Validated high-performance liquid chromatographic assay for the determination of promazine in human plasma. Application to pharmacokinetic studies

A high-performance liquid chromatographic method for the determination of promazine in human plasma is described. The assay involves a single-step liquid-liquid extraction using pentane-2-propanol (98:2, v/v). The analyte of interest and the internal standard chlorpromazine were separated on a Spherisorb CN column using a mobile phase of acetonitrile-50 mM ammonium acetate (9:1, v/v). Electrochemical detection was achieved using an applied potential of +750 mV. The assay was validated according to international requirements prior to application to a pharmacokinetic study and was found to be specific, accurate and precise with a linear range of 0.25-25 ng ml(-1).     

Late lateralizing and localizing EEG features of scalp-recorded temporal lobe seizures

The fungicidal properties of the synthetic peptide D4E1 were studied with nongerminated and germinating conidia of Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium moniliforme, and Fusarium oxysporum. The minimal lethal concentrations (MLC) needed to kill 100% of germinating conidia of A. fumigatus, A. flavus, and A. niger were 12.5, 12.5, and 25 microM, respectively. The MLC value for nongerminated and germinating conidia of both Fusarium spp. was 3.0 microM. Except for A. fumigatus, D4E1 was inactive against the nongerminated conidia of the Aspergillus spp. Physicochemical studies showed D4E1 complexed with ergosterol, a sterol present in conidial walls. Cholesterol, present in nongerminated conidia of F. moniliforme, had a greater affinity for D4E1 than did ergosterol. D4E1 was more resistant to fungal and plant protease degradation than the natural peptide, cecropin A. These in vitro results suggest D4E1 is a candidate for transgenic expression in plants to enhance host resistance to fungal infection.     

Effect of high-temperature processing on the creation of boron-related deep levels in 4H-SiC

High-temperature processing was applied to SiC boron-doped epitaxial layers, epitaxial layers grown on boron-rich substrates, and boron-implanted samples in order to establish conditions favorable for the formation of boron-related centers (D-centers) that introduce a deep level in SiC bandgap. Photoluminescence (PL) was used to detect and compare the formation of the D-center after different processing steps. It was confirmed that the presence of lattice defects was required for achieving significant boron diffusion and D-center formation. In addition, epitaxial growth on the top of a boron-implanted sample yielded efficient boron in-diffusion in the growing layer, which resulted in a material compensated with D-centers. The temperature dependence of the D-center formation efficiency was investigated.     

Relative bioavailability of paracetamol in suppositories preparations in comparison to tablets

Relative Bioavailability of Paracetamol as Suppositories Compared to Tablets. The relative bioavailability of paracetamol (CAS 103-90-2) in ben-u-ron 500 mg and ben-u-ron 1000 mg suppositories (test formulations) was compared with that of Benuron tablets 500 mg (reference product) in an open, intraindividual, 3-period-changeover-study in 18 healthy subjects. Plasma concentrations of paracetamol were determined using a specific and sensitive HPLC method with UV detection. For the assessment of bioavailability AUC, Cmax, tmax and HVD were used as pharmacokinetic characteristics. Bioequivalence of the rectal formulations was tested by calculating 90% confidence intervals using the Two-one-sided-t-tests-procedure and log-transformed data of AUC and Cmax. For AUC the confidence intervals were required to be in the 80 and 125% range, for Cmax between 70 and 143% (inclusion rule). Data from 17 subjects could be evaluated. Bioavailability of paracetamol was 89 and 90% for the 500 and 1000 mg suppositories, respectively compared with that of the 500 mg reference tablets. Mean maximum paracetamol plasma concentrations (Cmax) were 3.55 and 6.02 or 7.16 mg/l after administration of the 500 and 1000 mg suppositories or the 500 mg tablets, respectively. These maximum concentrations were achieved 2.0, 2.7 and 0.6 h (tmax) after administration of the respective preparations. The corresponding HVD values were 4.3, 5.2 and 2.0 h, respectively. After dose adjustment of the results for the 1000 mg suppositories relative bioavailabilities of paracetamol from both rectal formulations exceeded 80% of that from the tablets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Divalent transition metal cations counteract potassium-induced quadruplex assembly of oligo(dG) sequences

Nucleic acids containing tracts of contiguous guanines tend to self-associate into four-stranded (quadruplex) structures, based on reciprocal non-Watson-Crick (G*G*G*G) hydrogen bonds. The quadruplex structure is induced/stabilized by monovalent cations, particularly potassium. Using circular dichroism, we have determined that the induction/stabilization of quadruplex structure by K+is specifically counteracted by low concentrations of Mn2+(4-10 mM), Co2+(0.3-2 mM) or Ni2+(0.3-0.8 mM). G-Tract-containing single strands are also capable of sequence-specific non-Watson-Crick interaction with d(G. C)-tract-containing (target) sequences within double-stranded DNA. The assembly of these G*G.C-based triple helical structures is supported by magnesium, but is potently inhibited by potassium due to sequestration of the G-tract single strand into quadruplex structure. We have used DNase I protection assays to demonstrate that competition between quadruplex self-association and triplex assembly is altered in the presence of Mn2+, Co2+or Ni2+. By specifically counteracting the induction/stabilization of quadruplex structure by potassium, these divalent transition metal cations allow triplex formation in the presence of K+and shift the position of equilibrium so that a very high proportion of triplex target sites are bound. Thus, variation of the cation environment can differentially promote the assembly of multistranded nucleic acid structural alternatives.     

Embedding of Dedicated High-Performance ASICs into Reconfigurable Systems Providing Additional Multimedia Functionality

The computational power required in many multimedia applications is well beyond the capabilities of today's multimedia systems. Therefore, the embedding of additional high-performance accelerator multimedia components into these systems is most decisive. This paper presents the embedding of multimedia components into computer systems using reconfigurable coprocessor boards. The goal of those reconfigurable platforms which can be adapted to several applications and which include programmable digital signal processors, control and memory devices as well as dedicated multimedia ASICs is worked out. On the way to such a platform four ASICs for image and text processing are presented. The embedding of these components into a computing system using a CardBus-based coprocessor board is shown. Such a reconfigurable coprocessor board is an important intermediate stage on the way to future hybrid reconfigurable systems on chip.     

Internet-enabled modelling of extended manufacturing enterprises using process-based techniques

This article presents the preliminary results of an ongoing research project on Internet-enabled process-based modelling of extended manufacturing enterprises. We propose applying the open system architecture for CIM (CIMOSA) modelling framework alongside object-oriented Petri net models of enterprise processes and object-oriented techniques for extended enterprises modelling. We describe the main features of the proposed approach and discuss some components. We present elementary examples of object-oriented Petri net implementation and real-time visualisation.