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Crossover Experiment (crossover + experiment)
Selected AbstractsNo effect of experimental occlusal interferences on pressure pain thresholds of the masseter and temporalis muscles in healthy womenEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2006A. Michelotti It has been suggested that occlusal interferences may lead to pain and tenderness of the masticatory muscles. Tender jaw muscles are more sensitive to pressure pain, as assessed by means of pressure algometry. We tested the effects of occlusal interferences on the pressure pain threshold of the jaw muscles by means of a double-blind randomized crossover experiment carried out on 11 young healthy females. Golden strips were glued either to an occlusal contact area (active interference) or to the vestibular surface of the same tooth (dummy interference) and left for 8 d each. Pressure pain thresholds of the masseter and anterior temporalis muscles were assessed under interference-free, dummy-interference and active-interference conditions. The results indicated that the application of an active occlusal interference, as used in this study, did not influence significantly the pressure pain thresholds of these muscles in healthy individuals. [source] Two-thumb vs Two-finger Chest Compression in an Infant Model of Prolonged Cardiopulmonary ResuscitationACADEMIC EMERGENCY MEDICINE, Issue 10 2000Michele L. Dorfsman MD Abstract. Objective: Previous experiments in the authors swine lab have shown that cardiopulmonary resuscitation (CPR) using two-thumb chest compression with a thoracic squeeze (TT) produces higher blood and perfusion pressures when compared with the American Heart Association (AHA)-recommended two-finger (TF) technique. Previous studies were of short duration (1-2 minutes). The hypothesis was that TT would be superior to TF during prolonged CPR in an infant model. Methods: This was a prospective, randomized crossover experiment in a laboratory setting. Twenty-one AHA-certified rescuers performed basic CPR for two 10-minute periods, one with TT and the other with TF. Trials were separated by 2-14 days, and the order was randomly assigned. The experimental circuit consisted of a modified manikin with a fixed-volume arterial system attached to a neonatal monitor via an arterial pressure transducer. The arterial circuit was composed of a 50-mL bag of normal saline solution (air removed) attached to the manikin chest plate and connected to the transducer with a 20-gauge intravenous catheter and tubing. Rescuers were blinded to the arterial pressure tracing. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were recorded in mm Hg, and pulse pressures (PPs) were calculated. Data were analyzed with two-way repeated-measures analysis of variance. Sphericity assumed modeling, with Greenhouse-Geisser and Huynh-Feldt adjustments, was applied. Results: Marginal means for TT SBP (68.9), DBP (17.6), MAP (35.3), and PP (51.4) were higher than for TF SBP (44.8), DBP (12.5), MAP (23.3), and PP (32.2). All four pressures were significantly different between the two techniques (p , 0.001). Conclusion: In this infant CPR model, TT chest compression produced higher MAP, SBP, DBP, and PP when compared with TF chest compression during a clinically relevant duration of prolonged CPR. [source] Putting density dependence in perspective: nest density, nesting phenology, and biome, all matter to survival of simulated mallard Anas platyrhynchos nestsJOURNAL OF AVIAN BIOLOGY, Issue 3 2009Johan Elmberg Breeding success in ground-nesting birds is primarily determined by nest survival, which may be density-dependent, but the generality of this pattern remains untested. In a replicated crossover experiment conducted on 30 wetlands, survival of simulated mallard nests was related to "biome" (n=14 mediterranean and 16 boreal wetlands), breeding "phenology" (early vs late nests), and "density" (2 vs 8 nests per 225 m shoreline). Local abundances of "waterfowl", "other waterbirds", and "avian predators" were used as covariates. We used an information-theoretic approach and Program MARK to select among competing models. Nest survival was lower in late nests compared with early ones, and it was lower in the mediterranean than in the boreal study region. High-density treatment nests suffered higher depredation rates than low-density nests during days 1,4 of each experimental period. Nest survival was negatively associated with local abundance of "waterfowl" in the boreal but not in the mediterranean biome. Effect estimates from the highest-ranked model showed that nest "density" (d 1,4) had the strongest impact on model fit; i.e. three times that of "biome" and 1.5 times that of "phenology". The latter,s effect, in turn, was twice that of "biome". We argue that our study supports the idea that density-dependent nest predation may be temporally and spatially widespread in waterfowl. We also see an urgent need for research of how waterfowl nesting phenology is matched to that of prey and vegetation. [source] Plasma achiral and chiral pharmacokinetic behaviour of intravenous oxfendazole co-administered with piperonyl butoxide in sheepJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 1 2002S. SÁNCHEZ Co-administration of piperonyl butoxide (PB) potentiates fenbendazole (FBZ) in small ruminants. The resultant increase in bioavailability of FBZ and its metabolite oxfendazole (OFZ) has important implications for the efficacy of these drugs against benzimidazole (BZD)-resistant strains of Teladorsagia circumcincta. This study evaluated the racemic (achiral) and enantiomeric (chiral) plasma disposition kinetics of OFZ and its metabolites after the co-administration of PB and OFZ in sheep. Six 6,8-month-old, parasite-free, female Dorset sheep (30,40 kg) were used in a two-phase crossover experiment. In phase I, three sheep received 30 mg/kg PB orally, followed by a single intravenous (i.v.) injection of OFZ at 5 mg/kg. The other three animals were treated similarly except that 5 mL of water replaced PB. In phase 2, treatments for the two groups were reversed and were given 14 days after the initiation of phase I. Three analytes OFZ, FBZ and fenbendazole sulphone (FBZSO2) were recovered in plasma up to 48 h post-treatment in both experimental groups. Achiral and chiral pharmacokinetic (PK) profiles for OFZ, after the co-administration of PB, were characterized by a significantly greater area under the concentration,time curve (AUC) and a longer mean residence time (MRT). Chiral OFZ distribution ratios were comparable in both treatment groups. Piperonyl butoxide treatment markedly influenced the plasma PK profiles for FBZ and FBZSO2 following OFZ administration. Production of FBZ was enhanced as reflected by increased (> 60%) AUC, delayed Tmax and a significantly delayed (> 45%) elimination (t˝el). Although AUC values for FBZSO2 were not significantly different between groups, this metabolite was depleted more slowly from plasma (t˝el > 60% and MRT > 42%) following PB treatment. This study demonstrated that PB co-administration is associated with an inhibition of OFZ biotransformation, as evidenced by the significantly higher plasma concentrations of OFZ and FBZ, and this could have important implications in terms of antiparasite therapy against BZD-resistant parasite strains. [source] Liquid chromatographic,mass spectrometry analysis and pharmacokinetic studies of a novel rabeprazole formulation, sterile powder for injection, in dogs and ratsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2007Feng Shao Abstract Rabeprazole is among the most potent proton pump inhibitors (PPI) identified to date and it has been demonstrated that it is effective in such diseases as gastroesophageal reflux disease (GERD), duodenal ulcer and gastric ulcer. There is currently interest in developing a new formulation: rabeprazole sterile powder for injection (RSPI). This investigation was conducted to evaluate the preclinical pharmacokinetics of RSPI in rats and at the same time a comparative study was carried out in dogs between RSPI and Pariet® tablets using liquid chromatographic,mass spectrometry analysis. The liquid chromatographic,mass spectrometry method was first conducted and validated as being specific, and having accuracy, precision, sensitivity and a satisfactory recovery. After intravenous administration of RSPI (i.v.: 2, 6 and 18 mg/kg) to rats, no significant dose-dependency was found in the CL (4.20,5.72 l/h/kg), Varead (0.94,1.32 l/kg), dose-normalized AUC (197.20,245.82 µg/l*h based on 1 mg/kg) and t1/2 (p>0.05). In the dog, a randomized, open-label, crossover experiment was carried out to show that the mean area under the plasma concentration-time curve (AUC0,,) after i.v. administration of RSPI was at least four times larger than that following oral administration of Pariet® tablet at an equivalent dose but the elimination half-life of these two formulation was similar (p>0.05). The results showed that the pharmacokinetics of RSPI was linear (r2 = 0.98) in the dose range 2,18 mg/kg and the RSPI had a much higher AUC0,, and similar t1/2 values compared with the enteric-coated tablet. Copyright © 2007 John Wiley & Sons, Ltd. [source] Synthesis, Structure and Reactivity of Homo- and Heterobimetallic Complexes of the General Formula [Cp*Ru(,-Cl)3ML] [LM = (arene)Ru, Cp*Rh, Cp*Ir]EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2006Laurent Quebatte Abstract The homo- and heterobimetallic complexes [Cp*Ru(,-Cl)3ML] [LM = (C6H6)Ru, (cymene)Ru, (1,3,5-C6H3iPr3)Ru, Cp*Rh, Cp*Ir] were prepared by reaction of [Cp*Ru(,-OMe)]2 with Me3SiCl and subsequent addition of [LMCl2]2. The complexes [Cp*Ru(,-Cl)3Ru(cymene)] and [Cp*Ru(,-Cl)3IrCp*] were characterized by single-crystal X-ray analyses. In crossover experiments with [Cp*Rh(,-Cl)3RuCl(PPh3)2] and [Cp*Ru(,-Cl)3Ru(1,3,5-C6H3iPr3)] in CD2Cl2, a dynamic equilibrium with the complexes [Cp*Rh(,-Cl)3RuCp*] and [(1,3,5-C6H3iPr3)Ru(,-Cl)3RuCl(PPh3)2] was rapidly established, demonstrating the kinetic lability of the triple chloro bridge. Upon reaction of [Cp*Rh(,-Cl)3RuCp*] with benzene, the ionic complex [Cp*Ru(C6H6)][Cp*RhCl3] was formed, which was characterized by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] | ||||||||||