bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lactate Administration Increases Skeletal Muscle Synthesis in Mice
Authors: Kyun Sunghwan , Jang Inkwon , Hwang Deunsol , Park Hun‐Young , Kim Jisu , Lim Kiwon 
Published: May 2022

PurposeLactate, secreted by skeletal muscle during exercise, had been known as fatigue substance. However, several physiological roles of lactate have been revealed in the last decades, and previous studies reported that lactate treatment increased protein synthesis factors in skeletal muscle. Nevertheless, underlying molecular mechanisms of exogenous lactate on protein synthesis and degradation remain unknown, and there was no study that confirm long‐term lactate administration with exercise training. Therefore, the purpose of study is to investigate the effect of long‐term exogenous lactate administration and lactate administration with exercise training on the skeletal muscle synthesis and degradation.Methods32 mice were randomly divided into four groups: sedentary + saline (Sed/Con), sedentary + lactate (Sed/Lac), exercise training + saline (Ex/Con), and Exercise training + lactate (Ex/Lac). Exercise training (VO2max 70%) and lactate administration (3 g/kg sodium lactate) performed 5 days a week. The timing of lactate administration was immediately after every exercise training, and saline administration groups were given same volume of saline as lactate. After 5 weeks, mice were sacrificed and immediately obtained skeletal muscle and blood. To confirm the effect of lactate on protein synthesis (IGF receptor, Akt and mTOR phosphate/total) and degradation (MuRF1, MAFbx1, FOXO1), mRNA and protein expression analyzed respectively plantaris and extensor digitorum longus. Blood parameters of lactate, insulin, IGF1, and glucose were measured.ResultsSkeletal muscle weight tended to higher Sed/Lac than Sed/Con, but Sed/Lac had significantly supplement effects compared to Sed/Con in only gastrocnemius weight (p = .000). Blood IGF1 showed that Sed/Lac was significantly lower than Sed/Con (p = .039) and Ex/Lac (p = .007). mRNA of IGF receptor had only exercise effects (p = .000). mRNA of Akt and mTOR showed that Sed/Lac was significantly higher than Sed/Con (respectively, p = .000 and p = .043). Protein expression of MuRF1, Sed/Lac was significantly lower than Sed/Con (p = .046), but exercise training effects was found saline groups (Sed/Con vs Ex/Con; p = .001).ConclusionThis study showed that long‐term lactate administration had positive effects on Akt / mTOR and MuRF1. Especially, it was confirmed that long‐term lactate administration increased skeletal muscle mass in mice. Hence, we suggest that long‐term lactate administration increases skeletal muscle synthesis and that lactate administration can be used as supplement for sarcopenia. Nevertheless, this study did not confirm synergistic effects of lactate administration with exercise training. It is suggested that post‐exercise lactate administration, unlike lactate administration at rest state, affects energy metabolism rather skeletal muscle synthesis. Therefore, future study would be necessary to investigate lactate administration timing with exercise training.
Methionine‐aromatic Interaction as a Tool to Enhance Protein Stability
Authors: Chatterjee Kiran Sankar , Das Ranabir 
Published: May 2022

Nonbonded aromatic interactions play a significant role in stabilizing a folded protein structure(1, 2). Apart from well‐studied aromatic‐aromatic interactions in proteins, preferential proximity of sulfur containing cysteine and methionine sidechains and aromatic rings is also observed in protein hydrophobic cores and at the interfaces of protein‐protein complexes. Methionine‐aromatic motifs are examples of such S‐aromatic motifs that provide additional stabilization at a longer distance range over pure hydrophobic interactions(3). Although the idea of preferential association of aromatic amino acids has been successfully implemented for de novo design of peptides and proteins, the additional stability provided by met‐aromatic motif over pure hydrophobic interaction and its potential significance in designing a stabler protein fold has not been examined before. The present work shows the relevance of S‐aromatic interaction in increasing thermodynamic stability of a protein fold using Small Ubiquitin‐Like Modifier (SUMO) protein. We found that a highly conserved methionine‐phenylalanine motif in the core is a unique signature of SUMO but absent in other homologous Ubiquitin‐like (Ubl) protein folds. Using biophysical measurements and solution NMR based experiments, we found that the specific ‘up’ conformation between the methionine‐phenylalanine pair is critical to SUMO’s β‐grasp fold stability and its function(4). Given the additional stability provided by met‐aromatic motif over classical hydrophobic interaction, we engineered new S‐aromatic motifs in SUMO by replacing phenylalanine with other naturally occurring aromatic amino acids. Combining all atom MD simulations and solution NMR studies, we identify the energetically preferred interaction geometry of different met‐aromatic motifs inside the core. We found that the engineered SUMOs with increasing S‐aromatic interaction strength enhances the overall protein stability. Overall, our results reveal the potential role of S‐aromatic interactions as a design tool in enhancing thermodynamic stability of a protein fold.References1. Chatterjee, K. S., Tripathi, V., and Das, R. (2019) A conserved and buried edge‐to‐face aromatic interaction in small ubiquitin‐like modifier (SUMO) has a role in SUMO stability and function. J. Biol. Chem. 294, 6772–67842. Serrano, L., Bycroft, M., and Fersht, A. R. (1991) Aromatic‐aromatic interactions and protein stability. J. Mol. Biol. 218, 465–4753. Valley, C. C., Cembran, A., Perlmutter, J. D., Lewis, A. K., Labello, N. P., Gao, J., and Sachs, J. N. (2012) The Methionine‐aromatic Motif Plays a Unique Role in Stabilizing Protein Structure. J. Biol. Chem. 287, 34979–349914. Chatterjee, K. S., and Das, R. (2021) An “up” oriented methionine‐aromatic structural motif in SUMO is critical for its stability and activity. J. Biol. Chem. 297, 100970
Microelectrodes for measurement of intracellular [K+] and [Na+]in the choroid plexus epithelium and cerebrospinal fluid
Authors: Berenji Ardestani Simin , Matchkov Vladimir V. , Praetorius Jeppe 
Published: May 2022

The choroid plexus epithelium (CPE) has recently gained increasing interest as a potential target tissue to manipulating cerebrospinal fluid (CSF) production (1). It is therefore crucial to identify the basolateral Na+ transport mechanisms that are involved in CSF secretion, as it would be accessible from the blood side and thereby hold promise for pharmacological intervention. The sodium‐bicarbonate transporter Ncbe has been identified as a basolateral Na+ importer in the CPE (2,3). Currently, there is no direct intracellular cation measurements in choroid plexus and this information is needed to establish Ncbe as the main basolateral Na+ importer. The aim of this project is to measure the [Na+] and [K+] concentration in CSF and in CPE in vivo with double‐barreled microelectrodes. Ion selective double‐barreled microelectrodes are the tool to measure directly the different ion concentrations. The reference barreled was filled with 500 mM KCl solution and the tip of ion sensitive barrel was filled with Na+ or K+ionophore and then backfilled with KCl solution. In this ongoing project, we were able to estimate extracellular [K+] to 4.08 ± 1.06 mM in CSF of mice in vivo (n=7). The study is in progress.References1: Damkier HH, Brown PD, Praetorius J. Cerebrospinal fluid secretion by the choroid plexus. Physiol Rev. 2013;93:1847‐92.2: Praetorius J, Nejsum LN, Nielsen S. A SLC4A10 gene product maps selectively to the basolateral plasma membrane of choroid plexus epithelial cells. Am J Physiol Cell Physiol. 2004;286:C601‐10.3: Damkier HH, Nielsen S, Praetorius J. Molecular expression of SLC4‐derived Na+‐dependent anion transporters in selected human tissues. Am J Physiol Regul Integr Comp Physiol. 2007;293:R2136‐46.
Amelioration of Cardiac Autonomic Dysfunction Mitigates Perivascular and Perirenal Adipose Inflammation and Cardiorenal Involvement in Prediabetes
Authors: El‐Yazbi Ahmed F. , Hammoud Safaa , Alzaim Ibrahim F. , Bekdash Amira F. , Mougharbil Nahed , Itani Hana F. 
Published: May 2022

BackgroundEarly metabolic impairment is associated with significant cardiorenal risk. Specifically, subtle serum insulin and lipids changes in prediabetes trigger cardioautonomic and renovascular deterioration. Interestingly, data from our laboratory suggest that these insidious alterations are triggered by perirenal and perivascular adipose inflammation in response to hypoxia evoked by a localized increase in uncoupling protein1 (UCP1) expression and activity. This affects the adjacent organs in a paracrine manner.HypothesisIncreased UCP1 expression is triggered by sympathetic stimulation. The sympathovagal imbalance in early metabolic dysfunction underlies the observed localized adipose pool involvement. Pharmacological interventions to offset the sympathetic predominance should prevent increased UCP1 expression and inflammation, and reverse cardiorenal manifestations.MethodsA non‐obese prediabetic rat model was induced by twelve weeks of hypercaloric feeding. Moxonidine and galantamine were administered orally at daily doses of 2.4 mg/Kg and 4 mg/Kg for the last two weeks of feeding to reduce and facilitate sympathetic and parasympathetic discharge, respectively. Baroreflex sensitivity and renovascular reactivity were assessed by invasive hemodynamics and in isolated perfused kidneys, respectively. Adipose tissue T Cell distribution and macrophage polarization were examined by flow cytometry.ResultsCorrecting the autonomic imbalance in prediabetic rats with either moxonidine or galantamine restored cardioautonomic and renovascular activity to those observed in control rats. Although prediabetic rats showed an increased oxidative stress and proinflammatory cytokine production in both adipose pools, no change in T Cell population distribution was observed. However, the increased M1/M2 macrophage polarization profile observed in prediabetic rats was reversed by either drug treatment. This was associated with a normalization of UCP1 expression and hypoxic status.ConclusionsPharmacological interventions to reverse sympathetic predominance could be of therapeutic value treating perivascular and perirenal adipose inflammation that cause early cardiorenal manifestations of prediabetes.
Different Murine Models of Kidney Injury Reveal a Common Pattern of Dysregulation within the Polyamine System in Favour of its Catabolic Pathways
Authors: Sieckmann Tobias , Ögel Neslihan , Kelterborn Simon , Boivin Felix J. , Schley Gunnar , Fähling Michael , Ashraf Muhammad imtiaz , Reichel Martin , Vigolo Emilia , Hartner Andrea , Knauf Felix , Rosenberger Christian , Aigner Felix , Smidt‐Ott Kai , Scholz Holger , Kirschner Karin M. 
Published: May 2022

The polyamines putrescine, spermidine and spermine are organic polycations that regulate many cell functions including proliferation and differentiation. It is known that certain genes of the polyamine system are dysregulated after kidney ischemia reperfusion injury. Here we examined the hypothesis that different forms of acute and chronic kidney injury lead to similar changes in the expression patterns of the polyamine system.In different models of acute and chronic kidney injury expression of genes involved in polyamine homeostasis were analyzed by RT‐qPCR and RNAScope. In these models, expression of catabolic enzymes (Aoc1 and Sat1) was upregulated, and the anabolic enzymes (Odc1, Sms) were downregulated. The putrescine‐degrading enzyme AOC1 exhibits the most striking changes. Interestingly, it can act together with ODC1 as gatekeepers of the polyamine system. The detected increase of Aoc1 takes place in the injured but regenerating proximal tubules. As a screening for stimuli of increased Aoc1 expression, we used mouse embryonic kidney explants. Here we observed changes of Aoc1expression under hypoxia and hyperosmotic conditions. These changes were further examined in mouse models of hypoxia. However, in vivo, hypoxia did not lead to changes of Aoc1 expression. Hyperosmolarity was confirmed as a stimulus by using the kidney cell lines M15 and 209/MDCT as well as cultured primary proximal tubules. Using reporter gene and RNA‐stability assays, we could show that the increase in Aoc1 expression is based on mRNA‐stabilization and transcriptional activation of one certain isoform. The activated isoform contains an additional set of 22 amino acids N‐terminally that lead to an altered subcellular localization.In conclusion, different models of kidney injury exhibit a similar pattern of dysregulation of the polyamine system with the most striking change being the upregulation of Aoc1 in proximal tubules. Using hyperosmolarity as a stimulus, we provide first insights into the regulation of Aoc1 under harmful conditions.
Indole‐3‐propionic Acid, Bacterial Metabolite of Tryptophan, Increases Blood Pressure in Normotensive and Hypertensive Rats
Authors: Konopelski Piotr , Chabowski Dawid , Aleksandrowicz Marta , Kozniewska Ewa , Podsadni Piotr , Szczepanska Agnieszka , Ufnal Marcin 
Published: May 2022

Tryptophan is an exogenous amino acid, undergoing complex metabolism in mammals, including formation of gut microbiota‐derived metabolites. Tryptophan was proven to increase blood pressure in rats and humans, however; it has not been profoundly investigated, whether its impact on cardiovascular system might be due to the action of microbiota derived indoles, especially indole‐3‐propionic acid (IPA).Acute hemodynamic experiments were performed on 12‐week‐old Wistar‐Kyoto (WKY) and 16‐week‐old Spontaneously‐Hypertensive (SHR) male anesthetized rats. Mean arterial blood pressure (MABP) and heart rate (HR) were evaluated for 120 minutes after intravenous infusion of 10% DMSO (Vehicle) and IPA in increasing doses (1.6‐53 µM/kg body wt). In separate series of experiments impact of IPA on vascular contractility was evaluated in ex vivo experiments performed on mesenteric resistance arteries (MRAs).IPA increased significantly blood pressure in normotensive and hypertensive rats. In normotensive rats at highest dose IPA revealed less pronounced hypertensive effect, accompanied by decrease in HR. This effect was not observed in hypertensive rats, where IPA increased MABP in dose dependent matter, with concomitant tachycardic response. In ex vivo experiments IPA increased contractility of endothelium‐denuded MRAs and reduced acetylcholine‐dependent dilatation of MRAs.Our study suggest, that IPA takes part in regulation of blood pressure, by revealing hypertensive and vasoconstrictive activity. These effects are in line with actions of its precursor tryptophan, suggesting important role of bacterial metabolism of tryptophan in its cardiovascular effects.
Intercellular Ca2+ waves propagate by regenerative IP3‐induced IP3 release
Authors: Buckley Charlotte , Zhang Xun , Lee Matthew , Wilson Calum , McCarron John G. 
Published: May 2022

The endothelium is a sheet of highly‐specialised cells that line every blood vessel. Endothelial cells detect, integrate and respond to information from numerous signals, passing this information to neighbouring endothelial cells via intercellular communication to coordinate vascular contractility, inflammation and exchange of products between the blood and surrounding tissues. A significant form of intercellular communication occurs by travelling spatial gradients of Ca2+ (‘Ca2+ waves’) that move between cells. While the underlying mechanisms are not understood, Ca2+ and IP3 diffusion through gap junctions are each proposed to underlie Ca2+ wave propagation in the endothelium. Our results show that IP3, but not Ca2+ or gap junctions, is required for Ca2+ wave propagation.To investigate the mechanisms underlying endothelial signal propagation, second order mesenteric arteries were dissected from rats, pinned out in an en face configuration and Ca2+ signals measured using Cal‐520 (5μM). Localised photorelease of caged‐IP3 (5μM) generated rapid rises in endothelial Ca2+ at the site of photo‐activation. The Ca2+ rise subsequently propagated across cells outside the photolysis site. The propagated Ca2+ rise reflects cell‐cell communication since no uncaging occurred outside the photolysis site.To investigate the contribution of Ca2+ to signal propagation, Ca2+ buffering was spatiotemporally controlled using local photoactivation of the membrane permeant Ca2+ buffer, Diazo‐2. Release of the Ca2+ buffer prevented signal propagation within the uncaging region alone; signal propagation still occurred outside the uncaging area. This result suggests that IP3, but not Ca2+, underlies wave propagation. Supportive evidence for this conclusion was provided by photolysis of caged Ca2+(NP‐EGTA AM, 5μM). Photorelease of caged Ca2+ generated a Ca2+ rise that remained localised to the uncaging region and did not propagate outside the photolysis site, even with progressively increased Ca2+ loads. To verify these results, ACh (1μM) or ionomycin (10μM) were applied to restricted populations of cells by pressure ejection from a puffer pipette. A comparable Ca2+ rise was generated in each case, however the ACh generated a substantial Ca2+ wave that propagated upstream of the activated cells while the Ca2+ rise from ionomycin did not. These results suggest that Ca2+ is not responsible for propagating Ca2+ waves in the endothelium. The data also questions the involvement of gap junctions in wave transmission. If gap junctions were present and open, the Ca2+ rise generated by ionomycin would have been expected to diffuse to neighboring cells. This was not observed. Furthermore, the gap junction blockers gap27 and 18αGA, while successful in blocking FRAP, did not inhibit wave propagation. Together, these results suggest that IP3 is essential for Ca2+ wave propagation, but Ca2+ or gap junctions are not.
Maternal Exercise May Improve Metabolic Outcomes in Offspring in Mice
Authors: Prentice Danielle M. , Bingaman Sarah , Ural Serdar , Browning Kirsteen , Arnold Amy 
Published: May 2022

ObjectiveIt is well recognized in both human epidemiological and animal studies that the maternal in utero environment has significant effects on development of offspring. This includes sedentary lifestyle, which has been linked to developmental programming of metabolic dysfunction. The aim of this study is to investigate metabolic outcomes in offspring of sedentary mice versus mice that exercised in pregnancy.Study DesignC57BL/6J female mice were placed on a control diet and allocated to sedentary versus exercise cages at 17 weeks of age. Exercise cages included a voluntary running wheel, with daily exercise measured via activity trackers. Mice were allowed to exercise for 2 weeks prior to breeding and throughout weaning. Offspring underwent body composition measurement and insulin and glucose tolerance tests at 6 weeks of age. At 14‐16 weeks of age, body composition was reassessed and mice were euthanized for tissue collection. Outcomes were analyzed between sedentary (SED) and exercise (EX) offspring using an unpaired t‐test, with p<0.05 considered significant.ResultsWe studied metabolic function in 10 SED and 9 EX offspring. Insulin sensitivity, measured as the area under the curve for the decrease in glucose over time in response to insulin, tended to be improved in EX versus SED offspring (‐188 vs. 2991; p=0.062), with no difference in fasting glucose levels or glucose tolerance. While body mass was similar at end of study (23.4 EX vs. 23.1 SED; p=0.83), the percentage of subcutaneous white adipose tissue tended to be lower (0.94 EX vs. 1.67 SED; p=0.054) and brown adipose tissue was higher (0.57 EX vs. vs 0.30 SED; p<0.001) in EX offspring.ConclusionsThese data suggest that maternal exercise may improve insulin sensitivity in offspring even under normal diet conditions. Further, despite similar body mass, offspring from mice that exercised during pregnancy had a shift in adipose depot composition with lower white adipose and higher brown adipose tissue. This change in body composition may have important implications for energy metabolism and is an important area of future study.
Dietary Bioflavanol Supplementation Does Not Improve Cold‐Induced Vasodilation in Healthy Adults
Authors: Greenfield Andrew , Yurkevicius Beau , Castellani John , Alba Billie 
Published: May 2022

BackgroundCold‐induced vasodilation (CIVD) is a cyclical rise in blood flow to glabrous skin that occurs during cold exposure of the extremities. Nitric oxide (NO) is a proposed mediator of the CIVD response through active vasodilation and/or withdrawal of sympathetic vascular smooth muscle tone. Dietary flavanols augment bioavailable NO by upregulating NO synthase, the main source of NO in the vasculature, and by enhancing removal of reactive oxygen species that are known to breakdown NO. Although acute dietary flavanol intake has been shown to augment skin blood flow, at least in part through increased NO, no studies have examined the impact of flavanol intake on skin perfusion during cold exposure. Improving skin blood flow to the extremities may enhance manual dexterity and reduce the risk of peripheral cold injury, benefits pertinent to warfighters or other populations that spend time in cold environments.PurposeTo examine the effect of high‐dose flavanol supplementation on CIVD. We hypothesized that acute and 8‐day flavanol supplementation would augment CIVD during single‐digit cold water immersion.MethodsEleven healthy adults (24±6 yrs; 10M/1F) ingested cocoa‐based flavanols (FLV; 900 mg/d) or caffeine and theobromine‐matched placebo (PLA) for 8 days in a double‐blind, randomized, crossover design. On Days 1 and 8, CIVD was assessed 2 hours after treatment ingestion. Subjects immersed their middle finger in warm water (42°C) for 15 minutes before cold water immersion (4°C) for 30 min, during which nail bed and finger pad skin temperature were measured continuously.ResultsFlavanol ingestion had no effect (all P > 0.05) on CIVD event frequency (Day 1, FLV: 3±2 vs. PLA: 3±2; Day 8, FLV: 3±2 vs. PLA: 3±1) or amplitude (Day 1, FLV: 4.3±1.7 vs. PLA: 4.9±2.6 °C; Day 8, FLV: 3.9±1.9 vs. PLA: 3.9±2.0 °C) in the finger pad following acute or 8‐day supplementation. Furthermore, average (Day 1, FLV: 9.2±1.5 vs. PLA: 9.2±1.8 °C; Day 8, FLV: 8.3±1.7 vs. PLA: 8.9±1.9 °C), maximum (Day 1, FLV: 11.9±3.0 vs. PLA: 11.2±2.3 °C; Day 8, FLV: 10.1±1.9 vs. PLA: 10.6±2.3 °C), and minimum (Day 1, FLV: 6.2±1.3 vs. PLA: 6.0±1.5 °C; Day 8, FLV: 5.8±1.8 vs. PLA: 6.2±1.7 °C) finger pad temperatures during cold water immersion were not different (all P > 0.05) between treatments on Day 1 or Day 8 of supplementation. Similarly, no differences (all P > 0.05) in CIVD parameters were observed in the nail bed following acute or 8‐day supplementation.ConclusionDietary ingestion of cocoa‐based flavanols does not improve the CIVD response to single‐digit cold water immersion.