bluuebunny/crossref_metadata_2025_split huggingface dataset:
Progression of Chemoreflex (Dys−)function in the Streptozotocin‐Induced Rat Model for Alzheimer’s Disease
Authors: Thapa Mahima , Trivedi Mansi , Ostrowski Tim Daniel 
Published: April 2020

Alzheimer’s disease (AD) is associated with gradual memory decline and impairment of cognitive ability. The majority of AD patients also suffer from multiple apneas during sleep. The sleep‐disordered breathing entails a reduced ability to adjust respiration during low oxygen (hypoxia) and/or increased carbon dioxide (hypercapnia) conditions, indicating dysfunction of the respiratory system.In this study, we measured respiratory responses of the Streptozotocin (STZ) ‐induced rat model of AD to hypoxia (10% O2 ‐ peripheral chemoreflex) and hypercapnia (7% CO2 ‐ central chemoreflex). Measurements were taken at three weeks (early stage) and three months (late stage) following STZ injection into the lateral ventricles of the brain (2 mg/kg STZ; 6‐week‐old rats, N = 6/group).Three weeks following AD induction, hypoxic exposure increased respiratory rate (RR) of vehicle control (CTL) and STZ‐AD rats. However, this increase was significantly blunted by ~25% in STZ‐AD. The blunted response was partial compensation by increased tidal volume (TV) resulting in a non‐significant decrease of minute ventilation (MV; RR x TV). Three months following AD induction, STZ‐AD rats still had a blunted response of RR to hypoxia, which was similar in magnitude to that observed at 3 weeks. However, at this late time point, baseline RR and MV at normoxia (21% O2) appeared higher in STZ‐AD than those in CTL. Comparing data between time points (3 weeks AD vs. 3 months AD), both groups showed the expected age‐dependent increase in TV and decrease of RR. This decrease in RR was less in STZ‐AD than that in CTL, but the increase in TV was similar in both groups. Thus, STZ‐AD rats had a ~15% higher MV at the 3 months’ time point than at 3 weeks. CTL rats, on the other hand, had similar MV at both ages (~0% change).With exposure to 7% CO2, responses for RR, TV, and MV at 3 weeks were similar between CTL and STZ‐AD rats. Also at 3 months responses did not differ between groups. However, within the STZ‐AD group, MV at 3 months was significantly greater in response to hypercapnia than that at the younger age. This increase was due to the absent age‐dependent drop of RR in STZ‐AD. CTL rats, in contrast, had significantly reduced RR at 3 months, leading to comparable MV at both ages.In summary, major changes were observed in the peripheral chemoreflex of STZ‐AD rats throughout our 3‐months observation period. Both, responses to hypoxia (short‐term) and baseline values of respiration under normoxia (long‐term) were altered in these animals. Central chemoreflex function, on the other hand, remained largely unaltered.Support or Funding InformationConference Travel Scholarship by Truman State University to M Thapa and seed money from A.T. Still University to TDO
The Role of Variable Repetitive Protein Domainsin Azf1p Function and Prion Formation
Authors: Stewart Taylor , Parmenter Mackenzie , Fuchs Stephen M. 
Published: April 2020

Prions are naturally occurring, self‐propagating isoforms of proteins that represent a heritable mechanism for tuning protein function. The yeast transcription factor Azf1p was recently demonstrated to form a prion, [AZF1+], that confers resistance to the drug radicicol but reduces Azf1p target gene expression. Using the Prion‐Like Amino Acid Composition tool, we identified regions of Azf1p that are predicted to contribute to prion formation. Two notable candidates are the polyglutamine (polyQ) and polyasparagine (polyN) domains. Through a bioinformatic analysis of the genomes of 93 lab and wild isolates of S. cerevisiae, we determined that these domains vary in repeat copy number across strains of yeast. The polyQ domain has two alleles, while the polyN domain has six alleles ranging from 17 to 25 N residues. In this work, we are investigating the extent to which the variable polyQ and polyN domains of Azf1p play a role in its transcription factor activity and contribute to [AZF1+] prion formation. This research determines the effects of repeat‐length variation on protein localization and stability, prion activity, and target gene expression.Support or Funding InformationThis work is supported by the Army Research Office (W911NF‐19‐1‐0299)
Effect of senolytic treatment on expression of senescence‐associated miR‐126 expression in young and old female mice.
Authors: Lahde Collin , Nunes Allancer , Cavalcante Marcelo , Saccon Tatiana , Schneider Augusto , Yousefzadeh Matthew , Robbins Paul , Niedernhofer Laura , Kirkland James L. , Tchkonia Tamara , Masternak Michal 
Published: April 2020

Cellular senescence represents one of the major risk factors for chronic liver disease and contributes to morbidity, mortality, and increased healthcare spending. A relevant strategy for understanding the role of senescent cells in liver pathogenesis is to use genetic or pharmacological strategies to eliminate senescent cells. The combination of the senolytic drugs, Dasatinib and Quercetin (D+Q), effectively reduces senescent cell burden in multiple tissues, extending both healthspan and lifespan in mice, and alliviating obesity and age‐associated hepatic steatosis. The aim of this study was to investigate effects of D+Q treatment on livers of young and old female mice. A total of 40 mice, 20 young females (3‐months) and 20 old females (18‐months), was divided into 4 groups: Young (Y) mice treated with either D+Q or placebo and old (O) mice treated with D+Q or placebo. The treatment was performed for 3 consecutive days every 2 weeks over 10 weeks. Comparative analysis of hepatic miRNAs indicated that D+Q treatment significantly decreased levels of senescence‐specific miR‐126 expression in livers of old mice treated with D+Q compared to vehicle‐treated old mice (p=0.025), As expected, there was no effect of D+Q treatment in young animals. Analysis of miR‐126 target genes indicated that PI3K gene expression was significantly increased in response to D+Q treatment (p=0.003). Additionally, Akt1 and mTOR mRNA levels were increased in D+Q‐treated mice (p=0.008 and p=0.02, respectively). In summary, our data suggest that the mechanism of PI3K signaling pathway activation upon elimination of senescent cells by treatment with D+Q is mediated through downregulation of senescence‐specific miR‐126.Support or Funding InformationThis work is supported by National Institutes of Health (NIH) (R56AG061414, R15AG059190 and R03AG059846)
Functional Regulation of Hsp70 Allostery by Post‐Translational Modifications (PTMs)
Authors: Meng Wenli , Clerico Eugenia , Gierasch Lila 
Published: April 2020

The 70‐kDa heat shock proteins (Hsp70s) perform critical functions in the protein homeostasis network, such as assisting nascent chain folding, preventing protein misfolding and aggregation, facilitating assembly of complexes, and driving protein translocation. The function of Hsp70s relies on a conserved allosteric mechanism involving substrate binding and release modulated by ATP binding and hydrolysis, with the participation of co‐chaperones, including J‐proteins and nucleotide exchange factors. Many studies in recent years have demonstrated that post‐translational modifications (PTMs) play important roles in functional regulations of Hsp70s. As an example, a recent report showed that phosphorylation of Hsp70 T495 upon infection by Legionella pneumophila inhibits host protein translation. While the modulation of Hsp70 functions can be achieved by a variety of means, including tuning its allosteric landscape, altering its substrate binding properties, varying its co‐chaperone interaction, etc., the mechanism of functional regulation of Hsp70s through PTMs is still unknown. In the current study, by using nuclear magnetic resonance spectroscopy (NMR) and biophysical/biochemical assays based on phosphorylation‐mimicking mutant, we are able to elucidate the origin of functional regulation by T495 phosphorylation in Hsp70. Phosphorylation of T495 shifts Hsp70 to the conformation favored by ATP binding in which the nucleotide‐binding domain (NBD) and substrate‐binding domain (SBD) are intimately docked, thus reducing the substrate binding activity of the molecular chaperone. These results underline the regulation of Hsp70 function by modulating its allosteric landscape through PTMs.Support or Funding InformationSupported by NIH grant GM118161
A pH Switch Controls Zinc Binding in Tomato Copper‐Zinc Superoxide Dismutase
Authors: Galaleldeen Ahmad , Taylor Alexander B. , Hart P. John 
Published: April 2020

Copper‐zinc superoxide dismutase (SOD1) is a major antioxidant metalloenzyme that protects cells from oxidative damage by superoxide anions (O2−). Structural, biophysical and other characteristics have in the past been compiled for mammalian SOD1s and for the highly homologous fungal and bovine SOD1s. Here, we characterize the biophysical properties of a plant SOD1 from tomato chloroplasts and present several of its crystal structures. The most unusual of these structures is a structure at low pH in which tSOD1 harbors zinc in the copper‐binding site but contains no metal in the zinc‐binding site. The side chain of D83, normally a zinc ligand, adopts an alternate rotameric conformation to form an unusual bidentate hydrogen bond with the side chain of D124, precluding metal binding in the zinc‐binding site. This alternate conformation of D83 appears responsible for the previously observed pH‐dependent loss of zinc from the zinc‐binding site of SOD1. In addition, Analytical ultracentrifugation data suggest that it is a weaker dimer relative to human SOD1.Support or Funding InformationSt. Mary’s Faculty Grant and Biaggini Fellowship
The Pitching Problem: Proxy Measures for the Identification of Pitcher Fatigue
Authors: Aloma Zachary A. , Baller Daniel P. , Hughes David W. , Thomas Diana M. 
Published: April 2020

ObjectiveThis study assessed the utilization of accessible records and metrics in developing proxy measures for fatigue in professional starting pitchers, and to understand the associated effects within lapses in short‐term and long‐term performance.Design and MethodsLeveraging MLB Statcast AI, we pulled relevant data relating to pitches thrown during the 2015 – 2018 regular and postseasons. The available data was then analyzed in three separate iterations to better understand and isolate the impact of critical metrics. This iterative approach isolated the data based on the following subcategories: anecdotal game, seasonal, and aggregate sets.ResultsThrough the prior detailed approach, we established the significance of three unaccounted for workload factors that represented suitable proxies for the identification of fatigue in starting pitchers. These factors included: strike‐to‐ball ratio, rest period, and a hit‐to‐strike ratio. These metrics represent a means of analyzing fatigue in relation to a pitcher’s performance through the course of a single game, and subsequently, inform optimal strategies as to bullpen management.ConclusionsAs a starting pitcher approaches a pitch count of thirty, management staffs can begin to utilize the prior mentioned proxy metrics as indicators of the impact of fatigue on a pitcher’s performance. These measures represent an alternative to traditional methods and an accessible solution.
Bile Acid Composition Contributes to Metabolic Improvements after Sleeve Gastrectomy in Mice
Authors: Tu Jui , Liu Yanjun , Ding Lili , Zhang Eryun , Jin Lihua , Huang Wendong 
Published: April 2020

Obesity and type 2 diabetes (T2D) can be managed by vertical sleeve gastrectomy (VSG), one of the most frequently performed bariatric surgeries. Although VSG can effectively reverse obesity and T2D, the underlying mechanism of how VSG does so is still under investigation. We found that VSG altered bile acid (BA) levels and composition in mice, resulting in gut microbiota change and concomitant metabolic improvements. CYP8B1 is a BA synthesis enzyme in the liver. We found that CYP8B1 was significantly downregulated in mice after VSG. To investigate whether or not CYP8B1 mediates the metabolic effects of VSG, we used Cyp8b1‐deficient mouse model. The results show that although VSG induced weight loss and improvement in glucose tolerance in wildtype mice, VSG barely improved the same parameters in Cyp8b1‐deficient mice. Our study indicates that alterations of BA and microbiota compositions contributes to metabolic improvements after sleeve gastrectomy in mice. CYP8B1 could be one of the mediators downstream of VSG. These results provide novel insight into the roles of bile acids and gut microbiota in VSG, and may help develop gut microbiota‐based therapeutic options to mimic VSG.Support or Funding InformationInternal funding
EVALUATION OF MICRORNA‐155 AS A BIOMARKER OF MALIGNANT PROGRESSION IN PATIENTS WITH GLIOMA DIAGNOSIS
Authors: Cirino Mucio Assis , dos Anjos Caroline , Rodrigues Andressa , Peria Fernanda , Tirapelli Luis Fernando , Junior Carlos Gilberto Carlotti , Tirapelli Daniela 
Published: April 2020

INTRODUCTIONGliomas are neuroepithelial tumors and correspond to approximately 24.6% of all primary brain tumors. In the last decade, great effort has been made in academic circles to characterize gliomas in an attempt to describe clinical behavior, define prognosis and predict therapeutic response. Bioinformatics tools estimate that microRNAs can regulate about 60% of human genes, including a significant number of oncogenes, tumor suppressor genes, and chemo and radioresistance genes. A current problem in clinical practice is the absence of molecular tools to predict the evolution of gliomas classified as low grade, since during postoperative radiological follow‐up these patients may have tumor recurrence with histopathological confirmation of high glioma degree. Tumor transformation in high‐grade glioma has a worsening of prognosis and reduction of therapeutic possibilitiesOBJECTIVESTo evaluate the expression of miR‐124a, miR‐138, miR‐155 and miR‐1275 in human primary and peripheral blood samples from patients diagnosed with low and high grade gliomas (astrocytoma grade I, astrocytoma grade II, astrocytoma grade III, glioblastoma, oligodendroglioma grade II and oligodendroglioma grade III).PATIENTS AND METHODSMicroRNA expression analyzes were performed using the real‐time PCR technique. Sixty‐five adult patients (18–65 years of age) with confirmed histopathological diagnosis of glioma. Considering a level of significance of 5%, the association of categorical qualitative variables and microRNA expression were performed by the Mann‐Whitney test. Survival analysis was performed using the Kaplan‐Meier non‐parametric method.RESULTSThe microRNAs under study did not present hyperexpression in tumor tissue of patients diagnosed with glioblastoma. Only miR‐1275 showed increased expression in patients diagnosed with pilocytic astrocytoma and grade II oligodendroglioma. In addition, tumors of low and high grade oligodendroglial lineage demonstrated overexpression of miR‐1275. In peripheral blood, significant hypoexpression of miR‐1275, miR‐124 and miR‐138 were observed in a glioblastoma sample. There was also a marked hypoexpression of miR‐138 in samples of grade III oligodendroglioma.CONCLUSIONThe microRNAs miR‐124a, miR‐138, miR155 and miR‐1275 did not show hyperexpression in tumor tissue of patients diagnosed with GBM. MiR‐1275 showed increased expression in patients diagnosed with pilocytic astrocytoma and miR‐155 was hyperexpressed only in samples of grade II oligodendroglioma. In addition, tumors of oligodendroglial lineage, of low and high grades, demonstrated hyperexpression of miR‐1275 and miR‐124a. In peripheral blood, significant hypoexpression of miR‐1275, miR‐124 and miR‐138 were observed in the GBM sample as well as marked hypoexpression of miR‐138 in samples of grade III oligodendroglioma.
mTOR Modulates Sodium and Potassium Conduction in Heterologous Expression System
Authors: Shabbir Waheed , Gleason Catherine E. , Saha Bidisha , Leite Dellova Deise C. A. , Pearce David 
Published: April 2020

The role of mammalian target of rapamycin (mTOR) complexes mTORC1 and mTORC2 in ion transport in kidney tubule has been an area of increasing interest in epithelial research. We and others have shown both in cultured cells and in vivo that mTORC2 is the hydrophobic motif kinase for serum and glucocorticoid kinase 1 (SGK1) and that its activity is required for epithelial Na+ channel (ENaC)‐dependent sodium reabsorption in the aldosterone‐sensitive distal nephron (ASDN). However, recent evidence has shown that mTORC2 can also modulate the renal outer medullary K+ channel (ROMK) activity directly. Electrogenic sodium reabsorption through ENaC generates the main driving force in ASDN for potassium secretion through ROMK, and is a key locus of acute regulation of K+ secretion. We suspected that differences observed in various studies may be due to acute vs. chronic regulation. We therefore compared the effects on ENaC and ROMK activity of chronic (through gene‐knockout) and acute (through a pharmacological approach) mTOR inhibition. We used CRISPR‐Cas9 to generate Sin1 (an essential component of mTORC2)‐deficient HEK‐293T cells, which were compared with wild type cells. The cells were transiently transfected with ENaC (alpha, beta gamma subunits) and ROMK1 channels. After recovery, the cells were treated with either vehicle or the mTOR inhibitor AZD8055 for 30 min and subjected to whole cell patch clamp to assess ENaC and ROMK currents. We found that in Sin1 KO cells (chronic loss of mTORC2) ENaC current was unaffected, while ROMK was markedly reduced. In contrast, acute mTOR inhibition with AZD8055 inhibited ENaC but not ROMK whole cell currents. These data provide initial support for the idea that acute pharmacologic inhibition of mTORC2 and chronic selective inhibition of mTORC2 have opposite effects on ENaC and ROMK activities. However, the results are also consistent with the possibility that global inhibition of mTOR (blocking mTORC1 and mTORC2) has distinct effects from selective inhibition of mTORC2. These observations may provide further insight into such diverse processes as aldosterone escape and the distinct plasma K+ concentrations seen in various types of hypertension.Support or Funding InformationThis work was supported by Relypsa Nephrolgy and Cardiology fellowship 2019–2020 to WS and NIH RO1‐DK 56695 to DP
Craniofacial Morphology of Juvenile Mice with Osteogenesis Imperfecta
Authors: Steele Ashley T. , Organ Jason M. , Menegaz Rachel A. 
Published: April 2020

Osteogenesis imperfecta (OI) is a heritable connective tissue disorder affecting the synthesis and structure of type I collagen (Col1) due to autosomal dominant mutations in proa1(I) or proa2(I) collagen genes (COL1A1 and COL1A2). Clinical manifestations of the severe OI type III include bone fragility, reduced physical stature, low bone mineral density, and midface hypoplasia resulting in a “triangle face” phenotype. To investigate the influence of Col1 on juvenile craniofacial morphology, we used the homozygous OI murine (OIM−/−) mouse model at the weaning stage (21 days).The OIM−/− mouse has a nonlethal recessively inherited mutation of the COL1A2 gene and exhibits adult cranial and post‐cranial phenotypes similar to humans with severe OI type III. OIM−/− and wild type (WT) littermates were weaned at 21 days and scanned in‐vivo with a Skyscan 1176 micro‐CT system. Craniofacial landmarks were collected using 3D Slicer software. Interlandmark distances (ILDs) and centroid sizes were calculated using Past 2.17 software. ILDS were scaled against skull/mandible centroid size to account for the effect of overall body size on shape analyses. Mann‐Whitney U‐tests were used to compare both absolute and relative (scaled) ILDs between the genotypes.Craniomandibular centroid sizes and absolute linear distances (skull, rostrum, palate, and mandible lengths) demonstrate that the OIM−/− mice are smaller overall than their WT littermates. When scaled to centroid size, juvenile OIM−/− mice have a decrease in nasal length, midface height, and mandibular diastema length and an increase in hemimandible length compared to WT mice. For a given skull length, OIM−/− mice have shorter faces in both the anteroposterior and dorsoventral dimensions.The morphometric changes seen in the juvenile OIM−/− mice replicate the “triangle face” that is commonly seen in human pediatric populations with OI. This suggests that this mouse model can potentially be used to investigate the structural changes underlying the human OI phenotype and potential therapeutic interventions. The results of this study can be used to inform future studies of craniofacial developmental in older OIM−/− mice.Support or Funding InformationThis research was supported by an Indiana University Collaborative Research Grant and the Ralph W. and Grace Showalter Trust.
Differing Collagen Responses in the Right and Left Ventricle Following Postnatal Hyperoxia Exposure
Authors: Golding Regina , Braun Rudolf , Kumari Santosh , Goss Kara 
Published: April 2020

BackgroundPreterm birth affects approximately 1 in 10 pregnancies, and extreme preterm birth is associated with a 17‐fold increased risk of heart failure during childhood and early adulthood. Whether this is related to increase cardiac fibrosis is currently unknown. The objective of this study was to determine if fibrosis is present in an animal model of cardiomyopathy of prematurity using postnatal hyperoxia exposure.MethodsPostnatal hyperoxia exposure in an immature rat heart was used to mimic the relative hyperoxia exposure premature infants experience at birth. Timed‐pregnant Sprague Dawley rats (Rattus norvegicus) were allowed to deliver naturally, and pups randomized to either postnatal hyperoxia (85% FIO2) or normoxia (21%) exposure from 0–14 days of life. Dams were rotated daily to prevent maternal oxygen toxicity. On day 21 of life, cardiac tissue was harvested and prepped for Masson’s trichrome blue stain. Additional hearts were resected and the right ventricle (RV) and left ventricle (LV) were flash frozen. The trichrome stained tissue was analyzed using ImageJ to determine the percent of image that was collagen, and colorimetric collagen assays that measured the hydroxyproline were ran on the flash frozen tissue. Results were compared with t‐tests, with p<0.05 used to determine significance.ResultsOverall, presence of cardiac fibrosis was low. In the LV, trichrome analysis demonstrated no difference between the hyperoxic and normoxic groups (4.56x10−4% vs 3.01x10−4 %, p=0.58). Similarly, the collagen assay showed no difference between the hyperoxic and normoxic LV (1.24 ±0.20 μg/g vs 1.01 ±0.34 μg/g, p=0.231). However, in the RV there was decreased percent fibrosis in hyperoxia relative to normoxia (2.69x10‐3 % vs 4.88x10‐3 %, p=0.03). The collagen assay showed similar results of a trend towards decreased collagen in hyperoxic RV compared to the normoxic RV (2.01±0.45μg/g vs 2.57±0.27μg/g, p =0.09).ConclusionThese results appear to suggest that cardiac fibrosis is not a prominent feature in the animal model of cardiomyopathy of prematurity. Whether this is true for humans born preterm merits further study in the function and structure of the human heart throughout its development. The increased risk of heart failure could be caused by factors other than collagen deposition, or collagen deposition that occurs later in life. Further testing is required to fully understand the relationship between hyperoxygenation and long‐term heart health.Support or Funding InformationUniversity of Wisconsin Clinical and Translational Science Award program, through the NIH National Center for Advancing Translational Sciences grant NIH UL1TR000427