bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influenza A Virus Causes Shedding of the Alveolar Epithelial Glycocalyx through Activation of Sheddases
Authors: Schaaf Kaitlyn R. , Buggs Charity J. , Putz Nathan D. , Langouet‐Astrie Christophe J. , Jetter Christopher S. , Nigretti Nicolas M. , Sucre Jennifer M. S. , Schmidt Eric P. , Bastarache Julie A. , Shaver Ciara M. 
Published: May 2022

ObjectiveThe healthy alveolar epithelium is protected by a heparan sulfate rich, glycosaminoglycan layer called the epithelial glycocalyx. Our group found that the epithelial glycocalyx is shed in patients with acute respiratory distress syndrome (ARDS). In murine models of LPS‐ or bleomycin‐induced acute lung injury, sheddases (membrane‐bound enzymes that cleave extracellular potions of transmembrane proteins) are upregulated and associated with glycocalyx shedding and increased lung permeability. ARDS is commonly caused by viral infections including influenza A (IAV). In murine models, IAV causes massive and persistent glycocalyx shedding into the airspace but the mechanisms by which this occurs are unknown. The objective of this work is to determine the molecular processes underlying IAV‐induced shedding of the glycocalyx.HypothesisWe hypothesize that IAV causes glycocalyx shedding through induction of host sheddases.MethodsWe examined the literature and curated a list of sheddases associated with IAV with potential to cleave the glycocalyx (MMP‐7, ‐2, ‐9 and their inhibitors TIMP‐1 and ‐2). C57BL/6 mice were infected intranasally with A/PR/8/34 (H1N1) at 30,000 PFU/mouse and bronchoalveolar lavage and lung tissue were collected at day 1, 3, and 7 post infection. Sheddase expression was assessed by RT‐qPCR and RNAscope was used to localize lung sheddase expression in infected and uninfected lungs. MLE‐12 mouse lung epithelial cells were infected with viable or heat‐inactivated (56C for 30 min) A/PR/8/34 (H1N1) at a MOI of 1 and sheddase expression measured by RT‐qPCR.ResultsMice infected with IAV develop significant lung inflammation (increased BAL inflammatory cells), lung permeability (increased BAL protein), and increased glycocalyx shedding. MMP‐7 is upregulated in infected vs. uninfected lungs at day 1 and 3 post infection, then returns to baseline levels by day 7. MMP‐7 is only expressed in cells that are directly infected by IAV. Expression of the MMP‐7 inhibitor TIMP‐1 is similar to uninfected lungs on day 1, but increases 50‐fold on day 3. In contrast, MMP‐2 and MMP‐9, as well as their inhibitor TIMP‐2 are not upregulated in the first 7 days after IAV infection. Preliminary studies in lung epithelial cells suggest that heat‐inactivated IAV fails to upregulate MMP‐7.ConclusionsTogether, these data suggest that localized IAV infection increases MMP‐7 in a murine model of IAV infection, but has no effect on several other sheddases. This suggests that MMP‐7 may modulate IAV‐induced glycocalyx shedding. Future studies will explore the mechanisms of IAV induced glycocalyx shedding which could provide molecular targets for clinical intervention in IAV‐ARDS pathogenesis.
Beneficial effects of AT1 antagonists treatment, losartan, on cardiovascular and cognitive function on aged male Dahl salt sensitive rats
Authors: Rocha dos Santos Carla , Grigorova Yulia , McDevitt Ross , Zernetkina Valentina , Wei Wen , Juhasz Ondrej , Lakatta Edward G. , Fedorova Olga V. 
Published: May 2022

Introduction and objectiveCardiovascular diseases and hypertension are the major contributors to the pathogenesis of vascular dementia. The Dahl salt‐sensitive (DSS) rat model is characterized by age‐associated cardiovascular remodeling and the development of central arterial stiffness (CAS) in the presence of renin‐angiotensin system disbalance, accompanied by cognitive decline. We hypothesized, that the anti‐hypertensive treatment, antagonist for angiotensin II receptors losartan (LOS), via reducing CAS, will improve cardiovascular parameters and cognitive function in aged DSS male rats.MethodsMale DSS rats (n=30) were kept on a normal salt diet (0.5% NaCl) for the duration of the study. At 6 months of age, rats were given either LOS in drinking water (30mg/kg/day, n=14) or control treatment (n=16) for 6 months. Measurements, including systolic and diastolic BP (SBP, DBP) and pulse wave velocity (PWV), a measure of CAS (by echocardiology), were taken after 6 months of LOS treatment. Rats were tested in an operant chambers (OCh) attention challenge to assess attention and impulsivity; elevated plus maze (EPM) was performed to estimate anxiety‐like behavior. Statistical analyses were performed using 1‐way ANOVA, t‐test and Pearson correlation. Data are presented as mean ± SEM.Resultsfollowing 6 months of treatment, at 12‐mo of age, LOS treated rats had lower BP and PWV vs. control (Table 1). Performance on the OCh indicated that LOS rats had more correct responses vs. control rats (Fig. 1). The LOS group exhibited lower anxiety levels, because they spent less time on the closed shoulder in EPM (Table 1) and demonstrate 1.5‐fold increase of time in the open shoulder (p < 0.01). PWV and SBP was negatively correlated with time on open shoulder, total distance traveled and total correct answers at 12‐mo of age (Fig.2).ConclusionAged male DSS rats show beneficial effects of LOS on cardiovascular and cognitive function. The CAS and BP improvement by LOS was associated with improved attention and lower anxiety levels. The mechanistic basis of LOS effects on cognition via cerebrovascular and brain changes will be further investigated.
Strategically Substituted Agmatine Analogs Reduce Neuropathic Pain and Show Improved Pharmacokinetics Compared to Agmatine
Authors: Clements Benjamin M. , Peterson Cristina D. , Kitto Kelley F. , Wilcox George L. , Fairbanks Carolyn A. 
Published: May 2022

Chronic pain remains a serious issue, affecting millions in the United States. Opioids serve as the most powerful therapeutic option but show limited efficacy in neuropathic pain and consequential side‐effects, such as tolerance, addiction, and respiratory depression. Development of novel drugs to treat pain, though, continues to stagnate. Additionally, in conditions in which opioids are required, adjuvants to reduce opioid‐induced neuroplasticity is critical. Agmatine has been shown to reduce neuropathic pain behavior and opioid tolerance, but use remains limited due to potentially reduced CNS penetration due to its hydrophilicity. Therefore, we have developed a series of agmatine‐based compounds that exhibit greater lipophilicity while exhibiting equivalent pharmacological responses (Figure 1). The goal of this study was to assess differences in pharmacokinetics and dynamics of 4 of these strategically substituted agmatines (SSAs). Our hypothesis is that these compounds will have an increased plasma half‐life and CNS distribution compared to agmatine, with equivalent reductions in neuropathic pain and opioid tolerance.Analysis of the pharmacokinetics in rat plasma was done using serial sampling via jugular catheter. All in vivo experiments were reviewed and approved by the University of Minnesota IACUC and the ACURO of the Department of Defense. After intravenous administration, the SSAs exhibit 2‐phase distribution and elimination and have an increased elimination half‐life over agmatine (9 minutes), with SSA3 and SSA4 showing the longest (Table 1). This increased half‐life aligns with the increased lipophilicity of these compounds. Additionally, SSA2 and SSA4 show large volumes of distribution, suggesting increased CNS distribution.To test the impact of these compounds in vivo, we induced neuropathic pain by performing spared nerve injury (SNI). SNI drives robust tactile hypersensitivity measured using the von Frey assay in the ipsilateral hind‐paw, with the contralateral paw serving as a non‐injured control. Following intravenous administration, SSA2‐4 reduced SNI‐induced hypersensitivity at similar doses to agmatine, showing equivalent pharmacological activity. Additionally, after chronic morphine treatment alongside co‐treatment with SSA1 and SSA2, opioid reduction in the warm water (52.5°C) tail flick response was preserved, representing a prevention of opioid tolerance. In conclusion, these chemical alterations to agmatine are able to improve pharmacokinetic parameters while maintaining the pharmacological reduction in neuropathic pain and opioid tolerance, suggesting potential as novel therapeutics to replace opioids in pain treatment.
Obesity‐Induced Breathing Variability During Sleep Is Independent of Apneas and Sleep Fragmentation
Authors: Kim Lenise J. , Alexandre Chloe , Pho Huy , Latremoliere Alban , Polotsky Vsevolod Y. , Pham Luu V. 
Published: May 2022

IntroductionObesity is a major cause of sleep‐disordered breathing (SDB). Conventional metrics of SDB, such as the apnea‐hypopnea index, can be confounded by the effects of obesity on oxygenation and lack of standard definitions. Thus, the impact of SBD on sleep is often difficult to quantify. Sleep fragmentation is frequently observed in obese individuals, but whether it occurs independently of SDB remains unknown. Quantitative analysis of ventilation may delineate the effects of obesity on breathing patterns and sleep fragmentation. We aimed to examine the effects of obesity on respiratory patterns during sleep and the relationship between obesity‐related respiratory variability and sleep fragmentation.MethodsSleep recordings were performed in 15 male lean C57BL/6J mice and 17 male diet‐induced obese (DIO) mice on the same genetic background. We applied Poincaré analysis of minute ventilation (VE) during sleep to estimate the breathing variability. Apneas were scored as ≥90% reductions in airflow for two breath cycles or ≥0.7s regardless the presence of arousals. Arousals were defined as single waking events lasting less than 16s. Arousals were classified as respiratory when associated with ≥30% drops in VEfrom baseline.ResultsBreathing variability was significantly higher in DIO mice during NREM sleep, but not during REM sleep. Obesity was associated with an increased apnea severity and 45% greater sleep fragmentation. However, obesity‐induced breathing variability was not affected by apnea or arousal indexes. Respiratory arousals comprised 15% of the arousals in both strains.ConclusionsObesity increased respiratory variability during NREM sleep independently of apneas and macro‐sleep architecture. Obesity caused sleep fragmentation that was not fully explained by SDB severity. Our quantitative analysis of VE identified differences in breathing variability in obesity that were not captured by traditional SDB metrics, which may be applicable for human SDB.
Anaerobic Bacterial Biofilms Inhibit Neutrophil Responses via the Release of Stable Small‐Molecule Effectors
Authors: Lockhart Joey , Allain Thibault , Buret Andre , Morck Douglas 
Published: May 2022

Background and ObjectiveFusobacterium and Porphyromonasare two genera of opportunistic pathogens that often aggregate in complex communities known as biofilms. Host innate immune cells are frequently frustrated when they encounter biofilm bacteria, resulting in ineffectual clearance and persistent infection. Anaerobic pathogens generate or accumulate organic molecules and use them as defense against environmental pressures such as oxidative stress or attack from host immune cells. Porphyromonasspecies utilize protoporphyrin IX (PPIX) to protect against neutrophil oxidative‐killing. The objective was to develop a model of mixed‐species biofilm generation and to evaluate bovine neutrophil responses to bioactive molecules released from either biofilm or planktonic bacteria. We hypothesized that biofilm‐conditioned growth medium would contain more PPIX than planktonic medium and therefore inhibit the functional responses of peripheral neutrophils.MethodsNeutrophils were isolated from whole blood via hypotonic lysis and bacterial biofilms were generated using previously validated methods for the cultivation of mixed‐species biofilms. Spent media from biofilm and overnight planktonic cultures were collected, centrifuged, and filtered to remove viable bacteria. Supernatants were fractionated via <3kDa‐cutoff filtration and exposed directly to neutrophils. Neutrophil responses to the supernatants were assessed with a fluorescent microplate assay for reactive oxygen species (ROS) and chemotaxis was measured with a Transwell® transmigration assay. The specific mechanism of neutrophil activation was investigated by employing NF‐κB and NADPH oxidase inhibitors.ResultsNeutrophils exposed to planktonic supernatant showed significantly elevated oxidative and chemotactic responses compared to biofilm products from identical bacteria. Ultra‐filtration revealed that a <3kDa molecule is differentially expressed in the supernatants and allows biofilm‐bacteria to inhibit neutrophil responses. Intensive heat, nuclease, lipase, and protease treatment of the <3kDa fractions did not alter neutrophil functional responses. Preliminary experiments suggest that the accumulation of PPIX in the biofilm supernatant attenuates neutrophil chemotaxis and ROS production. In addition, chemical inhibition experiments indicated that neutrophils respond to planktonic supernatants independently of NF‐κB signaling.ConclusionsExperiments reveal a minimal neutrophil response to molecules released from biofilm bacteria and may explain the inadequate host response to biofilm‐mediated infections. The phenotypic changes in the biofilm mode of growth allow for the generation and accumulation of PPIX, providing protection from host immune clearance mechanisms. Understanding the mechanism of immune avoidance is a crucial step to reduce the persistent inflammation and negative clinical outcomes associated with chronic biofilm‐mediated disease.
Circulating hematopoietic stem cells (cHSC) in elite athletes: an antidoping perspective
Authors: Donati Francesco , Bonelli Cristina , Biasini Giorgia M. , Concetti Livia , de la Torre Xavier , Botre Francesco 
Published: May 2022

Hematopoietic stem cells (HSC) are multipotent progenitor cells, resident primarily in human bone marrow. Their main function is the continuous renewal of all hematopoietic cells. A small fraction of HSC is also circulating in peripheral blood (cHSC) where they can be possibly detected thanks to the application of the new very sensitive flow cytometry methodologies.In recent times it has been debated whether the utilization of several different types of stem cells can be abused by athletes for doping purposes. Moreover, there is growing knowledge that the dynamic and turnover of circulating HSC may reflect changes affecting the physiologic processes at the erythropoietic level; also, cHSC and other circulating hematopoietic progenitors (cHP) resulted to give different responses in athletes engaged in endurance and maximal exercise sports. If it is true that the use of stem cells (mainly mesenchymal stem cells) to allow a rapid recover from an injury is not considered a doping practice, it is also true that the 2022 WADA list of prohibited substances and methods forbids “the use of normal or genetically modified cells” as well as “any form of intravascular manipulation of the blood or blood components by physical or chemical means”. In this context, HSC and hematopoietic erythroid progenitors may be a potential threat and the possibility of their abuse needs to be exploited in sport antidoping.In view of the above, we have preliminarily assessed the possibility of detecting circulating hematopoietic stem cells by flow cytofluorimetry. In details, we applied two flow cytofluorimetric protocols for the accurate and precise counting of circulating HSC, also discussing the potential applicability in a potential antidoping scenario. We concluded that i) flow cytofluorimetry is a pratical and rapid platform for the identification and the counting of cHSC and other erythroid progenitors in peripheral human whole blood, ii) the correlation between CD34+ circulating progenitors and standard haematological parameters may be an effective new tool to be exploited as in direct markers of blood doping and, iii) accurate baseline levels of HSC and erythroid progenitors need to be determined in order to identify abuses of HSC and/or conventional blood doping.
Self‐DNA induced inflammation impairs the normal function of myoepithelial cells of the lacrimal gland
Authors: Yang Menglu , Dartt Darlene 
Published: May 2022

Sjögren's Syndrome (SS) is an autoimmune disease that mainly affects the lacrimal glands and salivary glands. Patients with SS suffer from severe dry eye which leads to corneal ulceration. The pathogenic nuclear acid triggered autoimmune response is playing a key role in autoimmune disease like SS. Previously our group observed a significantly higher expression of a DNA sensing mechanism Absent in Melanoma (AIM)2 inflammasome in two mice models of primary SS compared to the wildtype. AIM2 is a member of innate immune sensors that detects the presence of DNA in the cytoplasm, and then forms the AIM2 inflammasome to activate caspase‐1, which cleaves immature pro‐IL‐1ß to mature IL‐1ß that contribute to inflammation. In this study we investigate the effect of the AIM2 inflammasome DNA sensing pathway on primary myoepithelial cell (MEC) function of the lacrimal gland.Primary MECs culture was acquired from female wildtype C57Bl/6 mice aged 4‐6 weeks. Genomic DNA (gDNA) extracted from MECs was used to resemble the self‐DNA. The MECs were treated with gDNA for 6 hours, with random double‐stranded DNA poly A:T as a positive control. Immunofluorescent (IF) staining result shows the accumulation of AIM2 signals and a speck of Apoptosis‐associated speck‐like protein containing a CARD (ASC), indicating the assembly of AIM2 inflammasome in both gDNA and poly AT treated group (Fig 1). The activation of caspase‐1 by gDNA treatment was confirmed using FAM‐FLICA assay.We next determined the primary function of MECs which is contraction, under the effect of DNA‐induced cell response. A time lapse microscope was used to record a 2‐hour video of the MECs upon ATP (10‐5M) stimulation, as ATP is an important neurotransmitter released by the parasympathetic nerve end which is responsible for tear production. The first and last images will be used as a quantification study, and the reduction (%) of the area after the 2hrs period is calculated to represent the contractility. The area reduction in the gDNA as well as the positive control poly A:T treated group was significantly decreased from the non‐treated (NT) group. We next investigated the mechanism of the reduced contractility caused by DNA. One of the most important signals for muscle cell contraction is the Ca2+. We measured the change of intracellular Ca2+ concentration ([Ca2+]i) in MECs upon ATP stimulation but observed no difference between gDNA and NT group. We then determined the actin and cytoskeleton of the MECs upon DNA‐induced inflammation. The structure of ß‐tubulin which supports the cell structure, and F‐actin which enables the mobility, were investigated by IF. The result shows that the poly A:T treated group presents with higher ß‐tubulin but lower F‐actin signals compared to the control.To conclude, self‐DNA induces inflammasome formation and caspase‐1 activation in MECs, which results in the impairment of contraction by altering the cytoskeletal proteins.
Protective Effect of Hydrogen Sulphide in Cardioplegia on Global Myocardium Ischemia‐reperfusion Injury
Authors: Zuo Ji‐Yang , Hou Hai‐Tao , Liu Zhi‐Gang , Yang Qin , He Guo‐Wei 
Published: May 2022

ObjectiveThe endogenous gaseous transmitter hydrogen sulfide (H2S) is an important regulator of the cardiovascular system and is reported to have cardioprotective activity against ischemia/reperfusion (I/R) injury. We investigated the cardioprotective effect of H2S added in cardioplegia against I/R injury in global cardioplegic arrest.MethodsIsolated Wistar rat hearts were perfused in Langendorff apparatus and underwent 30 min perfusion, 120 min cold ischemia, and 90 min reperfusion. The rats were randomly divided into 5 groups: Control group, ischemic and reperfusion (I/R), St. Thomas cardioplegia (St. Thomas +I/R), St. Thomas plus H2S donor NaHS (NaHS+St.Thomas+I/R), St.Thomas plus NaHS and glibenclamide (an antagonist of KATP channel; NaHS+Glib+St.Thomas+I/R). The following indices were compared among the groups: the change of left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), heart rate, heart rhythm, and coronary blood flow. The difference in left ventricular developed pressure (LVDP), the maximum left ventricular pressure rise rate (+dp/dtmax), and the maximum left ventricular pressure drop rate (‐dp/dtmax) were also compared. Western blot was used to detect the changes of related myocardial enzymes among different groups.ResultsNaHS+St.Thomas+I/R treatment significantly improved cardiac function (LVSP, LVDP, +dp/dtmax and ‐dp/dtmax) compared to other groups (p<0.05), although no significant differences on coronary flow and heart rate were observed. After reperfusion, the frequency of ventricular arrhythmia in I/R group and St.Thomas+I/R group was significantly higher than that in NaHS+St.Thomas+I/R group. Further, the expression of cardiac Troponin T, troponin I, and creatine kinase in the NaHS+St.Thomas+I/R group was significantly lower than that in other groups (p<0.05).ConclusionCardioplegia containing H2S confers significant protection against global I/R injury during cold cardioplegic arrest. This effect is associated with opening of the myocardial KATP channels. Therefore, H2S may be a useful adjunct to cardioplegic solutions in heart surgery.
Quantitative proteomics profiling of lysine 2‐hydroxyisobutyrylation in right atrial appendage from rheumatic heart valve disease patients
Authors: Hou Hai‐Tao , Yang Qin , He Guo‐Wei 
Published: May 2022

ObjectivesLysine 2‐hydroxyisobutyrylation (Khib) is a novel acylation that regulates glycolysis. Little has been done in human diseases regarding the role of Khib. The present study was designed to reveal the role of Khib in the development of atrial fibrillation (AF) associated with heart valve disease.MethodsDiscarded right atrial appendage tissues during the cannulation procedure were collected from AF and sinus rhythm (SR) patients with rheumatic heart valve disease. The protein profiles and Khib sites were identified and qualified by Tandem Mass Tag labeling and liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) technology. Bioinformatic tools, including Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein‐protein interaction, were also used to explore the biological function between AF and SR.ResultsA total of 6,523 matched spectrum, 3,234 peptides, 2,867 modified peptides, corresponding to 579 proteins and 2,900 sites from LC‐MS/MS analysis were identified. Of these identified proteins and sites, 480 proteins and 2,275 sites were quantifiable. The length of most peptides distributed between 7 and 22, which was consistent with the length of tryptic peptides. Differentially expressed Khib sites analysis showed that there were 35 and 48 Khib sites related to 124 and 67 proteins exhibited upregulation and downregulation in AF compared to SR. Subcellular location analysis of Khib ‐related proteins revealed that cytoplasm, nucleus, and extracellular accounted for the most proportion. Bioinformatic analysis demonstrated that proteins with Khib were significantly enriched in different biological approach, such as cysteine and methionine metabolism, cGMP‐PKG signaling pathway, and glucose‐responsive energy metabolism.ConclusionsThe present study for the first time revealed larger number of differentially expressed Khib sites between AF and SR in patients with rheumatic valve disease. The proteins related to these sites are involved in diverse cellular processes including energy metabolism. These results indicate that Khib modification might be a key factor in occurrence of AF in patients with rheumatic heart valve disease.