bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metabolism as a Target for Age‐Related Muscle Mass and Functional Loss
Authors: Schaar Anne , Balasubramanian Priya , Diffee Gary , Anderson Rozalyn 
Published: April 2020

The progressive age‐related loss of skeletal muscle mass and function, known as sarcopenia, increases the risk for impaired mobility, falls, fractures, and mortality. Currently, there are no pharmacological interventions to prevent or treat sarcopenia. Here we show that stimulation of adiponectin signaling in skeletal muscle by AdipoRon, a pan‐adiponectin receptor agonist, stimulates pathways linked to exercise and improves muscle function in old mice.Intravenous delivery of AdipoRon (1.2mg/kg bw; 3 times per week, 6 weeks) activated the AMPK‐PGC‐1a axis in skeletal muscle and induced changes in fiber type distribution in young (5 months) and old (24 months) male C57Bl6/J mice. In old mice, AdipoRon treatment improved running endurance and muscle contractile force. To explore mechanisms and enhance translational potential, the response to oral delivery through diet of AdipoRon (10, 25, or 50 mg/kg; daily feeding, 16 weeks) was investigated in young male and female C3B6F1 mice. AdipoRon enhanced insulin sensitivity and decreased body mass in females, however, these changes were not displayed in males. Increased expression of Ppargc1a and ACADM were observed in EDL of male mice in response to AdipoRon treatment and a decrease in expression of PDK4 was observed in both gastrocnemius and soleus indicating a shift toward oxidative metabolism in all muscle types. Conversely, these changes at the gene expression level were not observed in the female mice. Overall, AdipoRon treatment induced changes in the relative proportions of oxidative and glycolytic muscle fibers in EDL, gastrocnemius, and soleus; however, the skeletal muscle remodeling response to AdipoRon was muscle type and sex specific. In both sexes, the greatest response to AdipoRon was detected in EDL, which is the more glycolytic of the three muscle groups investigated. These data uncover differences in the underlying biology of skeletal muscle between males and females that may have implications for sarcopenia treatment. Taken together, our studies show that AdipoRon has potential as a therapeutic for sarcopenia in males and although sex dimorphic in its mechanism of action, is likely to also be effective as a treatment for sarcopenia in females.Support or Funding Information1I01BX003846‐01A2
NFkB Mediates Renal Sodium Retention via the Sodium Chloride Cotransporter in Zinc Deficiency‐induced Hypertension
Authors: Murta Cindellynn , Schindele Dylan , Wenegieme Tara-Yesomi , Waite Aston , Naraine Meagan , Sonner Martha , Williams Clintoria 
Published: April 2020

BackgroundZinc deficiency (ZnD) is comorbid with diseases such as kidney disease and diabetes. Individuals in these populations have a higher prevalence of hypertension. Recently, we reported that ZnD promotes hypertension in mice. The blood pressure elevations were accompanied with increased Na+ retention via the renal Sodium Chloride Cotransporter (NCC). Although our published results indicate that zinc plays a critical role in blood pressure and NCC regulation, the mechanisms involved were not investigated.HypothesisSince nuclear factor‐kB (NFκB) mediates ZnD‐induced detrimental effects, we tested the hypothesis that NFκB drives ZnD‐induced NCC upregulation and subsequently renal Na+ retention and hypertension.Experimental DesignTo determine the role of NFκB in ZnD‐induced renal Na+ retention and hypertension, adult male C57Bl/6 mice were fed a ZnD diet (5 weeks) followed by administration of the NFκB inhibitor ‐ caffeic acid phenethyl ester (CAPE; 1 week). Systolic blood pressure and urinary Na+ concentrations were examined. To examine if NFκB mediates ZnD‐induced NCC upregulation, mouse distal convoluted tubule (mDCT) cells were treated with the zinc chelator N, N, N′, N′‐tetrakis(2‐pyridinylmethyl)‐1,2‐ethanediamine (TPEN) ± CAPE, a NFκB inhibitor. After 24 hours, NCC mRNA and protein expressions, as well as activation, were assessed by qRT‐PCR, Western blot and immunofluorescence, respectively.ResultsIn mice, ZnD promoted hypertension and renal Na+ retention. Further, increased NCC expression was accompanied with enhanced NFκB expression in ZnD mice. However, CAPE administration lowered blood pressure and elevated urinary Na+ concentrations. In mDCT cells, TPEN‐induced NCC upregulation was prevented by CAPE treatment.ConclusionsTogether, these results demonstrate that 1) NFκB is a novel NCC regulator and 2) NFκB mediates ZnD‐induced renal Na+ retention and hypertension. These novel findings indicate that ZnD drives renal NFκB activation thereby stimulating NCC‐mediated Na+ retention and promoting hypertension.SignificanceThis study identifies NFκB as a possible pharmacological target to mitigate hypertension.Support or Funding InformationAmerican Heart Association ‐ Scientist Development Grant #16SDG27080009 National Institutes of Health ‐ R21 Exploratory/Development Grant #R21DK119879
Investigation of Factors that Trigger Essential Conformational Changes in FTT258
Authors: Hossain Asif Ali , Johnson R. Jeremy 
Published: April 2020

FTT258 is a close bacterial relative of human acyl protein thioesterase (hAPT), a protein linked to cancer. hAPT removes long chain lipids from key cancer signaling proteins. Removal of these lipids requires their insertion into a pocket within hAPT, which is only exposed after the movement of a flexible loop, a common feature between hAPT and FTT258. However, the causes for the movement of this loop are unknown. I investigated factors that may trigger loop movement in APTs like hAPT and FTT258. In particular, I exposed FTT258 to inhibitors structurally similar to long chain lipids and to membrane‐mimicking surfactants in order to determine if these factors induce loop movement. Loop movement was detected by measuring the change in intrinsic tryptophan fluorescence before and after exposure to these conditions. Ultimately, understanding the factors controlling FTT258 and hAPT function can provide novel mechanisms for inhibiting cancer progression.Support or Funding InformationNSF MCB‐1812971
Genetic ablation of caspase‐2 decreases muscle function in female mice
Authors: Bhattacharya Arunabh , Gonzalez Peter , Valentine Joseph , Hussong Stacey , Martinez Vanessa , Sharma Ramaswamy 
Published: April 2020

Caspase‐2, a cysteine aspartate protease, is an important regulator of apoptosis. We have previously shown that caspase‐2 modulates bone homeostasis. Specifically, we found that 2‐month old female and 5‐month old male Casp2−/− mice exhibited significantly reduced bone mass when compared to wild‐type (WT) mice that continued with aging. Bone is intricately linked to muscle mechanics and function; however, the role of caspase‐2 in skeletal muscle is not clear. This study examined the effect of caspase‐2 on muscle mass and function in 6‐mo‐old WT and Casp2−/− C57BL/6 mice of both sexes. Quantitative nuclear magnetic resonance was used to measure whole‐body lean mass and fat mass. Muscle mass was determined by measuring the mass of quadriceps, gastrocnemius and soleus muscles as well as by measuring cross‐sectional area (CSA) of gastrocnemius muscle. Peak isometric torque of ankle plantarflexors (gastrocnemius, soleus, plantaris) was measured in vivo to determine muscle function. We found decreased body weight and lean mass in both male and female Casp2−/− mice. Muscle mass, CSA and function were not significantly different between male WT and Casp2−/− mice when the data was adjusted for total body lean mass. Similarly, muscle mass and CSA were not different between female Casp2−/− and WT mice. However, significant decrement in muscle function (p < 0.0001) was observed in female Casp2−/− mice compared to female WT mice. We confirmed that our findings in female mice were independent of caspase‐2’s effects on sensorimotor function as there was no difference in sciatic or sural nerve conduction velocity between WT and Casp2−/− mice. Together, these findings suggest a gender‐specific role for caspase‐2 in modulating skeletal muscle function.Support or Funding InformationOwens Foundation
Enzymatic Oxidation of Biological Thiols by MitoNEET
Authors: Skolik Robert A. , Geldenhuys Werner J. , Konkle Mary E. , Menze Michael A. 
Published: April 2020

MitoNEET is a mitochondrial [2Fe‐2S] protein known for its involvement in mitochondrial bioenergetics, iron metabolism, and oxidative stress. The protein has been extensively characterized at the biochemical level since its discovery in 2004, but the mechanisms of physiological function(s) remain unresolved. Two observations seem especially relevant for understanding the physiological function of mitoNEET: (1) under anaerobic conditions in vitro thiol compounds such as glutathione (GSH) and cysteine (Cys) reduce the 2Fe‐2S cluster from the Fe+3Fe+3 to the Fe3+Fe2+ state, and (2) mitoNEET expression levels increase in cells when the glutathione redox balance is shifted towards the oxidized state. We hypothesize that mitoNEET’s in vivo function can be elucidated by bridging these two observations and postulate that mitoNEET is an enzyme responsible for the oxidation of thiol groups on either low molecular‐weight compounds or cysteine residues on target proteins involved in redox signaling. To test this hypothesis, we monitored thiol oxidation by following oxygen consumption rates and demonstrate that mitoNEET accelerates thiol oxidation of cysteine and glutathione (GSH). Four distinct experiments comparing the reactivity of Fe3+ in the form of FeCl3 to mitoNEET demonstrate that the observed thiol oxidation by mitoNEET was not due to free Fe3+contamination. These observations were: (1) rates of cysteine oxidation (8 mM) catalyzed by mitoNEET (1.5 mM) or Fe3+ (1.5 mM) show different optima in the pH range 6.4 to 9.4 and the mitoNEET‐catalyzed reaction is 137% faster at pH 8.4 than the rate observed for Fe3+ alone. (2) Oxidation rates of the nonphysiological compound, n‐acetylcysteine (NAC) by mitoNEET are 181% higher compared to Fe3+ at a pH of 9.0. (3) MitoNEET‐mediated glutathione oxidation remained unaffected by addition of cysteine while oxidation catalyzed by free Fe3+ decreased after addition of cysteine. (4) Dimedone, a probe used to inhibit thiol oxidation from sulfenic acid to sulfinic and sulfonic acid, was 25% more effective at inhibiting cysteine oxidation when free Fe3+ was the catalyst compared to mitoNEET. These results support our hypothesis that mitoNEET possesses an active site which functions to oxidize biological thiols. While the in vivo substrate is currently unknown, we have narrowed down potential candidates to small thiol containing compounds and/or cysteine residues on specific target proteins. We are currently investigating how the enzymatic activity may be regulated by endogenous compounds and through pharmacological compounds targeting mitoNEET.Support or Funding InformationThis work was supported by NSF CHE‐1806266 to M.A.M and M.E.K and UofL Mentored Undergraduate Research and Creative Activities Grant to R.A.S.
Vascular Repair for Prolongation of Life Span of Cadaveric Teaching Specimens
Authors: Morehouse Zachary P. , Laykova Alexandra S. , Fitzsimmons John , Kujjo Loro Lo-Laja 
Published: April 2020

IntroductionCadaveric teaching specimens play a critical role in anatomy education at numerous levels (from undergraduate to doctoral studies, residents, fellows, professors, or visiting scholars/researchers). Due to exposure during teaching and other activities, it is not uncommon for cadaveric structures to sustain damage or normal wear and tear. Damaged or missing structures pose a problem to effective and accurate teaching of anatomy, and ultimately have negative downstream impact on the students’ general anatomic and clinical knowledge base. Additionally, excessive damage to cadavers is one of the leading reasons to retire a specimen from the teaching floor, reducing the number of cadavers available for anatomical study. At Michigan State University (MSU), the Human gross anatomy lab is heavily used for teaching purposes. The cadaveric specimens and body parts are all based on prosected models. Due to this heavy usage it is not uncommon to encounter damaged or missing structures (neurovasculature, muscles, tendons, ligaments, etc) in these specimens. All cadavers prosected at MSU are donors acquired through the university’s Willed Body Program. The generous gift of one’s body to anatomical education is invaluable. Therefore, out of moral obligation and respect to those who have made this gift, the maintenance and prolongation of the teaching lifespan of each donor or body part must be a priority.AimDevelopment of a protocol for anatomically accurate repair of damaged or missing structures of cadaveric specimens, with particular focus on vasculature.MethodsAll torn or cut arteries or veins were repaired using simple surgical techniques. Partially or totally severed vessels were apposed using either 3‐0 or 4‐0 silk sutures and appropriate suture pattern. Grafts of vessels harvested from other areas on the same donor were used to bridge truncated vessels. Similarly, fascia or membranous tissues were harvested and used to mask the repair sites, to prevent further damage and maintain normal anatomic appearances. For small vessels, glue was sufficient to help anastomoses cut ends or close lacerations.ResultsAnatomically accurate vascular repairs were completed on over 20 teaching specimens. Vessels repaired consisted of veins, arteries, lymphatics, and bile ducts. Through these repairs, we were able to restore damaged vascular structures to their appropriate forms and locations. The net outcome is the prolongation of the educational life of each cadaver or body part.Discussion and ConclusionOur protocol enabled us to accurately repair vascular tissues on multiple donors. Hence, with the establishment of this cadaveric vascular repair protocol we will prolong the teaching life for many donors and body parts in labs across all MSU campuses. Additionally, with this protocol in place, we hope to increase and sustain uniform maintenance of donors, ensuring accuracy and availability of human anatomic specimens for all levels of educational activities.
Young Healthy Humans Demonstrate Reduced Executive Function in Moderate Hypoxia
Authors: Buchholtz Zachary A. , Baker Sarah E. , Wiggins Chad C. , Trenerry Max R. , Clifton Haider R. , Holmes David R. , Joyner Michael J. , Curry Timothy B. , Uchida Koji 
Published: April 2020

BackgroundCognitive deficits resulting from mild hypoxia are difficult to quantify and reproduce consistently. The changes in executive function during acute hypoxia are still controversial. The purpose of present study was to assess changes in executive function during acute moderate hypoxia using a continuous performance test (Connors’ Continuous Performance test, CCPT‐II).MethodsNine young, healthy adults (7 women; 28 ± 1 years; BMI: 24.5 ± 3.0 kg·m−2) performed two sets of CCPT‐II during two different conditions: 1) 7 minutes of baseline (fraction of inspired oxygen (FiO2) = 0.21) and 2) 10 minutes of hypoxia (FiO2=0.118). The CCPT‐II is a test of executive cognitive function which requires subjects to strike a key when any letter except the letter X appeared on a computer monitor as quickly and accurately as possible. Reaction time, commission errors (response to X), and omission errors (failure to respond to a letter other than X) were recorded for each 140s of the CCPT‐II block. Arterial oxygen concentration (PaO2) was measured during the last 30sec of baseline and hypoxia from brachial artery catheter samples.ResultsPaO2 was reduced in hypoxia (baseline: 103.1 ± 1.5 mmHg vs. hypoxia: 43.2 ± 1.0 mmHg, P<0.01). During the trials of the CCPT‐II performed during hypoxia, reaction time was lower (i.e. faster) than during baseline (baseline: 451 ± 18 ms. vs. hypoxia: 437 ± 13 ms., P<0.01). Additionally, the number of commission errors was greater in hypoxia (baseline: 1.3 ± 0.6 errors·block−1 vs. hypoxia: 2.1 ± 0.8 errors·block−1, P<0.01). However, the number of omission errors was not different between the two conditions (baseline: 0.4 ± 0.2 errors·block−1 vs. hypoxia: 0.2 ± 0.1 errors·block−1, P=0.92).ConclusionsThe number of commission errors increased and the reaction time decreased during the CCPT‐II test performed in moderate hypoxia compared to baseline, demonstrating a decline in cognitive function during hypoxia. The faster and less accurate responses during hypoxia suggest a suppression of inhibitory pathways in the prefrontal or motor cortex that may contribute to the observed acute reduction in executive cognitive function.Support or Funding InformationThis project was funded by the Office of Naval Research (ONR), grant number N00014‐18‐D‐7001‐TO1.
Cell‐specific heterogeneity of Cx43‐positive gap junctions in the mammalian kidney
Authors: Xu Yan , Hu Junda , Horn John , Bachmann Sebastian 
Published: April 2020

ObjectiveConnexin 43 (Cx43) is a gap junction‐forming protein which mediates the intercellular passage of molecules < 1000 Da. In the kidney, Cx43 was reported in glomerular vessels and mesangium. Own results prompted us to reevaluate the distribution of Cx43 and its phosphorylated form, phospho‐S368‐Cx43 (pCx43), within the different zones of the rat kidney and in cultured fibroblasts in more detail.MethodsCx43 and pCx43 were localized by immunofluorescence in rat kidney sections and cultured human fibroblasts. High‐resolution immunostaining of Cx43 was achieved by ultrastructural immunogold labelling on electron microscopy sections. Double‐labelings with anti‐aquaporin 1 (AQP1), aquaporin 2 (AQP2), zonula occludens‐1 (ZO‐1), and cyclooxygenase‐2 (COX‐2) were conducted to clarify Cx43 distribution in the rat renal medulla. Cultured human fibroblasts served to study intercellular transfer of fluorescent lucifer yellow.ResultsCx43 was distributed in renal arterial and arteriolar endothelia, lymphatic vessel walls, peritubular capillaries, and glomerular compartments. In the interstitium, Cx43 was present as linear or punctate signals of the cell membrane of fibroblasts, in colocalization with pCx43. Cx43‐positive medullary fibroblasts co‐expressed COX‐2. No colocalization was detected between Cx43 and AQP1 or AQP2. Ultrastructural analysis showed Cx43 immunoreactivity at membrane contact zones between fibroblasts and in isolated cell processes of inner medullary interstitium. Cultured fibroblasts showed extensive, punctate Cx43 and pCx43 signals between adjacent cells. Signal was further distributed in non‐junctional areas of plasma membrane, suggesting Cx43 hemichannel functions. Lucifer yellow spread rapidly (10 min) between fibroblasts suggesting intercellular exchange via gap junctions, which was blocked by the gap junctional inhibitor, 18β‐glycyrrhetinic acid.ConclusionsCx43 in rat kidney shows prominent glomerular, vascular, and interstitial distribution, while epithelia, with exception of the podocytes, were negative. Focusing on interstitial fibroblasts, Cx43‐mediated information transfer was demonstrated. A constitutive nature of Cx43 phosphorylation was established in these cells. Our data suggest a cell‐specific heterogeneity of Cx43‐positive gap junctions mediating information exchange among renal cell types.
Simulated Stroke in a Mouse Neuronal Cell Culture Model
Authors: Meyer Luise J. , Eskaf Josephine , Salzman Michele M. , Li Zhu , Riess Matthias L. 
Published: April 2020

INTRODUCTIONDespite many efforts, stroke remains a cause of debilitating illness and death worldwide. The fact that not only ischemia itself, but also the return of blood flow aggravates cellular dysfunction, illustrates a clinical barrier. Hence, catheter‐based interventions, the therapy of ischemic strokes, can add detrimental tissue damage, described as ischemia/reperfusion (I/R) injury. It is therefore crucial to develop potential pharmacological strategies that attenuate reperfusion injury and improve neurological function. Animal in‐vivo and in‐vitro models are vital to determine potential targets for pharmacological therapies. While in‐vivo models better mimic the complexity of the clinical context, in‐vitro studies allow to focus on the pathophysiology and can be performed on individual cell types. This study aimed to establish an in‐vitro stroke model by investigating the effect of simulated I/R injury on mouse brain isolated neurons.METHODSNeurons were plated and grown to confluency. To simulate stroke, cells were then randomized to either control/normoxic (21% O2, 5% CO2, 74% N2) or hypoxic conditions in a hypoxic chamber (0.01% O2, 5% CO2, 94.99% N2) in serum‐ and glucose‐free media. Durations of hypoxia for 2.5, 5 and 10h were compared. After 2h of reoxygenation in regular media and normoxic culture conditions following hypoxia/normoxia, samples were assayed for cell number/viability, cytotoxicity by lactate dehydrogenase (LDH) release and mitochondrial viability. Statistics: Mann‐Whitney Rank Sum Test and regression analysis; alpha=0.05.RESULTSHypoxia significantly impaired cell number/viability after 5 and 10h, whereas 2.5h of hypoxia did not. A large decrease of cell number/viability was observed after 10h of hypoxia compared to 5h and 2.5h. The same observations were made for mitochondrial viability, apart from a slightly lower decrease after 5h hypoxia compared to the cell number/viability. Inverse relations were found for LDH release, except for an already significant increase in cytotoxicity after 2.5h of hypoxia.CONCLUSIONSOur data demonstrate that hypoxic injury in this model is time‐dependent. While 2.5h did not result in sufficient damage and 10h injured neurons too excessively, 5h hypoxia led to a moderate enough damage, still allowing for potential attenuation through protective strategies. Therefore, 5h hypoxia, followed by 2h reperfusion, appears to be a suitable duration for an in‐vitro mouse neuron stroke model to test new treatments.Support or Funding InformationThis work was supported by institutional funds, NIH grant (5R01 HL123227), and a Merit Review Award (I01 BX003482) from the U.S. Department of Veterans Affairs Biomedical Laboratory R&D Service.