bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cardiovascular reactivity to and recovery from cold face test
Authors: Saperova Elena V. , Dimitriev Dmitry A. 
Published: May 2022

The purpose of this study was to investigate reactivity and recovery to primarily parasympathetic stimulation by cold face test.Sixty five students with a mean age of 20.61±0.13 years take part in the study (86% women, 14% men). They were studied in the morning hours in a quiet room at a comfortable temperature. Time domain (SDNN, RMSSD, pNN50), frequency domain (TP, HF, VLF, LF and LF/HF ratio) and nonlinear (SD1, SD2, ApEn, SampEn, D2, DFA1, DFA2) parameters of HRV were obtained from all participants for 5 minutes before, 5 minutes during and 5 minutes after cold face test (0–1 °C cold compresses) in a supine position. Statistical analysis was performed using Mann‐Whitney test.Heart rate during cold face test was significantly lower than that during rest period (74.03±1.26 vs 76.74±1.21 beat/min, p=0.006). After cold face test cessation heart rate displayed significant decrease compared to cold face test period (71.96±1.17 vs 74.03±1.26 beat/min, p=0.001). Time domain parameters were found to be higher during cold face test than that during rest (SDNN: 52.6±2.85 vs 43.61±2.23 ms, p=0.006; RMSSD: 59.87±4.08 vs 44.99±2.93 ms, p=0.001 and pNN50: 30.49±2.38 vs 22.07±2.13 %, p=0.003). During recovery period time domain parameters remain to be higher, than that during rest: SDNN – 47.97±2.29 ms, RMSSD – 52.16±3.35 ms, pNN50 – 27.24±2.38%.There was no differences during rest period, cold face test and recovery period in TP (2097.89±249.98 vs 2517.24±301.8 vs 2176.12±204 ms2, p=0.744), VLF (83.59±9.99 vs 92.44±12.21 vs 88.33±7.85 ms2, p=0.359), LF (932.86±107.70 vs 1024.98±132.06 ms2, vs 928.54±83.35, p=0.896). High frequency parameter was significantly higher during cold face test than that during rest (1395.36±184.39 vs 1078.11±143.13 ms2, p=0.013). After cold test HF parameter was 1156.11±129.74 ms2(p>0.05).Nonlinear measures were significantly higher during cold face test than that during rest (SD1: 42.39±2.89 vs 31.83±2.07 ms, p=0.001; SD2: 60.52±3.04 vs 52.45±2.50 ms, p=0.025). During recovery period nonlinear parameters remain to be higher, than that during rest: SD1 – 36.92±2.29 ms, SD2 – 56.34±2.44 ms, pNN50 – 27.24±2.38%. ApEn and DFA1 were significantly lower during cold face test than that during rest (respectively, 1.15±0.01 vs 1.40±0.01 and 0.87±0.03 vs 1.01±0.02, p<0.001). During recovery period ApEn was 1.37±0.01 and DFA1 was 0.96±0.03.The other HRV parameters including D2, LF/HF ratio, pLF, pHF, SampEn, DFA2 were not significantly different.These results suggest that cold face test has been associated with increased vagal cardiac control and decrease entropy and DFA1.
The Impact of Short‐Term Tetrahydrobiopterin (BH4) Supplementation on Peripheral Vascular Function in Heart Failure with Preserved Ejection Fraction (HFpEF)
Authors: Bunsawat Kanokwan , Broxterman Ryan M. , Jarrett Catherine L. , Craig Jesse C. , Francisco Michael A. , Alpenglow Jeremy K. , Iacovelli Jarred J. , Ma Christy L. , Ryan John J. , Wray D. W. 
Published: May 2022

BackgroundPatients with heart failure with preserved ejection fraction (HFpEF) exhibit macro‐ and microvascular dysfunction in both the upper and lower limbs that may be mediated by a decline in nitric oxide (NO) bioavailability. Tetrahydrobiopterin (BH4) is a vital cofactor for NO synthase (NOS) activity, the principal enzyme for NO production. BH4 insufficiency contributes to NOS uncoupling, which promotes cellular oxidative stress and limits NO production. While evidence supports the efficacy of BH4 supplementation to reverse NOS uncoupling in other patient populations, the utility of this intervention to restore vascular health has not been examined in HFpEF. We tested the hypothesis that short‐term BH4 supplementation would improve peripheral vascular function in patients with HFpEF.MethodsFive patients with HFpEF (3F/2M; 72±8 years; 31.7±6.1 kg/m2) participated in a randomized, double‐blind crossover study, having consumed either BH4 (Sapropterin, 10 mg/kg) or placebo for 10 days, separated by a 14‐day washout period. Peripheral vascular function was assessed via flow‐mediated dilation (FMD; an index of macrovascular function) and reactive hyperemia (RH, an index of microvascular function) in both the arm (brachial artery, BA) and leg (popliteal artery, PA) at the beginning (pre) and end (post) of each treatment period.ResultsThere were no baseline hemodynamic differences between trials (p>0.05). BA FMD was unchanged following either trial (pre vs. post; BH4: 3.2±2.5% vs. 4.0±1.9%, Δ 0.8±1.4%; Placebo: 2.9±1.9% vs. 2.2±2.2%, Δ ‐0.7±1.1%; p>0.05). Likewise, BA RH was unchanged following either trial (pre vs. post; BH4: 399±206 ml vs. 387±161 ml; Placebo: 242±126 ml vs. 174±149 ml; p>0.05). In contrast, PA FMD improved following the BH4 trial, but was unchanged in the placebo trial (pre vs. post; BH4: 1.5±1.2% vs. 2.5±0.8%; Placebo: 1.6±1.1% vs. 1.3±1.3%; p=0.03). Changes in %FMD for the PA were greater in BH4 compared to placebo (∆ values: 1.0±1.0% vs. ‐0.4±0.4%; p=0.03). No improvements were observed for PA RH (pre vs. post; BH4: 533±257 ml vs. 561±191 ml; Placebo: 682±284 ml vs. 656±107 ml; p>0.05).ConclusionThese findings identify a potential for short‐term BH4 supplementation to improve lower limb macrovascular function in patients with HFpEF. This apparent vascular plasticity suggests that drugs targeting discreet points in the NO pathway may be efficacious in mitigating the disease‐related decline in vascular health in this patient group.
Pharmacological Inhibition of Cullin Neddylation Improves Hepatic Insulin Sensitivity
Authors: Gu Lijie , Chen Cheng , Matye David J. , Hasan Mohammad N. , Clayton Yung‐Dai , Li Tiangang 
Published: May 2022

Background and significanceHepatic insulin resistance is a hallmark feature of non‐alcoholic fatty liver disease (NAFLD) and type‐2 diabetes (T2D) and significantly contributes to systemic insulin resistance. Abnormal activation of nutrient and stress‐sensing kinases leads to serine/threonine phosphorylation of insulin receptor substrate (IRS) and subsequent IRS proteasome degradation, which is a key underlying cause of hepatic insulin resistance. Recently, members of the cullin‐RING E3 ligases (CRLs) have emerged as mediators of IRS protein turnover. CRLs are activated upon cullin neddylation, a process of covalent conjugation of a ubiquitin‐like protein called Nedd8 to a cullin scaffold.AimTo investigate the role of CRLs in regulating hepatic insulin signaling in NAFLD.MethodsNeddylation inhibitor MLN4924 was used to study its effect on insulin sensitivity in liver cells. Hyperinsulinemic‐euglycemic clamp was used to assess MNL4924 effect on insulin sensitivity in vivo. siRNA‐mediated screening was used to identify the Cullin members that mediates IRS protein turnover in liver cells. Co‐immunoprecipitation was performed to study Cullin and IRS interaction. Glucose homeostasis and insulin sensitivity were studied in mice with AAV‐mediated liver specific knockdown of Cul1 or Cul3.ResultsNeddylation inhibition delays CRL‐mediated IRS protein turnover to prolong insulin action in cultured liver cells. Consistently, acute MLN4924 treatment rapidly decreases hepatic glucose production without causing hypoglycemia in mice, while chronic MLN4924 treatment completely normalizes hyperglycemia in obese mice independent of obesity. Hyperinsulinemic‐euglycemic clamp study revealed that MLN4924 significantly increased insulin sensitivity and improved hepatic glucose output. In vitro siRNA based screening showed that knockdown of Cul1 or Cul3, but not other cullin family members, stabilized IRS protein and increased insulin sensitivity in AML12 cells. Consistently, Co‐immunoprecipitation demonstrated IRS interaction with Cul1 and Cul3. AAV‐mediated liver specific knockdown of Cul1 in mice improved insulin sensitivity, lowered fasting glucose, and prevented Western diet‐induced obesity and NAFLD. In contrast, AAV‐mediated liver Cul3 knockdown only decreased fasting glucose in chow‐fed mice but not Western diet‐fed mice.ConclusionThese findings suggest that pharmacological inhibition of cullin neddylation is a novel therapeutic strategy for hepatic insulin sensitization in NAFLD and T2D. This effect may be at least in part mediated by hepatic Cul1 and Cul3 neddylation.
Long‐term myocardial DNA methylation and metabolomic responses to exertional heat stroke in mice
Authors: Murray Kevin O. , Brant Jason O. , Kladde Michael P. , Clanton Thomas L. 
Published: May 2022

Epidemiological studies indicate that exposure to exertional heat stroke (EHS) can increase the risk of all‐cause cardiovascular and systemic disease and promote early mortality. Using a preclinical mouse model of EHS, we previously characterized profound DNA methylation changes in immune cells at 30 d of recovery and severe cardiometabolic disturbances in the ventricular myocardium (VM) at 9‐14 d. These observations indicate that a single exposure to EHS can result in long‐term epigenetic and metabolic alterations. However, whether a long‐term epigenetic responses occur in the VM and or whether cardiometabolic perturbations persist is unknown.PURPOSETo determine if long‐term alterations to (1) DNA methylation and (2) the metabolome occur within the VM after 30 d of recovery from EHS and (3) whether epigenetic alterations predict imbalances within the metabolome.METHODSSixteen C57BL6 female mice underwent a standardized EHS protocol using a forced running wheel (environmental temp: 37.5°C, 40% humidity) or a matched exercise control trial (EXC) (22.5°C). The EHS mice achieved peak core temps of ~42.4°C, accompanied by transient loss of consciousness. Mice were sacrificed after 30 d of recovery; left ventricles were isolated and frozen in liquid nitrogen for DNA methylation sequencing and untargeted metabolomics.RESULTSFollowing 30 d of recovery from EHS, more than 6,000 differentially methylated cytosines (DMCs) were observed within promoter regions; 900 differentially methylated regions (DMRs) were also observed (i.e ≥ 5 differentially DMCs within 300 base pairs) at (Q < 0.05) compared to EXC. Pathway analysis of promoter DMRs indicated changes in genes that modulate basic cell functions, DNA binding, transcription, and metabolism. Cardiometabolic perturbations were found to largely resolve compared to observations at 9‐14 d. Some metabolic disturbances remained, e.g. reductions in α‐ketoglutarate and increases in several lipid intermediates. These remnant alterations are known to be common in early onset heart failure and chronic kidney disease. Repressive DMCs (P < 0.05) were observed within transcriptional regulatory regions of enzymes that regulate α‐ketoglutarate, e.g. isocitrate dehydrogenase 1 & 2 (IDH1 & IDH2), suggesting a potential link with metabolomic findings.CONCLUSIONSA single EHS episode results in a robust epigenetic response in VM when observed at 30 d of recovery, whereas all but a subset of metabolites within the VM had fully recovered. These long‐term molecular changes may induce altered or maladaptive physiological outcomes in response to future environmental or medical challenges.
Obese Animal Serum Derived Vesicles Alter Gene Expression in C2C12 Myotubes
Authors: Pitzer Christopher , Paez Hector G. , Ferrandi Peter J. , Mohamed Junaith S. , Alway Stephen E. 
Published: May 2022

PurposeRegulation of metabolism by extracellular vesicles (EV’s) is an emerging interest due to the ability of vesicle‐bound cargo to alter gene expression. C2C12 myotubes are an in vitro model of murine skeletal muscle fibers. The skeletal muscle is the primary site of glucose disposal in the body. Obesity is known to decrease insulin‐stimulated glucose uptake in the muscle. The purpose of this project was to determine the changes in gene expression caused by serum‐derived extracellular vesicles of an obese animal relative to normal healthy controls. Due to the known association of obesity and dysregulated metabolism, we hypothesized that EV’s isolated from serum of an obese animal would negatively alter metabolically important gene expression.MethodsSerum was collected from obese, but not diabetic (body weight 42 g blood glucose 131 mg/dL) and age‐matched non obese/diabetic control (body weight 26g blood glucose 115 mg/dL), mice and extracellular vesicles were precipitated using a commercially available precipitation reagent (Exoquick, System Biosciences Paolo Alto CA). Fully differentiated myotubes (5 days in differentiation media) were incubated with EV’s (n=4 per group) protein matched to a concentration of 37.5 µg/ml in exosome‐free differentiation media (DMEM supplemented with 1% exosome free FBS and 1% anti‐anti) for 24 hours. Total RNA was isolated using Trizol and cDNA synthesis was performed prior to real‐time PCR experiments.ResultsNR4A1 mRNA expression was significantly increased in obese animal exosome treated myotubes relative to controls (15% increase P=0.016). NR4A2 also tended to increase in obese animal exosome treated myotubes (31% increase P= 0.059) compared to controls. The expression of ND4, a mitochondrially encoded subunit of complex I of the electron transport system, mRNA tended to decrease (11% decrease P=0.091) in the obese animal EV treated myotubes compared to controls.ConclusionsThese data indicate a potential role of obesity‐derived extracellular vesicles in altering metabolic processes of skeletal muscle. The dose of exosomes used in this work was relatively low, therefore more research is warranted to determine if additional effects would be seen at physiological exosome concentrations.
Diurnal Variation in Motivation, Cocaine Value, and In Vivo Dopamine Release
Authors: Iacino Melody C‐L , Stowe Taylor A. , Pitts Elizabeth G. , Ferris Mark J. 
Published: May 2022

Circadian rhythms have been shown to influence a number of psychiatric disorders, like substance use disorder (SUD). For example, individuals with evening chronotypes (i.e. night owls) express higher vulnerability to drug‐craving and drug‐taking behaviors.Similarly, the mesolimbic dopamine (DA) system, which is an essential circuit in these behaviors, exhibits diurnal rhythms in activity and function. Although diurnal rhythms have been documented in both drug‐taking and DA dynamics, it remains unclear whether these variations in DA confer with variations in‐drug taking. Here, we utilized in vivo fast scan cyclic voltammetry and a behavioral economic analysis of cocaine self‐administration to examine time‐of‐day variations in in vivo DA release, motivation, and cocaine value. We hypothesize that the degree to which the magnitude of mesolimbic DA release in the nucleus accumbens (NAc) varies across time will correspond diurnal variations found in motivation to take cocaine. We found that in vivo DA release was increased across the dark cycle in comparison to time‐points in the light cycle. We found no difference in cocaine intake in rats across time‐of‐day when cocaine “cost” was low and easy to obtain (Q0). However, we found that rats in the mid‐point of their dark cycles were more persistent in maintaining high cocaine intake as the “cost” or effort to maintain blood‐levels increased within their session in comparison to rats midway through their light cycle. These novel data suggest that specific time‐points across the dark cycle are associated with corresponding increases in DA and motivation to self‐administer cocaine under high, but no low, cost conditions. Understanding this dynamic modulation of diurnal variations may provide another therapeutic avenue for the circadian intervention of SUDs as well as target time‐points at which current pharmacotherapies might be most effective.
Hyperphosphatemia Contributes to Skeletal Muscle Atrophy in the Absence and Presence of Chronic Kidney Disease
Authors: Heitman Kylie , Czaya Brian , Campos Isaac , Yanucil Christopher , Kentrup Dominik , Westbrook David , Faul Christian 
Published: May 2022

BackgroundChronic Kidney Disease (CKD) is a public health epidemic that is associated with elevated serum levels of phosphate (hyperphosphatemia) as well as skeletal muscle atrophy, but this interconnection is poorly understood. Elevated phosphate (Pi) has direct effects on smooth muscle cells and induces vascular calcification. Pi also induces the production of the hormone fibroblast growth factor (FGF) 23 in bone. We wanted to test if Pi induces atrophy and/or FGF23 expression in skeletal muscle cells. Furthermore, we analyzed skeletal muscle on a functional, histological and molecular level in three models of hyperphosphatemia – two CKD models, i.e. mice with global deletion of collagen 4a3 (Col4a3‐/‐) and wildtype mice receiving an adenine‐rich diet, as well as wildtype mice on a high Pi diet with normal kidney function. Finally, we determined the effect of a low Pi diet on skeletal muscle in Col4a3‐/‐ mice.MethodsC2C12 myotubes were treated with 1‐5 mM Pi for 24 hours, followed by qPCR expression analysis of atrophy genes (atrogenes), including MT1, Trim63, and Fbox32, as well as FGF23. Furthermore, we studied Col4a3‐/‐ mice receiving normal chow or a 0.2% Pi diet at 10 weeks of age. We also analyzed C57Bl/6 mice receiving an adenine‐rich (0.2%) diet for 14 weeks or a 3% Pi diet for 3 months. We analyzed grip strength, hindlimb area by MRI, muscle wet weight, cross‐sectional area of individual muscle fibers immuno‐labeled with anti‐laminin by fluorescence microscopy, and expression levels of atrogenes by qPCR and of FGF23 by qPCR and ELISA.ResultsPi treatments increased the expression levels of atrogenes as well as FGF23 in C2C12 myotubes. In the three mouse models, grip strength and cross‐sectional area of myofibers were significantly reduced, and the expression levels of atrogenes were significantly elevated when compared to respective controls. Furthermore, we detected elevations in the mRNA and protein levels of FGF23 in the hindlimb muscles of all models. Additionally, the two CKD models showed significant reductions in muscle weight and hindlimb area. Administration of a 0.2% Pi diet protected Col4a3‐/‐ mice from developing skeletal muscle atrophy.ConclusionElevated Pi induces myotube atrophy and FGF23 expression in vitro. Mouse models with hyperphosphatemia not only develop skeletal muscle atrophy, but also produce FGF23 in skeletal muscle tissue in the presence and absence of CKD, and a low Pi diet protects the skeletal muscle in CKD mice. Pharmacological approaches targeting Pi uptake or excretion, or inhibition of Pi’s direct actions on tissues might alleviate various CKD‐associated pathologies. Future studies need to determine whether skeletal muscle‐derived FGF23 contributes to tissue injury or is protective against Pi‐induced damage.
Vagus Nerve Sensory Neurons Respond Distinctly to Specific Inflammatory Mediators
Authors: Huerta Tomas S. , Haider Bilal , Adamovich‐Zeitlin Richard , Chavan Sangeeta S. , Tracey Kevin J. , Chang Eric H. 
Published: May 2022

The peripheral nervous system communicates with the immune system in response to injury or infection. In the case of inflammation, sensory signals travel up to the brain via the vagus nerve, which is a major pathway for neuro‐immune communication. While previous work from our group showed that cytokines administered systemically were associated with specific patterns of vagus nerve activity, we did not know how individual vagal sensory neurons encoded this immune information.Here, we use in vivo calcium imaging to monitor the neural activity of individual vagal sensory neurons in response to specific inflammatory mediators. Using mice that express the calcium sensor GCaMP6f in glutamatergic neurons, we imaged neurons of the nodose ganglion in situ using a 1‐photon miniature microscope (Miniscope). During imaging, the inflammatory mediators tumor necrosis factor (TNF) and interleukin 1β (IL‐1β) were applied directly to the vagus nerve. The raw fluorescence data was analyzed with a Python‐based calcium imaging analysis (CaImAn) software and a customized pipelines to output the neural activity (change in fluorescence: ∆F) of individually detected neurons. An average of 69±16.3 neurons were recorded per 1 hour imaging session.Our results reveal that specific vagal sensory neurons respond to differentially to specific immune mediators. The average amplitude, integral, and delay of TNF‐responsive neurons was significantly higher than IL‐1β‐responsive cells (TNF vs IL‐1β, p < 0.01). This result suggests that TNF application triggers responses later and with higher firing rates in responsive neurons compared to IL‐1β. Neuronal responses to IL‐1β had a significantly higher number of peaks when compared to TNF responses (IL‐1β vs TNF, p < 0.05). When compared to responses for the TRPV1‐specific agonist capsaicin, the cytokine responses were found to have significantly lower number of peaks (capsaicin vs IL‐1β, p < 0.05), which suggests that immune mediators produce different neural activity than canonical activators. Taken together, our findings demonstrate that individual vagal sensory neurons encode information about distinct inflammatory stimuli and provide insight into the neural sensing of inflammation. Further investigation into this type of neuro‐immune signaling may identify novel neural targets for the treatment of inflammatory disorders.
Female‐Specific Features of Metabolic Syndrome in an LH Congenic Rat
Authors: Clark Karen C. , Wagner Valerie A. , Holl Katie L. , Reho John J. , Grobe Justin L. , Kwitek Anne E. 
Published: May 2022

Central obesity, high blood pressure, dyslipidemia, and insulin resistance are a collection of cardiovascular and metabolic risk factors that form the basis of the Metabolic Syndrome (MetS) and represent a major public health burden worldwide. The phenotypes that define MetS are all highly heritable, but their genetic complexity necessitates the use of animal models to tease apart novel pathways.The Lyon Hypertensive (LH) rat is a well‐characterized model of MetS, exhibiting spontaneous and profound differences in features of MetS compared to its metabolically healthy control, the Lyon Normotensive (LN) rat. To understand the genomic causes of MetS in the LH rat, we developed a congenic rat model, where a portion of LN chromosome 17 is introgressed on the LH genomic background. Our hypothesis was that differences in metabolic features between the LH controls and the congenic rats (LH17LNa) would be due to the replaced region of the genome. Male and female LH17LNa rats and LH controls were phenotyped for a variety of MetS characteristics, including weekly body growth until tissue collection at 15 weeks of age, body composition by nuclear magnetic resonance (NMR) at 8, 11, and 14 weeks of age, metabolic rate (Promethion system) between 10 and 12 weeks of age, and adipose tissue collection and histological examination.We observed a significant decrease in total body growth in female congenics, beginning at 12 weeks of age and persisting throughout the rest of the study. Prior to the divergence in body weight, female congenics showed significant increases in fat mass and significant decreases in fat free mass that remained consistent at all timepoints measured. We also found significant female‐specific decreases in metabolic rate. Tissue collection revealed the source of the increased adiposity in the female LH17LNa rats was specific to abdominal white adipose tissue, and this phenomenon was further explained by significant hypertrophy in those adipocytes, with no evidence of adipocyte hyperplasia.Genome resequencing of the parental strains identified a nonsense mutation in Ercc6l2, implicating this gene as a strong contender underlying the phenotype differences in the congenics. Ercc6l2 is a helicase involved in transcription‐coupled DNA repair, which is specifically mobilized to repair oxidative stress‐induced DNA damage in post‐mitotic cells. Truncating mutations in Ercc6l2 have previously been implicated in genome instability and premature aging in hematopoetic stem cells in patients with bone marrow failure. The discovery of the significance of Ercc6l2 in the context of female‐specific adipocyte biology could represent a novel role of DNA repair syndromes in MetS pathogenesis.