354 results on '"S. Chemtob"'
Search Results
2. 'CD36 plays an important role in the clearance of oxLDL and associated age-dependent sub-retinal deposits.'
- Author
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Picard, E, M. Houssier, K. Bujold, P. Sapieha, W. Lubell, A. Dorfman, J. Racine, P. Hardy, M. Febbraio, P. Lachapelle, H. Ong, F. Sennlaub and S. Chemtob, Picard, E., M. Houssier, K. Bujold, P. Sapieha, W. Lubell, A. Dorfman, J. Racine, P. Hardy, M. Febbraio, P. Lachapelle, H. Ong, F. Sennlaub, and S. Chemtob
- Published
- 2010
3. Vessel remodeling in the newborn: platelets fill the gap
- Author
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Ronald I. Clyman and S. Chemtob
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medicine.medical_specialty ,Aorta ,Platelet aggregation ,business.industry ,General Medicine ,General Biochemistry, Genetics and Molecular Biology ,Main Pulmonary Artery ,medicine.anatomical_structure ,Internal medicine ,medicine.artery ,Circulatory system ,medicine ,Cardiology ,Platelet ,business ,Blood vessel - Abstract
In newborn infants, permanent closure of a major blood vessel connecting the main pulmonary artery to the aorta is essential to allow adequate circulation of blood to major organs. Platelet aggregation now emerges as a crucial step in this process in newborn mice and, possibly, in preterm infants (pages 75–82).
- Published
- 2010
4. Deficiency in the metabolite receptor SUCNR1 (GPR91) leads to outer retinal lesions
- Author
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Favret, S. Binet, F. Lapalme, E. Leboeuf, D. Carbadillo, J. Rubic, T. Picard, E. Mawambo, G. Tetreault, N. Joyal, J. S. Chemtob, S. Sennlaub, F. Sangiovanni, J. P. Guimond, and M. Sapieha
- Published
- 2013
5. Ontogenic increase in PGE2 and PGF2α receptor density in brain microvessels of pigs
- Author
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Ding-You Li, Daya R. Varma, and S. Chemtob
- Subjects
Agonist ,medicine.medical_specialty ,Swine ,medicine.drug_class ,Prostaglandin E2 receptor ,Receptors, Prostaglandin ,Alpha (ethology) ,Stimulation ,Biology ,Dinoprost ,Ligands ,Dinoprostone ,Internal medicine ,Cyclic AMP ,medicine ,Animals ,Inosine Triphosphate ,Receptors, Prostaglandin E ,Prostaglandin E2 ,Receptor ,Brain Chemistry ,Pharmacology ,Antagonist ,Brain ,Adenosine ,Capillaries ,Kinetics ,Endocrinology ,Animals, Newborn ,cardiovascular system ,lipids (amino acids, peptides, and proteins) ,Research Article ,medicine.drug - Abstract
1. The hypothesis that the relative vasoconstrictor ineffectiveness of prostaglandin E2 (PGE2) and PGF2 alpha on cerebral vessels of newborn pigs might be due to fewer receptors for these prostanoids was tested by comparing receptors for PGE2 (EP) and PGF2 alpha (FP) in cerebral microvessels from newborn and adult pigs. 2. Specific binding of [3H]-PGE2 and [3H]-PGF2 alpha to membranes prepared from brain microvessels showed that EP and FP receptor density (Bmax) in tissues from newborn animals was less than 50% of that determined in tissues from adults. By contrast, estimates of affinity (KD) were unchanged. 3. Specifically bound [3H]-PGE2 to brain microvessels from both the newborn and adult was displaced by AH 6809 (EP1-selective antagonist) by 80-90%, and only by approximately 30-35% by both 11-deoxy PGE1 (EP2/EP3 agonist) and MB 28,767 (EP3 agonist); butaprost (EP2 agonist) was completely ineffective. 4. PGE2, 17-phenyl trinor PGE2 (EP1 agonist), PGF2 alpha and fenprostalene (PGF2 alpha analogue) caused significantly less increase in inositol 1,4,5-triphosphate (IP3) in brain microvessels from the newborn than in those from adult pigs. The stimulation of IP3 by PGE2 and 17-phenyl trinor PGE2 was almost completely inhibited by the EP1 antagonist, AH 6809. 5. PGE2, 11-deoxy PGE1 and MB 28,767 produced small reduction of adenosine 3':5'-cyclic monophosphate (cyclic AMP) production in adult vessels but no effect in newborn tissues. 6. The lower density of EP and FP receptors in microvessels of newborn pigs compared to adults may explain the reduced ability of PGE2 and PGF2 alpha to stimulate production of IP3 in tissues from newborn animals. This in turn, may provide an explanation for previous observations demonstrating that these prostanoids elicit contraction of adult cerebral microvessels, but exert minimal effects on these vessels in newborn animals.
- Published
- 1994
6. [Epidemiology and pathophysiology of retinopathy of prematurity]
- Author
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E, Kermorvant-Duchemin, F, Sennlaub, F, Behar-Cohen, and S, Chemtob
- Subjects
Vascular Endothelial Growth Factor A ,Oxidative Stress ,Infant, Newborn ,Oxygen Inhalation Therapy ,Humans ,Retinopathy of Prematurity ,Insulin-Like Growth Factor I ,Retinal Neovascularization ,Reactive Oxygen Species - Abstract
Retinopathy of prematurity (ROP) is a major cause of visual impairment in premature infants. It is characterized by an arrest in normal retinal vascular development associated with microvascular degeneration, followed by an abnormal hypoxiainduced neovascularization. Recent studies point out that ROP is a multifactorial disease, implicating both oxygen-dependent and oxygen-independent mechanisms. Oxygen-dependent factors leading to microvascular degeneration include generation of reactive oxygen species and suppression of specific oxygen-regulated vascular survival factors, such as vascular endothelial growth factor (VEGF) and erythropoietin. The other major mechanism for the initial capillary loss is oxygen-independent and implicates a deficit in growth factor IGF-1/IGFBP3. The proliferative, second phase of ROP is triggered by increases in vascular growth factors concentrations, in an attempt to compensate for the hypoxic retina. Novel signaling pathways for vascular repair, implicating both metabolite signaling and inflammatory lipids signaling, represent new therapeutic avenues for ROP.
- Published
- 2011
7. A convenient alternative approach to screen for retinopathy of prematurity
- Author
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S. Chemtob
- Subjects
Pediatrics ,medicine.medical_specialty ,business.industry ,Infant, Newborn ,Retinal Vessels ,Retinopathy of prematurity ,General Medicine ,medicine.disease ,Eye ,Insulin-Like Growth Factor Binding Proteins ,Ophthalmoscopy ,Insulin-Like Growth Factor Binding Protein 3 ,Neonatal Screening ,Pediatrics, Perinatology and Child Health ,medicine ,Humans ,Retinopathy of Prematurity ,Insulin-Like Growth Factor I ,business ,Infant, Premature - Published
- 2010
8. Exploring the relationship between turn geometry and allosteric antagonism of peptide mimic ligands for the prostaglandin F2alpha receptor
- Author
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C B, Bourguet, X, Hou, S, Chemtob, and W D, Lubell
- Subjects
Allosteric Regulation ,Molecular Mimicry ,Receptors, Prostaglandin ,Ligands ,Peptides - Published
- 2009
9. Prostanoids determine the range of cerebral blood flow autoregulation of newborn piglets
- Author
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J Rex, S. Chemtob, D R Varma, K Beharry, and Jacob V. Aranda
- Subjects
Prostaglandin Antagonists ,Swine ,Thromboxane ,medicine.medical_treatment ,Prostaglandin ,Hemodynamics ,Blood Pressure ,Ibuprofen ,chemistry.chemical_compound ,Animals ,Homeostasis ,Medicine ,Advanced and Specialized Nursing ,business.industry ,Osmolar Concentration ,Prostanoid ,Microspheres ,Thromboxane B2 ,Blood pressure ,Animals, Newborn ,chemistry ,Cerebral blood flow ,Cerebrovascular Circulation ,Anesthesia ,Prostaglandins ,Vascular Resistance ,Neurology (clinical) ,Cardiology and Cardiovascular Medicine ,business ,Prostaglandin E - Abstract
To assess whether prostanoids have a role in setting the blood pressure limits of cerebral blood flow autoregulation in newborn animals, we measured cerebral blood flow and prostanoid concentrations in blood from the sagittal sinus over a wide range of mean systemic blood pressures (17-117 mm Hg) in eight newborn piglets treated with 30 mg/kg i.v. ibuprofen and in eight vehicle-treated piglets. Blood pressure was adjusted by inflating balloon-tipped catheters placed at the aortic isthmus and root to induce hypertension and hypotension, respectively, 80 minutes apart in each piglet. Cerebral blood flow and concentrations of prostaglandins E and F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2 in blood from the sagittal sinus and left subclavian artery were measured 20 minutes before (baseline) and during each blood pressure adjustment. In vehicle-treated piglets, cerebral blood flow was constant at blood pressures between 50 and 90 mm Hg (r = 0.06, p = 0.85). When blood pressure was reduced to less than 50 mm Hg, thromboxane B2 concentration in the sagittal sinus increased by 597 +/- 42% and concentrations of the prostaglandins increased by an average of 308 +/- 45% (p less than 0.05). When blood pressure was raised to greater than 90 mm Hg, concentrations of the prostaglandins increased by an average of 46 +/- 11%, with no change in the concentration of thromboxane B2. Treatment with ibuprofen reduced the baseline concentrations of all prostanoids and prevented their changing during hypotension and hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1990
10. [Pathophysiology of retinopathy of prematurity]
- Author
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E, Kermorvant-Duchemin, F, Sennlaub, S, Chemtob, and F, Behar-Cohen
- Subjects
Oxygen ,Vascular Endothelial Growth Factor A ,Oxidative Stress ,Eicosanoic Acids ,Retinal Artery Occlusion ,Infant, Newborn ,Humans ,Retinal Vessels ,Retinopathy of Prematurity ,Stereoisomerism ,Endothelium, Vascular ,Reactive Nitrogen Species - Published
- 2006
11. 350 Sorting Nexin-30: A New Negative Regulator of Wnt/β-Catenin Signaling Identified in the Frog With Implications in Cardiogenesis
- Author
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N. Dubois, Severine Leclerc, S. Chemtob, Gregor Andelfinger, and M. Cameron
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Sorting nexin ,business.industry ,Wnt β catenin signaling ,Medicine ,Anatomy ,Cardiology and Cardiovascular Medicine ,business ,Negative regulator ,Cell biology - Published
- 2012
12. Generation of reactive O2 species in the myocardium of newborn lambs following intrauterine increase in right ventricular pressure
- Author
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P. Haswani, Pierre Russo, S. Castor, Amanda Skoll, Claude Chartrand, S. Chemtob, Sven-Erik Sonesson, Teyssier G, and Jean-Claude Fouron
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medicine.medical_specialty ,Context (language use) ,Constriction ,Fetus ,Pregnancy ,Internal medicine ,Ductus arteriosus ,medicine ,Ventricular Pressure ,Animals ,Sheep ,business.industry ,Myocardium ,Cardiac surgery ,medicine.anatomical_structure ,Animals, Newborn ,Ventricle ,Pediatrics, Perinatology and Child Health ,cardiovascular system ,Cardiology ,Ventricular pressure ,Ventricular Function, Right ,Gestation ,Female ,Cardiology and Cardiovascular Medicine ,business ,Reactive Oxygen Species - Abstract
Fetuses with pulmonary stenosis and constriction of the ductus arteriosus or the recipient twin in the context of a twin-to-twin transfusion syndrome may present with severe right ventricular myocardial dysfunction. Free O2 radicals are known to be increased in hypertrophied adult myocardium secondary to an increase in endocavitary pressure. This study investigates whether products of reactive O2 species generation are abnormally elevated in the myocardium of fetuses with increased right ventricular pressure. Banding of the main pulmonary artery was performed in five fetal lambs at 90 to 100 days of gestation. Three other animals had a sham intervention and were used as controls. Postoperative observation lasted on average 42 days (range 33-49 days). The levels of hydroperoxides were found to be significantly higher in the right ventricle of the stenosed lambs (6.6 +/- 3.5 nmol/mg protein) compared to the left ventricle of the same lambs (0.7 +/- 0.7 nmol/mg protein), and compared to the right (0.12 +/- 0.1 nmol/mg protein) and the left (0.5 +/- 0.8 nmol/mg protein) ventricles of the controls. It is concluded that during fetal life, an increase in right ventricular pressure is associated with a marked accumulation of products of reactive O2 species generation in the right ventricular myocardium.
- Published
- 2001
13. Distribution of alpha1-adrenoceptor subtype proteins in different tissues of neonatal and adult rats
- Author
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H, Shen, K G, Peri, X F, Deng, S, Chemtob, and D R, Varma
- Subjects
Male ,Rats, Sprague-Dawley ,Animals, Newborn ,Antibody Specificity ,Receptors, Adrenergic, alpha-1 ,Blotting, Western ,Age Factors ,Animals ,Rats - Abstract
Distribution of alpha(1)-adrenoceptor (alpha(1)AR) subtype (alpha(1A), alpha(1B), alpha(1D)) proteins in brain, heart, kidney, and liver of 1-week-old rats and in brain, heart, aorta, kidney, liver, vas deferens, prostate, and adrenal glands of adult rats was investigated by Western analysis, using receptor subtype specific polyclonal antibodies. High levels of immunoreactive alpha(1A)AR and alpha(1D)AR in brain and heart and of alpha(1B)AR in liver and heart of neonatal rats were detected. In adult rat tissues, the abundance of alpha(1A)AR protein was most marked in the brain, intermediate in heart, aorta, liver, vas deferens, and adrenals, and minimal in the kidney and prostate; relative to other tissues, the expression of alpha(1B)AR was higher in brain and heart and that of alpha(1D)AR in brain. All the three receptor subtypes increased with age in the brain cortex, whereas the abundance of alpha(1B)AR increased in the heart but decreased in the liver; alpha(1A)AR and alpha(1D)AR in liver, kidney, and heart were not affected by age. It is concluded that alpha(1)AR subtypes are widely expressed in different neonatal and adult rat tissues.
- Published
- 2000
14. Developmental regulation of endothelial nitric oxide synthase in cerebral vessels of newborn pig by prostaglandin E(2)
- Author
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I, Dumont, X, Hou, P, Hardy, K G, Peri, M, Beauchamp, T, Najarian, S, Molotchnikoff, D R, Varma, and S, Chemtob
- Subjects
Dose-Response Relationship, Drug ,Swine ,Blotting, Western ,Age Factors ,NADPH Dehydrogenase ,Ibuprofen ,Nitric Oxide ,Dinoprostone ,Capillaries ,Animals, Newborn ,Cerebellum ,Prostaglandins ,Animals ,Drug Interactions ,Endothelium, Vascular ,RNA, Messenger ,Nitric Oxide Synthase ,Nitrites - Abstract
We investigated whether prostaglandins regulate endothelial nitric oxide synthase (eNOS) in the pig cerebral vasculature during the neonatal period. Prostaglandins, eNOS mRNA, eNOS protein, and NO production were higher in cerebral microvessels of newborn (1 day old) than in those of adult (6- to 8-month-old) pigs. The treatment of isolated cerebral microvessels of newborn animals with ibuprofen for 24 h reduced eNOS mRNA and nitrite production to levels in the adult; this effect of ibuprofen was prevented by concurrent treatment with prostaglandin (PG)E(2) analog 16,16-dimethyl-PGE(2), nonselective PGE(2) receptor analog 11-deoxy PGE(1), and prostaglandin EP(3) receptor agonists sulprostone and MB 28,767 but was not modified by PGI(2) analog carbaprostacyclin, PGD(2), and EP(1) receptor agonist 17-phenyl trinor PGE(2). Correspondingly, 16, 16-dimethyl-PGE(2) and MB 28,767 increased eNOS mRNA expression of adult microvessels to values in the newborn. Data similar to those with isolated cerebral vessels were obtained through histochemical analysis (NADPH-diaphorase positivity) of brain from newborn animals treated in vivo with ibuprofen in combination or not with sulprostone. Furthermore, substance P-induced NO-mediated cerebral vasorelaxation was decreased to adult values through the treatment of newborn pigs with ibuprofen; this effect was prevented by concomitant treatment with sulprostone. It is concluded that PGE(2) regulates eNOS in newborn pig cerebral microvessels via EP(3) receptors; this may be physiologically required during normal neurovascular development.
- Published
- 1999
15. Inverse agonist activities of beta-adrenoceptor antagonists in rat myocardium
- Author
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D R, Varma, H, Shen, X F, Deng, K G, Peri, S, Chemtob, and S, Mulay
- Subjects
Male ,Adrenergic beta-Antagonists ,Blotting, Western ,Isoproterenol ,Adrenergic beta-Agonists ,In Vitro Techniques ,Myocardial Contraction ,Rats ,Propanolamines ,Rats, Sprague-Dawley ,Pindolol ,Papers ,cardiovascular system ,Animals ,Albuterol ,Receptors, Adrenergic, beta-2 ,Receptors, Adrenergic, beta-1 - Abstract
1. Negative inotropic effects of several beta-adrenoceptor (betaAR) antagonists on electrically-stimulated right atria, left atria, right ventricles and left ventricular papillary muscles from reserpine-treated rats were used as a measure of their inverse agonist activities. 2. Beta1AR antagonists acebutolol, atenolol and metoprolol, beta2AR antagonist ICI-181,551 and nonselective betaAR antagonists alprenolol, nadolol, propranolol and timolol produced negative inotropic effects, which were most marked on the right atria. 3. The nonselective betaAR antagonist pindolol did not exhibit inverse agonist activity but inhibited the negative inotropic activities of ICI-118,551, atenolol and propranolol. 4. The negative inotropic effects of lidocaine, nifedipine and pentobarbitone were similar on all the four myocardial preparations. 5. The positive inotropic efficacy of salbutamol on right and left atria but not on right ventricles and papillary muscles was comparable to that of isoprenaline. The antagonist activity of ICI-118,551 against isoprenaline was greater on right atria than on other cardiac regions. 6. Beta1AR proteins were expressed in all regions of the heart but of beta2AR were primarily localized in the right atrium. 7. It is concluded that beta2AR play a greater role in right atria than in other cardiac regions and almost all betaAR antagonists behave as inverse agonists.
- Published
- 1999
16. Increases in retinovascular prostaglandin receptor functions by cyclooxygenase-1 and -2 inhibition
- Author
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P, Hardy, M, Bhattacharya, D, Abran, K G, Peri, P, Asselin, D R, Varma, S, Chemtob, and M, Bhatthacharya
- Subjects
Cyclooxygenase 2 Inhibitors ,Swine ,Prostaglandins E ,Receptors, Prostaglandin ,Down-Regulation ,Retinal Vessels ,Inositol 1,4,5-Trisphosphate ,Isoenzymes ,Animals, Newborn ,Cyclooxygenase 2 ,Prostaglandin-Endoperoxide Synthases ,Vasoconstriction ,Cyclic AMP ,Cyclooxygenase 1 ,Animals ,Homeostasis ,Receptors, Prostaglandin E ,Cyclooxygenase Inhibitors ,Blood Flow Velocity - Abstract
To determine the relative contribution of cyclooxygenase (COX)-1 and COX-2 in regulating prostaglandin (PG) E2 and PGF2alpha receptors (EP and FP, respectively) densities and their functions in retinal vasculature of neonatal pigs.Newborn pigs were treated intravenously every 8 hours for 48 hours with saline, 40 mg/kg nonselective COX inhibitor ibuprofen, 80 mg/kg COX-1 inhibitor valeryl salicylate, or 5 mg/kg DuP697 and 5 mg/kg NS398, COX-2 inhibitors. Retinal microvessel EP and FP receptor densities were measured by radioligand binding and receptor-coupled effects by determining second-messenger inositol 1,4,5-trisphosphate (IP3) and vasomotor responses. Retinal blood flow (RBF) response to incremental increases in blood pressure (BP) was measured by a microsphere technique.Valeryl salicylate, DuP697, and NS398 reduced retinal PGE2 and PGF2alpha concentrations in the newborn by approximately half, whereas ibuprofen caused further reduction to levels observed in adults. Retinal vessel EP1, EP3, and FP receptor densities increased approximately threefold after treatments with COX-1 or COX-2 inhibitors, and five- to sixfold after ibuprofen treatment. EP and FP receptor upregulation was associated with corresponding increases in IP3 production and retinal vasoconstriction in response to PGF2alpha, fenprostalene (an FP agonist), PGE2, 17-phenyl trinor PGE2 (an EP1 agonist), and MB28,767 (an EP3 agonist) and with enhanced RBF autoregulation of high BP (or =125 mm Hg). Conversely, EP2 receptor density and coupled functions were minimally affected by COX inhibition.Data suggest that increased COX-1- and COX-2-catalyzed prostaglandin synthesis contribute equivalently to the downregulation of retinovascular EP1, EP3, and FP receptors and their vasoconstrictor functions in newborn pigs; the EP2 receptor was not significantly influenced by ontogenic alterations in prostaglandin levels.
- Published
- 1998
17. Crosstalk between alpha-1A and alpha-1B adrenoceptors in neonatal rat myocardium: implications in cardiac hypertrophy
- Author
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X F, Deng, A, Sculptoreanu, S, Mulay, K G, Peri, J F, Li, W H, Zheng, S, Chemtob, and D R, Varma
- Subjects
Tetrahydronaphthalenes ,Imidazoles ,Cardiomegaly ,Heart ,Myocardial Contraction ,Rats ,Isoenzymes ,Phenylephrine ,Animals, Newborn ,Receptors, Adrenergic, alpha-1 ,Animals ,Calcium ,Calcium Channels ,Protein Kinase C - Abstract
The myocardial effect of alpha-1A adrenoceptor (alpha-1 AR) agonists in neonatal rats are mediated by alpha-1A AR and not by alpha-1B AR, although both receptor subtypes are equally expressed; the functions of alpha-1B AR are not known. Here, we report that alpha-1 B ARs inhibit the activities of alpha-1A ARs in neonatal rat myocardium so that the inactivation of alpha-1 B ARs by chloroethylclonidine (CEC) potentiated the effects of nonselective alpha-1 AR agonist phenylephrine (PE) on myocardial protein synthesis and early gene (c-fos and c-jun) expression. CEC did not modify the hypertrophic effect of angiotensin II. The potentiation of the effects of PE by CEC was associated with a translocation of Ca(++)-dependent protein kinase C (PKC)alpha, which did not occur in the absence of CEC. Alpha-1A AR-selective agonist A61603 was approximately 1000-fold more potent than PE as a positive inotropic agent; it caused the translocation of PKC alpha, which was not affected by CEC. 5-Methylurapidil antagonized the effects of PE and A61603, suggesting that these were mediated via alpha-1A ARs. Alpha-1D AR antagonist BMY 7378 did not modify PE-induced translocation of PKC. CEC potentiated the effects of PE on Ca++ transients in Fura 2-AM-loaded dispersed cardiomyocytes, and this potentiation was prevented by nifedipine. In whole-cell patch-clamp recordings of cultured cardiomyocytes, CEC potentiated the effect of norepinephrine on Ca++ channel currents, which was blocked by 5-methylurapidil. We conclude that alpha-1A ARs are positively and alpha-1B ARs are negatively coupled to nifedipine-sensitive Ca++ channels, possibly via Gi protein, and this antagonistic relationship between alpha-A AR and alpha-1B AR in the neonatal heart might be required physiologically for normal alpha-1 AR-mediated responses and myocardial development.
- Published
- 1998
18. Enhancing the flexibility and adaptability of the DARC structural representation for computer-aided drug design
- Author
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C. Mercier, Y. Sobel, F. Barbieux, P. Vizet, and S. Chemtob
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Quantitative structure–activity relationship ,Chemical Phenomena ,Property (programming) ,media_common.quotation_subject ,Population ,Bioengineering ,computer.software_genre ,Adaptability ,Structural representation ,Structure-Activity Relationship ,Computational chemistry ,Drug Discovery ,Animals ,Humans ,education ,Topology (chemistry) ,media_common ,Flexibility (engineering) ,education.field_of_study ,Chemistry ,Chemistry, Physical ,General Medicine ,Drug Design ,Computer-aided ,Molecular Medicine ,Computer-Aided Design ,Data mining ,computer - Abstract
Noticeable progress has been achieved in the determination of dynamic topochromatic variables for the structural representation of compounds and their situation in a given population. These independent structural variables can be further combined into more complex variables. Their contributions to the evolution of an associated property can therefore be evaluated with certainty. The risk of having correlated variables is avoided while the structural description remains exhaustive. In order to enhance the interpretative ability of the QSAR model, one or several physicochemical properties can be taken with these structural parameters as explanatory variables. Typically, partition coefficients, 3-D and quantum mechanical data are used for this purpose. The structural aspects not taken into account by the physicochemical parameters are reflected in the remaining topochromatic variables. The use of these new concepts is presented in a study of carbazole mutagenicity. The model explains 99% of the total variance with one external property and four additional topochromatic variables. The modulation of the heat of formation of an intermediate by two topochromatic variables suggests a much more precise interpretation than a simple combination of the usual external variables.
- Published
- 1998
19. Mechanisms of the atrium-specific positive inotropic activities of quinidine- and atropine-like agents in rats
- Author
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X F, Deng, S, Mulay, S, Chemtob, and D R, Varma
- Subjects
Atropine ,Male ,Isoproterenol ,Receptors, Nicotinic ,Bupivacaine ,Myocardial Contraction ,Propranolol ,Quinidine ,Stimulation, Chemical ,Rats ,Rats, Sprague-Dawley ,Catecholamines ,Animals ,Heart Atria ,Dimethylphenylpiperazinium Iodide ,Anti-Arrhythmia Agents ,Disopyramide - Abstract
This study investigated the mechanism of the positive inotropic effects of class 1 antiarrhythmic agents using electrically stimulated right atria (sinoatrial node excised), left atria and right ventricles of rats. Quinidine, disopyramide and procainamide produced concentration-dependent positive inotropic effects on right and left atria; effects on the right atria were greater than on left atria. At concentration producing positive inotropic effects on atria, the contractions of right ventricles were slightly increased by quinidine, unaffected by disopyramide and decreased by procainamide. The positive inotropic effects of quinidine were inhibited by propranolol, reserpine and mecamylamine but not by cocaine, hexamethonium and d-tubocurarine; propranolol also antagonized the positive inotropic effects of disopyramide and procainamide. Bupivacaine, which like quinidine blocks transient outward potassium current, slightly increased the contractions of right atria but not of left atria and ventricles. The atrium-specific positive inotropic effects of quinidine were mimicked by atropine, pirenzepine and dimethylphenylpiperazinium but not by nicotine, cytisine and butyrylcholine; the effects of atropine, dimethylphenylpiperazinium and pirenzepine were also blocked by propranolol. Quinidine increased the release of norepinephrine from atria but not from the ventricles; this release was greater from the right than from the left atria. It is concluded that quinidine- and atropine-like agents exert atrium-specific positive inotropic effects by blocking muscarinic receptors and permitting a dominance of acetylcholine effects via a release of norepinephrine from sympathetic nerve terminals.
- Published
- 1997
20. Pharmacokinetics and protein binding of intravenous ibuprofen in the premature newborn infant
- Author
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Jacob V. Aranda, S Chemtob, Kay D. Beharry, Anastasia Varvarigou, Apostolos Papageorgiou, H Modanlou, C. Bardin, and R Bansal
- Subjects
medicine.medical_specialty ,Ultrafiltration ,Ibuprofen ,Bolus (medicine) ,Pharmacokinetics ,Elimination rate constant ,Internal medicine ,medicine ,Humans ,Cyclooxygenase Inhibitors ,Ductus Arteriosus, Patent ,Chromatography, High Pressure Liquid ,Cerebral Hemorrhage ,Volume of distribution ,Binding Sites ,Maintenance dose ,business.industry ,Age Factors ,Infant, Newborn ,Gestational age ,Electrophoresis, Capillary ,General Medicine ,Blood proteins ,Endocrinology ,Anesthesia ,Pediatrics, Perinatology and Child Health ,business ,Infant, Premature ,medicine.drug ,Protein Binding - Abstract
The elimination, disposition and protein binding of ibuprofen (IBU) in premature infants were studied for use in the prevention of intraventricular hemorrhage and closure of patent ductus arteriosus. The kinetic profile of i.v. IBU lysine (10 mg/kg bolus) given within the first 3 h after birth was studied in 21 premature neonates (mean birthweight = 944.7 g, range: 575-1450 g; gestational age: 26.8 weeks, range: 22-31 weeks). Blood samples (0.3 ml/sample) were obtained at time 0 and at 1, 3, 6, 12, 24, 48, and 72 h post-dose for IBU by high-performance liquid chromatography (HPLC). Kinetic analyses assumed applicability of one open-compartment model and calculations from the model-independent areas under the time concentration curve (AUC). Data (mean +/- SEM) show that apparent volume of distribution (AVd) was 62.1 +/- 3.9 ml/kg, plasma t1/2 beta was 30.5 +/- 4.2 h, elimination rate constant (Kel) was 0.032 +/- 0.004 h-1, plasma clearance was 2.06 +/- 0.33 ml/kg/h and plasma concentration (Cp) at 1 h was 180.6 +/- 11.1 mg/l. Gestational age and birthweight were not related to drug elimination. In 10 neonates, IBU maintenance dose of 5 mg/kg once daily on days 2 and 3 generated mean Cp of 116.6 +/- 54.5 mg/l and 113.6 +/- 58.2 mg/l, respectively. Protein binding by ultrafiltration and capillary electrophoresis showed that the percentage bound IBU was significantly lower in full term cord plasma (94.98 +/- 0.39%, n = 26) compared to adult plasma protein (mean +/- SE = 98.73 +/- 0.31%, n = 8, p0.0001). Compared to data from adults and older children, IBU elimination is markedly prolonged in neonates and protein binding is slightly lower. Thus, investigational and clinical therapeutic regimens should be adjusted to account for decreased drug disposition to ensure safe and effective therapy.
- Published
- 1997
21. SNX30 Negatively Regulates WNT/β-Catenin Signaling by Altering Cell Surface Expression of FZ Receptors
- Author
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Parker B. Antin, Severine Leclerc, S. Chemtob, Gregor Andelfinger, N. Dubois, M. Cameron, and C. Beauséjour
- Subjects
medicine.anatomical_structure ,business.industry ,Cell ,Wnt β catenin signaling ,Medicine ,Surface expression ,Cardiology and Cardiovascular Medicine ,business ,Receptor ,Cell biology - Published
- 2013
22. Ontogenic differences in the functions of myocardial alpha1 adrenoceptor subtypes in rats
- Author
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X F, Deng, S, Chemtob, G, Almazan, and D R, Varma
- Subjects
Rats, Sprague-Dawley ,Norepinephrine ,Phenylephrine ,Dose-Response Relationship, Drug ,Myocardium ,Receptors, Adrenergic, alpha-1 ,Animals ,Heart ,Prazosin ,Methoxamine ,Rats - Abstract
The present study was done to determine possible ontogenic differences in the functions of rat myocardial alpha1, adrenoceptor (alpha1 AR) subtypes in view of reported greater inotropic responses of myocardium of neonatal than of adult rats to alpha1, AR agonists. Methoxamine, phenylephrine and norepinephrine were used as alpha1 AR agonists. Phenylephrine and norepinephrine were used in the presence of 3 microM propranolol. It was found that the ratios of chloroethylclonidine (CEC)-insensitive alpha1 AR subtype (alpha1A AR) to CES-sensitive alpha, AR subtype (alpha1B AR) were approximately 50:50 in neonatal (1 week old) and 20:80 in adult rat ventricles. alpha1A AR selective antagonists WB 4101 and 5-methylurapidil+ (5-MU) inhibited the inotropic effects of alpha1, AR agonists both on neonatal and on adult rat ventricles; in contrast, selective inactivation of alpha1B AR by CEC inhibited the inotropic effects of alpha1 AR agonists only on ventricles from adult but not from neonatal animals. WB 4101 inhibited methoxamine-induced increases in inositol phosphates by ventricular slices from both adult and neonatal rats; in contrast, CEC inhibited these effects of methoxamine only in tissues from adult but not in tissues from neonatal animals. In conclusion, this study, to our knowledge, demonstrates for the first time that the effects of alpha AR agonists on right ventricular contractions and phosphoinositol turnover are mediated primarily by alpha 1A AR subtype in the neonatal and by both alpha1A AR and alpha1B AR subtypes in the adult rat.
- Published
- 1996
23. Early ibuprofen administration to prevent patent ductus arteriosus in premature newborn infants
- Author
-
A, Varvarigou, C L, Bardin, K, Beharry, S, Chemtob, A, Papageorgiou, and J V, Aranda
- Subjects
Male ,Analysis of Variance ,Incidence ,Anti-Inflammatory Agents, Non-Steroidal ,Hemodynamics ,Infant, Newborn ,Ibuprofen ,Infant, Premature, Diseases ,Length of Stay ,Kidney Function Tests ,Echoencephalography ,Respiratory Function Tests ,Survival Rate ,Heart Function Tests ,Prostaglandins ,Humans ,Female ,Prospective Studies ,Infusions, Intravenous ,Ductus Arteriosus, Patent ,Enterocolitis, Pseudomembranous ,Infant, Premature ,Cerebral Hemorrhage - Abstract
To test whether early postnatal (0 to 3 hours) intravenous administration of ibuprofen will prevent patent ductus arteriosus (PDA) in preterm neonates.Prospective sequential controlled trial with three treatment arms.Level 3 perinatal-neonatal intensive care nursery.Thirty-four premature newborn infants born from February to August 1993 with a mean birth weight of 913 g (range, 565 to 1460 g) and gestational age of 26.9 weeks (range, 22.4 to 31.0).Infants were consecutively assigned within 3 hours of age to treatment with either one dose of ibuprofen lysine (10 mg/kg intravenously) followed by 5 mg/kg per dose intravenously at 24 and 48 hours of age (n = 12), one dose of ibuprofen lysine (10 mg/kg intravenously; n = 11), or saline (n = 11).Primary outcome variable was the presence of ductus arteriosus by echocardiography and clinical assessments at 3, 7, and 21 days of life. Secondary outcome variables included presence of intraventricular hemorrhage, renal function, ventilatory and oxygen needs, hematologic changes, gastrointestinal function, time to full enteral feeding, duration of hospitalization, and age at discharge.The three groups of patients were comparable in birth weight, gestational age, antenatal administration of betamethasone, and other perinatal characteristics. Ibuprofen treatment significantly reduced plasma levels of prostaglandins, and the levels remained low for 72 hours in newborns who received three doses of the drug. The incidence of PDA and other variables did not differ between patients who received a single dose of ibuprofen and those given saline. However, compared with the saline-treated newborns, babies who received three doses of ibuprofen had no PDA (0/12 vs 7/11 for saline; P.02), had lower daily mean airway pressures (mean +/- SD, 5.2 +/- 1.1 cm H2O vs 8.3 +/- 2.8 cm H2O for saline; P.02) and better oxygenation index (2.6 +/- 0.6 vs 4.7 +/- 1.8 for saline; P.02) at the end of the first week of life, and required fewer days of ventilation (25 +/- 14 days vs 44 +/- 26 days for saline; P.03). Babies given three doses of ibuprofen tended to tolerate full oral feedings earlier (35 +/- 19 days vs 56 +/- 34 days for saline; P = .09), had shorter duration of hospitalization (71.2 +/- 22.6 days vs 127.3 +/- 74.7 days for saline; P.05), and were discharged to home at an earlier postconceptional age (37.8 +/- 2.0 weeks vs 44.8 +/- 9.8 weeks for saline; P.05). ibuprofen treatment in this phase I trial was not associated with any apparent early neurological, intestinal, renal, hepatic, or hematologic complications.Administration of three doses of ibuprofen within 3 hours after birth in preterm neonates reduced the incidence of PDA without causing notable early adverse drug reactions in this phase I trial. Early closure of the ductus arteriosus was also associated with better respiratory outcome and earlier discharge from the hospital.
- Published
- 1996
24. Up-regulation of brain PGE2 and PGF2 alpha receptors and receptor-coupled second messengers by cyclooxygenase inhibition in newborn pigs
- Author
-
D Y, Li, D R, Varma, and S, Chemtob
- Subjects
Swine ,Indomethacin ,Receptors, Prostaglandin ,Brain ,Ibuprofen ,Inositol 1,4,5-Trisphosphate ,In Vitro Techniques ,Second Messenger Systems ,Up-Regulation ,Animals, Newborn ,16,16-Dimethylprostaglandin E2 ,Prostaglandins F, Synthetic ,Cyclic AMP ,Animals ,Receptors, Prostaglandin E ,Synaptosomes - Abstract
We recently reported that brain synaptosomes of newborn pigs contained fewer PGE2 (EP) and PGF2 alpha (FP) receptors than adult tissues. In the present study we investigated whether this was the result of down-regulation of these receptors by high levels of PGE2 and PGF2 alpha in the brain of newborn animals. Newborn pigs (1-3 days old) were treated with ibuprofen (40 mg/kg) or indomethacin (5 mg/kg) i.v. every 4 hr for 24 hr to reduce prostaglandins to adult levels. At the end of the treatment, EP and FP receptor density and receptor-linked second messenger formation in brain synaptosomes were measured. It was found that ibuprofen and indomethacin treatment increased EP and FP receptor densities in brain synaptosomes of newborn animals to levels found in the adult; this up-regulation of EP receptors was prevented by EP receptor agonist, 16,16-dimethyl-PGE2, and the up-regulation of FP receptors was prevented by the FP agonist, fenprostalene. PGE2, butaprost (an agonist for EP2 receptor subtype mediating cAMP stimulation) and 11-deoxy-PGE1 (an agonist for EP2 and EP3 receptors) caused a comparable increase of cAMP in brain synaptosomes of ibuprofen-treated and adult animals, which was significantly greater than in those of vehicle-treated animals. Also, PGF2 alpha and its analog, fenprostalene, caused a much greater increase in IP3 production in brain synaptosomes of ibuprofen-treated than in vehicle-treated pigs. These findings suggest that the relatively low EP and FP receptor densities in newborn pigs are caused by the high levels of prostaglandins and that these receptors can be up-regulated by inhibiting prostaglandin synthesis.
- Published
- 1995
25. Free radicals in retinal and choroidal blood flow autoregulation in the piglet: interaction with prostaglandins
- Author
-
P, Hardy, D, Abran, D Y, Li, H, Fernandez, D R, Varma, and S, Chemtob
- Subjects
Free Radicals ,Choroid ,Swine ,Anti-Inflammatory Agents, Non-Steroidal ,Retinal Vessels ,Antioxidants ,Peroxides ,Vasodilation ,Prostaglandin-Endoperoxide Synthases ,Regional Blood Flow ,Blood Circulation ,Prostaglandins ,Animals ,Homeostasis ,Ocular Hypertension ,Pregnatrienes - Abstract
To study the role of free radicals in autoregulation of retinal blood flow (RBF) and choroidal blood flow (ChBF) and the contribution of the cyclooxygenase pathway in free radical formation during blood pressure changes in 1- to 3-day-old pigs.Blood pressure was adjusted by inflating balloon-tipped catheters placed at the aortic isthmus and the aortic root to induce hypertension and hypotension, respectively. Blood flow was measured using the microsphere technique. Also, the effects of peroxides on retinal artery diameter were studied on eyecup preparations using time-frame photography processed by digital imaging.Blood gases and intraocular pressure (13 +/- 1 mm Hg) remained stable throughout the experiments. In control animals, RBF was constant only between 30 and 75 mm Hg of ocular perfusion pressure and ChBF increased as a function of ocular perfusion pressure (tau = 0.58, P0.01). Inhibition of peroxidation with the free radical scavenger 21-aminosteroid U74389F (2.5 mg/kg) widened the range of RBF and ChBF autoregulation (ocular perfusion pressure from 30 to 131 mm Hg). Hypertension caused an increase in the products of peroxidation, malondialdehyde, and hydroperoxides, as well as in prostaglandin E2, prostaglandin F2 alpha, and 6-keto-prostaglandin F1 alpha in the retina and choroid of control animals; these changes were inhibited by the free radical scavengers U74389F (2.5 mg/kg) and high-dose allopurinol (140 mg/kg) as well as by the cyclooxygenase inhibitors ibuprofen (40 mg/kg) and indomethacin (5 mg/kg). In isolated eyecup preparations, H2O2 and cumene hydroperoxide dilated retinal vessels, and this effect was completely blocked by indomethacin.These findings indicate that free radicals play a major role in setting the upper limit of RBF and ChBF autoregulation of the newborn animal. In addition, there exists a positive feedback interaction between free radicals and cyclooxygenase activity in ocular tissues, such that during hypertension the cyclooxygenase pathway is an important producer of free radicals and in turn is also activated by them.
- Published
- 1994
26. Deficiency in prostaglandin E2 (PGE2) receptors, mainly EP2 subtype, on brain synaptosomes in early development: implications on cerebral metabolism
- Author
-
S, Chemtob, D Y, Li, and D R, Varma
- Subjects
Animals, Newborn ,Swine ,Cyclic AMP ,Animals ,Brain ,Receptors, Prostaglandin E ,Dinoprostone ,Synaptosomes - Published
- 1994
27. Fewer PGE2 and PGF2 alpha receptors in brain synaptosomes of newborn than of adult pigs
- Author
-
D Y, Li, D R, Varma, T K, Chatterjee, H, Fernandez, D, Abran, and S, Chemtob
- Subjects
Aging ,Swine ,Receptors, Prostaglandin ,Brain ,Inositol 1,4,5-Trisphosphate ,Dinoprost ,Tritium ,Binding, Competitive ,Dinoprostone ,Kinetics ,Animals, Newborn ,Cyclic AMP ,Animals ,Receptors, Prostaglandin E ,Synaptosomes - Abstract
PGE2 and PGF2 alpha decrease cerebral metabolism in the adult but increase it in the newborn. The present study was done using synaptosomes from newborn and adult pigs to find out whether these diverse cerebral effects of prostanoids are a consequence of newborn synaptosomes containing fewer or no EP2 receptors for PGE2 (mediating cAMP increase and in turn cerebral metabolism decrease) and PGF2 alpha receptors [mediating IP3 (inositol 1,4,5-triphosphate) increase and in turn cerebral metabolism decrease]. It was found that maximum binding values (fmol/mg protein) of [3H]PGE2 and [3H]PGF2 alpha were, respectively, only 11.6 +/- 0.8 and 8.6 +/- 1.4 on newborn synaptosomes compared with 41.8 +/- 1.8 and 31.2 +/- 4.8 on adult tissues. EP1 receptors were virtually absent in newborn and adult preparations. Practically all the PGE2 receptors on newborn synaptosomes were EP3 subtype, whereas adult brain synaptosomes contained both EP2 and EP3 subtypes; this was indicated by the ability of MB 28,767, a specific EP3 receptor agonist, to cause 100% displacement of [3H]PGE2 binding to synaptosomes of the newborn but only 51% in the case of the adult. Also, PGE2, 11-deoxy PGE1 (a nonselective EP2 and EP3 agonist) and MB 28,767 (an EP3 agonist) caused comparable decreases in cAMP formation in synaptosomes from the newborn, whereas in those from the adult, PGE2 and 11-deoxy PGE1 increased and MB 28,767 decreased cAMP production. PGF2 alpha markedly increased IP3 synthesis in synaptosomes of the adult but not of the newborn.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1993
28. Endothelium- and beta-2 adrenoceptor-independent relaxation of rat aorta by tyramine and certain other phenylethylamines
- Author
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D R, Varma and S, Chemtob
- Subjects
Male ,Serotonin ,Inositol Phosphates ,Vasodilator Agents ,Tyramine ,Blood Pressure ,In Vitro Techniques ,Nitric Oxide ,Rats ,Rats, Sprague-Dawley ,Norepinephrine ,Pregnancy ,Phenethylamines ,Receptors, Adrenergic, beta ,Cyclic AMP ,Animals ,Humans ,Calcium ,Female ,Endothelium, Vascular ,Enzyme Inhibitors ,Rats, Wistar ,Cyclic GMP ,Aorta - Abstract
At concentrations higher than that required to produce maximal vasoconstriction, tyramine caused concentration-dependent relaxation of rat aortic strips contracted maximally by tyramine, norepinephrine, phenylephrine, 5-hydroxytryptamine, prostaglandin F2 alpha, endothelin, angiotensin II and potassium; isoproterenol did not relax potassium-contracted strips. The vasorelaxant effect of tyramine was not antagonized by propranolol, pindolol or nadolol, all of which markedly antagonized the effects of isoproterenol. The vasorelaxant activity of tyramine was endothelium-independent and not inhibited by hemoglobin, methylene blue or L-NG-nitro arginine; it did not exhibit tachyphylaxis and was neither inhibited by cocaine, guanethidine, reserpine and chemical sympathectomy nor by alpha adrenoceptor, dopamine receptor, 5-hydroxytryptamine receptor, histamine receptor and adenosine receptor antagonists. Inhibition of cyclooxygenase, lipoxygenase and monamine oxidase activities did not decrease the vasorelaxant activity of tyramine. The vasorelaxant effect of tyramine was not decreased by altering external calcium from 0.25 to 4 mM nor was it potentiated by nifedipine. Phenylethylamine was the minimum structural requirement for this propranolol-resistant vasorelaxant activity; beta-carbon and 3-ring hydroxylation abolished this activity, but N-methylation partly overcame the effect of beta-hydroxylation. The vasopressor effect of tyramine in anesthetized rat was reversed to vasodepressor effect by phenoxybenzamine plus propranolol. The propranolol-resistant vasorelaxant effect of tyramine was also confirmed on isolated human placenta arteries. At vasorelaxant concentrations, tyramine did not increase cyclic GMP and cyclic AMP but inhibited inositol-1,4,5-triphosphate. It is suggested that at high concentrations tyramine and related phenylethylamines cause endothelium- and beta-2 adrenoceptor independent vasorelaxation either via specific tyramine receptors or nonselectively.
- Published
- 1993
29. The Evolution of Serum Pge2 During Oral and in travenous Ibuprofen Treatment in Preterm in fants with Patent Ductus Arteriosus (Pda)
- Author
-
M Brassard, A Payot, B Martin, J Miro, Véronique Dorval, and S Chemtob
- Subjects
Patent ductus arteriosus (PDA) ,business.industry ,Anesthesia ,Pediatrics, Perinatology and Child Health ,medicine ,Ibuprofen ,medicine.disease ,business ,medicine.drug - Published
- 2010
30. Dissociation between prostaglandin levels and blood flow to the retina and choroid in the newborn pig after nonsteroidal antiinflammatory drugs
- Author
-
R, Parys-Van Ginderdeuren, D, Malcolm, D R, Varma, J V, Aranda, and S, Chemtob
- Subjects
Naproxen ,Animals, Newborn ,Choroid ,Regional Blood Flow ,Swine ,Anti-Inflammatory Agents, Non-Steroidal ,Indomethacin ,Osmolar Concentration ,Prostaglandins ,Animals ,Retinal Vessels ,Ibuprofen ,Retina - Abstract
To assess whether prostaglandins contribute to the control of basal retinal and choroidal hemodynamics, retinal (RBF) and choroidal blood flow (ChBF) were measured by a microsphere technique in 1- to 4-day-old pigs before and after (at 20 and 60 min) administration of indomethacin (0.3 mg/kg, n = 6 or 10 mg/kg, n = 5), ibuprofen (40 mg/kg, n = 7), naproxen (20 mg/kg, n = 5) or vehicle (n = 8). In 40 other animals, PGF2 alpha, PGE2, and 6-keto-PGF1 alpha were measured in the retina and choroid at times corresponding to blood flow measurements. Mean arterial blood pressure and blood gases and pH were not altered by any of the agents. Except for the lower dose of indomethacin (0.3 mg/kg), which did not change retinal and choroidal prostaglandin concentrations, the prostaglandin levels were decreased similarly (P0.01) by the three drugs. However, RBF and ChBF were not changed by ibuprofen and naproxen, but decreased to the same extent after low and high doses of indomethacin. The data suggest that the effects of indomethacin on RBF and ChBF cannot be simply attributed to prostaglandin synthesis inhibition, and that prostaglandins may not play a significant role in controlling basal blood flow to the retina and choroid.
- Published
- 1992
31. Ibuprofen enhances retinal and choroidal blood flow autoregulation in newborn piglets
- Author
-
S, Chemtob, K, Beharry, J, Rex, T, Chatterjee, D R, Varma, and J V, Aranda
- Subjects
Animals, Newborn ,Choroid ,Regional Blood Flow ,Swine ,Hypertension ,Prostaglandins ,Animals ,Homeostasis ,Retinal Vessels ,Blood Pressure ,Ibuprofen ,Vascular Resistance ,Hypotension - Abstract
The role of prostanoids in setting the range of autoregulation of retinal blood flow (RBF) and choroidal blood flow (ChBF) in the newborn was assessed. The RBF, ChBF, and arterial and cerebral sinus concentrations of PGE, PGF2 alpha, 6-keto-PGF1 alpha and TXB2 were measured over a wide range of mean systemic blood pressure (blood pressure (BP): 17-117 mm Hg) in newborn piglets treated with ibuprofen (30 mg/kg iv) or its vehicle (n = 8, in each group). Hypertension and hypotension were induced 80 min apart on each animal, by inflating balloon-tipped catheters placed at the aortic isthmus and root, respectively. Blood flow and prostanoid concentrations were measured 20 min before (basal) and during the induced changes in BP. In vehicle-treated piglets, RBF did not change with BP between 50 and 90 mm Hg (r = 0.33, P = 0.27), but changed as a function of BP beyond this range (tau = 0.52, P less than 0.01); ChBF increased with BP throughout the range studied (17-117 mm Hg; tau = 0.89, P less than 0.001). The relationship between O2 delivery to the retina and choroid and BP (tau greater than 0.43, P less than 0.01) was similar to that seen between RBF and ChBF with BP. The concentration of all prostanoids increased when BP was reduced to less than 50 mm Hg. When BP was raised to more than 90 mm Hg, prostaglandin concentrations increased, and those of TXB2 did not change. Ibuprofen treatment reduced the basal concentrations of all prostanoids to nearly undetectable levels and prevented their changes during hypotension and hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1991
32. Changes in cerebrovascular prostaglandins and thromboxane as a function of systemic blood pressure. Cerebral blood flow autoregulation of the newborn
- Author
-
S. Chemtob, Jacob V. Aranda, J Rex, K Beharry, and D R Varma
- Subjects
medicine.medical_specialty ,Physiology ,Thromboxane ,Swine ,Hemodynamics ,Blood Pressure ,6-Ketoprostaglandin F1 alpha ,Dinoprost ,Internal medicine ,medicine ,Animals ,Homeostasis ,Chemistry ,Prostaglandins E ,Thromboxanes ,Blood flow ,Thromboxane B2 ,Endocrinology ,medicine.anatomical_structure ,Blood pressure ,Cerebral blood flow ,Animals, Newborn ,Anesthesia ,Cerebrovascular Circulation ,Circulatory system ,cardiovascular system ,Prostaglandins ,lipids (amino acids, peptides, and proteins) ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,Vasoconstriction ,circulatory and respiratory physiology ,Blood vessel - Abstract
Cerebrovascular concentrations of prostaglandin E (PGE), prostaglandin F2 alpha (PGF2 alpha), 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), and thromboxane B2 (TXB2) were determined over a blood pressure range of 17-117 mm Hg (induced by inflation of balloon-tipped catheters placed in the thoracic descending aorta and at the aortic root) in eight newborn piglets to access the role of prostanoids in cerebral blood flow (CBF; measured using radioactive microspheres) autoregulation. Basal systemic blood pressure, heart rate, blood gases, total CBF, and prostanoid concentrations were stable. CBF was constant between 50 and 90 mm Hg, but beyond this range CBF varied directly with blood pressure (tau = 0.48; p less than 0.05). Sagittal sinus concentrations of PGE, PGF2 alpha, and 6-keto-PGF1 alpha varied with blood pressure according to a quadratic function (R2 = 0.92 to 0.96; p less than 0.0001), exhibiting lowest values between mean blood pressures of 60 and 90 mm Hg. During hypotension (17-49 mm Hg), there was a greater relative increase in sagittal sinus concentrations of TXB2 than of PGE, PGF2 alpha, and 6-keto-PGF1 alpha; at the lowest blood pressures, TXB2 increased by 658 +/- 44%, and prostaglandins increased on the average by 331 +/- 49% (p less than 0.01) from their values during normotension (50-90 mm Hg). During hypertension (91-117 mm Hg), cerebrovascular production and concentrations of prostaglandins increased by 142 +/- 31% and 45 +/- 10%, respectively, but did not change for TXB2.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1990
33. Isoprostanes Induce Retinal Vasoobliteration, a Key Feature of Retinopathy of Prematurity (ROP)
- Author
-
S. Chemtob, Pierre Lachapelle, Marilise Marrache, K. G Peri, Guillermina Almazan, Katherine Martinez-Bermudez, Olga Dembinska, Daya R Varma, and Xin Hou
- Subjects
congenital, hereditary, and neonatal diseases and abnormalities ,medicine.medical_specialty ,genetic structures ,business.industry ,Retinopathy of prematurity ,Retinal ,medicine.disease ,Isoprostanes ,eye diseases ,chemistry.chemical_compound ,chemistry ,Feature (computer vision) ,Ophthalmology ,Pediatrics, Perinatology and Child Health ,medicine ,Key (cryptography) ,sense organs ,business - Abstract
Isoprostanes Induce Retinal Vasoobliteration, a Key Feature of Retinopathy of Prematurity (ROP)
- Published
- 1999
34. Crosstalk between alpha-1A and alpha-1B adrenoceptors in neonatal rat myocardium: implications in cardiac hypertrophy.
- Author
-
F, Deng X, A, Sculptoreanu, S, Mulay, G, Peri K, F, Li J, H, Zheng W, S, Chemtob, and R, Varma D
- Abstract
The myocardial effect of alpha-1A adrenoceptor (alpha-1 AR) agonists in neonatal rats are mediated by alpha-1A AR and not by alpha-1B AR, although both receptor subtypes are equally expressed; the functions of alpha-1B AR are not known. Here, we report that alpha-1 B ARs inhibit the activities of alpha-1A ARs in neonatal rat myocardium so that the inactivation of alpha-1 B ARs by chloroethylclonidine (CEC) potentiated the effects of nonselective alpha-1 AR agonist phenylephrine (PE) on myocardial protein synthesis and early gene (c-fos and c-jun) expression. CEC did not modify the hypertrophic effect of angiotensin II. The potentiation of the effects of PE by CEC was associated with a translocation of Ca(++)-dependent protein kinase C (PKC)alpha, which did not occur in the absence of CEC. Alpha-1A AR-selective agonist A61603 was approximately 1000-fold more potent than PE as a positive inotropic agent; it caused the translocation of PKC alpha, which was not affected by CEC. 5-Methylurapidil antagonized the effects of PE and A61603, suggesting that these were mediated via alpha-1A ARs. Alpha-1D AR antagonist BMY 7378 did not modify PE-induced translocation of PKC. CEC potentiated the effects of PE on Ca++ transients in Fura 2-AM-loaded dispersed cardiomyocytes, and this potentiation was prevented by nifedipine. In whole-cell patch-clamp recordings of cultured cardiomyocytes, CEC potentiated the effect of norepinephrine on Ca++ channel currents, which was blocked by 5-methylurapidil. We conclude that alpha-1A ARs are positively and alpha-1B ARs are negatively coupled to nifedipine-sensitive Ca++ channels, possibly via Gi protein, and this antagonistic relationship between alpha-A AR and alpha-1B AR in the neonatal heart might be required physiologically for normal alpha-1 AR-mediated responses and myocardial development.
- Published
- 1998
35. Mechanisms of the atrium-specific positive inotropic activities of quinidine- and atropine-like agents in rats.
- Author
-
F, Deng X, S, Mulay, S, Chemtob, and R, Varma D
- Abstract
This study investigated the mechanism of the positive inotropic effects of class 1 antiarrhythmic agents using electrically stimulated right atria (sinoatrial node excised), left atria and right ventricles of rats. Quinidine, disopyramide and procainamide produced concentration-dependent positive inotropic effects on right and left atria; effects on the right atria were greater than on left atria. At concentration producing positive inotropic effects on atria, the contractions of right ventricles were slightly increased by quinidine, unaffected by disopyramide and decreased by procainamide. The positive inotropic effects of quinidine were inhibited by propranolol, reserpine and mecamylamine but not by cocaine, hexamethonium and d-tubocurarine; propranolol also antagonized the positive inotropic effects of disopyramide and procainamide. Bupivacaine, which like quinidine blocks transient outward potassium current, slightly increased the contractions of right atria but not of left atria and ventricles. The atrium-specific positive inotropic effects of quinidine were mimicked by atropine, pirenzepine and dimethylphenylpiperazinium but not by nicotine, cytisine and butyrylcholine; the effects of atropine, dimethylphenylpiperazinium and pirenzepine were also blocked by propranolol. Quinidine increased the release of norepinephrine from atria but not from the ventricles; this release was greater from the right than from the left atria. It is concluded that quinidine- and atropine-like agents exert atrium-specific positive inotropic effects by blocking muscarinic receptors and permitting a dominance of acetylcholine effects via a release of norepinephrine from sympathetic nerve terminals.
- Published
- 1997
36. Furosemide and vitamin E. Two problem drugs in neonatology
- Author
-
J V, Aranda, S, Chemtob, N, Laudignon, and B I, Sasyniuk
- Subjects
Heart Failure ,Respiratory Distress Syndrome, Newborn ,Infant, Newborn ,Water-Electrolyte Imbalance ,Anemia ,Pulmonary Edema ,Infant, Premature, Diseases ,Acid-Base Imbalance ,Infant, Newborn, Diseases ,Diuresis ,Kidney Tubules ,Retinal Diseases ,Furosemide ,Humans ,Vitamin E ,Ductus Arteriosus, Patent ,Bronchopulmonary Dysplasia ,Cerebral Hemorrhage ,Glomerular Filtration Rate - Abstract
This article focuses on some of the problems encountered with two of the drugs currently given to newborns.
- Published
- 1986
37. Syndrome of Inappropriate Secretion of Antidiuretic Hormone in Enteroviral Meningitis
- Author
-
Elena R. Reece, Elaine L. Mills, and S. Chemtob
- Subjects
Pediatrics ,medicine.medical_specialty ,Vasopressin ,business.industry ,Infant ,Aseptic meningitis ,medicine.disease ,medicine.disease_cause ,Meningitis, Viral ,Inappropriate ADH Syndrome ,El Niño ,Child, Preschool ,Pediatrics, Perinatology and Child Health ,Immunology ,Enterovirus Infections ,medicine ,Humans ,Enterovirus ,Viral disease ,Child ,business ,Meningitis ,Antidiuretic ,Hormone - Abstract
• In nine of 102 children admitted to the Montreal Children's Hospital with a diagnosis of aseptic meningitis, the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) developed. Patients with and without SIADH were similar with respect to clinical symptoms, duration of illness, and CSF inflammatory response. The SIADH group differed in that the largest age group was 1 to 5 years. ( AJDC 1985;139:292-294)
- Published
- 1985
38. 1364 PROTECIIVE ROLE OF BETAMETHASONE(B) ON RLF IN NEWBOENS WITH BIRTH WEIGHT OF <1000GMS
- Author
-
S Chemtob, Apostolos Papageorgiou, and Ildiko Kunos
- Subjects
Pediatrics ,medicine.medical_specialty ,business.industry ,Incidence (epidemiology) ,Birth weight ,medicine.disease ,Low birth weight ,Intraventricular hemorrhage ,Relative risk ,Statistical significance ,Pediatrics, Perinatology and Child Health ,medicine ,Betamethasone ,medicine.symptom ,Complication ,business ,medicine.drug - Abstract
Antenatal B has been shown to decrease the incidence and severity of RDS. Among low birth weight infants RLF remains the most common serious complication after intraventricular hemorrhage. Steroids have been used postnatally in an attempt to treat RLF, without success. However, the possible protective role of steroids has not been evaluated. In view of the extensive use of B in our center, we have assessed by multivariant analysis its effect on RLF. Among 204 infants in the 1000-1500gms category, no statistically significant difference was found between those who received B and those who did not. However, among the 51 infants weighing
- Published
- 1985
39. Mast cells promote choroidal neovascularization in a model of age-related macular degeneration.
- Author
-
Dabouz R, Abram P, Rivera JC, and Chemtob S
- Subjects
- Animals, Mice, Endothelial Cells metabolism, Endothelial Cells pathology, Choroid pathology, Choroid metabolism, Tryptases metabolism, Mice, Transgenic, Ketotifen pharmacology, Mast Cells metabolism, Mast Cells pathology, Choroidal Neovascularization metabolism, Choroidal Neovascularization pathology, Disease Models, Animal, Mice, Inbred C57BL, Macular Degeneration pathology, Macular Degeneration metabolism
- Abstract
'Wet' age-related macular degeneration (AMD) is characterized by pathologic choroidal neovascularization (CNV) that destroys central vision. Abundant evidence points to inflammation and immune cell dysfunction in the progression of CNV in AMD. Mast cells are resident immune cells that control the inflammatory response. Mast cells accumulate and degranulate in the choroid of patients with AMD, suggesting they play a role in CNV. Activated mast cells secrete various biologically active mediators, including inflammatory cytokines and proteolytic enzymes such as tryptase. We investigated the role of mast cells in AMD using a model of CNV. Conditioned media from activated mast cells exerts proangiogenic effects on choroidal endothelial cells and choroidal explants. Laser-induced CNV in vivo was markedly attenuated in mice genetically depleted of mast cells (Kit
W-sh/W-sh ) and in wild-type mice treated with mast cell stabilizer, ketotifen fumarate. Tryptase was found to elicit pronounced choroidal endothelial cell sprouting, migration and tubulogenesis; while tryptase inhibition diminished CNV. Transcriptomic analysis of laser-treated RPE/choroid complex revealed collagen catabolism and extracellular matrix (ECM) reorganization as significant events correlated in clusters of mast cell activation. Consistent with these analyses, compared to wildtype mice choroids of laser-treated mast cell-deficient mice displayed less ECM remodelling evaluated using collagen hybridizing peptide tissue binding. Findings herein provide strong support for mast cells as key players in the progression of pathologic choroidal angiogenesis and as potential therapeutic targets to prevent pathological neovascularization in 'wet' AMD., (© 2024. The Author(s).)- Published
- 2024
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40. Endoplasmic Reticulum Stress Delays Choroid Development in the HCAR1 Knockout Mouse.
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Modaresinejad M, Yang X, Mohammad Nezhady MA, Zhu T, Bajon E, Hou X, Tahiri H, Hardy P, Rivera JC, Lachapelle P, and Chemtob S
- Abstract
The subretina, composed of the choroid and the retinal pigment epithelium (RPE), bears a critical role in proper vision. In addition to phagocytosis of photoreceptor debris, the RPE shuttles oxygen and nutrients to the neuroretina. For their own energy production, RPE cells mainly rely on lactate, a major by-product of glycolysis. Lactate, in turn, is believed to convey most of its biological effects via the hydroxycarboxylic acid receptor 1 (HCAR1). Here, the lactate-specific receptor, HCAR1, is found to be exclusively expressed in the RPE cells within the subretina, and Hcar1
-/- mice exhibit a substantially thinner choroidal vasculature during development. Notably, the angiogenic properties of lactate on the choroid are impacted by the absence of Hcar1. HCAR1-deficient mice exhibit elevated endoplasmic reticulum stress along with eukaryotic initiation factor 2α phosphorylation, a significant decrease in the global protein translation rate, and a lower proliferation rate of choroidal vasculature. Strikingly, inhibition of the integrated stress response using an inhibitor that reverses the effect of eukaryotic initiation factor 2α phosphorylation restores protein translation and rescues choroidal thinning. These results provide evidence that lactate signalling via HCAR1 is important for choroidal development/angiogenesis and highlight the importance of this receptor in establishing mature vision., Competing Interests: Disclosure Statement None declared., (Copyright © 2024 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)- Published
- 2024
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41. Inflammatory mechanisms of preterm labor and emerging anti-inflammatory interventions.
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Habelrih T, Augustin TL, Mauffette-Whyte F, Ferri B, Sawaya K, Côté F, Gallant M, Olson DM, and Chemtob S
- Subjects
- Humans, Pregnancy, Female, Premature Birth immunology, Premature Birth prevention & control, Animals, Infant, Newborn, Obstetric Labor, Premature immunology, Inflammation immunology, Anti-Inflammatory Agents therapeutic use
- Abstract
Preterm birth is a major public health concern, requiring a deeper understanding of its underlying inflammatory mechanisms and to develop effective therapeutic strategies. This review explores the complex interaction between inflammation and preterm labor, highlighting the pivotal role of the dysregulation of inflammation in triggering premature delivery. The immunological environment of pregnancy, characterized by a fragile balance of immune tolerance and resistance, is disrupted in preterm labor, leading to a pathological inflammatory response. Feto-maternal infections, among other pro-inflammatory stimuli, trigger the activation of toll-like receptors and the production of pro-inflammatory mediators, promoting uterine contractility and cervical ripening. Emerging anti-inflammatory therapeutics offer promising approaches for the prevention of preterm birth by targeting key inflammatory pathways. From TLR-4 antagonists to chemokine and interleukin receptor antagonists, these interventions aim to modulate the inflammatory environment and prevent adverse pregnancy outcomes. In conclusion, a comprehensive understanding of the inflammatory mechanisms leading to preterm labor is crucial for the development of targeted interventions in hope of reducing the incidence of preterm birth and improving neonatal health outcomes., Competing Interests: Declaration of Competing Interest S.C. holds a patent on composition of matter for the use of 101.10/rytvela (IL-1 receptor antagonists, compositions, and methods of treatment, United States patent no. USPTO8618054, May 5, 2005). S.C. and D.M.O. hold a patent on methods for reducing perinatal morbidity and/or mortality (US20210322509, March 9, 2016). The remaining authors have no financial conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2024
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42. Selective Enrichment of Angiomirs in Extracellular Vesicles Released from Ischemic Skeletal Muscles: Potential Role in Angiogenesis and Neovascularization.
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Dussault S, Desjarlais M, Raguema N, Boilard E, Chemtob S, and Rivard A
- Subjects
- Animals, Mice, Hindlimb blood supply, Hindlimb pathology, Mice, Inbred C57BL, Signal Transduction, Male, Exosomes metabolism, Neovascularization, Pathologic metabolism, Angiogenesis, Muscle, Skeletal metabolism, Muscle, Skeletal blood supply, Muscle, Skeletal pathology, Extracellular Vesicles metabolism, MicroRNAs metabolism, MicroRNAs genetics, Ischemia metabolism, Ischemia pathology, Neovascularization, Physiologic
- Abstract
MicroRNAs (miRs) regulate physiological and pathological processes, including ischemia-induced angiogenesis and neovascularization. They can be transferred between cells by extracellular vesicles (EVs). However, the specific miRs that are packaged in EVs released from skeletal muscles, and how this process is modulated by ischemia, remain to be determined. We used a mouse model of hindlimb ischemia and next generation sequencing (NGS) to perform a complete profiling of miR expression and determine the effect of ischemia in skeletal muscles, and in EVs of different sizes (microvesicles (MVs) and exosomes) released from these muscles. Ischemia significantly modulated miR expression in whole muscles and EVs, increasing the levels of several miRs that can have pro-angiogenic effects (angiomiRs). We found that specific angiomiRs are selectively enriched in MVs and/or exosomes in response to ischemia. In silico approaches indicate that these miRs modulate pathways that play key roles in angiogenesis and neovascularization, including HIF1/VEGF signaling, regulation of actin cytoskeleton and focal adhesion, NOTCH, PI3K/AKT, RAS/MAPK, JAK/STAT, TGFb/SMAD signaling and the NO/cGMP/PKG pathway. Thus, we show for the first time that angiomiRs are selectively enriched in MVs and exosomes released from ischemic muscles. These angiomiRs could be targeted in order to improve the angiogenic function of EVs for potential novel therapeutic applications in patients with severe ischemic vascular diseases.
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- 2024
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43. Preventing Preterm Birth: Exploring Innovative Solutions.
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Habelrih T, Ferri B, Côté F, Sévigny J, Augustin TL, Sawaya K, Lubell WD, Olson DM, Girard S, and Chemtob S
- Subjects
- Humans, Pregnancy, Female, Infant, Newborn, Inflammation drug therapy, Inflammation prevention & control, Obstetric Labor, Premature prevention & control, Premature Birth prevention & control, Tocolytic Agents therapeutic use
- Abstract
This review examines the complexities of preterm birth (PTB), emphasizes the pivotal role of inflammation in the pathogenesis of preterm labor, and assesses current available interventions. Antibiotics, progesterone analogs, mechanical approaches, nonsteroidal anti-inflammatory drugs, and nutritional supplementation demonstrate a limited efficacy. Tocolytic agents, targeting uterine activity and contractility, inadequately prevent PTB by neglecting to act on uteroplacental inflammation. Emerging therapies targeting toll-like receptors, chemokines, and interleukin receptors exhibit promise in mitigating inflammation and preventing PTB., Competing Interests: Disclosure S. Chemtob and W.D. Lubell hold a patent on composition of matter for the use of 101.10/rytvela (IL-1 receptor antagonists, compositions, and methods of treatment, United States patent no. USPTO8618054, May 5, 2005). S Chemtob, WD Lubell, DM Olson, and S Girard hold a patent on methods for reducing perinatal morbidity and/or mortality (US20210322509, March 9, 2016)., (Copyright © 2024 Elsevier Inc. All rights reserved.)
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- 2024
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44. Versatile lactate signaling via HCAR1: a multifaceted GPCR involved in many biological processes.
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Mohammad Nezhady MA, Modaresinejad M, Zia A, and Chemtob S
- Subjects
- Signal Transduction, Receptors, G-Protein-Coupled metabolism, Cell Membrane metabolism, Lactic Acid metabolism, Biological Phenomena
- Abstract
G-coupled protein receptors (GPCRs) are the ultimate refuge of pharmacology and medicine as more than 40% of all marketed drugs are directly targeting these receptors. Through cell surface expression, they are at the forefront of cellular communication with the outside world. Metabolites among the conveyors of this communication are becoming more prominent with the recognition of them as ligands for GPCRs. HCAR1 is a GPCR conveyor of lactate. It is a class A GPCR coupled to G
αi which reduces cellular cAMP along with the downstream Gβγ signaling. It was first found to inhibit lipolysis, and lately has been implicated in diverse cellular processes, including neural activities, angiogenesis, inflammation, vision, cardiovascular function, stem cell proliferation, and involved in promoting pathogenesis for different conditions, such as cancer. Other than signaling from the plasma membrane, HCAR1 shows nuclear localization with different location-biased activities therein. Although different functions for HCAR1 are being discovered, its cell and molecular mechanisms are yet ill understood. Here, we provide a comprehensive review on HCAR1, which covers the literature on the subject, and discusses its importance and relevance in various biological phenomena.- Published
- 2023
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45. Disentangling the nonmetabolic roles of metabolites: lactate as a case study.
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Mohammad Nezhady MA, Bajon E, and Chemtob S
- Subjects
- Humans, Protein Processing, Post-Translational, Lactic Acid, Signal Transduction
- Abstract
Many metabolites possess covalent and noncovalent signaling functions. However, ongoing research considers them mostly as ligands, neglecting their potential involvement in post-translational modifications. In this forum article, we discuss the dual signaling functions of metabolites, using lactate as a case study, and advocate for the use of multiple complementary techniques to disentangle their functions., Competing Interests: Declaration of interests No interests are declared., (Copyright © 2023 Elsevier Ltd. All rights reserved.)
- Published
- 2023
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46. Lack of HCAR1, the lactate GPCR, signaling promotes autistic-like behavior.
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Mohammad Nezhady MA, Cagnone G, Joyal JS, and Chemtob S
- Subjects
- Mice, Animals, Lactic Acid metabolism, Signal Transduction, Receptors, G-Protein-Coupled metabolism, Autistic Disorder, Autism Spectrum Disorder
- Abstract
The GPCR HCAR1 is known to be the sole receptor for lactate, which modulates its metabolic effects. Despite its significant role in many processes, mice deficient in HCAR1 exhibit no visible phenotype and are healthy and fertile. We performed transcriptomic analysis on HCAR1 deficient cells, in combination with lactate, to explore pathophysiologically altered processes. Processes such as immune regulation, various cancers, and neurodegenerative diseases were significantly enriched for HCAR1 transcriptomic signature. However, the most affected process of all was autism spectrum disorder. We performed behavioral tests on HCAR1 KO mice and observed that these mice manifest autistic-like behavior. Our data opens new avenues for research on HCAR1 and lactate effect at a pathological level. Video Abstract., (© 2023. BioMed Central Ltd., part of Springer Nature.)
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- 2023
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47. Pharmacological blockade of the interleukin-1 receptor suppressed Escherichia coli lipopolysaccharide-induced neuroinflammation in preterm fetal sheep.
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Takahashi Y, Takahashi T, Usuda H, Carter S, Fee EL, Furfaro L, Chemtob S, Olson DM, Keelan JA, Kallapur S, and Kemp MW
- Subjects
- Animals, Female, Pregnancy, Amniotic Fluid chemistry, Amniotic Fluid metabolism, Escherichia coli, Interleukin 1 Receptor Antagonist Protein pharmacology, Interleukin 1 Receptor Antagonist Protein analysis, Interleukin-1 analysis, Lipopolysaccharides analysis, Receptors, Interleukin-1 analysis, Sheep, Disease Models, Animal, Animals, Newborn, Anti-Inflammatory Agents administration & dosage, Anti-Inflammatory Agents analysis, Chorioamnionitis chemically induced, Chorioamnionitis drug therapy, Chorioamnionitis immunology, Neuroinflammatory Diseases immunology, Neuroinflammatory Diseases prevention & control, Premature Birth immunology, Premature Birth prevention & control
- Abstract
Background: Intraamniotic inflammation is associated with preterm birth, especially in cases occurring before 32 weeks' gestation, and is causally linked with an increased risk for neonatal mortality and morbidity. Targeted anti-inflammatory interventions may assist in improving the outcomes for pregnancies impacted by intrauterine inflammation. Interleukin-1 is a central upstream mediator of inflammation. Accordingly, interleukin-1 is a promising candidate target for intervention therapies and has been targeted previously using the interleukin-1 receptor antagonist, anakinra. Recent studies have shown that the novel, noncompetitive, allosteric interleukin-1 receptor inhibitor, rytvela, partially resolved inflammation associated with preterm birth and fetal injury. In this study, we used a preterm sheep model of chorioamnionitis to investigate the anti-inflammatory efficacy of rytvela and anakinra, administered in the amniotic fluid in the setting of intraamniotic Escherichia coli lipopolysaccharide exposure., Objective: We hypothesized that both rytvela and anakinra would reduce lipopolysaccharide-induced intrauterine inflammation and protect the fetal brain., Study Design: Ewes with a singleton fetus at 105 days of gestation (term is ∼150 days) were randomized to one of the following groups: (1) intraamniotic injections of 2 mL saline at time=0 and time=24 hours as a negative control group (saline group, n=12); (2) intraamniotic injection of 10 mg Escherichia coli lipopolysaccharide in 2 mL saline and intraamniotic injections of 2 mL saline at time=0 hours and time=24 hours as an inflammation positive control group (lipopolysaccharide group, n=11); (3) intraamniotic injection of Escherichia coli lipopolysaccharide in 2 mL saline and intraamniotic injections of 2.5 mg rytvela at time=0 hours and time=24 hours to test the anti-inflammatory efficacy of rytvela (lipopolysaccharide + rytvela group, n=10); or (4) intraamniotic injection of Escherichia coli lipopolysaccharide in 2 mL saline and intraamniotic injections of 100 mg anakinra at time=0 hours and time=24 hours to test the anti-inflammatory efficacy of anakinra (lipopolysaccharide + anakinra group, n=12). Amniotic fluid was sampled at time 0, 24, and 48 hours (ie, at each intervention and at delivery). Fetal umbilical cord blood was collected at delivery for differential blood counts and chemical studies. Inflammation was characterized by the analysis of fetal tissue cytokine and chemokine levels using quantitative polymerase chain reaction, enzyme-linked inmmunosorbent assay, and histology. The primary study outcome of interest was the assessment of anakinra and rytvela brain-protective effects in the setting of Escherichia coli lipopolysaccharide-induced intrauterine inflammation. Secondary outcomes of interest were to assess protection from fetal and intrauterine (ie, amniotic fluid, chorioamnion) inflammation., Results: Intraamniotic administration of lipopolysaccharide caused inflammation of the fetal lung, brain, and chorioamnionitis in preterm fetal sheep. Relative to treatment with saline only in the setting of lipopolysaccharide exposure, intraamniotic administration of both rytvela and anakinra both significantly prevented periventricular white matter injury, microglial activation, and histologic chorioamnionitis. Anakinra showed additional efficacy in inhibiting fetal lung myeloperoxidase activity, but its use was associated with metabolic acidaemia and reduced fetal plasma insulin-like growth factor-1 levels at delivery., Conclusion: Intraamniotic administration of rytvela or anakinra significantly inhibited fetal brain inflammation and chorioamnionitis in preterm fetal sheep exposed to intraamniotic lipopolysaccharide. In addition, anakinra treatment was associated with potential negative impacts on the developing fetus., (Copyright © 2023. Published by Elsevier Inc.)
- Published
- 2023
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48. A systematic review of immune-based interventions for perinatal neuroprotection: closing the gap between animal studies and human trials.
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Kelly SB, Tran NT, Polglase GR, Hunt RW, Nold MF, Nold-Petry CA, Olson DM, Chemtob S, Lodygensky GA, Robertson SA, Gunn AJ, and Galinsky R
- Subjects
- Pregnancy, Animals, Female, Humans, Brain, Neuroprotection, Anti-Inflammatory Agents
- Abstract
Background: Perinatal infection/inflammation is associated with a high risk for neurological injury and neurodevelopmental impairment after birth. Despite a growing preclinical evidence base, anti-inflammatory interventions have not been established in clinical practice, partly because of the range of potential targets. We therefore systematically reviewed preclinical studies of immunomodulation to improve neurological outcomes in the perinatal brain and assessed their therapeutic potential., Methods: We reviewed relevant studies published from January 2012 to July 2023 using PubMed, Medline (OvidSP) and EMBASE databases. Studies were assessed for risk of bias using the SYRCLE risk of bias assessment tool (PROSPERO; registration number CRD42023395690)., Results: Forty preclinical publications using 12 models of perinatal neuroinflammation were identified and divided into 59 individual studies. Twenty-seven anti-inflammatory agents in 19 categories were investigated. Forty-five (76%) of 59 studies reported neuroprotection, from all 19 categories of therapeutics. Notably, 10/10 (100%) studies investigating anti-interleukin (IL)-1 therapies reported improved outcome, whereas half of the studies using corticosteroids (5/10; 50%) reported no improvement or worse outcomes with treatment. Most studies (49/59, 83%) did not control core body temperature (a known potential confounder), and 25 of 59 studies (42%) did not report the sex of subjects. Many studies did not clearly state whether they controlled for potential study bias., Conclusion: Anti-inflammatory therapies are promising candidates for treatment or even prevention of perinatal brain injury. Our analysis highlights key knowledge gaps and opportunities to improve preclinical study design that must be addressed to support clinical translation., (© 2023. BioMed Central Ltd., part of Springer Nature.)
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- 2023
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49. Novel Function of Nogo-A as Negative Regulator of Endothelial Progenitor Cell Angiogenic Activity: Impact in Oxygen-Induced Retinopathy.
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Ruknudin P, Nazari AR, Wirth M, Lahaie I, Bajon E, Rivard A, Chemtob S, and Desjarlais M
- Subjects
- Animals, Rats, Oxygen adverse effects, Nogo Proteins genetics, Hyperoxia complications, Endothelial Progenitor Cells, Retinal Diseases
- Abstract
Endothelial Progenitor Cells (EPCs) can actively participate in revascularization in oxygen-induced retinopathy (OIR). Yet the mechanisms responsible for their dysfunction is unclear. Nogo-A, whose function is traditionally related to the inhibition of neurite function in the central nervous system, has recently been documented to display anti-angiogenic pro-repellent properties. Based on the significant impact of EPCs in retinal vascularization, we surmised that Nogo-A affects EPC function, and proceeded to investigate the role of Nogo-A on EPC function in OIR. The expression of Nogo-A and its specific receptor NgR1 was significantly increased in isolated EPCs exposed to hyperoxia, as well as in EPCs isolated from rats subjected to OIR compared with respective controls (EPCs exposed to normoxia). EPCs exposed to hyperoxia displayed reduced migratory and tubulogenic activity, associated with the suppressed expression of prominent EPC-recruitment factors SDF-1/CXCR4. The inhibition of Nogo-A (using a Nogo-66 neutralizing antagonist peptide) or siRNA-NGR1 in hyperoxia-exposed EPCs restored SDF-1/CXCR4 expression and, in turn, rescued the curtailed neovascular functions of EPCs in hyperoxia. The in vivo intraperitoneal injection of engineered EPCs (Nogo-A-inhibited or NgR1-suppressed) in OIR rats at P5 (prior to exposure to hyperoxia) prevented retinal and choroidal vaso-obliteration upon localization adjacent to vasculature; coherently, the inhibition of Nogo-A/NgR1 in EPCs enhanced the expression of key angiogenic factors VEGF, SDF-1, PDGF, and EPO in retina; CXCR4 knock-down abrogated suppressed NgR1 pro-angiogenic effects. The findings revealed that hyperoxia-induced EPC malfunction is mediated to a significant extent by Nogo-A/NgR1 signaling via CXCR4 suppression; the inhibition of Nogo-A in EPCs restores specific angiogenic growth factors in retina and the ensuing vascularization of the retina in an OIR model.
- Published
- 2023
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50. Pharmacodynamic characterization of rytvela, a novel allosteric anti-inflammatory therapeutic, to prevent preterm birth and improve fetal and neonatal outcomes.
- Author
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Habelrih T, Tremblay DÉ, Di Battista E, Hou X, Reuben A, Ferri B, Loiselle SE, Côté F, Abram P, Lubell WD, Leimert KB, Quiniou C, Girard S, Olson DM, and Chemtob S
- Subjects
- Infant, Newborn, Pregnancy, Humans, Female, Animals, Mice, Lipopolysaccharides adverse effects, Fetus, Inflammation, Anti-Inflammatory Agents, Interleukin-1, Premature Birth prevention & control
- Abstract
Background: Preterm birth is the leading cause of neonatal morbidity and mortality. Studies have shown that interleukin 1 plays a major role in the pathophysiology of preterm birth by inducing the production of proinflammatory mediators and uterine activation proteins leading to labor. More importantly, uteroplacental inflammation, associated with preterm birth parturition pathways, is detrimental to fetal tissues and leads to long-term sequelae. Our group has developed an allosteric antagonist of the interleukin 1 receptor, rytvela, found to be potent and safe in preventing preterm birth by suppressing inflammation via the inhibition of the mitogen-activated protein kinase pathway while preserving the Nuclear factor kappa B pathway (important in immune vigilance). Rytvela has been shown to inhibit inflammatory up-regulation and uterine activation while preserving fetal development., Objective: This study aimed to further the preclinical development of rytvela by evaluating its optimal dose and minimal duration of treatment to inhibit the inflammatory cascade, prolong gestation, and promote neonatal outcomes., Study Design: Pregnant CD-1 mice were administered with lipopolysaccharide (10 μg, intraperitoneal administration) or interleukin 1 (1 μg/kg, intrauterine administration) on gestational day 16 to induce preterm labor. Rytvela was administered at different doses (0.1, 0.5, 1.0, 2.0, 4.0 mg/kg/d subcutaneously) from gestational days 16 to 18.5. To evaluate the minimal duration of treatment, the mice were administered with rytvela (2 mg/kg/d subcutaneously) for 24, 36, or 48 hours. The rate of prematurity (gestational day <18.5) and neonate survival and weight were evaluated. Gestational tissues were collected at gestational day 17.5 to quantify cytokines, proinflammatory mediators, and uterine activating proteins by real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. The neonatal lungs and intestines were collected from postnatal days 5 to 7 and analyzed by histology., Results: Rytvela exhibited a dose-response profile and achieved maximum efficacy at a dose of 2 mg/kg/d by reducing 70% of lipopolysaccharide-induced preterm births and 60% of interleukin 1β-induced preterm births. In addition, rytvela attained maximum efficacy at a dose of 1 mg/kg/d by increasing neonate survival by up to 65% in both models of preterm birth. Rytvela protected fetuses from inflammatory insult as of 24 hours, preserving lung and intestinal integrity, and prevented preterm birth and fetal mortality by 60% and 50%, respectively, as of 36 hours of treatment., Conclusion: The maximum efficacy of rytvela was achieved at 2 mg/kg/d with improved birth outcomes and prevented inflammatory up-regulation upon 36 hours (only) of treatment. Rytvela exhibited desirable properties for the safe prevention of preterm birth and fetal protection., (Copyright © 2022 Elsevier Inc. All rights reserved.)
- Published
- 2023
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