bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dietary Sugars, bacterial colonization and the behavior of fruit flies
Authors: Wu Janina L. , Cao Xixi , Yang Chan 
Published: April 2020

Cavity remains prevalent in young children today. One major contributor is the modern diet, specifically the large amounts of dietary sugars consumed. Another key factor is bacteria in our mouth that eat these sugars. Streptococcus mutans among other acid producing bacteria is one of the leading microbes that initiate and promote cavity (tooth decay). It metabolizes sugars to produce plaque, which can build up over time and simultaneously increase acid production that causes cavity. So studying how quickly different sugars affect Streptococcus mutans colonization is important to understand the development of cavity and its impact on host behavior. My hypothesis was that S. mutans breaks down some sugars more efficiently and as a result, can colonize more quickly with some than others and produce more acid, thus impacting host behavior.To study bacterial colonization, I used a fruit fly model because fruit flies like sugars and Streptococcus mutans can readily colonize fruit flies when is mixed with sugars. Each sugar solution was mixed with green fluorescent protein (GFP) labeled S. mutans and fed fruit flies. We then waited for 6 days to let flies eat and grow at room temperature. After this incubation period, we took flies out every 2 days to image the green color under the fluorescent microscope, which indicates S. mutans colonization. On the final day, we took all of the remaining flies, ground them up, and performed appropriate dilutions to plate and count bacterial colonies, which represents bacterial colonization of flies. Colonization of flies fed with five different sugars by S. mutans was monitored by direct imaging and counting bacterial colony forming units. Flies fed with sucrose exhibited the best colonization, while flies fed with xylitol did not show any colonization. The pH values of S. mutans cultures (pH adjusted to 7.5) fed with different sugars were monitored using a pH meter. With all sugars, the pH dropped significantly after five minutes. The pH dropped below 4.5 with sucrose that supports the best colonization. The pH dropped at an average of 2.91 during the 30 minutes testing period, suggesting sugars and bacteria fuel acid production.Furthermore, flies colonized by S. mutans fed with sucrose were monitored for their behavior (locomotion) using beam breaks and analyzed by DAMsystems308 software. Sucrose fed flies exhibited more bacterial colonization and became hyperactive. Overall the data indicated that S. mutans utilizes some dietary sugars more efficiently and as a result, can colonize better, produce more acid and become more active. Our studies demonstrated that the interactions between bacteria and sugars are important for the development of cavity and impact host behavior.
TMAO Activates Carotid Endothelial Inflammasomes Leading to Enhanced Neointimal Formation in Nlrp3 Mice
Authors: Boini Krishna M. , Puchchakayala Goverdhan , Zhang Yang , Koka Saisudha 
Published: April 2020

Recent studies have shown that gut microbial metabolite, trimethylamine‐N‐Oxide (TMAO), is a biomarker for atherosclerosis. However, the mechanisms of how TMAO induces atherosclerosis are still unclear. The present study tested whether TMAO induces Nlrp3 inflammasome activation and consequent endothelial injury leading to atherosclerotic lesion development in the carotid arterial wall. Confocal microscopy showed that colocalization of Nlrp3 with ASC significantly increased in the intima of the carotid arteries of TMAO‐treated Nlrp3+/+ mice, suggesting the formation of Nlrp3 inflammasomes in the endothelium of these arteries. In Nlrp3−/− mice, however, such colocalization was much less detected. In consistent with inflammasome formation, TMAO‐induced IL‐1β production in the intima was abolished in Nlrp3−/− mice. Furthermore, we found that TMAO treatment decreased ZO2, VE‐cadherin and occuludin expression in carotid arteries of Nlrp3+/+ mice but not in Nlrp3−/− mice, signifying tight junction disruption in the carotid arteries of Nlrp3+/+ mice. In addition, we found that TMAO treatment had significantly increased vascular permeability to intravenously injected Evans blue dye compared to vehicle treated Nlrp3+/+ mice. However, such TMAO‐induced vascular permeability was attenuated in Nlrp3−/− mice, suggesting that Nlrp3 inflammasome activation plays an important role in TMAO‐induced vascular leakage in mouse hearts. Furthermore, we also found that TMAO markedly increased neointimal formation in partially ligated left carotid arteries (PLCA) of Nlrp3+/+ mice. However, such TMAO‐enhanced neointimal formation and increased I/M ratio in PLCA was markedly attenuated in Nlrp3−/− mice. These results suggest that the formation and activation of NLRP3 inflammasomes by TMAO may be an important mechanism in initiating endothelial inflammatory response leading to arterial inflammation and endothelial dysfunction and consequent atherosclerosis in mice.Support or Funding InformationR01DK104031 and R56HL143809
Translation Initiation Rates Govern Protein Self‐Assembly In Vivo
Authors: Halfmann Randal , Venkatesan Shriram , Wu Jianzheng 
Published: April 2020

Living proteomes are necessarily far from equilibrium. Otherwise cells could not use the energy released by phase separation to organize protein activities in space and time. It is paradoxical, then, that reducing protein influx into the proteome ‐‐ which should promote equilibration ‐‐ instead prolongs the lives of organisms from yeast to human. We therefore reasoned that kinetic barriers must exist to delay equilibration, and that these decrease with protein influx. We further hypothesized that the probabilistic nucleation of protein self‐assemblies ‐‐ or deposits ‐‐ could underlie those barriers. To investigate the effects of influx on protein deposition, we probed phase boundaries and nucleation barriers for structurally diverse protein assemblies at different rates of translation initiation in living cells. We discovered that at protein concentrations that were globally supersaturated with respect to deposition as amyloids or other ordered phases, rapid translation promoted nucleation and thereby equilibration of that protein. We tentatively attribute this effect to unexpectedly slow diffusion of proteins away from sites of translation. The resulting local accumulation appears to facilitate protein clustering into nucleation competent multimers, even at global concentrations that are subsaturated with respect to liquid‐liquid phase separation. Finally, we show that longevity‐enhancing reductions in global protein initiation, as occur during stress responses or calorie restriction, similarly sharpen phase boundaries and nucleation barriers. Together, these observations suggest that living proteomes are supersaturated with respect to highly ordered, collectively lethal deposits.Support or Funding InformationThis work was funded by NIH Director’s Early Independence Award DP5‐OD009152, NIH grant P30 AG035982, and the Stowers Institute for Medical Research.
Neurochemical Substrates of Menthol Actions in Reward‐Addiction Brain Areas.
Authors: Davila-Garcia Martha Isabel , Wang Paul , Lin Stephen , Dekhordi Ozra 
Published: April 2020

Menthol, a commonly used flavoring additive in cigarettes has been found to facilitate smoke initiation and nicotine addiction. Menthol masks the harshness of nicotine, increases its absorption, and provides a cooling sensation that appeals to many smokers. In addition to its peripheral sensory impact, recent studies have demonstrated the presence of menthol in the CNS after in vivo exposure. This implies that menthol may also impact nicotine addiction through central mechanisms. In the present study in mice, we hypothesized that dopaminergic and GABAergic neurons of the reward‐addiction circuitry are among the initial targets of acute menthol in the CNS. We tested this hypothesis by utilizing c‐Fos immunohistochemical technique together with double labeling to identify anatomical location of menthol activated cells with respect to tyrosine hydroxylase (TH) immunoreactive (TH‐IR) dopaminergic and GAD67‐GFP positive GABAergic cells. Menthol (80 mM, IP), produced c‐Fos activation at multiple sites of the mesocorticolimbic reward‐addiction pathways including several structures previously shown to be activated by nicotine such as the periaqueductal gray (PAG), dorsal raphe (DR), ventral tegmental area (VTA), amygdala, nucleus accumbens (NAcc), anterior olfactory nucleus (AON) and cingulate‐orbitofrontal cortex (A25/MO). However, none of the dopaminergic neurons in VTA, PAG/DR region or hypothalamus were activated by IP administration of menthol. Moreover, GABAergic cells of VTA, NAcc, or A25/MO were not the initial targets of menthol at these sites. In summary, the present study identifies several sites, including those of the mesocorticolimbic reward‐addiction pathways that are activated by acute IP administration of menthol, however, none contained dopaminergic and GABAergic neurons.Support or Funding InformationThis work was supported by grants from Charles and Mary Latham Funds and Howard University Bridge Funds and Pilot Study Awards Program (BFPSAP). The authors acknowledge use of the resources provided by the National Institute on Minority Health and Health Disparities of the National Institutes of Health under Award Number G12MD007597.
Geldanamycin Alters Abundance and Composition of Low Molecular Weight Proteins and Multiprotein Complexes as Observed by Size Exclusion Column Chromatography
Authors: Sherwood Susannah , Murphy Patrick 
Published: April 2020

Size exclusion chromatography (SEC) is a commonly used and minimally disruptive liquid chromatography‐based technique that separates unbound cytosolic proteins and multiprotein complexes according to their perceived molecular weights. The purpose of this project was to develop a method using SEC to partially purify and isolate biomolecular complexes, including those containing the essential molecular chaperone protein hsp90, in the presence and absence of the hsp90 inhibitor geldanamycin. Using an automated SEC program and S‐200 column, unbound proteins and protein complexes of differing molecular weights were isolated from reticulocyte lysate incubated in the presence and absence of geldanamycin. In addition to hsp90 eluting in a complex of ~250–300 kDa, consistent with it being part of a multiprotein chaperone machinery, other predominant protein elution peaks corresponded to ~26 kDa and ~16 kDa. Interestingly, incubating cell lysate with geldanamycin depleted nearly all of the ~26 kDa peak, indicating an unexpected hsp90 effect. Continued examination of eluate fractions from + and − geldanamycin‐incubated lysates has allowed us to further characterize these geldanamycin‐sensitive low molecular weight proteins as we examine the multitude of intracellular hsp90 functional activities.Support or Funding InformationFunding was provided by the Seattle University College of Science & Engineering undergraduate research program.
Glutamatergic Neurotransmission at Rat Phrenic Motor Neurons
Authors: Mantilla Carlos B. , Rana Sabhya , Zhan Wen-Zhi , Sieck Gary C. 
Published: April 2020

Glutamatergic (Glu) synaptic inputs at phrenic motor neurons (PhMNs) predominantly comprise descending axons from respiratory centers in the ventrolateral medulla. Descending synaptic inputs provide the drive for inspiratory as well as various other behaviors that result in higher force generation. We recently examined pre‐synaptic Glu terminals (VGLUT1 and VGLUT2‐positive) around the somal membrane of PhMNs grouped according to size using a robust confocal imaging‐based technique and semi‐automated image processing, and found an ~10% higher density of Glu terminals at PhMNs in the lower tertile of somal surface area. In parallel studies, we determined the density of AMPA and NMDA mRNA expression in PhMNs grouped according to size, and found that PhMNs in the lower tertile of somal surface area display ~25% higher density of AMPA (Gria2) and NMDA (Grin1) mRNA expression compared to PhMNs in the upper tertile of somal surface area. Assuming an orderly recruitment of motor units based on their intrinsic electrophysiological properties, PhMNs in the lower tertile of somal surface area are likely recruited first in order to accomplish lower force behaviors necessary for inspiration in normoxic as well as in hypoxic (10% O2) and hypercapnic (5% CO2) conditions. Thus, differences in glutamatergic neurotransmission across PhMNs of increasing size support the orderly recruitment of motor units, promoting recruitment of fatigue resistant units for inspiratory behaviors. In adult male rats, unilateral C2 hemisection (C2SH) abolishes inspiratory‐related diaphragm muscle (DIAm) activity ipsilateral to injury, but DIAm activity during higher force behaviors persists, reflecting the contribution of spared inputs, likely contralateral. Accordingly, we hypothesized that C2SH primarily disrupts Glu synaptic inputs to smaller PhMNs, whereas Glu synaptic inputs to larger PhMNs are preserved. By 7 days following unilateral C2SH, there was a ~45% reduction in ipsilateral Glu synaptic input to PhMNs compared to a ~20% reduction contralaterally. Ipsilateral to C2SH, there was an ~60% reduction in presynaptic Glu terminals at PhMNs in lower tertile of somal surface area compared to ~30% reduction at PhMNs in the upper tertile of size. Contralateral to C2SH, the reduction in presynaptic Glu terminals was similar across PhMNs grouped according to somal surface area. These results are consistent with a more pronounced effect of C2SH on inspiratory behaviors of the DIAm, and the preservation of higher force behaviors after C2SH. These results also indicate that Glu synaptic input to PhMNs varies depending on motor neuron size and likely reflects different motor control, including possibly distinct central pattern generator and premotor circuits, onto PhMNs recruited for motor behaviors with varying levels of force generation.Support or Funding InformationNIH Grants R01 HL96750 and HL146114
Neural‐Like Plasticity in Airway Epithelia
Authors: Reznikov Leah R. , Liao Yan-Shin , Guevara Maria 
Published: April 2020

Many cells exhibit plasticity. In neurons, plasticity is associated with learning and memory. Here we describe plasticity in epithelia similar to neurons. In neurons, a strong or repeated stimulus often results in enhanced release of neurotransmitters via a process known as sensitization. We discovered that intra‐airway acid challenge in pigs resulted in a sensitization‐like augmentation of mucus secretion in airway epithelia that persisted in vitro. Treating airway epithelia from normal pigs with neurotransmitter secretagogues in vitro also induced a long‐lasting augmentation of mucus secretion. Inhibition of protein synthesis or cAMP‐responsive element‐binding (CREB) protein, which are required for neuronal memory, prevented secretagogue‐mediated increases in mucus secretion in airway epithelia, whereas inhibition of CREB in vivo mitigated some features of acid‐induced sensitization. These observations suggest new properties of airway epithelia that require further characterization and might be of critical importance in airway health and disease.Support or Funding InformationR01HL153730 and OT2OD023854
Sheathing the Hybrid Cleaver: Exploring Substrate‐Envelope‐Guided Drug Design with HIV‐1 RNase H
Authors: Wilcox Abigail E. , Cota Ahnika , Woodson S. Alice , Shor Audrey C. 
Published: April 2020

Since the start if the epidemic in 1981, nearly 75 million people have been infected with the Human Immunodeficiency Virus (HIV). Despite significant medical advancements scientist have yet to find a cure for the disease and its subtypes. Many patients are treated with the FDA approved HAART (highly active antiretroviral therapy), in which several antiretroviral are given in attempt to control HIV reproduction and its quickly mutating enzymes. The advanced adaptability of the virus emphasizes the need for novel approaches to be taken to develop antivirals that are more robust in preventing drug resistance. We sought to investigate the strategies of substrate‐envelope‐guided design by studying variants of HIV‐1 RNase H. RNase H is an endonuclease that cleaves RNA from the RNA/DNA hybrids formed during reverse transcription of the viral genome. The approach taken to complete this study included considering RNase H structure, function, and mechanism. Variants were categorized and mapped to the structure of the enzyme. Resistance variants that extended beyond the substrate envelope were excluded in developing the proposed substrate envelope to target for inhibitor design. Applying the substrate‐envelope hypothesis developed by Dr. Cynthia Schiffer’s lab group afforded consideration of the method, while acquiring an advanced understanding of the structure and function of this significant domain within the larger, complex reverse transcription enzyme of HIV. Furthermore, RNase H active site serves as an emerging target of next generation therapeutic targets for treatments of HIV. Studying the evolutionary dynamics of this adaptive virus should be considered for the rational design of potent inhibitors of this protein, significant to HIV reproduction.Support or Funding InformationThe CREST Project is funded by NSF‐DUE 1022793 and NSF‐DUE 1323414.
SPARC: A Road Map for Vagus Nerve Stimulation: Evidence of Vagotopy in a Swine Model
Authors: Settell Megan L. , McConico Andrea L. , Nicolai Evan N. , Knudsen Bruce E. , Shoffstall Andrew , Ross Erika K. , Pelot Nicole A. , Grill Warren M. , Johnson Aaron J. , Ludwig Kip A. 
Published: April 2020

Cervical vagal nerve stimulation (VNS) is an FDA approved treatment for epilepsy and depression and is currently being evaluated for treatment of numerous other disorders including pain, anxiety, and inflammation. VNS also received European market approval for heart failure, bronchoconstriction, and diabetes; however, approval for these indications was based on studies in animals, such as dogs and rats, whose vagal nerve size may not have been representative of humans. When subjected to double‐blinded, randomized, sham controlled studies for subsequent U.S. approval, many of these CE‐marked VNS indications failed to meet their primary efficacy endpoints. More than 100,000 patients have undergone VNS, but despite the efficacy of vagal nerve stimulation in a subset of patients, many fail to reach stimulation levels that result in alleviation of symptoms without triggering unwanted side effects. Post hoc studies of the patient population suggested that VNS may not engage the intended fiber pathways in humans, despite engagement in preclinical studies in mouse, rat, or dog. Stimulation parameters were limited in these studies as higher parameters caused side effects such as cough, voice alteration, and dyspnea. Discrepancies between stimulation amplitude needed for intended effect versus unwanted side effect could be directly related to the relative size of the vagus nerve across animal models, variations in fascicle organization, or variations in branching patterns.To address translating improvements in VNS from the lab to the clinic, we evaluated the swine as a potential model for approximating the clinical environment. The size and fascicular organization of the swine vagus nerve is more representative of the human nerve than previously used models. We used a combination of histology, microdissection, and ultrasound to establish a distinct bimodal organization of groups of fascicles stemming from one large fascicle at the inferior (nodose) ganglion, an organization we have termed ‘vagotopy’. We demonstrated that with the use of ultrasound we can visualize the fascicular organization in vivo, an approach that could be used clinically to target stimulation of either sensory fibers or parasympathetic efferents, depending on therapeutic intent. These advances in a clinically relevant model not only inform electrode placement for target engagement, but provide an approach for reduction of side effects.Support or Funding InformationAcknowledgementsFunded by TL1TR002380 andThe Defense Advanced Research Projects Agency (DARPA) Biological Technologies Office (BTO) Targeted Neuroplasticity Training Program under the auspices of Doug Weber and Tristan McClure‐Begley through the Space and Naval Warfare Systems Command (SPAWAR) Systems Center with (SSC) Pacific grants no. N66001‐17‐2‐4010, and the NIH SPARC Program Award OT2 OD025340.
Investigating the effects of Progressive Right Ventricular Remodeling on Systolic and Diastolic RV Function in a Longitudinal Animal Model Study of Pulmonary Arterial Hypertension
Authors: Kwan Ethan Dillon , Zhang Xiaoyan , Velez-Rendon Daniela , Stowe Jennifer , Valdez-Jasso Daniela 
Published: April 2020

Pulmonary Arterial Hypertension (PAH) is a progressive vasculopathy which increases pulmonary vascular resistance and induces a pressure overload on the right ventricle, however the mechanisms by which the RV adapts to pressure overload is not well understood
. The purpose of this study was to characterize the mechanistic progression of earlier‐stage right ventricular compensated remodeling in an animal model of PAH. In a longitudinal study of the Sugen‐Hypoxia animal model of PAH, invasive RV catherization measurements were used to assess right heart function, including RV pressure and volume relations, hemodynamic parameters, and systolic and diastolic elastance measures. Because RV ejection fraction has been found to be transiently maintained in early stage remodeling, this study also sought to distinguish the contributions of systolic and diastolic volume preservation or increases in stroke volume to this maintenance
. To elucidate the mechanistic contributions to changes in organ‐level cardiac function over the course of PAH progression, a computational model was developed to differentiate between contributions due to RV geometric remodeling such as chamber dilatation and wall thickening from contributions due to intrinsic sarcomere changes such as myocardial contractility. Over the course of PAH progression, pulmonary vascular resistance and end systolic and end diastolic pressures continuously increased, while end systolic and diastolic volumes seemed to maintain. Ejection fraction and stroke volume also seemed to maintain over this period of compensated RV remodeling. Computational model analysis of RV myocardial wall mechanics and RV geometry seemed to indicate that changes in sarcomere mechanical properties were required to predict both end‐systolic and end‐diastolic PV relations throughout the study time points. Passive material parameters increased between early weeks 3–4 to mid weeks 5–6 to late weeks 8–10. Active material parameters indicated that large increases in myocardial inotropy, in part due to increases in intracellular calcium concentration and sarcomere length, occurred in order to maintain RV compensation after four weeks, and remained high through ten weeks. Ongoing biochemical analysis and tissue mechanical testing of the extracellular matrix indicate that significant contribution of fibrotic collagen deposition and stiffening of the ECM in the later weeks may explain increase in diastolic stiffness. Distinguishing between the specific mechanistic contributors to RV compensated remodeling can help identify the mediators of the transition between early stage compensated RV remodeling and later stage decompensated RV remodeling.Support or Funding InformationNational Institutes of Health NHLBI 1T32HL 105373