The nitrosocarbonyl hetero-Diels-Alder reaction as a useful tool for organic syntheses

Organic transformations that result in the formation of multiple covalent bonds within the same reaction are some of the most powerful tools in synthetic organic chemistry. Nitrosocarbonyl hetero-Diels-Alder (HDA) reactions allow for the simultaneous stereospecific introduction of carbon-nitrogen and carbon-oxygen bonds in one synthetic step, and provide direct access to 3,6-dihydro-1,2-oxazines. This Review describes the development of the nitrosocarbonyl HDA reaction and the utility of the resulting oxazine ring in the synthesis of a variety of important, biologically active molecules.     

Organometallic reactions of α-haloimines as a useful tool in organic synthesis

The reaction of organometallic reagents, e.g. alkyllithiums, cuprates and alkylcoppers, with α-haloimines gave selectively a variety of synthetically useful reactions, including coupling to 1,4-diimines, homologation, and production of heterocycles.     

Biosensors as useful tools for environmental analysis and monitoring

Recent advances in the development and application of biosensors for environmental analysis and monitoring are reviewed in this article. Several examples of biosensors developed for relevant environmental pollutants and parameters are briefly overviewed. Special attention is paid to the application of biosensors to real environmental samples, taking into consideration aspects such as sample pretreatment, matrix effects and validation of biosensor measurements. Current trends in biosensor development are also considered and commented on in this work. In this context, nanotechnology, miniaturisation, multi-sensor array development and, especially, biotechnology arise as fast-growing areas that will have a marked influence on the development of new biosensing strategies in the near future.     

The oxime bond formation as a useful tool for the preparation of oligonucleotide conjugates

Synthetic oligonucleotides are attracting considerable interest as potential therapeutic agents for the selective inhibition of gene expression. The attainment of effective cellular delivery however remains a problem. The conjugation of oligonucleotides to cell penetrating peptides is one of the most promising alternatives, that is being currently investigated to improve the uptake efficiency of oligonucleotides. The synthesis of peptide–oligonucleotide conjugates (POC) is however still a problem. Work from our laboratory has attempted to address the problem of POC synthesis by using the chemoselective oxime bond formation. Herein, we present an account of the work accomplished in our laboratory in the recent past, concerning the conjugation of various reporters to oligonucleotides. To cite this article: Y. Singh et al., C. R. Chimie 8 (2005).     

Selected Imidazolium Ionic Liquids as a Terminating Electrolyte in Isotachophoresis

Results of application of selected imidazolium ionic liquids [especially EMIM (1-ethyl-3-methyl-imidazolium) cation] as a new type of terminating electrolyte (TE) in isotachophoresis (ITP) with conductometric detection are presented. In experiments seven different types of leading electrolyte (LE) with new terminating electrolyte were studied. After selection of parameters influenced on the analysis resolution, buffers were successfully used in control of qualitative and quantitative analysis (sodium, potassium, calcium, and magnesium) of different type of waters. The new ITP method was satisfying and basic validation parameters were assigned.     

Flow injection microscopy as a tool for two-parameter monitoring of cellular responses

Flow Injection Fluorescence Microscopy (FIFM) has been further developed to become a useful tool for a multiparametric study of the response of living cells to a biochemical stimulus. Rather than recording several parameters simultaneously, the multiparametric measurements are carried out in a sequential fashion: internal Ca-concentration and pH of Chinese Hamster Ovary cells were alternately monitored in subsequent runs where the cells were exposed to carbachol. Delivery of carbachol onto the cells was carried out by the flow injection apparatus in the FIFM setup. Fluorescent indicators fura-2 and BCECF had been loaded into the cells to provide the Ca- and pH dependent signals, respectively. The fluorescent signals were detected by means of the fluorescent microscope domain of the FIFM setup. Comparison of the temporal dependence of the response curves shows differences in the two responses. The experimental evidence is supported by a novel functional tracer test that is used to characterize the kinetics of cell-stimulation interaction. Received: 15 December 1997 / Revised: 25 March 1998 / Accepted: 1 April 1998     

Flow injection microscopy as a tool for two-parameter monitoring of cellular responses

Flow Injection Fluorescence Microscopy (FIFM) has been further developed to become a useful tool for a multiparametric study of the response of living cells to a biochemical stimulus. Rather than recording several parameters simultaneously, the multiparametric measurements are carried out in a sequential fashion: internal Ca-concentration and pH of Chinese Hamster Ovary cells were alternately monitored in subsequent runs where the cells were exposed to carbachol. Delivery of carbachol onto the cells was carried out by the flow injection apparatus in the FIFM setup. Fluorescent indicators fura-2 and BCECF had been loaded into the cells to provide the Ca- and pH dependent signals, respectively. The fluorescent signals were detected by means of the fluorescent microscope domain of the FIFM setup. Comparison of the temporal dependence of the response curves shows differences in the two responses. The experimental evidence is supported by a novel functional tracer test that is used to characterize the kinetics of cell-stimulation interaction. Received: 15 December 1997 / Revised: 25 March 1998 / Accepted: 1 April 1998     

A practicable two-dimensional electrophoresis of urinary proteins as a useful tool in medical diagnosis

Practical experience with a rapid two-dimensional electrophoresis technique for routine analysis of urinary proteins is discussed. The method consists of cellulose acetate electrophoresis in combination with sodium dodecyl sulfate (SDS) electrophoresis, performed together with Coomassie Blue gel staining on "PhastSystem". Over 400 analyses were performed within the time of two years. Most patients were from nephrological, urological and kidney-transplant departments. Some of them were from obstetric, pediatric or oncological departments. A systematic discussion and evaluation of the two-dimensional protein pattern with typical examples is outlined.     

Electrochemistry as a tool for nano-TiO2 deposition and for photoremediation pollutant monitoring

In the present work electrochemical technologies are used i) to obtain nanotitania films, by electrophoretic deposition from a slurry of commercial TiO₂ in acetylacetone and ii) to monitor in situ the photodegradation of a model organic molecule (formic acid) in water, by using the same electrodeposited layers, which permit the elimination of filtration steps.     

Internal user inquiries as a useful tool for adjustment of the quality system and for quality improvement

Who could be better than the staff themselves to point out inappropriate and ineffective elements in a quality system? A dialogue between the supplier and the customer for clarification of the customers' requirements and possible quality problems is often part of a quality management system. Of no less importance is a dialogue with the staff who "live" with the quality system in the everyday work environment, handling procedures, keeping records, and controlling documents, etc. For this reason a simple internal user inquiry was conducted. The anonymous inquiry form considered areas which effect daily work, and posed questions which, we had reasons to believe, could be tender points among staff. The result was a very positive feedback on the questions, and several advantages and disadvantages were brought forward. Our experience after 2 years with ISO 9001 certification is that internal inquiries are just as important as the dialogue with customers in maintaining an appropriate and effective quality system. Furthermore, such inquiries focus on the quality system and involve the staff in adjustments, tailoring the system and in quality improvements.     

Polyphenolic profile as a useful tool to identify the wood used in wine aging

Although oak wood is the main material used in cooperage, other species are being considered as possible sources of wood for the production of wines and their derived products. In this work we have compared the phenolic composition of acacia (Robinia pseudoacacia), chestnut (Castanea sativa), cherry (Prunus avium) and ash (Fraxinus excelsior and F. americana) heartwoods, by using HPLC-DAD/ESI-MS/MS (some of these data have been showed in previous paper), as well as the changes that toasting intensity at cooperage produce in each polyphenolic profile. Before toasting, each wood shows a different and specific polyphenolic profile, with both qualitative and quantitative differences among them. Toasting notably changed these profiles, in general, proportionally to toasting intensity and led to a minor differentiation among species in toasted woods, although we also found phenolic markers in toasted woods. Thus, methyl syringate, benzoic acid, methyl vanillate, p-hydroxybenzoic acid, 3,4,5-trimethylphenol and p-coumaric acid, condensed tannins of the procyanidin type, and the flavonoids naringenin, aromadendrin, isosakuranetin and taxifolin will be a good tool to identify cherry wood. In acacia wood the chemical markers will be the aldehydes gallic and β-resorcylic and two not fully identified hydroxycinnamic compounds, condensed tannins of the prorobinetin type, and when using untoasted wood, dihydrorobinetin, and in toasted acacia wood, robinetin. In untoasted ash wood, the presence of secoiridoids, phenylethanoid glycosides, or di and oligolignols will be a good tool, especially oleuropein, ligstroside and olivil, together verbascoside and isoverbascoside in F. excelsior, and oleoside in F. americana. In toasted ash wood, tyrosol, syringaresinol, cyclolovil, verbascoside and olivil, could be used to identify the botanical origin. In addition, in ash wood, seasoned and toasted, neither hydrolysable nor condensed tannins were detected. Lastly, in chestnut wood, gallic and ellagic acids and hydrolysable tannins of both the gallotannin and ellagitannin type, can be used as chemical markers.     

Passive sampling as a tool for obtaining reliable analytical information in environmental quality monitoring

Passive sampling technology has been developing very quickly for the past 20 years, and is widely used for monitoring pollutants in different environments, for example air, water, and soil. It has many significant advantages, including simplicity, low cost, no need for expensive and complicated equipment, no power requirements, unattended operation, and the ability to produce accurate results. The present generation of passive samplers enables detection and analysis of bioavailable pollutants at low and very low concentrations and investigation of the environmental concentration of organic and inorganic pollutants not only on the local scale but also on continental and global scales. This review describes the current application of passive sampling techniques in environmental analysis and monitoring, under both equilibrium and non-equilibrium conditions.     

Immunodetection of lactosylated proteins as a useful tool to determine heat treatment in milk samples

This paper reports the optimisation of a competitive immunoassay (ELISA) to detect lactosylated proteins in milk samples. The assay employs monoclonal antibodies for lactosylated proteins produced in our laboratory and requires no pre-treatment of the samples other than a dilution step. Monoclonal antibodies were fully characterised in terms of selectivity and cross-reactivity with structurally related molecules and used in a competitive assay format with lactosylated standard proteins (lactosylated ovalbumin). The detection limit for lactosylated ovalbumin was 0.015 microgram ml-1 and the working range was from 0.010 to 40 micrograms ml-1. The data obtained indicate that the ELISA developed is applicable to diluted milk samples and is able to distinguish between milk samples that have undergone different heat treatments (UHT and pasteurised milk).     

Polarimetry as a useful tool for the determination of binding constants between cyclodextrins and organic guest molecules

Binding constants for cyclodextrin inclusion complexes can be easily estimated by means of simple polarimetric measurements. Determinations are as reliable and accurate as those obtained by means of other more sophisticated techniques, and take advantage by the limited waste of material required. Our results are briefly compared with literature values obtained by means of different techniques.     

95Mo NMR: a useful tool for structural studies in solution

Oxomolybdenum(VI) complexes containing diverse ligands from an electronic and topological point of view have been analysed by means of ⁹⁵Mo NMR in solution with the purpose of using this technique as a tool to study their coordination chemistry and reactivity. The relationship between the electronic density on the metal tuned by the electron‐donor ability of the coordinated ligands and the ⁹⁵Mo chemical shift has been proved for mono‐ and bimetallic complexes showing a hexa‐ or hepta‐coordination around the metal centre. The different origins of the signal broadening (associated either to the symmetry of the metallic polyhedron or to the presence of isomers or to the ligand de‐coordination) have been also considered to rationalise the obtained data. Copyright © 2009 John Wiley & Sons, Ltd.     

Sheathless CE-MS as a tool for monitoring exchange efficiency and stability of bispecific antibodies

Bispecific monoclonal antibodies (BsAbs) are receiving great attention due to their extensive benefits as biopharmaceuticals and their involvement in IgG4 mediated autoimmune diseases. While the production of BsAbs is getting more accessible, their analytical characterization remains challenging. We explored the potential of sheathless CE-MS for monitoring exchange efficiency and stability of in-house produced bispecific antibodies. Two IgG4 bispecific antibodies with different molecular characteristics were prepared using controlled Fragment antigen binding (Fab)-arm exchange. Separation of BsAbs from their parent monospecific antibodies was achieved using a polyethyleniimine (PEI)-coated capillary and acidic background electrolytes permitting reliable assessment of the exchange efficiency. This was especially valuable for a Fab-glycosylated BsAb where the high glycan heterogeneity resulted in an overlap of masses with the monospecific parent antibody, hindering their discrimination by MS only. The method showed also good capabilities to monitor the stability of the generated BsAbs under different storage conditions. The levels of degradation products were different for the studied antibodies indicating pronounced differences in stability. Overall, the proposed method represents a useful analytical tool for exchange efficiency and stability studies of bispecific antibodies.     

Analysis of gene expression as a new tool in ecotoxicology and environmental monitoring

Pollution affects biological mechanisms in exposed biota, with adverse effects on tissue, organism and, eventually, entire ecosystem levels. Ecotoxicological biomarkers reflect these pollutant-induced physiological alterations, usually by measuring changes in the activity of specific enzymes, or alterations in hormone or protein levels. New, robust polymerase-chain-reaction (PCR)-based methodologies for quantifying specific messenger-RNA molecules have allowed the development of a new family of biomarkers based on analysis of gene-expression patterns. These gene-expression biomarkers have already been applied to many aspects of risk assessment, from toxicological analyses of new substances to in-field monitoring schemes. We review the fundamentals of these techniques, their application in different environmental surveys, their limitations and the outlook for their use in the future.     

Oxazoline as a useful tool in organic synthesis: preparation of 4-aryl-1,2,3,4-tetrahydroisoquinoline alkaloid skeleton

New direct strategy for the synthesis of 4-aryl-1,2,3,4-tetrahydroisoquinolines. The key steps are based on oxazoline chemistry: nucleophilic substitution in an ortho-methoxyphenyloxazoline with a Grignard reagent and a 1,6-conjugate addition of a lithium amide to o-styrylphenyloxazoline.     

Pyrolysis-gas chromatography/mass spectrometry analysis as a useful tool in forensic examination of automotive paint traces

Pyrolysis (Py)-GC/MS was applied in comparative analysis of polymer binder of 150 automobile clearcoat samples. It was found that binders of identical type and similar infrared spectra can be, in most cases, effectively differentiated, sometimes based only on the presence of peaks of very low intensity originating from minor paint components. The qualitative procedure of pyrograms comparison was developed. The results obtained, enable one to draw the conclusion that Py-GC/MS appears as valuable, very informative analytical technique of car paint samples examination. Providing identification of paint pyrolysis products, it enables discrimination of samples on the basis of their composition. However, in some cases, paint samples were still indistinguishable on the basis of their pyrograms.