bluuebunny/crossref_metadata_2025 huggingface dataset:
Cation channel TRPC6 activation of TLR4 in endothelial cells mediates sepsis‐induced acute lung injury
Authors: Tauseef Mohammad , Knezevic Nebojsa , Chava Koteswara , Schraufnagel Dean , Smith Monica , Vogel Stephen , Dietrich Alexander , Birnbaumer Lutz , Malik Asrar , Mehta Dolly
Published: June 2021

Loss of lung vascular endothelial cell (EC) barrier integrity and inflammation are main pathogenic features of acute lung injury (ALI). Activation of transient receptor potential canonical channels (TRPC) induces intracellular Ca2+ signaling, which promotes lung vascular permeability. In addition, it is known that LPS binding to TLR4 is crucial in mediating lung inflammation. However, the fundamental question whether TLR4 and Ca2+ signaling converge to induce lung vascular leakiness and inflammation is unknown. Here we show that deficiency of the TRPC6 isoform prevented TLR4‐mediated signaling in endothelial cells rendering Trpc6−/− mice resistant to endotoxin‐ and sepsis‐induced lung injury. We observed that LPS‐mediated diacylglycerol generation was responsible for inducing TRPC6 activity which in turn activated non‐muscle myosin light chain kinase (MYLK) in endothelial cells. Activated MYLK promoted MyD88 and IRAK4 interaction leading to activation of TLR4 signaling. Our findings therefore identified TRPC6 as an essential switch that “turns on” LPS‐induced increase in lung vascular hyper‐permeability and lung inflammation. Thus, strategies aimed at blocking the instigating TRPC6 activity may hold the key to preventing acute lung injury.
HIF/Prolyl‐4‐Hydroxlyase Domain (PHD) on Tubular and Vascular Renal Function following nitric oxide synthase inhibition
Authors: Roberts Melvin , Oyekan Adebayo
Published: June 2021

PHD is an enzyme that degrades Hypoxia Inducible Factor alpha (HIFα), a transcription factor that activates protective genes during hypoxia. PHD, nitric oxide synthase (NOS) and heme oxygenase (HO) are expressed in the kidney and contribute to renal function. Hypoxia and NO inhibit normoxic PHD activity, accumulate HIF‐1α and enhanced renal function. However, PHD‐dependent renal function in the absence of NO is not known. We hypothesized that NO withdrawal will increase PHD activity and PHD inhibition will enhance renal responses upon NO withdrawal. Basal urine volume (UV) was 2.5 fold greater (P<0.05) in rats treated with dimethyloxalyll glycine (DMOG,), a PHD inhibitor. L‐NAME, a NOS inhibitor, increased UV (2.8 fold) and sodium excretion (2.8 fold, P<0.05) in control but not DMOG‐treated rats. DMOG increased GFR (2.9 fold; P<0.05) but LNAME decreased GFR in the control but not DMOG‐treated group. DMOG increased plasma bilirubin, index of HO activity, which increased more after LNAME. L‐NAME‐induced pressor response was greater in DMOG‐treated animals (P<0.05). Ang II (10–300 ng/kg) elicited dose‐dependent pressor responses which were greater (42±7%, P<0.05) in DMOG‐treated groups. These data suggest that PHD inhibition enhanced renal tubular function and accentuated pressor responses to AngII and NO withdrawal via mechanisms that appear to involve HO and NOS activities.
Plasma arginase promotes acute lung injury (ALI) in a rat model of trauma/hemorrhage and resuscitation
Authors: Johnson Fruzsina K , Durante William , Johnson Robert A , Stewart Ronald M
Published: June 2021

Red blood cells (RBC) and liver contain arginase that competes for L‐arginine with nitric oxide (NO) synthase. Low NO levels promote neutrophil activation which is a key mediator of ALI. Arginase is released during RBC storage and ischemic liver damage. Massive hemorrhage promotes liver ischemia and is treated by RBC transfusion. This study tests the hypothesis that increased plasma arginase activity contributes to ALI following resuscitation with stored PRBC in a rat model of trauma/hemorrhage. PRBC were prepared from rat whole blood. Male Lewis rats were implanted with femoral arterial and venous catheters (trauma), subjected to a 30% hemorrhage and resuscitated with crystalloids and fresh or stored (28 days) PRBC. Plasma arginase activity (0.2±0.1 vs 3.1±1.1 U/g protein), CINC‐1 (rat homologue of human IL 8) accumulation (1.5±0.5 vs 66.9±22.6pg/min) and pulmonary protein leak (3.4±1.4 vs 115.3±48.7μg/min) were higher in rats transfused with stored PRBC. In contrast, plasma aspartate aminotransferase activity was not different between rats transfused with fresh or stored PRBC. Transfusion with bovine arginase added to fresh PRBC increased plasma arginase activity (3.4±0.5 U/g protein), pulmonary CINC‐1 accumulation (13.9±7.7μg/min) and protein leak (41.1±8.8μg/min). Conversely, the arginase inhibitor, Nω‐hydroxy‐nor‐L‐arginine (100mg/kg IV) during resuscitation with stored PRBC decreased pulmonary CINC‐1 accumulation by 27% and protein leak by 30%. These data suggest that resuscitation with stored PRBC increases plasma arginase activity which contributes to ALI. Supported by grants AHA 0865241F (FKJ) and NIH HL074966 (WD).
Hemodynamic response after hypovolemic shock and resuscitation with low‐volume 6% hetastarch (HS) and high‐volume lactated Ringer's (LR) solution
Authors: Nunez Fiesky A. , Kislukin V. , Smith T. L. , Callahan M. F. , Burnett L. , VanDyke M. E.
Published: June 2021

Treatment of hypovolemia is a severe medical problem. HS is thought to be best, each ml restores 1.6ml of circulating volume (CV) while 1 ml of LR restores 0.25ml of CV. Researchers use HS in a volume equal to shed blood and 3:1 resuscitation with LR. HS is not used clinically in that manner and it remains unknown how HS low‐volume resuscitation compares with large volume LR.

Male SD rats were anesthetized with isoflurane, instrumented with an arterial catheter for mean arterial pressure (MAP) monitoring and carotid to jugular loop with flowprobes for ultrasound dilution cardiac output readings. Rats were hemorrhaged to a MAP of 40mmHg, maintained for 30 minutes then randomized to receive: 1) HS 6% @ 20% estimated total blood volume or 2) LR @ 3X the volume of shed blood. Hemodynamic parameters were taken at baseline, prior to resuscitation and 2 hours later. HS recovered cardiac function and central blood volume better than LR. However, HS volume expansion was so intense that Hct was so diluted it resulted in a calculated oxygen delivery equal to LR. HS caused a steep increase in HR after 60 minutes, with increased heart work. Such increase in heart work is detrimental to a strained myocardium and could result in early fatigue/failure. HS causes exaggerated osmosis that dilutes Hb and clotting factors, which may exacerbate ischemia and trigger dilutional coagulopathy. US Army uses HS for combat theater resuscitation. Civilian trauma centers still use high‐volume crystalloid resuscitation. This study helps clarify the physiology of low‐volume resuscitation.
The Role of Green Tea and Oxidative Stress in Heart Remodeling Induced by Tobacco Smoke Exposure
Authors: Pereira Elenize Jamas , Minicucci Marcos , Polegato Bertha , Portugal Priscila , Batista Diego , Modesto Pamela , Fernandes Ana Angelica , Rafacho Bruna , Matsubara Luiz , Zornoff Leonardo , Paiva Sergio , Roscani Meliza , Azevedo Paula
Published: June 2021

The objective of this study is to evaluate the role of green tea (GT) in heart remodeling induced by exposure to tobacco smoke (ETS).

Methods

Wistar rats were allocated in 3 groups: C (control – standard diet); S (smoke – standard diet); SGT (smoke + diet with GT 0,25%). After 2 months, animals were submitted to echocardiography, isolated heart study, and oxidative stress evaluation. One way anova test was performed.

Results

ETS leaded to an increase in left atrium area (C 0, 21±0, 03 ; S 0, 24±0,032; SGT 0, 2±0, 031) (p=0,02). End diastolic ventricle diameter/weight (p=0,5) and ventricle mass index (p=0,8) were similar. ETS impaired Systolic function: shortness fraction (C 59,5± 2,8; S 53,9±5, 9; SGT 54,5±4, 1) (p=0,03). No fibroses was evidenced: Hydroxyproline (C 2, 7±0, 6; S 3,0 ±0, 2 ; SGT 2, 9±0, 5 ) ( p=0, 5 ) ETS increased oxidative stress, that was attenuated by GT: hydroperoxides (C 133,4±14,6; S 175,9±11,5; SGT 132,0±15,4) (p<0,001); catalase [C 80,5(78,3–86,1); S 65,6(46,7–76,8); SGT 112,4(82,5–129,4)]; superoxide dismutase (C 19,5±1,9; S 11,2±0,8; SGT 19,9±2,2)(p<0,001); glutathione peroxidase (C 37,4±4,8 S 17,5±3,9 SGT37,8±3,7) (p<0,001).

Conclusion

It is possible that GT attenuates cardiac remodeling induced by ETS in part due to reduction of oxidative stress.
Differential regulation of oxidant generation and [Ca2+]i mobilization by adenosine A1 and A3 receptors in brain astrocytes
Authors: Gebremedhin Debebe , Jacobs Jesse , Zhang David , Rau Nicole , Harder David R.
Published: June 2021

Adenosine exerts its effects through 4 types of G‐protein‐coupled receptors, A1, A2a, A2b and A3. The functions of A1 and A3 receptors with regards to superoxide generation and Ca2+ mobilization in brain astrocytes is unknown. We investigated the effects of adenosine A1 and A3 receptors on superoxide generation and Ca2+ mobilization in cultured astrocytes. Stimulation of the A1 receptor with the adenosine A1 agonist N6‐CPA (100 nM) decreased basal superoxide level, whereas stimulation of the A3 receptor with the A3 agonist IB‐MECA (100 nM) increased superoxide production. Pretreatment with A1 receptor antagonist DPCPX (100 nM) rendered the A1 agonist to increase superoxide production, whereas the A3 antagonist MRS‐1220 (100 nM) reduced the A3 stimulated increased superoxide production. As to the effect on [Ca2+ ]i mobilization stimulation of A1 adenosine receptor with N6‐CPA 100 nM caused moderate increase in [Ca2+]i level that was exaggerated following antagonism of the A1 receptor with DPCPX, 100 nM. In contrast, stimulation of the A3 adenosine receptor with IB‐MECA (100 nM) induced a profound increase in [Ca2+]i level that was attenuated by the A3 antagonist MRS‐1220 (100 nM). These findings indicate that modulation of adenosine A1 and A3 receptors impose differential superoxide production and [Ca2+]i mobilization actions in cultured astrocytes that could be protective or injurious.
Postexercise histamine‐receptor activation contributes to VEGF expression in human skeletal muscle
Authors: Romero Steven Anthony , Hocker Austin D , Ratchford Stephen M , Dreyer Hans C , Halliwill John R
Published: June 2021

An acute bout of aerobic exercise is followed by a sustained postexercise vasodilation which is mediated by H1‐ and H2‐histamine receptors. We tested the hypothesis that this histamine‐receptor activation upregulates proangiogenic factors in previously exercised skeletal muscle. To this end, four healthy men performed unilateral dynamic knee extension for 1h at 60% of peak power. Two subjects received combined oral H1/H2‐receptor antagonism (540mg fexofenadine and 300mg ranitidine) 1h prior to exercise (Blockade); two did not (Control). Skeletal muscle biopsies were performed before exercise, immediately postexercise, and 3h postexercise. Relative mRNA abundance for vascular endothelial growth factor (VEGFa) and monocyte chemotactic protein‐1 (MCP‐1) were assessed by quantitative real‐time PCR. Before exercise, VEGFa and MCP‐1 expression were similar between Control and Blockade. Immediately after exercise, VEGFa increased 3.1‐fold for Control, but only 1.8‐fold for Blockade. Likewise, MCP‐1 increased 3.9‐fold for Control, but only 1.4‐fold for Blockade. At 3h postexercise, VEGFa increased 8.2‐fold for Control, but only 3.0‐fold for Blockade. At 3h, MCP‐1 increased 99.5‐fold for Control, but only 25.8‐fold for Blockade. These data suggest that histamine‐receptor activation contributes markedly to the generation of proangiongenic factors following an acute bout of exercise.
Effect of a simulated functional magnetic resonance imaging (fMRI) scanner on resting and exercise‐induced changes in cardiovascular (CV) function
Authors: Kates Andrew , Van Gestel Holly , Kimmerly Derek
Published: June 2021

fMRI scanning confounds real‐time recordings of brain neural and CV recordings and can produce claustrophobia‐induced anxiety. As such, separate data collection sessions are often required and the assumption made that resting and reflex‐mediated changes in CV function are consistent. This study determined if a simulated fMRI scanner affects cardiovascular function at rest, during isometric handgrip exercise (IHG) and a period of post‐exercise ischemia (PEI). On separate days, 9 healthy participants (4M/5F, 21 ± 1 years) had heart rate (HR), mean arterial pressure (MAP), and calf blood flow (CBF) measured while supine on a standard lab bed or a simulated fMRI scanner. After ~10 min of rest they performed a 90s IHG at 40% maximum force followed by 2 min of PEI (no exercise). Heart rate variability indices (HRV) and calf vascular resistance (CVR) were calculated to estimate autonomic innervation to the heart and blood vessels. At rest, CBF was lower and CVR higher (both, p<0.05) in the simulated fMRI scanner with no differences in resting HR, MAP, or HRV. No differences in the CV responses to IHG or PEI were observed between conditions. These data suggest that the fMRI environment increased resting sympathetic vasoconstriction to the calf but did not influence the CV response to IHG or PEI.
Inhibition of phosphodiesterases relaxes urinary bladder smooth muscle via activation of the large conductance voltageand Ca2+‐activated K+ channels
Authors: Xin Wenkuan , Cheng Qiuping , Soder Rupal P. , Petkov Georgi V.
Published: June 2021

Our previous studies showed that activation of cAMP signaling pathways reduces urinary bladder smooth muscle (UBSM) contractility by increasing the large conductance Ca2+‐activated K+ (BK) channel activity. Utilizing isometric UBSM tension recordings and the perforated patch‐clamp technique, we tested the hypothesis whether inhibition of phosphodiesterases (PDEs) can reduce guinea pig UBSM excitability and contractility by increasing BK channel activity. Inhibition of PDEs by 3‐isobutyl‐1‐methylxanthine (IBMX) concentration‐dependently reduced UBSM spontaneous and carbachol‐induced phasic contractions. IBMX also reduced electrical field stimulation (0.5–50 Hz)‐induced contractions of UBSM strips. Blocking BK channels with paxilline diminished the inhibitory effects of IBMX on UBSM contractility. IBMX increased the transient BK currents (TBKCs) frequency by ~3‐fold. However, IBMX did not affect the depolarization‐induced steady‐state whole‐cell BK currents. IBMX increased the frequency of the spontaneous transient hyperpolarizations by ~2‐fold and hyperpolarized the UBSM cell resting membrane potential by ~6 mV. Blocking the BK channels abolished the IBMX effect on the resting membrane potential. Our data reveal that PDEs inhibition with IBMX relaxes guinea pig UBSM via TBKCs activation and subsequent UBSM cell membrane hyperpolarization.

Supported by NIH DK084284 to G.V.P.
Exercise Periodic Breathing Impairs Functional Capacity by Reducing the Ventilatory‐Hemodynamic Efficiency in Patients with Heart Failure
Authors: Fu Tieh-Cheng , Lin Hsing-Chen , Wang Jong-Shyan
Published: June 2021

This investigation elucidated how exercise periodic breathing (EPB) influences functional capacity by modulating the ventilatory‐hemodynamic efficiency in patients with heart failure (HF). Ninety‐eight HF patients with (n=45) or without (n=43) EPB performed an incremental exercise test using a bicycle ergometer. A noninvasive bio‐reactance device was applied to measure cardiac hemodynamics, and a near‐infrared spectroscopy was employed to assess perfusion in frontal cerebral lobe and vastus lateralis muscle. Compared to non‐EPB counterparts, the patients with EPB revealed (i) smaller VO2peak and oxygen uptake efficiency slopes (OUES) and greater VE‐VO2 slopes; (ii) less cardiac output (QH) and perfusions in the frontal cerebral lobe (QC) and vastus lateralis muscle (QM) during exercise; and (iii) lower the score of the Short Form‐36 physical component and higher the score of the Minnesota Living with Heart Failure questionnaire. Peak QH, QC, and QM levels were directly related the OUES and VO2peak, and inversely related to the VE‐VCO2 slope. In multivariate analysis, the VE‐VCO2 slope was an effect modifier, which modulated the correlation between the Short Form‐36 physical score and central/peripheral hemodynamics. Therefore we conclude that EPB may reduce the ventilatory‐hemodynamic efficiency during exercise, thereby impairing functional capacity in patients with HF.
Direct hypertrophic effects of fibroblast growth factor 23 on cardiomyocytes
Authors: Green Troy M , Wetmore Lori A , Tchikrizov Vladimir , Touchberry Chad D , Stubbs Jason R , Bonewald Lynda F , Wacker Michael J
Published: June 2021

Fibroblast growth factor 23 (FGF23) is a secreted, bone derived hormone that regulates vitamin D and phosphate metabolism. Recent clinical data shows a correlation between elevated levels of serum FGF23 in patients with chronic kidney disease (CKD) and cardiac disease. Therefore, we investigated the direct effects of a pathophysiological concentration of FGF23 on cardiomyocyte hypertrophy. Using flow cytometry we observed an 18% increase in HL‐1 cardiomyocyte cell size after 48 hour exposure to 900 pg/mL FGF23 (FSC; p<0.05; n=5). These hypertrophic effects on cells were verified in ventricular muscle tissue strips where treatment of FGF23 resulted in a 2 to5 fold increase in expression of common gene markers of cardiac hypertrophy (n=4–7; p<0.05) and elevated ERK1/2 phosphorylation (n=4; p<0.05). We also observed a 10% increase in total protein concentration which was blocked with an FGFR1 inhibitor (n=5–7; p<0.05). These data show that FGF23 has direct effects on cardiomyocyte cell size and may be an important bone‐heart crosstalk regulator of cardiac hypertrophy. This may be of particular importance with certain bone diseases and CKD where FGF23 levels are elevated. This work was supported by AHA SDG 11SDG5330016 (MJW) and NIH NIAMS 1RC2AR058962 (MJW and LFB).
Aging, inflammation and skeletal muscle
Authors: White Thomas A , Zhu Yi , Giorgadze Nino , Tchkonia Tamar , Kirkland James L , LeBrasseur Nathan K
Published: June 2021

Inflammation is a hallmark of aging and a likely contributor to skeletal muscle loss (sarcopenia). We investigated whether the inflammatory phenotype of differentiated primary skeletal muscle‐derived cells (SkMDCs) from a 17‐year‐old (young) differed from that of a 68‐year‐old (older) donor. Under basal conditions, expression of genes encoding pro‐inflammatory cytokines was in fact lower in older compared to younger SkMDCs. However, in response to lipopolysaccharide (LPS), these factors were more highly upregulated in older cells. Specifically, in young compared to older SkMDCs, interleukin‐6 (IL‐6) increased 3‐ vs. 9‐fold, tumor necrosis factor‐alpha (TNF‐alpha) increased 11‐ vs. 80‐fold, and IL‐1alpha increased 14‐ vs. 21‐fold (all differences were p < 0.01). Given adipose tissue is a primary source of pro‐inflammatory stimuli and infiltrates skeletal muscle with age, we hypothesized that secreted factors from senescent preadipocytes drive a similar molecular phenotype to LPS. Exposure of SkMDCs to conditioned medium from senescent‐preadipocytes increased expression IL‐6 and TNF‐alpha in young and even more so in older cells (both p < 0.05). Thus, there are inherent differences in the molecular inflammatory phenotype and its response between young and older SkMDCs. These data also suggest that the age‐related accumulation of senescent preadipocytes may contribute to sarcopenia.
Iron deficiency causes a shift in AMP‐activated protein kinase (AMPK) catalytic subunit composition in rat skeletal muscle
Authors: Merrill John Floyd , Hepworth Squire D. , Willie Shelby , Winder William W. , Thomson David M. , Hancock Chad R.
Published: June 2021

To determine effects of iron deficiency on LKB1/AMPK signaling, rats were fed a control (C=0.29 mg/g Fe) or iron deficient (ID=0 mg/g Fe) diet for 8 wks resulting in hematocrits of 47.5% ± 1.0% and 16.5% ± 0.6% respectively. Iron deficiency resulted in 28.3% greater muscle fatigue (p<0.01) in response to 10 min of stimulation (1 twitch/sec) and was associated with a greater reduction in phosphocreatine (C: 45.6%; ID: 85.9%) and ATP levels (C: 0%; ID: 24.0%). AMPK activation increased with stimulation in muscles of C and ID animals. A reduction in Cytochrome c and other heme‐containing mitochondrial proteins was observed in ID animals (p<0.01). The two isoforms of the AMPK catalytic subunit (α) are known to sense and respond differently to energy challenges. In ID animals, the AMPKα2 subunit protein content was reduced by 28.4% (p<0.05), however this did not result in a significant difference in resting AMPKα2 activity. AMPKα1 protein was unchanged, however an overall increase in AMPKα1 activity was observed (C: 1375.8 pmol/mg/min; ID: 2229.8 pmol/mg/min, p<0.01). Resting phospho Acetyl CoA Carboxylase (pACC) was also increased by 17‐fold (p<0.05), indicating greater AMPK activity that was not determined by the AMPK activity assay. This study indicates that chronic iron deficiency causes a shift in the expression of AMPKα subunit composition and potentially altered sensitivity to cellular energy challenges.
The manner of metabolism is different between the atrium and the ventricle
Authors: Shimura Daisukie , Jiao Qibin , Kashikura Kasumi , Endo Keiko , Soga Tomoyoshi , Goda Nobuhito , Minamisawa Susumu
Published: June 2021

Energy of the cardiac muscle largely depends on fatty acid oxidation (FAO). It is known that the atrium and the ventricle have tissue‐specific functions, structures, gene expressions, and pathologies. The ventricle pumps blood and its muscle wall is thicker than atrial wall. Thus, energy utilization should be different between them. However a tissue‐specific pattern of cardiac metabolism remains incompletely understood. Recently, innovative techniques have enabled comprehensive analysis of metabolites. Therefore, we aimed to clarify differences between the atrium and the ventricle and used male C57B6 mice at the age of 6 weeks to comprehensively measure metabolites of their atria and ventricles by capillary electrophoresis and mass spectrometry.

We found that the metabolic pattern was significantly different between them. The levels of lactate, acetyl CoA, and succinate in the ventricles were higher than the atrium. Moreover, N‐acetyl aspartate (NAA) and acetylcholine were higher in the atrium than the ventricles.

Our data suggest that energy metabolism of the ventricle is more active than the atrium and depends on not only FAO but also glycolysis with lactate fermentation, whereas that of the atrium largely depends on FAO. Furthermore, the atrium is innervated and NAA might be a molecular marker of it.

We hope these findings contribute to better understanding of tissue‐specific characters and pathologies.
Hypoxia‐induced muscle atrophy involves direct and indirect signaling towards protein turnover regulation
Authors: De Theye Chiel Charles , Koehler S Eleonore , lamers Wouter H , Schols Annemie M.W.J. , Langen Ramon J.C.
Published: June 2021

Background

As COPD patients may experience hypoxemic episodes, we hypothesized that subsequent tissue hypoxia is a trigger of COPD‐associated skeletal muscle atrophy.

Methods

Mice were kept under normoxia or hypoxia. Oxygen levels were reduced stepwise to 8% during 48h, and maintained for 21 days. Food intake was monitored and mice were sacrificed at days 4 and 21. To discern direct and indirect effects of hypoxia, fully differentiated C2C12 myotube cultures were exposed to hypoxia (4% O2).

Results

Hypoxia induced hypoxemia, acidosis, erythremia. Gastrocnemius muscle weight decreased, which was only in part attributable to hypophagia. Comparing hypoxia with pair‐fed, expression of ER‐stress markers Atf4 and Gadd34, were increased as a direct effects of hypoxia and at day 4 partially by hypophagia. Protein synthesis was induced evidenced by reduced p‐eIF2α levels and increased mTOR signaling. Foxo‐1 activity and expression were directly induced by hypoxia and at day 4 by hypophagia. Gene expression associated with autophagy and ubiquitin 26S proteasomal degradation was induced and at day 4 partially attributable to hypophagia. As opposed to MuRF1, Atrogin‐1 and LC3B, Bnip3 expression was directly regulated by hypoxia.

Conclusion

: Hypoxia‐induced muscle atrophy is characterized by signaling suggestive of increased muscle protein turnover.

Supported by the Dutch Top Institute Pharma (project # T1‐201).
Influence of different classes of anesthetics on burst‐to‐burst variability of basal phrenic nerve discharge in adult in vivo rat
Authors: Rahim Tania , Kiridly Adam , Reid Inefta M , Solomon Irene C
Published: June 2021

The respiratory control system is highly dynamic, allowing for breath‐to‐breath adjustments to both physiological and pathological conditions. Ongoing work in our laboratory in the adult in vivo rat focuses on exploring the influence of different classes of anesthetics on various respiratory behaviors, including basal respiratory burst patterns. In the current study, we expand on this work by examining the influence of different classes of anesthetics on burst‐to‐burst variability of basal phrenic nerve discharge. Poincaré plot and coefficient of variation analyses were performed on 300 consecutive phrenic bursts obtained from urethane (U), inactin used alone (IN) or in combination with ketamine (IN‐K) or xylazine (IN‐X), sodium pentobarbital (P), ketamine in combination with xylazine (K‐X), propofol (PRO), and isoflurane (ISO) anesthetized rats; decerebrate rats were also studied. Our analyses suggest that different classes of anesthetics differentially influence the short‐term and long‐term variability of phrenic burst frequency and timing, and that typically used measures of variability may not fully capture long‐term patterns of variability. Supported by HL63175
Regulation of renal organic anion transporter expression and function in ACTH‐treated mice
Authors: Bailey Matthew A. , Kenyon Christopher J
Published: June 2021

Our previous renal microarray studies indicated differential expression of genes encoding organic anion transporters in a mouse model of ACTH‐dependent Cushing syndrome (Physiological Genomics 40: 158, 2010). In the current study, we used quantitative PCR to show significantly (P<0.01) reduced expression of genes encoding OATP‐1 (slco1a1), OAT2 (slc22a7) and OAT3 (slc22a8) in the kidneys of ACTH‐treated mice (n=6/6). In separate groups of mice, a 14‐day treatment with ACTH (n=5) caused hypertension, polyuria and a four‐fold increase in uric acid excretion, compared to controls (n=6). This is consistent with down‐regulation of OAT3, which contributes to the reabsorption of uric acid. ACTH‐treated mice also had a significantly reduced renal clearance of p‐aminohippurate (cPAH), a prototypical substrate of the OAT system. Since cPAH was not affected by co‐administration of probenecid, it is likely that organic anions normally secreted via this pathway are largely excreted by filtration during chronic glucocorticoid excess. These data indicate that organic anion transport in the kidney is physiologically regulated by corticosteroids. Since several classes of drugs are excreted via this pathway, our data have therapeutic implications in conditions of steroid excess.
Insulin Activates Intestinal NHE3 via IRBIT
Authors: He Peijian , Yanda Murali , Anitha Mallappa , Srinivasan Shanthi , Yun Chris
Published: June 2021

Diarrhea is a troublesome intestinal complication of diabetes. The estimates for the prevalence of diarrhea in diabetic patients reach more than 20%. The goal of this study is to determine whether the major intestinal Na+/H+ exchanger NHE3 contributes to diabetic diarrhea. We found that induction of diabetes by streptozotocin resulted in a significant decrease in NHE3 activity and retrieval of NHE3 from the plasma membrane into the cytoplasmic pool. Decreased NHE3 activity was partially restored with i.p. injection of insulin. Insulin acutely increased NHE3 activity in intestinal epithelial SK‐CO15 cells via a PI3K‐dependent mechanism. IRBIT, IP3 receptor‐binding protein released with IP3, mediates NHE3 activation by Ca2+ and angiotensin II. Knockdown of IRBIT markedly attenuated activation of NHE3 by insulin. We found that insulin induced mobility shift of IRBIT protein, indicating phosphorylation of IRBIT, and enhanced the interaction between NHE3 and IRBIT. IRBIT was found to interact with NHERF1 and knockdown of IRBIT decreased the NHE3‐NHERF1 association, suggesting that IRBIT mediate the interaction between NHE3 and NHERF1. In conclusion, IRBIT and NHERF1 are necessary for stimulation of NHE3 by insulin. (This study was supported by NIH grant DK060418)
Dietary fat‐induced taurocholic acid production promotes pathobiont and colitis in IL‐10−/− mice
Authors: Devkota Suzanne , Wang Yunwei , Leone Vanessa , Musch Mark , Nadimpalli Anuradha , Antonopoulos Dion , Jabri Bana , Chang Eugene
Published: June 2021

The composite human microbiome of Western populations has changed over the past century, brought on by new environmental triggers that often have a negative impact on human health. Here we show that consumption of a diet high in saturated (milk derived)‐fat (MF) but not polyunsaturated (safflower oil)‐fat (PUFA) changes the conditions for microbial assemblage and promotes expansion of a rare, immunogenic, sulfite‐reducing pathobiont, Bilophila wadsworthia. This was associated with a proinflammatory TH1 immune response and the development of colitis in genetically susceptible IL‐10−/− mice. Because MF promotes the formation of taurine‐conjugated hepatic bile acids (a sulfur source for B. wadsworthia), we examined the possibility that the MF effects are mediated by changes in bile composition. Only bile obtained from MF‐fed mice promoted B. wadsworthia growth in vitro. In addition, a bloom of B. wadsworthia and development of colitis was seen when mice were fed a low‐fat (LF) diet supplemented with taurocholic, but not with glycocholic acid. Furthermore, when germ‐free IL‐10−/− mice were monoassociated with B. wadsworthia, the bacteria survived only when provided with the MF diet or taurocholic acid, and resulted in colitis, which was not observed when MF or taurocholic acid were fed alone. Together these data show that dietary fats differ in their effects on the host microbiota and immune system. The data also provide a plausible mechanistic basis by which Western type diets high in saturated fats may increase the prevalence of complex immune‐mediated diseases like inflammatory bowel diseases in genetically susceptible hosts.
Multiple Players Vying for One Target: Regulation of Differential Signaling Fate of Corticotropin‐releasing Factor Receptor 1 (CRF1)
Authors: Mahajan Shilpi , Hasdemir Burcu , Liao Min , Bhargava Aditi
Published: June 2021

Activation of CRF1 by CRF, urocortin (Ucn1) or both, is critical in stress‐related pathophysiological conditions like anxiety, depression, and irritable bowel syndrome. We sought to determine how CRF1 activation by multiple ligands evokes distinct cellular responses. Mass spectrometry and HPLC showed endothelin‐converting enzyme‐1 (ECE‐1) differentially degrades CRF and Ucn1; ECE‐1 cleaves Ucn1, but not CRF, at critical residue Arginine‐34/35’, which is essential for ligand‐receptor binding. ECE‐1 cleavage disrupts the Ucn1‐CRF1 complex to alter Ucn1‐, but not CRF‐mediated Ca2+ mobilization. ECE‐1 inhibition disrupted Ucn1‐, but not CRF‐induced CRF1 recycling and re‐sensitization, but did not prolong the association of CRF1 with β‐arrestins (βARRs). Ucn1‐, but not CRF‐induced CRF1 recycling was dependent on Rab11 activity and re‐sensitization was dependent on both Rab4 and Rab11 activity. CRF1 behaves like a class A GPCR with respect to transient βARR interaction, but like a class B GPCR with respect to slow recycling. We propose a novel mechanism by which two ligands acting on the same receptor can result in distinct re‐sensitization and downstream signaling– differential degradation by ECE‐1.

NIH DK080787 and Hellman Family Foundation grant to AB.
Contribution of sugar‐sweetened beverages and refined grains to dietary sugar among postpartum Latinas
Authors: Vega-López Sonia , Pignotti Giselle AP , Williams Allison Nagle , Belyea Michael , Records Kathie , Ainsworth Barbara E , Permana Paska , Coonrod Dean V , Keller Colleen S
Published: June 2021

Three 24‐h diet recalls were collected from 140 postpartum Latinas (28.3±5.6 y, BMI=29.7±3.5 kg/m2) enrolled in Madres Para la Salud, a social support‐mediated walking intervention, to identify sources of dietary sugars. Energy (E) intake was 1464±527 kcal/d, with 31±7% E from fat and 16±4% E from protein. Fiber intake was low (9.2±3.1 g/1000 kcal/d). Total sugar intake was 93±41 g/d (26±7 %E), of which 63±35 g/d (17±7 %E) were from added sugars. Added sugar intake was positively correlated with energy (r=0.598, p<0.005), total fat (r=0.426, p<0.0001), and trans fatty acids (r=0.503, p<0.0001). Relative to participants with added sugar intake below the median (58 g/d), those with greater intake consumed significantly more sugar‐sweetened beverages (2.1±1.1 vs. 0.6±0.6 servings/d, p<0.0001), soft drinks (1.4±1.0 vs. 0.4±0.5 servings/d, p<0.0001), grains (6.3±2.1 vs. 4.9±2.3 servings/d, p<0.0001), refined grains (3.4±1.8 vs. 2.7±1.9 servings/d, p<0.05), and sweetened pastries (0.66±0.72 vs. 0.27±0.35 servings/d, p<0.0001). Results suggest that sweetened beverages and refined grain products are important contributors to sugar and energy intake in this population. Because the postpartum period is a critical time for the loss of pregnancy‐associated weight gain, interventions for reducing intake of sugar and refined grain products in this population are warranted. Supported by NIH 3R01NR010356‐02S1.
Determination of cranberry proanthocyanidin A2 in human plasma and urine using LC‐MS/MS
Authors: Zampariello Carly A. , McKay Diane L , Dolnikowski Gregory , Blumberg Jeffrey , Chen C-Y. Oliver
Published: June 2021

A‐type proanthocyanidins (PAC) exhibit anti‐adhesion activity against uropathogenic Escherichia coli in vitro, putatively protecting against urinary tract infections. However, data on PAC bioavailability in humans has not been established due to lack of a method for their quantification. We conducted a single‐dose pharmacokinetic study to quantify PAC A2 (A2) in urine and plasma of 10 healthy adults. Fasted subjects consumed 237 mL low‐calorie, low‐sugar 54% cranberry juice cocktail (CJC). Blood and urine samples were collected at specified intervals before and up to 24 h following CJC consumption. Prior to LC‐MS/MS analysis of urinary A2, liquid‐liquid extraction using ethyl acetate and solid phase extraction (SPE) were sequentially employed to extract A2 and minimize matrix‐induced MS signal depression. A2 was extracted from plasma using SPE only. The limit of quantitation (LOQ) for A2 was 1.25 ng/mL in urine and 2.5 ng/mL in plasma. The recovery rate of A2 spiked into urine was 12%. The intra‐ and inter‐assay CV for A2 spiked into urine were 9.8% and 10.6%, respectively. The maximal concentration of A2 in urine was 24.4 ng/mg creatinine at 11.0 h post ingestion, while A2 was detected in plasma at concentrations below the LOQ. This study demonstrates for the first time the bioavailability of A2 following CJC consumption. The detected A2 in urine may be derived from the beverage and via metabolism by gut microflora.
Fat flu: the obese host in influenza virus evolution
Authors: Karlsson Erik , Schultz-Cherry Stacey
Published: June 2021

During the 2009 influenza pandemic, obesity was identified as an independent risk factor for increased disease severity and mortality. These epidemiological findings have been confirmed using obese mouse models. Previous studies in mice have demonstrated that nutritional status can affect virulence of RNA viruses including influenza. The global epidemic of obesity combined with increased disease severity in obese subjects prompted us to question whether obesity could influence influenza virus evolution. To determine if the obese lung microenvironment could differentially affect viral adaptation, A/California/04/2009 influenza virus was passaged five times in either lean or diet‐induced obese (DIO), C57Bl/6 male mice. Lean and DIO mice were then infected with parental and passaged viruses and monitored for morbidity and mortality. Interestingly, virus passaged in DIO mice induced greater morbidity, pathology and mortality in both lean and DIO animals compared to lean‐passaged virus. Studies are underway to define the molecular determinants associated with the enhanced pathogenicity; however, the obese virus retained increased pathogenicity following egg passage suggesting genetic changes to the virus itself. These studies suggest that the expanding obese population may not only be more susceptible to disease, but may differentially regulate viral evolution towards more virulent viral strains.

Grant Funding Source: NIH NIAID contract number HHSN266200700005C and the American Lebanese Syrian Associated Charities (ALSAC)
Integration of PBL cases into gross anatomy laboratory experiences followed by a modified TBL formative assessment: pedagogy using the best of both worlds
Authors: Wisco Jonathan J. , Korin Tatum Langford , Wimmers Paul , Stark M. Elena
Published: June 2021

A hybrid curriculum consisting of PBL, small group learning, didactics and laboratory activities often lack pragmatic continuity of educational experiences. In this study, we ascertained student opinions of PBL integration with gross anatomy lab sessions covering topics of the head and neck, thorax, abdomen and pelvis. Student anatomy teams in 2010 were asked to answer PBL integration questions at the end of 5 (of 8) lab sessions. Eleven 1st year student volunteers participated in a 1‐hr semi‐structured focus group to assess the experience. Proceedings were recorded (students’ identification was anonymous) and transcribed. Students expressed that 1) PBL was an important feature of the overall curriculum, helpful for learning lecture material in greater depth, and essential for achieving active and critical learning, teamwork, and literature search skills; and 2) a didactic approach to integration questions throughout lab exercises with a discussion of the answers at the end of lab, and standardized instruction by tutors on follow‐up PBL sessions would be very helpful to their experience. Based on this feedback, we are currently repeating the study in 7 similar laboratory sessions, this time adding a modified TBL component for formative assessment. We discuss the evolution of anatomy pedagogy from a stand‐alone course to a fully integrated foundational experience in our medical curriculum.
Effect of trichloroethylene exposure on autoimmune‐mediated cholangitis in NOD.c3c4 mice
Authors: Sullivan Bradley P. , Kassel Karen M. , Luyendyk James P.
Published: June 2021

Primary biliary cirrhosis (PBC) is characterized by autoimmune‐mediated destruction of bile ducts and has both genetic and environmental components. Specific chemicals that cause PBC have not been identified. Previous studies have shown that trichloroethylene (TCE) exposure promotes autoimmunity. We evaluated the capacity of TCE exposure to enhance liver disease in a mouse model of cholangitis. NOD.c3c4 mice spontaneously develop autoimmune‐mediated liver disease with features resembling PBC including portal inflammation and fibrosis. Nine week old NOD.c3c4 mice were exposed to TCE (0.5 mg/ml) or its vehicle (1% Cremaphor‐EL) via drinking water for 4 weeks. TCE exposure increased serum alanine aminotransferase (ALT) activity and serum bile acid levels in NOD.c3c4 mice, but did not affect biliary cyst area, another feature of liver disease in these mice. Interestingly, TCE exposure suppressed mRNA levels of early growth response 1 (Egr‐1), a transcription factor shown to limit fibrosis. Of importance, TCE exposure increased hepatic collagen expression in NOD.c3c4 mice. In contrast, NOD.ShiLtj mice exposed to TCE did not develop liver disease or fibrosis. These results suggest that TCE exposure enhances liver disease in NOD.c3c4 mice, and further highlights the possibility of utilizing these mice to study gene‐environment interactions critical for development of autoimmune‐mediated liver disease.
Enhanced aldosterone synthesis and insufficient activation of cyp2c9‐EET pathway in the brain play a pivotal role in salt‐induced sympathetic activation in mice with pressure overload
Authors: Ito Koji , Hirooka Yoshitaka , Sunagawa Kenji
Published: June 2021

Background

Recently, we demonstrated that high‐salt (HS) intake augments sympathetic drive via brain mineralocorticoid receptor (MR) – epithelial Na channels (ENaCs) pathway activation in mice with pressure‐overload (PO‐mice). In the present study, we determined whether imbalance between aldosterone synthesis and activation of cyp2c9‐EET plays a pivotal role in sympathetic activation in this model.

Methods and Results

We performed aortic banding to create PO‐mice. Sham operation was performed as control (Sham‐mice). Four weeks after aortic banding, mice were fed with either a HS (8%) diet or a regular‐salt diet for additional 4 weeks. Urinary norepinephrine excretion, a marker of sympathetic activity was significantly increased by HS in PO‐mice, but not in Sham‐mice. The expressions of brain MR and the ratio of phosphorylated/total serum glucocorticoid inducible kinase‐1(sgk‐1), a marker of MR activity increased in PO‐mice. Furthermore, unlike in Sham‐mice, PO‐induced MR activation maintained despite HS loading. Intracerebroventricular (ICV) infusion of aldosterone synthesis inhibitor, FAD 286A (100 μg/kg/day, 4 weeks), decreased brain MR activity with the reduction of sympathetic drive. We also examined the cyp2C9 expression and 11,12‐epoxyeicosatrienoic acids (EET) concentration in the brain, a major pathway to inhibit ENaCs. HS increased cyp2c9 expression and 11,12‐EET concentration in the brain only in Sham‐mice, but not in PO‐mice.

Conclusion

In PO‐mice, HS increases sympathetic drive via the activation of brain MR‐ENaCs pathway through aldosterone‐dependent MR activation and insufficient activation of cyp2c9‐EET pathway.
The shape, size, and asymmetry of fetal hippocampal formation during the second trimester: A 7.0 Tesla postmortem MRI study
Authors: Liu Shuwei , Liu Jun , Zhang Zhonghe , Teng Gaojun , Fang Fang , Zang Fengcao
Published: June 2021

Objective

The purpose of this study is to find morphometric changes of the HF during the second trimester.

Material and methods

46 fetal specimens with gestational ages(GA) of 13–22 weeks were scanned with a Bruker 7.0T MR Scanner. The MR image data were analyzed and post‐processed with Amira 4.1. Three‐dimensional structures were produced and volumes of the labeled HF were calculated.

Results

With 7.0T MRI, some morphological appearances were delineated. Before 16 to17 weeks, the HF is just a flat structure. Then, the HF becomes cylindrical structure with an impressive hippocampal sulcus. The left and right hippocampuses demonstrated significant increases in volume with gestational age (Left: R=0.8663, Right: R=0.889). The two side HF volumes were tested by Wilcoxon signed‐rank test. The right HF was larger than the left one.

Conclusion

During the period, the volume growth of HF is a significantly positively correlated with age in weeks and there is asymmetrical growth in volume.
Capsaicin induces apoptosis in human small cell lung cancer via the TRPV pathway
Authors: Crabtree Clayton M. , Dom Aaron M. , Lau Jamie K. , Brown Kathleen C. , Shiflett Brandon S. , Witte Theodore R. , Hardman W. Elaine , Dasgupta Piyali
Published: June 2021

Capsaicin, the spicy ingredient of chili peppers, is used to topically treat pain and inflammation associated with a variety of diseases. However, emerging evidence shows that it can induce apoptosis in different transformed cell types in vitro and in animal models. The present study examines the apoptotic activity of capsaicin in human small cell lung cancer (SCLC). Here we show that capsaicin induced apoptosis in a panel of human SCLC in a concentration‐dependent and time‐dependent manner. Most importantly, capsaicin caused 5–6 fold apoptosis in a panel of human SCLC cell lines, but did not affect normal human lung epithelial cells. The dietary administration of capsaicin decreased the growth of H69 and DMS53 human SCLC tumors xenotransplanted in nude mice. The apoptotic activity of capsaicin was independent of TRPV1, the known receptor for capsaicin. In contrast, depletion of TRPV6 by siRNA ablated the apoptotic activity of capsaicin. Our findings suggest that capsaicin may have potential applications as a novel agent for management and therapy of human SCLCs.
Bioactive Nanomaterials for Enhanced Wound Healing
Authors: Balkawade Rohan Sambhaji , Mills David Keith
Published: June 2021

Wound healing has become a significant problem for patients, doctors and the US health care system, affecting millions of people and costing billions of dollars. Several biodegradable and non‐toxic materials are under research to develop a biomolecular environment for wounds that will enhance the healing process. One of the methods is developing a polyelectrolyte nanofilm multilayer's (PNMs) as a nanocoating on the surface of the wound embedded with growth factors. The PNMs is developed using an ultrasonic nebulizer (UN) by spraying oppositely charged polyelectrolytes over the skin (Epiderm full thickness which is a human skin equivalent). By using UN we can control rate of deposition/concentration, time, and thickness of PNMs. Oppositely charged, Poly‐L‐Glutamic acid (PGA) and Poly‐L‐Lysine (PLL) served as a basic architecture for the nanofilm in which platelet derived growth factor (PDGF‐B) and insulin like growth factor (IGF‐1) were incorporated in deep (D), double (DL), and combined layer (CL). PNMs embedded with PDGF and IGF showed increased epithelization, connective tissue formation, and collagen deposition when compared with the controls. These results suggest that PNMs act as a bioactive and biodegradable drug delivery system to enhance the wound healing process.

Research support: Governor's Biotechnology Initiative.
Interferon Regulatory Factor 6, a novel transcriptional regulator of embryonic development and wound healing
Authors: Biggs Leah C , Le Mark , Rhea Lindsey , Kinoshita Akira , Murray Jeff C , Schutte Brian C , Dunnwald Martine
Published: June 2021

Cleft lip and palate (CLP) constitutes the second most common congenital birth defects in the US. This complex trait results from a disruption of the highly coordinated growth, migration and fusion of facial prominences during early embryological development. Evidence from genetic studies, animal models, and expression data suggest a variety of candidate genes for CLP. Amongst them, Interferon Regulatory Factor 6 (IRF6) is unique because DNA variation in this gene both causes and contributes significant risk for orofacial clefts. IRF6. Loss of function of IRF6 in human causes two orofacial syndromes, Van der Woude (VWS) and Popliteal Pterygium. In the mouse, deletion of Irf6 leads to craniofacial anomalies, as well as limb and cutaneous defects. These data support a role for Irf6 in embryonic development. Recent clinical chart review of patients with orofacial clefts indicated that patients with VWS were more likely to develop wound complications after corrective cleft surgery compared to patients with an isolated cleft, suggesting that IRF6 plays an additional role in wound healing. We took advantage of the murine model to culture keratinocytes from wildtype and Irf6‐deficient animals. Our in vitro data indicate a delay in scratch closure in the absence of Irf6. Potential molecular mechanisms beyond this observation will be presented, along with novel in vivo wound healing models.

DE16215 and AR055313