bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vinorelbine Inhibits Pregnane X Receptor‐Mediated Induction of Cytochrome P450 3A4 Gene Expression in Human Hepatocytes
Authors: Chaudhury Chloe , Abbott Kodye , Pondugula Satyanarayana 
Published: November 2023

Pregnane X receptor (PXR), a ligand‐dependent nuclear receptor, is involved in regulating the gene expression of enzymes and proteins involved in endobiotic and xenobiotic metabolism. In particular, PXR plays a crucial role in regulating the gene expression of drug‐metabolizing enzymes, including cytochrome p450 3A4 (CYP3A4). In cancer patients, upregulation of the PXR target genes, including CYP3A4, can lead to not only adverse drug interactions but also chemoresistance. It is possible to inhibit the activity of PXR in order to overcome PXR‐mediated adverse drug interactions and chemoresistance. In this regard, a few PXR inhibitors or antagonists have been identified and characterized. However, these compounds fall short of reaching their clinical utility as they are non‐selective and/or highly‐toxic. Therefore, there is a practical need to develop a selective and less‐toxic PXR antagonist to overcome PXR‐mediated adverse drug interactions and chemoresistance. We sought to determine whether vinorelbine (VNB), a clinically‐used antimicrotubule agent, inhibits the transcriptional activity of PXR in human hepatocytes. PXR transactivation and cell viability assays were performed to determine CYP3A4 promoter activity and cytotoxicity, respectively, in HepG2 human liver carcinoma cells. Quantitative RT‐PCR assays were conducted to study gene expression of CYP3A4 in human primary hepatocytes. VNB, at its non‐cytotoxic and therapeutically‐relevant concentrations, inhibited PXR transactivation of CYP3A4 promoter activity. Additionally, VNB attenuated the PXR agonist‐induced gene expression of CYP3A4, suggesting that VNB downregulates CYP3A4 gene expression by inhibiting the activity of PXR. These results support our conclusion that VNB inhibits the transcriptional activity of PXR at its non‐cytotoxic and therapeutically relevant concentrations. Future studies will be directed to study the selectivity of VNB to PXR as well as the mechanisms of VNB inhibition of PXR‐mediated CYP3A4 induction.Support or Funding InformationThis work was supported by the Auburn University Research Initiative in Cancer Grant, Animal Health and Disease Research Grant, and Auburn University Startup Funds to Pondugula SR. The authors would like to thank Drs. Coleman, Tao, and Schwartz for sharing their research facilities.
Role of cGMP Signaling for Training‐induced Vascular and Skeletal Muscle Adaptations in Young and Older Humans
Authors: Piil Peter , Vorup Jacob , Gliemann Lasse , Egelund Jon , Hellsten Ylva , Nyberg Michael 
Published: November 2023

Aging is associated with impaired blood flow regulation; however, the mechanisms underlying this impairment and to what extent a period of exercise training can improve the matching between O2 delivery and utilization remain unclear. Eight young and 6 older (24 ± 1 vs. 74 ±2 years) healthy sedentary men participated in the study. We examined the vascular response to femoral arterial infusion of the vasoactive compound ATP and the effect of inhibiting the main enzyme involved in cGMP degradation, phosphodiesterase 5 (PDE5), on hemodynamics and O2 uptake in contracting skeletal muscle before and after 10 weeks of aerobic high intensity training. Catheters were placed in the femoral artery and vein of both legs. A microdialysis probe was inserted into one of the venous catheters to allow for measurements of plasma ATP concentrations. Measurements of blood flow, intra‐arterial and ‐venous blood pressure, and arterial and venous O2 content were performed during ATP infusion and knee‐extensor exercise. As post‐intervention testing is currently being conducted, only data from pre‐intervention testing is presented in is this abstract.At baseline, the ATP‐induced change in leg vascular conductance was lower in the older group (P<0.05). During sub maximal knee‐extensor exercise in the control setting, O2 uptake tended to be lower (−14%, P=0.093) in the older subjects compared to young subjects. After intake of the highly selective PDE5 inhibitor sildenafil, blood flow, leg vascular conductance and O2 uptake were higher (P<0.05) in the older group during knee‐extensor exercise whereas no changes were observed in the young group. These results indicate an insufficient oxygen delivery to the contracting skeletal muscle of aged individuals as a result of reduced cGMP signaling. Data from post‐intervention testing will provide insight as to whether exercise training can improve the matching of O2 delivery and utilization via improved cGMP signaling in the older subjects. Also, it is thought that ATP released from red blood cells and the endothelium play a role in blood flow regulation, and data from post‐intervention testing will elucidate if a period of exercise training increases ATP sensitivity and/or venous plasma ATP concentrations during exercise.Support or Funding InformationFinancial support for the study was provided by the Danish Council for Independent Research – Medical Sciences and Lundbeck Foundation.
Cardiac complement in Toll‐like receptor 4 KO mice subject to renal ischemia/reperfusion
Authors: da Cruz Junho Carolina Victoria , Sonoda Mayra Trentin , Ramos Marcela Sorelli Carneiro 
Published: November 2023

BackgroundThe immune system consists of an array of cells and molecules distributed throughout the organism; its function is to recognize antigens or molecular structures, generating an effective response in the pathogens destruction or inactivation. It can also act via the complement system (CS). The cardiac tissue is a main target of the immune system and several cardiovascular diseases (CVD) are preceded by general or local inflammation, contributing directly to cardiac remodeling and changes in heart tropism. It is known that renal ischemia/reperfusion (I/R) may result in the development of systemic inflammation and it can reach the cardiac tissue. Tissue response may be initiated by Toll‐like receptors [TLR‐ pathogen‐associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) recognizers] or also by complement system. Within the inflammatory process, the complement component C3a is released in abundance and binds to C3aR1 receptor, which might be involved in TLRs activation.AimSince it has been demonstrated that renal I/R is able to induce CH and ablation of TLR4 prevents such CH development, the aim of this study was to evaluate if TLR4 −/− had differential expression of complement components when compared to wild type mice.MethodsC57BL/6 male mice and C57BL/6 TLR 4 −/− were subjected to surgical occlusion of left renal pedicle for 60min followed for reperfusion (I/R) for 15 days. Morphometric analysis were performed using as parameters heart weight, kidneys weight and body weight. Real time PCR were utilized to analyze gene expression.ResultsThe C3aR component in KO group after 15 days of reperfusion, showed no change. These data is in accordance with previous data where we have not observed any modulation in the WT groups after 15 days of reperfusion. However, analysis of the complement component C3 mRNA levels, showed a significant increase in the WT I/R group compared to WT sham group (p <0.05), and TLR4 absence was capable of preventing such increase. The component C5R presents significant increase after 15 days of reperfusion (p <0.05) as well as Cfb (p<0.05) in TLR4 KO I/R animals, compared to Sham.ConclusionCardiac gene expression of complement components differs in WT and TLR4KO mice subjected to renal ischemia/reperfusion, indicating a possible interaction between these two main responses of innate immunity in our model.Support or Funding InformationFAPESP (São Paulo Research Foundation)
Acute and Chronic Biological Effects of Copeptin on Vascular Function in Mice and Humans
Authors: Rasor Madalyn , Wegman‐Points Lauren , Reho John J , Santillan Mark K , Grobe Justin L , Santillan Donna , Sindler Amy L , Rahmouni Kamal , Scroggins Sabrina , Pierce Gary L 
Published: November 2023

BackgroundCopeptin, the 39 amino acid C‐terminal segment of the precursor protein of arginine vasopressin (AVP), is secreted from the posterior pituitary in a 1:1 ratio with AVP in response to osmotic and hemodynamic stimuli. Copeptin is significantly elevated in pregnant women with preeclampsia, and predicts the development of preeclampsia as early as the 6th week of gestation. Preliminary data in a recent prospective study demonstrated that higher copeptin was associated with lower endothelial function (brachial artery flow‐mediated dilation, FMD) during the 2nd trimester in pregnant women at high risk of preeclampsia. However, whether copeptin itself has any independent biological effects on the vasculature is completely unknown.Methods and ResultsChronic incubation of mouse aortic rings with copeptin (n=4 male mice, 1nM, 24 hours) had no effect on endothelium‐ dependent (acetylcholine) or ‐independent (sodium nitroprusside) vasodilatory responses, indicating the lack of effect on endothelial or vascular smooth muscle function. Similarly, circulating copeptin was not associated with brachial artery FMD in non‐pregnant young women (n=11, r= −0.08, P=0.81), postmenopausal women (n=15, r=0.06, P=0.82) or men (n=24, r=0.10, P=0.62). In contrast, acute incubation of aortic rings (n=6 male mice) with copeptin demonstrated a dose response vasodilation beginning at 1nM up to a maximum relaxation at 100nM (43.6 ± 15.5%, p<0.05, n=6). Co‐incubation with the nitric oxide (NO) inhibitor of L‐NG‐Nitroarginine methyl ester (L‐NAME) significantly attenuated the max vasodilatory response to 12.5 ± 0.6%, indicating that the acute vascular response to copeptin is largely NO‐mediated. Incubation of aorta with copeptin (60 min, 0.5nM) caused a significant increase in protein kinase B (AktSer473) phosphorylation (Western blot) vs. control tissue (0.63 ± 0.19 vs 1.27 ± 0.6, p<0.04, n=5) and a trend towards increased phosphorylation of eNOSSer1177 (0.69 ± 0.02 vs 0.91 ± 0.21, p<0.3, n=2).ConclusionsThese data indicate that acute exposure of aorta of mice to high copeptin results in marked NO‐mediated vasodilation. However, chronic exposure to high copeptin does not alter vascular endothelial or smooth muscle function in mice nor is circulating copeptin associated with endothelial function in males or non‐pregnant females. This suggests that adverse vascular effects associated with chronically elevated copeptin concentrations in preeclampsia are more likely a result of the pathophysiological consequences of high AVP rather than copeptin.Support or Funding InformationAPS STRIDE Undergraduate Summer Research Fellowship;AHA 15SFRN23730000;University of Iowa Center for Research by Undergraduates (ICRU); University of Iowa Center for Hypertension Research.
High Glucose Concentration Attenuates Insulin‐Stimulated Protein Kinase B Levels In Cultured Astrocytes
Authors: Yu Eric , Cohen Susan , Liu Qiuli , Ryan Robert , Gebremedhin Debebe , Harder David , Rarick Kevin 
Published: November 2023

BACKGROUNDGlucoregulatory abnormalities have been implicated to contribute to the pathophysiology of Alzheimer‐type dementia. The brain requires insulin for supply of energy critical for processing of memory and cognition. Insulin acts on the insulin receptor initiating signaling cascades that activate protein kinase B (Akt) through phosphorylation (p‐Akt) in cultured astrocytes. However, it is not yet clear whether the insulin induced production of p‐Akt could be attenuated by high glucose concentrations through stimulation of an inhibitory signaling pathway involving activation of protein kinase C (PKC).OBJECTIVEThe objective of our study is to examine the phosphorylation of Akt in cultured neonatal astrocytes following insulin stimulation and to determine if this response could be attenuated by culturing astrocytes in high glucose media via activation of PKC.METHODSNeonatal astrocyte cultures were derived from rat hippocampus and cultured for three passages in normal (5.5 mM) or high glucose (25 mM) media. Astrocyte cultures were stimulated with increasing concentrations of insulin (10−11 to 10−6 M) and Western immunoblotting analysis was used to determine protein levels of p‐Akt and insulin receptor. Protein levels of PKC isoforms (alpha, gamma, and delta) were determined in whole cell lysates from separate astrocyte cultures grown in normal or high glucose media.RESULTSInsulin‐induced a dose‐dependent increase in p‐Akt protein level in astrocytes cultured in normal glucose. However, insulin stimulation of astrocytes cultured in high glucose media resulted in an attenuated protein level of p‐Akt (100 nM insulin: 3.6 ± 1.0 vs. 8.9 ± 1.6 fold increase compared to control), requiring more insulin to increase the protein levels of p‐Akt (interaction effect: p = 0.024). The protein levels of insulin receptor in cultured astrocytes also increased in response to stimulation with insulin. Astrocytes cultured in high glucose media exhibited increased protein levels of PKC alpha (1.5 fold increase, p < 0.05) and gamma (2 fold increase, p < 0.05) but not of the PKC delta isoform compared to astrocytes cultured in normal glucose media.CONCLUSIONSInsulin‐dependent intracellular signaling involving phosphorylation of Akt is attenuated in astrocytes cultured in high glucose media. Astrocytes respond to increased environmental glucose with isoform specific increases in PKC protein levels which may have resulted in negative regulation of astrocyte insulin receptor signaling.Support or Funding InformationFunding from NIH (NHLBI) T35 HL072483, R01 HL033833 and HL105997 and the Veterans Administration Research Career Scientist Award.
Beneficial effects of physical exercise under lightening condition on progressive cartilage damage
Authors: Hong Yunkyung , Jo Youngjin , Kim Hyunsoo , Hong Yonggeun 
Published: November 2023

Osteoarthritis (OA) is frequently occurred in the elderly people. Physical exercise used to be recommended for OA patients, but the effects differ as to how to take exercise. Collagenase‐induced early OA rats were subjected to determine whether environmental light diminishes the beneficial effects of physical exercise on the degenerative musculoskeletal unit. Motor‐driven treadmill exercise (Ex) was applied for 30 min (22:00) on 5 days/week. Intervention was performed for 4 weeks under constant light (LL) as well as 12:12hr light‐dark (L/D). The elevated Mmp13 expression was reduced in the L/D+Ex group, but it was reversed when exercise was executed under LL condition. Exercise under L/D prevented loss of type II collagen (COL2A1) in the cartilage specimens, the effect of which was mitigated in LL condition. Concomitant with these results, the value of joint thickness was recovered in the L/D+Ex group only. Exercise activated autophagic machinery in the periarticular muscle regardless of light condition, the extent of which was higher in the L/D+Ex group than the LL+Ex group. However, CHOP protein was more present in the LL+Ex group. Taken together, musculoskeletal remodeling induced by physical exercise might be affected by lightening condition in vivo animal model.Support or Funding InformationNRF‐2012R1A1A2005089, NRF‐2013R1A2A2A01067169, NRF‐2015R1C1A2A01055691
Liver specific depletion of mitochondrial ATP transporter enhances uncoupled respiration and prevents fatty liver and obesity
Authors: Cho Joonseok , Zhang Yujian , Sunny Nishanth E , Kim Jae‐Sung , Shiratsuchi Takayuki , Oh S. Paul , Lee Young Jae , Terada Naohiro 
Published: November 2023

Adenine nucleotide translocases (ANTs), also called ADP/ATP carriers (AACs), transport ADP and ATP through the mitochondrial inner membrane and play an essential role for mitochondrial energy supply in eukaryotes. In the liver mitochondria, Ant2 is predominantly expressed among the three murine Ant paralogs Ant1, 2 and 4. When we conditionally disrupted the Ant2 gene in the liver using Alb‐Cre mice, ADP/ATP exchange capacity in the liver mitochondria was indeed inhibited over 96%.Surprisingly, the mice appeared normal though they had a noticeably leaner phenotype compared to WT mice. These null mice did not show signs of liver dysfunction for over 10 months suggesting mitochondrial ATP supply is largely dispensable for basal liver function and homeostasis. Upon closer examination of Ant2 depleted liver mitochondria, both outer and inner membranes were intact, and the membrane potential was maintained normally. Notably, mitochondrial mass was significantly increased in Ant2‐depleted hepatocytes, where basal respiration was upregulated due to an increase in uncoupled respiration. In addition, liver specific Ant2 knockout mice demonstrated low blood glucose, cholesterol, and insulin levels and improved glucose tolerance. These data indicate that the Ant2 depleted mitochondria in the liver become highly uncoupled and consequently energy‐inefficient, but remain intact yielding no apparent adverse effects to the organ or systemically to the body. Indeed, when mice subjected to high fat/fructose diet, the liver specific Ant2 knockout mice developed significantly less fatty liver changes and less obesity than controls. In addition, when wild type mice were subjected to a low dose of the general Ant inhibitor, carboxyatractyloside, during high fat/fructose diet regimens, the drug also partially mitigated fatty liver changes and obesity. Of interest, liver Ant2 expression in wild type mice is significantly decreased by high fat/fructose diet but increased by fasting. Further, In vitro treatment of a hepatic cell line with a high concentration of fatty acids demonstrated reduced human ANT2 expression. These indicate that there is a physiological mechanism to control Ant2 expression under high‐fat diet conditions which may help prevent obesity and fatty liver.Given the beneficial effects that we identified here with liver‐specific Ant depletion and systemic Ant inhibition combined with high fat diet, targeted manipulation of hepatic mitochondrial metabolism, particularly through inhibition of Ant2, could represent a novel strategy to prevent fatty liver and obesity.Support or Funding Informationresearch grant from Otsuka Maryland Medicinal Laboratories
Plasma Soluble Erythropoietin Receptor is Decreased During Sleep in Andean Highlanders with Chronic Mountain Sickness
Authors: Corante Noemi , Anza‐Ramirez Cecilia , Figueroa‐Mujica Romulo , Vizcardo‐Galindo Gustavo , Mercado Andy , Macarlupú Jose Luis , León‐Velarde Fabiola , Villafuerte Francisco 
Published: November 2023

Excessive erythrocytosis (EE) is the main sign of Chronic Mountain Sickness (CMS), a maladaptive syndrome with significant prevalence in high‐altitude inhabitants. Although chronic hypoxemia represents its underlying stimulus, the fundamental pathophysiological mechanism is still debatable. Studies during sleep in CMS patients consistently find lower average pulse O2 saturation (SpO2) compared to healthy highlanders (HH). Although, whether accentuated hypoxemia during sleep has a significant impact on the Epo system that could explain the occurrence of EE is still unclear. We have recently shown that morning soluble Epo receptor (sEpoR), an endogenous Epo antagonist, is decreased in CMS patients suggesting increased circulating Epo availability (increased Epo/sEpoR). The aim of the present study was to characterize the concentration profile of sEpoR and serum Epo during night‐time, and their relationship with SpO2 and hematocrit (Hct) in HH and CMS patients, as well as the association between testosterone concentration and Epo and sEpoR at early morning. Thirty‐nine male participants (CMS, n=23; HH, n=16) from Cerro de Pasco, Perú at 4340m, between 21 and 65 years old and with normal iron status participated in the study. Blood samples were taken every 4h from 6pm–6am for Epo and sEpoR measurements; the morning sample was also used for evaluation of serum iron, ferritin, transferrin and testosterone concentrations. SpO2 was assessed at 6pm and continuously monitored from 10pm–6am. Mean SpO2 during sleep was lower in CMS patients compared to HH (75.2±1.5 vs 79.9±0.9%), and the percentage of sleep‐time spent with SpO2 below 80% was higher (67.2±7.2 vs 37.9±8.5%). The CMS group showed higher Epo from 6pm–2am (24.1±2.6 vs 14.0±2.2, 26.4±4.4 vs 10.5±0.9 and 25.3±3.8 vs 11.3±1.3mIU/mL, respectively) and lower sEpoR from 10pm–6am (1.4±0.1 vs 2.2±0.1, 1.5±0.2 vs 2.2±0.2 and 1.5±0.1 vs 2.2±0.2 ng/mL, respectively). Consequently, the Epo/sEpoR was significantly higher in the CMS group from 6pm–6am (15.8±2.5 vs 7.7±1.0, 20.9±3.7 vs 5.2±0.7, 20.5±3.8 vs 5.7±0.8 and 20.7±3.9 vs 6.8±0.8 mIU/ng, respectively). Multiple regression analysis showed mean sleep‐time SpO2 and Epo/sEpoR as significant predictors of Hct corrected for potential confounders (age, body mass index and serum testosterone). Total and free testosterone levels were not associated to Hct, nor to the erythropoietic factors. In conclusion, our results show a sustained erythropoietic stimulus driven by the Epo system in CMS patients, further enhanced by the continuous exposure to accentuated hypoxemia during sleep.Support or Funding InformationSupported by The Wellcome Trust grant 097275/Z/11/Z
Tumor Necrosis Factor‐α Receptor 1 (TNFR1) Knockdown in Subfornical Organ (SFO) Attenuates Central Expression of Excitatory Mediators and Ameliorates Peripheral Manifestations of Heart Failure in Rats after Myocardial Infarction
Authors: YU YANG , Wei Shun‐Guang , Weiss Robert M , Felder Robert B 
Published: November 2023

Myocardial infarction (MI)‐induced heart failure (HF) is a systemic inflammatory state characterized by increased circulating proinflammatory cytokines (PICs). Circulating PICs up‐regulate inflammation and renin‐angiotensin system (RAS) activity in cardiovascular regions of the brain, contributing to sympathetic excitation and the progression of HF. We recently demonstrated that the subfornical organ (SFO), a forebrain circumventricular organ that lacks a blood–brain barrier, is a predominant site in the brain at which circulating PICs act to elicit cardiovascular and sympathetic responses. Here we tested the hypothesis that tumor necrosis factor‐α receptor1 (TNFR1) knockdown in the SFO would modulate the MI‐induced expression of excitatory mediators in the SFO and downstream in the hypothalamic paraventricular nucleus (PVN) that mediate hemodynamic and sympathetic responses, and would ameliorate the peripheral manifestations of HF after MI. Rats received SFO microinjections of a TNFR1 shRNA or scrambled shRNA lentiviral vector carrying green fluorescent protein (GFP), or vehicle. One week later, transfection potential of the lentiviral vector was examined in some rats receiving SFO TNFR1 shRNA; other rats underwent coronary ligation to induce HF confirmed by echocardiography, or a sham operation. One week after SFO microinjections of TNFR1 shRNA, GFP fluorescence was visualized in the SFO but not in other brain areas. Four weeks after MI, HF+vehicle rats had increased mRNA of TNFR1, NF‐κB p65, cyclooxygenase (COX)‐2, angiotensin II type 1 receptor (AT1R) and c‐fos, and decreased mRNA of IkB‐α in both SFO and PVN, compared with SHAM+vehicle rats. HF+TNFR1 shRNA rats, but not HF+scrambled shRNA rats, had reduced mRNA of TNFR1 in the SFO, associated with decreased mRNA of NF‐κB p65, COX‐2, AT1R and c‐fos and elevated mRNA of IkB‐α not only in SFO but also in PVN. HF+vehicle rats also had increased plasma norepinephrine levels, lung/body weight and right ventricle/body weight ratios, which were attenuated in HF+ TNFR1 shRNA but not in HF+scrambled shRNA rats. The results suggest that HF‐induced increases in circulating TNF‐α act upon TNFR1 in the SFO to upregulate excitatory mediators in the SFO and downstream in the PVN, contributing to sympathetic excitation and cardiac dysfunction in HF. TNFR1 in the SFO may be a novel target for therapeutic intervention in inflammatory cardiovascular conditions like heart failure and hypertension.Support or Funding InformationSupported by NIH Grants HL‐073986 and HL‐096671 and Department of Veterans Affairs.