bluuebunny/crossref_metadata_2025 huggingface dataset:
Beneficial effects of MET‐88 on left ventricular dysfunction and hypertrophy with volume overload in rats
Authors: Nakano Motoko , Kirimoto Tsukasa , Asaka Naomasa , Hayashi Yukio , Kanno Tomohiro , Miyake Hidekazu , Matsuura Naosuke
Published: August 2009

Abstract— We examined the effects of MET‐88 on haemodynamics and cardiac hypertrophy in rats with an aortocaval shunt (A‐V shunt). On the day of surgery, an A‐V shunt was produced by using an 18‐gauge needle in Wistar rats as described by Garcia and Diebold. MET‐88 and captopril were orally administered to rats 1 week after surgery, and the administration was continued for 3 weeks. Four weeks after the surgery, A‐V shunt‐operated rats had biventricular hypertrophy and higher right atrial pressure (RAP) and left ventricular end‐diastolic pressure (LVEDP) than sham‐operated rats. Compared with untreated A‐V shunt rats, those treated with MET‐88 showed significant attenuation of the development of left ventricular (LV) hypertrophy and of the increased LVEDP. Captopril‐treated A‐V shunt rats also failed to show increases in LV weight and LVEDP. In in vitro studies, MET‐88 had no effect on renin and angiotensin‐converting enzyme (ACE) activities in the plasma of normal rats. These results suggest that MET‐88 improved LV hypertrophy and LV dysfunction in rats with an A‐V shunt. Furthermore, the data indicate that the beneficial effects of MET‐88 may be attributed to some pathway, not involving the renin‐angiotensin system, such as myocardial energy metabolism, venous return, etc. We conclude that MET‐88 may be a novel agent for the therapy of chronic heart failure.
Antioxidant properties of aminoguanidine
Authors: Courderot‐Masuyer Carol , Dalloz Florence , Maupoil Véronique , Rochette Luc
Published: August 2009

Abstract— It is well known that aminoguanidine (AG) can diminish advanced glycosylation of proteins, which might be beneficial in preventing chronic diabetic complications. Recent reports suggested an inter‐relationship between glycosylation of protein and free radical damage. In the present study, we examined the free radical scavenging properties of AG. Electron paramagnetic resonance using the spin‐trap 5,5‐dimethyl‐1‐pyrroline N‐oxide (DMPO) was performed to determine the superoxide and hydroxyl radical scavenging abilities of AG. These experiments revealed that AG was an effective hydroxyl radical scavenger even though it expressed a direct inhibitory effect on the xanthine oxidase activity at high concentrations (AG ≥ 5 mM). In the second part of the study, allophycocyanin was used as an indicator of free radical mediated protein damage. In the assay, 2,2′‐azobis(2‐amidinopropane) hydrochloride (AAPH) was used as a peroxyl radical generator, and the loss of allophycocyanin fluorescence was monitored. The antioxidant effect of AG was expressed in oxygen‐radical absorbing capacity (ORAC), where one ORAC unit equals the net protection produced by 1 μM Trolox (a water soluble analogue of vitamin E) as a control standard. AG exhibited a significant dose‐dependent effect against free radical damage. These radical scavenging properties of AG may contribute to protective effects during glycation and explain the prevention of diabetic complications.
Fusobacterium necrophorum haemolysin stimulates motility of ileal longitudinal smooth muscle of the guinea‐pig
Authors: Kanoe M. , Toyoda Y. , Shibata H. , Nasu T.
Published: August 2009

Abstract— Fusobacterium necrophorum haemolysin (0.5‐3.1 mg protein/mL) dose‐dependently induced contractions of the isolated ileal longitudinal smooth muscle of the guinea‐pig. The haemolysin (3.1 mg protein/mL) ‐induced maximum contraction of 75% of the response to 60 mM K+ declined within 17 min and the muscles then demonstrated rhythmic contractions. Tetrodotoxin (3.1 × 10−6 M) had no effect on the contraction due to the haemolysin. After incubation in Ca2+‐free medium, the ileal response to the haemolysin was lost. Verapamil, a Ca2+ channel blocker, dose‐dependently inhibited the contraction to the haemolysin. The rabbit anti‐serum against F. necrophorum haemolysin inhibited the haemolysin‐induced contraction of ileal muscle. The bacterial haemagglutinin and the lipopolysaccharide had no effect on the response of ileal muscle. These findings suggest that the haemolysin‐induced direct stimulation of ileal motility dependant on Ca2+ influx will increase the probability of contact of F. necrophorum and ileal mucosa and could increase the chances of colonization for F. necrophorum.
Analysis of Helicobacter pylori binding site on HEp‐2 cells and three cell lines from human gastric carcinoma
Authors: Nishihara Katsushi , Nozawa Yoshihisa , Nomura Shuichi , Kitazato Kenji , Miyake Hidekazu
Published: August 2009

Abstract— Helicobacter pylori (H. pylori) is a pathogen responsible for chronic gastritis and peptic ulcer diseases. It colonises the gastric mucus layer and adheres to the gastric epithelial cell surface. As this adherence is the first step of infection, it is important to study the adherence mechanism. The aim of this study was to analyse the specific binding assay of H. pylori to HEp‐2 cells and three gastric phenotype cell lines, AGS, MKN‐45 and AZ‐521. H. pylori NCTC 11637 grown on agar plates was harvested and used in experiments. H. pylori was inoculated to pre‐cultured cell monolayers. Adhered bacteria were labelled with an anti‐H. pylori antibody and an FITC‐conjugated secondary antibody and quantified by using a fluorescent plate reader. Microbial adherence to HEp‐2 cells increased with incubation time and incubated concentration of H. pylori. No further increase was obtained with four or more hours of incubation or with a concentration of 4 × 107 bacteria/well or more. Scatchard analysis revealed a linear plot and the Bmax value was 88.3. Similar adherence patterns were obtained when AGS, AZ‐521 and MKN‐45 cells were used for adherence assays, but they had a lower binding affinity than HEp‐2 cells and AZ‐521. MKN‐45 cells had less receptors than HEp‐2 and AGS cells. In conclusion, H. pylori adhered to the cell surface could be quantified by this assay method. H. pylori adhesion to cell surfaces has a single population of binding site and one type of binding site on HEp‐2, AGS, AZ‐521 and MKN‐45 cells.
Effects of oxazepam and acetaminophen on cicletanine metabolism in rat hepatocytes and liver microsomes
Authors: Menard Christophe , Lamiable Denis , Vistelle Richard , Droy‐Lefait Marie‐Thérèse , Ratanasavanh Damrong
Published: August 2009

Abstract—Cicletanine, a racemic furopyridine derivative synthesized as racemate, is used as an antihypertensive agent. Its two enantiomers are involved in the pharmacological effects of the drug. Cicletanine is metabolized by conjugation enzyme systems (phase II) into sulfoconjugated or glucuroconjugated enantiomers. As oxazepam and acetaminophen are widely prescribed, especially to elderly patients, these two drugs may be co‐administered with cicletanine. The metabolic profile and the kinetics of biotransformation were studied by using rat hepatocytes and liver microsomes. Cicletanine was extensively metabolized by rat hepatocytes. More than 80% of the drug was biotransformed after a 3 h incubation. The formation of glucuroconjugated metabolites was characterized by the following kinetic parameters, i.e. Vmax= 2.05 ± 0.21 nmol/min/mg protein and Km= 287 ± 6.7 μM for (‐)‐cicletanine, and Vmax= 1.44 ± 0.12 nmol/min/mg protein and Km= 171 ±4.1 μM for (+)‐cicletanine. Oxazepam inhibited the glucuronidation of cicletanine in both rat hepatocytes and liver microsomes with a competitive‐type inhibition, i.e. Ki= 129 ± 7.5 and 152 ± 19.7 μM for (‐)‐cicletanine and (+)‐cicletanine, respectively. The co‐incubation of acetaminophen with cicletanine showed that only sulfoconjugation was inhibited in rat hepatocytes. Glucuronidation was not modified by acetaminophen. As natriuric activity is due to sulfoconjugated (+)‐cicletanine, acetaminophen could potentially modulate in vivo the pharmacological effect of cicletanine. The data of the in vitro study reported here suggested an interaction between cicletanine and oxazepam or cicletanine and acetaminophen. However, the clinical impact of such a drug interaction needs further evaluation.
Interspecies variability and drug interactions of clozapine metabolism by microsomes
Authors: Bun Hot , Disdier Béatrice , Aubert Claude , Catalin Jacques
Published: August 2009

Abstract— Cytochrome P450 expression in liver is influenced by several factors, including species, sex and strain. We compared metabolism formation of clozapine in different species (rat, mouse, guinea‐pig, dog, monkey and man) so as to choose between species to further validate interaction studies. Liver microsomes of male and female Sprague‐Dawley rats, hairless rats, OFI mice, Balb C mice and Dunkin‐Hartley albino guinea‐pigs, male beagle dogs, male cynomolgus monkeys and man were used to investigate in vitro metabolism of clozapine. This process was dependent on the presence of NADPH and on the presence of microsome protein. In addition, we observed the formation of desmethyl‐ and N‐oxide metabolites, with the rate of formation of each of these compounds varying with species, sex and strain of microsomes incubated. The desmethyl‐ and N‐oxide metabolites formed were statistically greater in male than in female rats, mice in the two strains studied, as well as for the guinea‐pigs. Levels of desmethyl clozapine formed were high for the rats and no significant difference in clozapine biotransformation was observed between Sprague‐Dawley and hairless rats. For man, the formation of metabolites of clozapine was comparable with guinea‐pig, dog and monkey. In addition, we screened the effect of 52 molecules, representative of 11 different therapeutic classes, on the metabolism of clozapine by rat liver microsomes. We found that most of the calcium channel blockers (diltiazem, felodipine, isradipine, lacidipine, nicardipine and nitrendipine), antifungals (ketoconazole, miconazole) and two anticancer drugs (paclitaxel, teniposide) caused more than 50% inhibition of clozapine metabolism in vitro. The extent of inhibition was increased in a concentration‐dependant manner. Complementary clinical and pharmacokinetic studies should be performed to confirm these results.
Prediction of methotrexate elimination after high dose infusion in children with acute lymphoblastic leukaemia using a population pharmacokinetic approach
Authors: Odoul Franck , Guellec Chantal Le , Lamagnère Jean‐Pierre , Breilh Dominique , Saux Marie‐Claude , Paintaud Gilles , Autret‐Leca Elisabeth
Published: August 2009

Abstract— High‐dose methotrexate (HD‐MTX) with leucovorin rescue is a component of therapy in children with acute lymphoblastic leukaemia. Since MTX toxicity is related to drug exposure, a monitoring of serum MTX concentrations at H24, H48, H72 and until the concentration is less than 0.2 μmol/L is commonly performed. However, a number of patients may reach concentrations of less than 0.2 μmol/L long before the next sampling is scheduled. The aim of our study was to develop a Bayesian method predicting the time at which MTX concentration reaches 0.2 μmol/L in order to decrease the number of samples drawn and to allow for a more rapid patient discharge. Methotrexate population parameters were estimated from a retrospective analysis of 60 infusions in 23 children and MTX concentrations were predicted from an independent set of 20 courses in 14 children with a Bayesian approach using either one (H48) or two (H24 and H48) samples. The following population parameters were obtained using a two‐compartment model: CL = 3.51 L/h (inter‐individual variability: 66%), Vd = 8.67 L (58%), k12 = 0.0044 h−1 (105%), k21 = 0.039 h−1 (25%). Clearance and Vd were found to increase with weight and age respectively. Both sampling schedules tested for the Bayesian estimation enabled accurate prediction of concentrations and provided satisfactory precision despite a small bias. When considering the ability to predict the time at which the threshold was reached, the one‐sample (H48) schedule gave the best results. We conclude that a sampling schedule involving only one sample and Bayesian parameter estimation may be able to predict the delay necessary to reach 0.2 μmol/L in each individual.
Cardiovascular responses to intrathecal dopamine receptor agonists in conscious DOCA‐salt hypertensive rats
Authors: Lahlou Saad
Published: August 2009

Abstract—Previous studies have demonstrated that in conscious deoxycorticosterone acetate (DOCA)‐salt hypertensive rats, the hypotensive action of intravenous (i.v.) bromocriptine, a selective dopamine D2receptor agonist, was mediated partly by peripheral and partly by spinal dopamine D2receptor stimulation, and that this effect was greater and longer‐lasting than that in uninephrectomized control rats. To determine whether this amplification results partly from a putative spinal hypersensitivity phenomenon, cardiovascular responses to intrathecal (i.t.) administration of apomorphine and quinpirole were studied in conscious, 4‐week DOCA‐salt hypertensive rats and compared with those in uninephrectomized control rats. In both groups, upper thoracic (T2‐T4) i.t. injections of apomorphine (9.1, 45.5 and 91.1 μg/rat) induced immediate and dose‐dependent decreases in mean aortic pressure (MAP) and heart rate (HR), while i.t. quinpirole (38.4 μg/rat) induced only bradycardia. Neither magnitude nor duration of these responses was enhanced in DOCA‐salt hypertensive rats when compared to control rats. In DOCA‐salt hypertensive rats, apomorphine‐induced hypotension and bradycardia remained unaffected by i.v. (500 μg/kg) pretreatment with domperidone, a selective dopamine D2receptor antagonist that does not cross the blood‐brain barrier. However, i.t. (40 μg/rat at T2‐T4) pretreatment with domperidone significantly reduced apomorphine‐induced hypotension, but fully suppressed bradycardia elicited by either apomorphine or quinpirole. These results demonstrated that in conscious DOCA‐salt hypertensive rats, intrathecally‐injected apomorphine or quinpirole decreased MAP and or HR through a spinal D2dopaminergic mechanism, as previously demonstrated in normotensive intact rats. Since both magnitude and duration of these responses were unchanged with respect to uninephrectomized control rats, enhancement of the hypotensive effect of intravenously‐administered bromocriptine in DOCA‐salt hypertensive rats does not appear to involve spinal dopamine D2receptors.
Valsartan and coronary haemodynamics in early post‐myocardial infarction in rats
Authors: Gervais Marianne , Richer Christine , Fornes Paul , De Gasparo Marc , Giudicelli Jean‐François
Published: August 2009

Abstract— Angiotensin 11 AT1 receptor blockade (AT1) has been shown to prolong survival in post‐myocardial infarction (MI) heart failure in rats. In this study, we investigated whether an early AT‐1‐induced improvement in coronary vasodilatation reserve (CVR) might be involved in this beneficial effect. Wistar rats with MI were treated daily and orally for 6 weeks with valsartan, 5 (MI‐V5) or 50 mg/kg (MI‐V50). MI‐controls and sham‐operated rats (S‐controls) received no treatment. Subsequently, systemic and coronary haemodynamics (at baseline and at maximal vasodilatation, CVR fluospheres) were investigated in the conscious state, and cardiac remodelling (hypertrophy and fibrosis) was assessed. As compared to MI‐controls, valsartan (5 mg/kg), had no effect on systemic haemodynamics or myocardial hypertrophy and fibrosis development, gave slightly improved basal left and right ventricular coronary flow and resistance values, but decreased left and right CVR values. Valsartan (50 mg/kg), decreased blood pressure (‐ 11%) and left ventricular end diastolic pressure (‐ 32%), limited the development of cardiac hypertrophy (‐ 19%) but not that of fibrosis, slightly improved basal left ventricular flow and resistance values but only the right ventricular CVR value was increased. We conclude that in rats with post‐MI, an early AT1 ‐induced improvement in coronary haemodynamics is not responsible for the long‐term survival prolongation observed. Furthermore, that cardiac hypertrophy was prevented whereas fibrosis was not, suggests that the latter is a pivotal determinant of CVR.
Differential properties of the optical‐isomers of pranidipine, a 1,4‐dihydropyridine calcium channel modulator
Authors: Hirano Takahiro , Mori Toyoki , Kido Masaru , Toide Kiyotaka , Ohura Makoto , Fujiki Hiroyuki , Orito Kensuke , Yoshida Kenji , Ikezono Katsumi , Sumida Takumi , Nakayama Natsuki , Yabuuchi Youichi
Published: August 2009

Abstract— Pranidipine is an optically‐active 1,4‐dihydropyridine (DHP) voltage‐dependent L‐type calcium channel inhibitor. Certain enantiomeric pairs display opposite effects, i.e., inhibition and activation of the calcium channel while others exhibit the same qualitative actions. We investigated pranidipine, a new DHP, using a paradigm of vascular smooth muscle reactivity. In isolated rat aorta, depolarized with 80 mM KCl, both isomers of pranidipine caused a right‐ward shift of the concentration‐contraction curves for extracellular Ca2+. The apparent pA2 values of the S‐isomer and R‐isomer were 10.03 and 8.36, respectively, providing evidence that the calcium channel blocking action of the S‐isomer was 50 times more potent than that of the R‐isomer. Antihypertensive actions of these two isomers studied in pentobarbital‐anaesthetized spontaneously hypertensive rats, revealed that the S‐isomer, at doses of 3–30 μg/kg i.v. decreased blood pressure in a dose‐dependent manner, while the R‐isomer had no effect on blood pressure at those doses. We conclude that the pair of enantiomers of pranidipine qualitatively display the same Ca2+channel blocking action and that neither isomer exhibits Bay K 8644‐like activation. Pranidipine may be useful in studies on the architecture of the DHP receptor ‘pocket’.
Fas‐induced death of a murine pulmonary epithelial cell line: modulation by inflammatory cytokines
Authors: Trifilieff Alexandre , Futjitani Yasushi , Coyle Anthony J. , Bertrand Claude
Published: August 2009

Abstract— Here we report that a murine pulmonary epithelial cell line (LA‐4) expresses Fas (CD95) under resting conditions. Exposure of untreated cells to an anti‐Fas monoclonal antibody induces apoptosis in a time‐ and dose‐dependent fashion as revealed by cell viability and by propidium iodide staining followed by FACS analysis. Fas surface expression was increased, in a time‐dependent fashion, by the inflammatory cytokines IL‐1β and TNF‐α. Other inflammatory mediators such as IFN‐γ or endothelin‐1 were without any effect. This increase in Fas expression was associated with an increase in sensitivity to anti‐Fas‐induced apoptosis of LA‐4 cells. IL‐4, which is known to induce CD95 resistance in other cell types, did not protect LA‐4 cells against anti‐CD95‐induced cell death. These results suggest that Fas‐induced apoptosis of epithelial cells may contribute to the epithelial shedding observed in asthmatic airways.
Protection by bilobalide of the ischaemia‐induced alterations of the mitochondrial respiratory activity
Authors: Janssens Dominique , Delaive Edouard , Remade José , Michiels Carine
Published: August 2009

Abstract— Ischaemia is a common feature of most vascular diseases. There is evidence from experimental and clinical studies that Ginkgo biloba extract protects tissues from ischaemia/reperfusion damages. Bilobalide seems to be responsible, at least in part, for this activity. However, the mechanism of the protection afforded by bilobalide is not yet known. In this work, the effects of bilobalide on mitochondrial respiration were investigated during liver and brain ischaemia, since mitochondria alteration is an early event in ischaemia‐induced damage. Bilobalide could prevent the decrease in respiratory activity induced by ischaemia in liver and in brain, both when glutamate/malate or succinate was used as substrate. Ischaemia decreased state 3 respiration rate and bilobalide prevented this decrease. While bilobalide was not able to prevent the decrease in adenine translocase activity, it protected complex I activity. Bilobalide allows mitochondria to maintain their respiratory activity in ischaemic conditions by protecting complex I and probably complex III activities. Hence, the energetic pool of tissues is preserved during the ischaemic period as well as its viability. This mechanism provides a possible explanation for the anti‐ischaemic properties of bilobalide and of Ginkgo biloba extract in therapeutic interventions.
Subtypes of adenosine receptors on pancreatic exocrine secretion in anaesthetized dogs
Authors: Iwatsuki K.
Published: August 2009

Abstract—Characterization of adenosine receptor subtypes was examined on the canine exocrine pancreas using selective adenosine receptor agonists and antagonists in the isolated and blood‐perfused pancreas of anaesthetized dogs. Each drug was injected intra‐arterially in a single bolus fashion. Graded doses of CGS21680 (1–300 nmol/kg), a selective adenosine A2Areceptor agonist, produced dose‐dependent increases in the secretory rate of pancreatic juice, with a maximum effect at approximately 30 nmol/kg. However, CPA (1–300 nmol/kg), a selective adenosine A, receptor agonist, did not cause the pancreatic secretion. CGS21680 (3–30 nmol/kg) and secretin (0.01–0.03 pmol/kg) increased the bicarbonate concentration in pancreatic juice and decreased the protein concentration. CCK‐8 (0.1–0.3 pmol/kg) increased the protein concentration but did not alter the bicarbonate concentration. DMPX (5–50 nmol/kg), a weak adenosine A2Areceptor antagonist, caused a progressive parallel shift to the right in the dose‐response curve for CGS21680‐induced pancreatic secretion without changes in the maximal response. DPCPX (100 nmol/kg), a selective A, adenosine receptor antagonist, did not antagonize the CGS21680‐induced pancreatic secretion. Schild analysis of the data indicated that the apparent pA2value for DMPX was 8.3 using CGS21680 as the agonist. The slope of the Schild regression line was not different from 1. When a phosphodiesterase IV inhibitor rolipram (0.1 nmol/kg) was added, pancreatic secretion induced by CGS21680 (10 nmol/kg) and secretin (0.03 pmol/kg) were potentiated, but not that of CCK‐8 (0.3 pmol/kg). These results suggest the existence of adenosine A2Areceptors in the exocrine cells of the dog pancreas involved in the water and bicarbonate secretory response.
Beraprost sodium‐fluindione combination in healthy subjects: pharmacokinetic and pharmacodynamic aspects
Authors: Warot Dominique , Berlin Ivan , Aymard Guy , Ankri Annick , Fabry Caroline , Besse Bruno , Lechat Philippe , Diquet Bertrand
Published: August 2009

Abstract— Beraprost sodium (BPS), an orally active PGI2 (prostaglandine I2) analogue possesses vasodilatating and platelet aggregation inhibiting properties. It is being developed in peripheral arterial occlusive disease. As in future clinical practice BPS might be co‐prescribed with oral anticoagulants, we investigated its interaction with fluindione, a vitamin K antagonist in healthy subjects in a randomised, double‐blind, placebo‐controlled, crossover study. Twelve healthy Caucasian male subjects randomly received BPS 40 μg t.i.d. or placebo for 3 days. There was a 7 day wash out between the two treatment periods. On day 3 of each treatment, the subjects ingested concomitantly a single oral dose of 20 mg of fluindione. The main assessment criterion was fluindione's pharmacokinetics. Secondarily, pharmacodynamic measurements of coagulation (prothrombin time, and International Normalised Ratio, INR) and platelet function (in vitro closure time assessed by PFA‐100×) were performed. Fluindione was assayed by HPLC with UV detection up to 96 h post‐drug. No statistical difference could be evidenced on any fluindione pharmacokinetic parameters between BPS and placebo phases: t1/2 (h): 35.9 (8.2) vs. 34.0 (4.2) [90% CI 105.8 (95.5–116.2)]; Tmax (h): 2.0 (0.5–6.0) vs. 4.0 (0.5–6.0) [90% CI 136.4 (70.7–208.9)]; Cmax (mg/L): 3.1 (0.6) vs. 2.9 (0.5) [90% CI 94.1 (85.8–103.2)]; AUC 0‐inf (mg/h/L): 117.0 (31.5) vs. 113.9 (33.8) [90% CI 97.6 (87.5–108.8)]. The studied doses of BPS did not affect platelet function, at least as assessed by the in vitro platelet function testing. Twenty milligrams of fluindione marginally modified the PT ratio and INR, however, no statistically significant difference was found between BPS and placebo phases. In conclusion, a 3 day regimen of BPS 40 μg t.i.d. by oral route does not seem to affect pharmacokinetic parameters of a fluindione 20 mg single dose.
Effects of non‐ionic monomeric and dimeric iodinated contrast media on renal and systemic haemodynamics in rats
Authors: Idée Jean‐Marc , Lancelot Eric , Berthommier Christine , Couturier‐Goulas Valérie , Vazin Véronique , Corot Claire
Published: August 2009

Abstract— Non‐ionic dimeric contrast media (CM) are a new class of CM which are iso‐osmolar with plasma. The aim of this study was to investigate their effects on systemic and renal haemodynamics. The non‐ionic dimeric CM iodixanol and the non‐ionic monomeric agent iobitridol (both at a dose of 1600 mgl/kg) were compared in terms of their effects on systemic blood pressure (BP) and renal blood flow (RBF) in two strains of rats (Wistar and Sprague Dawley). Iodixanol significantly lowered BP in Wistar rats (− 33 ± 9% of baseline, 10 min post‐injection, P < 0.001 vs. saline and iobitridol). Iobitridol had virtually no effect on BP. Iobitridol and iodixanol significantly decreased RBF. This effect was more marked following injection of the dimer rather than the monomer (iodixanol: − 32 ± 13%, iobitridol: − 20 ± 4% of baseline at 16 min, P < 0.05). For both agents, RBF was still decreased 50 min following injection (iodixanol: − 30 ± 11% and iobitridol: − 20 ± 5% of baseline). Iodixanol also decreased RBF in Sprague Dawley rats, while BP remained unchanged. This suggests that changes in BP/RBF autoregulation do not account for the renal haemodynamic effects of this agent. When measured 2 h following injection, the iodixanol‐induced renal hypoperfusion was still detectable (− 29% vs. saline‐treated rats), although not significant (P = 0.06). This effect was no longer observed 4 h following injection. Increasing the saline infusion rate (18 mL/h vs. 2 mL/h) during the experiment did not significantly decrease the effects of iodixanol on BP and RBF in Wistar rats. In spite of its iso‐osmolality, iodixanol, a non‐ionic dimeric CM. depressed RBF and BP significantly more than iobitridol, a monomeric non‐ionic agent, in Wistar rats. This effect was long‐lasting and was not alleviated by increasing the hydration rate.
Detection of salicylate and its hydroxylated adduct 2,3‐dihydroxybenzoic acid in glutamate neurotoxicity and the effects of verapamil and ryanodine in rats
Authors: Gepdiremen Akçahan , Singh Gulzar , Marsden Charles A.
Published: August 2009

Abstract— It has been suggested that salicylate hydroxylation can be used to detect hydroxyl radical formation in vivo. In the present study we investigated the effects of verapamil and/or ryanodine on salicylate (SA) and its hydroxylated adduct; 2,3‐dihydroxybenzoic acid (2,3‐DHBA) levels in glutamate induced neurotoxicity of whole rat brains. To detect SA and 2,3‐DHBA, an HPLC‐EC/UV method was used. Retention time was found to be 3.9 min for 2,3‐DHBA and 12.0 min for SA. Verapamil at 10−5and 10−7and ryanodine at 10−5M concentrations were found to have a significant decreasing effect on this degradation induced by glutamate. This was the highest dose for ryanodine tested. As an L‐type voltage dependent calcium channel blocker, verapamil was found ineffective at 10 −4, 10 −6and 10 −8M concentrations. Surprisingly, none of the combined application groups (verapamil + ryanodine) was found effective on SA hydroxylation. As a result, ryanodine was effective only at the highest dose, while verapamil exerts its effect in a dose dependent fashion as reported before in the literature.
Comparison of the efficacy and safety of losartan (50–100 mg) with the T‐type calcium channel blocker mibefradil (50–100 mg) in mild to moderate hypertension
Authors: Chung Oliver , Hinder Markus , Sharma Arya M. , Bönner Gerd , Middeke Martin , Platon Julian , Unger Thomas
Published: August 2009

Abstract— The objective of this study was to compare the antihypertensive efficacy and safety of losartan and mibefradil. 324 outpatients (57 ± 9.2 years) with mild to moderate hypertension were randomly allocated in a double‐blind fashion to receive 50 mg of losartan or mibefradil once daily p.o. for 6 weeks after 2 weeks of placebo run‐in. Titration was then forced to 100 mg of losartan or mibefradil for an additional 6 weeks. Patients were assessed at baseline, 6 and 12 weeks. The primary efficacy variable was change in predose sitting diastolic (SDBP) and systolic (SSBP) blood pressure at 12 weeks. Secondary variables included change in mean 24‐hour ambulatory blood pressure and comparison of safety and tolerability. Both treatments lowered SSBP and SDBP at 6 and 12 weeks (week 6: mibefradil −14/−9 mm Hg; losartan −12/−7 mm Hg) (p < 0.001). The primary objective, a difference between treatments in reduction of SSBP and SDBP at week 12 could be demonstrated (mibefradil −22/−16 mm Hg; losartan −16/−10 mm Hg) (p = 0.003 and P = 0.001, respectively). Twenty‐four‐hour SBP and 24‐hour DBP were reduced (p < 0.001) within each treatment group at weeks 6 and 12. The secondary objective, a difference between treatments in reduction of 24‐hour blood pressure at week 12 could be demonstrated (P < 0.001). Twenty‐four‐hour heart rate was lowered in the mibefradil group at weeks 6 and 12 (P < 0.001). Responder rates at 6 and 12 weeks were 56.2% and 78.5% for mibefradil versus 56.1% and 55.3% for losartan (P = 0.001). Both treatments were equally well tolerated. This study demonstrates that 50 mg losartan is comparably effective to 50 mg mibefradil in the treatment of mild to moderate hypertension with 100 mg mibefradil being more potent than losartan.
Inverse agonism at heptahelical receptors: concept, experimental approach and therapeutic potential
Authors: Daeffler Laurent , Landry Yves
Published: August 2009

Abstract— Inverse agonists (negative antagonists) are ligands that stabilize the inactive conformation (R) of receptors according to the two‐state receptor model. The active conformation (R*) of heptahelical receptors, i.e. G protein‐coupled receptors, has high affinity for G proteins. According to ternary complex models of receptor activation, the R*G complex is in equilibrium with R + G, with spontaneous activity in the absence of agonist. Inverse agonists, having a higher affinity for R, shift R*G towards R + G, decreasing the spontaneous activity of receptors. Agonists have the opposite effect, with a higher affinity for R*. Neutral antagonists have the same affinity for R and R*and compete for both agonists and inverse agonists. Inverse agonists have been recently proposed for a variety of heptahelical receptors. Methods to detect inverse agonists among antagonists are based on the determination of ligand affinity at R and R*with binding experiments, and on the modulation of G protein activity (GTP binding and hydrolysis) or of effector activity. Receptor inverse agonists, but also G protein antagonists and GTPase inhibitors, decrease spontaneous G protein activity corresponding to R*G. Receptor agonists, G protein agonists and GTPase inhibitors increase effector basal activity, but receptor inverse agonists decrease it. The therapeutic potential of inverse agonists is proposed in human diseases ascribed to constitutively active mutant receptors and may be extended to diseases related to wild‐type receptor over‐expression leading to the increase of R*. Some of the therapeutic effects of presently used receptor antagonists may be related to their inverse agonist properties. Inverse agonists lead to receptor upregulation, offering new approaches to tolerance and dependence to drugs.
Hypertension in transgenic (mREN2)27 rats is not associated with the presence of B1 receptors
Authors: Lagneux Caroline , Joyeux Marie , Bricca Giampierro , Demenge Pierre , Ribuot Christophe
Published: August 2009

Abstract— B1 receptors are inducible receptors expressed only in stressful conditions. The aim of this study was to determine if, in (mREN2)27 transgenic rats, hypertension is associated with the presence of B1 receptors in the cardiovascular system and if a heat stress inducible effect is preserved during hypertension. Age‐matched (16 weeks old) heterozygous hypertensive transgenic (mREN2)27 rats (HT rats) and the normotensive control animals (homozygous Sprague‐Dawley rats, NT rats) were used. The study was conducted in two parts: in the first part the responsiveness of B1 receptors was studied in rats submitted to heat stress (42 °C rectal temperature, 20 min) or sham anaesthesia 24 h before, by recording changes in isometric tension in aortic rings in response to [des‐Arg9]‐bradykinin, a B1 receptor agonist. In the second part, we studied whether B1 receptor mRNA was present in aorta, heart and kidneys, using a semi‐quantitative RT‐PCR technique. [des‐Arg9]‐Bradykinin induced a concentration‐dependent relaxation of aortic rings only from animals submitted to prior heat stress. This response was significantly higher in aortic rings from heat stressed HT rats than from heat stressed NT ones. B1 receptor mRNA was undetectable in organs from rats not submitted to heat stress but they were present 5 h after heat stress in aorta, heart and kidneys from both NT and HT rats. In conclusion, arterial hypertension observed in (mREN2)27 rats is not associated with the presence of B1 receptors. However, after heat stress, we observed an increase in responsiveness from HT rat aortas compared to NT ones.
Monitoring of the intracellular activation of 5‐fluorouracil to deoxyribonucleotides in HT29 human colon cell line: application to modulation of metabolism and cytotoxicity study
Authors: Ciccolini Joseph , Peillard Laurent , Aubert Claude , Formento Patricia , Milano Gérard , Catalin Jacques
Published: August 2009

Abstract— An HPLC method was developed for in vitro detection and monitoring of intracellular metabolites of [3H]‐5‐fluorouracil (FUra). Results showed a preferential activation of FUra to ribonucleoside and ribonucleotide derivatives (FURd, FUMP, FUDP and FUTP) in the human colorectal HT29 cell line. We screened various agents so as to determine if they could act as modulators of metabolism and/or toxicity of FUra by reversing the activation pathway of FUra from ribo‐ to deoxyribonucleotides, thus enhancing FdUMP formation. Different drugs (efflux inhibitors, catabolism inhibitors and enzymatic cofactors) were tested for enhancement of cytotoxicity when associated with FUra. The most promising agents were further studied by assessment of their ability to modulate intracellular activation of FUra to enhance thymidylate synthase (TS) inhibition by FUra and to increase the subsequent induction of apoptosis. 2′‐Deoxyinosine (d‐Ino), a deoxyribose 1‐phosphate donor increasing thymidine phosphorylase activity, stood out as the best modulating agent we screened. Results showed an up to 30‐fold increase of cytotoxicity along with a stronger inhibition of TS when FUra was associated with d‐Ino, while FUra alone exhibited a lesser effect on TS activity. Besides, HPLC analysis revealed a compléte reversal of the activation pathway of FUra, thus leading to an intracellular accumulation of deoxyribonucleotides. Assessment of cell cycle distribution showed a marked increase (+480%) of apoptosis in cells exposed to FUra/d‐Ino compared to FUra alone. The HPLC method we developed is a convenient tool for assessing to what extent modulators will actually act on the intracellular activation of FUra. This study confirms the potentiality of d‐Ino to modulate FUra metabolism in vitro. It proved to be an agent able to orientate the mechanism of action of FUra towards the inhibition of TS in cells where the normal activation pathway of the drug does not result in the intracellular accumulation of the active metabolite FdUMP.
Gastroduodenal tolerability of medium dose enteric‐coated aspirin: a placebo controlled endoscopic study of a new enteric‐coated formulation versus regular formulation in healthy volunteers
Authors: Bondon Hugues , Barbier Jean‐Philippe , Mahé Isabelle , Deverly Anne , Kolsky Hélène , Bergmann Jean‐François
Published: August 2009

Abstract— We compared, in a cross‐over study, the toxicity of 300 mg enteric‐coated aspirin with regular aspirin used for the prevention of cardiovascular events. In terms of endoscopic haemorragic lesions, enteric‐coated aspirin is less gastrotoxic than regular aspirin.
Tramadol relieves thermal hyperalgesia in rats with chronic constriction injury of the sciatic nerve
Authors: Tsai Yu‐Chuan , Sung Yen‐Hui , Chang Pei‐Jung , Kang Fu‐Chi , Chu Koung‐Shing
Published: August 2009

Abstract—The present study was designed to test whether tramadol is effective in the control of neuropathic pain in rats. Chronic constriction injury (CCI) of the sciatic nerve was induced over the left hind limb in male Sprague‐Dawley rats. Identical surgery was performed on the opposite side except that the sciatic nerve was not ligated (sham surgery). Paw withdrawal latency (PWL) to heat was tested for each hind paw 1 day before surgery and on the 4th day after surgery to ensure the development of thermal hyperalgesia. In the acute treatment groups, saline or tramadol was administered subcutaneously at doses of 10, 20 or 30 mg/kg, and PWLs were measured 30, 60, 90, 120, 150 and 180 min after treatment. In the semi‐chronic treatment groups, continuous systemic administration of tramadol 40 mg/kg/day or saline for 7 days was provided at a uniform rate via osmotic mini pumps. Tramadol reversed PWL in a dose‐dependent manner in the acute treatment groups. PWLs were significantly reversed at 2 days after tramadol infusion, and this effect was sustained throughout the remainder of the treatment period in comparison with the saline group. Tramadol also resulted in a decreased sensitivity to thermal stimulus on the sham limb both in acute and semi‐chronic administration. We conclude that both acute and semi‐chronic tramadol treatment relieves thermal hyperalgesia effectively in rats with CCI of the sciatic nerve. This indicates that tramadol shows promise as a potential treatment for relief of neuropathic pain in humans.
Characterization and mechanisms of the cardiovascular and haemodynamic alterations induced by scorpion venom in rats
Authors: Zeghal Khaled , Sahnoun Zouhir , Guinot Marine , Richer Christine , Giudicelli Jean‐François
Published: August 2009

Abstract—The scope of this work was to investigate the nature, chronology and mechanisms of the cardiovascular disorders induced by scorpion envenoniation. Anaesthetized rats were instrumented for measurement of cardiac output (CO), renal (RBF) and muscular (HBF) blood flows (pulsed Doppler flowmetry), blood pressure, heart rate and dP/dt.Buthus occitanusvenom (BO) was administered intravenously in the absence/presence of different pre‐treatments. BO dose‐dependently (150–300 μg/kg) increased blood pressure, dP/dt, total peripheral (TPR), renal (RVR) and muscular (HVR) vascular resistances, and decreased CO, RBF and HBF. Recovery occurred after 150 but not after 300 μg/kg. BO, 600 μg/kg, produced qualitatively similar effects but arrhythmias developed and mortality increased. Pre‐treatment with phentolamine prevented the rises in TPR, RVR, HVR and blood pressure and the decreases in CO, RBF and HBF induced by BO, 300 μg/kg. Pre‐treatment with propranolol prevented the rise in dP/dt and the occurrence of arrhythmias and limited the rise in RVR and the drop in RBF induced by BO, 300 μg/kg. Phentolamine, propranolol and their combination also prevented BO, 600 μg/kg‐induced mortality. Other pre‐treatments (bosentan, losartan, diltiazem, mepyramine) were almost ineffective vs. BO effects. Finally, BO, 300 μg/kg, induced a 30–40‐fold increase in plasma epinephrine and norepinephrine levels, but no change in plasma endothelin‐1 levels. Thus in anaesthetized rats, the pattern of the cardiac and systemic and regional haemodynamic effects of BO is typically that of and results from catecholamine outpouring‐induced α‐ and β‐adrenoceptor stimulation.
Identification of opioid receptors in the sympathetic and parasympathetic nerves of guinea‐pig atria
Authors: Hung Chi‐Feng , Chang Wei‐Luen , Liang Hsiu‐Chuan , Su Ming‐Jai
Published: August 2009

Abstract—The opioid receptor subtypes of autonomic nerves of guinea‐pig atria were elucidated by monitoring the effects of selective opioid receptor agonists on the negative and positive inotropic responses associated with the stimulation of the parasympathetic and sympathetic nerves, respectively. The positive inotropic effect, evoked by electrical field stimulation (2 Hz) was strongly reduced by the selective OP2‐opioid receptor agonists U‐50488 and U‐69593, but partly by the OP3‐opioid receptor agonist morphine. This effect of U‐50488 and U‐69593 were reversed by the selective OP2‐opioid receptor antagonist nor‐BNI. The effect of morphine was partly reversed by naloxone, whereas OP1‐opioid receptor agonists, BW373 U86 and DPDPE, were ineffective. On the other hand, the negative inotropic response to electrical field stimulation was not affected by opioid receptor agonists. These results suggest that the noradrenaline release from cardiac sympathetic nerves of guinea‐pig could be modulated, mainly by the OP2‐opioid receptor, however, the acetylcholine release from cardiac parasympathetic nerves is not modulated by opioid receptors.
Interaction of extracellular albumin and intravenous anaesthetics, etomidate and propofol, on calcium signalling in rat airway smooth muscle cells
Authors: Belouchi Nour‐Eddine , Roux Etienne , Savineau Jean‐Pierre , Marthan Roger
Published: August 2009

Abstract— It has been shown in vitro that general anaesthetics modify airway responsiveness via, at least partially, a direct inhibitory effect on calcium signalling in airway smooth muscle cells. However, in vivo, these anaesthetic compounds bind serum proteins. We have investigated the effect of exposure to extracellular albumin of freshly isolated airway smooth muscle cells on the propofol‐ and etomidate‐induced inhibitory effect on calcium signalling. [Ca2+]i was measured by microspectrofluorimetry in rat isolated tracheal smooth muscle cells using the fluorescent dye indo‐1. Propofol (3 × 10−4M) and etomidate (10−4M) were the lowest ‘effective’ concentrations that altered the [Ca2+]i response. This alteration consisted of a decrease in both the amplitude of the [Ca2+]i peak (from 358 ± 13 nM to 65 ± 15 and 108 ± 27 nM for propofol and etomidate, respectively) and the percentage of responding cells (from 80% to 37 and 25%, respectively) in response to the low concentration of ACh and a decrease in the Ca2+oscillation frequency (from 9.9 ± 0.3 min−1to 4.7 ± 0.4 and 6.9 ± 0.4 min−1, respectively) in response to the high concentration of ACh. Increasing the concentration of albumin reduced the inhibitory effect of etomidate and propofol on the [Ca2+]i response to ACh. When extracellular albumin concentration was kept constant (20 g/L), increasing the concentration of etomidate by one log restored its inhibitory effect on the calcium signal. This study indicates that increasing the concentration of extracellular albumin reduces the inhibitory effect of intravenous anaesthetics on calcium signalling in airway smooth muscle cells. This report suggests that, in extrapolating in vitro dose‐response relationships to those from in vivo conditions, the effect of the concentration of extracellular protein can be estimated.
Differentia] transcriptional regulation of endothelin‐1 by immunosuppressants FK506 and cyclosporin A
Authors: Marsen Tobias A. , Weber Frank , Egink Guido , Suckau Gudrun , Baldamus Conrad A.
Published: August 2009

Abstract— Calcineurin antagonists FK506 and CsA, administered to treat organ allograft rejection, exert specific effects on renal vasoconstriction and nephrotoxicity, possibly due to endogenous vasoconstrictor release such as ET‐1. We investigated contribution of FK506 and CsA on regulation of prepro ET‐1 gene transcription in HUVEC. To conclude on transcriptional regulation, ET‐1 mRNA levels were quantified by Northern blot analysis upon stimulation with calcineurin antagonists, and newly transcribed luciferase gene, placed under the control of the rat ET‐1 promoter, was quantified by reporter gene assays, where luciferase activity reflects ET‐1 promoter activation. Calcium fluorometry was employed to examine calcium dependency of ET‐1 promoter‐dependent gene transcription. Northern blot analysis shows differential induction of prepro ET‐1 mRNA in favour of CsA over FK.506. Likewise, luciferase assays demonstrate stronger ET‐1 promoter‐dependent stimulation of the reporter gene by CsA than by FK506. Transcription of prepro ET‐1 gene upon stimulation with both calcineurin antagonists is regulated by intracellular calcium levels. Lack of extra‐ or intracellular calcium prevents ET‐1 promoter‐dependent gene transcription and ET‐1 mRNA induction. These observations demonstrate that calcineurin antagonists FK506 and CsA differ in quality to induce transcription of prepro ET‐1 in HUVEC via calcium‐dependent nuclear signalling events. To examine the contribution of ET‐1 in nephrotoxicity upon CsA and FK506 immunosuppression the availability of endothelin receptor antagonists or endothelin converting enzyme inhibitors is required.
Pharmacological elements in clinical application of synthetic peptides
Authors: Lauta Vito Michele
Published: August 2009

Abstract— The research carried out on the biological properties of synthetic peptides and the possibility of obtaining them in adequate amounts through the recombinant DNA technology allows their use as therapeutical agents. Procedures following the synthesis of peptides must be performed in order to verify their structure, conformation, immunogenicity and biological activity and to make them suitable for clinical applications. The size of synthetic peptides together with some modifications such as amidation, acetylation and sulfatation must be taken into consideration as they may have a significant impact on half‐life, stability and biological activity. Endothelial, epithelial and enzymatic interference which may hinder the absorption of drugs must be evaluated in order to choose the most appropriate route of administration. The considerable bioavailability related to the intravenous route, the effectiveness of the circulation of the intramuscular route and the possibility of reaching specific targets by the intra‐arterial route must also be taken into consideration. There is the possibility of applying transdermal therapeutic systems and transdermal iontophoresis only for peptides of low molecular weight. Among synthetic peptides provided with antianaemic activity, erythropoietin, growth factors and interleukin 3 must be mentioned because of their effectiveness both in optimal stimulation of myelopoiesis after chemotherapy or bone‐marrow transplantation and in the treatment of anaemia occurring during chronic renal failure. Furthermore, interferon alpha was shown to be one of the most used synthetic peptides provided with antiviral and antineoplastic activity. Remarkable results have been obtained in the treatment of chronic hepatitis C, haematological malignancies and some solid tumours. More recently, interleukin 2 has been tested in the treatment of melanoma and renal cancer, inducing a reasonable proportion of overall response rate. Finally, the antagonist of gonadotropin‐releasing‐hormone may be regarded as effective agent both in the treatment of prostate cancer and in the inhibition of luteinizing‐hormone surges during controlled ovarian stimulation. Toxic side effects can be related to the administered dose as well as to metabolites derived from bacteria in which peptides have been synthesized.