bluuebunny/crossref_metadata_2025_split huggingface dataset:
INFLUENCE OF BODY POSITION ON PULMONARY VENTILATION DURING ARREST AND RELEASE OF LOWER LIMB CIRCULATION AFTER EXERCISE IN HEALTHY HUMANS
Authors: da Silva Cesar Tamires , Sayegh Ana Luiza , Oliveira Diogo , Rabelo Mariana , Nery Luiz Eduardo , Taylor Bryan , Silva Bruno 
Published: April 2020

Pulmonary ventilation (V̇E) response to exercise is greater when exercise is performed seated versus supine. Maybe this phenomenon is partially attributed to interaction between neural mechanisms involved on the regulation of V̇E. For instance, venous return is reduced during seated exercise, which activates the cardiopulmonary baroreflex. Therefore we sought to investigate if the cardiopulmonary baroreflex interacts with the muscle metaboreflex and the carotid chemoreflex to the regulation of V̇E in healthy humans. Thirteen young healthy subjects participated in the study (7 men). Subjects performed isometric plantar flexion with the dominant limb for 1.5 min in the semi recumbent position. Close to the end of exercise, the circulation of the dominant leg was arrested at the thigh level via cuff inflation. Then, subjects stopped exercising and their position was shifted from semi‐recumbent to either: 1) seated with the non‐dominant limb lowered to inhibit the cardiopulmonary baroreflex; or 2) supine with the non‐dominant limb raised to activate the cardiopulmonary baroreflex. Circulatory arrest took 2 min and aimed to trap metabolites into the exercised muscles to sustain muscle metaboreflex activation. Next, the tight cuff was deflated, releasing metabolites from skeletal muscles to the systemic circulation. Another experiment, under free flow recovery, served as unconcluded control. A subset of the subjects (n = 3) have undergone hyperoxia breathing (100% O2) only during release of circulatory arrest at the seated position to inhibit the carotid chemoreflex. A normoxic experiment served as control. A rebreathing system was used in an attempt to maintain the end‐tidal partial pressure of CO2 constant throughout all experiments. We found that circulatory arrest did not change V̇E versus unconcluded control in the seated (P > 0.05) and supine (P > 0.05) positions throughout the 120‐s period of cuff inflation. V̇E increased above unconcluded control in the seated position after 60 s of circulatory release (mean ± SD: Δ = 20 ± 29%, P = 0.05) and it remained elevated until the end of data recording at 120 s (Δ = 21 ± 31%, P = 0.04). However, release of circulatory arrest did not change V̇E versus unconcluded control in the supine position (P > 0.05). Furthermore, hyperoxia did not change the V̇E increase after circulatory release at the seated position. Collectively, these results suggest that the cardiopulmonary baroreflex did not interact with either the muscle metaboreflex or the carotid chemoreflex. The underling mechanisms of the V̇E increase during release of circulatory arrest at the seated position deserve further investigation.Support or Funding InformationCAPES and CNPq
CUREing Ocean Plastic Microbes: Positive Experience of Engaging Non‐traditional Undergraduate Students in a Hispanic‐Serving Institution
Authors: Barral Ana Maria , Simmons Rachel E. , Boman-Davis Marie , Bowman Jeff S. 
Published: April 2020

Early participation in research experiences is considered a high‐impact educational practice shown to enhance student engagement in STEM. This, in turn, can result in increased enrollment and retention of majors, as well as increased appreciation of science by nonmajors. However, traditional research opportunities such as summer internships are difficult to expand and are often limited to students already invested in STEM. Course‐based undergraduate research experiences (CUREs) broaden the impact of student exposure to research by making it a required part of a course.We report the result of the integration of a CURE addressing microbial colonization of plastic in coastal Pacific waters in both non‐majors and major’s biology courses during a one‐year period. This CURE, a collaboration between a large private non‐profit university serving nontraditional students and a world‐renowned research‐oriented institution, received NSF funding in 2018 (NSF‐HSI #1832545).The CURE incorporates an existing research project, which explores the nature of microbial populations colonizing different types of plastic using metagenomic sequencing and traditional microbiology techniques. Students participate in field and laboratory research, and interact with research scientists and graduate students. Course level assessment involve surveys and focus groups to evaluate student engagement. Institutional assessment is planned to monitor biology degree retention.As of November 2019, students from four non‐majors and 2 majors’ courses (one lower and one upper division) have participated in the CURE. Students were asked fifteen questions related to knowledge of different aspects of the course, laboratory skills, plastic research, and appreciation of scientific research results. The questions were framed in an after/before format which allowed for a two‐tailed t‐test (alpha = 0.05) in the one‐group posttest only design. Results showed statistically significantly differences in all questions indicating improvements across all assessed areas (n=49). Student open‐ended comments about the experience were overwhelmingly positive. Future plans include assessing BS Biology majors’ retention using a longitudinal cohort model, and expanding nonmajors’ participation in the CURE to promote enrollment in the major.Due to the modular nature of the CURE, its framework can easily be adopted and modified to other courses and curricula. We anticipate that this CURE could be a widely applicable model for biology and ocean science education and disseminated to institutions serving nontraditional adults.Support or Funding InformationThis work has been supported by NU internal grants, as well as the NSF HSI’s new to NSF award #1832545
Biventricular Shape Modes Associated with Clinical History and Pulmonary Regurgitation in Repaired Tetralogy of Fallot
Authors: Govil Sachin , Mauger Charlene , Hegde Sanjeet , Perry James , Suinesiaputra Avan , Omens Jeff , McCulloch Andrew , Young Alistair 
Published: April 2020

Surgical repair of tetralogy of Fallot (ToF) often involves damage to the right ventricular (RV) outflow tract typically resulting in pulmonary valve impairment and subsequent pulmonary regurgitation. Residual pulmonary regurgitation leads to progressive RV remodeling in the form of RV dilation and apical bulging, and plays an important role in long‐term outcomes. Patients with severe pulmonary regurgitation and RV decompensation undergo pulmonary valve replacement (PVR) to reduce the risk of arrhythmia, heart failure, and sudden death. However, the clinical decision on whether and when to perform PVR remains unclear. We sought to quantify biventricular shape modes associated with clinical history and pulmonary regurgitation prior to valve replacement using a biventricular geometric atlas constructed using principle component analysis. In this cross‐sectional retrospective study, biventricular shape models were customized using cardiovascular magnetic resonance images from 97 repaired ToF patients. Patients were divided into two groups: those that subsequently had PVR and those that did not. Regression and clustering techniques were used to quantify shape variations associated with type of surgical repair, time following surgical repair, time leading up to valve replacement, and pulmonary regurgitant volumes. Principal components of biventricular shape variation were associated with RV dilation and apical bulging, overall size and sphericity, and valve plane orientation. Biventricular shape modes were quantified using statistical shape modeling techniques and are correlated with clinical history and pulmonary regurgitation.Support or Funding InformationFunding was provided by the National Institutes of Health 1R01HL121754. SG acknowledges National Institutes of Health NHLBI 1T32HL105373. CM acknowledges New Zealand Heart Foundation Grant 1695. AY acknowledges Health Research Council Grant 17/234.
Structural Determination of the CCT:PhLP1:Gβ5 Folding Complex
Authors: Ludlam William Grant , Stewart Michael , Zocca Sean , Shen Peter , Willardson Barry 
Published: April 2020

Before the Gβ subunit of the G‐protein heterotrimer can be assembled into signaling complexes, it must first be folded by the cytosolic chaperonin CCT and by the co‐chaperone Phosducin‐like Protein 1 (PhLP1). PhLP1 has been observed to release the Gβ1 isoform from CCT after folding. In contrast, PhLP1 increases the affinity of the Gβ5 isoform for CCT. Here we present a structure of CCT in complex with PhLP1 and Gβ5 at less than 4 angstrom resolution. Using a combination of cryo‐electron microscopy and crosslinking coupled with mass spectrometry, we found this structure differs markedly from the previously published complex of CCT with PhLP1 and Gβ1. In the case of Gβ5, the substrate sits deep in the CCT folding chamber between the CCT rings, whereas Gβ1 sits high in the folding chamber associated with the apical domain of the CCT3 subunit. The position of PhLP1 is also distinct, presumably to accommodate the differences in substrate position. These structural observations provide insight into the different roles PhLP1 plays in folding Gβ1 and Gβ5 and their subsequent dimerization with Gγ subunits or RGS proteins, respectively.Support or Funding InformationR01‐EY012287
Characterization of Pancreatic Cancer‐Targeting Peptides MCA1 and MCA2
Authors: Asar Mallika , Soendergaard Mette 
Published: April 2020

Pancreatic cancer is the fourth leading cause of cancer deaths in the U.S., characterized by a 5‐year survival rate of 3%. The dire prognosis is due to inadequate detection methods. However, peptides offer advantages regarding in vivo molecular targeting due to their small size and ample binding affinity. Thus, peptides may be used in imaging of pancreatic cancer for the detection of the disease.Bacteriophage (phage) display technology using a 15‐mer fUSE5 peptide library (1013 virions) was previously performed by an initial negative selection round against 106 normal human pancreatic (hTERT‐HPNE) cells. Unbound phage were amplified in E. coli K91BK and isolated using PEG/NaCl precipitation. Phage (1013 virions) were then subjected to four subsequent rounds of positive selection against 106 human pancreatic cancer (Mia Paca‐2) cells. Following the last round, amplicons were produced by PCR and submitted to next‐generation sequencing. The results identified two clones, pMCA1 and pMCA2, which were comparatively prevalent in the fourth positive round.In order to evaluate the pancreatic cancer binding properties of phage‐displayed peptides (MCA1 and MCA2), the ligands were synthesized with an N‐terminal GSG spacer and a biotin group. A modified ELISA and fluorescent microscopy were performed, in which 10 μM MCA1, MCA2, J18 (negative control), or DMSO (vehicle) was incubated with Mia Paca‐2, hTERT‐HPNE, ovarian adenocarcinoma SKOV‐3, prostate cancer LNCaP, or immortalized human embryonic kidney HEK 293 cells for 1 h. For the modified ELISA, bound peptides were probed by HRP‐conjugated streptavidin, and detected spectrophotometrically at 405 nm after the addition of ABTS. For fluorescent microscopy, bound peptides were detected by FITC‐conjugated streptavidin. Results showed that MCA1 and MCA2 exhibited significantly (p<0.01) higher binding to Mia Paca‐2 cells, compared to J18 and DMSO, while no binding was detected to hTERT‐HPNE, SKOV‐3, LNCaP, or HEK 293 cells. Fluorescent microscopy validated these results by showing significantly (p<0.0001) increased fluorescent intensity of MCA1 and MCA2 to Mia Paca‐2. However, only minimal fluorescent intensity was observed to hTERT‐HPNE, SKOV‐3, LNCaP, or HEK 293 cells. This study indicates that peptides MCA1 and MCA2 specifically target pancreatic cancer cells. Hence, these ligands may be utilized in further studies to improve the detection of pancreatic cancer.
Tcf19 Knockout Mouse Islets Have Increased Stress‐related Gene Expression and Reduced Proliferative Capacity
Authors: Blumer Joseph T. , Han Jee Young , Yang Grace H. , Lodh Sukanya , Fontaine Danielle A. , Davis Dawn B. 
Published: April 2020

Transcription factor 19 (Tcf19) is a putative transcription factor associated with both Type 1 and Type 2 diabetes. Tcf19 is expressed in human and rodent pancreatic β‐cells and is upregulated in proliferating islets and obesity. We generated a whole body knockout (wbKO) of Tcf19 and the resulting lean, 15‐week‐old mice have normal fasting glucose, insulin secretion, and glucose tolerance compared to control. RNASeq led to the identification of 733 upregulated and 763 downregulated genes in wbKO islets compared to control. Overrepresented GO terms include upregulated apoptotic process, and negative regulation of cell proliferation, and downregulated vesicle‐mediated transport. We verified markers of proliferation, β‐cell identity, cell stress, and pro‐apoptosis using RTqPCR. Ki67, Pdx1, Nkx6.1, and Nkx2.2 were significantly decreased while Chop, Bak, Gadd45α, and Dtx3l were significantly increased in islets from wbKO mice. Whole pancreas was harvested to measure β‐cell area and although total area is not different, wbKO mice have altered islet size distribution with an increased number of small islets. Next, β‐cell proliferation and apoptosis were measured in frozen pancreatic sections using Ki67 and TUNEL staining, which revealed significantly less proliferation with no change in apoptosis rates in wbKO mice. In adulthood, β‐cell mass expansion occurs due to proliferation as an early compensation for insulin resistance in response to obesity. To determine the role of Tcf19 in this adaptive response wbKO and control mice were put on a one‐week high fat diet (HFD). After one week on HFD, islets from wbKO do not appropriately upregulate Ki67 and cyclin D2 as measured by RTqPCR. In summary, Tcf19 is involved in proliferation and stress related processes both of which are involved in regulating β‐cell mass, which declines in Type 1 and Type 2 diabetes.Support or Funding InformationVA Merit Award 1I01BX001880VA Merit Award 1I01BX004715TL1 Award TR000429ICTR Clinical and Translational Science Award UL1TR000427NIDDK 5R01DK110324
Timing and Specificity of Cotranslational Nascent Protein Modification in Bacteria
Authors: Yang Chien-I , Hsieh Hao-Hsuan , Shan Shu-ou 
Published: April 2020

Selection of newly‐synthesized proteins into correct protein biogenesis pathways is crucial for cellular homeostasis. The ubiquitous N‐terminal methionine excision (NME) process is mediated by peptide deformylase (PDF) and methionine aminopeptidase (MAP), two essential enzymes in bacteria. This reaction takes place near the nascent peptide exit site of the ribosome, where multiple ribosome‐associating protein biogenesis factors (RPBs) also compete for the access to the nascent chain. How NME achieves its efficiency and specificity at this crowded environment is unknown. Here, using kinetic measurements on purified ribosome‐nascent chain complexes, we show that the ribosome accelerates the MAP reaction for optimal substrates by 102–104 folds. Kinetic competition with translation elongation and selective regulation from other RPBs enhance the specificity of NME by narrowing the processing time window for reactions on suboptimal substrates. With the kinetic data, we constructed a mathematical model and accurately predicted the cotranslational NME efficiency in cytosol. Our data demonstrate how a fundamental enzymatic activity is reshaped by its associated macromolecular environment to optimize both efficiency and selectivity. Moreover, the remodeled MAP activity prompted us to develop a cotranslational assay to screen for MAP inhibitors in the physiological context of translating ribosome. The results explain the discrepancy between traditional peptide‐based assays and cellular data, providing a powerful tool for the development of antibacterial agents targeting the NME machineries.Support or Funding InformationThis work was supported by National Institutes of Health grant GM078024 and a grant from the Weston Havens Foundation to S.‐o. Shan, and a Think Global Education Trust Fellowship from Taiwan to C.‐I. Yang.
Tough Slug Glue: How Transition Metal Binding Proteins Cross‐link an Unusual Bioadhesive
Authors: Christoforo Courtney , Haws Haley , Smith Andrew 
Published: April 2020

In this study, we characterize the role of transition metals in the structure and function of the adhesive secretion of the slug Arion subfuscus. A deeper understanding of this glue’s cross‐linking mechanisms is useful because of its potential to guide the design of novel medical adhesives. We hypothesized that transition metal ions, in particular iron, play an important role in cross‐linking and thus strengthening the glue. We used immobilized metal ion affinity chromatography to identify iron and zinc binding proteins in the glue, and to determine the pH at which these proteins bind and dissociate. Atomic absorption spectroscopy was also used to measure how tightly zinc was bound to the glue at different pH values. The glue was then subjected to tensile tests at pH values where the proteins were bound to metals, and at pH values where they dissociated, to determine if the loss of metal‐binding made the glue weaker. An iron‐binding protein and several zinc‐binding proteins were identified. The zinc was readily removed from the glue as the pH dropped from 6.5 to 4.5, but this had no effect on the glue’s strength. In contrast, the iron‐binding protein stayed bound across a pH range from 3 to 8, but dissociated from iron at a pH of 9. This dissociation appears to impact the glue’s mechanical properties. The precise nature of this effect is still under investigation. These data suggest that iron may be more important to the glue’s strength than zinc. This information should be valuable in guiding the design of synthetic glues that can adhere to wet surfaces, and deform with tissues but maintain toughness.Support or Funding InformationThis work was partially supported by an Ithaca College summer research grant.
Examination of Protein Folding and Metabolic Activity in a Saccharomyces cerevisiae Model for TPI Deficiency
Authors: Hrizo Stacy , Skolnick Kathryn , Schaffold Hailey , Schlosser Lily Jean , Barnes Carol Jean , Koziara Kortnee , Fisher Isaac 
Published: April 2020

Triose Phosphate Isomerase (TPI) is a glycolytic enzyme that catalyzes the inter‐conversion of DHAP to G3P. Mutations in TPI have been identified that are associated with a neurodegenerative disease in humans known as TPI deficiency. To study the cause of TPI deficiency pathogenesis, we constructed Saccharomyces cerevisiae yeast strains expressing six different TPI alleles that are associated with the development of TPI deficiency in humans and Drosophila melanogaster. Interestingly, not all of the TPI alleles exhibit similar characteristics in terms of stability, temperature sensitivity and activity. Yeast with the M80T allele exhibits significant changes in growth and metabolic activity at all temperatures. Yeast with the E104D allele exhibit an acute temperature sensitive phenotype for growth and metabolic activity at 37C. All of the alleles except C41Y demonstrate protein instability at 37C. This study further examines the role of protein folding in TPI deficiency disease pathogenesis. Yeast expressing the mutant TPI alleles were examined for activation of HSF, a cytoplasmic protein folding stress response transcription factor. Understanding the activation of cell stress pathways in TPI deficient yeast may lead to understanding of disease pathogenesis in TPI deficiency patients and provide potential pharmacological targets.Support or Funding InformationFaculty Research Development Grant from Slippery Rock University
Role of AIG1 and ADTRP in Endogenous FAHFA Regulation
Authors: Ertunc Meric Erikci , Kok Bernard P. , Parsons William H. , Wang Justin G. , Tan Dan , Donaldson Cynthia J. , Pinto Antonio M. , Vaughan Joan M. , Ngo Nhi , Lum Kenneth M. , Henry Cassandra L. , Coppola Aundrea R. , Niphakis Micah J. , Cravatt Benjamin F. , Saez Enrique , Saghatelian Alan 
Published: April 2020

Androgen‐induced gene 1 (AIG1) and Androgen‐dependent TFPI‐regulating protein (ADTRP) are atypical transmembrane hydrolases that rely on a catalytic threonine for their enzymatic activity. In vitro characterization of AIG1 and ADTRP in lysates and cells identified fatty acid ester of hydroxy fatty acids (FAHFAs) as their putative substrates. Here, we generate ADTRP knockout (Adtrp‐KO), AIG1 knockout (Aig1‐KO), and ADTRP/AIG1 double deficient (DKO) mice using CRISPR‐Cas9 technology to test whether these enzymes regulate FAHFAs in vivo. AIG1, ADTRP, or a deficiency in both enzymes leads to decreased FAHFA hydrolytic activity in tissue lysates. Quantitative measurement of FAHFA levels in several tissues revealed increased FAHFA levels in brown adipose tissue (BAT), subcutaneous adipose tissue (SQWAT), and perigonadal WAT (PGWAT) of Adtrp‐KO mice consistent with the loss of FAHFA degrading activity. Furthermore, contribution by AIG1 was modest and only observed in the kidney and BAT of DKO mice. Lipidomics of tissues from knockout and wild type control mice detected no significant changes in other lipid classes to indicate that these enzymes are specific for FAHFA substrates. Furthermore, we developed a potent and selective, dual AIG1/ADTRP inhibitor to enable pharmacological interrogation of these enzymes in vivo. Chemical inhibition of AIG1 and ADTRP raised FAHFA levels demonstrating acute regulation of FAHFAs. In aggregate, the results establish AIG1 and ADTRP as the only endogenous FAHFA hydrolases known, and describe resources (mice, inhibitors) needed to elucidate the biochemical and physiological role of these exciting enzymes.Support or Funding InformationThis research was supported by the NIH (DK106210, DK114785, DA033760), The Leona M. and Harry B. Helmsley Charitable Trust (grant #2012‐PG‐MED002 to A.S.), NCI Cancer Center Support Grant P30 (CA014195 MASS core, A.S.), Dr. Frederick Paulsen Chair/Ferring Pharmaceuticals (A.S.), a NIH F32 postdoctoral fellowship, DK111159 (M.EE.), a Hewitt Foundation for Medical Research Fellowship (W.H.P.), Mass Spectrometry Core of the Salk Institute with funding from NIH‐NCI CCSG: P30 014195, NIH 1S10OD021815‐01 and the Helmsley Center for Genomic Medicine, and Transgenic Core Facility of the Salk Institute with funding from NIH‐NCI CCSG: P30 014195.