Search results for "preparation"

HPLC study on the ‘history’ dependence of gramicidin A conformation in phospholipid model membranes

1989

AbstractA novel HPLC methodology for the study of gramicidin A reconstituted in model membranes has been tested in comparison with circular dichroism data. It is shown that this chromatographic technique not only corroborates most of the recent spectroscopic results but allows one to explain them in terms of mass fractions of different actual conformational species of GA in the phospholipid assemblies. In particular, the dependence of the inserted peptide configuration on the organic solvent and other parameters involved in the ‘history’ of the sample preparation and handling has been analyzed by HPLC in two phospholipid model systems: small unilamellar vesicles and micelles. Moreover, a sl…

Exploring the binding of Pt drugs to gold nanoparticles for controlled passive release of cisplatin.

2011

Changes in Cerebral Amino Acid Transport During Development

1976

The transport of metabolites to and from the central nervous system is of considerable interest. To a greater extent than most other tissues, central nervous system tissue invitro takes up amino acids to well above their concentrations in the incubation medium. Presumably the transport systems responsible for this uptake and for efflux invitro are also those responsible for transport between brain cells in living animals2.

Strategies to In Vitro Assessment of Major Human CYP Enzyme Activities by Using Liquid Chromatography Tandem Mass Spectrometry

2008

At the early stage of drug discovery, thousands of new chemical entities (NCEs) may be screened before a single candidate can be identified for development. Determining the role of CYP enzymes in the metabolism of a compound and evaluating the effect of NCEs on human CYP activities are key issues in pharmaceutical development as they may explain inter-subject variability, drug-drug interactions, non-linear pharmacokinetics and toxic effects. Reliable methods for determining enzyme activities are needed to characterize an individual CYP enzyme and to obtain a tool for the evaluation of its role in drug metabolism in humans. Different liquid chromatography tandem mass spectrometry methodologi…

The application of phospholipid removal columns and ultra-high performance liquid chromatography-tandem quadrupole mass spectrometry for quantificati…

2016

In this study a robust and sensitive method based on a proposed sample purification procedure, using zirconia-coated Phree™ columns and analysis by ultra-high performance liquid chromatography with triple quadrupole tandem mass spectrometry are presented for the assessment of multi-class antibiotics in farmed fish species. The sample preparation procedure benefited from combined precipitation of proteins and selective removal of phospholipids by Phree™ columns, resulting in a high sensitivity of the method (LOQ 0.3-9mgkg(-1)). The in-house validation results (precision, repeatability, decision limit CCα, detection capability CCβ, etc.) indicate that the elaborated method is fully suitable f…

Preclinical models for colonic absorption, application to controlled release formulation development.

2018

Oral controlled release (CR) formulations have many benefits and have become a valuable resource for the local and systemic administration of drugs. The most important characteristic of these pharmaceutical products is that drug absorption occurs mainly in the colon. Therefore, this review analyses the physiological and physicochemical features that may affect an orally administered CR product, as well as the different strategies to develop a CR dosage form and the methods used to evaluate the formulation efficacy. The models available to study the intestinal permeability and their applicability to colonic permeability determinations are also discussed.

Comparison of the efficacy of chemomechanical caries removal (Carisolv') with that of conventional excavation in reducing the cariogenic flora

2004

Summary.  Objectives.   The usage of minimally invasive procedures and attention to patient comfort are of great importance, especially for dental treatment in small children. This has led to the development of chemomechanical methods for caries removal. The aim of this study was to compare the efficacy of chemomechanical caries removal with that of conventional excavation in reducing the count of the cariogenic flora. Design and setting.  Subjects for this study were chosen from children admitted to dental clinic for restorative procedures under general anaesthesia. Samples and methods.  Twenty-one children (mean age 43·5 ± 12·0 months) with early childhood caries were included in this stu…

Virtual element method for computational homogenization of composite and heterogeneous materials

2020

Abstract In this study, a two-dimensional multi-region framework, based on the use of the Virtual Element Method (VEM), is developed for computational materials homogenization and applied to different classes of widely employed heterogeneous materials. The VEM has recently emerged as a powerful generalisation of the Finite Element Method capable of dealing with very general polygonal mesh elements, including non-convex or highly distorted elements. Such features are appealing for the treatment of problems whose analysis domains present complex or statistical morphological features, which would generally require careful and time-consuming mesh/data preparation and regularization. In this wor…

Continuing Education in the Health Sciences in Spain

2008

<div class="ftSection"><span class="ftInlineSubsectionTitle">Background:</span><p>Employers have long been concerned about the professional qualifications of their employees. Decision makers in the health sciences are no exception, particularly now that they are seriously considering the improvement and full accreditation of continuing education as part of the planned European convergence.</p></div><div class="ftSection"><span class="ftInlineSubsectionTitle">Method:</span><p>Medical and nursing professionals were questioned about their views on continuing education, suitable content of possible programs, and implementation, in comp…

Recommendation of RILEM TC237-SIB on cohesion test of recycled asphalt

2018

This recommendation describes how to evaluate the presence of potentially active bitumen in recycled asphalt (RA) materials through the cohesion test. The experimental protocol is designed according to the research performed by the RILEM Technical Committee 237-SIB ‘‘Testing and characterization of sustainable innovative bituminous materials and systems’’ with the purpose, to develop a new, simple and fast method for the characterization of RA while limiting the need for conventional rheological tests. The guidelines in this recommendation focus on the testing procedure including specimen preparation, data analysis and provide information on the preparation of a tests report.