scholarly journals The Appearance of a Leptin Effect on Glucose Absorption in Caco2 Cells Depends on Their Differentiation Level

2015 ◽  
Vol 37 (2) ◽  
pp. 491-500 ◽  
Author(s):  
Ola El-Zein ◽  
Julnar Usta ◽  
Sawsan Ibrahim Kreydiyyeh
Keyword(s):  
Intestinal Transport ◽  
Glucose Transporters ◽  
Inhibitory Effect ◽  
Glucose Absorption ◽  
Leptin Receptors ◽  
Transport Studies ◽  
Hormone Effect ◽  
Lower Chamber ◽  
Enzyme Activators ◽  
Upper Chamber

Backdround/Aims: The aim of this work was to study the effect and mechanism of action of leptin added apically, on glucose absorption, using Caco-2 cells as a model. Methods: Cells were grown on inserts and treated with leptin, at different time points after confluence. Radiolabelled glucose was added to the upper chamber and samples from the lower chamber were collected and assayed for radioactivity. Results: Glucose absorption increased with an increase in the level of differentiation and was associated with an increase in the protein expression level of glucose transporters. Leptin reduced glucose absorption only by day 16 after confluence, the time at which apical leptin receptors started appearing. This inhibitory effect became higher the longer the post confluence period, and was prominent on day 23. The hormone effect was found to be mediated via a decrease in the number of glucose transporters (SGLT1 and GLUT2) and a decrease in the activity of the Na+/K+ ATPase which was assayed by measuring the amount of inorganic phosphate liberated in presence and absence of enzyme activators. Conclusion: It was concluded that by day 23 post confluence, Caco-2 cells are differentiated and are appropriate to use as a model for intestinal transport studies.

scholarly journals Diadenosine polyphosphate hydrolase from presynaptic plasma membranes of Torpedo electric organ

1997 ◽  
Vol 323 (3) ◽  
pp. 677-684 ◽  
Author(s):  
Jesús MATEO ◽  
Pedro ROTLLAN ◽  
Eulalia MARTI ◽  
Inmaculada GOMEZ DE ARANDA ◽  
Carles SOLSONA ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Pyridoxal Phosphate ◽  
Electric Organ ◽  
Competitive Inhibitor ◽  
Inhibitory Effect ◽  
Ic50 Value ◽  
Neural Origin ◽  
Disulphonic Acid ◽  
Torpedo Electric Organ ◽  
Enzyme Activators

The diadenosine polyphosphate hydrolase present in presynaptic plasma membranes from the Torpedo electric organ has been characterized using fluorogenic substrates of the form di-(1,N6-ethenoadenosine) 5´,5‴-P1,Pn-polyphosphate. The enzyme hydrolyses diadenosine polyphosphates (Apn A, where n = 3–5), producing AMP and the corresponding adenosine (n-1) 5´-phosphate, Ap(n-1). The Km values of the enzyme were 0.543± 0.015, 0.478±0.043 and 0.520±0.026 μM, and the Vmax values were 633±4, 592±18 and 576±45 pmol/min per mg of protein, for the etheno derivatives of Ap3A (adenosine 5´,5‴-P1,P3-triphosphate), Ap4A (adenosine 5´,5‴-P1,P4 -tetraphosphate) and Ap5A (adenosine 5´,5‴-P1,P5-pentaphosphate) respectively. Ca2+, Mg2+ and Mn2+ are enzyme activators, with EC50 values of 0.86±0.11, 1.35±0.24 and 0.58±0.10 mM respectively. The fluoride ion is an inhibitor with an IC50 value of 1.38±0.19 mM. The ATP analogues adenosine 5´-tetraphosphate and adenosine 5´-[γ-thio]triphosphate are potent competitive inhibitors and adenosine 5´-[α,β-methylene]diphosphate is a less potent competitive inhibitor, the Ki values being 0.29±0.03, 0.43±0.05 and 7.18±0.8 μM respectively. The P2-receptor antagonist pyridoxal phosphate 6-azophenyl-2´,4´-disulphonic acid behaves as a non-competitive inhibitor with a Ki value of 29.7±3.1 μM, and also exhibits a significant inhibitory effect on Torpedo apyrase activity. The effect of pH on the Km and Vmax values, together with inhibition by diethyl pyrocarbonate, strongly suggests the presence of functional histidine residues in Torpedo diadenosine polyphosphate hydrolase. The enzyme from Torpedo shows similarities with that of neural origin from neurochromaffin cells, and significant differences compared with that from endothelial vascular cells.

Regulation of intestinal glucose transport

1992 ◽  
Vol 70 (9) ◽  
pp. 1201-1207 ◽  
Author(s):  
D. J. Philpott ◽  
J. D. Butzner ◽  
J. B. Meddings
Keyword(s):  
Small Intestine ◽  
Glucose Transport ◽  
Intestinal Adaptation ◽  
Basolateral Membrane ◽  
Intestinal Transport ◽  
Glucose Absorption ◽  
Dietary Carbohydrate ◽  
Adaptive Responses ◽  
Carbohydrate Levels ◽  
Specific Regulation

The small intestine is capable of adapting nutrient transport in response to numerous stimuli. This review examines several possible mechanisms involved in intestinal adaptation. In some cases, the enhancement of transport is nonspecific, that is, the absorption of many nutrients is affected. Usually, increased transport capacity in these instances can be attributed to an increase in intestinal surface area. Alternatively, some conditions induce specific regulation at the level of the enterocyte that affects the transport of a particular nutrient. Since the absorption of glucose from the intestine is so well characterized, it serves as a useful model for this type of intestinal adaptation. Four potential sites for the specific regulation of glucose transport have been described, and each is implicated in different situations. First, mechanisms at the brush-border membrane of the enterocyte are believed to be involved in the upregulation of glucose transport that occurs in streptozotocin-induced diabetes mellitus and alterations in dietary carbohydrate levels. Also, factors that increase the sodium gradient across the enterocyte may increase the rate of glucose transport. It has been suggested that an increase in activity of the basolaterally located Na+–K+ ATPase could be responsible for this phenomena. The rapid increase in glucose uptake seen in hyperglycemia seems to be mediated by an increase in both the number and activity of glucose carriers located at the basolateral membrane. More recently, it was demonstrated that mechanisms at the basolateral membrane also play a role in the chronic increase in glucose transport observed when dietary carbohydrate levels are increased. Finally, alterations in tight-junction permeability enhance glucose absorption from the small intestine. The possible signals that prompt these adaptive responses in the small intestine include glucose itself and humoral as well as enteric nervous interactions.Key words: intestinal transport, glucose transport, intestinal adaptation.

Abstract 340: Recombinant Soluble Apyrase Inhibits Vascular Smooth Muscle Cell Migration

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Oluwaseun Adeola ◽  
Yan Ji ◽  
Phillip Fish ◽  
Tammy Strawn ◽  
Gary A Weisman ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Cell Migration ◽  
Endothelial Cell ◽  
Purinergic Receptor ◽  
Neointimal Hyperplasia ◽  
Receptor Activation ◽  
Vehicle Control ◽  
Extracellular Nucleotides ◽  
Lower Chamber ◽  
Upper Chamber

Background: Purinergic receptor activation by extracellular nucleotides is involved in thrombosis and neointimal hyperplasia that accompany atherosclerosis and postangioplasty restenosis. Human apyrases [ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDases)] are membrane bound enzymes that hydrolyze extracellular nucleotides, thereby inhibiting purinergic receptor activation. CD39, the first identified human apyrase, is constitutively expressed on endothelial cell (EC) and vascular smooth muscle cell (VSMC) surfaces. APT102, a recombinant soluble form of CD39L3, has been shown to reduce platelet activation through its ADPase activity, but its effects on VSMC and EC function are yet to be established. We tested the hypothesis that APT102 will inhibit migration of VSMCs and ECs. Methods: We studied cell migration using a modified Boyden chamber assay in which 5x10 4 cells suspended in 0.2% FBS/DMEMF12 were added to the upper chamber of transwells separated from the lower chamber medium by a microporous membrane through which VSMCs and ECs can migrate. APT102 (100 nM) or vehicle control was added to the upper chamber; lower chamber contained 2.5% FBS/DMEMF12 and either ATP (10 μM) or vehicle control. Transwells were incubated at 37 0 C for 6 h, after which cells that migrated through pores and adhered to the lower chamber side of the membrane were fixed, stained and counted. Results: ATP (10μM) significantly enhanced migration of both VSMCs and ECs. APT102 significantly inhibited VSMC migration and completely abrogated the pro-migratory effect of ATP. In contrast, APT102 had no inhibitory effect on EC migration, either spontaneous or ATP-enhanced. Conclusion: APT102 inhibits VSMC but not EC migration. These results suggest that pharmacological targeting of extracellular nucleotides may provide a safe and effective therapeutic strategy to inhibit neointimal hyperplasia and restenosis after angioplasty, without delaying endothelial cell recovery, which is a significant limitation of drug-eluting stents. Further studies are needed to clarify the mechanism(s) underlying the differential effect of extracellular nucleotide degradation by APT102 on VSMC and EC migration.

Sejm Rzeczypospolitej Obojga Narodów 1572–1668

2021 ◽  
Vol 6(167) ◽  
pp. 85-114
Author(s):  
Edward Opaliński
Keyword(s):  
Degradation Process ◽  
Lower Chamber ◽  
First Time ◽  
Upper Chamber ◽  
State Territory ◽  
Chamber Of Deputies

In 1572–1668 the Sejm of the Commonwealth of Two Nations underwent constant evolution. The greatest changes occurred at the time of the first interregnum (1572–74) after the death of the last Jagiellonian monarch – Zygmunt Augustus (1572). This was the time of the emergence of two types of new Sejms (convocation and election ones), functioning exclusively during the interregnum. The Henrician Articles (1574) resolved that the Sejm was to debate only for six weeks, and that the monarch was compelled to convoke it at least once every two years. The extraordinary Sejm was established in 1613 – it could be convened in cases of urgent needs and it sat for two or three weeks. The Parliament was composed of three estates: the king, the Senate, and the deputies as well as two chambers. The upper chamber (Senate) consisted of senators nominated by the monarch on a lifelong basis, and the lower chamber (Chamber of Deputies) – of deputies of the noble estate elected at pre-Sejm sejmiks (Polish: sejmiki). An integral part of the Parliament was composed of the Sejm court, both appellant and trying gravest crimes. The Crown and Lithuanian Tribunal, established in 1578–81, assumed appellation competences from the Sejm court. Tribunal judges were elected every year for a year-long term of office at special sejmiks known as deputational or deputy (judicial), which constituted a forum; here deputies presented to the voters accounts of their parliamentary activity. At the turn of 1591, post-Sejm or relational (debriefing) sejmiks were convened after the closure of the Sejm debates; here deputies presented reports concerning their parliamentary activities. The growing composition of the Parliament was associated with an expansion of state territory as a result of victorious wars waged against Muscovy. New bishoprics, voivodeships, and sejmiki were established. There were 140 senators in 1572, and 150 during the 1630s. Analogously, the number of deputies grew from 166 to 180. The Sejm acted upon the basis of a consensus, and thus was obligated to take into account the stand of the minorities. In 1652, the protest of a single deputy for the first time rendered further Sejm debates impossible. From then on, the Polish-Lithuanian Parliament constantly succumbed to a degradation process.

Isolated membrane vesicles as tools for analysis of epithelial transport.

1977 ◽  
Vol 233 (6) ◽  
pp. E445
Author(s):  
U Hopfer
Keyword(s):  
Amino Acid ◽  
Brush Border ◽  
Plasma Membranes ◽  
Brush Border Membrane ◽  
Epithelial Transport ◽  
Intestinal Transport ◽  
Membrane Vesicles ◽  
Transport Studies ◽  
Glucose Transport System ◽  
Equilibrium Exchange

In recent years a methodology has been developed to use vesicles of the isolated brush border and basolateral plasma membranes for intestinal transport studies. The methodology and information gained with the vesicle systems are discussed using the examples of nonelectrolyte transport. In particular, results are presented on the mechanisms of D-glucose and neutral amino acid translocation across both plasma membranes and the coupling of Na+ with sugar and amino acid transport in the brush-border membrane. Furthermore, the kinetic parameters of the Na+-dependent glucose transport system, determined with an equilibrium exchange procedure, and the effects of semistarvation on the transport properties of the brush border membrane are described.

scholarly journals Monocyte Proteomics Reveals Involvement of Phosphorylated HSP27 in the Pathogenesis of Osteoporosis

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Bhavna Daswani ◽  
Manoj Kumar Gupta ◽  
Shubhangi Gavali ◽  
Meena Desai ◽  
Gajanan J. Sathe ◽  
...  
Keyword(s):  
Absolute Quantification ◽  
Osteoclast Formation ◽  
Mineral Density ◽  
Monocyte Migration ◽  
Receptor Activator ◽  
Lower Chamber ◽  
Isobaric Tags ◽  
First Time ◽  
Upper Chamber ◽  
Increased Susceptibility

Peripheral monocytes, precursors of osteoclasts, have emerged as important candidates for identifying proteins relevant to osteoporosis, a condition characterized by low Bone Mineral Density (BMD) and increased susceptibility for fractures. We employed 4-plex iTRAQ (isobaric tags for relative and absolute quantification) coupled with LC-MS/MS (liquid chromatography coupled with tandem mass spectrometry) to identify differentially expressed monocyte proteins from premenopausal and postmenopausal women with low versus high BMD. Of 1801 proteins identified, 45 were differentially abundant in low versus high BMD, with heat shock protein 27 (HSP27) distinctly upregulated in low BMD condition in both premenopausal and postmenopausal categories. Validation in individual samples (n=80) using intracellular ELISA confirmed that total HSP27 (tHSP27) as well as phosphorylated HSP27 (pHSP27) was elevated in low BMD condition in both categories (P<0.05). Further, using transwell assays, pHSP27, when placed in the upper chamber, could increase monocyte migration (P<0.0001) and this was additive in combination with RANKL (receptor activator ofNFkBligand) placed in the lower chamber (P=0.05). Effect of pHSP27 in monocyte migration towards bone milieu can result in increased osteoclast formation and thus contribute to pathogenesis of osteoporosis. Overall, this study reveals for the first time a novel link between monocyte HSP27 and BMD.

scholarly journals Inhibition of α-Glucosidase, Intestinal Glucose Absorption, and Antidiabetic Properties by Caralluma europaea

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Hayat Ouassou ◽  
Touda Zahidi ◽  
Saliha Bouknana ◽  
Mohamed Bouhrim ◽  
Hassane Mekhfi ◽  
...  
Keyword(s):  
Ethyl Acetate Fraction ◽  
Inhibitory Effect ◽  
Tolerance Test ◽  
Glucose Absorption ◽  
Significant Inhibition ◽  
Oral Glucose ◽  
Glucosidase Activity ◽  
Intestinal Glucose Absorption

Many medicinal plants around the world are used for therapeutic purposes against several diseases, including diabetes mellitus. Due to their composition of natural substances that are effective and do not represent side effects for users, unlike synthetic drugs, in this study, we investigated the inhibitory effect of Caralluma europaea (CE) on α-glucosidase activity in vitro; then the kinetics of the enzyme were studied with increasing concentrations of sucrose in order to determine the inhibition type of the enzyme. In addition, this effect of Caralluma europaea (CE) was confirmed in vivo using rats as an experimental animal model. Among the five fractions of CE, only the ethyl acetate fraction of C. europaea (EACe) induced a significant inhibition of α-glucosidase and its inhibition mode was competitive. The in vivo studies were conducted on mice and rats using glucose and sucrose as a substrate, respectively, to determine the oral glucose tolerance test (OGTT). The results obtained showed that the EACe and the aqueous extract of C. europaea (AECe) have significantly reduced the postprandial hyperglycemia after sucrose and glucose loading in normal and diabetic rats. AECe, also, significantly decreased intestinal glucose absorption, in situ. The results obtained showed that Caralluma europaea has a significant antihyperglycemic activity, which could be due to the inhibition of α-glucosidase activity and enteric absorption of glucose.

Inhibitory effect of roasted/ unroasted Argania spinosa seeds oil on α- glucosidase, α-amylase and intestinal glucose absorption activities

2020 ◽  
Vol 135 ◽  
pp. 413-420
Author(s):  
Nour Elhouda Daoudi ◽  
Mohamed Bouhrim ◽  
Hayat Ouassou ◽  
Abdelkhaleq Legssyer ◽  
Hassane Mekhfi ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Glucose Absorption ◽  
Argania Spinosa ◽  
Intestinal Glucose Absorption

Ionic effect on intestinal transport of glucose in the rat

1960 ◽  
Vol 198 (5) ◽  
pp. 1056-1058 ◽  
Author(s):  
T. Z. Csáky ◽  
Lawrence Zollicoffer
Keyword(s):  
Glucose Transport ◽  
Intestinal Transport ◽  
Glucose Absorption ◽  
Anesthetized Rats ◽  
Ionic Effect

A loop of upper jejunum of anesthetized rats was perfused in situ with glucose (500 mg/l.) dissolved in either isosmotic Na2SO4, Li2SO4, K2SO4 or MgSO4. Rapid glucose absorption takes place from the Na2SO4 solution, whereas the glucose transport is inhibited if Na is replaced. The rate of inhibition varied: 91% with Li, 86% with K and 75% with Mg. The inhibition is reversible by the subsequent perfusion of the same gut with Na2SO4.

scholarly journals Inhibitory effect of leptin on the rat ovary during the ovulatory process

Reproduction ◽  
2006 ◽  
Vol 132 (5) ◽  
pp. 771-780 ◽  
Author(s):  
A G Ricci ◽  
M P Di Yorio ◽  
A G Faletti
Keyword(s):  
Leptin Receptor ◽  
Inhibitory Effect ◽  
Chorionic Gonadotrophin ◽  
Prostaglandin E ◽  
Negative Effects ◽  
Serum Progesterone ◽  
Leptin Receptors ◽  
The Media ◽  
Ovulatory Process

The aims of this study were to investigate the negative action of leptin on some intraovarian ovulatory mediators during the ovulatory process and to assess whether leptin is able to alter the expression of its ovarian receptors. Immature rats primed with gonadotrophins were used to induce ovulation. Serum leptin concentration was diminished 4 h after human chorionic gonadotrophin (hCG) administration, whereas the ovarian expression of leptin receptors, measured by western blot, was increased by the gonadotrophin treatment. Serum progesterone level, ovulation rate and ovarian prostaglandin E (PGE) content were reduced in rats primed with equine chorionic gonadotrophin (eCG)/hCG and treated with acute doses of leptin (five doses of 5 μg each). These inhibitory effects were confirmed by in vitro studies, where the presence of leptin reduced the concentrations of progesterone, PGE and nitrites in the media of both ovarian explants and preovulatory follicle cultures. We also investigated whether these negative effects were mediated by changes in the expression of the ovarian leptin receptors. Since leptin treatment did not alter the expression of ovarian leptin receptor, the inhibitory effect of leptin on the ovulatory process may not be mediated by changes in the expression of its receptors at ovarian level, at least at the concentrations assayed. In summary, the ovulatory process was significantly inhibited in response to an acute treatment with leptin, and this effect may be due, at least in part, to the direct or indirect impairment of some ovarian factors, such as prostaglandins and nitric oxide.

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