Could Polyphenols Really Be a Good Radioprotective Strategy?

Currently, radiotherapy is one of the most effective strategies to treat cancer. However, deleterious toxicity against normal cells indicate for the need to selectively protect them. Reactive oxygen and nitrogen species reinforce ionizing radiation cytotoxicity, and compounds able to scavenge these species or enhance antioxidant enzymes (e.g., superoxide dismutase, catalase, and glutathione peroxidase) should be properly investigated. Antioxidant plant-derived compounds, such as phenols and polyphenols, could represent a valuable alternative to synthetic compounds to be used as radio-protective agents. In fact, their dose-dependent antioxidant/pro-oxidant efficacy could provide a high degree of protection to normal tissues, with little or no protection to tumor cells. The present review provides an update of the current scientific knowledge of polyphenols in pure forms or in plant extracts with good evidence concerning their possible radiomodulating action. Indeed, with few exceptions, to date, the fragmentary data available mostly derive from in vitro studies, which do not find comfort in preclinical and/or clinical studies. On the contrary, when preclinical studies are reported, especially regarding the bioactivity of a plant extract, its chemical composition is not taken into account, avoiding any standardization and compromising data reproducibility.     

Is Cyanide Really a Strong‐Field Ligand?

Iron man or weakling? Ligand‐field strengths are conveniently expressed by the empirical spectrochemical series. Although cyanide has been deeply entrenched as a strong‐field ligand, a couple of recent examples cast doubt toward the position of this ligand, namely the high‐spin (S=2) states of [Cr^II(CN)₅]^3? and [Fe^II(tpp)(CN)]^?. tpp=meso‐tetraphenylporphinate.

     

Characterization of Supercomplex Crude Oil Mixtures: What Is Really in There?

Through different windows : One major obstacle in energy research is the complexity and variety of compounds present in crude oil. A study of different ionization methods for mass spectrometry shows that the mass spectrum very strongly depends on which method is used.

     

Is a molecular orbital measurable by means of tomographic imaging?

Interpretation of experiments involving use of vacuum ultraviolet radiation to effect ionization of N₂ in terms of measurements of a molecular orbital is erroneous.     

Is it safe to have a laboratory test?

A recent US Institute of Medicine report indicated that up to 98,000 deaths and more than 1 million injuries occur each year in the United States due to medical errors. These include diagnostic errors, such as an error or delay in diagnosis, failure to employ indicated tests and the use of outmoded tests. Laboratory tests provide up to 80% of the information used by physicians to make important medical decisions, therefore it is important to determine how often laboratory testing mistakes occur, whether they cause patient harm, where they are most likely to occur in the testing process, and how to prevent them from occurring. A review of the literature and a US Quality Institute Conference in 2003 indicates that errors in laboratory medicine occur most often in the pre-analytical and post-analytical steps in the testing process, but most of the quality improvement efforts focus on improving the analytical process. Measures must be developed and employed to reduce the potential for mistakes in laboratory medicine, including better indicators for the quality of laboratory service. Users of laboratory services must be linked with the laboratorys information system to assist them with decisions about test ordering, patient preparation, and test interpretation. Quality assessment efforts need to be expanded beyond external quality assessment programs to encompass the detection of non-analytical mistakes and improving communication between the users of and providers of laboratory services. The actual number of mistakes in laboratory testing is not fully recognized, because no widespread process is in place to either determine how often mistakes occur or to systematically eliminate sources of error. We also tend to focus on mistakes that result in adverse events, not the near misses that cause no observable harm. The users of laboratory services must become aware of where testing mistakes can occur and actively participate in designing processes to prevent mistakes. Most importantly, healthcare institutions need to adopt a culture of safety, which is implemented at all levels of the organization. This includes establishing closer links between providers of laboratory services and others in the healthcare delivery system. This was the theme of a 2003 Quality Institute Conference aimed at making the laboratory a key partner in patient safety. Plans to create a permanent public–private partnership, called the Institute for Quality in Laboratory Medicine, whose mission is to promote improvements in the use of laboratory tests and laboratory services are underway.Presented at the 9th Conference on Quality in the Spotlight, 18–19 March 2004, Antwerp, Belgium.     

Is it possible to estimate the enantioselectivity of a chiral catalyst from its racemic mixture?

The evaluation of a racemic catalyst was investigated in the case of oxazaborolidine (OAB)-catalyzed borane reduction of 1,5-diphenyl-1,5-pentanedione, giving the corresponding diol. On the basis of the diastereoselectivity of the diols, it is possible to estimate the enantioselectivity (ee) of the first step, which correlates well with the ee in the reaction of the structurally similar phenyl n-pentyl ketone with enantiopure OAB catalyst. The measure of diastereoselectivity could be a tool for screening racemic catalysts without the need for resolving the individual enantiomers, if in the second step of the process there is no substrate control and no catalyst scrambling.     

Cationic polymerization of dienes VIII: Is the elimination of cross-linking by a bulky electron donor a general behavior in the presence of aluminium trichloride?

Previous works on the polymerization of 1,3-pentadiene initiated by aluminium trichloride in non polar solvent at room temperature in the presence of bulky electron donor (ED) as tri-p-tolylamine have highlighted a stabilization of the polymerizing actives centres by ED, which allowed a reduction of some side reactions and the formation of more precisely defined polypentadienes than ever by cationic polymerization in non polar medium. The aim of this research was to investigate the role of bulky EDs such as tri-p-tolylamine and similar compounds in polar medium in order to obtain if possible a complete control of the polymerization of isoprene and 1,3-pentadiene. The beneficial effect of tri-p-tolylamine was shown in the case of isoprene polymerization at room temperature, with an important reduction of the cross-linked fraction for long reaction times and strong reduction of termination reactions. At −30 °C in the presence of tri-p-tolylamine, polypentadienes more controlled than in non polar solvent could be obtained, with a nearly complete elimination of the cross-linked fraction, while keeping the microstructure approximately constant.     

Theoretical study of the semihydrogenation of alkynes catalyzed by Pd(0) complexes: Is a zwitterionic pathway possible?

Density functional theory B3LYP calculations have been carried out for the Pd(diimine)(C₂H₂)+H₂Pd(diimine)(C₂H₄) reaction, which is the key reaction in the semihydrogenation of alkynes homogeneously catalyzed by (diimine)palladium(0) complexes. The results show that a H₂ heterolytic addition across one Pd–N bond opens a feasible zwitterionic pathway for the catalytic process, and accounts for the pairwise transfer of the two hydrogen atoms inferred from parahydrogen induced polarization NMR experiments.Proceedings of the 11th International Congress of Quantum Chemistry satellite meeting in honor of Jean-Louis Rivail     

Analysis of wines by ICP-MS: Is the pattern of the rare earth elements a reliable fingerprint for the provenance?

In a comparative analysis of young and finished product wines by semi-quantitative ICP-MS, a striking difference was observed: finished products exhibited significant concentrations of the rare earth elements whereas the concentrations in young wines which had not been subdued to any treatment after their initial preparation from the grapes were below the determination limits with a quadrupole instrument and could only be determined with a magnetic field instrument operated at a low mass resolution (R = 300). The reason was found in contamination from bentonites as usually applied for the purification of wines from tarnishing components such as proteins. Therefore, bentonites of different origin were extracted with a reference wine, and an increase of the rare earth element concentrations by more than one order of magnitude was observed in the extracts. The investigation leads to the conclusion that the concentration pattern of the rare earth elements can be strongly affected by the wine producing process and therefore is not generally suitable as a fingerprint for the provenance of wines. Received: 3 December 1998 / Revised: 11 February 1999 / Accepted: 18 February 1999     

Analysis of wines by ICP-MS: Is the pattern of the rare earth elements a reliable fingerprint for the provenance?

In a comparative analysis of young and finished product wines by semi-quantitative ICP-MS, a striking difference was observed: finished products exhibited significant concentrations of the rare earth elements whereas the concentrations in young wines which had not been subdued to any treatment after their initial preparation from the grapes were below the determination limits with a quadrupole instrument and could only be determined with a magnetic field instrument operated at a low mass resolution (R = 300). The reason was found in contamination from bentonites as usually applied for the purification of wines from tarnishing components such as proteins. Therefore, bentonites of different origin were extracted with a reference wine, and an increase of the rare earth element concentrations by more than one order of magnitude was observed in the extracts. The investigation leads to the conclusion that the concentration pattern of the rare earth elements can be strongly affected by the wine producing process and therefore is not generally suitable as a fingerprint for the provenance of wines.     

Long‐Term Stabilization of the Activity of Ascorbate Oxidase Adsorbed on a Porous Carbon Material by Polymaleimidostyrene

Abstract

The biological catalysts adsorbed on the carbon surface gradually lost their activities. In order to prolong stabilization of the enzyme activity, polymaleimidostyrene (PMS) was used to preserve enzyme conformation. Sulfhydryl and amino groups of enzyme or biological tissue can be covalently bound to PMS. By using the carbon material coated by PMS, the stability of L‐ascorbic acid sensor response using purified enzyme was significantly improved, and its initial response was not decreased at all for 150 days, although the purified enzymes adsorbed to the carbon without PMS lost their activity 22.5% after 10 days.