Trans-stimulation of 13NH4+ efflux provides evidence for the cytosolic origin of tracer in the compartmental analysis of barley roots

2003 ◽  
Vol 30 (12) ◽  
pp. 1233 ◽  
Author(s):  
Dev T. Britto ◽  
Herbert J. Kronzucker
Keyword(s):  
Compartmental Analysis ◽  
Fold Increase ◽  
Model System ◽  
Hordeum Vulgare L ◽  
Root Cells ◽  
Transport Studies ◽  
Efflux Kinetics ◽  
Insight Into ◽  
Pool Sizes ◽  
Stimulation Of

The analysis of tracer efflux kinetics is fundamental to membrane transport studies, but requires the rigorous identification of subcellular tracer sources. We present a solution to this problem through the analysis of sharp increases in 13NH4+ efflux from roots of radiolabelled barley (Hordeum vulgare L.) seedlings, in response to a 100-fold increase in external [NH4+]. By comparing these trans-stimulation data with a mathematical model incorporating changes in subcellular NH4+ fluxes and pool sizes, we show that the cytosol of root cells is the origin of the tracer efflux. Our analysis provides new insight into the rapidly occurring events underlying compensatory flux regulation during transitions from one nutritional steady state to another, and confirms the validity of compartmental analysis by tracer efflux (CATE) in this important model system.

TSH SYNTHESIS AND RELEASE IN THE THYROIDECTOMIZED RAT:

1979 ◽  
Vol 92 (3) ◽  
pp. 489-501 ◽  
Author(s):  
O. Spira ◽  
A. Birkenfeld ◽  
J. Gross ◽  
A. Gordon
Keyword(s):  
Steady State ◽  
Compartmental Analysis ◽  
Fold Increase ◽  
Progressive Increase ◽  
Male Rats ◽  
Metabolic Clearance ◽  
Normal Value ◽  
Plateau Level ◽  
Tsh Levels ◽  
Stimulation Of

ABSTRACT Groups of surgically thyroidectomized (T) male rats were sacrificed at intervals during the period of 1 to 5 and 30 to 180 days after <UNK> Plasma T3, T4 and TSH levels and pituitary TSH content were measured by RIA. A drop of plasma T3 and T4 from normal to undetectable values occurred by day 3 post <UNK>. There was a progressive increase of plasma TSH from the normal value of 136 ± 14 ng/ml to 1623 ± 186 ng/ml (mean ± sem) at day 5 post T, reaching at 30 days a new plateau of 8618 ± 527 ng/ml. These levels remained unchanged up to 130 days post <UNK>. At 180 days, plasma TSH (4123 ± 991 ng/ml) fell significantly below the plateau level. Pituitary TSH content fell from the normal value of 80.9 ± 15.9 μg/mg to a nadir of 12.7 ± 1.4 μg/mg at day 4 post <UNK> and then slowly rose to 98.6 ± 5.9 μg/mg at 100 days, remaining at this level for another 30 days and finally declining significantly at 180 days post <UNK>. The rates of TSH release and synthesis were calculated using the metabolic clearance rates (MCR), determined from the curves of disappearance of injected [125I]-TSH by a non-compartmental analysis. The MCR values decreased, starting at 8 days after T, and reached about half the normal value from 30 days onwards (0.257 ± 0.03 to 0.144 ± 0.001 ml/min/100 g b.w.). The rate of TSH release was increased as early as the first day post <UNK>. A 6-fold increase was reached after 5 days and a new steady state of about 32-fold increase was attained within 1 month. TSH synthesis was also stimulated. However, it lagged behind the stimulation of the release for the first 4 days after <UNK>. The data indicate that: a) The depletion of thyroid hormones affects both synthesis and release of TSH. b) Under prolonged hypothyroidism TSH release and synthesis are in equilibrium, at a markedly enhanced rate. c) Very severe and prolonged hypothyroidism results in a decline in both pituitary and plasma TSH levels.

Plasminogen Activation In Vivo upon Intravenous Infusion of DDAVP

1992 ◽  
Vol 67 (01) ◽  
pp. 111-116 ◽  
Author(s):  
Marcel Levi ◽  
Jan Paul de Boer ◽  
Dorina Roem ◽  
Jan Wouter ten Cate ◽  
C Erik Hack
Keyword(s):  
Monoclonal Antibodies ◽  
Plasminogen Activator ◽  
Plasma Levels ◽  
Fold Increase ◽  
Fibrinolytic System ◽  
Plasminogen Activation ◽  
Plasminogen Activator Activity ◽  
Insight Into

SummaryInfusion of desamino-d-arginine vasopressin (DDAVP) results in an increase in plasma plasminogen activator activity. Whether this increase results in the generation of plasmin in vivo has never been established.A novel sensitive radioimmunoassay (RIA) for the measurement of the complex between plasmin and its main inhibitor α2 antiplasmin (PAP complex) was developed using monoclonal antibodies preferentially reacting with complexed and inactivated α2-antiplasmin and monoclonal antibodies against plasmin. The assay was validated in healthy volunteers and in patients with an activated fibrinolytic system.Infusion of DDAVP in a randomized placebo controlled crossover study resulted in all volunteers in a 6.6-fold increase in PAP complex, which was maximal between 15 and 30 min after the start of the infusion. Hereafter, plasma levels of PAP complex decreased with an apparent half-life of disappearance of about 120 min. Infusion of DDAVP did not induce generation of thrombin, as measured by plasma levels of prothrombin fragment F1+2 and thrombin-antithrombin III (TAT) complex.We conclude that the increase in plasminogen activator activity upon the infusion of DDAVP results in the in vivo generation of plasmin, in the absence of coagulation activation. Studying the DDAVP induced increase in PAP complex of patients with thromboembolic disease and a defective plasminogen activator response upon DDAVP may provide more insight into the role of the fibrinolytic system in the pathogenesis of thrombosis.

Deal–Grove model revisited for a new insight into the oxidation of molten aluminum alloy: The A356 alloy, as a model system

AIChE Journal ◽  
2021 ◽  
Author(s):  
Kévin Patouillet ◽  
Laurent Davoust ◽  
Olivier Doche
Keyword(s):  
Aluminum Alloy ◽  
Molten Aluminum ◽  
A356 Alloy ◽  
Model System ◽  
Molten Aluminum Alloy ◽  
Insight Into

scholarly journals Dengue Virus Induces the Expression and Release of Endocan from Endothelial Cells by an NS1–TLR4-Dependent Mechanism

2021 ◽  
Vol 9 (6) ◽  
pp. 1305
Author(s):  
Carlos Alonso Domínguez-Alemán ◽  
Luis Alberto Sánchez-Vargas ◽  
Karina Guadalupe Hernández-Flores ◽  
Andrea Isabel Torres-Zugaide ◽  
Arturo Reyes-Sandoval ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Mrna Expression ◽  
Cell Lines ◽  
Cell Activation ◽  
Dengue Infection ◽  
Elevated Serum ◽  
Fold Increase ◽  
Endothelial Cell Activation ◽  
Stimulation Of

A common hallmark of dengue infections is the dysfunction of the vascular endothelium induced by different biological mechanisms. In this paper, we studied the role of recombinant NS1 proteins representing the four dengue serotypes, and their role in promoting the expression and release of endocan, which is a highly specific biomarker of endothelial cell activation. We evaluated mRNA expression and the levels of endocan protein in vitro following the stimulation of HUVEC and HMEC-1 cell lines with recombinant NS1 proteins. NS1 proteins increase endocan mRNA expression 48 h post-activation in both endothelial cell lines. Endocan mRNA expression levels were higher in HUVEC and HMEC-1 cells stimulated with NS1 proteins than in non-stimulated cells (p < 0.05). A two-fold to three-fold increase in endocan protein release was observed after the stimulation of HUVECs or HMEC-1 cells with NS1 proteins compared with that in non-stimulated cells (p < 0.05). The blockade of Toll-like receptor 4 (TLR-4) signaling on HMEC-1 cells with an antagonistic antibody prevented NS1-dependent endocan production. Dengue-infected patients showed elevated serum endocan levels (≥30 ng/mL) during early dengue infection. High endocan serum levels were associated with laboratory abnormalities, such as lymphopenia and thrombocytopenia, and are associated with the presence of NS1 in the serum.

Short-term stimulation of the thiazide-sensitive Na+-Cl− cotransporter by vasopressin involves phosphorylation and membrane translocation

2010 ◽  
Vol 298 (3) ◽  
pp. F502-F509 ◽  
Author(s):  
K. Mutig ◽  
T. Saritas ◽  
S. Uchida ◽  
T. Kahl ◽  
T. Borowski ◽  
...  
Keyword(s):  
Fold Increase ◽  
Short Term ◽  
Nephron Segments ◽  
Mediated Effects ◽  
Effector System ◽  
Apical Trafficking ◽  
Fine Regulation ◽  
Combined Action ◽  
Effective Site ◽  
Stimulation Of

Vasopressin influences salt and water transport in renal epithelia. This is coordinated by the combined action of V2 receptor-mediated effects along distinct nephron segments. Modulation of NaCl reabsorption by vasopressin has been established in the loop of Henle, but its role in the distal convoluted tubule (DCT), an effective site for fine regulation of urinary electrolyte composition and the target for thiazide diuretics, is largely unknown. The Na+-Cl− cotransporter (NCC) of DCT is activated by luminal trafficking and phosphorylation at conserved NH2-terminal residues. Here, we demonstrate the effects of short-term vasopressin administration (30 min) on NCC activation in Brattleboro rats with central diabetes insipidus (DI) using the V2 receptor agonist desmopressin (dDAVP). The fraction of NCC abundance in the luminal plasma membrane was significantly increased upon dDAVP as shown by confocal microscopy, immunogold cytochemistry, and Western blot, suggesting increased apical trafficking of the transporter. Changes were paralleled by augmented phosphorylation of NCC as detected by antibodies against phospho-threonine and phospho-serine residues (2.5-fold increase at Thr53 and 1.4-fold increase at Ser71). dDAVP-induced phosphorylation of NCC, studied in tubular suspensions in the absence of systemic effects, was enhanced as well (1.7-fold increase at Ser71), which points to the direct mode of action of vasopressin in DCT. Changes were more pronounced in early (DCT1) than in late DCT as distinguished by the distribution of 11β-hydroxysteroid dehydrogenase 2 in DCT2. These results suggest that the vasopressin-V2 receptor-NCC signaling cascade is a novel effector system to adjust transepithelial NaCl reabsorption in DCT.

Energy nutrients modulate the splanchnic sequestration of dietary nitrogen in humans: a compartmental analysis

2001 ◽  
Vol 281 (2) ◽  
pp. E248-E260 ◽  
Author(s):  
H. Fouillet ◽  
C. Gaudichon ◽  
F. Mariotti ◽  
C. Bos ◽  
J. F. Huneau ◽  
...  
Keyword(s):  
Compartmental Model ◽  
Compartmental Analysis ◽  
Dietary Nitrogen ◽  
Amino Acid Availability ◽  
Nutritional Conditions ◽  
Dietary Amino Acid ◽  
Single Meal ◽  
Peripheral Areas ◽  
Kinetics Of ◽  
Insight Into

We used a previously developed compartmental model to assess the postprandial distribution and metabolism of dietary nitrogen (N) in the splanchnic and peripheral areas after the ingestion of a single meal containing milk protein either alone (MP) or with additional sucrose (SMP) or fat (FMP). The addition of fat was predicted to enhance splanchnic dietary N anabolism only transiently, without significantly affecting the global kinetics of splanchnic retention and peripheral uptake. In contrast, the addition of sucrose, which induced hyperinsulinemia, was predicted to enhance dietary N retention and anabolism in the splanchnic bed, thus leading to reduced peripheral dietary amino acid availability and anabolism. The incorporation of dietary N into splanchnic proteins was thus predicted to reach 18, 24, and 35% of ingested N 8 h after MP, FMP, and SMP, respectively. Such a model provides insight into the dynamics of the system in the nonsteady postprandial state and constitutes a useful, explanatory tool to determine the region-specific utilization of dietary N under different nutritional conditions.

scholarly journals Complex Minisatellite Rearrangements Generated in the Total or Partial Absence of Rad27/hFEN1 Activity Occur in a Single Generation and Are Rad51 and Rad52 Dependent

2006 ◽  
Vol 26 (17) ◽  
pp. 6675-6689 ◽  
Author(s):  
Judith Lopes ◽  
Cyril Ribeyre ◽  
Alain Nicolas
Keyword(s):  
Pedigree Analysis ◽  
Model System ◽  
Yeast Cells ◽  
Single Generation ◽  
Daughter Cells ◽  
Double Deletion ◽  
Mother And Daughter ◽  
Complex Events ◽  
High Degree ◽  
Insight Into

ABSTRACT Genomes contain tandem repeat blocks that are at risk of expansion or contraction. The mechanisms of destabilization of the human minisatellite CEB1 (arrays of 36- to 43-bp repeats) were investigated in a previously developed model system, in which CEB1-0.6 (14 repeats) and CEB1-1.8 (42 repeats) alleles were inserted into the genome of Saccharomyces cerevisiae. As in human cells, CEB1 is stable in mitotically growing yeast cells but is frequently rearranged in the absence of the Rad27/hFEN1 protein involved in Okazaki fragments maturation. To gain insight into this mode of destabilization, the CEB1-1.8 and CEB1-0.6 human alleles and 47 rearrangements derived from a CEB1-1.8 progenitor in rad27Δ cells were sequenced. A high degree of polymorphism of CEB1 internal repeats was observed, attesting to a large variety of homology-driven rearrangements. Simple deletion, double deletion, and highly complex events were observed. Pedigree analysis showed that all rearrangements, even the most complex, occurred in a single generation and were inherited equally by mother and daughter cells. Finally, the rearrangement frequency was found to increase with array size, and partial complementation of the rad27Δ mutation by hFEN1 demonstrated that the production of novel CEB1 alleles is Rad52 and Rad51 dependent. Instability can be explained by an accumulation of unresolved flap structures during replication, leading to the formation of recombinogenic lesions and faulty repair, best understood by homology-dependent synthesis-strand displacement and annealing.

Abstract 1359: Only the Catalytic p110alpha Isoform Mediates Class IA PI 3-Kinase-Induced Atherogenic Signals in Vascular Smooth Muscle Cells

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Marius Vantler ◽  
Lenard Mustafov ◽  
Evren Caglayan ◽  
Stephan Rosenkranz
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Dna Synthesis ◽  
Vascular Smooth Muscle Cells ◽  
Fold Increase ◽  
And Migration ◽  
Induced Apoptosis ◽  
Stimulation Of

Proliferation, migration, and apoptosis of vascular smooth muscle cells (VSMC) are pivotal determinants of the pathogenesis of vascular diseases, which are mainly controlled by growth factor dependent activation of PI 3-Kinase (PI3K). Growth factors like platelet-derived growth factor (PDGF) activate class IA PI3Ks containing one of three p110 catalytic subunits (p110alpha, p110beta, and p110delta). We investigated the specific function of these isoforms for PDGF-controlled proliferation, migration, and apoptosis of VSMC using novel isoform-specific inhibitors. PDGF-dependent proliferation and migration solely depended on p110alpha. Stimulation of VSMC with PDGF-BB (50 ng/ml) mediated a 2.5±0.4 increase ( p <0.05) of DNA-synthesis (BrdU incorporation assay) and induced a 3.4+/−0.7 fold increase ( p <0.05) of VSMC migration (modified Boyden-chamber). Inhibition of p110alpha with PIK075 (1 μ M, Ki=100 nM) completely abrogated PDGF-dependent DNA-synthesis and migration ( p <0,05), whereas inhibitors against p110beta (TGX 221, 1 μ M) or p110delta (IC87114 1 μ M) had no influence. Consistently, PDGF-induced DNA-synthesis and migration were suppressed by siRNA-dependent downregulation of p110alpha ( p <0,05) whereas p110beta or p110delta knockdown had no effect. Interestingly, stimulation of VSMC with PDGF-BB (50 ng/ml) induced anti- or proapoptotic effects depending on the duration of PDGFR activation. Incubation of VSMC with H 2 O 2 (50 μ M, 16h) led to a 2.8±0.7 fold increase ( p >0.05) of apoptosis (Cell Death Detection ELISA). Simultanous addition of PDGF-BB (50 ng/ml) significantly diminished the H 2 O 2 -induced apoptosis (52±7%, p >0.05). In contrast, prestimulation with PDGF-BB 24h prior to the addition of H 2 O 2 led to an increase of H 2 O 2 -induced apoptosis (7.8±1.3, p >0.05). The anti- as well as the proapoptotic effect depended strictly on p110alpha as PIK075 (1 μ M, p <0,05) or p110alpha specific siRNA completely abrogated PDGF-BB-mediated pro- as well as antiapoptotic effects. Our results demonstrate that only the catalytical PI3K subunit p110alpha mediates the growth factor-induced atherogenic responses. Therefore, p110alpha represents an interesting therapeutic target for prevention of atherosclerosis and restenosis formation.

Physiological concentrations of insulin and T3 stimulate 3T3-L1 adipocyte acyl-CoA synthetase gene transcription

1996 ◽  
Vol 270 (5) ◽  
pp. E873-E881 ◽  
Author(s):  
M. S. Kansara ◽  
A. K. Mehra ◽  
J. Von Hagen ◽  
E. Kabotyansky ◽  
P. J. Smith
Keyword(s):  
Gene Transcription ◽  
Fold Increase ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Long Chain Fatty Acids ◽  
Reciprocal Regulation ◽  
Stearoyl Coa Desaturase ◽  
Dose Dependent ◽  
Long Chain ◽  
Stimulation Of

Acyl-CoAsynthetase (ACS) is a key gene for cellular utilization of long-chain fatty acids. We characterized its regulation by physiological concentrations of insulin that acutely regulate metabolism. Our results demonstrate that subnanomolar insulin rapidly and maximally stimulates ACS gene transcription in the absence of protein synthesis; 0.5 nM insulin produced a 2.3 +/- 0.1-fold increase in ACS mRNA levels and induced ACS gene transcription 2.4 +/- 0.3-fold. The insulin sensitivity of ACS was compared with lipoprotein lipase (LPL) and stearoyl-CoA desaturase-1 (SCD-1), which were both less sensitive to insulin. Physiological triiodothyronine (10 nm) also induced ACS mRNA 2.4 +/- 0.1-fold and gene transcription 2.8 +/- 0.3-fold and coordinately induced LPL and SCD-1 mRNA and gene transcription. Because insulin and adenosine 3',5'-cyclic monophosphate often regulate genes involved in lipid and carbohydrate metabolism in a reciprocal manner, we evaluated effects of 1-methyl-3-isobutylxanthine (MIX).ACS mRNA levels were strongly downregulated by MIX in a dose-dependent manner, and ACS gene transcription inhibited in a coordinate manner with LPL and SCD-1. These data demonstrate a uniquely sensitive pattern of stimulation of ACS gene transcription by insulin with reciprocal regulation by MIX, and they suggest a significant role for ACS as a tightly regulated “gatekeeper” gene participating in the control of adipocyte metabolism.

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