bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Electrodes to Record Neural Signals in the Periphery
Authors: Verma Nishant , Knudsen Bruce , Skubal Aaron , Gholston Aaron , Frank Jennifer , Ludwig Kip 
Published: May 2022

Appropriately designed electrodes to make in vivo recordings of neural activity have been essential to understanding the nervous system. Recording electrode design has been extensively explored for use in measurement of naturally occurring neural activity in the brain. Recently, recordings of evoked compound action potentials (ECAPs) in the periphery have garnered interest due to their relevance in neuromodulation therapies for determining target engagement and enabling closed‐loop operation. Here, we compare three types of recording electrodes – microelectrodes, cuff electrodes, and intrafascicular electrodes – and their ability to make in vivo recordings of electrically ECAPs, naturally occurring neural activity, and sensory evoked neural activity in the peripheral nerves of a human‐relevant large animal model.The great auricular nerve, innervating the auricle, and cervical vagus nerve of domestic pigs were instrumented with the three recording electrodes. Naturally occurring neural activity, sensory evoked neural activity induced by gentle brushing of the auricle, and electrically ECAPs initiated by non‐invasive and invasive stimulation electrodes were recorded. The study was pre‐registered (https://osf.io/y9k6j).We showed that the recording cuff had superior performance in measuring invasive electrically ECAPs (p < 0.05) while the tungsten microelectrode, routinely used for microneurography in humans, had superior performance in measuring naturally occurring action potentials (p < 0.05). The microelectrode was still able to record electrically ECAPs. Further, we show how choice of reference electrode position may be optimized per application.Microneurography recordings paired with the deployment of a non‐invasive neuromodulation therapy can be used to functionally map sensory innervation areas in patients, allowing individualized placement of stimulation electrodes to achieve on‐target neural fiber activation. These findings provide a basis to select recording electrode type and configuration for measurement of neural signals in the development and deployment of neuromodulation therapies.
The Effects of Ribosomal Proteins uS2, uS3, and uS4 on Transcription
Authors: Blaha Gregor M. , Diggs Stephen , Tam Timothy K. , Hakopian Sheron , Rodriguez Carlos 
Published: May 2022

In E. coli, transcription and translation are coupled and ribosomes can directly contact RNA polymerase. The contacts are formed between the RNA exit site of the RNA polymerase and ribosomal proteins uS2, uS3, or uS4 on the ribosome. We assessed the effects of ribosomal proteins uS2, uS3, and uS4 on transcription. In varying degrees, they all reduced termination and increased pausing. Although uS2 bound directly to the polymerase, it affected transcription the least. uS3, which did not bind the polymerase, had the most prominent effects on transcription.We suggest uS2 acts as an anchor for the polymerase during coupling of transcription and translation. Likewise, uS3 and uS4 may affect transcription depending on the length of RNA between the ribosome and polymerase. We speculate that ribosomal proteins may also coordinate the transcription of ribosomal RNAs with their assembly into ribosomes. Finally, we submit that the intrinsic effects of ribosomal proteins may drive the tight regulation of their expression in the cell.
Gender Differences in Perceived Stress and Biological Stress Markers are Associated with Changes in Resting Heart Rate
Authors: Chirico Erica N. , Khamisani Azmeer 
Published: May 2022

ObjectiveOur study objective is to evaluate whether gender differences in both perceived and biological stress levels will alter resting heart rates.HypothesisWe hypothesize that females will experience higher levels of perceived and biological stress which will translate to a higher resting heart rate compared to males.Methods19 first‐year medical students participated in this study. Participants wore Fitbits to collect heart rate data throughout the course of the academic year. During exam weeks (the “stressor”), participants filled out a standard psychometric questionnaire to assess perceived stress levels and saliva samples were collected to measure cortisol and alpha‐amylase concentrations.ResultsOur study showed that females have higher resting heart rates than males (65.8±6.8 bpm vs 57.7±4.34 bpm, p<0.001). Females recorded having higher perceived stress levels than males (7.9±4.6 vs. 2.12±5.27, p<0.001), as well as having higher salivary alpha‐amylase concentrations than males (33.95±29.50 U/mL vs. 75.4±76.44 U/mL p=0.001). No difference in salivary cortisol concentrations between females and males are seen (0.44±0.25 ug/dL vs. 0.39±0.24 ug/dL, p= 0.3).In females, there is a weak positive correlation between RHR and perceived stress level (0.22), as well as with amylase (0.26). In males, there is a moderate negative correlation between RHR and perceived stress level (‐0.48) and a weak positive correlation between RHR and cortisol (0.26). There was no relationship between RHR and amylase.ConclusionFemales have higher levels of perceived stress levels which is in agreement with their higher levels of alpha‐amylase, a marker of psychosocial stress via the sympatho‐adrenal‐medullary system. As salivary alpha‐amylase has been suggested to reflect catecholaminergic reactivity, it seems likely that this is responsible for the increased resting heart rate. This relationship is not consistent in males where perceived stress is associated with a decrease in RHR. However, in males a relationship was seen between biological markers of stress (cortisol via the hypothalamic‐pituitary‐adrenal axis) and RHR. This study suggests that the relationship between biological measures of stress and heart rate vary with gender and that females experience an increased level of perceived stress overall.
Pigment epithelium‐derived factor induced CRX alterations in the mouse retina
Authors: Rebustini Ivan T. , Crawford Susan E. , Becerra S. P. 
Published: May 2022

The gene Serpinf1 encodes for Pigment Epithelium‐Derived Factor (PEDF), which protects photoreceptors from cell death. The Serpinf1 null mouse exhibits normal retinal function; however, PEDF deficiency increases retinal degeneration susceptibility in rd10 mouse. CRX is a transcription factor that regulates expression of several photoreceptor specific genes, including opsins and phosphodiesterase. This study aims to explore whether regulation of CRX activation is one mechanism by which PEDF exerts photoreceptor survival.Serpinf1‐/‐, Serpinf1+/‐ and Serpinf1+/+ mice at 3 months of age were used. We prepared cultures of mouse retinal explants. They were treated with recombinant human PEDF. Zaprinast (a PDE inhibitor) was added to induce photoreceptor death. We determined cell death using PSVue‐550, a visible fluorescent probe for detection of phosphatidylserine on the surface of cells. Subcellular distribution of CRX, PDE6A and pan‐acetylation was detected by immunofluorescence. The transcriptional levels of Crx, Pde6a, Opn1mw and Opn1sw were assessed using qPCR.PEDF treatment induced the expression of Crx and its regulated genes Pde6a, Opn1mw and Opn1sw. PEDF also enhanced the CRX immunoreactivity in the nuclei of photoreceptors. In contrast, the nuclear CRX immunoreactivity was suppressed in photoreceptors from retinas of Serpinf1‐/‐ mice deficient of PEDF. PDE6A immunoreactivity also decreased in Serpinf1‐/‐ photoreceptors compared to those from Serpinf1+/+ mice. Histone acetylation was detected in discrete photoreceptors in Serpinf1+/+ but was undetectable in the Serpinf1‐/‐ retinas. Zaprinast‐induced photoreceptor death was more pronounced in Serpinf1‐/‐ retinal explants than in wild type controls. PEDF pre‐treatment prior to the zaprinast treatment improved photoreceptor survival and enhanced CRX immunoreactivity in both Serpinf1‐/‐ and Serpinf1+/+ retinal explants. Deletion in PEDF in the Serpinf1 null mice accelerated retinal degeneration induced by zaprinast, which was prevented by exogenous addition of PEDF in retinal explants.The findings imply that PEDF activated the CRX‐associated transcription factor network. They provide a novel insight linking extracellular PEDF to nuclear CRX during photoreceptor survival.
Cellular redox regulation by the neuronal glutamate and cysteine transporter, EAAT3
Authors: Radhakrishnan Saranya , Amara Susan G. 
Published: May 2022

Glutamate transporters are essential for clearing glutamate from the extracellular space and thus limit the actions of glutamate within the brain. The neuronal glutamate transporter EAAT3 has also been shown to transport cysteine, which serves as a rate‐limiting substrate for the synthesis of neuronal glutathione, an essential regulator of oxidative stress in cells. Hence, EAAT3 can contribute to regulating cellular redox by acting as an essential cysteine transporter in neurons. EAAT3 mutations are also associated with several neuropsychiatric disorders such as schizophrenia and obsessive‐compulsive disorders.The activity of plasma membrane transporters can be altered by changes in trafficking, expression levels and recycling of the transporters. EAAT3 can rapidly cycle to and from the cell surface and through intracellular compartments within a few minutes and this can be regulated through several different intracellular signaling pathways. Previous studies have demonstrated that activation of protein kinase C (PKC) can regulate EAAT3 trafficking and increase the localization of EAAT3 at the membrane surface. There is evidence for some redox‐triggered mechanisms that can directly or indirectly influence signaling by altering the catalytic properties or influencing subcellular compartmentation of different PKC isoforms. This suggests a mechanism by which EAAT3 trafficking could be modulated by PKC as a response to cellular redox stress to increase cysteine import and facilitate the synthesis of the antioxidant glutathione. To study this, we monitored if oxidizing agents such as hydrogen peroxide can stimulate a redox response in the cell and lead to increased membrane localization of EAAT3. We found that application of hydrogen peroxide leads to an increase in EAAT3 membrane localization in Neuro2A cells expressing EAAT3. We used TIRF and biotinylation assays to confirm that EAAT3 localization can be altered by PKC activation and further examined whether this surface expression can be additionally modulated during redox stress.While studying downstream redox changes upon cysteine and antioxidant N‐acetyl cysteine treatments, we noticed a transient oxidative response in the mitochondria resulting from the generation of sulfane sulfur species and hydrogen sulfide in the mitochondria. To understand these downstream effects of cysteine and N‐acetyl cysteine on cytosolic and mitochondrial stress, we monitored the redox changes in the cytosol and mitochondria with live‐cell imaging using genetically encoded fluorescent redox sensors targeted to specific subcellular compartments. Using this approach, we were able to conduct live‐cell imaging with spatiotemporal accuracy and to dissect sub‐cellular changes in different redox couples caused by cysteine treatments. We also investigated cysteine transport and N‐acetyl cysteine transport through EAAT3, both of which appear crucial to cellular redox regulation in neuronal cells that have high mitochondrial activity and metabolic burden.
Kinetics of Plant‐derived Heteropolysaccharide Bioabsorption Characterized by Fluorescence‐based Microfluidics System
Authors: Liao Matthew W. , Liu Betty S. , Wagner Willi L. , Khalil Hassan A. , Chen Zi , Ackermann Maximilian , Mentzer Steven J. 
Published: May 2022

Plant‐derived structural polymer, pectin, is the “glue” between plant cells, a biomaterial with promising performance as a sealant on visceral organs. However, the nature of bioabsorption and biodurability of pectin remains unclear. Here, we investigate the feasibility of a quantitative microfluidic perfusion assay based on photochemical quenching, to define the kinetics of pectin bioabsorption.We hypothesize that fluorescent tracers embedded into pectin biopolymers will reliably reflect predictable kinetics patterns of bioabsorption including predictable trends when modifying the chemical species used in fluorescence quenching experiments.A fluorescent tracer, Fluorescein Sodium, was embedded into high methoxyl citrus pectin. Dried Fluorescein pectin films were placed into 24‐well plates, to monitor degradation via parallel microfluidics perfusion. This perfusion was performed via micro‐perfused exogenous 0.4% Trypan Blue, an anionic hydrophilic azo dye, which was delivered into porous matrix interfacing on pectin in each well. To assess biodurability, the fluorescence of perfused pectin under quenching by dye was monitored over time using a multi‐well plate fluorescence reader (Cytofluor 4000, PerSeptive Biosystems).Our data show that consistent trends in fluorescence result during quenching experiments. When un‐perfused, Fluorescein‐embedded pectin exhibited statistically insignificant change in quantum yield over 1 week (p=0.457), suggesting that results were not impacted by substantial photobleaching over the course of experimentation. To minimize interfacial flow artifact, 6µm porous matrix provided an effective interface for observable perfusion of azo dye into pectin. During micro‐perfusion, serial measurements of fluorescence in Fluorescein pectin demonstrated exponential decline in fluorescence intensity. This quenching of fluorescent signal from Fluorescein correlated with the progressive bioabsorption of the pectin polymer. Absorption was feasibly modulated by adjusting dye volumes used in perfusion.In this in vitro assay, plant‐derived pectin exhibits predictable decay characteristics and bioabsorption kinetics when incorporated with fluorescent tracers. These tracers not only provide a quantitative measure of biodurability, but also an opportunity for guided biochemical tuning of the complex biomaterial, to improve its performance as a potential therapeutic sealant.
Compound 48/80 increases bladder wall compliance independent of mast cells
Authors: Saxena Pragya , Roccabianca Sara , Tykocki Nathan 
Published: May 2022

Changes in wall compliance are seen in many bladder pathologies, such as fibrosis and diabetes. Some of these pathologies can be caused by basic secretagogues like Compound 48/80 and its endogenous analogue, Substance P. Traditionally it is believed that basic secretagogues rapidly degranulate mast cells and release inflammatory mediators by acting on an orphan receptor, Mas‐related G protein‐coupled receptor B2 (Mrgprb2). While Compound 48/80 does increase wall compliance, the exact location and function of Mrgprb2 in the urinary bladder are still unknown. We hypothesize that changes in bladder wall compliance caused by Compound 48/80 are mediated through Mrgprb2 receptors but independent of mast cell degranulation.Whole mouse bladders from C57Bl/6 (wild‐type) and C‐kitW‐sh (mast cell‐deficient) mice were dissected and mounted in a custom designed pentaplanar reflected image macroscopy (PRIM) system for simultaneous measurement of transient pressure events, intravesical pressure, bladder volume, wall stress, and wall stretch during ex vivo bladder filling. Wall compliance was derived as a measure of the stress versus stretch relationship using the pressure‐volume curves and associated imaging data. To test our hypothesis, bladders were exposed to either vehicle or Compound 48/80 (10 µg/ml) during ex vivo filling. Compound 48/80 significantly increased the leading slope of transient pressure events in both wild‐type and mast cell‐deficient mice. Compliance was also increased, as shown by decreased stress per change in stretch. We also collected urothelium and detrusor layers from C57Bl/6 and C‐kitW‐sh mouse bladders. Layers were separated using blunt dissection, and RNA was isolated for measurement of Mrgprb2 expression using qRT‐PCR. No significant difference in the expression of Mrgprb2 mRNA was observed between the two mouse models in either the urothelium or detrusor layers. These findings suggest that Mrgprb2 receptors are also expressed outside of mast cells in the urinary bladder wall and, when activated by Compound 48/80, increase wall compliance and the leading slope of transient pressure events.
Genetic and molecular basis of Adaptive and Mal‐adaptive excessive erythropoietic responses in the Andean region
Authors: Azad Priti , Zhou Dan , Haddad Gabriel 
Published: May 2022

RationaleExcessive Erythrocytosis (EE) is a predominant trait in some high‐altitude dwellers (Chronic Mountain Sickness, CMS, or Monge’s disease) but not others living at the same altitude in the Andes, we took advantage of this human “experiment in nature” and studied both populations (with CMS and without, non‐CMS). This population provides a unique opportunity to study both adaptive (non‐CMS) and mal‐adaptive (CMS) mechanism(s) and understand the molecular basis of regulating erythropoiesis at high altitude.MethodsIn order to understand the molecular basis for polycythemia of high altitude, we generated a disease in‐the dish‐model by re‐programming fibroblasts from CMS and non‐CMS subjects. In the past, we have discovered that there are selective sweeps that seem to be statistically different between CMS and non‐CMS and hence contain candidate genes. In this study, by manipulating expression of these candidate genes (Eg. SENP1, ARID1B) in our in‐vitro model system, we delineate the molecular mechanism(s) of the CMS polycythemia as well adaptive response to suppress the excessive response in non‐CMS subjects.ResultsAs compared to sea level controls who responded to hypoxia by increasing their RBCs modestly, CMS cells increased theirs remarkably (up to 60 fold) with a dose‐dependent response to graded hypoxia (1.5, 5, 10% O2). Non‐CMS cells showed a blunted increase in RBC production under hypoxia. In order to understand the genetic basis of these phenotypes, we knocked down SENP1 (a desumoylase) in CMS iPS cells using lentiviral constructs and observed a striking reduction (>90%) of the CMS excessive erythropoietic response to low O2. Similarly, by knocking down ARID1B (subunit of a SWI/SNF chromatin remodeling complex) in non‐CMS we observed that RBC formation increased significantly under hypoxia. Our recent results suggest a critical role of ARID1B at the chromatin level in regulating erythroid transcriptional factors such as GATA1.Conclusion. Our results demonstrate the presence of a regulatory system (SENP1 and ARID1B) that is critical in erythropoiesis and that is out of balance in the CMS subjects and tightly regulated in adapted non‐CMS subjects. Our results indicate that SENP1 and ARID1B both regulate GATA1 levels albeit through unique mechanism(s) in CMS patients as well as adapted non‐CMS subjects. Therefore, studying both populations is essential in understanding the erythropoietic response under hypoxia at high altitude.
Localization and Functional Characterization of the Cannabinoid Receptor Type 1 (CB1R) in the Kidney
Authors: Rein Joshua L. , Mackie Ken , Kleyman Thomas R. , Satlin Lisa M. 
Published: May 2022

IntroductionCannabis and synthetic cannabinoid consumption is increasing worldwide. The impact of their consumption on human health including the risk of kidney disease and its associated complications is uncertain. The kidney, among other organs, produces endogenous cannabinoids (endocannabinoids, ECs) that act on the G‐protein‐coupled cannabinoid receptors type 1 (CB1R) and type 2 (CB2R). ECs and CB1R agonists acutely act as diuretics with variable effects on Na+, K+, and HCO3– excretion. As the aldosterone sensitive distal nephron (ASDN) is responsible for the final renal regulation of total body electrolyte, acid/base, and water balance that is mediated by principal cells (PCs) and intercalated cells (ICs), we sought to examine the cell specific expression of components of the EC system in the mouse collecting duct and the acute changes in urine composition after administration of the cannabinoid receptor agonist WIN55,212‐2 (WIN).MethodsCB1R and AQP2 localization were examined by immunofluorescence microscopy in cryosections of kidneys harvested from non‐manipulated male C57BL/6 mice (7‐12 weeks of age) using protein‐specific Abs. A subset of whole animal metabolic studies were performed in mice that were acid‐loaded by provision of 20 mM NH4Cl and 1% sucrose added to the drinking water x 7d. On the day of experimentation, mice were allowed to spontaneously void, then injected SC with either 1.5 mg/kg WIN or vehicle control (10% Tween‐80 and 10% DMSO in 1x PBS) in a volume <1% BW. Urine was collected for up to 4hr for measurement of volume, pH, osmolality, Na+ and K+.ResultsIn the ASDN, CB1R was localized to AQP2(‐) cells, and thus presumably ICs. Acid‐loaded mice treated with WIN (n=5) had similar UpH, UNaV, and UKV to untreated mice (n= 4) but had a higher urine output (UOP) (24.1 ± 6.5 vs. 13.6 ±1.2 µL/gBW/4hr; (P=0.02) and a lower UOsm (822 ± 335 vs. 1912 ± 293 mmol/kg H2O; P=0.001). WIN‐treated non‐acid loaded mice (n=7) urinated more frequently (3.6 ± 2.2 vs. 0.4 ± 0.5 micturitions/2 hr; P=0.05), had a lower UOsm (315 ± 82 vs. 1449 ± 553 mmol/kg H2O; P<0.0001), and lower UKV (0.4 ± 0.2 vs. 0.9 ± 0.3 µmol/gBW/2hrs; P=0.002) compared to controls (n=8), whereas UNaV and UpH were similar. Furthermore, WIN reduced the apical/cytoplasmic ratio of AQP2 expression in PCs of the inner medulla by 43% (n=209 cells in 4 mice) compared to controls (n=183 cells in 4 mice) (P<0.0001).ConclusionICs express CB1R. Although UpH and Na+ excretion were unaffected in either acid‐loaded or non‐acid loaded mice by WIN, the cannabinoid receptor agonist induced diabetes insipidus, a disorder characterized by the excretion of large volumes of dilute urine, and reduced K+ excretion in non‐acid loaded mice. Efforts are underway to determine whether this effect is central or nephrogenic. These results promise to reveal how cannabis affects kidney function and to identify potential targets for novel therapeutics to treat water and electrolyte disorders.
Exercise Responsiveness in Obese Adults
Authors: Gries Kevin , Hart Corey , Kunz Hawley , Ryan Zachary , Zhang Xiaoyan , Parvizi Mojtaba , Liu Yuanhang , Dasari Surendra , Lanza Ian 
Published: May 2022

Obesity is associated with several skeletal muscle impairments which can be improved through an aerobic exercise prescription. The possibility that exercise responsiveness is diminished in people with obesity has been suggested but not well‐studied.PURPOSEThe purpose of this study was to investigate how obesity influences acute exercise responsiveness within skeletal muscle.METHODSNon‐obese (NO; n=19; 10F/9M; BMI=25.1 ± 2.8 kg/m2) and Obese (O; n=21; 14F/7M; BMI=37.3 ± 4.6 kg/m2) adults performed 30 minutes of single‐leg cycling at 70% of VO2peak. Serial muscle biopsies (vastus lateralis) were collected before exercise and 3 and 6 hours post‐exercise to measure protein synthesis and gene expression.RESULTSThe exercise‐induced fold change in mixed muscle protein synthesis trended (p=0.058) higher in NO (1.28 ± 0.54‐fold) compared to O (0.95 ± 0.42‐fold) and was inversely related to BMI (r=‐.374, p=0.027). RNA sequencing revealed 331 and 280 genes that were up or downregulated after exercise in NO and O, respectively. Gene set enrichment analysis showed O had blunted post‐exercise pathways related to MAPK signaling, chemokine‐mediated signaling, FC receptor mediated stimulation signaling, cell proliferation, apoptosis, and RNA polymerase II promotion. Quantitative polymerase chain reaction of select metabolic (PGC1a, PGC1b, TFAM, PDK4, IRS, MAPK, and PRKAA1) and muscle growth (SLC, TBC, MSTN, MyoD, TRIM32, FOX03, and FBXO3) genes were similar between groups 3 and 6 hours after exercise.ConclusionThese data highlight several unique pathways in individuals with obesity that result in a blunted exercise response.