bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow‐Induced Dilation of Skeletal Muscle Feed Arteries: Relevance to Exercise Hyperemia
Authors: Moore Brittni N. , Jasperse Jeffrey L. 
Published: November 2023

Flow‐induced dilation is the dilatory response seen in arteries as a result of an increase in shear stress along the endothelium. It is often thought that flow‐induced dilation contributes to arterial dilation during exercise as blood flow is increased to working muscle. Previous research compared in vivo shear stress values during rest and exercise to in vitro shear stress values and concluded that flow‐induced dilation of rat soleus feed arteries (Jasperse & Laughlin) is unlikely to contribute to exercise hyperemia. However, the predominantly slow‐twitch soleus is unique in that it contributes to postural maintenance and receives higher amounts of blood flow during stance compared to other hindlimb muscles. Therefore, the aim of the present study was to determine if feed arteries from the predominantly fast‐twitch rat gastrocnemius muscle (GFA) demonstrated flow‐induced dilation and to further assess the potential role of flow‐induced dilation in GFA during exercise. GFA (n=12) from male Sprague‐Dawley rats were isolated and cannulated on two glass micropipettes and intraluminal diameter was measured using videomicroscopy. Pressure was maintained at 90 cmH2O using two independent fluid reservoirs. Changing the height of the fluid reservoirs created a pressure gradient that induced flow through the arteries. Pressure gradients of 2, 4, 6, 8, 10, 15, 20, 30, and 40 cmH2O were used. GFA dilated to increasing flow and shear stress values ranged up to 8.0 ± 0.8 dyn/cm2. The in vitro shear stress response range was compared to calculated in vivo shear stress values from previously published studies. Estimated GFA blood flow values in standing rats are 431 μl/min, in walking rats 816 μl/min, and in running rats 1510 μl/min. Corresponding shear stress values were 95 dyn/cm2 (standing), 180 dyn/cm2 (walking), and 332 dyn/cm2 (running). These in vivo shear stress values far exceed the shear stress values to which GFA dilated in vitro. This comparison suggests that maximal flow‐induced dilation occurs at shear stress values far below those present in GFA in non‐exercising rats and that flow‐induced dilation of GFA is an unlikely contributor to the increase in blow flow seen during exercise.Support or Funding InformationSeaver Research Council of Pepperdine University
Sympatholytic effect of calcitonin gene‐related peptide in rat soleus and gastrocnemius feed arteries
Authors: Brown Megan E. , Humphries M. Harrison , Moore Brittni N. , Jasperse Jeffrey L. 
Published: November 2023

Exercise has been shown to increase sympathetic nerve activity and augment the release of the neurotransmitter norepinephrine at the arterial wall and into the blood. Norepinephrine binds to arterial adrenergic receptors causing vasoconstriction, yet arteries and arterioles constrict less to sympathetic stimulation in contracting skeletal muscle in comparison to resting skeletal muscle. This phenomenon is defined as sympatholysis. Calcitonin gene‐related peptide (CGRP) is a potent vasodilator initially studied in the cerebral circulation but with effects on vascular beds throughout the peripheral circulation. In skeletal muscle, CGRP is released from both sensory and motor neurons. Therefore, we hypothesized that increased levels of CGRP could contribute to sympatholysis. Dose response curves to CGRP (10−12 M to 10−6 M) in soleus feed arteries (SFA) and gastrocnemius feed arteries (GFA) isolated from male Sprague‐Dawley rats were used to compare the vasodilation response to CGRP in muscles of different fiber type. SFA (n = 12) and GFA (n = 8) were isolated and cannulated on two glass micropipettes for in vitro videomicroscopy. Both SFA and GFA dilated significantly to CGRP (SFA: 93.6 ± 2.5% and GFA: 87.8 ± 4.5%) and there was no difference between SFA and GFA in the maximal dilation or sensitivity to CGRP. The constriction response to the α‐1 agonist phenylephrine (PE; 10−9 M to 10−4 M, 0.5 log increments) was measured under control conditions and in the presence of two levels of CGRP (Low: 0.5 nM and Medium: 50 nM) in SFA (n = 6) and GFA (n = 5). Maximal constriction to PE was reduced by CGRP (Control: 82.2 ± 4.4%, Low: 68.4 ± 4.3%, Medium: 70.4 ± 5.1%). Sensitivity to PE (EC50) was also reduced by CGRP. In GFA, neither maximal dilation nor sensitivity to PE was reduced by CGRP. We conclude that CGRP reduces α‐1 mediated constriction in feed arteries from the predominantly slow‐twitch soleus muscle, but not in feed arteries from the predominantly fast‐twitch gastrocnemius muscle.Support or Funding InformationSeaver Research Council of Pepperdine University
Novel Method for Measuring Hepatic Collagen Turnover Rate in Nonalcoholic Fatty Liver Disease (NAFLD): Comparison of Blood and Liver Biopsy Biomarkers of Fibrogenesis
Authors: Hellerstein Marc 
Published: November 2023

Background and ObjectivesExcess collagen synthesis in the liver plays a causal role in progression from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH). Markers that identify a patient's risk for progression, characterize disease activity and provide early assessment of treatment efficacy are needed. In particular, the availability of a non‐invasive metric of the rates of liver collagen synthesis (fibrogenesis) and turnover (fibrolysis) would be extremely valuable. We evaluated novel clinical biomarkers that directly quantify hepatic fibrogenesis rate in well‐characterized patients with biopsy‐proven NAFLD.MethodsPatients with suspected NAFLD and a clinical indication for liver biopsy received the stable, non‐radioactive tracer heavy water (2H2O, 50 ml, 2–3 times daily) by mouth for 20–35 days prior to biopsy. A plasma sample was collected weekly. Collagen fractional synthesis rate (FSR) from liver biopsy tissue and FSR of lumican (a proteoglycan involved in collagen fibril assembly that exhibits increased synthesis when collagen synthesis is increased) from plasma were measured by 2H incorporation, using tandem mass spectrometry (LC‐MS/MS). Magnetic resonance elastography (MRE) measurements of liver stiffness were obtained within 2 weeks of biopsy.ResultsFSR of hepatic type I collagen (Col1a1) was significantly elevated in NASH relative to NAFL (0.97% vs 0.43 %/day, p=0.03). Liver Col1a1 FSR also significantly correlated with fibrosis severity by histological score (r= 0.63), with liver stiffness by MRE (r=0.65), and with HbA1c levels (r=0.47). FSRs of fibrillar hepatic collagen subtypes (I and III) were highly correlated (r= 0.94). FSR of circulating plasma lumican correlated strongly with liver collagen FSR (r=0.69) and with liver stiffness (r=0.71).ConclusionWe conclude that hepatic collagen synthesis rates increase with fibrosis severity in NAFLD patients, indicating not only markedly increased absolute rates of collagen synthesis with disease progression but also suggesting that hepatic scar is dynamic even in advanced disease and may therefore be potentially reversible. Importantly, plasma lumican FSR correlates closely with liver collagen FSR and with liver stiffness. Moreover, established clinical risk factors for disease progression (NASH diagnosis, histologic fibrosis score, diabetes) were associated with higher collagen FSR. Non‐invasive kinetic measurements of fibrogenesis, such as plasma lumican FSR, may be helpful as markers of risk for disease progression and as early read outs of treatment response in anti‐fibrotic trials in NASH. Prospective studies are required to establish the predictive power of fibrogenesis rates for disease progression or reversal.Support or Funding InformationKineMed, Inc.
Experimental Validation of Evolutionarily Conserved Genes Regulating Hypoxia Adaption in Drosophila and Humans
Authors: Zhou Dan , Jha Aashish R , Xue Jin , White Kevin P , Haddad Gabriel G 
Published: November 2023

Hypoxia tolerance is regulated by polygenic mechanisms in metazoan organisms. The following study was performed to determine whether such polygenic mechanisms are shared evolutionarily between organisms like Drosophila and humans. Using a generalized linear mixed model we identified significant allele frequency differences between three independently evolved hypoxia‐tolerant populations and normoxic control populations of Drosophila. Around 50% of the ~3,800 SNP variants are clustered in 66 distinct genomic regions that contain genes that are differentially expressed when hypoxia‐tolerant and normoxic populations were compared. In addition, using genome‐wide SNP data from four high‐altitude human populations (i.e., Sherpas, Tibetans, Ethiopians, and Andeans), we found that several human orthologs of the genes under selection in flies are also likely under positive selection in all four high‐altitude human populations, suggesting that these conserved genes and pathways may regulate hypoxia tolerance in both flies and humans. Currently we have experimentally evaluated the role of these candidate genes in hypoxia tolerance in flies using RNAi‐mediated knockdown. We found that down‐regulation of several candidate genes’ expression, such as pyd, significantly enhanced survival in severe hypoxia in flies. Our results demonstrated that fundamental genetic mechanisms regulating hypoxia tolerance have indeed remained conserved throughout evolution. Such mechanisms may help us to develop novel therapeutic strategies to treat hypoxia‐related diseases in humans.Support or Funding InformationThis work was supported by the following grants from National Institute of Health: Training in Oxygen in Health and Disease Grant T32HL094282 to ARJ; 5P01HD32573 to GGH; and P50 GM081892 to KPW.
Nucleoprotein‐enriched diet prevents disuse‐induced muscle atrophy in soleus muscle of rats
Authors: Nakanishi Ryosuke , Hirayama Yusuke , Ueno Mizuki , Yoshikawa Madoka , Maeshige Noriaki , Fujino Hidemi 
Published: November 2023

Disuse leads to a decrease of mass, fiber cross‐sectional area, protein synthesis, and satellite cell activity in skeletal muscle. It is known that the depletion of amino acids reduces muscle protein synthesis. In addition, nucleotides affect cell proliferation and differentiation. Thus, amino acids and nucleotides are essential nutrition for protein synthesis, cell proliferation, and differentiation in skeletal muscle. Therefore, the present study investigated the effect of nucleoprotein, which has combined amino acids and nucleotides, enriched diet during unloading on protein synthesis, activity of satellite cell, and muscle atrophy. Female Wistar rats were assigned randomly into 4 groups: control group (CON), control with nucleoprotein group (CON+NP), hindlimb unloading (HU), and hindlimb unloading with nucleoprotein group (HU+NP). Fiber cross‐sectional area (FCSA) was significantly higher in HU+NP group than HU group although unloading resulted in a decrease of CSA. In addition, the levels of phosphorylated‐ribosomal protein S6 (rpS6) and extracellular signal‐regulated kinase 1/2 (ERK1/2) were significantly higher in HU+NP group than HU group, whereas the levels of phosphorylated‐p70S6 kinase (p70S6K) were equivalent among these groups. Furthermore, the numbers of MyoD and myogenin‐positive nuclei cells were significantly higher in HU+NP group than HU group. These results suggest that nucleoprotein exerts preventive effects on muscle atrophy via activations of rpS6 and satellite cells, which are regulated with ERK signaling independently from p70S6K pathway.Support or Funding InformationSupported by Grants‐in‐Aid for Science Research from the Japanese Ministry of Education, Culture, Sports, Science and Technology, and the internal funds of Nissan Chemical Industries, Ltd.
Action by Shakuyaku‐kanzo‐to (SKT) and one of its Chemical Components, Glycyrrhetic acid (GA), on Calcium Influx through L‐type Calcium Channel
Authors: Noble Denis , Sam Cynthia , Tasaki Kazuyo Maria 
Published: November 2023

IntroductionOur previous work has shown that SKT, a standardized 1:1 combination of root extracts from paeony and licorice, rapidly relaxes smooth muscle within 1–2 mins, and slowly relaxes skeletal muscle within about 30 minutes (Sam, Terrar, Tasaki & Noble, 2015a). We have also shown that increasing extracellular potassium from 5.4 to 10.8 mM is a powerful facilitator of the relaxing action of SKT in skeletal muscle (Sam, Terrar, Noble, Tasaki & Noble, 2015b).MethodsTo investigate possible molecular mechanisms we recorded calcium influx through the alpha1 pore‐forming subunit of the L‐Type calcium channel expressed in HEK293 cells. Influx was estimated by measuring the difference in Fura‐2 fluorescence before and after activating the channels with high (100 mM) potassium. Patch clamp recordings were done at −80 mV and depolarising pulses were applied from −80 to +40 mV. Pulse duration was between 50 and 200 ms. In some experiments ramps were applied from −100 to +100 mV.ResultsSKT produced up to 50% inhibition of calcium influx through the pore‐forming subunit of the L‐type calcium channel in HEK cells (Figure 1). The results also show considerable variability that may be consistent with differing actions of some of the individual chemical components.One of the pure chemical components, GA, however produces a consistent and statistically significant inhibition of calcium influx, which is up to 80% (Figure 2).DiscussionIn muscle cells, such inhibitions of calcium influx would be expected to deplete cell calcium and so reduce the phasic contractile response and relax tonic resting tension. Since ICaL plays an immediate role in smooth muscle but only a long term role in skeletal muscle, this would be consistent with our previous observation of different time courses between SKT's actions on smooth and skeletal muscles.There was, however, no statistically significant inhibition of calcium current using controlled voltage patch clamp recording. The action on inhibiting influx could therefore be indirect.Support or Funding InformationAcknowledgement: This research is conducted by the University of Oxford Innovative Systems Biology Project Sponsored by Tsumura. We thank TSUMURA & CO for their support.
Hypothalamic APPL2 Acts as A Key Mediator in Maintaining Energy Homeostasis by Controlling Thermogenesis in Subcutaneous White Adipose Tissue
Authors: Wang Baile , Cheng Kenneth King Yip , Li Xiaomu , Wu Kelvin Ka Lok , Jin Leigang , Jiang Xue , Liu Zhuohao , Zhou Yawen , Xu Aimin 
Published: November 2023

ObjectiveTo investigate the role of hypothalamic APPL2, a close homolog of APPL1 (which has been reported to have regulatory effects on glucose metabolism), in regulation of energy metabolism.IntroductionInduction of browning in white adipose tissue (WAT), defined by transformation from white adipocytes to brown adipocytes, not only promotes adaptive thermogenesis but acts as a defensive mechanism to protect against obesity and its related metabolic disorders. Browning is tightly controlled by the cross‐talk between the energy controlling center hypothalamus and WAT, yet the underlying mechanism is unclear. In this study, we investigated whether the adaptor protein APPL2, a key player in adiponectin and insulin signaling, controls browning by mediating the cross‐talk between hypothalamus and WAT.MethodAPPL2flox/flox mice were crossed with rat insulin promoter Cre transgenic mice to generate hypothalamus and pancreatic β cell specific APPL2 knockout (RIP‐APPL2‐KO) mice, or locally injected with adenovirus‐associated virus (AAV) encoding Cre into ventromedial hypothalamus to generate APPL2 hypothalamus specific knockout mice. Basic metabolic parameters were monitored for 24 weeks. Cold challenge was employed to induce browning in the above mice.ResultsRIP‐APPL2‐KO mice displayed increased adiposity accompanied by a dramatic reduction of oxygen consumption. Such impairments were exacerbated when these mice were fed with a high‐fat diet. Upon 6‐hour cold exposure, RIP‐APPL2‐KO mice were cold sensitive due to the defective lipolytic and thermogenic responses in WAT but not BAT. During chronic cold acclimation, browning program was almost absent in subcutaneous WAT (sWAT) of RIP‐APPL2‐KO mice, whereas no obvious change appeared in their BAT. The impaired browning in RIP‐APPL2‐KO mice was due to decreased neuronal activation in raphe pallidus and subsequent diminished sympathetic outflow to sWAT. Peripheral treatment of CL316243 (β3 adrenergic receptor agonist), which bypassed SNS activation, could reverse the impaired browning phenotype in sWAT of RIP‐APPL2‐KO mice, indicating that the defect does not lie in sWAT but in hypothalamus. Likewise, adeno‐associated virus (AAV)‐mediated specific knockout of APPL2 in ventromedial hypothalamus recapitulated the defective browning phenotypes of RIP‐APPL2‐KO mice.ConclusionOur study uncovers a novel role of ventromedial hypothalamic RIP neurons in maintaining energy homeostasis by controlling browning in sWAT with the involvement of the adaptor protein APPL2.Support or Funding InformationThis work was supported by Health and Medical Research Fund (HMRF 01231606 to KKY Cheng).
Cardiac Autonomic Function is Impaired in Adolescents with Mild Traumatic Brain Injury
Authors: Abbott Kolten C. , Badrov Mark B. , Elfassy Jonah , Moir M. Erin , Fischer Sara A. , Fischer Lisa K. , Fraser Douglas D. , Shoemaker J. Kevin 
Published: November 2023

Mild traumatic brain injury (mTBI), of which concussion is a subset, are a major pediatric public health concern. Children and adolescent populations not only report the highest incidence of concussions, but are also more likely to experience symptoms which persist beyond the 2‐week period of spontaneous healing. In order to reduce the transition of acute symptoms into long‐term negative consequences, objective diagnostic and management tools are essential. However despite increased awareness, clinicians remain reliant on subjective symptom analyses and neuropsychological evaluations to diagnose and manage concussive injuries. Furthering our understanding of the pathophysiological response of an adolescent brain following a concussive injury may provide the foundation for the development of objective biomarkers. Therefore, the purpose of this investigation was to evaluate cardiac autonomic function in adolescents acutely diagnosed with a concussion. More specifically, autonomic function was evaluated while in the supine position, via heart rate variability (HRV; time‐and frequency‐domain) and cardiovagal baroreflex sensitivity (BRS; sequence method) in 16 adolescents diagnosed with a concussion (mTBI; 11 females; 16 ± 2 yrs, 173 ± 9 cm, 69 ± 15 kg) and 16 age‐matched controls with no previous history of concussion (CTRL; 7 females; 14 ± 2 yrs, 168 ± 8 cm, 66 ± 15 kg). mTBI patients were 9 ± 4 days post‐injury and presented with a SCAT3 symptom score of 14 ± 7. Compared to CTRL, mTBI patients had significantly lower standard deviation of normal RR intervals (SDNN; 56 ± 20 vs. 88 ± 40 ms; P < 0.01, Cohen's d = 1.06) and root mean square of successive differences (RMSSD; 59 ± 27 vs. 98 ± 57 ms; P < 0.05, d = 0.94). Furthermore, in the frequency domain, both total power (3491 ± 2482 vs. 8954 ± 7932 ms2; P < 0.05, d = 1.05) and high frequency power (1555 ± 1223 vs. 3644 ± 3334 ms2; P < 0.05, d = 0.92) were reduced in mTBI patients compared to CTRL, while a trend for reduced low frequency power in mTBI patients was observed (989 ± 726 vs. 2986 ± 4028 ms2; P = 0.07, d = 0.84). Finally, compared to CTRL, cardiovagal BRS was lower in mTBI patients (32 ± 14 vs. 52 ± 36 ms/mmHg; P < 0.05; d = 0.81). The results of this study suggest that adolescent concussions are characterized by cardiac autonomic dysregulation. The utility of HRV and BRS to assist clinicians in the early diagnosis of adolescent concussion warrants further investigation.Support or Funding InformationThis work was supported by the Children's Health Research Institute (London, Canada).
Central Angiotensin‐II Increases Renal Sympathetic Nerve Activity Via Rho Kinase Activation in Conscious Rabbits
Authors: Pellegrino Peter Ricci , Schiller Alicia Marie , Haack Karla K. , Zucker Irving H. 
Published: November 2023

BackgroundA growing body of evidence implicates elevated renal sympathetic tone and activation of the renin‐angiotensin system in the pathogenesis and progression of cardiovascular disease. The RhoA/Rho kinase pathway is an important mediator of the effects of Angiotensin‐II (AngII) in the periphery, but the functional role of this pathway in AngII‐induced renal sympatho‐excitation is not well‐characterized.HypothesisWe hypothesized that central inhibition of the RhoA/Rho kinase pathway prevents AngII‐mediated renal sympatho‐excitation.MethodsSixteen male New Zealand White rabbits were chronically instrumented with renal sympathetic nerve electrodes, arterial pressure telemetries, and lateral ventricle cannulae. Each rabbit received an intracerebroventricular infusion of AngII, the Rho kinase inhibitor Fasudil (Fas), AngII and Fas, or a vehicle infusion. Seven days after renal nerve electrode implantation, baseline renal sympathetic nerve activity was recorded and quantified by normalization to the nasopharyngeal reflex. Following the study, Rho kinase activity was assessed by performing quantitative immunofluorescence for a phosphorylated form of the Rho kinase target MYPT on midsagittal brain slices using a LiCor Odyssey scanner.ResultsCentral AngII infusion significantly raised baseline renal sympathetic nerve activity, but coadministration of the Fas blocked this renal sympatho‐excitation. Importantly, Fas alone had no effect on baseline renal sympathetic nerve activity, resulting in a statistically significant interaction between AngII and Fas. Central AngII infusion increased phospho‐MYPT fluorescence, both diffusely and in the subfornical organ, an important autonomic center, while Fasudil coadministration blocked this Rho kinase activation.ConclusionActivation of the RhoA/Rho kinase pathway is necessary for central AngII‐mediated renal sympatho‐excitation.Support or Funding InformationSupported by NIH F30 HL118974 and NIH P01 HL062222.
Assesing the role of B7‐1 in Diabetic Nephropathy
Authors: Herrera Marcela , Soderberg Magnus , Molne Joan , Santamaria Beatriz , Balverde Angela , Heasman Stephanie , Jermutus Lutz , Baker David , Moreno Carol 
Published: November 2023

Diabetic Nephropathy (DN) remains an unmet medical challenge as its prevalence is projected to continue to increase and specific medicines for treatment remain undeveloped. Activation of the immune system, in particular T‐cells, is emerging as a possible mechanism underlying DN disease progression in humans and animal models. We hypothesized that inhibition of T‐cell activation will ameliorate DN. Interaction of B7‐1 (CD80) on the surface of antigen presenting cells with its binding partners, CTLA4 (CD152) and CD28 on T‐cells, is essential for T‐cell activation. In this study we used a soluble CTLA4‐Fc fusion protein to block cell surface B7‐1, preventing the cellular interaction and inhibiting T‐cell activation.The CTLA4‐Fc Abatacept was dosed i.p. in the Streptozotocin‐induced Diabetic Nephropathy mouse model in both prevention and intervention modes. Renal damage was assessed by albuminuria and renal B7.1 positive cells and lymphocytes were measured by immunohistochemistry. Gene expression interrogated by real‐time PCR and protein expression by Western blotting. Differentiated human immortalized podocytes were used for in vitro studies.When CTLA4‐Fc was dosed in an animal model of DN, it reduced albuminuria in both prevention and intervention modes. The number of T‐cells infiltrating the kidneys of DN animals correlated with the degree of albuminuria and treatment with CTLA4‐Fc reduced the number of renal T‐cells. As B7‐1 induction has been recently proposed to underlie podocyte damage in DN, CLTA4‐Fc could be efficacious in DN by protecting podocytes. However, this does not appear to be the case as B7‐1 was not expressed in: 1) kidneys of DN animals; 2) stimulated human podocytes in culture; or 3) glomeruli of DN patients.We conclude that CTLA4‐Fc ameliorates DN by blocking T‐cell activation and not by protecting podocytes.