTmax (38.9±0.1°C), and this is likely because their maximum metabolic rate (MMR) and ASR during the former test were∼42 and 65% higher, respectively. Further, we did not observe a transition to unsteady (i.e., anaerobically fueled) swimming in the CTSmax test as we did in the Ucrit protocol. These data strongly suggest that thermal tolerance tests on fishes whose lifestyle involves schooling or sustained activity should be performed at ecologically-relevant swimming speeds. Further, they do not support the hypothesis that failure during a CTSmax test is due to a fish's inability to meet its tissue oxygen demands.

Metabolic Rate of Goldfish (Carassius auratus) in the Face of Common Aquaculture Challenges

This study examined the metabolic rate (MO2, oxygen consumption) of goldfish (Carassius auratus) under normal management conditions in aquaculture. Using an intermittent respirometry system, we assessed daily variations and the effects of feeding, handling, temperature increase, and anesthetics. MO2 exhibited a daily rhythm, with higher values during day. Feeding to satiety produced a 35% increase in MO2 compared to fasted animals, with a maximum peak after 3 h and returning to baseline after 7 h. Handling stress (5 min) produced a 140% MO2 peak (from 180 to 252 mg O2 kg−1 h−1), returning to the routine MO2 after 2.5 h. An increase in water temperature (+0.1 °C min−1) up to 30 °C caused MO2 to peak at 200% after 2.5 h from the start of the temperature increase. The use of common anesthetics in aquaculture (MS-222, 2-phenoxyethanol and clove oil in deep anesthesia concentration) affects MO2 during the first few minutes after anesthetic recovery, but also during the following 4 h. It can be concluded that the metabolic rate is a good indicator of the goldfish’s response to aquaculture practices involving energy expenditure and stress. Thus, intermittent respirometry is a valuable non-invasive tool for understanding and improving fish welfare in aquaculture.

NIR-II Anti-Stokes Luminescence Nanocrystals with 1710 nm Excitation for in vivo Bioimaging.

Anti-Stokes luminescence (ASL) based on lanthanide nanocrystals holds immense promise for in vivo optical imaging and bio-detection, which benefits from filtered autofluorescence. However, the current longest emission and excitation wavelengths of lanthanide ASL system were shorter than 1200 nm and 1532 nm, respectively, which limited tissue penetration depth and caused low signal-to-noise ratio (SNR) of in vivo imaging due to tissue scattering and water absorption. In this work, we extended the excitation wavelength to 1710 nm with the second near-infrared (NIR-II, 1000-1700 nm) emission up to 1650 nm through a novel ASL nanocrystal LiYF4:10%Tm@LiYF4:70%Er@LiYF4. Compared with 1532 nm excited ASL nanoprobes, the 1710 nm excited nanocrystals could improve in vivo imaging SNR by 12.72 folds. Based on this excellent imaging performance of the proposed ASL nanoprobes, three-channel in vivo dynamic multiplexed imaging was achieved, which quantitatively revealed metabolic rates of intestinal dynamics and liver enrichment under anesthetized and awake states. This innovative ASL nanoprobes and dynamic multiplexed imaging technology would be conducive to optimizing dosing regimen and treatment plans across various physiological conditions.

NIR‐II Anti‐Stokes Luminescence Nanocrystals with 1710 nm Excitation for in vivo Bioimaging

Anti‐Stokes luminescence (ASL) based on lanthanide nanocrystals holds immense promise for in vivo optical imaging and bio‐detection, which benefits from filtered autofluorescence. However, the current longest emission and excitation wavelengths of lanthanide ASL system were shorter than 1200 nm and 1532 nm, respectively, which limited tissue penetration depth and caused low signal‐to‐noise ratio (SNR) of in vivo imaging due to tissue scattering and water absorption. In this work, we extended the excitation wavelength to 1710 nm with the second near‐infrared (NIR‐II, 1000‐1700 nm) emission up to 1650 nm through a novel ASL nanocrystal LiYF4:10%Tm@LiYF4:70%Er@LiYF4. Compared with 1532 nm excited ASL nanoprobes, the 1710 nm excited nanocrystals could improve in vivo imaging SNR by 12.72 folds. Based on this excellent imaging performance of the proposed ASL nanoprobes, three‐channel in vivo dynamic multiplexed imaging was achieved, which quantitatively revealed metabolic rates of intestinal dynamics and liver enrichment under anesthetized and awake states. This innovative ASL nanoprobes and dynamic multiplexed imaging technology would be conducive to optimizing dosing regimen and treatment plans across various physiological conditions.

Energy costs of the sponge pump

Sponges pump large volumes of water to obtain nutrition from a dilute suspension of food particles and dissolved organic matter. Our review of the literature shows pumping power ranging from 0.85% up to 28% of the total metabolic respiration rate Rtot, where the pumping power (Pp = pumping rate × pump pressure) is the energy per unit time transferred to the water flow. Some published values of pumping costs are high while others are low due to incorrect estimates of some pressure losses in the aquiferous system of sponges. However, as improved descriptions of detailed structures and function, especially of the filter apparatus of the choanocytes, have become available, our corrected values for pressure losses show the respiration-specific pumping costs of Pp/Rtot = 1.3 to 22%. The stated pumping cost is based on the minimal (theoretical) pump power delivered to the water, which excludes a mechanical efficiency of pump action and a metabolic efficiency that expresses the fraction of total metabolism that is devoted to driving the pump action, considerations that should be included in future studies.

Pharmacokinetic analysis and simplified uptake measures for tumour lesion [18F]F-AraG PET imaging in patients with non-small cell lung cancer.

The novel positron emission tomography (PET) imaging tracer, [18F]F-AraG, targets activated T-cells, offering a potential means to improve our understanding of immune-oncological processes. The aim of this study was to determine the optimal pharmacokinetic model to quantify tumour lesion [18F]F-AraG uptake in patients with non-small cell lung cancer (NSCLC), and to validate simplified measures at different time intervals against the pharmacokinetic uptake parameter. Ten patients with early-stage NSCLC and three patients with advanced NSCLC underwent a dynamic PET scan of minimal 60min. Venous and/or arterial blood sampling was obtained at maximum seven time points. Tumour lesion time activity curves and metabolite-corrected input functions were analysed using single-tissue reversible (1T2k), two-tissue irreversible (2T3k) and two-tissue reversible (2T4k) plasma input models. Simplified uptake measures, such as standardised uptake value (SUV) and tumour-to-blood (TBR) or tumour-to-plasma ratio (TPR), were evaluated for different time intervals. Whole-blood and plasma radioactivity concentrations showed rapid clearance of [18F]F-AraG. Metabolite analysis revealed a low rate of metabolism, at 70min p.i., on average, 79% (SD = 9.8%) of the total radioactivity found in blood corresponded to intact [18F]F-AraG. The time activity curves were best fitted by the 2T3k model. Strong positive correlations were found for SUV (body weight (BW), lean body mass (LBM) or body surface area (BSA) corrected), TBR and TPR for any time interval between 20 and 70min p.i. against the 2T3k-derived Ki. The correlation of TBR at 60-70min p.i. with 2T3K-derived Ki (r (df = 20) = 0.87, p < 0.01), was stronger than for SUVBW (r (df = 20) = 0.80, p < 0.01). Tumour lesion [18F]F-AraG uptake in patients with NSCLC is characterised by a 2T3k model. TBR and TPR show most potential for simplified quantification of tumour lesion [18F]F-AraG uptake in patients with NSCLC.

Evidence for SARS-CoV-2 infected Golden Syrian hamsters (Mesocricetus auratus) reducing daily energy expenditure and body core temperature

Golden Syrian hamsters (Mesocricetus auratus) are a well-established animal model for human infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) due to their susceptibility to SARS-CoV-2 infection, robust virus replication and pathological manifestations similar to human COVID-19 pneumonia. To investigate the physiological changes upon infection in this animal model, we explored the alterations in daily energy expenditure (DEE), water turnover, body mass, body temperature, and locomotor activity in non-infected and SARS-CoV-2 infected Golden Syrian hamsters for four days post SARS-CoV-2. DEE was measured using the doubly labelled water method, which allows for the accurate estimation of carbon dioxide production and, consequently, energy expenditure in animals. Additionally, we investigated total water intake (TWI), which comprises drinking water, preformed water in food, and metabolic water. Using intraperitoneally implanted data loggers, we also monitored body core temperature and locomotor activity in some of the animals. Here we provide evidence for infected hamsters exhibiting significantly lower DEE and TWI compared to non-infected animals. We also observed an increase in body weight in the non-infected animals, while infected animals experienced weight loss. Further, infected animals showed a significantly decreased body temperature, indicating a generally lowered metabolic rate.

Metabolic Rate and Oxidative Stress as a Risk Factors in the Development of Colorectal Cancer

There is growing evidence that the body’s energy expenditures constitute a significant risk factor for the development of most deadly diseases, including cancer. Our aim was to investigate the impact of basal metabolic rate (BMR) on the growth and progression of colorectal cancer (CRC). To do so, we used a unique model consisting of three lines of laboratory mice (Mus musculus) artificially selected for high (HBMR) and low (LBMR) basal metabolic rate and randomly bred individuals (non-selected, NSBMR). The experimental individuals were implanted with human colorectal cancer cells DLD-1. The variation in BMR between the lines allowed for testing the impact of whole-body metabolism on oxidative and antioxidant parameters in the liver throughout the cancerogenesis process. We investigated the dependence between metabolic values, reactive oxygen species (ROS) levels, and Kelch-like ECH-associated protein 1-based E3 ligase complexes (Keap1) gene activity in these animals. We found that the HBMR strain had a higher concentration of oxidative enzymes compared to the LBMR and NSBMR. Furthermore, the growth rate of CRC tumors was associated with alterations in the levels of oxidative stress enzymes and Keap1 expression in animals with a high metabolic rate. Our results indicate that a faster growth and development of CRC line DLD-1 is associated with enzymatic redox imbalance in animals with a high BMR.

12475 Revisiting Myxedema Coma

Abstract Disclosure: M.H. Islam: None. D.R. Jimenez Corado: None. S. Siddiqui: None. M.F. Aquino Camey: None. S. Yeasmin: None. Background: Myxedema coma is a rare and life-threatening complication of hypothyroidism.Although it is rare in the era of better diagnostics and treatment modalities, its life-threatening nature mandates its timely recognition and better understanding. Case:81-year-old female with a history of hypothyroidism (unclear medication compliance) and alcohol use disorder was admitted due to alcohol withdrawal and treated with benzodiazepines. A few days prior to the presentation, she was found to have worsening confusion, unsteady gait, and multiple falls. On presentation, she was hemodynamically stable, tremulous, anxious, and oriented to person only. Blood work was remarkable for mild transaminitis. CT scan of the head revealed sequelae of microvascular disease. The day after admission, she was noted to be lethargic, and benzodiazepines were held. Later, she became hypothermic, hypotensive, bradycardic, and hyponatremic. Further investigation was pursued, revealing a TSH of 55 (normal 0.27 to 4.2 mlU/L), free T4 of &amp;lt;0.10 ng/dL (normal 0.8-1.7 ng/dL), free T3 of &amp;lt;1.0 pg/mL (normal 2.2-4 pg/mL), and cortisol of 10.7 ug/dL. Due to concerns of myxedema coma, she was started on stress dose steroids and IV levothyroxine. She was transferred to the ICU as her mental status continued to deteriorate; she underwent endotracheal intubation and received additional doses of IV levothyroxine and liothyronine. After a few days, her clinical condition and her cortisol, free T4, and free T3 levels improved; she was extubated and later discharged with an adjusted levothyroxine dose. Conclusion: It is of absolute importance to keep myxedema coma as a differential diagnosis when evaluating encephalopathic elderly patients, especially those with a history of thyroid disorders.There is a paucity of evidence to suggest a clear benefit of combining levothyroxine-liothyronine over levothyroxine alone. Treating initially with intravenous levothyroxine over oral is beneficial, as GI absorption and bioavailability are likely variable and unpredictable. In this case, oral liothyronine was used with IV levothyroxine to speed up clinical and biochemical recovery.Adrenal insufficiency often coexists with hypothyroidism, with considerable overlap in clinical features like hypotension, hypoglycemia, and hyponatremia. Administration of levothyroxine before steroids can lead to a rapid increase in metabolic rate and subsequent depletion of the existing reserves. Considering this, it can be said with fair confidence that patients need prior or concomitant stress doses of corticosteroids on an emergent basis. Later, biochemical testing can be done to evaluate the functioning of the hypothalamic-pituitary-adrenal axis and then adjust steroid doses accordingly. Presentation: 6/1/2024

7288 A Preclinical Mouse Model of Gender-Affirming Hormone Therapy: Metabolic and Behavioral Outcomes

Abstract Disclosure: A. Yasrebi: None. K. Otersen: None. O. Groh: None. E. Guthman: None. I. Shmarakov: None. S. Campbell: None. T.A. Roepke: None. The long-term metabolic effects of gender-affirming hormone therapy (GAHT) is largely unknown, in part, due to the lack of properly designed preclinical animal models. Here we propose a rodent study design, beyond the classical endocrine model of gonadectomy and steroid treatment, to accurately reflect the reality of the trans experience. Specifically, trans women do not all seek or undergo orchidectomy (ORX) instead take estrogen supplementation along with an androgen blocker such as finasteride. In this study, 40 WT C57 male mice were divided into 4 groups of 10 mice - 1) intact with oil vehicle, 2) intact with estradiol benzoate (EB, 150 μg/kg/d) and finasteride (F, 0.25 mg/kg/d), 3) ORX with oil; and ORX with EB (150 μg/kg/d). Each mouse was dosed daily for 8 weeks while on a standard chow diet. Mice were pair housed and food intake and body weight were collected weekly prior to behavioral (open field, elevated plus, Y-maze) and metabolic (body composition, metabolic rates, activity, tolerance testing) phenotyping. Intact mice treated with EB+F exhibited less avoidance behaviors, potentially due to differences in movement, with no differences between treatments in the Y-maze. Cumulatively, Intact:EB+F gained less weight than Intact:oil (3.4 ± 0.4 g vs 5.3 ± 0.4 g), while ORX:oil mice gained less than ORX:EB (2.2 ± 0.5 g vs 5.5 ± 0.7 g). These interactive effects were due to differences in the gain of fat or lean mass between ORX and intact and lower cumulative food intake in ORX:oil mice (136 ± 3.8 g vs Intact:oil: 159 ± 4.9 g; Intact:EB+F: 167 ± 6.1 g; ORX:EB: 171 ± 3.4 g). Metabolic assessments found that Intact:EB+F exhibited elevated V.O2, V.CO2, and heat production in the light and dark cycle compared to Intact:oil, while ORX:EB only exhibited elevated heat production compared to ORX:oil. Similarly, Intact:EB+F and ORX:EB moved more than their counterparts during the dark cycle; however, only Intact:EB+F exhibited elevated wheel running. Tolerance tests (i.p.) found that glucose clearance was augmented in ORX:EB mice while insulin-induced glucose clearance was lower in Intact:EB+F compared to Intact:oil but modestly elevated by EB in ORX mice. These data, along with suppressed fasting blood glucose in ORX:EB mice, suggest that glucose homeostasis is differentially modulated by GAHT paradigms in mice. Analysis of hypothalamic, hepatic, adipose, and intestinal gene expression is currently underway. Collectively, these data, generated by using a translationally-relevant preclinical animal model, are the first to establish that metabolism is differentially affected by both steroid treatments and ORX and suggesting that the long-term metabolic effects of GAHT are dependent on the type of treatment. The underlying mechanisms and sites of action remain to be investigated. Presentation: 6/3/2024

7447 Rare KSR2 Variants: The Effect of Glycine and N-acetylcysteine (GlyNAC) Supplementation

Abstract Disclosure: J. Youn: None. Y. Carcamo-Bahena: None. E. Lartigue: None. S. Sisley: None. Kinase suppressor of ras 2 (KSR2) is an intracellular scaffolding protein involved in multiple signaling pathways. Of note, disruption of the kinase domain of KSR2 in humans and mice causes obesity by reducing metabolic rate, suggesting its important role in energy homeostasis. In the present study, we identified two variants (P189L, T290A) with mutations located in the proximal CA2 region from children with severe, early-onset obesity. Since variants in this region have not been confirmed to cause obesity, we generated plasmid constructs containing these KSR2 mutations by site directed mutagenesis. The HEK293 cells transfected with KSR2 plasmid construct containing P189L or T290A had reduced binding affinity with AMPK and phosphorylation of AMPK without affecting KSR2 protein integrity. These variants also significantly reduced cellular metabolic rates measured by Seahorse analysis in C2C12 cells, suggesting that KSR2 variants in the proximal CA2 region can result in impaired KSR2 function, subsequently leading to a decrease in cellular metabolic rate. In addition, these KSR2 variants decreased protein levels of NRF-2, a transcription factor of cytoprotective genes regulating the antioxidant glutathione (GSH) pathway compared to wild type KSR2 which augmented NRF2 levels. We also observed lower levels of total GSH and GSH/Glutathione disulfide (GSSG) ratio and higher levels of thiobarbituric acid reactive substances (TBARS), an indicator of oxidative stress, indicating an imbalance of antioxidant and oxidant with proximal KSR2 variants. However, treatment of cells with Glycine and N-acetylcysteine (GlyNAC) reversed the detrimental effects of KSR2 variants by normalizing protein expression levels of NRF-2, GSH/GSSG ratios and TBARS levels. Taken together, we show strong evidence that two new KSR2 variants, P189L and T290A, cause disruption of KSR2 function. Additionally, we also report a novel role of KSR2 in maintaining redox homeostasis suggesting that increased oxidative stress following GSH deficiency may play an important role in the development of obesity from KSR2 variants. Presentation: 6/1/2024

Assessing the thermal limits and metabolic profiles of small indigenous fish species: Informing conservation and aquaculture in a changing climate

This study explored the thermal tolerance and routine metabolic rate of ten small indigenous fish species from Northeast India: Amblypharyngodon mola, Esomus danrica, Puntius sophore, Gudusia chapra, Heteropneustes fossilis, Botia dario, Lepidocephalichthys guntea, Mystus cavasius, Aplocheilus panchax, and Glossogobius giuris. Fish were acclimated to 20°C, 25°C, and 30°C for two weeks prior to experiments and assessed for critical thermal maxima (CTmax), critical thermal minima (CTmin), lethal thermal maxima (LTmax), oxygen consumption rates, and respiratory quotients using standardized methods. The results revealed significant interspecific variations: CTmax ranged from 36.4°C to 41.7°C, CTmin from 8.7°C to 15.2°C, and LTmax from 41.5°C to 44.9°C. Oxygen consumption rates varied between 0.26 and 1.07 mg O₂/g/h, with respiratory quotients ranging from 0.76 to 1.01. Heteropneustes fossilis (CTmax: 41.7°C at 30°C acclimation) exhibited the highest thermal tolerance, while Amblypharyngodon mola had the lowest (CTmax: 38.2°C at 30°C acclimation). Differences in thermal tolerance between species were statistically significant (p<0.05). Notably, CTmax was positively correlated with oxygen consumption rates, suggesting a connection between metabolic rate and heat tolerance. These findings enhance our understanding of the physiological adaptations of these species to their thermal environments and underscore their conservation needs amidst climate change.

8538 Pancreatic Islet Adaptations to Hyperglycemia Are Prevented by Glycolytic Inhibition and Amplified by Inhibiting Membrane Depolarization

Abstract Disclosure: N.B. Whitticar: None. B.P. List: None. N. Bruce: None. R. Bertram: None. C.S. Nunemaker: None. Long before type 2 diabetes ensues, pancreatic islets undergo functional changes to compensate for increasing insulin resistance. Primarily, the islets increase their ability to secrete insulin by augmenting the glucose-stimulated insulin secretion (GSIS) pathway. As metabolic syndrome worsens, islets become functionally exhausted, leading to cellular dysfunction and apoptosis. To avoid the negative consequences of this compensatory response, various steps of the GSIS pathway can be attenuated to restore normal functional levels before the islets fail. Determining which inhibitors can prevent the earliest adaptations to hyperglycemia may reveal the processes that play a causal role in islet failure. The chemicals mannoheptulose (MH), diazoxide (DZ), and nifedipine (NP) were chosen to inhibit the glucokinase enzyme, KATP-channel closure, and voltage-gated calcium channels, respectively. CD-1 mouse islets were placed in 20 mM glucose to simulate hyperglycemia along with a concentration of each inhibitory drug that reduced insulin secretion by 30-40%. After 48-hour treatment, glucose-stimulated calcium tests were performed to determine if the treatments could prevent the negative adaptation to hyperglycemia. Only islets treated with MH to reduce glycolytic activity maintained a normal calcium response. Islets in the MH group also retained a strong insulin response to glucose and were not depleted of insulin content. Unexpectedly, inhibition of calcium influx and insulin secretion with DZ or NF caused a substantial increase in basal insulin secretion compared to islets in standard culture (P&amp;lt;0.01, n=6; P=0.06, n=6, respectively). These results indicate that the signaling pathway that causes the adaptation to hyperglycemia lies upstream of KATP channels and downstream of glucokinase. Mathematical modeling using the Integrated Oscillator Model was able to replicate our results and suggests that high rates of glycolytic and mitochondrial metabolism are associated with the signal that adapts islets to hyperglycemia, and that reducing intracellular calcium in the face of high glucose further increases basal insulin secretion. Ongoing studies will determine if metabolic acceleration or altered membrane conductance are responsible for the earliest islet adaptations to hyperglycemia. Our results suggest that reducing metabolic activity, but not calcium influx, prevents adaptations to hyperglycemia in mouse islets. These findings can be applied to potentially prevent the progression of obesity and hyperinsulinemia into type 2 diabetes. Presentation: 6/2/2024

6724 A Broken Heart Due to Excess Thyroid

Abstract Disclosure: R. Subramani: None. R. Subramani: None. V. Zeykan: None. Introduction: Tachycardia-induced cardiomyopathy related to thyrotoxicosis is an uncommon yet serious complication affecting fewer than 1% of individuals with hyperthyroidism. Restoring a euthyroid state can potentially reverse the abnormal cardiac structure and function. Here we report a case of tachycardia-induced cardiomyopathy secondary to thyrotoxicosis Case Summary: A 52-year-old woman with a history of hypertension presented with recent-onset exertional dyspnea, a nonproductive cough, and paroxysmal nocturnal dyspnea. On examination, she exhibited tachycardia (heart rate: 150/min), tachypnea, hypertension, and was afebrile. Physical findings included a mildly enlarged, firm, non-tender thyroid gland bilaterally, without exophthalmos or tremors. Auscultation revealed bilateral crackles in the left lower lung fields. Laboratory analysis revealed undetectable TSH (&amp;lt;0.02 uIU/mL), elevated free T4 (5.3 ng/dL), free T3 (16.30 pg/mL), thyroid stimulating immunoglobulin (TSI) at 216%, and NT proBNP at 8528 pg/mL. Neck ultrasound and CT confirmed diffuse enlargement of the thyroid gland. Transthoracic echocardiography (TTE) displayed severely depressed left ventricular systolic function, estimating an ejection fraction (EF) of 25-30%. Initial management involved intravenous beta-blockers for heart rate control, IV Lasix, and IV hydrocortisone. Subsequently, the patient received propylthiouracil, propranolol, and prednisone, resulting in symptomatic improvement. A follow-up TTE after 6 months revealed an improved EF of 50%. Discussion: The pathophysiologic mechanisms underlying thyrotoxic cardiomyopathy encompass several factors, including tachycardia-induced cardiomyopathy, direct myopathic effects induced by the T3 hormone, and concurrent autoimmune myocarditis associated with Graves' disease. Thyroid hormone exerts a comprehensive impact on nearly all tissue and organ systems, heightening basal metabolic rate and subsequently increasing preload, myocardial contractility, and cardiac output. While thyrotoxicosis-related congestive heart failure (CHF) is relatively uncommon among patients hospitalized for acute CHF, addressing hyperthyroidism and CHF through definitive treatment yields a more favorable prognosis compared to cases of acute CHF stemming from other etiologies. The intricate interplay of these mechanisms highlights the importance of a comprehensive approach in managing thyrotoxic cardiomyopathy, emphasizing the need for targeted interventions to address both the underlying thyroid dysfunction and associated cardiac manifestations. Presentation: 6/3/2024

Metabolic Shifts Induced by Helminth Infections and Their Contribution to Stunting in Vulnerable Populations

Aims: to revisit the condition of chronic metabolic shifting caused by immunomodulatory sequence facilitated by helminth infection together with other deteriorating condition such as persistent exposure to infection which contributes to stunting formation. Discussion: During dynamic interaction between active helminth infection and the host, the helminth and its excretory/secretory products induce and arouse the type 2 immune response which drives host tolerance and plays an important role in promoting tissue repair. Helminths also activates M2 Macrophages and induce a metabolic shift, even metabolic reprogramming towards reliance on oxidative phosphorylation, lipid oxidation and amino acid metabolism. Helminth-induced activation and metabolic reprogramming of macrophages precede the improvement in overall whole-body metabolism, denoted by improved insulin sensitivity, body mass in response to high-fat diet and atherogenic index in mammals. Contributions of altered nutrient uptake, adipose tissue function and/or the intestinal microbiota with the ability of helminths to alter metabolic status play a pivotal role in increased metabolism rate and may lead to wasting and even stunting formation. Conclusion: Helminth drives the type 2 immunity and activates its cell line which is responsible for metabolic shifting and reprogramming.

8040 Precision-Engineered Activin and GDF Ligand Trap HS235: A Novel Lean Mass-Preserving Treatment for Obesity

Abstract Disclosure: G. Schang: Employee; Self; 35Pharma. M. De Molliens: Employee; Self; 35Pharma. E. Brule: Employee; Self; 35Pharma. C. Chauvet: Employee; Self; 35Pharma. J. Denis: Employee; Self; 35Pharma. A. Sours: Employee; Self; 35Pharma. V. Ganesh: Employee; Self; 35Pharma. G. Tremblay: Employee; Self; 35Pharma. J. Schoelermann: Employee; Self; 35Pharma. M. O'Connor: Employee; Self; 35Pharma. Introduction: Novel anti-obesity medications including incretin mimetics have revolutionized the pharmacotherapy of obesity and type 2 diabetes, leading to unprecedented weight loss and clinically meaningful improvement of glucose metabolism and cardiometabolic health. However, incretins reduce body mass in a non-selective manner; both fat mass and lean mass are lost with incretin treatment. In obese patients treated with incretins, undesirable loss of lean body mass (LBM) can account for up to 40% of overall weight loss. Loss of LBM negatively impacts resting metabolic rate, leading to a weight loss plateau and often unsustainable results. Furthermore, individuals with sarcopenia, characterized by low muscle mass and strength, are at greater risk for heart failure. The preservation, or even increase, of LBM is therefore a desirable treatment goal for obesity pharmacotherapy and overall cardiometabolic health. Activins and growth differentiation factors (GDFs), which are members of the TGF-beta superfamily, are validated targets controlling body composition and metabolism. Specifically, blockade of activins and GDFs has anabolic effects in metabolically active tissues such as skeletal muscle and brown adipose tissue, while reducing white adipose tissue mass. Therefore, specific and selective blockade of activins and GDFs represents a novel anti-obesity treatment strategy which can act orthogonally to current anti-obesity medications. HS235 is an activin receptor ectodomain-based (ActR) Fc-fusion protein that has been rationally designed to attain optimal inhibition of ligands controlling body composition in obesity. Methods: A structure-assisted rational molecular engineering approach coupled with cell-based potency screening was employed to design HS235. To validate the anti-obesogenic potential of HS235, diet-induced obese (DIO) mice were injected with HS235, an incretin mimetic, or a combination of both. Fat mass, LBM, muscle weights, and biomarker readouts were assessed at the end of study. Results: In cell-based assays, HS235 potently and selectively neutralized activins and GDFs implicated in body composition. This translated to complete in vivo target engagement and pharmacodynamic response. In a DIO mouse model, both HS235 and the incretin mimetic significantly improved metabolic parameters and decreased fat mass, but only HS235 increased LBM, while incretin-based treatment led to LBM loss. Importantly, the addition of HS235 to the incretin mimetic lead to a synergistic fat mass loss and prevented loss of LBM. Conclusion: Potent and selective inhibition of activins and GDFs by HS235 represents a novel LBM preserving weight loss strategy orthogonal to incretin mimetics. Collectively, these data support the development of HS235 as a novel anti-obesity agent to complement currently approved incretin-based medications to improve quality of weight loss. Presentation: 6/3/2024

7494 Glycerol Phenylbutyrate Treatment of Two Patients with Monocarboxylate Transporter 8 Deficiency

Abstract Disclosure: A. Zung: None. N. Sonntag: None. U. Schweizer: None. E. Banne: None. D. Braun: None. Context: Monocarboxylate transporter 8 (MCT8) deficiency is a rare genetic disease that leads to severe global developmental delay. MCT8 facilitates thyroid hormone (TH) transport across the cell membrane, and the serum TH profile is characterized by high T3 and low T4 levels. Currently, the two thyromimetic agents 3,5-diiodothyropropionic acid (DITPA) and triiodothyroacetic acid (TRIAC) have been evaluated in the treatment of these patients, as they both partially restore intracellular TH action independent of MCT8. Recent studies have shown that the chemical chaperone sodium phenylbutyrate (NaPB) restored mutant MCT8 function and increased TH content in patient-derived induced pluripotent stem cells, making it a potential treatment for MCT8 deficiency. Objective: We aimed to assess the efficacy and safety of glycerol phenylbutyrate (GPB) in MCT8 deficiency. Methods: We treated two monozygotic twins aged 14.5 years with MCT8 deficiency due to P321L mutation with escalating doses of GPB over 13 months. We recorded TH, serum markers of peripheral hyperthyroidism, vital signs, anthropometric measurements and neurocognitive functions by several neurodevelopment validated tests. Resting metabolic rate (RMR) was measured by indirect calorimetry. Serum metabolites of GPB were monitored as a safety measure. In-vitro effects of NaPB were evaluated in MDCK1 cells stably expressing the MCT8P32[1]L mutation. Results: NaPB restored mutant MCT8 expression in MDCK1 cells and increased T3 transport into cells carrying the P321L mutation. GPB treatment yielded a dose-dependent decrease in FT3 and an increase in FT4 serum levels. The patients showed an elevation in cholesterol levels in parallel with GPB dose, but sex-hormone binding protein (SHBG), another marker of peripheral hyperthyroidism was not affected. The patients showed a significant weight gain simultaneously with a reduction in RMR. Only minor neuro-cognitive improvement was observed, mainly in hyperreflexia score, slight improvement in gross motor functions and a mild progression in cognitive functions. Serum metabolites of GPB did not exceed the toxic range but elevated liver transaminases restricted the dose intensification of GPB. Conclusions: In the first report of GPB treatment in MCT8 deficiency patients we found an improvement in TH profile and body-mass index (BMI). The reduction in T3 levels could contribute to the remarkable increase in BMI-SDS, since various aspects of peripheral hyperthyroidism in MCT8 deficiency, including poor weight gain, were attributed to elevated T3. The limited effects of GPB treatment on cognitive and motor functions can derive from the advanced age of the patients at the time of the intervention. Presentation: 6/2/2024