bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physiological Significance of Mitochondrial Uncoupling Protein 1 in the Prevention of Reactive Oxygen Species and Control of Substrate Oxidation
Authors: Jastroch Martin , Keipert Susanne , Meyer Carola W , Kutschke Maria , Heldmaier Gerhard , Klaus Susanne , Oelkrug Rebecca 
Published: June 2021

The established function of mitochondrial uncoupling protein 1 in mammalian brown adipose tissue is the dissipation of proton motive force as heat. Uncoupling of respiration may also prevent mitochondrial superoxide production and ROS formation, but the involvement of UCP1 in this process is highly disputed. We here studied in isolated mitochondria a) whether the presence of endogenous uncoupling protein 1 in brown adipose tissue affects superoxide production, in particular during cold acclimation and beta oxidation, b) whether ectopically expressed UCP1 in skeletal muscle is functional and manipulates superoxide, and c) how substrate oxidation adapts to the presence of UCP1.We show that UCP1 mitigated mitochondrial superoxide rates in both tissues. In brown adipose tissue, increases of superoxide during cold acclimation and beta oxidation were blunted as compared to UCP1 knockout mice. Uncoupling alters oxidation capacities differently depending on cell‐type: While the presence of UCP1 in brown adipose tissue allows cold‐induced increase in oxidative capacity, skeletal muscle UCP1 depresses substrate oxidation. Our results demonstrate the physiological involvement of UCP1 in the regulation of mitochondrial superoxide and provide models to further investigate how uncoupling controls oxidative capacity by altering superoxide and/or cellular ATP/ADP ratios.
Stimulation of P2X7 receptors causes Ca2+‐ and PKC‐mediated reactive oxygen species production in murine macrophages
Authors: Martel‐Gallegos Guadalupe , Casas‐Pruneda Griselda , Ortega Filiberta , Sanchez‐Armass Sergio , Perez‐Cornejo Patricia , Arreola Jorge 
Published: June 2021

Stimulation of macrophages with extracellular ATP or Bz‐ATP induces Reactive Oxygen Species (ROS) production. We tested the idea that in J774 macrophages activation of P2X7 receptors (P2X7R) by ATP leads to NADPH oxidase assembly and ROS production via Ca2+ entry and PKC activation. We used whole‐cell voltage clamp to measure P2X7R‐mediated currents, Fura‐2 to determine [Ca2+]i, 2′,7‐dichlorodihidrofluorescein to assay ROS production, PCR and western blot for P2X7R expression and phospho‐specific antibodies to determine activation of PKC isoforms. Stimulating J774 cells with Bz‐ATP (100 μM) induced an inward current at −80 mV that was sensitive to A438079 (10 μM), a blocker specific for P2X7R. ROS production induced by Bz‐ATP was also inhibited by A438079, PKC inhibitors and by removing extracellular Ca2+. Similarly, the increase in [Ca2+]i seen with Bz‐ATP was inhibited by zero external Ca2+ and A438079. Bz‐ATP induced PKC α activation. Importantly, Bz‐ATP induced a transient activation of PKC δ, while PKC ζ displayed an oscillatory pattern and was inhibited by A438079, confirming the participation of P2X7R. In summary, we propose that purinergic stimulation in macrophages induced ROS production due to Ca2+ entry via P2X7R and subsequent PKC activation which may, in turn, induce NADPH oxidase assembly and activation.Supported by grants 79897 and 105457 to JA and P. P‐C
Characteristics of early‐stage experimental middle cerebral occlusion‐reperfusion
Authors: Park Sookyoung , Lee Sang‐kil , Chang Kyu‐tae , Hong Yonggeun 
Published: June 2021

Middle cerebral artery occlusion (MCAo)‐reperfusion microsurgery induces focal cerebral ischemia (FCI) and neurological deficiency. Recently, it was reported that integral membrane proteins known as caveolins (cav) may be involved in the pathogenesis and mechanism of cerebral ischemia. Therefore, in this study we established the behavioral features and investigated the expression of cav and signaling molecules in rat brains subjected to MCAo. All rats were evaluated for neurological and motor dysfunction using the modified neurological severity score (mNSS), gait analysis, and beam‐walking test at 24, 48, and 72 h after MCAo. Next, the brains of the rats were cut into 2‐mm thick coronal sections, which were subjected to TTC staining for confirmation of the infarct volume. On assessing the behavior of the MCAo rats, neurological deficiency, motor dysfunction, and impaired balance were detected (p<.05). Moreover, the gene expression of cav, nNOS, BDNF, and Trk family was decreased, whereas iNOS gene expression was increased in the MCAo group, as compared to the control group, at 24 h after microsurgery (p<.05). Also, the cerebral infarct volumes were increased significantly in the MCAo group, as compared to the control group (p<.05). These results imply that cav and signaling molecules, especially iNOS, are a strong causative factor in the early stages of brain damage after FCI.Funding: BioGreen21 Program (Code No. 20070401‐034‐006‐009‐02‐00), Rural Development Administration, Korea
The effects of exogenous hormones on maximal and submaximal responses to high intensity interval training
Authors: Zierke Jennifer Marie , Turner Rebekah Joy , Parker Daryl , Quintana Roberto 
Published: June 2021

High intensity interval training (HIIT) leads to VO2max improvements in 2‐weeks (Talanian, 2007). Long term (≥ 4 months) exogenous hormone (EH) use can decrease VO2max by 11% (Casazza, 2002). It is unknown whether EH impairs exercise training induced adaptations.PURPOSEThe purpose of this study was to investigate the effects of seven HIIT sessions over 2 weeks on maximal and submaximal (submax) physiological responses to exercise in women taking EH.METHODSSixteen healthy women of average fitness, VO2max = 40.29±7.51, volunteered for this study (n=8 EH, n=8CON). Prior to participating in the study, the EH women were taking a monophasic or triphasic oral contraceptive pill for ≥ 6 months and CON were regularly menstruating. VO2max and submax testing (10% below VT1) were performed on a cycle ergometer pre and post HIIT. Statistical comparisons were made between EH and CON to determine the physiological adaptations that occurred with HIIT.RESULTSCON had a significant decrease in submax HR (148±6.1vs136±4.7bpm, p=0.02), and an increase in O2pulse (10.36±.81vs10.98±.81 ml/bpm, p=0.02). The EH had a significant increase in dBP (59.7±3.0vs65.2±3.12mmHg). There were no other significant differences between groups.CONCLUSIONEH use alters submax cardiovascular training responses without affecting VO2max. EH use blunts HR, dBP, and O2pulse adaptations to HIIT.
Heat acclimation reduces gut permeability, endotoxin translocation, and inflammatory/anti‐inflammatory cytokine cascades in humans
Authors: Kuennen Matthew Ryan , Gillum Trevor , Christmas Kevin , Kulovitz Michelle , Alumbaugh Brent , Dokladny Karol , Schneider Suzanne 
Published: June 2021

PurposeTo examine human gut barrier responses to a 7‐day heat acclimation (HA) protocol.MethodsFive men exercised to a core temperature of 39.20 ± 0.04°C for 7 days to develop HA. Blood drawn pre (Pre) and post (Post) exercise on day 1 and day 7 of HA was assayed for endotoxin, TNF‐a, Il‐6, Il‐10, intracellular (iHSP70) and extracellular HSP70 (eHSP70). Additional measures of gut permeability (lactulose sugar test) were performed at baseline (prior to exercise/heat exposure) and on days 1 and 7 of HA.Results

HA Day 1
HA Day 7

Pre
Post
Pre
Post

Endotoxin (pg/ml)
7.8±1.8
10.7±2.3*
4.8±0.7^
7.7±2.7^

Lactulose (fold Δ from baseline)
‐
11.1±6.4*
‐
6.7±3.3

TNF‐a (pg/ml)
10.9±0.9
13.2±1.5*
10.4±1.0
10.5±1.1#

Il‐6 (pg/ml)
1.3±0.4
6.8±1.7*
1.2±0.5
2.9±0.6*#

Il‐10 (pg/ml)
7.5±2.7
20.3±5.3*
7.5±1.5
10.5±2.4#

eHSP70 (ng/ml)
0.7±0.4
1.5±0.8*
1.4±0.4
1.3±0.5

iHSP70/actin (pixels)
0.3±0.1
0.6±0.1*
0.2±0.07
0.9±.04*#

Data are mean ± SE.
difference within conditions, p<.05.
difference between conditions, p<.05.
difference between conditions, p <.07

ConclusionsBoth direct (endotoxin) and indirect (lactulose sugar test) measures support a reduction in exercise‐induced gut permeability following the 7‐day HA protocol. Reductions in gut permeability were associated with increased exercise HSP70 accumulation and attenuated exercise cytokine responses. This may be a potential mechanism by which HA confers protection against exertional heat illness.
A claudin‐4 modulator enhances the mucosal absorption of peptide
Authors: Uchida Hiroshi , Kondoh Masuo , Hanada Takeshi , Takahashi Azusa , Hamakubo Takao , Yagi Kiyohito 
Published: June 2021

ObjectiveParacellular pathway is a principal route for absorption of biologics (peptides, proteins and nucleic acids); however, tight junctions (TJs) restrict passing of biologics across epithelium. Claudin is known as a key component in TJs‐barrier. We previously found that a claudin‐4 modulator, C‐terminal fragment of Clostridium perfringens enterotoxin (C‐CPE), enhanced jejunal absorption of dextran. In this study, we investigated whether a claudin‐4 modulator is a potent mucosal absorption‐enhancer of a peptide drug.MethodsMucosal absorption was evaluated by rat jejunal, pulmonary and nasal administration of human parathyroid hormone derivative, hPTH(1–34) and C‐CPEs. Plasma hPTH(1–34) levels were measured by RIA. Binding of C‐CPEs to claudin‐4 was assayed by ELISA and BIAcore analysis.ResultsPre‐treatment with C‐CPE enhanced mucosal absorption of hPTH(1–34). However, the jejunal and pulmonary absorption‐enhancing effects were not observed by co‐treatment with C‐CPE. The deletion of 10 amino acids at the N‐terminal of C‐CPE increased its solubility by 30‐fold. Moreover, the truncated C‐CPE bound to claudin‐4, modulated the TJ‐barrier and enhanced jejunal absorption of dextran. Co‐treatment of the truncated C‐CPE also enhanced jejunal and pulmonary absorption of hPTH(1–34).ConclusionClaudin‐4 modulator may be a promising absorption‐enhancer of a peptide drug.
Cortistatin Inhibits Intestinal Secretion in the Guinea‐pig Ileum In Vitro
Authors: Liu Sumei 
Published: June 2021

Background and AimsCortistatin (CST) is a novel neuropeptide with high structural homology with somatostatin. We previously found that CST is expressed by enteric neurons and acts as an inhibitory neurotransmitter in the submucosal plexus. The aim of the present study was to evaluate the effect of CST on neurogenic intestinal secretion.MethodsSubmucosal/mucosal preparations from guinea pig ileum were mounted in Ussing flux chambers for measurement of short‐circuit current (Isc) as an indicator of mucosal secretion. Transmural electrical field stimulation (EFS) was used to evoke neural‐mediated intestinal secretion.ResultsApplication of CST‐14 (rat), CST‐17 (human), CST‐29 (rat), or CST‐29 (human) to the submucosal side of the preparation decreased baseline Isc in a concentration‐dependent manner with an IC50 (in nM) of 90.5, 52.1, 102.9 or 71.6, respectively. The somatostatin‐2 receptor (SSTR‐2) antagonist CYN 154806 significantly suppressed CST‐14r, CST‐17h, CST‐29r, or CST‐29h‐evoked ΔIsc. The neuronal blocker tetrodotoxin significantly reduced CST‐14r, CST‐17h, CST‐29r, or CST‐29h‐evoked ΔIsc. CSTs produced a concentration‐dependent reduction of the EFS‐evoked secretory responses, which was antagonized by CYN 154806. Immunoreactivity (IR) of CST‐17 was found in submucosal neurons. CST‐17‐IR was localized in cholinergic secretomotor neurons but was absent from non‐cholinergic secretomotor neurons.ConclusionsThe results suggest that CSTs act at SST‐2 receptors in the submucosal plexus to suppress secretomotor neuronal excitability and neurogenic intestinal secretion.
Effects of nitric oxide on HIF‐1α and FIH‐1 following Clostridium difficile toxin exposure
Authors: Lee Joshua Youngun , Hirota Simon , Traboulsi Danya , Beck Paul , MacDonald Justin 
Published: June 2021

Clostridium difficile (C.diff) is a leading cause of infectious colitis in humans. C.diff toxins disrupt the intestinal epithelial barrier and induce the release of proinflammatory mediators. The hypoxia‐inducible factor‐1 (HIF‐1α) is a stress‐induced transcription factor that mediates mucosal and barrier protective genes. Nitric oxide (NO) and the factor‐inhibiting HIF‐1α (FIH‐1) modulate HIF‐1α expression and signaling, respectively. We hypothesize that NO produced during C.diff toxin‐induced intestinal injury is an important signal to activate HIF‐1α‐mediated protection against C.diff toxin‐induced damage.The in vitro studies analyzed HIF‐1α and FIH‐1 levels during toxin exposure of Caco2 cells. Cells were challenged with both toxin and nitric oxide synthase (NOS) inhibitors to study NO effects on HIF‐1α/FIH‐1 expression. In vivo studies assessed ileal loop tissue from toxin‐treated wild‐type (WT) and inducible NOS knockout (iNOS KO) mice.We have identified that HIF‐1α levels increase at least two‐fold in toxin‐treated cells. FIH‐1 levels also show a 35% decrease in response to toxin. This increase in HIF‐1α protein was suppressed with NOS inhibition. In vivo, serum NO levels increased with toxin exposure; a response which was abrogated in iNOS KO mice.Further study is needed to demonstrate a direct effect of NO on HIF‐1α levels in response to C.diff toxin in vivo. Funding provided by CAG and CIHR.
Molecular Identification and Quantitative Analysis of Voltage‐gated K+ Channels of Rat Hypothalamic Paraventricular Nucleus Neurons
Authors: LEE SEUL KI , LEE SORA , SHIN SEUNG YUB , RYU PAN DONG , LEE SO YEONG 
Published: June 2021

The hypothalamic paraventricular nucleus (PVN), an important integrating site in regulating the neuroendocrine and autonomic nervous systems, is composed of heterogeneous neurons. These neurons are classified into two groups, type I and type II neurons, based on their electrophysiological properties. In the present study, we investigated the molecular identification of voltage‐gated K (Kv) channels. These are known to be associated with a delay in the onset of the first action potential, which is a distinctive characteristic of type I neurons.In order to identify the mRNA expression profiles, the PVN neurons were divided into type I and type II neurons according to their electrophysiological properties. The recorded cells were harvested and single‐cell RT‐PCR analysis was performed. The single‐cell RT‐PCR analysis revealed that Kv1.2, Kv1.3, Kv1.4, Kv4.1, Kv4.2, and Kv4.3 were expressed in both type I and type II neurons. The relative quantitative analysis revealed that the expression density of Kv1.2, Kv4.2, and Kv4.3 were significantly higher in type I neurons than in type II neurons. These results suggest that several Kv channels are present in both type I and type II neurons and Kv1.2, Kv4.2 and Kv4.3 are the potential Kv channels responsible for determining the distinct electrophysiological properties. This work is supported by National Research Foundation of Korea (2009‐0067186)
Lesion of the organum vasculosum of the lamina terminalis (OVLT) does not impair the hypotension produced by chronic infusion of losartan in conscious rats
Authors: Vieira Alexandre Antonio , Nahey David , Collister John 
Published: June 2021

IntroductionSeveral forebrain areas possess important mechanisms related to cardiovascular regulation including those mediating effects of angiotensin II (ANG II). We have previously demonstrated in conscious rats that lesions of the OVLT completely blocked the hypertension produced by chronic infusion of ANG II.AIMIn the present study we tested the hypothesis that the OVLT is also necessary for the hypotension produced by chronic infusion of AT1 antagonist losartan.MethodsSham or OVLT Sprague‐Dawley lesioned rats (280–320 g, n=5/group) were instrumented with intravenous catheters and radiotelemetric blood pressure transducers. Rats were given 3 days of saline control infusion (7 mL/day) and were then infused with losartan (10 mg/kg/day) for 10 days, followed by 3 recovery days. Twenty‐four (24‐hour) average measurements of mean arterial pressure (MAP) and heart rate (HR) were made throughout the protocol. Daily water and food intake, as well as urinary output (UO) were measured.ResultsBy day 8 of losartan infusion, MAP had decreased similarly (35 ± 3 mmHg) in sham rats and (39 ± 3 mmHg) in OVLT lesioned rats, without changes in HR. Moreover, OVLT lesions did not produce any changes in water and food intake and also in UO.Conclusion and discussionThe integrity of the OVLT is not important for the hypotension produced by infusion of losartan in conscious rats. These results suggest that the OVLT might play an important role during elevation of plasma ANG II facilitating increases of blood pressure but is not involved with baseline effects of endogenous ANG II.Support: Capes Foundation/Brazil, process number: BEX 1819/09‐7
Bradykinin B2 receptor activates extracellular signal regulated kinase in renal cells from a mouse model of polycystic kidney disease
Authors: Bunni Marlene A , Morinelli Thomas A , Bell Phillip D , Raymond John R , Garnovskaya Maria N 
Published: June 2021

The vasoactive peptide bradykinin (BK) is a mitogen for normal renal cells. We explored the effects of BK in orpk cilia (+) and orpk cilia (−) collecting duct cell lines, which were derived from a mouse model of polycystic kidney disease (PKD). mRNAs for BK B1 and BK B2 receptors were demonstrated by RT‐PCR in both cell lines. To study BK signaling pathways, we employed fluorescent measurements of intracellular Ca2+, a Cytosensor microphysiometer to measure changes in extracellular pH as a reflection of activation of the Na+/H+ exchanger (NHE), and Western blotting to assess extracellular signal regulated kinase (ERK) activation.Exposure to 100 nM BK resulted in rapid elevation of intracellular Ca2+, caused a ≥ 20% increase in NHE activity, and a ≥ 200% increase in ERK phosphorylation. While BK‐induced Ca2+ signals and NHE activation were similar in orpk cilia (+) and orpk cilia (−) cell lines, BK‐induced ERK phosphorylation was less pronounced in orpk cilia (−) cells. The BK B2 receptor antagonist and an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor blocked BK‐induced ERK phosphorylation suggesting a role for the B2 receptor‐induced EGFR transactivation in the mitogenic ERK pathway. We speculate that cilium is required for effective transactivation of EGFR and ERK activation by BK B2 receptors in PKD cells. These studies are important because of proposed role of ERK pathway in pathophysiology of PKD.
Higher renal AT1 receptor affinity exaggerates Ang II induced Na/K‐ATPase stimulation in spontaneously hypertensive rats.
Authors: Javkhedkar Apurva Arvind , Lokhandwala Mustafa F , Banday Anees Ahmad 
Published: June 2021

Angiotensin II (Ang II) via renal Ang II type 1 receptors (AT1 R) regulates proximal tubular Na reabsorption by acting on Na/K‐ATPase (NKA) and thus plays an important role in regulation of blood pressure (BP). Recent evidences suggest that oxidative stress modulates the function of renal AT1 R during hypertension. The aim of the present study is to investigate if oxidative stress modulates renal AT1 R signaling in spontaneously hypertensive rats (SHR). We performed experiments in 12 weeks old SHR and Wistar Kyoto (WKY) rats served as control. Our results show that in addition to increased BP there is oxidative stress in proximal tubules, as evidenced by increase in protein carbonylation, in SHR compared to WKY rats. Western blot analysis showed equal AT1 R protein expression in SHR and WKY rats. 125I‐sar‐ANG II binding showed an increase in affinity of AT1 R in SHR, but no change in receptor numbers. In SHR there was enhanced AT1R‐ G protein‐coupling and stimulation of protein kinase C activity. In WKY rats, incubation of proximal tubules with Ang II caused stimulation of NKA at low (10−10M) concentration but not at high (10−6M) concentration. However in SHR we observed stimulation of NKA at both concentrations of Ang II.These data suggest that in SHR oxidative stress is associated with increased renal AT1 R affinity which leads to enhanced Ang II signaling resulting in greater NKA stimulation which contributes to hypertension.
Novel adaptations of the pinniped (Mammalia:Carnivora) jaw anatomy to aquatic prey‐capture
Authors: Jones Katrina Elizabeth , Ruff Chris , Goswami Anjali 
Published: June 2021

Biomechanical models of jaw anatomy in terrestrial mammals often focus on mastication as the driving force for adaptation. As marine mammals, pinnipeds (e.g.seals) use their jaws primarily for prey‐capture; but not for mastication. Here we reveal the functional adaptations of jaw anatomy to novel marine feeding behavior; filter feeding, suction feeding and “grip and tear” feeding.We measured 100 mandibles, representing 25 of 34 extant species, using a digitizer to capture co‐ordinate data for 15 homologous landmarks. Relevant linear measurements were extracted from the landmark data. We then used X‐ray data to reconstruct cortical thickness to calculate section modulus (strength estimate) for four species (n=25). We compared the specialist feeders for each measure, based on expected mechanical scaling.Filter feeders displayed a very long toothrow, which increases sieve area, and a highly elliptical mandibular symphysis to prevent wishboning during the expulsion of water. The suction feeding jaw was shorter with a weaker mandible, lower bite force and diminutive canines, due to the reduced requirement for biting. Grip and tear feeders were adapted for a large gape (longer jaw), strong biting, and a posteriorly directed muscle vector for capturing large prey. This study elucidates novel adaptation of mammal jaw anatomy to the biomechanical challenges of prey‐capture in the marine realm.
Lectin‐dependent quality control of the Na,K‐ATPase maturation in the ER
Authors: Vagin Olga , Tokhtaeva Elmira , Munson Keith , Sachs George 
Published: June 2021

To evaluate the role of N‐glycan‐lectin interactions in maturation of the Na,K‐ATPase β2 subunit, the effects of removing all 8 or selected N‐glycans on trafficking of the β2 and its binding to calnexin were studied in MDCK cells. N‐glycan‐dependent binding of the β2 to calnexin persists for several hours after completing translation, suggesting involvement of the ER glucosyltransferase UGGT1 that is known to induce additional rounds of calnexin‐assisted folding of misfolded glycoproteins by re‐glucosylating N‐glycans next to local folding defects exposing hydrophobic amino acids. The β2 is retained in the ER when calnexin binding is prevented by castanospermine. Homology modeling of the β2 using the crystal structure of the α1‐β1 Na,K‐ATPase shows the presence of a relatively hydrophobic cluster proximal to N‐glycans 2 and 7. Combined, but not separate, removal of N‐glycosylation sites 2 and 7 dramatically impairs calnexin binding and prevents the export of the β2 from the ER. Similar effects are observed with hydrophilic substitution of two hydrophobic amino acids in the cluster, suggesting that exposure of these residues in incompletely folded conformers results in UGGT1‐catalyzed re‐glucosylation of N‐glycans 7 and 2, allowing post‐translational calnexin‐assisted re‐folding, which, in turn, is required for maturation of the Na,K‐ATPase β2 subunit.Supported by NIH grants DK077149 and DK058333.