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Rapid Phase (rapid + phase)
Selected AbstractsThe use of simple dynamic mucosal models and confocal microscopy for the evaluation of lyophilised nasal formulationsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2007Fiona McInnes A range of methods is reported in the literature for assessing hydration and adhesion parameters in the performance of nasal bioadhesive formulations; however, these tests do not always represent the dynamic conditions in the nasal cavity. Lyophilised formulations intended for nasal administration were evaluated using in-vitro tests designed in an attempt to mimic relevant processes in the nasal cavity, and intended to discriminate between different formulations. Initial investigative studies using scanning electron microscopy revealed that the lyophilisate had a highly porous internal structure, expected to provide an ideal porous pathway for re-hydration. Vapour sorption analysis demonstrated substantial weight gain of the lyophilisates on exposure to 95% relative humidity, ranging from 38% to 66%. Agar was used as a synthetic mucosal model designed to provide a standardised quantity of water available for rehydration of the formulations in in-vitro tests. A dynamic adhesion test and a texture analyser sliding test were designed to quantify different aspects of the spreading and adhesion of the hydrating formulations on the synthetic mucosal surface. Examination of the lyophilised formulations using confocal microscopy allowed visualisation and quantification of the initial rate of water ingress into the lyophilisates, which was found to consist of an initial rapid phase, followed by a slower steady-state phase. The results demonstrated that the use of a combination of methods representing the dynamic conditions of the nasal cavity is advisable in order to evaluate a formulation fully and to avoid misleading conclusions. [source] Dose,response feeding study of short chain chlorinated paraffins (SCCPs) in laying hens: Effects on laying performance and tissue distribution, accumulation and elimination kineticsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 2 2007Karl-Heinz Ueberschär Abstract Technical short chain chlorinated paraffins (C10,C13 with 60% chlorine) were fed to 93 laying hens from 24 to 32 weeks of age in increasing concentrations of up to 100 mg/kg feed. No significant influence on health, relative organ weights or performance (laying intensity, egg weight, feed consumption) was noted. The chlorinated paraffin content of the tissues was linearly related to the concentration of short chain paraffins of the feed. The highest concentrations were found in abdominal fat, egg yolk and fatty tissues. Breast muscle, egg albumen and bile fluid contained minimal or no residues. Less than 1% of the chlorinated paraffins ingested were incorporated into the body (without head, feet, gut and feathers), whereas about 1.5% were eliminated with the egg yolk and 30% were excreted with urine and faeces. A six-week kinetic depuration study revealed a biphasic elimination with half-lifes of 4,40 min (liver, kidneys, legs, fat, blood) for the initial rapid phase, and 15,30 days (blood, fat, liver, yolk, kidneys, legs) for the terminal slow phase. [source] The sodium-calcium exchanger is a mechanosensitive transporterTHE JOURNAL OF PHYSIOLOGY, Issue 6 2008John P. Reeves This report describes the influence of fluid flow and osmotically induced volume changes on Na+,Ca2+ exchange (NCX) activity in transfected CHO cells. Exchange activity was measured as Na+ -dependent Ca2+ or Ba2+ fluxes using the fluorescent probe fura-2. When exchange activity was initiated by superfusing Ba2+ -containing solutions over the cells for a 20 s interval, a high rate of Ba2+ uptake was observed while the solution was being applied but the rate of Ba2+ uptake declined > 10-fold when the solution flow ceased. Ba2+ efflux in exchange for extracellular Na+ or Ca2+ (Ba2+,Ca2+ exchange) was similarly biphasic. During NCX-mediated Ca2+ uptake, a rapid increase in cytosolic [Ca2+] to a peak value occurred, followed by a decline in [Ca2+]i to a lower steady-state value after solution flow ceased. When NCX activity was initiated by an alternate procedure that minimized the duration of solution flow, the rapid phase of Ba2+ influx was greatly reduced in magnitude and Ca2+ uptake became nearly monophasic. Solution superfusion did not produce any obvious changes in cell shape or volume. NCX-mediated Ba2+ and Ca2+ influx were also sensitive to osmotically induced changes in cell volume. NCX activity was stimulated in hypotonic media and inhibited in hypertonic media; the osmotically induced changes in activity occurred within seconds and were rapidly reversible. We conclude that NCX activity is modulated by both solution flow and osmotically induced volume changes. [source] Magnetic survey of emission line B-type stars with FORS 1 at the VLT,ASTRONOMISCHE NACHRICHTEN, Issue 7 2009S. Hubrig Abstract We report the results of our search for magnetic fields in a sample of 16 field Be stars, the binary emission-line B-type star , Sgr, and in a sample of fourteen members of the open young cluster NGC3766 in the Carina spiral arm. The sample of cluster members includes Be stars, normal B-type stars and He-strong/He-weak stars. Nine Be stars have been studied with magnetic field time series obtained over ,1 hour to get an insight into the temporal behaviour and the correlation of magnetic field properties with dynamical phenomena taking place in Be star atmospheres. The spectropolarimetric data were obtained at the European Southern Observatory with the multi-mode instrument FORS1 installed at the 8m Kueyen telescope. We detect weak photospheric magnetic fields in four field Be stars, HD 62367, , Cen, o Aqr, and , Tuc. The strongest longitudinal magnetic field, ,Bz, = 117 ± 38 G, was detected in the Be star HD 62367. Among the Be stars studied with time series, one Be star, , Eri, displays cyclic variability of the magnetic field with a period of 21.12 min. The binary star , Sgr, in the initial rapid phase of mass exchange between the two components with strong emission lines in the visible spectrum, is a magnetic variable star, probably on a timescale of a few months. The maximum longitudinal magnetic field ,Bz, = ,102 ± 10 G at MJD 54333.018 was measured using hydrogen lines. The cluster NGC3766 seems to be extremely interesting, where we find evidence for the presence of a magnetic field in seven early B-type stars out of the observed fourteen cluster members (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Evidence for weak magnetic fields in early-type emission starsASTRONOMISCHE NACHRICHTEN, Issue 10 2007S. Hubrig Abstract We report the results of our study of magnetic fields in a sample of 15 Be stars using spectropolarimetric data obtained at the European Southern Observatory with the multi-mode instrument FORS 1 installed at the 8m Kueyen telescope. We detect weak photospheric magnetic fields in four stars, HD56014, HD148184, HD155806, and HD181615. We note that for HD181615 the evolutionary status is not obvious due to the fact that it is a binary system currently observed in the initial rapid phase of mass exchange between the two components. Further, we notify the possible presence of distinct circular polarisation features in the circumstellar components of Ca II H&K in three stars, HD58011, HD117357, and HD181615, hinting at a probable presence of magnetic fields in the circumstellar mass loss disks of these stars. We emphasize the need for future spectropolarimetric observations of Be stars with detected magnetic fields to study the temporal evolution of their magnetic fields and the correlation of magnetic field properties with dynamical phenomena taking place in the gaseous circumstellar disks of these stars. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Differential effects of drugs interacting with autonomic transmitters on responses of rat vas deferens to field stimulationAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 2 2000C. Boselli 1 Frequency,response curves (0.1,30 Hz) were obtained in the epididymal portion of rat vas deferens. At low frequencies (0.1,1 Hz), the parameters evaluated were the first twitch and the fourth twitch at each frequency. The responses to trains of stimuli at intermediate (2,5 Hz) and high (10,30 Hz) frequencies were biphasic consisting of phase I (the first rapid phase of tetanus) and of phase II (the secondary slowly developing one). 2 Prazosin inhibited the first and the fourth twitch but not when the frequency was <1 Hz. Suramin inhibited the first twitch while substantially depressing the fourth one. The combination of prazosin and suramin almost completely abolished all the twitches evoked by a train of stimuli at low frequencies. Nifedipine left almost unaltered the first twitch while markedly depressing the fourth one, especially at relatively high frequency (1 Hz). Verapamil was devoid of any inhibitory action. Papaverine depressed the first twitch while only at the highest concentration used (1×10,4 m) markedly inhibited the fourth one. Chloroethylclonidine (CEC) depressed the first twitch and increased the fourth. 3 When intermediate (2,5 Hz) and high (10,30 Hz) frequencies are considered, prazosin and suramin partially inhibited both phase I and phase II, while in combination they almost completely abolished both phases. Nifedipine and verapamil selectively suppressed phase II, leaving phase I unaffected. Papaverine completely abolished both phase I and phase II. CEC was able to completely abolish phase I but increased phase II. 4 These results suggest that the response to the first twitch of a train at low frequency is prevailingly noradrenergic, prazosin-sensitive, while when the twitches are close enough (i.e. at 1 Hz) a summation of stimuli takes place and a predominant purinergic component, both suramin- and nifedipine-sensitive, becomes evident. 5 At high frequencies, both phases are due to the concomitant release of noradrenaline and adenosine triphosphate (ATP). The noradrenergic component of phase I is nifedipine-insensitive and CEC-sensitive, resembling the pharmacological profile of the endogenously released noradrenaline by single pulse, while that of phase II, nifedipine-sensitive and CEC-insensitive, is similar to that produced by exogenously applied noradrenaline. [source] The refolding of type II shikimate kinase from Erwinia chrysanthemi after denaturation in ureaFEBS JOURNAL, Issue 8 2002Eleonora Cerasoli Shikimate kinase was chosen as a convenient representative example of the subclass of ,/, proteins with which to examine the mechanism of protein folding. In this paper we report on the refolding of the enzyme after denaturation in urea. As shown by the changes in secondary and tertiary structure monitored by far UV circular dichroism (CD) and fluorescence, respectively, the enzyme was fully unfolded in 4 m urea. From an analysis of the unfolding curve in terms of the two-state model, the stability of the folded state could be estimated as 17 kJ·mol,1. Approximately 95% of the enzyme activity could be recovered on dilution of the urea from 4 to 0.36 m. The results of spectroscopic studies indicated that refolding occurred in at least four kinetic phases, the slowest of which (k = 0.009 s,1) corresponded with the regain of shikimate binding and of enzyme activity. The two most rapid phases were associated with a substantial increase in the binding of 8-anilino-1-naphthalenesulfonic acid with only modest changes in the far UV CD, indicating that a collapsed intermediate with only partial native secondary structure was formed rapidly. The relevance of the results to the folding of other ,/, domain proteins is discussed. [source] | |||||||||||||