Phosphorylation of eNOS initiates excessive NO production in early phases of portal hypertension

2002 ◽  
Vol 282 (6) ◽  
pp. H2084-H2090 ◽  
Author(s):  
Yasuko Iwakiri ◽  
Ming-Hung Tsai ◽  
Timothy J. McCabe ◽  
Jean-Philippe Gratton ◽  
David Fulton ◽  
...  
Keyword(s):  
Portal Hypertension ◽  
Specific Activity ◽  
Ex Vivo ◽  
Active Form ◽  
Initial Increase ◽  
No Production ◽  
Portal Vein Ligation ◽  
Sprague Dawley ◽  
Perfusion Studies

Akt, also known as protein kinase B, is a serine/threonine kinase. Akt becomes active when phosphorylated by the activation of receptor tyrosine kinases, G protein-coupled receptors, and mechanical forces such as shear stress. Studies in vitro have shown that Akt can directly phosphorylate endothelial nitric oxide (NO) synthase (eNOS) and activate the enzyme, leading to NO production. The aim of this study was to test the hypothesis that the phosphorylation of eNOS plays a role in the enhanced NO production observed in early portal hypertension. Male Sprague-Dawley rats were subjected to either sham or portal vein ligation (PVL), and mesenteric arterial beds were used for ex vivo perfusion studies. Mesenteric arterial beds from PVL rats had an approximately 60–70% decrease in response to methoxamine (an α1-agonist and vasoconstrictor) compared with the sham group ( P < 0.01). When N G-monomethyl-l-arginine (a NOS inhibitor) was added to the perfusion, the difference in perfusion pressure between the two groups was abolished, suggesting that enhanced NO production in the PVL group blunted the response to the vasoconstrictor. The reduced responsiveness in PVL was not due to changes in eNOS expression but was due to an increase in enzyme-specific activity, suggesting posttranslational modification of eNOS. The phosphorylation of eNOS at Ser1176 was significantly increased by twofold ( P < 0.05) in the PVL group. Furthermore, PVL significantly increased Akt phosphorylation (an active form of Akt) by threefold ( P< 0.05). When vessels were treated with wortmannin (10 nM) to block the phosphatidylinositol-3-OH-kinase/Akt pathway, NO-induced vasodilatation was significantly reduced. These results suggest that the phosphorylation of eNOS by Akt activates the enzyme and may be the first step leading to an initial increase in NO production in portal hypertension.

Decreased vascular contractile and inositol phosphate responses in portal hypertensive rats

1995 ◽  
Vol 73 (3) ◽  
pp. 378-382 ◽  
Author(s):  
Yi-Tsau Huang ◽  
Chuang-Ye Hong ◽  
Pi-Chin Yu ◽  
Ming-Fang Lee ◽  
May C. M. Yang ◽  
...  
Keyword(s):  
Portal Hypertension ◽  
Contractile Response ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Venous Pressure ◽  
Portal Vein Ligation ◽  
Sprague Dawley ◽  
Hypertensive Rats ◽  
Contractile Responses ◽  
Tail Artery

The purpose of this study was to investigate the vascular contractile and inositol phosphate responses in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague–Dawley rats. Sham-operated rats served as controls. Pressures, vasoconstrictor responses, and inositol phosphate responses were determined at 14 days after surgery. The portal venous pressure was significantly higher, while systemic arterial pressure and heart rate were lower, in PVL rats. Dose-dependent contractile responses were observed for both norepinephrine (1 × 10−8 – 3 × 10−6 M) and vasopressin (3 × 10−10 – 3 × 10−8 M) in the tail artery of both groups. The contractile response to norepinephrine was significantly decreased in PVL rats compared with controls at all doses. The contractile response to vasopressin was significantly decreased in PVL rats at higher doses. After myo-[3H]inositol incorporation in tail artery, the levels of 3H-labelled phosphatidylinositols (cpm/mg) were similar between the two groups. Norepinephrine (10−7 – 10−5 M) and vasopressin (10−10 – 10−8 M) dose dependently stimulated the 3H-labelled inositol phosphate production in the tail artery of both PVL and sham-operated rats. However, the response was significantly lower in PVL rats. The results suggested that the attenuation of vascular contractile responses in portal hypertension was reflected in the phosphoinositide messenger system.Key words: portal hypertension, inositol phosphates, phosphoinositide, tail artery, contractile response.

scholarly journals Calcitriol Promotes Differentiation of Glioma Stem-Like Cells and Increases Their Susceptibility to Temozolomide

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3577
Author(s):  
Julia Gerstmeier ◽  
Anna-Lena Possmayer ◽  
Süleyman Bozkurt ◽  
Marina E. Hoffmann ◽  
Ivan Dikic ◽  
...  
Keyword(s):  
Vitamin D3 ◽  
Ex Vivo ◽  
Active Form ◽  
Treatment Resistance ◽  
Serum Levels ◽  
Disease Recurrence ◽  
Primary Brain Tumor ◽  
High Rate ◽  
Therapeutic Doses

Glioblastoma (GBM) is the most common and most aggressive primary brain tumor, with a very high rate of recurrence and a median survival of 15 months after diagnosis. Abundant evidence suggests that a certain sub-population of cancer cells harbors a stem-like phenotype and is likely responsible for disease recurrence, treatment resistance and potentially even for the infiltrative growth of GBM. GBM incidence has been negatively correlated with the serum levels of 25-hydroxy-vitamin D3, while the low pH within tumors has been shown to promote the expression of the vitamin D3-degrading enzyme 24-hydroxylase, encoded by the CYP24A1 gene. Therefore, we hypothesized that calcitriol can specifically target stem-like glioblastoma cells and induce their differentiation. Here, we show, using in vitro limiting dilution assays, quantitative real-time PCR, quantitative proteomics and ex vivo adult organotypic brain slice transplantation cultures, that therapeutic doses of calcitriol, the hormonally active form of vitamin D3, reduce stemness to varying extents in a panel of investigated GSC lines, and that it effectively hinders tumor growth of responding GSCs ex vivo. We further show that calcitriol synergizes with Temozolomide ex vivo to completely eliminate some GSC tumors. These findings indicate that calcitriol carries potential as an adjuvant therapy for a subgroup of GBM patients and should be analyzed in more detail in follow-up studies.

scholarly journals Expression of Active Human Tissue-Type Plasminogen Activator in Escherichia coli

1998 ◽  
Vol 64 (12) ◽  
pp. 4891-4896 ◽  
Author(s):  
Ji Qiu ◽  
James R. Swartz ◽  
George Georgiou
Keyword(s):  
Escherichia Coli ◽  
Plasminogen Activator ◽  
Disulfide Bonds ◽  
Specific Activity ◽  
Active Form ◽  
Tissue Type ◽  
Heterologous Proteins ◽  
E Coli ◽  
Disulfide Isomerases

ABSTRACT The formation of native disulfide bonds in complex eukaryotic proteins expressed in Escherichia coli is extremely inefficient. Tissue plasminogen activator (tPA) is a very important thrombolytic agent with 17 disulfides, and despite numerous attempts, its expression in an active form in bacteria has not been reported. To achieve the production of active tPA in E. coli, we have investigated the effect of cooverexpressing native (DsbA and DsbC) or heterologous (rat and yeast protein disulfide isomerases) cysteine oxidoreductases in the bacterial periplasm. Coexpression of DsbC, an enzyme which catalyzes disulfide bond isomerization in the periplasm, was found to dramatically increase the formation of active tPA both in shake flasks and in fermentors. The active protein was purified with an overall yield of 25% by using three affinity steps with, in sequence, lysine-Sepharose, immobilized Erythrina caffra inhibitor, and Zn-Sepharose resins. After purification, approximately 180 μg of tPA with a specific activity nearly identical to that of the authentic protein can be obtained per liter of culture in a high-cell-density fermentation. Thus, heterologous proteins as complex as tPA may be produced in an active form in bacteria in amounts suitable for structure-function studies. In addition, these results suggest the feasibility of commercial production of extremely complex proteins inE. coli without the need for in vitro refolding.

Cultured adult cardiac myocytes maintain protein synthetic capacity of intact adult hearts

1993 ◽  
Vol 264 (2) ◽  
pp. H573-H582
Author(s):  
W. A. Clark ◽  
S. J. Rudnick ◽  
D. G. Simpson ◽  
J. J. LaPres ◽  
R. S. Decker
Keyword(s):  
Protein Synthesis ◽  
Cardiac Myocytes ◽  
Synthesis Rate ◽  
Initial Increase ◽  
Heart Cells ◽  
Adult Cardiomyocytes ◽  
Perfusion Studies ◽  
Adult Cardiac Myocytes ◽  
Synthetic Capacity

Previous studies have shown that the rates of protein synthesis observed in embryonic and neonatal heart cells in culture are as much as nine times greater than the rates of synthesis observed in the intact adult heart either in situ or in isolated perfusion studies. This study addressed whether adult cardiomyocytes in long-term culture maintain the protein synthetic capacity of the adult myocardium or, rather, whether the protein synthetic capacity expands or falls as adult cardiac myocytes progress in culture. Protein synthesis was evaluated in isolated adult feline cardiomyocytes maintained in serum and insulin-supplemented medium for up to 53 days in vitro. With the use of both pulse- and saturation-labeling techniques it was determined that the rate of protein synthesis in adult cardiomyocytes was maintained at a level very close to that observed in the intact heart for over 1 mo in culture. Saturation-labeling studies indicate a fractional rate of protein synthesis at 6.1%/day and an absolute synthesis rate of 1,300 nmol leucine incorporated.g protein-1.h-1. Pulse-labeling studies revealed an initial increase in protein synthesis rates during adaptation to culture and a further increase after activation of beating and cellular hypertrophy.

scholarly journals Vitamin D alleviates oxidative stress in adipose tissue and mesenteric vessels from obese patients with subclinical inflammation

2020 ◽  
Vol 98 (2) ◽  
pp. 85-92 ◽  
Author(s):  
Mihaela Ionica ◽  
Oana M. Aburel ◽  
Adrian Vaduva ◽  
Alexandra Petrus ◽  
Sonia Rațiu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Vitamin D ◽  
Adipose Tissue ◽  
Vascular Function ◽  
Ex Vivo ◽  
Active Form ◽  
Reactive Oxygen Species Generation ◽  
Obese Patients ◽  
Tissue Samples

Obesity is an age-independent, lifestyle-triggered, pandemic disease associated with both endothelial and visceral adipose tissue (VAT) dysfunction leading to cardiometabolic complications mediated via increased oxidative stress and persistent chronic inflammation. The purpose of the present study was to assess the oxidative stress in VAT and vascular samples and the effect of in vitro administration of vitamin D. VAT and mesenteric artery branches were harvested during abdominal surgery performed on patients referred for general surgery (n = 30) that were randomized into two subgroups: nonobese and obese. Serum levels of C-reactive protein (CRP) and vitamin D were measured. Tissue samples were treated or not with the active form of vitamin D: 1,25(OH)2D3 (100 nmol/L, 12 h). The main findings are that in obese patients, (i) a low vitamin D status was associated with increased inflammatory markers and reactive oxygen species generation in VAT and vascular samples and (ii) in vitro incubation with vitamin D alleviated oxidative stress in VAT and vascular preparations and also improved the vascular function. We report here that the serum level of vitamin D is inversely correlated with the magnitude of oxidative stress in the adipose tissue. Ex vivo treatment with active vitamin D mitigated obesity-related oxidative stress.

Pharmacokinetics, Pharmacodynamics and Tolerability of a Potent, Non-peptidic, GP IIb/IIIa Receptor Antagonist following Multiple Oral Administrations of a Prodrug Form

1998 ◽  
Vol 79 (01) ◽  
pp. 169-176 ◽  
Author(s):  
Nishit Modi ◽  
Sherron Bullens ◽  
Cheryl Pater ◽  
Michael Lipari ◽  
Kirk Robarge ◽  
...  
Keyword(s):  
Half Life ◽  
Rhesus Monkeys ◽  
Ex Vivo ◽  
Active Form ◽  
Plasma Concentrations ◽  
Volume Of Distribution ◽  
A Value ◽  
Terminal Half Life ◽  
The Right

SummaryRo 44-3888 is a potent and selective antagonist of GP IIb/IIIa. Following IV administration to rhesus monkeys, the (mean ± SD.) clear ance, volume of distribution and terminal half-life of Ro 44-3888 were 4.4 ± 1.8 ml/min/kg, 0.8 ± 0.4 l/kg and 2.5 ± 0.8 h respectively. Oral administration of Ro 48-3657 (1 mg/kg), a doubly protected prodrug form, produced peak concentrations of Ro 44-3888 (152 ± 51 ng/ml), 4.2 ± 2.2 h after dosing. Terminal half-life and estimated bioavailabil ity were 5.1 ± 1.6 h and 33 ± 6% respectively. No effect on blood pressure, heart rate or platelet counts were seen. Adenosine diphosohate (ADP) induced platelet aggregation (PA) and cutaneous bleeding times (CBT) were determined prior to and after the last of 8 daily oral administrations of Ro 48-3657 (0.25 or 0.5 mg/kg) to eight rhesus monkeys. Peak and trough plasma concentrations were proportional to dose and steady state was achieved after the second administration. Inhibition of PA and prolongation of CBT were concentration dependent. The ex vivo IC50 (82 nM) for ADP-mediated PA correlated with a value (58 nM) determined in vitro. The CBT response curve was displaced to the right of the PA curve. CBT was prolonged to ≥25 min when levels of Ro 44-3888 exceeded 190 nM and PA was >90% inhibited. Therefore, in rhesus monkeys, Ro 48-3657 is reproducibly absorbed and converted to its active form, is well tolerated, and has a concentration-dependent effect on PA and CBT. These properties make Ro 48-3657 an attractive candidate for evaluation in patients at high risk for arterial thrombosis.

scholarly journals Complex formation between urokinase and plasma protein C inhibitor in vitro and in vivo

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 722-728 ◽  
Author(s):  
M Geiger ◽  
K Huber ◽  
J Wojta ◽  
L Stingl ◽  
F Espana ◽  
...  
Keyword(s):  
Complex Formation ◽  
Protein C ◽  
Specific Activity ◽  
Ex Vivo ◽  
Plasminogen Activator Inhibitor ◽  
Enzyme Linked Immunosorbent Assay ◽  
Plasma Samples ◽  
Protein C Inhibitor

Abstract Protein C inhibitor (PCI) and plasminogen activator inhibitor 3 (PAI-3; urinary urokinase inhibitor) are immunologically identical. The role of PCI for urokinase (uPA) inhibition in vivo was investigated. We therefore developed an enzyme-linked immunosorbent assay (ELISA) specific for uPA-PCI complexes: Rabbit anti-PCI IgG was immobilized on a microtiter plate and following incubation with uPA-PCI complex- containing samples, bound uPA-PCI complexes were quantified with a horseradish-peroxidase-linked monoclonal antibody (MoAb) to uPA. Using this assay, time, dose, and heparin-dependent complexes were detected when uPA was incubated with normal plasma or purified urinary PCI, whereas no complexes were measurable using PCI-immunodepleted plasma. Plasma samples (containing 20 mmol/L benzamidine to prevent complex formation ex vivo) from patients undergoing systemic urokinase therapy (1 x 10(6) IU/60 min intravenously [IV]) after myocardial infarction were also studied. uPA present in these plasma samples (up to 1,200 ng/mL) had only 43% to 70% of the specific activity of purified 2-chain uPA, suggesting that a major portion of uPA is complexed to inhibitors. In these plasma samples uPA-PCI complexes were present in a concentration corresponding to 21% to 25% of inactive uPA antigen. These data suggest that at high uPA concentrations, such as during uPA therapy, plasma PCI might contribute significantly to uPA inhibition in vivo.

In vitro hyporeactivity to methoxamine in portal hypertensive rats: reversal by nitric oxide blockade

1992 ◽  
Vol 262 (6) ◽  
pp. G996-G1001 ◽  
Author(s):  
C. C. Sieber ◽  
R. J. Groszmann
Keyword(s):  
Nitric Oxide ◽  
Portal Hypertension ◽  
Muscle Tone ◽  
Portal Vein Ligation ◽  
Alpha Adrenoceptor ◽  
No Formation ◽  
Adrenoceptor Agonist ◽  
Mesenteric Arterial Bed ◽  
Vascular Smooth Muscle Tone

The endothelial cell plays an important role in the local control of vascular smooth muscle tone. Portal hypertension is accompanied by systemic vasodilatation and a decreased response to vasoconstrictors, changes especially evident in the superior mesenteric arterial bed. To evaluate a possible effect of the locally released endothelium-derived relaxing factor nitric oxide (NO), we tested the effect of NO blockade in in vitro perfused superior mesenteric arterial beds of normal (sham) and portal hypertensive (PVL) rats, induced by partial portal vein ligation. A significant (n = 7/group; P = 0.02) hyporeactivity to the vasoconstrictive properties of the alpha-adrenoceptor agonist methoxamine (3 x 10(-6) to 3 x 10(-4) M) was prevented by blocking NO formation in PVL compared with sham rats, using the stereospecific biosynthesis antagonist N omega-nitro-L-arginine (10(-4) M, n = 7/group; NS for all methoxamine concentrations tested). This effect was reversed by the NO precursor L-arginine (10(-3) M, n = 5/group). In conclusion, these in vitro results in mesenteric vessels demonstrate that 1) portal hypertension is accompanied by a hyporeactivity to the vasopressor methoxamine and 2) locally released NO in this preparation is responsible for the decreased vasoconstrictive response.

scholarly journals Studies to Elucidate the Mechanism of Cardio Protective and Hypotensive Activities of Anogeissus acuminata (Roxb. ex DC.) in Rodents

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3471
Author(s):  
Fatima Saqib ◽  
Muhammad Arif Aslam ◽  
Khizra Mujahid ◽  
Luigi Marceanu ◽  
Marius Moga ◽  
...  
Keyword(s):  
Creatine Kinase ◽  
Ex Vivo ◽  
Inflammatory Cells ◽  
Left Ventricular ◽  
Guanosine Monophosphate ◽  
Sprague Dawley ◽  
Positive Effects ◽  
Creatine Kinase Mb

Anogeissus acuminata (Roxb. ex DC.) is a folkloric medicinal plant in Asia; including Pakistan; used as a traditional remedy for cardiovascular disorders. This study was planned to establish a pharmacological basis for the trivial uses of Anogeissus acuminata in certain medical conditions related to cardiovascular systems and to explore the underlying mechanisms. Mechanistic studies suggested that crude extract of Anogeissus acuminata (Aa.Cr) produced in vitro cardio-relaxant and vasorelaxant effects in isolated paired atria and aorta coupled with in vivo decrease in blood pressure by invasive method; using pressure and force transducers connected to Power Lab Data Acquisition System. Moreover; Aa.Cr showed positive effects in left ventricular hypertrophy in Sprague Dawley rats observed hemodynamically by a decrease in cardiac cell size and fibrosis; along with absence of inflammatory cells; coupled with reduced levels of angiotensin converting enzyme (ACE) and renin concentration along with increased concentrations of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP). In Acute Myocardial Infarction (AMI) model; creatine kinase (CK), creatine kinase-MB (CK-MB) and lactic acid dehydrogenase (LDH levels) were found to be decreased; along with decreased necrosis; edema and recruitment of inflammatory cells histologically. In vivo and ex vivo studies of Anogeissus acuminata provided evidence of vasorelaxant; hypotensive and cardioprotective properties facilitated through blockage of voltage-gated Ca++ ion channel; validating its use in cardiovascular diseases

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