bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unraveling the Different Network States of the Respiratory Network Using Experimental and Computational Approaches.
Authors: Bush Nicholas Edward , Baertsch Nathan , Burgraff Nicholas , Harris Kameron , Ramirez Jan-Marino 
Published: April 2020

Rhythm generation in the respiratory system must be sufficiently robust to ensure continued rhythmic activity in a variety of challenges, but flexible enough to meet the various physiological demands of the organism. The control of frequency and regularity of the respiratory rhythm critically depends on the interplay between inhibitory and excitatory synaptic activity and intrinsic membrane properties in the pre‐Bötzinger complex network. Optogenetic manipulation allows for selective control of these inhibitory and excitatory components. We find that increasing inhibitory drive during the inspiratory phase drives increases in burst frequency, whereas increasing inhibition in the inter‐burst interval decreases frequency. This frequency effect critically depends on the refractory period that is controlled by the network excitability during the inspiratory burst. The frequency is also differentially controlled by aminergic and peptidergic neuromodulators. Our experimental data indicate that Substance P increases the respiratory frequency by acting specifically on the pre‐inspiratory period. The frequency effects of opioids on the other hand depend on excitatory synaptic mechanisms and the persistent sodium current (INaP). Weakening the INaP current pharmacologically biases the network towards glutamatergic mechanisms, which increases the opioid sensitivity, while strengthening the INaP current pharmacologically or by exposing the network to hypoxia decreases the opioid sensitivity. To complement our experimental investigations of rhythm generation and neuromodulation in the respiratory network, we implement our published computational model (Harris et al. 2017, Journal of Neurophysiology). This model incorporates cell type specific and temporally constrained currents that can be used to mimic experimental manipulations such as optogenetics. This approach will provide an in silico tool to dissect and predict network responses to such manipulations.Support or Funding InformationP01 HL090554; R01 HL144801; R01 HL126523
Neurovascular Coupling is Not Attenuated During Reflex‐Mediated Sympathetic Activation via Lower Body Negative Pressure in Humans
Authors: Samora Milena , Vianna Lauro C. , Carmo Jake C. , Macedo Victor , Dawes Mathew , Phillips Aaron A. , Paton Julian F.R. , Fisher James P. 
Published: April 2020

IntroductionCerebral blood flow is tightly coupled with local neuronal activation and metabolism (i.e., neurovascular coupling; NVC). Attenuated NVC has been identified in several chronic diseases, including hypertension, but the underlying mechanism(s) remains unknown. Raised peripheral sympathetic vasoconstrictor activity can play a malevolent role in the pathology of hypertension and might also contribute to the blunted NVC as cerebral arteries are autonomic innervated. However, the role of sympathetic nervous system in the regulation of cerebral blood flow remains controversial. Given this, the purpose of the current study was to test the hypothesis that reflex‐mediated sympathetic activation via lower body negative pressure (LBNP) blunts NVC in humans.MethodsNVC was assessed using a visual stimulation protocol (5 cycles of 30 s eyes closed and 30 s of reading) in 10 young and healthy participants (3 women; aged 25 ± 3 years). In a randomized and counterbalanced order, NVC assessments were made under control conditions and during graded sympathetic activation via LBNP at −20 mmHg and −40 mmHg. Posterior (PCA) and middle cerebral artery (MCA) mean blood velocity (vmean) were determined (transcranial Doppler ultrasound). Vertebral artery blood flow (VAflow) was measured using duplex Doppler ultrasound and vessel wall tracking software. Mean arterial pressure (finger photoplethysmography), stroke volume (Modelflow), heart rate (electrocardiogram) and the partial pressure of end‐tidal carbon dioxide (PetCO2; capnograph) were obtained. Data are presented as mean ± SD.ResultsLBNP to −20 mmHg and −40 mmHg evoked an anticipated reduction in stroke volume and increase in heart rate, while mean arterial pressure was unchanged. Prior to visual stimulation, PCAvmean and MCAvmean were not different between control, −20 LBNP and −40 LBNP conditions (P>0.05), while VAflow was reduced at −40 mmHg (P=0.02 vs. control). Under control conditions, the NVC test evoked a robust increase in PCAvmean (Δ22 ± 4%), a modest increase in MCAvmean (Δ10 ± 3%), and a moderate rise in VAflow (Δ14 ± 5%). The magnitude of these responses was unaffected by LBNP at both −20 mmHg and −40mmHg (PCAvmean Δ23 ± 4% and Δ23 ± 4%; MCAvmean Δ10 ± 1% and Δ11 ± 4%; VAflow Δ15 ± 3% and Δ16 ± 6%; P>0.05). PetCO2 decreased at −20 mmHg (37.0 ± 3.1 mmHg) and −40 mmHg (36.3 ± 3.1 mmHg) LBNP trials compared to control (40.2 ± 3.7mmHg; P=0.004).ConclusionIn summary, these findings indicate that reflex‐mediated sympathetic activation via LBNP does not blunt the NVC response in healthy humans.Support or Funding InformationFunding received from Coordination for the Improvement of Higher Education Personnel (Finance Code 001) (MS), the University of Auckland (JPF, JFRP) and the Health Research Council of New Zealand (JPF, JFRP).
Exogenous lactate increases fat oxidation in resting rats
Authors: Yoo Choongsung , Kim Jisu , Kyun Sunghwan , Kreider Richard , Lim Kiwon 
Published: April 2020

BackgroundLactate had been traditionally considered a fatigue‐associated byproduct of high intensity exercise. Although several physiological roles of lactate have been revealed in the last decades, its effects on energy metabolism and substrate oxidation remain unknown. Therefore, here, we investigated the effects of lactate on the energy metabolism of resting rats.MethodsMale rats were divided into control (Con; distilled water), caffeine (Caf; 10 mg/kg), lactate (Lac; 4 g/kg), and caffeine plus lactate (Caf+Lac; 10 mg + 4 g/kg) groups. After oral administration of treatments, animals were evaluated for resting energy expenditure, biochemical blood parameters, and mRNA levels of key genes involved in energy metabolism in the soleus muscle.ResultsGroups did not differ in total energy expenditure throughout the 6‐h post‐treatment evaluation. Within the first 4 h, the Lac and Caf+Lac groups showed higher fat oxidation rates than that of the Con group. Carbohydrate oxidation rates were similar between Lac and Con groups. Lactate treatment decreased blood free fatty‐acid levels and increased the mRNA expression of fatty acid translocase (FAT/CD36) and peroxisome proliferator‐activated receptor gamma coactivator 1‐alpha (PGC‐1α) in skeletal muscle.ConclusionsOur findings indicate that lactate treatment can enhance fat metabolism in whole body and skeletal muscle.Support or Funding InformationThis paper was supported by the KU Research Professor Program of Konkuk University.
Lipid metabolism changes in C. elegans models of aging
Authors: Chan Jason P. , Radeny Joycelyn , Wang Lu 
Published: April 2020

Lipid metabolism plays major roles in cellular membrane structure and fluidity, signaling, and energy storage. Lipids have a tremendously diverse composition, structures, and saturation levels, making their cellular function complex. Recent data have suggested that presence of particular lipids correlate with aging physiology, including cardiovascular and neurodegenerative diseases. Furthermore, genetic or pharmacological manipulation of lipid enzyme function impacts aging, including lifespan and healthspan (period of life in good health). Using genetic models of aging in Caenorhabditis elegans, we performed a lipidomics study examining a panel of lipids, including free fatty acids, triacylglycerols, sphingomyelins, and other phospholipids. We measured 888 lipids, and 702 lipids were present in 80% of our samples. We tracked these lipids in 1, 5, and 10 day old adult worms, and analyzed patterns across age and mutant background. In particular, we highlight findings in a sphingolipid metabolism mutant, asm‐3 (acid sphingomyelinase), which has an increased lifespan. We compare these to physiological responses of asm‐3 mutants in response to stress. Together, we hope this analysis adds to our understanding of the biology of aging and yields novel lipid targets that may impact lifespan and healthspan.Support or Funding InformationNIH 2R15AG052933 and NIH 1S10OD021562
Structural‐Based Drug Discovery Targeting PCNA: A Novel Cancer Therapeutic
Authors: Jossart Jennifer , Kenjic Nikola , Quninoez Robert , Perry Jeff 
Published: April 2020

Proliferating Cell Nuclear Antigen (PCNA), which is a member of the sliding clamp family, critically functions as a hub for proteins that are involved in DNA metabolism events, by bringing them into close proximity with DNA. A unique isoform of PCNA has been defined as playing a critical pathological role in multiple tumors, including breast cancer and neuroblastoma. Notably, this cancer associated isoform of PCNA (caPCNA) is highly expressed in cancer cells, but not at significant levels in non‐malignant cells. Thus, we hypothesize caPCNA could act as a novel target for the development of cancer‐selective drugs. By using computer‐aided drug design (CADD) driven approaches, our collaborators at the City of Hope Medical Center have recently identified first‐in‐class small molecules capable of targeting caPCNA and killing caPCNA‐driven cancer cells. Our aim is to characterize these novel compounds by protein crystallography, to aid their development into more drug‐like molecules. Thus far, we have discovered a novel apo‐PCNA crystallization condition diffracting to 2.1 Å that can be potentially used in our analyses. We have also begun fragment‐based drug discovery (FBDD) studies, to identify novel chemical groups that could be utilized in our drug‐discovery efforts. Through thermal shift screening assays, we have revealed over 70 potential fragment binders that are undergoing structural characterizations. Thus, through combined CADD, FBDD, biochemical and cell‐based assays, our analyses of initial CADD‐based compounds and fragment hits can be used to develop compounds suitable for preclinical studies, and ideally, open a novel therapeutic avenue for the selective targeting of cancers.Support or Funding InformationDOD CDRMP BCRP Level 2 award‐ “Breast Cancer Selective Therapeutic Development: Lead Optimization of a Small Molecule Inhibitor of The Breast Cancer Selective Hub Protein caPCNA”
GDNF drives collecting duct‐like tubuloids in novel 3D in vitro system
Authors: Dixon Eryn E. , Watnick Terry , Welling Paul A. , Woodward Owen M. 
Published: April 2020

Three‐dimensional (3D) in vitro model systems have provided critical insights into the function and structure of many tissues, including lung, intestine, and brain. In recent years, the development of kidney organoids has been rapidly progressing with intricate differentiation and characterization of embryonic pluripotent and adult stem cells. These systems have significant drawbacks, including nascent phenotypes and complex differentiation of many cell types. Here, we have focused on understanding the specific cues in culture necessary to isolate nephron segments and developed a novel 3D in vitro system that employs mouse kidney tubule fragments containing endogenous progenitor cells to yield a collecting duct‐like (Dolichos biflorus agglutinin, DBA+) phenotype. After initial seeding of tubule fragments from postnatal mouse kidneys in Matrigel, a subset of healthy cells displayed strong expression of the renal stem cell and mesenchymal mesoderm (MM) marker, Six2. Six2 progenitor cells during kidney development secrete the growth factor glial derived neurotrophic factor (GDNF), stimulating the elongation and branching of the ureteric bud (UB), eventually becoming the collecting duct system. We harnessed the presence of the Six2 progenitor cells and used a 24 hour pulse of exogenous GDNF to aid in the promotion of UB like cells to promote the growth of collecting duct‐like structures. The GDNF pulse produced a significant increase in the expression of Gata3 and Wnt11 in the resulting tubuloids, without altering the amount of Six2 expression, suggesting preferential growth of collecting duct tubuloids. The addition of a GDNF pulse was augmented with hepatocyte (HGF), epidermal (EGF), and fibroblast (FGF) growth factors, to increase the branching of the growing collecting duct‐like tubuloids, resulting in more differentiated, ciliated structures (E‐cadherin+, ZO‐1+, Na+/K+‐ATPase+, α‐tubulin+) and significantly more tubules as a percentage of total structures. Expanding the applications of this system and using a Pkd2fl/fl Pax8 rtTA TetOCre +mTmG mouse model, we have applied these culture principles to autosomal dominant polycystic kidney disease, where differentiated epithelial structures can be tracked for morphological and organizational changes before and after inactivation of Pkd2 by addition of doxycycline. Therefore, the utility of this new collecting duct‐like culture model is broad and dynamic, providing more insight into culture manipulation of primary mouse cells, in vitro differentiation, and new physiological applications.Support or Funding InformationPKD Foundation, NIDDK (F31 DK117579), and Baltimore PKD Research and Clinical Core Center (P30 DK090868)
Diversity of nasal and intestinal microbiome in the first 24 hours of life in newborns
Authors: Carbajal Patricia Bautista , Pérez-Gopar Martha A. , Espinoza-Torres Bogart , Hernández-Pérez Brenda , Rodríguez-Bernabe Alma A. , García-León Miguel L. , RiveraÁvalos Carlos E. , Santaella-Servin Monserrat , López-soto Iris I. , Ángel-Ambrocio Antonio H. , Wong-Chew Rosa M. 
Published: April 2020

IntroductionDisbyosis in the intestinal microbiome has been associated to disease. It has been described that newborns are sterile and get colonized in the first days. Little is known about the respiratory microbiome in the first hours of life. The aim of the study was to compare the nasal and intestinal microbiome in newborns by c‐section (C) and vaginal delivery (V).MethodsWomen who gave birth in the previous 24 hours were invited to have their babies to participate in the study. Nasal swabs and feces were obtained. DNA extraction from nasal and fecal samples was performed, V3‐V4 of the RNA 16S ribosomal subunit was determined by PCR and NG sequencing of this region was done for taxonomic identification of the microbiome.Results30 C newborns and 30 V were included. There was a 10% detection of V3‐V4 in nasal washes in C compared to 50% in V, and 46% vs 53% detection of V3‐V4 in feces of C and V, respectively. Phylum analysis showed C vs V: Firmicutes in 50% vs 22% Proteobacteria 39% vs 75% Actinobacteria 6% vs 2%, Bacteroidetes 4% vs 0.9%, Verrucomicrobia 0.8% vs 0% and not classified 0.6% vs 0.2%, respectively. In nasal samples C vs V we found: Firmicutes 49% vs 45%, Proteobacteria 36% vs 27%, Actinobacteria 4.4% vs 11%, Bacteroidetes 7.6% vs 10%, Fusobacteria 0.2 vs 3% and not classified 2.8% vs 4%, respectively.The genus analysis showed in C newborns feces: Enterococcus in 20%, Streptococcus 2%, Lactobacillae 1%, Staphylococcus 22%, Clostridiales 2%, Escherichia‐Shigella 22%, Enterobacteriacea 13%, Acinetobacter 1%, Bifidobacterium 4%, Actinomycetales 2%, Bacteroides 2%; in V newborns Enterobacteriacea in 27%, Escherichia Shigella 47%, Clostridiales 18%, Sarcina 1%, Leuconostoc 1%, Bifidobacteria 2%. In nasal samples of V newborns there was a higher genus diversity (30) than C newborns (22) and less Stahylococcus (4% vs 14%) and Streptococcus (11% vs 32%), respectively.ConclusionsA lower proportion of C newborns are colonized in the respiratory airway in the first hours of life. C newborns have Staphylococus and Streptococcus in their intestinal microbiome which can be found in the skin of their mothers while in V newborns Enterobacteria is predominant. A higher genus diversity and less Streptococcus and Staphylococcus is observed in the nasal microbiome of V newborns compared to C newborns.Support or Funding InformationThis study was funded by the Consejo Nacional de Ciencia y Tecnología (CONACYT) Mexico, grant number SALUD 2015‐878, PI Rosa M. Wong‐Chew.
Hypotensive Effects of Ganaxolone are Associated with an Upregulation of GABAA Receptor Subunit Expression in Male Hypertensive Schlager Mice
Authors: Gueguen Cindy , Le-Pham Phuong-Nhan , Jackson Kristy L. , Paterson Madeleine R. , Esler Murray , Marques Francine Z. , Lambert Elisabeth , Head Geoffrey A. 
Published: April 2020

Ganaxolone is a synthetic form of allopregnanolone, an allosteric modulator of gamma aminobutyric acid type A receptors (GABAAR). Allopregnanolone reduced blood pressure (BP) in male BPH/2J mice with neurogenic hypertension (Stevenson et al., 2017), which suggests that a lack of tonic inhibition in the forebrain mediates the hypertension. The hypotensive effect of allopregnanolone was associated with an upregulation of the GABAAR a4 and d subunit mRNA in the hypothalamus and medial amygdala of BPH/2J mice. The objective of this study was to investigate the temporal association of the antihypertensive effects of ganaxolone and the alteration in the different GABAAR subunits in the forebrain of BPH/2J mice.12‐week‐old hypertensive BPH/2J and normotensive BPN/3J male mice were implanted with a telemetry probe to record BP and heart rate. Cardiovascular responses to stress tests and pentolinium were measured before and after administering vehicle or ganaxolone (5 mg/kg/day, subcutaneous minipumps) for 2 weeks. The mRNA expression of the GABAAR subunits was measured by real‐time PCR 1 to 2 weeks after the beginning of the treatment in vehicle or ganaxolone‐treated BPH/2J mice.After 2 weeks, ganaxolone reduced BP by 10.7 mmHg (P<0.001) in male BPH/2J mice and reduced the pressor responses during restraint (−8.2 mmHg, P<0.001) and dirty‐cage switch (−12.4 mmHg, P<0.001) stresses compared with pre‐treatment. One‐week treatment with ganaxolone or vehicle had no effect on cardiovascular parameters on either strain. Ganaxolone‐treated BPH/2J mice had increased mRNA expression of α4‐subunit and showed a trend towards increased δ‐subunit of hypothalamic GABAAR compared to vehicle‐treated BPH/2J. None of these effects were seen at 1‐week post‐treatment and in BPN/3J mice.In conclusion, ganaxolone reduced hypertension and the cardiovascular response to stress in male BPH/2J mice but only when upregulated a4 and d subunit mRNA expression of the GABAAR was observed. Therefore, it is likely that the main mechanism of the delayed antihypertensive effects of ganaxolone in neurogenic hypertensive mice is dependent on upregulation of specific GABAAR subunits.
Discovery of small molecules that sensitize Salmonella to polymyxin antibiotics
Authors: Thielen Michaela K. , Carlson Erin E. , May John F. 
Published: April 2020

Salmonella enterica, a major bacterial cause of food‐borne illness, can survive in harsh environments due to its ability to sense and respond to toxic conditions. Salmonella senses a threatening environment, such as antibacterial conditions produced by the body’s immune system, and then activates the expression of genes necessary to survive within that environment. These genes are activated through the use of two component systems. Two component systems consist of an inner membrane‐bound histidine kinase and a response regulator protein located in the cytoplasm of the cell. The PhoP/PhoQ two component system is critical for the virulence of Salmonella and for Salmonella to resist antibiotics such as polymyxin B. Therefore, we tested commercially available small molecules capable of inhibiting the sensory histidine kinase to see if they were capable of sensitizing Salmonella to polymyxin B. Indeed, a few small molecules were successful at sensitizing Salmonella to polymyxin B. To determine how these molecules decrease polymyxin B resistance within Salmonella, we carried out several mechanistic studies. First, we tested whether these small molecules influenced Salmonella’s outer membrane permeability. This was tested by combining small molecules with vancomycin. Vancomycin is an antibiotic used effectively on gram‐positive bacteria that only contain a single membrane, but gram‐negative bacteria are intrinsically resistant to vancomycin due to their outer membrane. We found that vancomycin did not impact Salmonella’s resistance to polymyxin B. These results suggest that the small molecules do not affect outer membrane permeability. We also tested whether these molecules affect expression of PhoP‐activated genes. These molecules have been seen to decrease expression of a PhoP activated gene when transcriptional reporters were used. Using reverse transcription quantitative polymerase chain reaction (RT‐qPCR), we found that the small molecules decreased expression of some, but not all, PhoP‐activated genes. Overall, our results demonstrate that small molecules can target Salmonella’s ability to regulate gene expression and resist toxic conditions. This discovery represents a promising new way to develop antibiotic drugs to treat bacterial infections.Support or Funding InformationThis research was supported by the following funding: UWL Undergraduate Research and Creativity Grants (MKT), UWL College of Science and Health Dean’s Distinguished Fellowship (MKT), Research Corporation for Science Advancement, Cottrell Teacher Scholar Ambassadors for PUI – R1 Partnerships Award (EEC and JFM)