bluuebunny/crossref_metadata_2025_split huggingface dataset:
A NIRS‐derived Skeletal Muscle Oxygen Consumption Method Accurately Reflects the Gold Standard Direct Fick Method during Single‐leg Knee Extension Exercise
Authors: Craig Jesse C. , Broxterman Ryan M. , Barret‐O'Keefe Zachary , Wray D. Walter , Barstow Thomas J. , Richardson Russell S. , Trinity Joel D. 
Published: May 2022

BackgroundQuantifying the oxygen consumption (V̇O2) of skeletal muscle, which represents the largest metabolically‐active tissue mass, is an important assessment in exercise physiology. The gold standard for quantifying muscle V̇O2 in the exercising human is the direct Fick method, however, technical challenges (e.g. arterial catheter insertion) preclude the widespread use of this technique, justifying the need for alternative approaches for the quantification of muscle V̇O2. Recently, we developed a noninvasive method of quantifying muscle V̇O2 using Doppler ultrasound measurements of blood flow (Q̇) and near‐infrared spectroscopy (NIRS)‐derived deoxygenated‐[Heme] in a modified Fick method calculation, but, to date, this has not been validated against the gold standard method.Purpose and HypothesesTherefore, the purpose of this investigation was to compare NIRS‐derived and direct Fick quantification of muscle V̇O2 at multiple levels of single‐leg knee‐extensor exercise. We tested the hypotheses that: 1) the muscle V̇O2 assessed by direct Fick and the NIRS‐derived muscle V̇O2 would not be statistically different from each other across work rates, and 2) the V̇O2 assessed by the two techniques would be strongly related.MethodsSeven healthy young volunteers (3 women, 4 men; 24 ± 5 years) performed an incremental work rate test on a dynamic single‐leg knee‐extensor ergometer. Measurements of femoral artery Q̇ (Doppler ultrasound), vastus lateralis deoxygenated‐[Heme] (NIRS), and femoral artery and vein oxygen content were taken at rest, 0, 5, 10, 15, and 20 Watts (W) and used to estimate direct Fick and NIRS‐derived muscle V̇O­2.ResultsNIRS‐derived V̇O2 was not different from direct Fick V̇O2 at any point (rest: 45 ± 21 vs 25 ± 17 ml/min; 0 W: 153 ± 70 vs 133 ± 68 ml/min; 5 W: 188 ± 81 vs 160 ± 65 ml/min; 10 W: 242 ± 123 vs 214 ± 91 ml/min; 15 W: 279 ± 131 vs 247 ± 89 ml/min; 20 W: 343 ± 163 vs 319 ± 122 ml/min; all P = 0.26 – 0.44). Muscle V̇O2determined by the two techniques was strongly related (r2: 0.97 ± 0.03) with a slope of 1.1 ± 0.3 and Y‐intercept of ‐21 ± 22 ml/min.DiscussionTaken together, these findings indicate that the NIRS‐derived, noninvasive assessment of skeletal muscle V̇O2 accurately reflects the gold standard quantification of muscle V̇O2over a range of work rates (with a constant ≍20 ml/min offset). This investigation provides the first evidence to support the use of the NIRS‐derived muscle V̇O2 estimate during free‐flow conditions (i.e. not using venous or arterial occlusions like previous work), introducing a novel, noninvasive technique to quantify exercising skeletal muscle V̇O2.
Intermittent Hypoxia Promotes the Development of Abdominal Aortic Aneurysm in Male Mice
Authors: Sharma Neekun , Power Gavin , Soares Rogerio N. , Ramirez‐Perez Francisco I. , Khalyfa Abdelnaby , Gozal David , Martinez‐Lemus Luis A. , Manrique‐Acevedo Camila , Padilla Jaume 
Published: May 2022

IntroductionIntermittent hypoxia (IH) is one of the hallmarks of obstructive sleep apnea (OSA). OSA is highly prevalent among patients with abdominal aortic aneurysm (AAA). However, it remains unknown whether IH is a risk factor for the development and faster expansion of AAA. The goal of this study was to determine whether exposure to chronic IH mimicking OSA increases the susceptibility to angiotensin (Ang) II‐induced AAA in mice.MethodsFour‐ to six‐week‐old male C57BL/6 mice (n = 20/group) were subjected to IH (6.5%‐21% O2, 90 s/cycle, 12 h/day during daylight) or room air (21% O2, 24 h/day) for 6 months. During the final 14 days of IH or room air (RA) exposures, 10 mice from each group were infused with Ang II (1000 ng/kg/minute) using a subcutaneously implanted osmotic minipump to induce AAA. Sham surgery was performed in control mice (n = 10/group). Outcome was assessed by transabdominal ultrasound imaging of the abdominal aorta using a Vevo 2100 imaging system followed by histopathological examination.ResultsUltrasound imaging revealed increased abdominal aortic diameter in RA mice following Ang II infusion compared to sham mice. Exposure to IH significantly augmented the Ang II‐induced increase in aortic diameter and incidence of AAA compared to RA Ang II mice. Histologically, IH along with Ang II infusion augmented medial elastin depletion and accumulation of collagen in the aorta. Additionally, IH was also associated with the pathological process of extensive matrix degradation as evidenced by increased matrix metalloproteinase (MMP9) and a disintegrin and metalloproteinase (Adam)17 expression in the aorta following Ang II infusion.ConclusionsIH exposures simulating OSA promote the development of AAA. Clarification of the underlying molecular mechanisms may reveal novel therapeutic targets for the management of AAA.
Characterizing the Capacity of Acinetobacter calcoaceticusto Grow in Intestinal Conditions and Modulate the Gut Epithelium
Authors: Glover Janiece S. , Browning Brittney , Ticer Taylor , Engevik Amy , Engevik Melinda 
Published: May 2022

BackgroundAcinetobacter species can occupy several ecological niches, including the mammalian intestine. Acinetobacter has been identified in the human fecal microbiota and it is speculated that the gut can serve as a reservoir for this pathobiont. The Acinetobacter calcoaceticus–Acinetobacter baumannii complex is a common cause of drug‐resistant pneumonia, urinary tract, skin and soft tissue infections. A. calcoaceticus has been considered to have relatively low virulence compared to its counterpart A. baumannii since colonization is more frequently noted more than infection clinically. However, few studies have dissected the interaction between A. calcoaceticus and the host, particularly in the gut. In this study, we sought to examine the ability of A. calcoaceticus strains to survive environmental stressors found in the gut. We also examined the reciprocal interactions of A. calcoaceticus strains on the host using colonic organoids.Methods & ResultsThree commercially available strains of A. calcoaceticus and four clinical isolates were grown aerobically in brain heart infusion (BHI) media, subcultured in a fully defined bacterial media termed ZMB1 and exposed to various concentrations of NaCl, ethanol, bile salts and pHs that were designed to mimic the gut. All A. calcoaceticusstrains grew robustly at NaCl concentrations that mirrored the small intestine, but differences were observed between strains at higher NaCl concentrations. Additionally, all strains grew well at pH 7 and pH 6, and exhibited growth reduction at pHs 5 and 4. All strains tolerated several concentrations of bile salts and ethanol; suggesting tolerance for intestinal stressors. Incubation of live A. calcoaceticus strains with inside‐out jejunum and colonic organoids significantly increased pro‐inflammatory cytokines (IL‐1α, KC/IL‐8, MCP‐1 and TNF) and decreased MUC2 and MUC13 transcripts, without altering tight junctions.ConclusionsCollectively, these data demonstrate that A. calcoaceticus is well adapted to the gastrointestinal tract and points to the potential for Acinetobacter to influence the gut epithelium. Of note, we observed differences between lab adapted strains and clinical isolates, highlighting strain variation and indicating that clinical isolate strains should be incorporated into future work.
Elucidating the antibiotic sensing mechanism of VanB vancomycin‐resistant Enterococci
Authors: Rotsides Photis , Maciunas Lina J. , Lee Paula , Webber Nakoa , Beld Joris , Loll Patrick J. 
Published: May 2022

The antibiotic vancomycin is used as a last resort to treat persistent infections caused by Gram‐positive pathogens. Vancomycin kills bacteria by binding a peptidoglycan precursor, thereby inhibiting cell‐wall biosynthesis. An alarming type of resistance to this antibiotic comes in the form of vancomycin‐resistant Enterococci(VRE). VRE have acquired genes that allow them to remodel the cell‐wall precursor and prevent vancomycin binding. Expression of these remodeling genes is under control of the VanSR two‐component system. VanS is a membrane‐bound sensor kinase that recognizes the vancomycin signal, and in response activates the transcription factor VanR, which activates expression of the remodeling genes. However, very little is known about how VanS senses the antibiotic.To date, nine different types of VRE have been discovered, with VanA and VanB types responsible for the vast majority of human infections. Since vancomycin can induce the expression of both VanA and VanB resistance genes, we hypothesize that the VanS proteins from these types are activated by directly binding to vancomycin. We used in vitro autokinase assays to show that vancomycin directly activates VanS from VanB VRE (VanSB), while having no direct effect on VanSA­. We isolated the VanSB periplasmic sensor domain and used fluorescence anisotropy to show that it directly binds to a fluorescent vancomycin analog. Computational modeling predicts that the VanSB sensor domain adopts a PAS‐like fold, and HDX‐MS experiments supported this prediction and identified a potential vancomycin‐binding site. We also developed vancomycin photoprobes to confirm this binding site and to elucidate vancomycin’s orientation in the interaction. These results demonstrate how VanSBcan directly sense vancomycin in the environment to activate the resistance mechanism in VanB VRE, providing a promising therapeutic target to combat these dangerous pathogens.
Enhanced Isolation of Single Myofibers in Flexor Digitorum Brevis Dissociation
Authors: Moore Logan , Awad Kamal , Mo Chenglin , Huang Jian , Wang Zhiyang , Brotto Leticia , Brotto Marco 
Published: May 2022

IntroductionThe isolation of single myofibers from the Flexor Digitorum Brevis (FBD) has been a well‐established model in skeletal muscle physiology research. The use of isolated single‐fibers has led to advancements in the understating of the excitation – contraction (E‐C) coupling mechanisms in skeletal muscle, calcium transients, the role of mitochondria, and much more. However, these experiments rely on the quality of the dissociation of myofibers and their attachment to the imaging dish which can be difficult and time exhaustive. The purpose of this study was to build upon previously established methodologies to improve the yield of intact‐alive myofibers in a time efficient manner.Methods and MaterialsEuthanasia and experimental protocols were approved by the University of Texas at Arlington’s IACUC. Based upon previously established dissociation techniques (1–3), we modified the protocol as follows: the intact FDB was dissected out and placed in 2 mL of Ringer’s solution (142 mM NaCl2, 5 mM KCl, 1.8 mM MgCl2, 10 mM Hepes, 10 mM Glucose). Under the dissection microscope the whole muscle was separated into 4 muscle bundles; separated by the distal tendons. The muscle bundles were transferred to the digestion media (DMEM with glutamine, 2% sterile filtered fetal bovine serum (FBS), 0.1% gentamycin, and 4 mg ml‐1 Collagenase A). The muscle bundles were incubated for 30‐45 minutes at 37° C in 5% CO2. Following incubation, the bundles were transferred to 1mL of Ringer’s solution in a 24‐well plate and gently titrated with the cut end of a P1000 pipette tip. The solution was transferred to laminin coated glass bottom dishes and incubated for 15‐30 minutes for fiber attachment. Following fiber attachment, the fibers were either stained with the LIVE/DEAD™ Viability/Cytoxicity kit or loaded with Fura‐2 AM fluorescent dye for measurement of maximal calcium depolarization response induced with 100mM Potassium Chloride (KCl) using a PTI spectrophotometry system.Results and ConclusionWe found that using an increased concentration of collagenase and a reduced time of digestion successfully increased the number of fibers in the field of vision.. Laminin coated glass bottom dishes produced quick and strong attachment, allowing for optimal stimulation conditions. The use of cell culture media with FBS protected the sarcolemma increasing the viability of the fibers. This is shown in both the LIVE/DEAD imaging and the response to KCl stimulation. This study demonstrates that the change of dissociation media and the decrease in dissociation time allow for protection of the myofiber for an increased yield and viability. This protocol will allow for improved experimental outcomes in which mature myofibers are subjected to electrical or chemical stimulations.References1. Calderón et al. JMRCMdoi: 10.1007/s10974‐009‐9181‐1.2. Capote et al. JP doi: 10.1113/jphysiol.2004.081034.3. Yi et al. JBC doi: 10.1074/jbc.M110.217711.
Inulin Modulates Iron Metabolism in Piglets Fed a High‐Iron Milk Formula
Authors: Park Jungjae , wickramasinghe Yapa , Kalanetra Karen , Mills David A. , Ji Peng 
Published: May 2022

ObjectiveIron‐fortified formula provides excessive amount of iron compared to breast milk, and there is a rising concern over the adverse effects of dietary iron overexposure at infancy. The study aimed to evaluate the effect of dietary prebiotics and synbiotics supplement on iron absorption and metabolism in a milk‐fed neonatal piglet model.MethodsOn postnatal day (PD) 2, piglets (n = 6/treatment) were blocked by sex and body weight (BW) and randomized to the following dietary treatments: 1) an iron‐adequate milk formula with 60 mg Fe/kg milk solid (AI), 2) a high‐iron milk formula with 480 mg Fe/kg milk solid (HI), 3) the HI formula supplemented with inulin (Orafti®IPS, Beneo) at 6% of milk solid (HIP), 4) the HIP formula with an oral supplement of 5 ml of Lactobacilus agilis YZ050 (L. agilis) at 1x109 CFU/ml once in every 3 days (HIS). Pigs were fed at 270 mL of milk/kg BW in 14 meals daily through an automatic programmable milk delivery system. Blood and fecal samples were collected on PD 1, 7, 14, 21, 28. On PD 28, piglets were euthanized, and tissue samples were collected. Tissue and fecal samples were analyzed for iron concentrations using flame atomic absorption spectrophotometry analysis. Blood samples were analyzed for hemoglobin (Hb) using Drabkin’s reagent and hematocrit (Hct) using Unico Micro‐hematocrit centrifuge. The mRNA expression of iron transporters and regulatory proteins in the intestinal tissues were determined by RT‐qPCR. Data were analyzed for one‐ or two‐way ANOVA with repeated measure for variables measured over time. Statistical significance was declared at P ≤0.05.ResultsOverall growth performance of piglets across the groups showed no statistical significance during the study. Both Hct and Hb were higher in HI, HIP, HIS than in AI during the study (P≤ 0.05). In comparison with AI, high‐iron formula markedly increased fecal iron concentration on PD7, 14, 21, 28 (P≤ 0.05) with exception of the comparison between AI and HIP on PD7. Use of inulin in HIP reduced fecal iron on PD21 and 28 in comparison with HI (P≤ 0.05). High‐iron formula significantly increased hepatic iron compared to AI (P≤ 0.05), while use of inulin alone or in combination with probiotics attenuated hepatic iron accumulation in comparison with HI (P≤ 0.05). The same response was also observed in analysis of iron concentration in colon content. Duodenal iron concentration was higher in HIP and HIS than in AI (P≤ 0.05), whereas ileal iron concentration was higher in HI than in AI (P≤ 0.05). The mRNA expression of divalent metal transporter 1 (DMT1) in colon was lower in HIP compared to AI (P ≤ 0.05); duodenal cytochrome b (DYCTB) in colon was lower in HI and HIP compared to AI (P ≤ 0.05).ConclusionHigh‐iron formula resulted in hepatic iron overload and increased iron flux in the large intestine and feces. Use of inulin alone or in combination with L. agilis diminished iron deposition in liver, colon, and feces caused by consumption of high‐iron formula in piglets.
The Impact of Early Life Exposure to Glyphosate
Authors: Wang Joshua , Hara Takeo , Soto Gloria , Sasaki Masaru , Karakasheva Tatiana , Muir Amanda 
Published: May 2022

Eosinophilic esophagitis (EoE) is a chronic immune mediated disease that affects populations of all ages. It is characterized by eosinophilic inflammation of the esophageal mucosa, decreased epithelial integrity, and lamina propria fibrosis. Clinically, the symptoms of EoE can range from mild (dysphagia, abdominal pain, vomiting), to severe (food impaction, inability to thrive), to complete loss of esophageal function in extreme cases. This disease, first described in 1993, is rising in incidence and prevalence. Unfortunately, the reason for disease emergence is unknown and environmental triggers have been postulated as a potential source. The role of environmental toxins, specifically herbicides, has never been examined in the pathophysiology of atopic disease. Glyphosate, the active ingredient in Roundup, is the most used herbicide in the United States, and is frequently used as a desiccant prior to harvest. Residual amounts can be detected in harvested crops and downstream food products, potentially leading to a diet of chronic exposure. Herein we sought to determine the effects of early life glyphosate treatment and the consequences of exposure on the development of eosinophilic esophagitis and the maintenance of epithelial integrity.We exposed mice to physiologic levels of glyphosate in utero and throughout their life cycle to simulate glyphosate consumption in the typical American diet. We then induced EoE in mice using our established protocol and evaluated epithelial integrity and inflammation. Interestingly, we found that chronic glyphosate treatment alone induced a 2‐fold increase in esophageal eosinophils over baseline, similar to mice undergoing EoE. Secondarily, we exposed primary human esophageal and intestinal organoids to short term glyphosate treatment. We observed no changes in the esophageal organoids. However, we found increased gene expression of mucin 2 (MUC2) in organoids derived from terminal ileum and proximal colon.Taken together these results suggest that there is increased inflammation in the glyphosate treated mice and this may be due, in part, to a response generated in the small intestine by glyphosate exposure.
Endothelial Cell Sprouting in Coronary Collateral Growth
Authors: Juguilon Cody , Jamaiyar Anurag , Wan Weiguo , Gadd James , Enrick Molly , Wang Yang , Clark Alyssa , Chilian William , Yin Liya 
Published: May 2022

Rationale– Coronary collateral growth is a natural bypass for ischemic heart diseases. It offers tremendous therapeutic benefit, but the process of coronary collateral growth is incompletely understood due to limited preclinical murine models that would enable interrogation of its mechanisms and processes via genetic modification and lineage tracing. Understanding the processes by which coronary collaterals develop can unlock new therapeutic strategies for ischemic heart disease.Objective– To develop a murine model of coronary collateral growth by repetitive ischemia (RI) and investigate the process of coronary collateral growth in adult hearts by lineage tracing.Methods and Results– A murine model of coronary collateral growth was developed using short episodes of repetitive ischemia. Repetitive ischemia resulted in robust collateral growth in adult mouse hearts, validated by high‐resolution micro‐computed tomography. ROSA mT/mG reporter mice with Apln‐CreERT2 transgene were used for lineage tracing of sprouting endothelial cells to determine cellular contributions to coronary collateral growth. Two‐photon and confocal microscopy imaging revealed RI‐induced coronary collateral growth initiated from sprouting Apelin+GFP+endothelial cells. Newly formed capillaries in the collateral‐dependent zone expanded in diameter upon RI stimulation and arterialized with smooth muscle cell recruitment to form mature coronary collateral arteries. Notably, pre‐existing coronary arteries and arterioles were not Apelin+ GFP+, and all Apelin+endothelial cells arose from sprouting capillaries. HIF1α, VEGFR2, CXCR4, MCP‐1, and JAG1 signaling in the collateral‐dependent zone were also upregulated during coronary collateral growth.Conclusions– We developed a murine model of RI‐induced coronary collateral growth, and our data show sprouting EC contribute to coronary collateral growth in adult hearts. Sprouting angiogenesis is shown for the first time to arterialize into mature blood vessels of larger diameter in response to repetitive ischemia in adult hearts.
Effect of Sulindac in an in vitro AD Model Under hypoxic conditions
Authors: Rivera Oscar , Chen Belinda , Prentice Howard , Weissbach Hebert , Allani Shailaja 
Published: May 2022

BackgroundAlzheimer’s Disease (AD) continues to be the most prevalent form of senile dementia without any significant therapy. Oxidative damage and hypoxia are known to play a major role in the pathology of AD. Hypoxia increases production of ß amyloid (Aß) plaques and dysfunction in tau proteins which leads to neuronal death by increasing reactive oxidative species (ROS) formation. Furthermore, Aß derived from the proteolytic cleavage of β‐amyloid precursor protein (APP) acts as a biomarker of AD. It is known that in an APP transgenic mice model of AD exhibits oxidative damage suggesting that a possible therapeutic approach would be to protect neuronal cells against oxidative damage. Our laboratory has shown previously that the drug sulindac, a known non‐steroidal anti‐inflammatory drug (NSAID) can protect retinal cells and the heart against oxidative damage by initiating a preconditioning response, similar to ischemic preconditioning that is independent of its NSAID activity. The goal of the present studies is to investigate whether sulindac can protect APP‐transfected neuronal cells from oxidative damage under hypoxic conditions.MethodsWe established an AD neuronal cell line by overexpressing APP using the plasmid vector pCAX‐APP (Swe/Ind) in SHSY5Y neuroblastoma cell line. Cell proliferation was assayed in the AD cell model under hypoxic conditions using trypan blue, under normoxic and hypoxic conditions, with and without sulindac. APP overexpression in the transfected cells was analyzed via Western blot.ResultsOur results show that the plasmid DNA induced the expression of APP in transfected SHSY5Y cells compared to untransfected cells and the expression of APP was strongest at 24 h. We observed that the cell proliferation decreased in APP transfected cells in both hypoxic and normoxic conditions. Further, reduced cell proliferation was seen under hypoxic conditions compared to normoxic conditions indicating that hypoxic conditions further exacerbateAD pathology. Our findings in an in vitro AD model, suggest that sulindac has a potential therapeutic value to ameliorate AD pathology.