bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Rat Outer Medullary Architecture on Oxygen Distribution
Authors: Edwards Aurelie , Chen Jing , Layton Anita T
Published: June 2021

In this study, we examined the impact of the complex structural organization of the rat outer medulla (OM) on oxygen distribution. We extended a previous region‐based mathematical model of the urine concentrating mechanism in the rat OM to incorporate the transport of red blood cells, hemoglobin, and O2. We considered O2 consumption for basal cellular metabolism and for active transport of NaCl across medullary thick ascending limbs (mTALs). Our model predicts that the OM structural organization results in significant oxygen tension (PO2) gradients both in the axial and the radial directions. The segregation of descending vasa recta, the main supply of O2, at the center and immediate periphery of the vascular bundles gives rise to large radial differences in PO2 between regions and helps preserve O2 delivery to the inner medulla. Assuming that the mTAL active Na+ transport rate decreases when mTAL PO2 falls below a critical level, oxygen availability to mTALs has a significant impact on the concentrating capability of the model OM. The model also predicts that when the OM undergoes hypertrophy, its concentrating capability increases significantly only when anaerobic metabolism supports a substantial fraction of the mTAL active Na+ transport, which is otherwise critically reduced by the low interstitial and mTAL luminal PO2 in a hypertrophied OM.

Support: NIH Grant DK‐53775 (AE and AL) and NSF Grant DMS‐0701412 (AL).
Adenosine Indexes RyR1‐Agonist‐Induced Calcium Overload In Lymphocytes from Malignant Hyperthermia (MH) Susceptible (MHS) Patients
Authors: Bina Saiid , Capacchione John , Muldoon Sheila , Bunger Rolf
Published: June 2021

The RyR1 receptor exists in human blood lymphocytes (B‐cells); RyR1 agonists can induce calcium overload in B‐cells from MHS individuals. We hypothesized that RyR1‐agonism is associated with increased adenosine (ADO) formation due to increased ATP degradation, which is enhanced in B‐cells from MHS subjects.

Method

Venous lymphocyte cells were isolated in HBSS + 1% BSA. Erythro‐9‐(2‐hydroxy‐3‐nonyl) adenine (EHNA, to block ADO deamination) followed by selective RyR1 agonist 4‐chloro‐m‐cresol (4CmC) were added (37 °C for 30 min). HCLO4 terminated reactions. ADO + inosine (INO) were measured by HPLC.

Results

(for 106 cells): ADO + INO levels in control (n=7) and MHS (n=11) cells were 2.7 ± 0.5 and 5.9 ± 0.6 μM respectively. After 5mM 4CmC treatment, ADO + INO increased to 5.6 ± 1.0 and 35.6 ± 3.1 µM in normal vs. MHS cells (P<0.002). There were no overlaps in the ADO+INO levels between stimulated MHS cells and normal cells.

Conclusions

i) RyR1‐agonism‐induced calcium release in B‐cells produces energetic stress that is indexed by increased ADO formation; ii) in MHS cells, 4CmC greatly increases the ADO formation, consistent with increased ATP catabolism due to loss of calcium control; iii) the lymphocyte cells‐adenosine system has clinical potential as a minimally invasive MH diagnostic test.

Supported by USUHS
Modular multiscale model construction, distributed data sources, standards for reproducibility and archiving
Authors: Bassingthwaighte James Bucklin
Published: June 2021

As biological science deepens, integrative models of genetic, cellular and physiological systems enlarge to encompass multiple levels. Ease of understanding diminishes as the complexity increases. Modular construction favors identifiability of elements and allows international collaboration in building and renovating models, given that modules can be readily, preferably automatically, combined. The generic standard for reproducible modeling now needs to be extended more broadly, into standardization of ontologies and of formats for modular code. The archival model forms being developed thus far, like SBML and CellML, and more complex forms that handle spatial features, like JSim, need also to include high quality data sets for validation testing, the sources for the model parameters, and thorough documentation and explanation. This will require new levels of support for the bioinformatics aspects of modern biological research. Since storage and retrieval of anatomic, physiological and pathological data and images is far more complicated than for genomic or proteomic data, and huge archives must be sustained indefinitely, it appears that federal or international sites should be developed. (Supported by NIH T15 HL088516 and HL073598, and NSF 0506477)
The role of calcium‐activated chloride channels to serotonin‐mediated pulmonary arterial tone is influenced by postnatal maturation
Authors: Vemulakonda Srilakshmi , Angermann Jeff , Vranken Kurt , Papamatheakis Demosthenes , Nguyen Dan , Dawson Antoinette , Blood Arlin B , Pearce William J , Longo Lawrence , Wilson Sean M
Published: June 2021

Agonists can induce pulmonary arterial contractility through membrane depolarization and resultant cytosolic Ca2+ increases. The specific mechanism(s) involved in the depolarization process remain controversial, but evidence indicates calcium‐activated chloride channels (ClCa) are pivotal. Our previous investigations show the role of L‐type Ca2+ channels is depressed in fetus relative to adult, and thus we were interested in testing the hypothesis that the role for ClCa changes in parallel. This hypothesis was assessed by wire‐myography of isolated pulmonary arteries from fetus and adult, and confocal imaging of Ca2+ in fluo‐4 loaded arteries. Pulmonary arterial constriction to 10 μM serotonin (5‐HT) in adult was substantially inhibited by the ClCa blocker niflumic acid (NFA; 100 μM). In comparison, NFA did not reduce tension in 5‐HT contracted pulmonary arteries from fetus or 15 day‐old lambs. Confocal microscopy of fetal pulmonary arteries showed NFA also failed to reduce Ca2+‐dependent signaling, which we presume to be the mechanism underlying the ability of NFA to reduce arterial tension. These studies provide the first report indicating developmental progression in ClCa functionality in the pulmonary vasculature. Support from NSF, NIH, UM, and LLUMC.
Metabolomic analysis of plasma in hibernating and active ground squirrels
Authors: Nelson Clark J. , Carey Hannah V.
Published: June 2021

Torpor in hibernating rodents is the most extreme form of hypometabolism in mammals. In order to better characterize this dramatic phenotype at the molecular level, we surveyed plasma metabolites from torpid and aroused 13‐lined ground squirrels during the hibernation season and from fed and fasted spring squirrels using liquid chromatography mass spectrometry. Among the many potential metabolites that are altered by hibernation we validated several related to amino acid, vitamin and lipid metabolism. Multiple long‐chain monocarboxylic fatty acids were elevated in torpid squirrels, which is consistent with the almost complete reliance on stored fat during this time. We also observed elevated levels of long‐chain dicarboxylic acids, which are typically associated with beta‐oxidation through peroxisomal rather than mitochondrial metabolism. The results identify some of the dramatic shifts in circulating metabolites associated with the extreme physiologic changes during mammalian hibernation. Supported by DARPA award W81XWH‐05‐02‐0016.
Functional Studies on Escherichia coli Protein NsrR, a Novel Nitric Oxide Sensitive Transcriptional Repressor
Authors: Bitoun Jacob Philip , Duan Xeuwu , Ding Huangen
Published: June 2021

NsrR, a novel transcriptional repressor from Escherichia coli, coordinates a solvent exposed [2Fe‐2S] cluster through three highly conserved cysteine residues. In the presence of nitric oxide (NO), the iron‐sulfur cluster in NsrR is modified to form a dinitroysl iron complex, and transcriptional repression of NsrR is relieved, promoting the expression of NO detoxifying and defense genes. Here it is shown that NO modification of purified recombinant NsrR occurs at a higher rate than other iron‐sulfur proteins. This result suggests that the NsrR[2Fe‐2S] cluster could be a primary target of NO cytotoxicity. The redox midpoint potential of the NsrR [2Fe‐2S] cluster was determined to be ‐346 ± 7 mV under anaerobic conditions, indicating that in vivo the [2Fe‐2S] in NsrR could be in its reduced state. The mobility shift analysis indicated that the [2Fe‐2S]‐NsrR has a slightly higher binding affinity for its target DNA under reduced conditions than under oxidized conditions, indicating that NsrR may also regulate its transcriptional activity via the redox state of its iron‐sulfur cluster.

This work was supported, in whole or in part, by the National Institute of Health Grant RO1 CA107494 from the United States Public Health Service. This work was also supported by the National Science Foundation Grant MCB‐0416 (to H.D.).
The Effects of Nucleotides on Hexamer Stability of Glutamate Dehydrogenase
Authors: Lekova Virzhiniya , Bell Ellis
Published: June 2021

Bovine glutamate dehydrogenase which catalyzes the oxidative deamination of L‐Glutamate using either NAD or NADP as cofactor, is extensively regulated by a variety of ligands including the purine nucleotides, ADP and GTP as well as having a regulatory site for NADH. The aims of the current study are to establish whether 1] cofactor substrates, and 2] purine nucleotide regulatory ligands affect the stability of the hexamer. Guanidine Hydrochloride denaturation‐renaturation experiments were performed using the fluorescence of the three tryptophans in each subunit. Fluorescence emission spectra and lifetime measurements were used to follow the effects of denaturation and the impact that added ligands have. Dilution experiments were used to indicate whether the presence of ligands affected refolding of the protein. The results demonstrate that both cofactors and purine nucleotides affect both unfolding and refolding processes. Interestingly in the denaturation steps NADPH which binds only to the active site has similar effects to NADH which binds to both active and regulatory sites.

Supported by NSF Grant MCB 0448905 to EB
Protein flexural dysfunction: Loss of structural rigidity in a Hsp40 J‐domain mutant correlates with loss of Hsp70 activation
Authors: Landry Samuel J. , Bascos Neil Andrew
Published: June 2021

Functions of the Hsp40/DnaJ ‐ Hsp70/DnaK chaperone machine involve cyclic conformational changes in DnaK that are coupled to ATP hydrolysis in the ATPase domain of DnaK and stimulated by the J‐domain of DnaJ. Experiments with recombinant forms of the DnaJ J‐domain (Jd) and the DnaK ATPase domain (Kase) reveal that a Jd mutant with a D‐to‐N substitution in the conserved HPD tripeptide (JdD35N), has increased affinity for Kase but is unable to stimulate ATP hydrolysis in DnaK. NMR studies on Jd and JdD35N revealed increased bending of Helix II in JdD35N upon binding to Kase. We hypothesize that J‐domain structural rigidity is essential for its stimulation of ATP hydrolysis. Jd conformational strain was measured by 15N‐1H chemical shift perturbations in heteronuclear single quantum correlation (HSQC) NMR spectra, and Jd‐Kase affinity was modulated by potassium ion concentration. Jd conformational strain increased at higher binding affinity when a mutation in Kase prevented its own conformational change. Comparison of the slopes of integrated chemical shift perturbation versus ΔGb for Jd and JdD35N bound to the Kase mutant indicate decreased rigidity in JdD35N. Further experiments with ATP‐bound Kase indicate that structural rigidity in the J‐domain is required for stabilizing the ATP‐bound conformation of the DnaK ATPase domain and stimulating DnaK function. This work was supported by NSF grant MCB‐0349578.
Probing the Molecular Basis for Heat Stability and Substrate and Activator Specificity for Thermus thermophilus ADPGlucose Pyrophosphorylase
Authors: Doshi Dhaval , Bhatt Shrey , Harkison Nicul , Matsui Mikiko , Orry Andrew , Meyer Christopher R.
Published: June 2021

ADPGlucose Pyrophosphorylase catalyzes the rate‐limiting step in glucan synthesis. The heat stable T. thermus enzyme is activated by FBP, F6P, and G6P. In order to investigate the molecular basis for heat stability, three unique prolines (P100, 122, 195) have been changed to alanine, and the single and triple mutant proteins purified and characterized. All of the single exhibited reduced Vmax values compared to wild‐type but no significant change in heat stability. The triple mutant had ~30 fold less activity than wild‐type as well as altered apparent affinity for substrates. The wild‐type enzyme was able to utilize CTP, GTP, and UTP in place of ATP to a limited extent, with the alternative nucleotides having Vmax values 15, 3, and 0.1% of wild‐type, respectively. In the presence of UTP, the enzyme displayed higher fold activation. The S0.5 values were increased for these nucleotides as well ranging from a ~20 fold increase for GTP to a 1.5 fold increase for CTP. Molecular modeling indicates involvement of K376 in the allosteric site. In contrast to wild‐type, the K376A enzyme displayed inhibition by the substrate ATP as well as a lower Vmax in the absence of activator. Preliminary data collected at subsaturating ATP concentrations indicates that the altered enzyme has decreased apparent affinity for activators as well as lower fold activation. Supported in part by NSF Grant 0448676.
Role of a Membrane‐activated Structural Switch Mechanism in Chloroplast SRP Receptor Function
Authors: Marty Naomi J , Rajalingam Dakshinamurthy , Kight Alicia D , Lewis Nathaniel E. , Fologea Daniel , Kumar Thallapuranam Krishnaswamy Suresh , Henry Ralph L , Goforth Robyn L
Published: June 2021

Prokaryotic and eukaryotic signal recognition particles (SRPs) differ in the ability of the SRP receptor to partition between an aqueous phase and target membranes during protein targeting. Though membrane binding has been shown to be functionally critical for E. coli SRP receptor function, the regulation of the SRP particle receptor partitioning and the conformation of its membrane‐bound state remain unclear. Our study objective was to identify the critical region responsible for membrane binding in the chloroplast SRP (cpSRP) receptor, cpFtsY. Using recombinant cpFtsY, we have identified a small N‐terminal region responsible for stabilizing a membrane interaction critical to the cpFtsY function in cpSRP‐dependent protein targeting. Functional studies of this region reveal that it is both necessary and sufficient for binding the target membrane. Furthermore, NMR and CD structural studies of this region and a similar region in the E. coli SRP receptor reveal a conformational change in secondary structure that takes place upon lipid binding and correlates with a stimulation of GTP hydrolysis by cpFtsY in the presence of liposomes. These studies suggest a conserved mechanism for both membrane binding and the intramolecular communication that regulates cpSRP receptor functions at the membrane. This research is supported by NIH Grant P20 RR15569 from the COBRE Program of the NCRR and DOE Grant DE‐FG02‐01ER15161.
Functional effects of N‐acetyltransferase 1 (NAT1*10) polymorphisms
Authors: Millner Lori Michele , Barker David F. , Doll Mark A. , States J. Christopher , Hein David W.
Published: June 2021

N‐acetyltransferase 1 (NAT1) catalyzes N‐acetylation of aromatic and heterocyclic amine carcinogens resulting in their activation or inactivation. NAT1*10, a common NAT1 variant in many ethnic groups, is associated with increased risk for numerous cancers and congenital defects. NAT1*10 has putatively been described as a rapid acetylator allele (haplotype) and is characterized by two polymorphisms located in the 3' UTR, one of which disrupts a polyadenylation (polyA) signal. We determined polyA patterns of NAT1*10 compared to referent NAT1*4 using RNase protection assays (RPAs). We employed a novel approach to study functional differences caused by NAT1*10 polymorphisms by using constructs that mimic complete human mRNAs. Plasmid constructs of NAT1*10 and NAT1*4 contained full length human mRNAs including either the NATa (alternative promoter) or NATb (major promoter) 5′‐UTR, the ORF, and 885 base pairs of the 3'UTR region. Following transient transfection into Chinese hamster ovary cells, NAT1‐catalyzed N‐acetylation of p‐aminobenzoic acid was measured by HPLC and NAT1 protein expression was measured by Western blot. mRNA levels were determined by RT‐PCR and polyadenylation patterns by RPA. No differences were observed between NAT1*10 and NAT1*4 in levels of N‐acetyltransferase activity, NAT1 protein and mRNA, or polyA pattern. Supported by USPHS grants CA034627, ES011564, and ES014443 and DOD BC083107.
Gastrointestinal structural and functional responses of piglets to soy based infant formulas with varying isoflavone content as compared to cow milk based formula
Authors: Mathai Rose Ann , Tappenden Kelly A , Kuhlenschmidt Theresa B. , Kuhlenschmidt Mark S. , Donovan Sharon M.
Published: June 2021

Currently, 25% of formula‐fed infants receive soy formulas (SF) that contain isoflavones (ISO), including genistein (GEN). We have shown that GEN added to cow‐milk formula (CMF) reduced intestinal (INT) proliferation in piglets. Herein, the hypothesis that SF differing in ISO content would differentially impact neonatal INT development was tested. Piglets were randomized to CMF, SF (25 mg ISO/L expressed as aglycone equivalents) or a low ISO formula (LSF; 1.1 mg ISO/L expressed as aglycone equivalents). INT samples were collected on day 2, 6, 12 and 21. Daily weight (wt) gain was similar in all groups. SF piglets had looser (p=0.005) stool consistency than LSF and CMF, but all were within a normal range. Intestinal length/kg body wt and jejunal mucosal wt/kg decreased (p<0.0001) over time, but were not affected by diet. Intestinal wt/kg was not affected by day or diet. Jejunal lactase and sucrase activities increased with age, but were unaffected by diet. Ussing Chamber analyses detected no differences in INT electrophysiology (barrier function, glucose and glutamine absorption or chloride secretion). Wt gain, INT growth, enzyme activity and nutrient transport in piglets fed SF or LSF was similar to CMF, suggesting that ISF within SF do not impact INT development. (Funded by Solae LLC and the USDA)
Nutritional Contribution of Lean Beef in Diets of Children (9‐13 Years): National Health and Nutrition Examination Survey, 1999‐2004
Authors: Zanovec Michael , O'Neil Carol E. , Nicklas Theresa A. , Keast Debra R.
Published: June 2021

NHANES, 1999‐2004, 24‐hr dietary recalls were used to examine the contribution of lean beef (LB) to total nutrient intake in diets of children 9‐13 years (n=3,273), and determine dietary intake differences between LB consumers and non‐consumers.. LB was defined by MyPyramid Equivalents Database as beef contributing <9.28g fat per 100g. The nutrient intake from LB in foods was calculated using the FNDDS. Children were classified by tertiles of LB intake. Sample‐weighted means were determined using SUDAAN. Consumption of LB contributed 3.3% to total energy, 3.9% to total fat, 3.0% to saturated fatty acids, and 12.7% to cholesterol intake. LB consumption provided a large percentage of protein (14%), vitamin B12 (21%), and zinc (19%). LB was also an important food source of other nutrients, e.g., niacin (9%), riboflavin (4%), vitamin B6 (9%), iron (6%), phosphorus (6%), potassium (6%), and magnesium (4%). LB provided <1% of total sodium intake. LB contributed positively to diets of consumers, e.g., total dietary intakes of protein, vitamins B6 & B12, zinc, iron, and potassium were higher (p<0.01), compared to non‐consumers for the top tertile of LB intake (mean 4.7 oz/d). Consumption of LB contributes significantly to intake of protein and key nutrients in diets of children. Supported by: National Cattlemen's Beef Association, and USDA.
Consumption of fiber is associated with lower body weight measures in US adults: National Health and Nutrition Examination Survey (NHANES), 1999‐2004.
Authors: Cho Susan S , Nicklas Theresa , O'Neil Carol
Published: June 2021

The objective of this study was to evaluate the effects of consumption of fiber and whole grain (WG) on body weight measures in US adults. A nationally representative sample of U.S. adults participating the NHANES, 1999‐2004, was analyzed for body mass index (BMI) according to quartiles of dietary fiber and WG intake. Participants were divided into four fiber consumption groups: <8.9g/d, 8.9 to <13.63, 13.63 to 19.96, =19.96g/day. Participants were also divided into four WG intake groups: <0.6 (Quartile (Q)1; control), 0.6 to <1.5, 1.5 to <3.0 and =3.0 servings (Q4). Increased consumption of dietary fiber was associated with lower BMI and WC in women and lower WC in men. Increased intake of WG was associated with lower BMI (Q1‐28.52 vs. Q4‐27.78, p<0.05) and WC Q1‐94.0 vs.Q4‐92.23 cm, p<0.05) in women only, but this association disappeared after adjusting for cereal fiber. The data suggest that dietary fiber is an active component in WG effects.

Supported by USDA & Kellogg's Corporate Citizenship Fund.
Arimoclomol® enhances hepatic stress protein accumulation after an acute bout of heat stress
Authors: Bloomer Steven A , Cernak Ibolja , Haak Jodie L , Kregel Kevin C
Published: June 2021

Exposure to extreme environmental conditions can adversely affect homeostasis and lead to serious health consequences. The induction of heat shock proteins (HSPs) in response to stressors maintains cellular and physiological homeostasis. Arimoclomol® (CytRx Corp., Los Angeles, CA) is a co‐inducer of HSP, and while positive effects of Arimoclomol® have been demonstrated in pathological models, less is known about its role in a physiologically relevant stressor such as hyperthermia. The purpose of this study was to evaluate the effects of Arimoclomol® on the accumulation of hepatic HSP after a single bout of heat stress. Male Sprague‐Dawley rats were injected with 200 mg/kg Arimoclomol® (or saline) 1 hour prior to hyperthermia, and at 24‐hour intervals thereafter. HSP expression was assessed via immunoblotting and immunohistochemistry, and we observed a slight increase in HSP27, HSP32 and HSP70 protein levels in the vehicle‐treated groups. Arimoclomol® greatly enhanced accumulation of these HSP, and their levels were maintained for three days after heat stress. This sustainment of HSP expression with the combination of Arimoclomol® and heat stress demonstrates a novel mechanism of preconditioning that may be useful in preventing heat‐related injury. Supported by the Defense Advanced Research Projects Agency (DARPA), contract number W911NF‐07‐C‐0053.
Alteration in skeletal muscle antioxidant defense gene expression profile following multiple exposures to hyperthermia
Authors: Sanders Sara , Flann Kyle L. , Yamazaki Marie , Baumgard Lance H. , Rhoads Robert P.
Published: June 2021

Heat load is a potent stressor, due in part, to alterations in the production of reactive oxygen species (ROS). The ability of skeletal muscle to mitigate potentially harmful effects of hyperthermia and elevated ROS is unclear. Study objectives were to determine the effects of single and multiple bouts of acute heat stress (HS) on the expression of genes associated with antioxidant defense in soleus (type I; oxidative) and tibialis anterior (TA; type II; glycolytic) skeletal muscles. Male Sprague Dawley rats (n = 12; 9 mo) were randomly assigned to one of 3 treatment groups; thermoneutral (TN; 22°C) or either 1 or 2 exposures to HS conditions (40°C, 20% relative humidity, 6 h each). Rats were anesthetized and skeletal muscles were collected. Total RNA was isolated and cDNA generated for a real‐time PCR‐based array (SABiosciences). During TN, gene expression of antioxidants (catalase, glutathione peroxidases, peroxiredoxins, and superoxide dismutase 1) were greater (p < 0.05) in the soleus compared to TA. After one bout of heat, the difference in antioxidant gene expression observed during TN increased (p < 0.05) further between the soleus and TA. In contrast, differences in antioxidant gene expression between soleus and TA became less apparent following two HS bouts. Overall, this data indicates that HS alters expression of genes associated with antioxidant defense in a skeletal muscle type specific manner.

This work was funded by the National Research Initiative Competitive Grant no. 2008‐35206‐18817 from the USDA Cooperative State Research, Education, and Extension Service.
Inhibition of AMP‐ activated kinase (AMPK) mitigates zinc‐induced inhibition of urate secretion
Authors: Bataille Amy M. , Maffeo Carla , Renfro J. Larry
Published: June 2021

Plasma urate level is primarily regulated by urinary excretion, and ~70% of urate excretion is due to tubular secretion. Birds, which only secrete urate, and humans, which secrete and reabsorb, maintain similar normal urate concentrations (~300 μM). Tubular secretion includes basolateral entry via Oat1/3‐like transport and apical membrane exit via Mrp4 transport, but regulating factors in the pathway remain uncertain. In other systems, cellular stress has been shown to affect transport properties by altering both stress protein levels and transporter expression or activity. We have shown that prolonged zinc‐induced cell stress inhibited active transepithelial urate secretion by chicken renal proximal tubule epithelial cell monolayers (cPTCs) with no change in Mrp4 expression, glucose transport, or transepithelial resistance. Acute exposure of cPTCs to zinc had no effect, nor was there an effect of zinc on urate uptake by isolated brush border membrane vesicles, suggesting involvement of a cellular stress adaptation. AMPK, which responds to cellular stress by shutting down non‐vital ATP‐utilizing processes, may be linked to this stress adaptation. Activation of AMPK by AICAR decreased urate secretion by cPTCs similar to the effect seen with zinc. The AMPK inhibitor, Compound C, prevented both AICAR and zinc inhibition of urate secretion. Supported by NSF.
Lipoprotein lipase (LPL) facilitates the uptake of postprandial vitamin A by the developing tissues
Authors: Wassef Lesley , Quadro Loredana
Published: June 2021

Postprandial vitamin A, incorporated in chylomicrons as retinyl ester (RE), is an important source of retinoids for the developing embryo. Lipoprotein lipase (LPL) hydrolyses chylomicrons to smaller chylomicron remnants‐RE and facilitates the uptake of chylomicron remnants containing retinoids in extrahepatic tissues. Although, its expression has been reported in placenta, it is not clear whether LPL facilitates postprandial uptake of vitamin‐A by this tissue.

In this study, RE levels in embryos from mice lacking placental LPL (MCKhLPL/LPL−/ −) are reduced both on a vitamin‐A sufficient or excess diet, despite a normal embryonic phenotype. Furthermore, when the dams are maintained on a vitamin A‐sufficient diet and their retinoid stores are adequate, pharmacological systemic inhibition of LPL activity, by means of the lipase inhibitor P‐407, impairs the uptake of chylomicrons RE in yolk sac and embryo, but not in placenta. In contrast, when maternal retinoid stores are depleted, pharmacological systemic inhibition of LPL does not impair neither embryonic nor extraembryonic uptake of RE. These results suggest that LPL facilitates the uptake of postprandial vitamin A by the developing tissues, but it is not the only player that ensures availability of dietary vitamin‐A to the embryo.

Research support: NRI Grant no. 2006‐35200‐16580 from the USDA, Bioactive Food Components for Optimal Health Program (31.0)
TIAF1 self‐aggregation is essential for Aβ plaque formation in the human hippocampus
Authors: Chang Nan‐Shan , Chang Jean‐Yun , Lee Ming‐Hui , Lin Sing‐Ru
Published: June 2021

Role of TIAF1 in the TGF‐β pathway leading to the pathogenesis of Alzheimer's disease (AD) was investigated. We determined that TIAF1 bound Smad4 and blocked its‐regulated promoter activation. TGF‐β1 induced self‐aggregation of transiently overexpressed TIAF1 in a type II TGF‐β receptor (TβRII)‐independent manner. The resulting TIAF1 aggregates upregulated amyloid precursor protein (APP) and superinduced Aβ aggregate formation, which leads to apoptosis essentially in every cell. Smad4 and dominant negative TIAF1 blocked the formation of TIAF1 aggregation. TIAF1 aggregates were found in degenerating and dead neurons, and the interface between metastatic cancer cells and brain cells. By filter retardation assay, TIAF1 aggregates were shown in the hippocampi of postmortem nondemented humans (age 59.3±16.3, n=24), which possessed low levels of Aβ aggregates and Smad4 barely detectable. Co‐presence of TIAF1 with Aβ is 17.7%, but is significantly increased up to 80% in AD patients (age 81.8±9.3, n=60). To reproduce the in vivo observations, neuroblastoma cells were cultured on cancer cell matrices, or co‐cultured with cancer cells, and shown to have induced TIAF1/Aβ aggregates. Together, occurrence of TIAF1 self‐aggregation in the human hippocampus is essential for Aβ plaque formation, indicating a novel mechanism of AD pathogenesis. [supported by NSC and NHRI, Taiwan and DoD, USA]
ATF3 and Intermediate Filament Expression After Optic Nerve Injury (ONI) in Zebrafish
Authors: Cardwell Ayme Suzanne , Mosier Amanda L , Koke Joseph R , García Dana M
Published: June 2021

The role of astrocytes during optic nerve regeneration after ONI in zebrafish is not well characterized. Activating transcription factor 3 (ATF3) is a member of the transcription factor family ATF/CREB, and has been shown upregulated during optic nerve regeneration by Saul et al., 2009 (in press). Previous work by García et al., (2005, Cell Tissue Res., 322(2), 245–56) has shown that astrocytes of zebrafish express cytokeratins rather than the expected GFAP. We examined ATF3 and cytokeratin‐18 expression in the retina and optic nerve by immunofluorescence (IMF) in AB and gfap::GFP zebrafish after ONI. ATF3 expression was elevated in the ONI retina compared to the contralateral retina (CR) after 24 hours. ATF3 expression was significantly elevated in retinal ganglion cell cytoplasm and nuclei and in the cytoplasm and nuclei of cells resembling astrocytes in the optic nerve after 24 and 72 hours. GFP expression was only observed in the Müller glial cells in the retina in both ONI and CR. No GFP expression was observed in any of the optic nerves. Immunolabeling with anti cytokeratin‐18 revealed numerous cells staining positive for cytokeratins in the optic nerve and retina of ONI and uninjured nerves and retinas. This study was supported by NSF grants IOB‐0615762 to DMG and DBI‐0821252 to JRK and DMG.
Mitochondrial function in sparrow pectoralis muscle
Authors: Kuzmiak Sarah , Glancy Brian , Sweazea Karen , Willis Wayne
Published: June 2021

Birds represent an anomaly as they couple a long life span with a high metabolic rate, hyperglycemia, and insulin resistance. Despite the strong links between mitochondria (mito) and aging/longevity, no comprehensive investigation has assessed avian mitochondrial function. Mito were isolated from English sparrow pectoralis and rat mixed hindlimb muscles. Maximal O2 consumption (Jo) and reactive oxygen species (ROS) production were measured in the presence of several oxidative substrates. NAD‐ and FAD‐linked electron transport chain (ETC) capacity was examined in sonicated mito. Compared to rat, sparrow muscle mito oxidize palmitoyl‐l‐carnitine 1.9‐fold faster (211.9 ± 25.6 vs 396.3 ± 36.4 nmol/mg/min), cannot oxidize glycerol‐3‐phosphate, and produce 60% less ROS with complex II linked substrates and both cytosolic‐mitochondrial electron shuttles. Despite similar maximal Jo for the majority of substrates, sonicated sparrow mito oxidize NADH and succinate 3‐ to 5‐fold faster than rat mito, 1809.34 ± 272.05 vs. 647.53 ± 73.07 and 416.93 ± 49.12 vs. 86.83 ± 9.23 nmol/mg/min, respectively. High ETC catalytic potential relative to matrix substrate dehydrogenases in sparrow mito suggests lower matrix redox potential necessary to drive a given O2 consumption rate, which may contribute to the lower ROS production observed in birds compared to mammals. Research supported by a grant from the NSF (IBN‐0116997).
Tissue‐specific activation of AMP‐activated protein kinase by heat stress in the lobster, Homarus americanus
Authors: Podolski Stephanie , Jost Jennifer , Frederich Markus
Published: June 2021

We investigated AMP‐activated protein kinase (AMPK) as a cellular signal during temperature stress in invertebrates. AMPK acts as a “fuel gauge” and since high temperatures lead to an increased energy demand, we hypothesized that AMPK is activated by heat stress in Homarus americanus. Lobsters were exposed to an acute temperature increase (6ºC/h). The temperature induced switch to anaerobic metabolism occurred at 30, 28 or 32ºC in heart, liver or muscle, respectively, indicated by significant lactate accumulation. HSP70 levels remained low in all tissues at all temperatures. AMPK activity followed a tissue‐specific pattern: in the heart, a linear increase between 14 and 22ºC, and constant until 32ºC (2.3±0.3 fold), in liver, no change below 26ºC, then a linear increase to 32ºC (1.9±1.1 fold); in muscle, no change between 14 and 32ºC. AMPK mRNA expression also showed a tissue specific pattern: compared to neural tissue AMPK expression at 14ºC was higher in heart (10.2±16.4), liver (1.4±0.8 fold) and muscle (9.3±8.9). These data indicate that in the lobster AMPK is activated by heat stress earlier than HSP70, suggesting that AMPK is a more sensitive indicator of thermal stress. The tissue‐specific differences in AMPK activity and mRNA expression indicate the differential energetic demand of the tissues and the respective role of AMPK during heat stress. Supported by NSF‐0640478 to MF and an APS summer fellowship to SP.
Norepinephrine, through activation of Alpha‐1A ARs, stimulates production of new neurons, leading to an alleviation of depression and anxiety
Authors: Collette Katie , Fagerlie Ruby , Haselton James , Perez Dianne , Doze Van
Published: June 2021

Norepinephrine (NE) is a neurotransmitter which works through activation of adrenergic receptors (ARs). NE has been implicated in neural functions as diverse as neuronal development, emotion, mood, arousal, learning, and memory. A number of antidepressants rely on modulation of NE for their actions, either alone or in concert with other neurotransmitters. NE, through activation of α1AARs, has recently been shown to increase neurogenesis in adult mice. We hypothesize that this may be a mechanism of depression abatement. Due to the unavailability of specific ligands for the α1AAR, we utilized constitutively active mutants (CAMs) engineered to overexpress this receptor (CAM α1AARs). For comparison, we used α1AAR knock out (KO) mice with normal wild type (WT) mice as controls. We assessed the behavior of the mice for depression using the Tail Suspension Test (TST). We also tested for anxiety behaviors using the Marble Burying Test (MBT) and Light Dark Exploration (LDE). We found that CAM α1AAR mice show reduced anxiety and depression when compared to wild type mice, while α1AAR knock‐out (KO) mice did not show significantly different levels of either trait. Future work will determine what types of cells are being created and what their localization, morphology, and physiologic functions are. Funded by: American Physiological Society, University of North Dakota (UND) Ronald E. McNair Postbaccalaureate Achievement Program, North Dakota INBRE Research Experience for UND Undergraduates Program (REFUNDU), NIH and NSF.
Combining Experimental and Mathematical Modeling to Reveal Mechanisms of Macrophage‐Dependent Left Ventricular Remodeling
Authors: Jin Yufang , Han Haichao , Berger Jamie , Dai Qiuxia , Lindsey Merry
Published: June 2021

Progressive remodeling of the left ventricle (LV) following myocardial infarction (MI) can lead to congestive heart failure, but the underlying initiation factors remain poorly defined. The objective of this study, accordingly, was to elucidate the regulatory mechanisms of LV remodeling using integrated computational and experimental approaches. We developed the first mathematical model to study LV remodeling post‐MI by quantifying the dynamic balance between extracellular matrix (ECM) construction and destruction. Our experimental results of post‐MI ECM gene expression and plasma analyte levels in C57/BL6J mice and cardiac fibroblast ECM gene responses to transforming growth factor‐β1 (TGF‐β1) showed that key factors in LV remodeling included macrophages, fibroblasts, TGF‐β1, matrix metalloproteinase‐9, and collagen content. The mathematical model incorporated these key factors and demonstrated that TGF‐β1 stimuli and MMP‐9 interventions with different strengths and interfering time lead to different LV remodeling responses. The predictions fell within the range of experimental measurements for these interventions, providing validation for the model. In conclusion, our results demonstrate that the balance between ECM synthesis and degradation controlled by interactions of specific key factors determine net LV remodeling outcomes. Our mathematical model based on the balance between ECM construction and destruction predicts remodeling outcomes and provides a useful tool to study post‐MI LV regulatory mechanisms.

The authors acknowledge grant support from NSF 0644646, 0602834 (to HH), NIH R01 HL75360 and AHA GIA 0855119F (to MLL), NSF 0649172 and NIH 1SC2 HL101430 (to YJ).
A Conceptual Cellular Interaction Model of Left Ventricular Remodeling: Dynamic Network with Exit‐Entry Evolution Strategy
Authors: Wang Yunji , Han Haichao , Yang Jack , Lindsey Merry , Jin Yufang
Published: June 2021

Progressive remodeling of the left ventricle (LV) following myocardial infarction involves spatial‐temporal interactions among multiple cell types, including myocytes, neutrophils, macrophages, endothelial cells, and fibroblasts. Interactions associated with cellular functional adaption determine cell populations and remodeling outcomes. However, little is known about the relationship among cell populations, interaction strength, and network structure. The objective of this study was to illustrate the effect of cell‐cell interactions on the evolution of cell population in LV remodeling. This research proposed a conceptual cellular interaction model based on a recent established graphic network. Stability analysis was performed to investigate the effects of the interaction strengths on the cellular population in the dynamic network consisting of two cell‐types. Our numerical simulations demonstrated that the interaction strength between two types of cells, number of interaction links, and initial cell population ratio, all together, determine the evolution profiles of the cell population in the network. Our model predicted three potential scenarios of cell population evolution. The results on stability analysis can be used as a useful tool to predict the spatial‐temporal changes of cell populations.

The authors acknowledge grant support from NSF 0644646, 0602834 (to HH), NIH R01 HL75360 and AHA GIA 0855119F (to MLL), NSF 0649172 and NIH 1SC2 HL101430 (to YJ).
Strain array for cell culture: cyclic strain affects epithelial cell spreading
Authors: Simmons Chelsey , Sim Joo Yong , Bächtold Philipp , Pruitt Beth
Published: June 2021

We have designed, fabricated and characterized a strain array (6 mm well plate format) for cell culture that applies different strain to cells plated in each row of wells on the device. This device is capable of applying 0%, 2%, 4%, 7% or 17% strain to distinct samples with separate perfusion paths using a pressure difference of 10kPa. Our device has 25 wells but mimics the geometry of a standard 96‐well plate (for compatibility with automated plate readers and other technologies) and leaves samples easily accessible to assay. Further, samples experiencing different strain fields have separate perfusion pathways. These capabilities are useful in experiments to examine mechanotransduction mechanisms, specifically sensitivity to applied strain. Madin‐Darby Canine Kidney epithelial cells were attached on the device for 3 hrs then cyclically strained at 1Hz. Cells exhibited different patterns of spreading and localization of GFP‐tagged vinculin in response to strain levels over time.

This work is funded by NSF EFRI CBE0735551, NIH R21 HL089027, and CIRM RC1‐00151‐1. CS is funded by the Smittcamp Graduate Fellowship of the Stanford Cardiovascular Institute and an NSF Graduate Research Fellowship.
Trabecular bone structure in the humeral and femoral heads of anthropoid primates
Authors: Ryan Timothy
Published: June 2021

Studies of anthropoid femoral head trabecular bone structure have found broad similarity across taxonomic and locomotor groups. The goal of this study is to assess the effects of differential limb usage on the trabecular bone architecture of the femur and humerus across taxa with diverse locomotor behaviors. High‐resolution computed tomography scans were collected from the proximal humerus and femur of 55 individuals from five anthropoid species including S. syndactylus, Papio sp., P. rubicunda, A. caraya, and P. troglodytes. Trabecular structural features including bone volume fraction, anisotropy, trabecular thickness, and trabecular number were quantified in volumes positioned in the center of each joint. Femoral head bone volume is consistently higher than humeral bone volume in all taxa independent of locomotor behavior. Humeral trabecular bone is more isotropic than femoral trabecular bone in all species sampled, possibly reflecting the emphasis on a mobile shoulder joint and manipulative forelimb. The results indicate broad similarity in bone structure across all anthropoids. Supported by NSF BCS‐0617097.
Functional implications of temporal bone pneumatization in hominids
Authors: Hill Cheryl A.
Published: June 2021

Numerous functions have been proposed for the pneumatized spaces of the skull, ranging from acoustic isolation from self‐generated sounds to pressure equalization around the tympanic membrane. By quantifying pneumatized spaces across a number of species it may be possible to elucidate possible functions based on shared morphology and/or phylogenetic history. The purpose of this study was to compare the morphology of pneumatized portions of the temporal bone in extant hominids to determine possible hypotheses about the functions of those spaces.

High resolution computed tomography scans of the temporal bone were acquired from humans (N=10), chimpanzees (N=10), gorillas (N=10), and bonobos (N=1). Surface areas and volumes of pneumatized spaces were collected from the entire temporal bone using Amira©. Volumes of interest were cropped from the temporal bone using Quant3D software and analyzed for bone volume fractions, trabecular thickness and anisotropy. These measures were compared according to 1) phylogenetic history and 2) shared craniofacial morphology.

Results indicate that the morphology of pneumatized spaces within the hominid temporal bone is not consistently similar or different according to either species membership or shared craniofacial morphology. These findings indicate that the possible functions of pneumatized spaces in the hominid temporal bone are complex and remain elusive.

Research supported by NSF (BCS‐052493) and Leakey Foundation.
Augmented insulin effects on plasma glucose by cranberry procyanidins in streptozotocin‐induced diabetic rats
Authors: Prior Ronald L. , Wilkes Sam , Rogers Theodore J. , Khanal Ramesh , Howard Luke
Published: June 2021

Objectives of this study were to determine if cranberry proanthocyanidins (CPACs) had an antihyperglycemic effect in the presence or absence of insulin in male diabetic Sprague‐Dawley rats. Rats (~250 g)(n=6–10/trt) were given a single intraperitoneal (ip) injection of freshly prepared streptozotocin (STZ) at a dose of 70 mg/kg in 50 mM citrate buffer (pH 4.5). Diabetic animals with hyperglycemia greater than 400 mg/dL on day 7 after STZ injection were used. Treatments included: 1) Oral gavage of tap water; 2) Oral gavage of CPACs in aqueous solution (250 mg/kg body weight); 3) Oral gavage of tap water plus insulin − 9 nmole/animal ip; 4) Oral gavage of CPACs (250 mg/kg body weight) plus insulin − 1.26 nmole/animal ip; 5) Insulin given ip at a dose of 1.26 nmole/animal. Blood samples were collected by tail bleeding, and glucose measured at 0, 30, 60, 90, 120, 150, 210 and 270 min. CPACs did not alter glucose levels compared to water. CPACs plus the low dose of insulin potentiated the insulin effect in lowering glucose equivalent to the high dose of insulin. Area under the curve for blood glucose change following treatment was −22486±6426; − 21219±7322; − 99283±10262; − 89991±4604; − 65605±11463 for treatments 1, 2, 3, 4, and 5 respectively. Cranberry derived procyanidins had an additive antihyperglycemic effect in the presence of a low insulin dose, but not in the absence of insulin. Funded by USDA, ARS and Decas Botanicals.
Obese rat pregnancy impaired fetal development independent of diet and involved the placental WNT pathway
Authors: Strakovsky Rita , Pan Yuan‐Xiang
Published: June 2021

Maternal obesity has been associated with a multitude of maternal morbidities, and epidemiological studies show that children of obese mothers are at higher risk for obesity, diabetes, hypertension, and heart disease. A healthy diet is the primary recommendation for pregnant women. However, it is unclear whether this prescription will rescue an obese pregnancy. Because the placenta is the primary transport and sensing mechanism between the mother and fetus, this study intends to show that maternal obesity in rat may negatively affect the offspring through the placental WNT pathway regardless of gestational diet. To accomplish this, rats from the Obese Resistant (OR) and Obese Prone (OP) strains were fed the AIN93G (Bal) or a 45% fat (HF) diets throughout pregnancy, and c‐sections were performed on gestational day 21, followed by placental qRT‐PCR analysis. Offspring of OP dams were significantly lighter and had significantly higher blood glucose than OR, with no effect from the HF diet on OP offspring. Placental Axin2, Dkk1, sFRP5 and TNFα, were significantly different in OP animals when compared to OR, but were not affected by the HF diet in OP, and were affected in OR dams. These results suggest that maternal obesity is associated with alterations in the placental WNT pathway as well as fetal physiology, but that a balanced diet in pregnancy may not be enough to prevent the negative fetal outcomes of obese gestation.

Grant Funding Source: USDA
Maternal Low Protein Diet Induces Amino Acid Response (AAR) Pathway in the Liver of Dam Rat
Authors: Wang Huan , Pan Yuan‐xiang
Published: June 2021

Objective

Amino acid response (AAR) pathway reacts to deficiency of dietary protein or an imbalance of essential amino acids. The effects of low protein diet to dam rats during gestation have not been reported. The present study is designed to investigate the impacts of maternal diets on activation of the AAR pathway in dam rats.

Methods

Timed‐pregnant Sprague‐Dawley rats were fed on one of the two isocaloric diets, control (20 kcal% protein, 64 kcal% carbohydrate) or low protein diet (8 kcal% protein, 76 kcal% carbohydrate) during gestation and lactation. The livers of dam rats were collected and used to isolate mRNA and protein.

Results

Low protein diet induces phosphorylation of eIF2alpha and ERK in the liver of dam rats. There were significantly changes in mRNA expression of the downstream target genes in the AAR pathway, such as ASNS (asparagine synthetase), ATF3 (activation transcription factor 3), CHOP(C/EBP homology protein), and SNAT2 (sodium‐coupled neutral amino acid transporter 2).

Conclusion

Maternal high carbohydrate/low‐protein diets fed during gestation and lactation regulates the activation of the AAR pathway in the livers of dam rats.

Grant Funding Source: USDA