bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic hypoxia‐mediated oxidative stress downregulates the large‐conductance Ca2+‐activated K+ channel activity in uterine arteries in pregnancy (889.4)
Authors: Hu Xiang‐Qun , Zhang Lubo 
Published: June 2021

Chronic hypoxia during pregnancy constitutes a major insult to maternal cardiovascular homeostasis, leading to complicated uteroplacental circulation. We recently demonstrated that long term high‐altitude hypoxia enhanced uterine arterial myogenic tone, which was mediated by the downregulation of the large‐conductance Ca2+‐activated K+ channel (BKCa) activity via enhanced oxidative stress. In the present study we tested the hypothesis that chronic hypoxia exposure directly increases generation of reactive oxygen species (ROS) in the uterine artery from pregnant sheep, which in turn suppresses BKCa channel activity in VSMCs of the vessel. Uterine arteries were isolated from near‐term (~140 days) pregnant sheep and incubated under 21% or 10.5% O2 for 48 hours at 37 °C. Exposure to chronic hypoxia significantly increased ROS levels and depressed the BKCa current density (p < 0.05). Neither ROS levels nor BKCa current density in tissues cultured in 21% O2 were altered by the antioxidant N‐acetylcysteine (NAC). However, the increased ROS level and depressed BKCa current density during exposure to chronic hypoxia were ablated by NAC. Our findings suggest a direct effect of chronic hypoxia in suppressing the function of BKCa channels in uterine arteries through increased generation of ROS, which may contribute to the increased myogenic tone of uterine arteries in response to chronic hypoxia during gestation.Grant Funding Source: HL089012, HL110125
The antioxidant effects of thymoquinone in lipopolysaccharide‐activated BV2 murine microglia cells (89.5)
Authors: Duval Makini , Taka Equar , Mazzio Elizabeth , Soliman Karam 
Published: June 2021

Activation of microglia, resident immune cells in the central nervous system (CNS), is implicated in the pathogenesis and progression of neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease. They may cause a vicious self‐perpetuating neuronal degeneration cycle via excessive release of superoxide radicals in the system. We explored the effects of thymoquinone (TQ), the main active constituent of Nigella sativa seed oil, as an antioxidant agent in microglial activation. We hypothesized that the antioxidant properties of TQ are mediated in part by reducing proteins involved in oxidative stress induced by microglia activation. In this study, BV2 cells were stimulated with LPS in the presence or absence of TQ. To profile the effect of TQ on global protein expression of BV2 microglial cells, two‐dimensional (2D)‐gel electrophoresis with MALDI‐TOF/TOF (matrix‐assisted laser desorption/ionization ‐ time of flight) analysis was employed. Additionally, the effect of TQ on microglia activation was evaluated using immunocytochemistry‐ immunofluorescence (ICC‐IF). The results obtained indicate that TQ decreased the expression of 60 kDa heat shock, fatty acid binding, and CD68 [ED1] proteins in LPS stimulated BV2 cells. These findings suggest that the intervention of microglial activation process could be a promising therapeutic target in the treatment of a number of neurodegenerative conditions.Grant Funding Source: Supported by NIH grants: NIMHD G12 MD007582 and P20 MD006738
Patterning neuronal networks on photolithographically‐defined parylene:silicon substrates (89.6)
Authors: Hughes Mark , Brennan Paul , Bunting Andrew , Murray Alan , Shipton Mike 
Published: June 2021

Interfacing neurons with silicon can provide insights into neuronal coding and a basis for neuroprostheses. We aim to construct networks on parylene‐patterned SiO2, previously used to successfully pattern primary murine hippocampal cells. A key question is whether neurons will pattern in isolation, or whether they require a supporting cellular template. Both undifferentiated (UD) and differentiated (DF) Lund Human Mesencephalic (LUHMES) neurons fail to adhere, nor show morphological signs of differentiation, when cultured alone on‐chip (UD LUHMES parylene adhesion index (PAI) 0.02±0.05, silicon repulsion index (SRI) 1.0±0.01; DF LUHMES PAI 0.0±0.0,SRI 1±0.001). We therefore sought a different cell type to pre‐pattern on parylene. HEK 293 cells patterned accurately (PAI 0.46±0.2,SRI 0.98±0.01) as did a human glioma‐derived cell line (PAI 0.96±0.01,SRI 0.95±0.01). LUHMES, plated secondarily, adhered specifically to either cellular template, extending neurites to form a network. The next challenge is to control network topography. By altering the configuration of an array of parylene nodes, we have generated orthogonal networks. Hypothesizing that parylene can haptotactically guide neurites, different nodular features (teardrop shapes or short tracks) were created. Neurite directionality was not influenced by parylene shape; neurites instead connected with the nearest adjacent cell cluster.Grant Funding Source: Wellcome Trust
Electrical stimulation enhances functional recovery after sciatic nerve injury (89.7)
Authors: Meadows Rena , McMillan Kate , Batka Richard , Brown Todd , Sengelaub Dale , Jones Kathryn 
Published: June 2021

Direct injury to the sciatic nerve is a major clinical problem facing surgeons, as it leads to loss of limb function and devastation to a patient’s quality of life. Presently, no non‐surgical treatment strategies are clinically used to treat peripheral nerve injury (PNI). Recent work has shown testosterone propionate (TP) and electrical stimulation (ES) enhance functional recovery after injury to the facial nerve. Since lower limb nerve injuries following trauma comprise a significant portion of PNI, we hypothesized the combinatorial treatment of ES and TP improved axonal regeneration after injury to the sciatic nerve. We utilized several behavioral tests, such as grip strength, unforced gait analysis, and foot misplacement, to test this hypothesis. After a two week training period, animals received a crush injury to the right sciatic nerve. Following injury, animals received either no treatment or treatment with ES and/or TP. After treatment, animals were subjected to behavioral testing for 8 weeks to assess functional recovery. Results indicated ES accelerated grip strength recovery and improved several gait parameters compared to no treatment, whereas TP and ES + TP were not different from control. These data indicate location and type of nerve injury could guide strategies for clinical treatment.Grant Funding Source: Supported by the Veterans Affairs
Contribution of hemodilution to renal hypoxia following cardiopulmonary bypass surgery (890.12)
Authors: Sgouralis Ioannis , Evans Roger , Gardiner Bruce , Layton Anita 
Published: June 2021

Acute kidney injury (AKI) is a prevalent complication of surgical procedures that require cardiopulmonary bypass (CPB). We have used a mathematical model of the rat kidney to simulate renal hemodynamics during CPB and to study the pathways that can lead to AKI. The model represents vascular blood flow, glomerular filtration, and metabolically driven salt reabsorption along the nephron. Autoregulation is provided by active afferent arteriole constriction initiated by the myogenic response and tubuloglomerular feedback. The model simulates the effects of (i) reduced renal perfusion pressure, which reduces blood flow and glomerular filtration rate (GFR); (ii) hemodilution, which increases GFR; and (iii) hypothermia, which reduces sodium reabsorption and oxygen consumption. Medullary oxygenation is determined by the balance between oxygen consumption, which is increased by hemodilution but decreased due to low perfusion pressure and temperature, and medullary blood supply, which is reduced by hemodilution and the low perfusion pressure. Model simulations suggest that the rise in body temperature following the surgery increases medullary oxygen consumption and drives the kidney into a hypoxic state which may result in AKI. This research was supported in part by NIH grant DK‐89066.Grant Funding Source: NIH DK089066
Contralateral nephrectomy‐induced improvement in renal structure and function following unilateral ischemia‐reperfusion injury is counter intuitively associated with markers of renal hypoxia (890.5)
Authors: Polichnowski Aaron , Licea‐Vargas Hector , Lan Rongpei , Picken Maria , Long Jianrui , Williamson Geoffrey , Rosenberger Christian , Griffin Karen , Venkatachalam Manjeri , Bidani Anil 
Published: June 2021

Unilateral ischemia‐reperfusion injury (UIRI) leads to progressive renal atrophy and tubulointerstitial fibrosis (TIF). However, contralateral nephrectomy (CNX) 2 wks post UIRI can improve renal function and reverse TIF via poorly defined mechanisms. We examined the renal hemodynamic, structural and hypoxia signaling correlates associated with UIRI and its reversal by CNX. Two wks after 60 min UIRI or sham UIRI, BP (radiotelemetry), left RBF (Transonic) and 24 hr GFR measurements (FITC‐inulin, osmotic minipumps) were made in conscious rats and then repeated every 2‐3 days for 2 wks following CNX or sham CNX. In the presence of a contralateral uninjured kidney, RBF (ml/min) was reduced (P<0.05) in UIRI (4.1±0.4) vs. sham UIRI (9.3±0.8) kidneys. Without CNX, extensive renal atrophy, TIF, and tubule dedifferentiation, but minimal pimonidazole and HIF‐1α positivity, were present at 4 wks post UIRI. Conversely, CNX increased (P<0.05) GFR (ml/min) from 0.8±0.1 to 1.3±0.1 over 2 wks and led to sustained increases (P<0.05) in RBF (6.2±0.6 ml/min). CNX‐induced improvement in renal function was associated with renal hypertrophy, more redifferentiated tubules, less TIF and robust pimonidazole and HIF‐1α staining in UIRI kidneys. We conclude that TIF at 4 wks post UIRI without CNX is not associated with indices of hypoxia, which, unexpectedly correlated with recovery of renal function/structure and reversal of TIF following CNX.Grant Funding Source: Supported by Veterans Administration, National Institute of Health, National Kidney Foundation of IL
Renal hypoxia due to increased oxygen metabolism is an independent pathway to nephropathy (890.6)
Authors: Friederich‐Persson Malou , Persson Patrik , Fasching Angelica , Hansell Peter , Nangaku Masaomi , Palm Fredrik 
Published: June 2021

The proposed pathways for the development of nephropathy are many and likely to be complex and overlapping. Recent literature strongly supports a role of renal tissue hypoxia as a pathway to nephropathy but the evidence remains inconclusive as the role of hypoxia cannot be separated from confounding factors such as hyperglycemia, hypertension and oxidative stress. By increasing kidney oxygen consumption (QO2) using triodothyronine (T3) we aimed to investigate the role of renal hypoxia per se for the development of nephropathy.Normoglycemic Sprague‐Dawley rats were treated with T3 (10 mg/kg bw/day) for 56 days. Thereafter, glomerular filtration rate (GFR), renal blood flow (RBF), total kidney QO2, kidney oxygen tension (pO2, Clark‐type oxygen electrodes) proteinuria, oxidative stress and histological alterations were evaluated and compared to corresponding controls.T3 increased kidney QO2 (18±2 vs. 11±1 µmol/min/kidney, p<0.05) and decreased kidney pO2 (27±1 vs. 44±1 mmHg, p<0.05). Furthermore, T3 resulted in proteinuria (74±6 vs. 54±5 µg/min/kidney, p<0.05) and four of eight T3‐treated rats, but none of the controls, presented with focal tubulointerstitial fibrosis. GFR (1.4±0.2 vs. 1.5±0.2 ml/min), RBF (12.7±1.6 vs. 11.1±0.8 ml/min), TBARS (15±2 vs. 16±3 fmol/min/kidney) and blood glucose (4.8±0.2 vs. 5.1±0.2 mM) were unaffected by T3. The detected mitochondrial uncoupling and increased ATP synthesis provide a mechanistic explanation for the increased kidney QO2.In conclusion, the present study adds further evidence in support of renal tissue hypoxia as an independent pathway to nephropathy.
Increased renal oxygen consumption leads to hypoxia in sepsis‐associated acute kidney injury (890.9)
Authors: Singh Prabhleen , Ayoyama Koji , Nourbakhsh Noureddin , Thomas Joanna 
Published: June 2021

We have shown in subtotal nephrectomy (STN), a model of chronic kidney disease, there is increased oxygen consumption (QO2) factored for tubular Na reabsorption (TNa) leading to hypoxia. To demonstrate the universality of hypoxia in the pathogenesis of kidney disease, we have now examined renal oxygenation (oxygen delivery and consumption), mitochondrial function and tubular transport in acute kidney injury (AKI) due to sepsis in a rat model of cecal ligation and puncture (CLP). Data presented as mean±sem.At 6 and 24 hours, GFR was significantly lower in CLP (2.5±0.4 vs. 3.6±0.2 ml/min and 1.2±0.3 vs. 3.3±0.2 ml/min, p<0.001). While RBF and O2 delivery was largely unchanged, renal O2 extraction and QO2 factored for GFR was higher compared to shams, (0.023±0.002 vs. 0.01±0.001 vol%ml/min and 0.11±0.01 vs. 0.05±0.01 ml/min,p<0.04). HIF‐1a expression was upregulated in the CLP kidneys at both 6 and 24 hours. In CLP, we found elevated rates of mitochondrial QO2 (199.9 ± 31.6 pMol/min vs. 163.2 ± 28.81 pMol/min, p<0.05), but significantly lower ATP generation with reduced expression of complex Va and complex III (p<0.05 for both). Proteins regulating mitochondrial morphology were also altered with increased expression of fission protein DRP1 (P<.0004) and decreased expression of PGC‐1alpha, a factor in mitochondrial biogenesis (2.2‐fold lower) in CLP. HIF‐1α activation by DMOG improved GFR at both time points.We demonstrate increased renal QO2 despite lower GFR leading to hypoxia and dissociation between excess QO2 and ATP generation in CLP mitochondria. We are investigating alterations in mitochondrial dynamics which could explain mitochondrial dysfunction and tubular injury, and the role of HIF‐1α pathway in this. In conclusion, our data in both acute and chronic kidney injury model demonstrates early hypoxia due to increased oxygen consumption leading to oxygen demand‐supply mismatch and strongly supports the role of hypoxia as a unifying mechanism for kidney disease.Grant Funding Source: NIH
Mathematical model of ammonia handling in the rat renal medulla (891.3)
Authors: Noiret Lorette , Thomas S. Randall 
Published: June 2021

Ammonia produced in the kidney can be absorbed into the renal vein or excreted in urine. We developed a mathematical model of the rat renal medulla in order to identify some of the components controlling the fate of renal ammonia. The model simulates the movements of water, sodium, urea, NH3, NH4+ and a non‐reabsorbable solute along nephrons and vasa recta of various lengths and includes pH, potassium concentrations, and electrical potential as imposed boundary conditions at each medullary depth. A sensitivity analysis was performed to identify the transport parameters and micro‐environmental conditions that have the greatest effect on the simulated rate of urinary ammonia excretion. Our results suggest that urinary ammonia excretion is mainly controlled by the parameters that affect ammonia delivery to the descending segment of short nephron. In particular, interstitial pH in the outer medulla seems to be critical. The model provides the first coordinated picture of renal ammonia handling.Grant Funding Source: Supported by the EPSRC through the UCL CoMPLEX doctoral training centre (UK).
Prostaglandin E2 EP3 receptor regulates the diuretic response to hypertonic stress (892.38)
Authors: Hao Shoujin , Vio Carlos , Quiroz‐Munoz Mariana , Cespedes Carlos , Hao Hao , Ferreri Nicholas 
Published: June 2021

We recently showed that activation of prostaglandin E2 (PGE2) EP3 receptors during normal sodium intake is part of a negative feedback mechanism that attenuates cyclooxygenase‐2 (COX‐2) expression in the thick ascending limb (TAL). However, the functional effects of this mechanism have not been determined. Since PGE2 exhibits natriuretic and diuretic functions, we determined the consequences of EP3 receptor manipulation and its relationship to COX‐2 expression and activity in response to hypertonic saline stress. EP3 receptor expression in the outer medulla increased about 2‐fold in Sprague‐Dawley rats given free access to 1% NaCl in the drinking water for 7 days compared with tap water; p<0.05. Ingestion of 1% NaCl also increased COX‐2 mRNA accumulation and protein expression in freshly isolated mTAL tubules, an effect that was augmented when EP3 was blocked. Urine volume increased approximately 2.5‐fold during ingestion of 1% NaCl but was reduced by ~40% on days 1‐7 in rats pretreated with a EP3 receptor agonist (sulprostone: 20 μg·kg−1·day−1) for 3 days. The decrease in urine volume was associated with a decline in COX‐2‐dependent PGE2 synthesis. In contrast, the increase in urine volume induced by 1% NaCl intake was significantly augmented after pretreatment with a selective EP3 receptor antagonist (L‐798106: 100 μg·kg−1·day−1) and was associated with an increase in PGE2 synthesis. Collectively, the data suggest that the COX‐2/PGE2 signaling pathway involving EP3 underlies the diuretic response to increased NaCl intake. The mechanism that contributes to these effects is currently under investigation.Grant Funding Source: NIH HL34300, American Heart Association 12GRNT12060350, Fondecyt 1130741, PGB12‐2007 CARE UC‐SQM
Regulation of calcium reabsorption in the rat kidney (892.4)
Authors: Edwards Aurelie , Ramakrishnan Suresh , Houillier Pascal 
Published: June 2021

We have developed a mathematical model of calcium (Ca2+) transport from the thick ascending limb to the inner medullary collecting duct (IMCD) to investigate the factors that promote hypercalciuria, one of the main risk factors for kidney stone formation. Calcium is reabsorbed passively in the thick ascending limb, and actively in the distal convoluted (DCT) and connecting (CNT) tubules. The model represents the detailed epithelial transport of Ca2+ and other solutes in these segments; it accounts for the specific apical and basolateral transporters of each cell type. Model simulations reproduce experimentally observed variations in urinary Ca2+ excretion following treatment by furosemide or Ca2+ transporter inhibition. The model predicts complex interactions between the reabsorption of Ca2+ and that of other solutes in the nephron. Our results also suggest that the DCT and CNT barely adapt to upstream variations in Ca2+ transport. In contrast, regulation of the IMCD water permeability by calcium sensing mechanisms is predicted to significantly mitigate the effects of high Ca2+ loads in the distal nephron.Grant Funding Source: Supported by the Agence Nationale de la Recherche (France)
Elucidating the role of a renal proximal tubule‐specific olfactory receptor (892.42)
Authors: Shepard Blythe , Cheval Lydie , Doucet Alain , Pluznick Jennifer 
Published: June 2021

Olfactory receptors (ORs) are seven transmembrane domain G protein‐coupled chemosensors that detect odorants in the nose. We previously reported that OR signaling plays a role in the kidney (PNAS 2009), and to date we have identified 9 renal ORs. One of these is Olfr1393, which is widely expressed in a number of tissues, including kidney (by RT‐PCR screen). Using reverse‐transcribed RNA from microdissected renal segments, we found that Olfr1393 is exclusively expressed in the proximal tubule (PT; S1, S2 and S3). Like the majority of ORs, Olfr1393 is an orphan receptor with no known ligand. To screen for ligands, we cloned this receptor from the kidney and expressed it in HEK293T cells after optimizing conditions to allow for surface expression. We comprehensively screened over 1400 chemicals, and found that Olfr1393 detects preconstrained cyclic molecules containing either a carbonyl or alcohol group. We also found that when stably expressed in polarized MDCK cells, Olfr1393 localizes to the apical PM yet is excluded from the primary cilia. To determine the function of this receptor, we generated knockout (KO) mice. At baseline, KO mice appear to be in homeostatic balance based on plasma electrolytes, BUN, creatinine, urinalysis, and blood pressure measurements ‐ in future studies, we will challenge WT and KO mice with Olfr1393 ligands to ascertain how PT and renal function are regulated by Olfr1393.Grant Funding Source: Supported by: NIDDK and ASN
Flow stimulated apical endocytosis in renal proximal tubule epithelia (892.6)
Authors: Raghavan Venkatesan , Rbaibi Youssef , Pastor‐Soler Nuria , Carattino Marcelo , Weisz Ora 
Published: June 2021

The kidney is able to maintain solute and fluid reabsorption over a wide range of GFRs. Internalization of filtered low molecular weight proteins, vitamins, hormones, and other small molecules is mediated by the proximal tubule (PT) multiligand receptors megalin and cubilin. Microvillar bending in response to increases in GFR and the accompanying fluid shear stress (FSS) modulates PT ion transport capacity. However, whether FSS affects endocytosis in PT cells is unknown. Exposure of rat kidney slices to FSS led to a dramatically increased internalization of the megalin/cubilin ligand albumin and the fluid phase marker dextran in cortical tubules. Similar results were observed when PT cell lines were subjected to physiologically relevant levels of FSS. Flow stimulated endocytosis was initiated by 15‐30 min post induction of FSS, was clathrin‐ and dynamin‐dependent, and was rapidly reversed. FSS also caused a rapid elevation in intracellular Ca2+ levels, which was not observed in deciliated cells or upon inclusion of apyrase in the medium. Strikingly, deciliation and apyrase treatment also blocked the flow dependent increase in endocytosis. We hypothesize that changes in intracellular Ca2+ in response to flow‐dependent ciliary bending triggers the observed increase in PT apical endocytosis via a mechanism that involves extracellular ATP‐dependent calcium release from intracellular stores.Grant Funding Source: Supported in part by the Lowe Syndrome Association
Statins increase AQP2 urinary excretion in hypercholesterolemic patients: a pleiotropic effect of statins of potential interest for patients with defects of AQP2 trafficking. (892.8)
Authors: Procino Giuseppe , Mastrofrancesco Lisa , Bonfrate Leonilde , Castorani Luigi , Milano Serena , Nicoletti Maria , Carmosino Monica , Portincasa Piero , Svelto Maria 
Published: June 2021

We reported that statins treatment increases AQP2 membrane expression in both cultured renal cells and in the renal tubule of mouse, but the ultimate effect in human kidney is unknown. Here, we conducted a pilot clinical study on AQP2 membrane expression in hypercholesterolemic patients requiring statin therapy. In humans, urinary AQP2 (uAQP2) is a non‐invasive, reliable biomarker correlating with the amount of plasma membrane‐expressed AQP2.Nineteen naïve patients with sustained hypercholesterolemia were enrolled along with 15 patients already under statin treatment for at least 1 year. We quantified the 24 h uAQP by ELISA. First, uAQP2 levels were compared in the two groups of patients. Then, time‐dependent changes of uAQP2 levels were studied at baseline, week1 and week 2 in naïve patients starting statin treatment (simvastatin 10‐20 mg/day).uAQP2 was significantly higher in patients chronically treated with statins compared to naïve (3839±319 pmol/24 h vs. 2819±234 pmol/24 h).Following statins treatment in naïve patients, uAQP2 shifted from 2471±358 pmol/24 h at baseline to 4443±493 pmol/24 h, at the end of the week1, and to 4003±450 pmol/24 h at the end of week2 of treatment.We conclude that the pleiotropic effect of statins on AQP2 plasma membrane abundance is attainable in humans at pharmacological doses. This finding has considerable relevance for those pathological conditions in which AQP2 membrane trafficking is impaired as in nephrogenic diabetes insipidus.Grant Funding Source: Telethon GGP12040/ AIFA MRAR08P011