bluuebunny/crossref_metadata_2025_split huggingface dataset:
Knockout of Na‐glucose transporter SGLT1 lowers GFR and kidney weight in non‐diabetic and Akita diabetic mice
Authors: Song Panai , Fu Yiling , Onishi Akira , Qiu Hongyu , Koepsell Hermann , Vallon Volker 
Published: November 2023

BackgroundRenal SGLT1 reabsorbs 3% of filtered glucose in euglycemia. Diabetes strongly increases the absolute renal glucose reabsorption by SGLT1. To gain more insights on the functional consequences of SGLT1 inhibition in diabetes, we determined the renal effects of genetic deletion of SGLT1 in Akita mice, a model of type 1 diabetes mellitus.MethodsSGLT1‐KO mice (C57BL/6J) were backcrossed to DBA2 background for at least 4 generations and crossed with heterozygous Ins2Akita mice, a genetic model of type 1 diabetes, to generate 4 experimental groups; i) WT, ii) SGLT1‐KO, iii) diabetic WT, and iv) diabetic SGLT1‐KO (n=10–21/group). All mice were fed low‐glucose high‐protein diet to prevent diarrhea in SGLT1‐KO. Systolic blood pressure (SBP) was measured by automated tail cuff, and glomerular filtration rate (GFR) by plasma elimination kinetics of FITC‐sinistrin at 20–23 weeks of age, both in conscious mice.ResultsIn non‐diabetic mice, SGLT1‐KO increased urine glucose/creatinine ratios vs WT (186±31 vs 9±1 μmol/mg; P<0.01), associated with similar body weight (31±1 vs 30±1 g), blood glucose (114±5 vs 114±5 mg/dl), and SBP (116±1 vs 116±2 mmHg), whereas GFR and kidney weight were modestly reduced (23.6±1.2 vs 28.5±1.5 μl/min/g ; 9.1±0.3 vs 10.2±0.1 mg/g; each P<0.05 ). In SGLT1‐KO and WT, diabetes increased blood and urine glucose and SBP to similar levels (314±21 vs 324±30 mg/dl; 2165±758 vs 2491±872 μmol/mg creatinine; 127±2 vs 128±2 mmHg), increased food and fluid intake (not shown) and decreased body weight (28±1 vs 28±1 g). Diabetes increased GFR and was associated with a small increase in kidney to body weight ratios; this occurred to a similar extent in SGLT1‐KO and WT, such that GFR (28.3±3.7 vs 35.1±2.3 μl/min/g, P<0.05) and kidney weight (10.1±0.2 vs 11.1±0.4 mg/g; P<0.05) remained lower in diabetic SGLT1‐KO vs WT.Conclusion1) In the absence of diabetes, SGLT1‐KO increased urine glucose and modestly reduced GFR and KW without affecting blood glucose and SBP. 2) The diabetes‐induced increase in blood glucose levels, SBP, GFR or kidney to body weight ratios was independent of SGLT1. 3) In the diabetic state, SGLT1‐KO mice maintained lower GFR and kidney to body weight ratios compared with WT mice.Support or Funding InformationNational Institutes of Health (R01DK56248, P30DK079337)
Regulation of 24p3 Receptor (24p3R/SLC22A17) Expression by Tonicity in Rodent Renal Inner Medullary Collecting Duct (IMCD) Cells
Authors: Thevenod Frank , Langelueddecke Christian , Probst Stephanie , Scharner Bettina , Betten Richard , Mese Kemal , Edemir Bayram 
Published: November 2023

Background and AimsThe 24p3/NGAL/lipocalin‐2 receptor (24p3R/SLC22A17) is apically expressed in rodent collecting ducts, including IMCD, where it may mediate protein endocytosis (Langelueddecke C. et al. J. Biol. Chem. 287:159–169, 2012) and induce pro‐inflammatory and pro‐fibrotic signalling in response to albuminuria (Dizin E. et al. Am. J. Physiol. Renal Physiol. 305:F1053‐F1063, 2013). Cells of the inner medulla are exposed in vivo to a hyperosmotic environment, which requires an adaptive response for survival. Interestingly, we have identified a putative TonEBP DNA consensus motif in the 24p3R promoter sequence. Here we investigated the expression of 24p3R in cultured IMCD cells that were exposed to increased osmolarity.MethodsCultured mouse IMCD cells (mIMCD3) and rat primary IMCD cells were cultured in 300 – 900 mOsm/kg for 1–6 days. Hypertonicity was induced by equimolar addition of NaCl + urea. 24p3R expression and localization were determined by qPCR, immunoblotting, surface biotinylation, flow cytometry and immunofluorescence microscopy.ResultsHypertonicity decreased cell proliferation and was accompanied by suppression of the cell proliferation genes c‐myc and cyclin‐D1 in mIMCD3 cells, which may reflect cellular stress and damage. Hypertonicity increased 24p3R mRNA and 24p3R protein expression and localization in plasma membranes of mIMCD3 and primary IMCD cells. Furthermore, plasma membrane localization of 24p3R was associated with increased dimerization of the protein.ConclusionsHyperosmotic environment decreases proliferation of IMCD cells but increases plasma membrane expression and dimerization of 24p3R, which may be mediated by TonEBP and contribute to adaptation of IMCD cells to osmotic stress.Support or Funding InformationFunded by DFG TH345/11‐1 and ZBAF
Glutathione (GSH) Absolute Synthesis Rates (ASR) of Multiple Organs in a Pseudomonas aeroginosa (PM) induced Hyperdynamic Sepsis Pig Model
Authors: Ten Have Gabriella A , Engelen Marielle P , Wolfe Robert R , Deutz Nicolaas E 
Published: November 2023

RationaleSepsis is characterized by a severe redox imbalance. GSH plays a major role in the cellular defense against oxidative and nitrosative stress. It remains unclear whether the GSH defense capacity of tissues is affected differently at an early stage of severe sepsis. Therefore we measured the early response in GSH synthesis of the gut, muscle, liver, and lung in an acute live bacteria (PM) induced hyperdynamic severe sepsis catheterized pig model.MethodWe studied GSH‐ASR in 13 pigs (±25 kg) with intravenous PM induced hyperdynamic sepsis and 9 healthy controls, using primed, constant and continuous infusion of Glycine (1‐13C) stable isotope in a conscious post‐absorptive state. Between 14 and 18 hours after start of the sepsis induction, we collected jejunal mucosa biopsies and erythrocytes, and at eighteen hours we obtained jejunum, jejunal mucosa scraping, ileum, liver, muscle and lung tissue. Enrichments of precursor pools and incorporated glycine in GSH were analyzed by LC‐MS/MS. Data are mean (SE) (in μmol/kg/h); ANOVA and unpaired t‐tests were done by GraphPad Prism.ResultsWe found decreased values for GSH‐ASR 14 to18h after sepsis induction in jejunal mucosa biopsies (p=0.032) but not in erythrocytes. At t=18 h, we found lower ASR in sepsis in jejunum (37.3 (5.5) vs 23.7 (2.6), p=0.021) and jejunal mucosa scrapings (45.0 (6.2) vs. 28.9 (3.9), p=0.033). No changes in GSH‐ASR in ileum, liver and muscle were found but GSH‐ASR tended to be higher in the lung (20.2 (3.0) vs 26.9 (2.2), p=0.086).ConclusionIn acute severe sepsis in the pig, the early defense capacity for oxidative stress is compromised in the mucosa of the jejunum, but not in the muscle, liver, lung, ileum and erythrocytes. We hypothesize that restoring the jejunal GSH defense capacity will attenuate the early sepsis induced gut dysfunction.Support or Funding InformationThis study was supported by NIH R01GM084447 and S10RR027047
Muscle Compression Causes Reduction of Oxidative Phosphorylation (OXPHOS) Subunits and Increase in Autophagy
Authors: Tam Bjorn T. , Yung Benjamin Y. , Wong Cesar S. , Chan Lawrence W. , Tam Eric W. , Siu Parco M. 
Published: November 2023

Pressure‐induced injury, skeletal muscle apoptosis and nitrosative stress can be induced in skeletal muscle by moderate mechanical compression in our established mouse model. Nonetheless, the effects of mechanical compression on oxidative phosphorylation (OXPHOS) subunits content and autophagic signalling in compressed skeletal muscle are largely unknown.PURPOSETo determine whether mechanical compression decreases the content of OXPHOS subunits and triggers autophagy in skeletal muscle.METHODSA single session of 4‐hour compression with static pressure of 150 mmHg was applied over the right lateral gastrocnemius muscle of mice. Tissues were harvested 48 hours after compression for analysis.RESULTSOur immunoblot data suggest that mechanical compression decreases OXPHOS subunits content. Furthermore, mechanical compression triggers autophagy in compressed skeletal muscle, resulting in increase in LC3‐II protein abundance and decrease in p62 protein abundance.CONCLUSIONThese results suggest that moderate mechanical compression leads to degradation of mitochondrial complexes which might impair the OXPHOS activity and, hence, the mitochondrial function. The degradation of mitochondrial complexes might possibly be induced by the upregulation of autophagy.Support or Funding InformationSupported by The Hong Kong Polytechnic University Research Funds (A‐PH69 and G‐U645) and General Research Fund (PolyU 5632/10M).
Coxiella burnetii Infection of Host Cells Involves PKC substrate MARCKS
Authors: Whitlock Sara , Funk Cornelius Joel 
Published: November 2023

The human disease Q‐fever is initiated as a respiratory tract infection by the bacterium Coxiella burnetii. Acute infections typically result in flu‐like symptoms and can be treated with antibiotics, but untreated chronic infections can lead to severe conditions including endocarditis. Bacteria enter alveolar macrophages within a phagosome, but instead of being destroyed by cellular enzymes bacterial cells induce the host cell to develop a lysosome‐like organelle called the parasitophorous vacuole (PV) where replication takes place. The PV starts small but grows in size to accommodate the increasing number of replicating cells. Manipulation of the host infection by C. burnetii includes altering Protein Kinase C (PKC) cell signaling events beginning at early times of the infection. PKC activation is initiated through multiple isoforms that sequentially phosphorylate downstream substrates. MARCKS is one of several PKC substrates phosphorylated during infections. The objective of this study was to localize MARCKS using antibodies and examine the role of MARCKS using specific inhibitors. Our results indicate that MARCKS localizes to the PV membrane and surrounding cytoplasm. The level of MARCKS protein was knocked‐down using siRNA treatment of HeLa cells. Infected cells treated with MARCKS siRNA contained C. burnetii, but many PV's were larger in size and contained fewer bacteria than those of infected cells treated with control siRNA. A peptide inhibitor of MARCKS appeared to have a similar effect on infected THP‐1 cells by causing enlarged PV's compared to control peptide treatments. These results indicate that MARCKS may have a role in regulating or controlling the size of C. burnetii‐induced PV's through manipulation of the host cell PKC signaling system.Support or Funding InformationSupported by a grant from Arkansas INBRE (NIH NIGMS P20 GM103429).
EriC2 Regulates Histamine Production Machinery via an Ion Transport‐Dependent Mechanism in Lactobacillus reuteri
Authors: Hall Anne , Engevik Melinda , Versalovic James 
Published: November 2023

BackgroundCertain strains of Lactobacillus reuteri can reduce inflammation and tissue damage in mouse models of colitis. This anti‐inflammatory capacity stems in part from L. reuteri’s ability to produce and secrete histamine, which can act on specific receptors present on mammalian cells. In the bacteria, histamine is generated by histidine decarboxylase (HdcA), and released from the cell by a histidine/histamine exchanger (HdcP). This process consumes protons, resulting in an increasingly alkaline intracellular pH and an inside‐negative membrane potential. These factors can suppress the activities of HdcA and HdcP. However, hdcA is not constitutively expressed, and it is unclear which signals may trigger its upregulation. Additionally, it is unknown how L. reuteri balances its internal ion environment during histamine production, especially in the presence of a complex external environment like the GI tract. A proton/chloride antiporter, EriC2, was recently identified in L. reuteri as a potential regulator of intracellular pH and membrane potential, and thus histamine production. We hypothesize that EriC2 maintains intracellular pH via proton influx and membrane potential via chloride efflux at levels that allow histamine production by L. reuteri.Methods & ResultsTo investigate how EriC2 ion transport might alter expression and function of histamine production machinery in L. reuteri, single‐strand recombineering was used to generate protein knockout, proton transport deficient, and transport null EriC2 strains. These mutations are stable, and do not significantly alter the growth of the resulting strains compared to wild‐type (WT) L. reuteri. Intracellular pH was assessed in each strain with the pH‐sensitive fluorophore, pHrodo Green AM. Loss of ion transport via EriC2 increases intracellular pH, supporting its potential role in maintaining the intracellular proton pool. RT‐qPCR showed that hdcA gene expression is increased in EriC2 transport mutants relative to the WT strain. T84 secretory colonic epithelial cells were co‐cultured with WT and EriC2 mutant L. reuteri strains. Host gene expression was examined via RT‐qPCR, and differential expression of histamine receptors was observed in the presence of mutant L. reuteri strains.ConclusionTogether these data suggest that EriC2 ion transport mutants differentially regulate histamine production machinery in L. reuteri, and can lead to changes in host physiology. The beneficial effects of L. reuteri‐derived histamine may depend on a regulatory system mediated by ion transport in the GI tract. A mechanistic understanding of histamine production by the gut microbiome may enable the development of diet or probiotic‐based strategies to suppress intestinal inflammation.
EXOCYTOSIS OF ENDOTHELIAL LYSOSOME‐RELATED ORGANELLES HAIR‐TRIGGERS A PATCHY LOSS OF GLYCOCALYX AT THE ONSET OF SEPSIS
Authors: Zullo Joseph A , Fan Jie , Azar Tala , Yen Wanyi , Zeng Min , Chen Jun , Ratliff Brian , Song Jun , Tarbell John M , Goligorsky Michael S , Fu Bingmei 
Published: November 2023

IntroductionEndothelial surface glycocalyx (ESG) is a well‐known regulator of leukocyte surveillance, vascular permeability, and a sensor of shear stress. ESG is degraded during sepsis, thus contributing to systemic multiorgan involvement. Our previous demonstration of a very early post‐stress exocytosis of lysosome‐related organelles (LRO) with their lytic enzymes led us to hypothesize that exocytosis of LRO may catapult a synchronized degradation of ESG.Methods and ResultsTo test this hypothesis we first analyzed the time‐course of exocytosis of Weibel‐Palade bodies and secretory lysosomes after application of lipopolysaccharides (LPS) to endothelial cells. Time‐lapse video microscopy revealed that LROs undergo agitation and vectorial movement with a time course of a few minutes after LPS. In addition, spectrophotometry measurements illustrated an increase of lysosomal cargo, cathepsin B, within the media after 10min of LPS exposure. Two therapeutic maneuvers, a nitric oxide intermediate, NG‐hydroxy‐L‐arginine (NOHA), and culture media conditioned by endothelial progenitor cells (EPC‐CM) reduced the directionality and motility of LRO. The patchy loss of ESG occurring with the similar fast kinetics was confirmed using confocal fluorescence microscopy and Stochastic Optical Reconstruction Microscopy. The loss of ESG was blunted by pretreatment with NOHA or EPC‐CM. Moreover, these treatments resulted in a significant reduction of mortality of septic mice.ConclusionIn summary, above studies provide the first demonstration of the very early patchy disintegration of ESG which can be prevented by pretreatment with NOHA and EPC‐CM, maneuvers that reduced exocytosis of LRO. Data support the hypothesis assigning to stress‐induced exocytosis of these organelles the role of a hair‐trigger for local degradation of ESG that in turn initiates leukocyte infiltration, increase in vascular permeability, and partially accounts for the later morbidity and mortality.Support or Funding InformationNIH grants DK54602, DK052783 and DK45462 (MSG), SC1CA153325 (BMF) and R01HL094889 (JMT and BMF); AHA grant 12SDG9080006 and ASN grant 010973‐101 (BBR); and The New York Community Trust ‐ Renal Clinical Fund (BBR)
Role of brainstem melanocortin‐4 receptor (MC4R) in regulating glucose, energy balance and body fat in female mice
Authors: Fang Taolin , do Carmo Jussara M , Wang Zhen , Aberdein Nicola , de Lara Rodriguez Cecilia Perez , Hall John E 
Published: November 2023

The central melanocortin system, particularly the melanocortin‐4 receptor (MC4R), plays an important role in regulation of energy homeostasis. Although the brainstem has a high density of MC4R, their role in regulating metabolic functions, including energy balance, glucose, and body weight has not been fully elucidated. Using Cre‐LoxP technology, we selectively rescued MC4R in preganglionic parasympathetic neurons of the nucleus tractus solitaries/dorsal motor nucleus of the vagus nerve (NTS/DMV) of female mice with whole body MC4R deficiency (Phox2b/LoxTB‐MC4R−/−, n=7). Littermate MC4R‐deficient mice (LoxTB‐MC4R−/−, n=7) were used as controls. Body weight, body composition, and glucose tolerance were determined at 20 weeks of age. At 19–22 weeks of age, the mice were placed in metabolic cages for measurement of daily food intake, oxygen consumption (VO2), heat production, and locomotor activity (MA). Compared to LoxTB‐MC4R−/− mice, Phox2b/LoxT‐MC4R−/− were less obese (38±3 vs. 47±1g) with decreased food intake (2.8±0.5 vs. 4.5±0.2 g), increased VO2 (65.5±2.9 vs. 60.0±0.4 mL·kg−1·min−1) and MA (306±49 vs. 99±6 cm·hr−1), and similar heat production (832±22 vs. 835±54 cal·hr−1). Phox2b/LoxTB‐MC4R−/− mice exhibited similar body fat percentage (45±1 vs. 46±2%) at 20 weeks of age compared to LoxTB‐MC4R−/−. Blood glucose levels and tolerance to a glucose load were similar (140±7 vs.138±13 mg·dL−1; AUC: 25866±2069 vs. 25097±4677 mg·min·dL−1) in Phox2b/LoxT‐MC4R−/− compared to LoxTB‐MC4R−/− mice. Rescuing MC4R in preganglionic parasympathetic neurons in the brainstem did not restore the anorexic (2.8±0.5 vs. 2.9±0.4 g) or the glucose lowering effects of leptin (125 ±32 to 121 ±30.5 mg·dL−1). These results suggest that MC4R activity in the brainstem, specifically in the NTS/DMV, contributes to regulation of appetite, body weight, energy expenditure, and locomotor activity in female mice. We did not observe a major role for MC4R in NTS/DMV in controlling fasting glucose, glucose tolerance, body fat percentage, or rescuing the anorexic and anti‐diabetic effects of leptin.Support or Funding Information(Supported by NHLBI‐PO1HL51971, NIGMS P20GM104357, and 15POST22960057).
Acute slow‐paced breathing modulates the pressor and depressor responses following spontaneous oscillations in muscle sympathetic nerve activity
Authors: Vianna Lauro C. , Fadel Paul J. , Joyner Michael J. , Wehrwein Erica A. 
Published: November 2023

Previous studies have indicated that acute slow‐paced breathing (6 breaths/min) significantly decreases arterial blood pressure (BP) in both normotensive and hypertensive individuals. More recent work suggested that muscle sympathetic nerve activity (MSNA) was unchanged during acute slow‐paced breathing, however, the pattern of MSNA firing was altered in that more periods of MSNA quiescence were present. Herein, we examined the ability of MSNA to modulate BP on a beat‐to‐beat basis. We hypothesized that the magnitude of the increase in BP following a burst of MSNA is attenuated during acute slow‐paced breathing contributing to the reduction in BP previously reported. BP (brachial catheter) and MSNA (peroneal microneurography) were continuously measured in 10 young (27 ± 1 years), healthy men during 10 minutes of normal spontaneous breathing (baseline) or paced breathing at six breaths per minute. Signal averaging was used to characterize changes in mean BP for 15 cardiac cycles following heartbeats associated with and without MSNA bursts. MSNA bursts were segregated as either single bursts (directly bordered by ≥1 heartbeat lacking MSNA) or multiple bursts (any burst positioned directly adjacent to another MSNA burst). Respiratory rate was 12 ± 1.1 breaths/min during baseline and 6 ± 0.7 breaths/min during slow‐paced breathing. Compared to baseline, mean BP was decreased during slow‐paced breathing (88±2 vs. 85±2 mmHg, P<0.05), whereas MSNA burst frequency was unchanged (13±2.2 vs. 13±2.4 bursts/min, P>0.05). At baseline, mean BP significantly increased following MSNA bursts (+3.2± 0.2 mmHg, P<0.05) and this increase was augmented during slow‐paced breathing (+5.0± 0.5 mmHg, P<0.05). There was a greater increase in mean BP following single as well as multiple MSNA bursts during slow‐paced breathing. In contrast, cardiac cycles without MSNA bursts (non‐bursts) were associated with a significant decrease in mean BP (−0.7± 0.1 mmHg, P<0.05), which was also augmented during slow‐paced breathing (−1.3± 0.3 mmHg, P<0.05). In summary, the pressor and depressor responses coupled to spontaneous oscillations in MSNA are augmented during slow paced breathing with a net effect of reduced BP. Thus, changes in MSNA firing pattern, without changes in burst frequency, can modulate resting BP.Support or Funding InformationFunding: NIH HL‐083947 (MJJ)
Impaired Arterial Pressure Stability Is Improved by Sodium‐glucose Co‐transporter 2 Inhibitor in Streptozotocin‐induced Diabetic Rat
Authors: Yoshikawa Tomoko , Kishi Takuya , Hirooka Yoshitaka 
Published: November 2023

BackgroundAlthough all anti‐diabetic agents could not certainly prevent cardiovascular events, arterial pressure (AP) reduction has been determined to have beneficial prevention for cardiovascular mortality in patients with diabetes mellitus (DM). Moreover, patients with DM have impaired AP variability. In these aspects, a new anti‐diabetic agent sodium‐glucose co‐transporter 2 (SGLT2) inhibitor has been focused on its unique AP lowering effect. We examined whether DM model rats would destabilize AP or not, and if so, whether SGLT2 inhibitor could ameliorate the disruptive AP lability.MethodsWe used streptozotocin‐induced diabetic (STZ) rats with telemetric AP monitoring. At 10 days after the injection of streptozotocin, SGLT2 inhibitor (ipragliflozin 1mg/kg/day) was orally administered to established hyperglycemic STZ rats for 15 days. We calculated the average and standard deviation (SD) of AP as the index of lability from AP histograms.ResultsAfter streptozotocin injection, mean AP did not change both in day (rest)‐time and night (active)‐time. SD of AP increased in rest‐time (3.2 mmHg to 3.7 mmHg, n=2) but not changed in active‐time. SGLT2 inhibitor for 15 days reduced mean AP both in rest‐ (−5.6 mmHg, n=2) and active‐time (−5.9 mmHg, n=2), and ameliorated SD of AP both in rest‐ (3.7 mmHg to 3.0 mmHg, n=2) and active‐time (3.5 mmHg to 2.5 mmHg, n=2).ConclusionsSGLT2 inhibitor ameliorates the disruptive AP lability in rest‐ and active‐time with depressor response in diabetic model rats.Support or Funding InformationThis study was supported by a Grant‐in‐Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (24390198 to Dr. Hirooka and 22790709 to Dr. Kishi).