1,674 research outputs found
Medicinal Chemistry: A Teacher's and Worker's Perspective
This personal commentary aims at offering a description of the origin, purpose, and methods of medicinal chemistry, and a delineation of its fields of activity in connection with related sciences. Directions of future development of medicinal chemistry as a science are suggested
The quenched generating functional for hadronic weak interactions
The ultraviolet behaviour of the generating functional for hadronic weak
interactions with is investigated to one loop for a generic
number of flavours and in the quenched approximation. New quenched chiral
logarithms generated by the weak interactions can be accounted for via a
redefinition of the weak mass term in the weak effective
Lagrangian at leading order. Finally, we illustrate how chiral logarithms are
modified by the quenched approximation in matrix elements with
and 3/2.Comment: LATTICE98(matrixelement), 3 page
A 0-dimensional counter-example to rooting?
We provide an example of a 0-dimensional field theory where rooting does not
work.Comment: 3 pages; Physics Letters B (2010
Results from a Non-Perturbative Renormalization of Lattice Operators
We propose a general renormalization method, which avoids completely the use
of lattice perturbation theory. We present the results from its numerical
applications to two-fermion operators on a lattice, at
.Comment: 3 pages postscript file. Contribution to Lattice '9
Non-Perturbative Renormalisation and Kaon Physics
A general review is presented on the problem of non perturbative computation
of the transition amplitude.Comment: 8 pages, Latex, uses espcrc2.sty, Talk given at LATTICE9
Non-perturbative renormalization in kaon decays
We discuss the application of the MPSTV non-perturbative method \cite{NPM} to
the operators relevant to kaon decays. This enables us to reappraise the
long-standing question of the rule, which involves
power-divergent subtractions that cannot be evaluated in perturbation theory.
We also study the mixing with dimension-six operators and discuss its
implications to the chiral behaviour of the parameter.Comment: Talk presented at LATTICE96(improvement), LaTeX 3 pages, uses
espcrc2, 2 postscript figure
Quantitative Structure-Permeation Relationships (QSPeRs) to Predict Skin Permeation: A Critical Evaluation
Purpose. Development of reliable mathematical models to predict skin permeability remains a challenging objective. This article examines some of the existing algorithms and critically evaluates their statistical relevance. Methods. Complete statistics were recalculated for a number of published models using a stepwise multiple regression procedure. The predictivity of the models was obtained by cross-validation using a "leave-one-out” deletion pattern. The relative contribution of each independent variable to the models was calculated by a standardization procedure. Results. The heterogeneity of the data in terms of skin origin and experimental conditions has been shown to contribute to the residual variance in existing models. Furthermore, rigorous statistics demonstrate that some published models are based on nonsignificant parameters. As such, they afford misleading mechanistic insight and will lead to over-interpretation of the data. Conclusions. The large number of published models reflects the need for predictive tools in cutaneous drug delivery and toxicology. However, such models are more reliable when confined within well-defined chemical classes, and their applicability is often limited by the narrow property space of the set of permeants under stud
The bioavailability of bromazepam, omeprazole and paracetamol given by nasogastric feeding tube
Aims: To characterize and compare the pharmacokinetic profiles of bromazepam, omeprazole and paracetamol when administered by the oral and nasogastric routes to the same healthy cohort of volunteers. Methods: In a prospective, monocentric, randomized crossover study, eight healthy volunteers received the three drugs by the oral (OR) and nasogastric routes (NT). Sequential plasma samples were analyzed by high-performance liquid chromatography-UV, pharmacokinetic parameters (Cmax, , t½, ke, tmax) were compared statistically, and Cmax, and tmax were analyzed for bioequivalence. Results: A statistically significant difference was seen in the of bromazepam, with nasogastric administration decreasing availability by about 25%: AUCOR = 2501 ng mL−1 h; AUCNT = 1855ng mL−1 h (p 0.05); ratio (geometric mean) = 1.01 (90% CI 0.64-1.61). An extended study with a larger number of subjects may possibly provide clearer answers. The narrow 90% confidence limits of paracetamol indicate bioequivalence: AUCOR = 37μg mL−1 h; AUCNT = 41μg mL−1 h(p > 0.05); ratio (geometric mean) = 1.12 (90% CI 0.98-1.28). Conclusion: The results of this study show that the nasogastric route of administration does not appear to cause marked, clinically unsuitable alterations in the bioavailability of the tested drug
Development of an in Vitro Rat Intestine Segmental Perfusion Model to Investigate Permeability and Predict Oral Fraction Absorbed
Purpose: The aims of the study are to develop and evaluate an in vitro rat intestine segmental perfusion model for the prediction of the oral fraction absorbed of compounds and to assess the ability of the model to study intestinal metabolism. Methods: The system consisted of a perfusion cell with a rat intestinal segment and three perfusion circulations (donor, receiver, and rinsing circulation). Lucifer yellow (LY) was applied as internal standard together with test compounds in the donor circulation. To validate the model, the permeability of eight noncongeneric passively absorbed drugs was determined. Intestinal N-demethylation of verapamil into norverapamil was followed in the donor and receiver circulations by high-performance liquid chromatography analysis. Results: The in vitro model allowed ranking of the tested compounds according to their in vivo absorption potential. The Spearman's correlation coefficient between the oral fraction absorbed in humans and the ratio of permeation coefficient of test compound to the permeation coefficient of LY within the same experiment was 0.98 (P < 0.01). Moreover, intestinal N-demethylation of verapamil, its permeation, and the permeation of its metabolite norverapamil could be assessed in parallel. Conclusions: Up to six permeation kinetics can be obtained per rat, and the method has shown to be a valuable tool to estimate human oral absorptio
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