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System Only (system + only)
Selected AbstractsPharmacological principles of antidepressant efficacyHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue S1 2002Alan F. Schatzberg Abstract Both noradrenaline (NA) and serotonin (5-HT) appear to be involved in depression. Evidence suggests that dual-acting antidepressants, i.e. those that affect both monoamine systems, such as tricyclic antidepressants and the noradrenergic and specific serotonergic antidepressant mirtazapine, may have greater efficacy and a faster onset of action than drugs that act on a single monoamine system only, such as the selective serotonin reuptake inhibitors (SSRIs). Cell firing is reduced by SSRIs in the short-term, but is increased by mirtazapine, probably due to its actions on both NA (via ,2 antagonism) and 5-HT (via ,1 -stimulation by NA). This may help to explain clinical evidence suggesting that mirtazapine has a faster onset of action than the more selective antidepressants. Copyright © 2002 John Wiley & Sons, Ltd. [source] Cost structure of CGAM cogeneration systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2004Ho-Young Kwak Abstract The cost structure of the CGAM system, a predefined cogeneration system suggested to unify the different methodologies of thermoeconomic analysis, was investigated by using a thermoeconomic method called modified productive structure analysis (MOPSA). An emphasis has been specially put on how the cost structure of the system is affected by the chosen level of aggregation that specifies the subsystems. It has been found that the unit cost of products is dependent on the chosen level of aggregation of the system only when one considers the entropy flow as one of the parameters to determine the unit cost of products. Copyright © 2004 John Wiley & Sons, Ltd. [source] The orientation system and migration pattern of long-distance migrants: conflict between model predictions and observed patternsJOURNAL OF AVIAN BIOLOGY, Issue 2 2001Kasper Thorup The requirements of the orientation system of naïve long-distance night migrants were analysed by comparing data on Barred Warbler Sylvia nisoria, Marsh Warbler Acrocephalus palustris and Spotted Flycatcher Muscicapa striata with data from a computer model of a clock-and-compass system. These species show, respectively, a rather restricted winter distribution in East Africa, migration through a very narrow corridor in East Africa, and rather widely distributed recoveries in the Mediterranean with more concentrated recoveries south of the Sahara. For all three species, to obtain the observed concentrations either a very high directional migratory concentration was needed in computer simulations to bring the birds successfully to their wintering areas or misorientating individuals would be subjected to a very high mortality. Neither the very high directional concentration nor the high mortality amongst misorientating individuals fit the empirical data sets. On the basis of the present study, the observed patterns seem difficult to explain by a simple clock-and-compass system only, and to account for the exceptionally precise migratory routes shown in this study it is proposed that first-time migrants might be able to use landscape topography on a regional scale in combination with corrections of directional mistakes/wind displacements. [source] Volume of distribution at steady state for a linear pharmacokinetic system with peripheral eliminationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2004Leonid M. Berezhkovskiy Abstract The problem of finding the steady-state volume of distribution Vss for a linear pharmacokinetic system with peripheral drug elimination is considered. A commonly used equation Vss,=,(D/AUC)*MRT is applicable only for the systems with central (plasma) drug elimination. The following equation, Vss,=,(D/AUC)*MRTint, was obtained, where AUC is the commonly calculated area under the time curve of the total drug concentration in plasma after intravenous (iv) administration of bolus drug dose, D, and MRTint is the intrinsic mean residence time, which is the average time the drug spends in the body (system) after entering the systemic circulation (plasma). The value of MRTint cannot be found from a drug plasma concentration profile after an iv bolus drug input if a peripheral drug exit occurs. The obtained equation does not contain the assumption of an immediate equilibrium of protein and tissue binding in plasma and organs, and thus incorporates the rates of all possible reactions. If drug exits the system only through central compartment (plasma) and there is an instant equilibrium between bound and unbound drug fractions in plasma, then MRTint becomes equal to MRT,=,AUMC/AUC, which is calculated using the time course of the total drug concentration in plasma after an iv bolus injection. Thus, the obtained equation coincides with the traditional one, Vss,=,(D/AUC)*MRT, if the assumptions for validity of this equation are met. Experimental methods for determining the steady-state volume of distribution and MRTint, as well as the problem of determining whether peripheral drug elimination occurs, are considered. The equation for calculation of the tissue,plasma partition coefficient with the account of peripheral elimination is obtained. The difference between traditionally calculated Vss,=,(D/AUC)*MRT and the true value given by (D/AUC)*MRTint is discussed. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:1628,1640, 2004 [source] Stream macroinvertebrate occurrence along gradients in organic pollution and eutrophicationFRESHWATER BIOLOGY, Issue 7 2010NIKOLAI FRIBERG Summary 1.,We analysed a large number of concurrent samples of macroinvertebrate communities and chemical indicators of eutrophication and organic pollution [total-P, total-N, NH4,N, biological oxygen demand (BOD5)] from 594 Danish stream sites. Samples were taken over an 11-year time span as part of the Danish monitoring programme on the aquatic environment. Macroinvertebrate communities were sampled in spring using a standardised kick-sampling procedure whereas chemical variables were sampled six to 24 times per year per site. Habitat variables were assessed once when macroinvertebrates were sampled. 2.,The plecopteran Leuctra showed a significant negative exponential relationship (r2 = 0.90) with BOD5 and occurred at only 16% of the sites with BOD5 above 1.6 mg L,1. Sharp declines with increasing BOD5 levels were found for the trichopteran families Sericostomatidae and Glossosomatidae although they appeared to be slightly less sensitive than Leuctra. Other plecopterans such as Isoperla showed a similar type of response curve to Leuctra (negative exponential) but occurred at sites with relatively high concentrations of BOD5 up to 3,4 mg L,1. In contrast, the response curve of the isopod Asellus aquaticus followed a saturation function reaching a plateau above 3,4 mg L,1 BOD5 and the dipteran Chironomus showed an exponential increase in occurrence with increasing BOD5 concentration. 3.,Macroinvertebrate occurrence appeared to be related primarily to concentrations of BOD5, NH4,N and total-P whereas there were almost no relationships to total-N. Occurrence of a number of taxa showed a stronger relationship to habitat conditions (width and substrate) than chemical variables. 4.,Important macroinvertebrate taxa are reduced at concentrations of BOD5 that are normally perceived as indicating unimpacted stream site conditions. Our results confirmed sensitivity/tolerance patterns used by existing bioassessment systems only to some degree. [source] Note on a Highly Diverse Rotifer Assemblage (Rotifera: Monogononta) in a Laotian Rice Paddy and Adjacent PondINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 6 2007Hendrik Segers Abstract During August 1999, the authors conducted a sampling campaign in the PDR Laos, in order to contribute to the chorology of rotifers in the region. Two samples, collected from a rice paddy and an adjacent pond near Vientiane, Laos, contained a total of 135 rotifer species including several that appear new to science or that warrant taxonomical or biogeographical comments. No new species can be named, but Cephalodella boettgeri Koste and Floscularia armataSegers are recorded for the second time ever after their description from South America, and Parencentrum lutetiae (Harring and Myers) and Polyarthra luminosaKutikova are new to Southeast Asia. This raises the number of rotifers recorded from Laos from 9 to 130. The diversity recorded is remarkable, especially when compared with that of similar habitats in the Thai part of the floodplain of River Mekong and its tributaries. Different agricultural practices may account for the difference in species richness. Similar highly diverse rotifer faunas are known to occur in natural, tropical and subtropical floodplain systems only. This accords with the view that rice paddies can be regarded as artificial wetlands or floodplain systems, which, if managed taking biodiversity concerns into account, may have a potential for the conservation of freshwater biodiversity. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||