bluuebunny/crossref_metadata_2025_split huggingface dataset:
Critical Environmental Limits for Young, Healthy Adults (PSU HEAT)
Authors: Wolf S. T. , Cottle Rachel M. , Vecellio Daniel J. , Kenney W. L. 
Published: May 2022

The average temperature of the Earth has been steadily increasing for decades and is expected to continue increasing throughout the 21st century. Along with the increase in average global temperatures, the frequency, duration, and severity of heat waves have increased. Thus, there is a critical need for research targeted at understanding the specific environmental conditions associated with increased risk of heat‐ and humidity‐related morbidity and mortality.PurposeTo establish critical environmental limits for healthy young adults at two metabolic rates that reflect activities of daily living and light activity. We hypothesized that critical environmental limits would be shifted toward lower combinations of temperature and humidity at higher compared to lower rates of metabolic heat production.MethodsTwenty‐five (12M/13F; 24 ± 4 yrs) subjects were exposed to progressive heat stress in an environmental chamber at two rates of metabolic heat production chosen to represent minimal activity (MinAct) or light ambulation (LightAmb). Progressive heat stress comprised either (1) constant dry‐bulb temperature (Tdb; 36, 38, or 40 °C) and increasing ambient water vapor pressure (Pa; Pcrit trials), or (2) constant Pa (12, 16, or 20 mmHg) and increasing Tdb (Tcrit trials). Chamber Tdb and Pa, and subject gastrointestinal temperature (Tgi), were continuously monitored throughout each trial. After a 30‐min equilibration period, progressive heat stress superseded until subject heat balance could no longer be maintained and a clear rise in Tgi was observed. Each subject was tested during MinAct and LightAmb in 2 or 3 randomized environmental conditions, for a total of 4–6 trials per participant.ResultsBy design, oxygen consumption (V̇O2: 0.46 ± 0.10 vs. 0.80 ± 0.16 L/min; 1.8 ± 0.3 vs. 3.2 ± 0.3 METs), metabolic heat production (82.9 ± 12.5 vs. 133.3 ± 14.8), and sweat rate (142.8 ± 80.2 vs. 230.8 ± 84.9) were lower for MinAct compared to LightAmb (all p < 0.0001). There were no differences in these variables (p ≥ 0.05) among environmental conditions for either MinAct or LightAmb intensities. Higher metabolic heat production (p < 0.001) during LightAmb compared to MinAct trials resulted in significantly lower critical environmental limits across all Pcrit and Tcrit conditions (all p < 0.001).ConclusionsThese data are the first to define critical environmental limits for the maintenance of heat balance in healthy young adults during minimal to light physical activity reflecting activities of daily living and light household tasks. By establishing critical environmental limits in a young, healthy population, the findings of this study will be used as a benchmark for future studies in aged and other vulnerable populations, and can be used to develop guidelines, policy decisions, and evidence‐based alert communications to minimize adverse impacts of extreme heat events.
Implication of GDF15 in the Context of a Renal Adaptation to a Low Potassium Diet
Authors: Lasaad Samia , Walter Christine , Rafael Chloé , Morla Luciana , Crambert Gilles , Cheval Lydie 
Published: May 2022

IntroductionIn the days of hunter‐gatherers, the diet was rich in potassium (K+) and low in salt (NaCl) unlike the current modern western diet, in westernized population, which is low in K+ and rich in NaCl. In the long term, a low‐K+ diet may contribute to the development of diseases such as hypertension or acidosis. The kidney is the key organ in maintaining the electrolyte balance in our body. Indeed, its role is to adjust by different mechanisms the excretion of electrolytes to our daily intake. These mechanisms involve modifications of ion transporters expression and activity, cellular organization and composition of the renal epithelium (proliferation, trans‐differentiation). To face K+ restriction, the kidney adapts its functions to retain K+ by increasing the number of type‐A intercalated cells (ICA). Few years ago, a transcriptomic analysis performed by our laboratory revealed that a growth factor, GDF15, was strongly upregulated in renal collecting ducts of K+ depleted animals. Therefore, we hypothesize that GDF15 may be implicated in the renal adaptation to a low‐K+ diet, in part by promoting ICA proliferation.Material and MethodsC57BL6J mice wild type or knockout for the Gdf15 gene (GDF15‐KO) were used. They were placed under a control or low‐K+ diet for 4 days for 1/ GDF15 expression measurement by RT‐qPCR in kidney or ELISA in urine and plasma 2/ metabolic analysis (urine excretion, muscle mass and K+content) and 3/ assessment of the number of ICA by immunohistochemistry on microdissected distal tubule.ResultsAn increased expression of GDF15 in renal collecting duct, urine and plasma was induced in response to a low‐K+ diet. We showed that under K+ depletion GDF15‐KO mice were unable to induce an increase in the number of ICA, showing a role of this growth factor in the cell plasticity of the collecting duct. Compared to WT mice, GDF15‐KO mice exhibit a delayed renal adaptation to a K+ restriction reflected by a delayed diminution of urinary K+ excretion. This defect induces hypokalemia in GDF15‐KO mice unlike WT mice which remain normokalemic. Interestingly, we have evidence that GDF15 contributes also to the release of intracellular K+ stores in muscles, indicating that this growth factor controls both external and internal K+ balanceConclusionAltogether, these results demonstrate that GDF15 is a key factor in the control of the K+ balance.
Study of the Involvement of Mitochondria in Dent’s Disease Using a Mice Model
Authors: de Combiens Elise , Sakhi Imène , Frachon Nadia , Bignon Yohan , Lourdel Stéphane 
Published: May 2022

Dent's disease is a rare renal tubular disorder characterized by low‐molecular‐weight‐proteinuria, hypercalciuria with nephrocalcinosis or nephrolithiasis, and progressive renal failure. It is frequently associated with inactivating mutations of the CLCN5gene coding for the 2Cl‐/H+ exchanger ClC‐5. In the kidney, ClC‐5 is mainly expressed in early endosomes of proximal tubules (PT) cells where it optimizes the function of the vacuolar H+‐ATPase to ensure proper endocytosis of low‐molecular‐weight‐proteins.To better understand the cellular mechanisms involved in Dent’s disease, we have generated a novel Knock‐In mouse model carrying the ClC‐5 N340K pathogenic mutation. We have previously demonstrated that these mice display similar clinical features to those observed in patients with Dent’s disease. Interestingly, we observed an increase of oxidative stress in their kidney, as evidenced by higher expression of the NADPH oxidase 4, increased H2O2production, and ROS‐related total protein damage in PT cells.Such cellular stress may arise from dysfunctional mitochondria in PT. Here, we therefore investigated the aspect of these organelles in PT cells of WT and N340K 3 month old mice using transmission electron microscopy. Compared to WT mice, mitochondria from mice carrying the N340K mutation exhibited morphologic alterations such as increased roundness, indicating that their function may be altered. Furthermore, to identify potential markers whose urinary excretion could be associated with the progression of Dent’s disease, using mass spectrometry, we performed metabolomic analyses of urine form WT and transgenic mice aged of 4, 7 and 10 months. We demonstrated changes in the excretion of metabolites that are crucial of mitochondrial metabolism (tryptophan, quinolinic acid, malate, oxaloadipate, linolenic acid and butyric acid), suggesting that the NAD+ synthesis pathway, the citric acid cycle, and beta oxidation are affected.The present study shed more light on the pathophysiology of Dent’s disease by suggesting that a mitochondrial dysfunction is involved in this disorder.
Demystifying Cardiac Iron Deficiency in End‐stage Heart Failure
Authors: Zhang Hao , Jamieson Kristi L. , Grenier Justin , Nikhanj Anish , Tang Jack , Wang Faqi , Wang Shaohua , Seidman Jonathan , Seidman Christine , Thompson Richard , Seubert John , Oudit Gavin 
Published: May 2022

BackgroundCardiac iron depletion (CID) in heart failure (HF) remains largely unexplored regarding its prevalence, pathogenesis, and impact on the failing hearts. Hypotheses: We anticipate that iron‐deficient failing hearts will demonstrate defective iron regulatory pathways, whereby the HF progression is markedly aggravated by the mitochondrial redox imbalance.PurposeWe aim to establish CID’s defining criterion, recapitulate its pathophysiological role, and evaluate the applicability of monitoring it non‐invasively in HF.MethodsBiventricular myocardial iron levels were measured in both failing (n=138) and non‐failing control (NFC, n=46) explanted human hearts. Clinical phenotyping was complemented with comprehensive assessment of myocardial remodeling and mitochondrial functional profiles, including metabolism, respiration, and oxidative stress. Heart iron status was further investigated by cardiac magnetic resonance (CMR) imaging.ResultsTissue iron content in the left ventricle (LV) was significantly lower in HF versus NFC [121.4 (88.1‐150.3) vs. 137.4 (109.2‐165.9) μg/g dry weight], which was absent in the right ventricle (RV). With a priori cutoff of 86.1 μg/g d.w. in LV, we identified 23% of HF patients with CID (HF‐CID) associated with higher NYHA class and worsened LV function. Respiratory chain and Krebs cycle enzymatic activities were suppressed and strongly correlated with depleted iron stores in HF‐CID hearts. Defenses against oxidative stress were severely impaired in association with worsened adverse remodeling in iron‐deficient hearts. Mechanistically, iron uptake pathways were impeded in HF‐CID, while transmembrane fraction of ferroportin positively correlated with CID. CMR with T2* effectively captured myocardial iron levels in failing hearts.ConclusionsCID is highly prevalent in advanced human HF and exacerbates pathological remodeling in HF driven primarily by dysfunctional mitochondria and increased oxidative stress in the LV. CMR demonstrates clinical potential to non‐invasively monitor CID.
Decoding Medication Tradenames; an innovative Method for Top 200 medications in Didactic & Experiential Courses
Authors: Elsobky Yasmin , Mente Welly , Kreys Eugene , Mohamed Islam 
Published: May 2022

ObjectiveTo investigate whether decoding of top 200 medication tradenames can result in improving pharmacy students’ performance in IPPE‐didactic & experiential courses. For ex: Macrobid®; provides an elegant explanation of (MACRO) size crystal form of (Macrodantin) designed for slower absorption & less excretion, hence, used twice daily (BID).MethodsAn educational intervention of decoded tradenames (explanation of techniques used in top 200 tradenames) was implemented using Quizlet & summary‐tables before the summative final exam in a first‐year didactic IPPE course. Aggregate de‐identified students’ scores were used for blinded‐paired statistical‐analyses. A Likert‐scale‐surveys was used for evaluating students’ quality of learning experience after both the IPPE‐didactic and experiential rotations courses.ResultsIn aggregate analyses from Fall 2019‐2020; paired data analyses using Wilcoxon test showed a statistically significant increase in average students’ performance from 70.6% +/‐ 18.9% in formative to 80.5% +/‐ 23.5% in summative assessments after the intervention in control questions involving tradenames without rational explanation (p‐value<0.001). Whereas, in questions involving tradenames that have rational explanations, students’ performance increased from an average of 58.0%+/‐28.3% before the intervention, to 75.9%+/‐22.2% afterwards, which represents a net significant difference of 8.1%+/‐39.8% between question groups (p‐value0.009) (n= 169 students). In addition, at least 80% of students reported that decoding tradenames can help them to retain key medications features & connect it to generic names during didactic course, hence, provide better medication recommendations, & make less potential medication errors during their experiential rotation (n=72/94 students).ConclusionsSupplementing pharmacy curricula with the art & science of formulating medication tradenames can improve students’ academic performance in didactic courses. Furthermore, it can also improve the resulting quality of healthcare services future pharmacists provide during their experiential education.
Elucidating the Mechanisms of CaMKII‐CaMKAP Interactions
Authors: Quay Juliana , Gonçalves Michael , Yang Qian , Colbran Roger 
Published: May 2022

Dynamic changes of intracellular calcium ion (Ca2+) concentrations are critical signaling mechanisms in all cells and organisms, and Ca2+ oscillations must be precisely decoded by intracellular signaling molecules, such as the ubiquitous Ca2+/calmodulin‐dependent protein kinase II (CaMKII). Four mammalian CaMKII genes encode diverse alternative mRNA splice variants, which are thought to be targeted to different subcellular compartments to regulate numerous cell responses (exocytosis, gene expression, cell cycle). Our lab hypothesized that the localization, activity, and biological functions of CaMKII are precisely modulated by CaMKII‐associated proteins (CaMKAPs), and we have detected over 100 CaMKAPs associated with brain CaMKII holoenzymes. Some CaMKII‐CaMKAP interactions are critical for normal physiological function. CaMKIIδ binding to the L‐type Ca2+ channel (LTCC) b2a subunit is essential for cardiac function1, and binding of neuronal CaMKII to the GluN2B subunit of the NMDA‐type glutamate receptor is necessary for synaptic plasticity2. While b2a, GluN2B and most other CaMKAPs preferentially interact with activated CaMKII, the exact molecular mechanisms for these interactions, and their physiological roles, have yet to be determined. Several residues in the catalytic domain of CaMKII have been implicated in CaMKAP binding. Previous mutagenesis studies from our lab indicated that mutation of valine 102 (V102) to glutamate disrupts CaMKII binding to LTCC α1 subunits, but not to b2a, GluN2B, or densin, and also disrupts neuronal excitation‐transcription coupling3. Additionally, a naturally‐occurring CaMKIIα Glu183Val mutation linked to autism spectrum disorder and intellectual disability disrupted interactions with all CaMKAPs tested4. To further probe the molecular basis of CaMKII‐CaMKAP interactions, we are exploiting available structural information to design additional CaMKII catalytic domain mutations, and then test their effect on CaMKII‐CaMKAP interactions, as well as CaMKII activity toward multiple substrates. We are also examining the impact of additional human CaMKII mutations. Initial studies indicate that some CaMKII mutations differentially affect binding to various CaMKAPs, CaMKII autophosphorylation, and phosphorylation of a representative substrate, the GluA1 subunit of AMPA‐type glutamate receptors. Our ongoing studies are further exploring the impact of these CaMKII mutations. Expanding our knowledge of mechanisms underlying CaMKII‐CaMKAP interactions is required to better understand CaMKII biology, the role of CaMKAPs, and the molecular basis of Ca2+signaling.

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Characterization of the Nickel‐inserting Cyclometallase LarC from Moorella thermoacetica and Identification of a CMPylated Reaction Intermediate
Authors: Turmo Aiko , Sui Dexin , Kim Kelly H. , Hu Jian , Hausinger Robert P. 
Published: May 2022

The nickel‐pincer nucleotide (NPN) cofactor is required for lactate racemase (LarA) activity1, and LarB, LarE, and LarC are needed to generate this coenzyme2. LarC catalyzes the last step of the biosynthesis pathway by inserting nickel into pyridinium‐3,5‐dithiocarboxylic acid mononucleotide (P2TMN), resulting in the mature NPN cofactor3. Previously, LarC from Lactobacillus plantarum was shown to be a CTP‐dependent, single‐turnover nickel insertase or cyclometallase, but a structure was only obtained for its C‐terminal domain and its reaction mechanism was not identified. We characterized LarC from Moorella thermoacetica(LarCMt) and identified a novel reaction intermediate in which the precursor P2TMN is CMPylated. We propose that LarCMt uses CTP to generate the CMP‐P2TMN species that is properly positioned in the active site for nickel insertion, analogous to the molybdenum insertion step during molybdenum cofactor biosynthesis4. LarCMt variants were characterized to further elucidate the mechanism of the transient CMPylation process. Additionally, we generated preliminary structural data for the full‐length LarCMt through cryo‐electron microscopy. Our results highlight the role of CTP in the nickel insertion reaction and provide a better structural and mechanistic understanding of the LarC reaction.1. Desguin, B. et al. A tethered niacin‐derived pincer complex with a nickel‐carbon bond in lactate racemase. Science. 349, 66–69 (2015).2. Desguin, B. et al. Lactate racemase is a nickel‐dependent enzyme activated by a widespread maturation system. Nat. Commun. 5, 3615 (2014).3. Desguin, B. et al. Biosynthesis of the nickel‐pincer nucleotide cofactor of lactate racemase requires a CTP‐dependent cyclometallase. J. Biol. Chem. 293, 12303–12317 (2018).4. Llamas, A., Mendel, R. R. & Schwarz, G. Synthesis of adenylated molybdopterin: An essential step for molybdenum insertion. J. Biol. Chem. 279, 55241–55246 (2004).
Assessing the effects of COVID‐19‐induced hypoxia and ACE2 signaling on the human blood‐brain barrier in‐vitro
Authors: Pervaiz Iqra , Varahachalam Sree Pooja , Al‐Ahmad Abraham J. 
Published: May 2022

IntroductionCoronavirus disease 2019 (COVID‐19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV2). The portal of entry for the virus is peptidase ACE2, a major key player of the renin‐angiotensin‐aldosterone system (RAAS), resulting in severe lung injury. Although COVID‐19 mainly manifests as an acute respiratory distress syndrome (ARDS), there is increasing evidence of neurological symptoms in patients infected by COVID‐19. Yet, there is limited understanding of how COVID‐19 impacts the central nervous system (CNS). We speculate that such neurological symptoms maybe a consequence of a dysfunction of the blood‐brain barrier (BBB) with our central hypothesis that the neurological effects of SARS CoV‐2 are driven by chronic hypoxic stress‐impaired ACE2 at the BBB.MethodsAn in‐vitro human induced pluripotent stem cells (hiPSCs) BBB model was used in the study. Such model was exposed to various levels of hypoxia (1,5 and 10%) for up to 24 hours. In addition, normoxic cells were treated with Angiotensin II (AngII) or Angiotensin 1‐7 (degradation by product of AngII by ACE2). Changes in the barrier function was assessed using TEER, permeability to fluorescein and tight junction staining. Changes in ACE2 and MasR expression was assessed by immunofluorescence, whereas ACE2 shedding and HIF‐1 alpha expression was assessed by ELISA.ResultsMild (10%) hypoxia was sufficient to induce the loss of barrier function. Secretion of ACE2 under hypoxia followed a biphasic pattern, with highest levels at 5% and 10%. Ang II and Ang1‐7 had little effect on the barrier function under normoxic condition. The hypoxic exposure induced shedding of the membrane bound ACE2 and molecular mechanism of hypoxic exposure in regulation of ACE2 occurs in a HIF1α‐ dependent manner.DiscussionOur preliminary data suggest that our human model of the BBB responds to hypoxia and express critical components of RAAS. Both ACE2 and MasR negatively respond to mild hypoxia followed by a decreased barrier function with no changes in tight junction complex. Such loss was correlated with increased ACE2 shedding in HIF1α‐ dependent manner. We are currently investigating role of Ang 1‐7 in rescuing barrier function under hypoxic stress.
Revealing novel molecular pathways in exosome production and pathological effects in the context of autophagy deficiency
Authors: Liu Gang , Ma Michelle , Yin Xiao‐Ming 
Published: May 2022

Extracellular vehicles (EVs) are defined as membrane‐surrounded, nanometer‐sized vesicles released by cells into the extracellular space in a highly regulated manner. Exosomes, a subclass of EVs with an average size of 40 to 160 nm in diameter, play critical roles in cell‐cell communications and in pathogenesis of many diseases, including liver diseases. However, the molecular mechanism of exosome production in specific disease scenario is not known. Here we use a mouse model of liver injury caused by autophagy deficiency to investigate the induction mechanism and the role of exosome in the pathogenesis.We found that there was an increased serum presence of liver‐specific exosomes when hepatic autophagy function was disabled through nanoparticle tracking analysis (NTA). These EVs had the average size of 100 nm, and expressed hepatocyte‐derived TSG101 and CYP2E1. Notably we defined specific markers that had not been reported before, such as Syntenin‐2, which is a Syndecan‐binding protein. This molecule is closely related to the formation of multivesicular bodies (MVBs), which is considered as the precursor of EVs. Exosome production can be increased or decreased by Syntenin‐2 overexpression or knockdown, respectively, indicating that this molecule is crucial for the exosome production. In addition, increased expression of Syntenin‐2 and increased production of exosomes in autophagy deficient mice were reversed by co‐deletion of an anti‐oxidative gene, Nrf2. Thus, we have defined a new pathway from Nrf2 to Syntenin‐2 in controlling the production of a liver specific exosome in the context of autophagy deficiency.To under the pathological role of these exosomes, blood EVs isolated from autophagy deficient mice were incubated with macrophages derived from the bone marrows (BMDM), which are recruited to the liver and contribute to the hepatic inflammation. We found that BMDM could effectively internalize the exosomes and are then activated for the production of a number of pro‐inflammatory genes compared to BMDM co‐cultured with exosomes isolated from wild type mice. Sequence profiling of miRNAs carried by these exosomes identified miR‐3072‐3p that can stimulate BMDM to upregulate the expression of the pro‐inflammatory genes, suggesting that these cells can be activated by the exosomes via miRNA‐mediated signaling.In summary, our work has revealed novel molecular components in promoting the production of liver‐specific exosomes under autophagy deficiency, which in turn enhances the inflammatory response in the liver through a unique miRNA‐mediated pathway.