bluuebunny/crossref_metadata_2025 huggingface dataset:
Multipoint remote and in situ observations of interplanetary coronal mass ejection structures during 2011 and associated geomagnetic storms
Authors: Mishra Wageesh , Dave Kunjal , Srivastava Nandita , Teriaca Luca
Published: June 2021

We present multipoint remote and in situ observations of interplanetary coronal mass ejection (ICME) structures during the year 2011. The selected ICMEs arrived at Earth on 2011 March 11 and 2011 August 6, and led to geomagnetic storms. Around the launch of these CMEs from the Sun, the coronagraphs onboard STEREO-Aand-B and SOHO enabled the CMEs to be imaged from three longitudinally separated viewpoints. We attempt to identify the in situ plasma and magnetic parameters of the ICME structures at multiple locations, for example at both STEREO spacecraft and also at the ACE/Wind spacecraft near the first Sun–Earth Lagrangian point (L1), to investigate the global configuration, interplanetary propagation, arrival times and geomagnetic response of the ICMEs. The near-Earth identified ICMEs of March 11 and August 6 formed as a result of the interaction of two successive CMEs observed in the inner corona on March 7 (for the March 11 ICME) and on August 3–4 (for the August 6 ICME). Our study suggests that the structures associated with interacting CMEs, possibly as a result of deflection or large sizes, may reach to even larger longitudinally separated locations in the heliosphere. Our multipoint in situ analysis shows that the characteristics of the same shock, propagating in a pre-conditioned medium, may be different at different longitudinal locations in the heliosphere. Similarly, multiple cuts through the same ejecta/complex ejecta, formed as a result of CME–CME interaction, are found to have inhomogeneous properties. The study highlights the difficulties in connecting the local observations of an ICME from a single in situ spacecraft to its global structures.
Compilation of selenium metabolite data in selenized yeasts
Authors: LeBlanc Kelly L , Mester Zoltán
Published: June 2021

Selenium-enriched yeast has long been recognized as an important nutritional source of selenium and studies have suggested that supplementation with this material provides chemo-preventative benefits beyond those observed for selenomethionine supplementation, despite the fact that selenomethionine accounts for 60–84% of the total selenium in selenized yeasts. There is much ongoing research into the characterization of the species comprising the remaining 16–40% of the selenium, with nearly 100 unique selenium-containing metabolites identified in aqueous extracts of selenized yeasts (Saccharomyces cerevisiae). Herein, we discuss the analytical approaches involved in the identification and quantification of these metabolites, and present a recently created online database (DOI: 10.4224/40001921) of reported selenium species along with chemical structures and unique mass spectral features.
Thermal Neuromodulation With Focused Ultrasound: Implications for the Technique of Subthreshold Testing
Authors: Sammartino Francesco , Snell John , Eames Matthew , Krishna Vibhor
Published: June 2021

BACKGROUND

During focused ultrasound ablation (FUSA), the presumed stereotactic target is tested with subthreshold sonications before permanent ablation. This testing relies on ultrasound-induced reversible clinical effects (thermal neuromodulation, TN). However, the thermal dose and spot size thresholds to induce TN are not yet defined.

OBJECTIVE

To define the thermal dose and spot size thresholds associated with TN.

METHODS

We performed a retrospective analysis of intraoperative FUSA data of essential tremor patients. Sonications with a thermal dose of less than 25 cumulative equivalent minutes (CEM) were classified as subthreshold. The intraoperative writing samples were independently rated by 2 raters using the clinical rating scale for tremor. The association between thermal dose and tremor scores was statistically analyzed, and the thermal dose and spot size thresholds for TN were computed using leave-one-out cross-validation analysis.

RESULTS

A total of 331 pairs of sonications and writing samples were analyzed; 97 were classified as subthreshold sonications. TN was observed in 23 (24%) subthreshold sonications. The median tremor improvement during TN was 20% (interquartile range = 41.6). The thermal dose threshold for TN was 0.67 CEM (equivalent to 30 s thermal exposure at 43°C). The spot size threshold for TN was 2.46 mm. Ventral intermediate medial nucleus was exposed to TN thermal dose during subablative and ablative sonications.

CONCLUSION

The TN thermal dose and spot size thresholds are significantly higher than the current FUSA standard of care. We recommend long duration (>30 s), subthreshold sonications for intraoperative testing during FUSA. Future investigations should test whether the thermal dose threshold is tissue-specific and determine the mechanisms underlying focused ultrasound TN.
Cow’s milk may be delivering potentially harmful undetected cargoes to humans. Is it time to reconsider dairy recommendations?
Authors: Wehbe Zena , Kreydiyyeh Sawsan
Published: June 2021

Mammalian evolution has shaped milk into a species-specific vehicle for post-natal development, continuing what began within the mother’s womb. Increased consumption of the mother’s breast milk is associated with the most adequate metabolic programming and lowers the incidence of the diseases of civilization during adulthood. An abundance of short sequences of RNA, known as microRNA, exists in mammalian breast milk, enclosed within robust small extracellular vesicles known as exosomes. These microRNAs can epigenetically regulate over 60% of human genes. When cow’s milk is consumed by humans, the bovine exosomes are transported through the gastrointestinal tract, detected intact in the blood stream, and taken up by target cells, where they alter protein expression. The aim of this review was to highlight the role of dairy exosomes and microRNA, and of the type of dairy product consumed, in human diseases. Given that microRNAs are involved in a vast array of physiological processes and associated with several diseases, perhaps caution should be practiced with regard to human consumption of dairy, particularly for individuals within developmentally critical time frames, such as pregnant and lactating mothers, and young children.
Emerging Technologies in Spinal Surgery: Ultra-Low Radiation Imaging Platforms
Authors: Pacult Mark A , Walker Corey T , Godzik Jakub , Turner Jay D , Uribe Juan S
Published: June 2021

BACKGROUND

Spine surgery has seen tremendous growth in the past 2 decades. A variety of safety, practical, and market-driven needs have spurred the development of new imaging technologies as necessary tools for modern-day spine surgery. Although current imaging techniques have proven satisfactory for operative needs, it is well-known that these techniques have negative consequences for operators and patients in terms of radiation risk. Several mitigating techniques have arisen in recent years, ranging from lead protection to radiation-reducing protocols, although each technique has limits. A hitherto-problematic barrier has been the fact that efforts to diminish radiation emission come at the cost of reduced image quality.

OBJECTIVE

To describe new ultra-low radiation imaging modalities that have the potential to drastically reduce radiation risk and minimize unacceptable adverse effects.

METHODS

A literature review was performed of articles and studies that used either of 2 ultra-low radiation imaging modalities, the EOS system (EOS-Imaging S.A., Paris, France) and LessRay (NuVasive, San Diego, CA).

RESULTS

Both ultra-low radiation imaging modalities reduce radiation exposure in the preoperative and perioperative settings. EOS provides 3-dimensional reconstructive capability, and LessRay offers intraoperative tools that facilitate spinal localization and proper visual alignment of the spine.

CONCLUSION

These novel radiation-reducing technologies diminish patient and surgeon exposure, aid the surgeon in preoperative planning, and streamline intraoperative workflow.
Expandable Cage Technology—Transforaminal, Anterior, and Lateral Lumbar Interbody Fusion
Authors: Macki Mohamed , Hamilton Travis , Haddad Yazeed W , Chang Victor
Published: June 2021

This review of the literature will focus on the indications, surgical techniques, and outcomes for expandable transforaminal lumbar interbody fusion (TLIF), anterior lumbar interbody fusion (ALIF), and lateral lumbar interbody fusion (LLIF) operations. The expandable TLIF cage has become a workhorse for common degenerative pathology, whereas expandable ALIF cages carry the promise of greater lordotic correction while evading the diseased posterior elements. Expandable LLIF cages call upon minimally invasive techniques for a retroperitoneal, transpsoas approach to the disc space, obviating the need for an access surgeon and decreasing risk of injury to the critical neurovascular structures. Nuances between expandable and static cages for all 3 TLIF, ALIF, and LLIF operations are discussed in this review.
Global patterns in copepod thermal tolerance
Authors: Sasaki Matthew , Dam Hans G
Published: June 2021

Copepods are key components of aquatic habitats across the globe. Understanding how they respond to warming is important for predicting the effects of climate change on aquatic communities. Lethal thermal limits may play an important role in determining responses to warming. Thermal tolerance can vary over several different spatial and temporal scales, but we still lack a fundamental understanding of what drives the evolution of these patterns in copepods. In this Horizons piece, we provide a synthesis of global patterns in copepod thermal tolerance and potential acclimatory capacities. Copepod thermal tolerance increases with maximum annual temperature. We also find that the effects of phenotypic plasticity on thermal tolerance are negatively related to the magnitude of thermal tolerance, suggesting a potential trade-off between these traits. Our ability to fully describe these patterns is limited, however, by a lack of spatial, temporal and phylogenetic coverage in copepod thermal tolerance data. We indicate several priority areas for future work on copepod thermal tolerance, and accompanying suggestions regarding experimental design and methodology.
A MRG-operated chromatin switch at SOC1 attenuates abiotic stress responses during the floral transition
Authors: Barrero-Gil Javier , Mouriz Alfonso , Piqueras Raquel , Salinas Julio , Jarillo José A. , Piñeiro Manuel
Published: June 2021

Plants react to environmental challenges by integrating external cues with endogenous signals to optimize survival and reproductive success. However, the mechanisms underlying this integration remain obscure. While stress conditions are known to impact plant development, how developmental transitions influence responses to adverse conditions has not been addressed. Here, we reveal a molecular mechanism of stress response attenuation during the onset of flowering in Arabidopsis (Arabidopsis thaliana). We show that Arabidopsis MORF-RELATED GENE (MRG) proteins, components of the NuA4 histone acetyltransferase complex that bind trimethylated-lysine 36 in histone H3 (H3K36me3), function as a chromatin switch on the floral integrator SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) to coordinate flowering initiation with plant responsiveness to hostile environments. MRG proteins are required to activate SOC1 expression during flowering induction by promoting histone H4 acetylation. In turn, SOC1 represses a broad array of genes that mediate abiotic stress responses. We propose that during the transition from vegetative to reproductive growth, the MRG-SOC1 module constitutes a central hub in a mechanism that tunes down stress responses to enhance the reproductive success and plant fitness at the expense of costly efforts for adaptation to challenging environments.
ANALYSIS OF HAND EXPOSURE AMONG NUCLEAR MEDICINE TECHNOLOGISTS IN SAUDI ARABIA
Authors: Alashban Yazeed , Shubayr Nasser
Published: June 2021

The increase in the amount of radioactive materials administered to patients as well as the number of procedures performed has focused attention on the issue of radiation exposure to the hands of workers in nuclear medicine departments worldwide. The study aims to estimate the equivalent doses to the hands of individuals in nuclear medicine departments in Saudi. A cross-sectional analysis was conducted for 404 annual dose records in 16 nuclear medicine departments from 2016 to 2019. The monitoring of individual doses to the hands was performed using a Harshaw ring dosemeters. During the study period, the average annual equivalent doses per handled activity ranged from 0.21 to 0.41 μSv/GBq. The estimated annual activities of radiopharmaceuticals ranged from 2 to 930 MBq per exam. The hand dose averaged over the 4-year study period was determined to be 1.81 ± 0.25 mSv. The collective annual hand dose increased by 265% from 2016 to 2019.
Effect of Tractor Speed and Spray Application Volume on Severity of Scab and Fruit Weight at Different Heights in the Canopy of Tall Pecan Trees
Authors: Bock Clive H. , Wells Lenny , Hotchkiss Michael W.
Published: June 2021

Scab (caused by Venturia effusa) is the most important yield-limiting disease of pecan in the southeastern USA. On susceptible cultivars, the disease is managed using fungicides, but spray coverage is an issue in tall trees. In four experiments, we used an air-blast sprayer to compare scab severity on fruit at 5.0 to 15.0 m height in trees receiving the same dose of fungicide at 468, 935, and 1,871 liter/ha at 2.4 and 3.2 km/h (in two additional experiments fungicides were applied at 4.0 km/h at 470 liter/ha, 4.0 km/h at 940 liter/ha and 4.0 km/h at 1,100 liter/ha). An air-blast sprayer was used for the applications, which included typical recommended active ingredients (a.i.). Nozzles were selected to provide similar proportions of spray to the upper and lower canopy. The treatments (or subsets thereof) were repeated in 2015 to 2017 on cv. Schley and in 2017, 2019, and 2020 on cv. Desirable. All treatments reduced scab compared with the control. Overall, there was no consistent difference among the treatments for severity of scab on foliage, immature fruit, or mature fruit at any height in the canopy up to 15.0 m (maximum height sampled). Fungicide applied at 2.4 or 3.2 km/h at 470 liter/ha was as effective at reducing disease as were the higher volumes (sometimes more so). The scab epidemic severity affected control efficacy. Estimated cost and water savings based on faster speed and lower volume were considerable. These preliminary observations indicate no single volume or speed was consistently superior to control scab; this suggests that, in most seasons, low volumes (higher concentration of a.i.) may be similarly efficacious as high volumes (lower concentration of a.i.) for controlling scab in tall pecan trees and offer greater resource use efficiency.
Efficacy of Hypochlorite in Disinfesting Nonfungal Plant Pathogens in Agricultural and Horticultural Plant Production: A Meta-Analysis
Authors: Copes Warren E. , Ojiambo Peter S.
Published: June 2021

Bleach products containing hypochlorite are commonly used as disinfectants to eliminate nonfungal plant pathogens from production surfaces, tools, plant surfaces, irrigation water, and produce dump tanks. Although bleach products are useful, their effectiveness has been reported to vary under specific settings. A meta-analysis was conducted of 86 studies to assess the overall efficacy of hypochlorite against plant pathogenic bacteria, oomycetes, and viruses and to identify factors that explain differences in product efficacy. Hypochlorite resulted in a significant (P < 0.0001) reduction in disease intensity or propagule viability, with a mean Hedges’ g standardized difference ([Formula: see text]) of 3.01, indicating that overall, hypochlorite treatments are highly effective. However, heterogeneity in g was significant (P < 0.0001) between studies, wherein 69.8% of the variance observed in g was attributed to true effects. Furthermore, an estimate of between-study variability was moderate (τ2 = 1.46). Random effects (REs) metaregression showed limited effects of moderator variables dosage, contact time, targeted material of treatment, and organism type on product efficacy when all organism types were considered together. Because subgroup [Formula: see text] was significantly higher (P = 0.0070) for oomycetes ([Formula: see text] = 3.30) than for bacteria ([Formula: see text] = 2.19), subsequent metaregressions were performed by organism type. For oomycetes, five RE metaregression models, each containing two moderators and their interaction, resulted in significant (P = 0.05) effects, where models with dosage and time, dosage and genus, time and genus, dosage and target, and time and target accounted for ≤50, 71, 57, 48, and 47%, respectively, of the variance in true effect sizes (R2) associated with [Formula: see text]. For viruses, only the RE metaregression model containing time and target and their interaction resulted in significant (P = 0.0435) effects accounting for 38% of the variance in true effect sizes associated with [Formula: see text]. None of the RE metaregression models for bacteria were significant, although they still accounted for ≤28% of the variance in true effect sizes associated with [Formula: see text]. These results show that although the current recommended rates for dosage and contact time for commercial bleach products are generally expected to result in effective disinfestation, the efficacy against nonfungal plant pathogens is expected to be influenced by the organism type and target being treated with hypochlorite.
Genetic Analysis Reveals Relationships Among Populations of Puccinia striiformis f. sp. tritici from the Longnan, Longdong, and Central Shaanxi Regions of China
Authors: Wang Conghao , Li Yuxiang , Wang Baotong , Hu Xiaoping
Published: June 2021

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most important diseases of wheat worldwide. In China, Longnan (LN) and Longdong (LD) in the south and east of Gansu province, respectively, are important P. striiformis f. sp. tritici oversummering areas and are a source of P. striiformis f. sp. tritici inoculum for the major wheat-growing regions in eastern China. Central Shaanxi (CS) is a wheat-growing region that acts as an important bridge zone for stripe rust epidemic development between LN and LD in the west and the Huanghuai wheat-growing region in the east, and thus, it plays an essential role in P. striiformis f. sp. tritici epidemics in China. To study the relationships among P. striiformis f. sp. tritici populations in the three regions (LN, LD, and CS), we sampled 284 isolates from different geographic locations. Based on 10 simple sequence repeat markers, the results demonstrated high genetic diversity in all three regions, although diversity did vary among regions, with LN > LD > CS. Genetic differentiation was lower, with more extensive gene flow between LD and CS. P. striiformis f. sp. tritici populations in the CS region were genetically closer to those from LD than those from LN, which may be a result of geographical proximity and topography. A positive and significant correlation existed between linearized fixation index (FST) and the log of geographical distances among all subpopulations. Linkage disequilibrium analysis showed that subpopulations of P. striiformis f. sp. tritici from Qinzhou, Qincheng, Beidao, and Maiji from LN and Qianyang and Longxian from CS were in equilibrium (P > 0.05), suggesting that somatic hybridization and/or sexual reproduction may exist in these subpopulations.
Synergistic effect of hydrogen sulfide and endotoxin on caveolin‐1 expression in liver sinusoidal endothelial cells
Authors: Larion Sebastian , Culberson Cathy , Norris Eric , Clemens Mark G
Published: June 2021

Hydrogen sulfide (H2S) has been recently shown to be an important gaseous mediator during inflammation. Although H2S has been shown to have acute effects on blood flow in some tissues, its effects on expression of vasoregulatory proteins is not known. Since caveolin‐1(cav‐1) is an important regulator of endothelial nitric oxide synthase activity during endotoxemia, we hypothesized that H2S may contribute to altered vasoregulation during inflammation by modulating the effects of lipopolysaccharide (LPS) on cav‐1 expression. To test this, isolated primary rat liver sinusoidal endothelial cells (rLSECs) were treated with and without lipopolysaccharide (LPS, 100ng/ml) with increasing dosages of H2S (1, 50, 500 μM). H2S at these doses did not affect cell viability as determined by propidium iodide staining. In the absence of LPS, H2S treatment had no significant effect on cav‐1 expression. In contrast, LPS alone induced cav‐1 and this was potentiated by H2S treatment (up to approximately a 2 fold increase over LPS alone) which was significant with 50 μM H2S. These results suggest H2S has a synergistic effect on the LPS‐mediated induction of cav‐1 in rLSEC. This response may contribute to the overall effect of gaseous mediators on dysregulated liver microcirculation during inflammation. Supported by DK38201‐21.
Functional deficits in IL ‐10 and Phosphatidyl Inositol‐3 Kinase (PI3K) contribute to the development of severe colitis.
Authors: Uno Jennifer K , Matsuoka Katsuyoshi , Sheikh Shehzad Z , Elloumi Houda , Li Fengling , Plevy Scott E.
Published: June 2021

Human IBD is a polygenic disorder with genetic modifiers influencing the severity of disease. The IL‐10−/− mouse is an established model for IBD. We previously described mice harboring a mutation in the p110δ subunit of PI3K develop chronic colitis. The phenotype of colitis is mild in IL‐10−/− and PI3K p110δ mutant mice on a C57BL/6 background. Moreover, we describe partial but not complete abrogation of colonic PI3K p110δ expression in germ free IL‐10−/− mice transitioned to SPF housing. Here, we investigate whether a combined genetic defect alters the phenotype of colitis. IL‐10−/− mice were crossed with PI3K p110δ mutant miceto create IL‐10−/−/PI3K p110δ mutant mice. While, 4‐week‐old PI3K p110δ mutant and IL‐10−/− mice display little to no inflammation, IL‐10−/−/PI3K p110δ mutant mice develop severe colitis. 100% of mice developed colitis by 4 months of age, over 50% displayed severe inflammatory changes by 6 weeks and 40% of the mice developed rectal prolapse. Colitis scores from IL‐10−/−/PI3K p110δ mutant mice were significantly higher than age matched PI3K p110δ mutant and IL‐10−/− mice. Colonic explant cultures demonstrated increased levels of IL‐12 p40, p70 and IL‐23 from double deficient mice compared to IL‐10−/− and PI3K p110δ mutant mice (n = 8, p= 0.05). This work highlights the importance of genetic modifiers on disease outcome in IBD and may provide valuable insight into the pathogenesis of human IBD.
Nonlinear phase synchronization changes between SBP and R‐R interval precede syncope in the young
Authors: Ocon Anthony J. , Medow Marvin , Taneja Indu , Stewart Julian M.
Published: June 2021

Nonlinear phase synchronization (PhS) between systolic BP (SBP) and R‐R interval (R‐R) can measure cardiovagal baroreflex. We hypothesized that desynchronization (loss of baroreflex) occurs prior to fainting. 15 fainters (F) and 15 control subjects (C) aged 15–25 underwent 70° head‐up tilt. Hilbert transform followed by bandpass filter (0.005–0.5 Hz) was applied to SBP and R‐R, and phase difference [ΔΦ(t)=(Φ(t)SBP − Φ(t)R‐R)] used to calculate the nonlinear PhS index: PhSI = √(2 + 2). PhSI baseline values were not different between groups. During early tilt, PhSI increased for F and C (F: .22± .04 to .81±.03; C: .23±.04 to .74±.02) followed by a steep decline in F(from .50±.04 to .17±.03), which was absent in C (from .55±0.04 to .37±.05). Directional analysis indicated a small dependence of SBP on R‐R. Approximately 3 min prior to faint, PhSI increased in F (from .17±.03 to .61±.03) that was associated with directional dependence of R‐R on SBP. Wavelet analysis showed coupling and entrainment at the respiratory frequency. Loss of PhS in simple faint is consistent with cardiovagal baroreflex failure.
Aging leads to a loss of cardiac non‐linear dynamics during sleep stages as assessed by statistical irreversibility
Authors: Casali Karina Rabello , Viola Antoine U , Chellappa Sarah Laxhmi , Tobaldini Eleonora , Casali Adenauer Girardi , Porta Alberto , Montano Nicola
Published: June 2021

In physiological conditions heart rate variability (HRV) is mainly mediated through the modulation of sympathetic and vagal neural activities, balancing their relationship around an equilibrium state. Statistical irreversibility (SI) is a fundamental characteristic to evaluate disequilibrium in a dynamical system. Recently, SI studies applied to HRV in physiological and pathological conditions characterized by sympathetic predominance reported significant changes in SI. To test whether SI changes are also present in aging and modified through the sleep‐wake cycle, we applied the multidimensional time irreversibility test (surrogate data approach based on the skewness of the prime variations series) to HR time series obtained by polysomnographic ECG recordings in 12 young (21.1±0.8y) and 12 older (64.9±1.9y) healthy volunteers. In the young group, we found variations across sleep stages with predominance of SI at lower dimensions during wakefulness and at higher dimensions during sleep stages 3 and 4. In older subjects SI changes across sleep were completely lost, the total percentage (low and high dimensions) of SI was attenuated. These results indicate that linear and non linear dynamics in modulating HRV during sleep in young subjects have a distinctive pattern, that is lost with aging. This behaviour could be related to an increased risk for cardiovascular events in older people.
Autonomic control of heart rate by the muscle metaboreflex in humans
Authors: Fisher James P , Seifert Thomas , Hartwich Doreen , Young Colin N , Secher Niels H , Fadel Paul J
Published: June 2021

We sought to examine the autonomic mechanisms of muscle metaboreflex control of heart rate (HR) in humans. In nine male subjects (23±5 yr) graded isolation of the muscle metaboreflex was achieved by post‐exercise ischemia (PEI) following moderate (PEI‐M) and high (PEI‐H) intensity isometric handgrip performed at 25% and 45% maximum voluntary contraction, respectively. Beat‐to‐beat HR and arterial blood pressure (BP) were measured. Trials were performed before and after beta‐adrenergic blockade as well as cardiac vagal blockade. In all conditions, mean BP was increased similarly from rest during PEI‐M, and was further augmented during PEI‐H, indicating graded metaboreflex activation. During PEI‐M under control conditions HR was slightly elevated from rest (Δ3±2 bpm), however this HR elevation was abolished with beta blockade (P<0.05 vs. control) but augmented with vagal blockade (Δ8±3 bpm, P<0.05 vs. control and beta blockade). The HR elevation during PEI‐H under control conditions (Δ9±3 bpm) was greater than with PEI‐M (P<0.05), and was again attenuated with beta blockade (Δ4±2 bpm, P<0.05 vs. control), but was unchanged with vagal blockade (Δ9±2 bpm, P>0.05 vs. control). These findings suggest that isolated muscle metaboreflex activation during PEI in humans elicits a modest sympathetically‐mediated tachycardia that is masked by cardiac parasympathetic reactivation during PEI‐M, but not PEI‐H.
Chronic Tracheal Occlusion Conditioning Modulates Gene Expression in the Medial Thalamus
Authors: Bernhardt Vipa , Hotchkiss Mark , Reyero Vinas Natalia G , Denslow Nancy , Davenport Paul W
Published: June 2021

The thalamus may relay respiratory mechanical information to the cerebral cortex. We hypothesized that respiratory mechanical stimuli will modulate the gene expression profile of the thalamus. Rats were implanted with inflatable tracheal cuffs. Following surgical recovery, they underwent ten days (5 days/week) of transient occlusion conditioning. On day 10, the animals were sacrificed and the brains removed. The medial thalamus was dissected and microarray analysis of gene expression performed. Chronic tracheal obstruction conditioning modulated 4,146 genes (p < 0.05), of which 2,237 were up‐regulated and 1909 down‐regulated. There was a significant downregulation of the glutamic acid decarboxylate genes GAD1 and GAD2 and upregulation of cholecystokinin CCK. The serotonin receptor genes HTR1A and HTR2A were downregulated. Significantly regulated gene ontology categories were learning and/or memory, neurotransmitter synthesis, transport/secretion and inactivation of MAPK activity. The reduced expression of GAD1/2 may lead to decreased GABA levels that would decrease inhibition of CCK. The results suggest that the medial thalamic GABA‐CCK pathway and the serotonin system are modulated by chronic airway obstructions.
Differential regulation of HIF‐1 alpha and VEGF in an anoxia tolerant brain
Authors: Milton Sarah L , Kesaraju Shailaja , Ayyanathan Kasirajan , Prentice Howard
Published: June 2021

We examined vascular endothelial growth factor (VEGF) expression during anoxia and related it to the binding activity and expression of HIF‐1alpha in the anoxia tolerant turtle Trachemys scripta. Whole animals and neuronal cultures were exposed to anoxia and reoxygenation to determine changes in mRNA and protein levels; immunohistochemistry showed VEGF in brain slices while EMSA was performed for HIF binding. High constitutive VEGF transcript and protein levels increased 2‐fold during anoxia, returning to basal upon reoxygenation. Brain slice VEGF‐positive cells also increased following 24h anoxia; VEGF colabelled with NeuN in the cortex while ependymal cells were positive for VEGF only. By contrast, high basal HIF protein levels did not increase in anoxia or reoxygenation, and decreased in whole brain nuclear extracts, as did DNA binding activity. As the results suggested a suppression of HIF in anoxia, we exposed cells to a HIF stimulator, which significantly increased cell death over 4h anoxia. Thus while VEGF is upregulated in this anoxia tolerant model, it is unlikely to be regulated by HIF. As HIF binding in hypoxic conditions promotes many functions known to be actively downregulated in the anoxic turtle, it is not surprising that nuclear levels and HIF binding decrease in this model, to the point where increased HIF activity decreases cell survival. This work was funded by NIH grant R15 S048909–01 to SLM.
Role of endothelium‐derived hyperpolarizing factor (EDHF) in hypoxia‐induced vasodilation in humans
Authors: Leuenberger Urs A. , Spilk Samson , Yoder Jonathan , Blaha Cheryl , Mast Jessica
Published: June 2021

Prior studies suggest that adenosine, nitric oxide and prostaglandins contribute to skeletal muscle vasodilation induced by systemic hypoxia in humans. However, pharmacological blocking studies suggest that other vasodilator systems such as for example endothelium‐derived hyperpolarizing factor (EDHF) may be involved. Fluconazole, an antifungal agent with cytochrome P450 2C9 inhibitor properties can be used to block EDHF. We exposed healthy humans (n=8) to systemic hypoxia (inspired O2 fraction 0.1 for 10 min; arterial pO2 ~38 mmHg) and measured forearm blood flow (FBF, plethysmography) during brachial artery infusion of fluconazole (0.33 mg/min) and of fluconazole and NG–monomethyl‐L‐arginine (L‐NMMA; 50 mg) in the infused and opposite forearms. Forearm vascular conductance (FVC) was calculated as FBF/mean blood pressure. During normoxia, fluconazole had no effect on FVC and failed to attenuate the rise in FVC during hypoxia (P=NS). However, during co‐infusion of fluconazole and L‐NMMA, the hypoxia‐induced increase in FVC was markedly reduced (experimental vs. control: 0.11±0.23 vs. 1.65±0.66 units; P<0.05). Because L‐NMMA induces an experimental NO‐deficient state, these data suggest that EDHF may be uniquely important when bioavailability of NO is diminished. This could have broad implications in conditions characterized by oxidative stress. Supported by NIH P01 HL077670, and M01 RR010732.
Characterization of Ion Channels in Progenitor Cells Isolated From CTEPH Patients
Authors: Firth Amy L. , Platoshyn Oleksandr , Cancino Eric , Yuan Jason X.‐J.
Published: June 2021

The cellular and molecular mechanisms contributing to the pathogenesis of chronic thromboembolic pulmonary hypertension (CTEPH) remain poorly understood. This study characterizes ion channels present in multipotent mesenchymal progenitor cells (MPC) isolated from endarterectomized tissue from patients with CTEPH. A population of myofibroblast‐like cells expressing MPC markers (CD29, CD44, CD73, CD90, CD105, CD166) was identified. These cells formed CUF‐F‐like colonies and were capable of adipogenic, myogenic and osteogenic differentiation. Whole‐cell patch clamp technique was used to isolate K+, Ca2+ and nonselective cation currents (NSCC). Four kinetically different voltage‐dependent K+ currents (Kv) were recorded and inhibited by 4‐AP and TEA. In the absence of extracellular Ca2+, IBTX‐sensitive BKCa currents were detected at membrane potentials >+40mV. Many cells exhibited large NSCC, sensitive to H+ and La3+, but relatively insensitive to 2‐APB and niflumic acid, with a linear current‐voltage relationship reversing at 0 mV. No voltage‐dependent Ca2+ currents were detected. Enhanced expression and oscillatory activity of the Na+‐Ca2+ exchanger (NCX) was observed. The electrophysiological profile of these MPC may suggest a novel pathway for elevation of intracellular Ca2+. Large NSCC may elevate cytosolic Na+, activating the reverse mode NCX to further increase Ca2+ and contribute to remodeling of the pulmonary arteries in CTEPH patients.

Funding source: NIH/NHLBI and CIRM Postdoctoral Fellowship
Differential changes of BNIP3 and beclin‐1 during the right ventricle response to sustained or intermittent hypoxia
Authors: Zhang Jianhua , Joy Anne , Dai Qiuxia , Mifflin Steve , Lindsey Merry L
Published: June 2021

Sustained hypoxia (SH) and intermittent hypoxia (IH) induce remodeling of the right ventricle (RV), but the different models may undertake different cellular and molecular mechanisms during the remodeling process. In particular, apoptosis and autophagy are two important processes that determine cell fate. Accordingly, we hypothesized that SH and IH may differentially regulate levels of BNIP3 (an apoptosis marker) and beclin‐1 (an autophagy marker). Male Sprague‐Dawley rats (125–145 g) were exposed to SH (10% for 7 days; n=6) or IH (21 to 10% oxygen in 6 min cycles for 8 hours per day for 7 days; n=12). Normoxic rats (NM; n=6) were used as controls. Right ventricles were evaluated for BNIP3 and beclin‐1 protein levels by immunoblotting. While SH decreased BNIP3 to 71±22% of NM levels, IH increased BNIP3 to 174±26% of NM levels (both p<0.05). SH did not change beclin‐1 levels, while IH decreased beclin‐1 protein quantity to 44±5% of NM levels (p<0.001). Taken together, our results suggest that apoptosis may be reduced in SH and stimulated in IH, while autophagy may be downregulated in IH. Future studies will examine the functional consequence of these changes as well as evaluate other bcl‐2 protein roles in regulating apoptosis and autophagy in these two hypoxia modes. Supported by NIH (RO1 HL‐75360), AHA (0855119F) to MLL.
Exercise training has protective effects in monocrotaline induced pulmonary hypertension
Authors: Moreira‐Gonçalves Daniel , Henriques‐Coelho Tiago , Fonseca Hélder , Gonçalves Nádia , Ferreira‐Pinto Manuel , Dias‐Neto Marina , Vasques‐Novoa Francisco , Leite‐Moreira Adelino , Duarte José Alberto
Published: June 2021

The use of exercise training as a therapeutic and/or preventive strategy is gaining interest in pulmonary arterial hypertension (PH). We aimed to study the influence of endurance exercise training in monocrotaline (MCT) induced PH. Male Wistar rats were randomly divided according the following groups: i) sedentary with MCT (60 mg/kg sc) or vehicle (SED+MCT and SED+V), ii) 4 week‐exercise training before MCT or vehicle injection (EX+MCT and EX+V) and iii) 4 week‐exercise training after MCT or vehicle injection (MCT+EX and V+MCT). Hemodynamic bi‐ventricular instrumentation with conductance catheters was assessed at 4 weeks after MCT or vehicle injection. After cardiac instrumentation, a morphometric evaluation was performed. In SED+MCT group, MCT induced body and muscular cachexia, RV hypertrophy, RV peak systolic pressure increase, and RV relaxation disturbances. Both groups submitted to exercise training did not develop body or muscular cachexia, presented less RV hypertrophy and no relaxation disturbances. There were no significant differences among groups injected with vehicle. Exercise significantly reduced mortality rate after 4 weeks of MCT injection. We concluded that exercise training seems to have protective effects in MCT model of PH. Supported by FCT: SFRH/BD/33123/2007
Altered bicarbonate‐dependent intracellular pH (pHi) regulation in a cortical collecting duct (CCD) principal cell line from a mouse model of autosomal recessive polycystic kidney disease (ARPKD)
Authors: Liu Xiaofen , Stephens Lauren A. , Olteanu Dragos , Bevensee Mark O.
Published: June 2021

ARPKD in the kidney primarily affects the collecting ducts and leads to tubule dilation, altered cell polarity and morphology, as well as dysfunctional ion transport that promotes Na+ hyperabsorption. Little is known about dysfunctional ion transport associated with pHi regulation. We used fluorescence imaging with the pH‐sensitive dye BCECF to examine the regulation of pHi in a cilium‐deficient (“mutant”) CCD principle cell line derived from a mouse model of ARPKD that lacks the Tg737 gene encoding the ciliary protein Polaris, as well as a cilium‐competent (“rescued”) cell line transfected with Tg737 cDNA. We characterized HCO3−‐dependent pHi regulation following NH4+ prepulse‐induced acid loads by exposing both the apical and basolateral membranes of polarized monolayers simultaneously to 5% CO2/22 mM HCO3– in the presence or absence of 200 μM DIDS, and in the presence of 50 μM HOE‐642 to eliminate Na‐H exchanger activity. As previously reported, HOE‐642 nearly blocked the pHi recovery from an acid load in both cell monolayers bathed in HEPES‐buffered solutions. However, subsequently switching to the HCO3− solution stimulated a pHi recovery that was slower in the mutant vs. rescued cells. During pHi recoveries, total acid extrusion in the pHi range 6.33–7.13 was 29–45% less in the mutant vs. rescued cells; DIDS‐insensitive acid extrusion was similar. DIDS‐sensitive acid extrusion in the pHi range 6.40–6.90 was reduced 37–49% in the mutant vs. rescued cells. Applying DIDS selectively to the basolateral but not apical membrane of rescued cells inhibited the HCO3−‐induced pHi recovery. Reduced HCO3−‐dependent acid extrusion may contribute to Na+ hyperabsorption in this principal cell model of ARPKD. NIH DK067343, NIH T35 HL007473
Influence of [H+] on MPP efflux from CHO cells expressing hMATE1
Authors: Dangprapai Yodying , Wright Stephen H
Published: June 2021

The human multidrug and toxin extrusion protein, hMATE1, is a key transporter mediating organic cation (OC)/hydrogen ion (H+) exchange at the luminal membrane of renal proximal tubule (RPT) cells. Physiologically, hMATE1 secretes OCs from RPT cells into the filtrate. However, kinetic studies of hMATE1 have largely been confined to measurement of OC uptake into hMATE1‐expressing cells. To characterize transport activity of hMATE1 in its native mode, we developed a method to study efflux of 1‐methy‐4‐phenylpyrinidium (MPP) in CHO cells expressing hMATE1. After loading cells with [3H]MPP in pH 8.5 buffer, time course of washout was determined as a function of [H+] in the washout buffer. Efflux involved at least two phases, a fast phase representing ~87% of the accumulated MPP, and a very slow phase that could be subtracted from the first for analysis. Rate constant for MPP efflux of the fast phase (presumably from the cytoplasm) increased significantly (p < 0.0001) when external [H+] was raised from 3.16 nM (pH 8.5; K=0.22 min−1) to 40 nM (pH 7.4; K=0.51 min−1). Half‐maximal MPP efflux occurred at an extracellular [H+] of 4.42 nM (pH 8.35), a concentration not significantly different from the IC50 for inhibition of MPP uptake produced by extracellular [H+] (7.26 nM; pH 8.14). This method offers the promise of measuring the kinetics and selectivity of substrate interaction at the cytoplasmic face of hMATE1. (NIH R56DK080801)
Multidrug And Toxin Extrusion's (MATE) Role in Renal Organic Cation Secretion
Authors: Astorga Bethzaida , Hook Laura L. , Wright Stephen H.
Published: June 2021

The molecular identity of the luminal element of renal organic cation (OC) secretion is suspected to include two novel homologous transport proteins, Multidrug And Toxin Extruders 1 & 2K (MATE1 and MATE2K); they share anticipated characteristics of luminal OC transport, including expression in the apical membrane of human renal proximal tubule (RPT) cells and support of OC/H+ exchange. Here we investigated aspects of the multispecificity of human MATE1 (hMATE1) and MATE2K (hMATE2K). Stable transfection in Chinese Hamster Ovary cells resulted in Kt values for transport of 1‐methyl‐4‐phenylpyridinium (MPP) of 7.6 μM (MATE1) 5.2 μM (MATE2K). Inhibition by tetraethylammonium produced IC50 values of 52 μM and 26 μM for hMATE1 and hMATE2K, respectively. Preliminary data shows that cimetidine is a potent inhibitor of MPP, with IC50s of 1 μM (MATE1) and 3μM (MATE2K). Increasing extracellular H+ concentration cis inhibited hMATE1‐mediated MPP transport with an IC50 value of 15.4 nM (pH of 7.8). Immunohistochemical analysis of paraffin embedded human kidney cortex samples confirmed that hMATE1 and hMATE2K are located in the apical membrane of RPT cells and initial evidence suggests a heterogeneous distribution of both transporters in the cortical RPTs. In conclusion, the selectivities and distribution of MATE1 and MATE2K support the contention that they play a key role in OC secretion in human RPT. (F31DK084769)
Sodium Dicarboxylate Transporters in Placental Cells
Authors: Hering‐Smith Kathleen S , Coleman‐Barnett Joycelynn , Yu Miao , Abdulnour‐Nakhoul Solange , Hamm L Lee
Published: June 2021

Placental cells express a number of transporters of metabolic substrates. To determine the presence and regulation of dicarboxylate transporters, we used an established human placental cell line, JAR. NaDC1 and −3 are respectively low and high affinity dicarboxylate transporters most studied on the apical and basolateral membranes of renal proximal tubule and intestinal cells.

Both NaDC1 and −3 were present in JAR cells by immunohistochemistry and immunobloting; in the latter, patterns and levels were similar to cultured kidney cells. In JAR cells, 14C‐succinate (Succ) uptake averaged 5.1 ± 0.1 pMol/well and increased to 6.3 ± 0.2 (p < 0.05) by lowering Ca2+ to μM levels. Succ uptake was also stimulated (to 6.5 ± 0.2) by exposure to an acid media (pH ~ 7.1) for 48 h; Succ transport after acidosis was not Ca2+ sensitive. 14C‐Citrate (Cit) transport averaged 6.9 ± 0.5 but was not stimulated by either condition. Substrate affinities for Succ and Cit were relatively low, more consistent with NaDC1 than NaDC3.

The stimulation of Succ but not Cit transport by acute reduction in extracellular Ca2+ or prolonged acid media contrasts with prior findings of ours with several kidney cell lines. The complex pattern of regulation suggests the presence of multiple dicarboxylate transporters in these cells with distinct regulation. In conclusion, placental cells contain both NaDC1 and −3, and transport Succ and Cit, but with distinct patterns of regulation. Because Cit complexes Ca2+, regulation of Cit transport could be involved in the placental calcification which occurs late in pregnancy. Funding VA, NIH.
Hypertonicity Increases Urea Permeability through PKC in Inner Medullary Collecting Ducts
Authors: Wang Yanhua , Klein Janet D. , Sands Jeff M.
Published: June 2021

We showed that hypertonicity increases urea permeability as well as UT‐A1 phosphorylation and biotinylation in the inner medullary collect duct (IMCD). We also showed that increases in hypertonicity do not increase cAMP in IMCD, but do increase Ca2+ suggesting involvement of a Ca‐dependent protein kinase in the urea transport response. To further investigate the signaling pathways that might be involved in the response to hypertonicity, we tested the effect of PKC inhibitors on urea permeability in isolated perfused IMCDs. Increasing the osmolality of perfusate and bath from 290 to 690mOsM significantly stimulated urea permeability from 24±2 to 49±4 ×10−5cm/s and was returned to control levels by inhibition of PKC with 10μM chelerythrine or 50μM rottlerin. To determine the potential synergy between AVP and PKC, phorbol dibutyrate (PDBu), was used to stimulate PKC. AVP stimulated urea permeability from 21±2 to 74±16 ×10−5cm/s. PDBu alone did not change the basal urea permeability. In the presence of AVP, however, PDBu significantly increased urea permeability from 74±16 to 94±18 ×10−5cm/s. The AVP and PDBu‐stimulated urea permeability was reduced by 10μM chelerythrine to AVP alone levels. We conclude that hypertonicity stimulates UT‐A1 through a PKC‐mediated phosphorylation. Whether PKC directly phosphorylates UT‐A1 or acts through a cascade remains to be determined. Supported by NIH RO1‐DK41707.
Long term dDAVP increases the expression of urea transporters and ER stress pathway genes in kidneys of mice with urinary concentrating defect.
Authors: Cai Qi , Nelson Sarah , Brooks Heddwen L.
Published: June 2021

It is well‐know that both AQP2 and urea transporter A1 (UTA1) are vasopressin‐regulated genes in normal renal inner medullas. However, we previously reported that 7 day dDAVP regulated AQP2 expression is impaired in the renal inner medulla (IM) of AQP1 null mice with urinary concentrating defect. In the present study, we investigated the regulation of UTA1 and UTA3 in 7day dDAVP infused AQP1 null mice. We found that 7 day dDAVP increases the expression of UTA1 and UTA3 proteins to 212 ± 40.4% vs. control 100 ± 19.5% and 588 ± 93.7% vs. control 100 ± 34.4%, respectively, which are similar to the results from dDAVP infused wild type mice. 7 day dDAVP also increases the expression of endoplasmic reticulum (ER) stress genes in IM of AQP1 null mice. GRP78 mRNA increases by 1.74 fold and protein increases by 2 fold compared to that in control 7 days after dDAVP infusion. Immunohistochemistry demonstrates that 7 day dDAVP causes GRP78 protein localize on the apical membrane of collecting duct cells in the papillary tip of IM with AQP2. Electron microscopy of immuno‐gold staining confirms the apical location of GRP78. Moreover, 7 day dDAVP increases GADD153 mRNA to 2.93 ± 0.13 and ATF4 mRNA to 1.55 ± 0.06 compared to those in controls 1 ± 0.05 and 1 ± 0.06, respectively, in IM of AQP1 null mice. Conclusion: in renal IM of AQP1 null mice 1) the regulation of UTA1 and UTA3 by dDAVP is intact and 2) 7 day dDAVP activates ER stress pathway.