Decompositions of complete bipartite and tripartite graphs into selfcomplementary factors with finite diameters

We completely determine the spectrum of the complete bipartite and tripartite graphs that are decomposable into two isomorphic factors with a finite diameter.1991 Mathematics Subject Classification. 05C70     

Multiple sample amplification and genotyping integrated on a single electronic microarray

We report a novel method that allows simultaneous in situ amplification and then genotyping of single nucleotide polymorphism (SNP) for multiple samples on a single electronic microarray. The locus coding for one of the common inherited thrombosis risk factors, Factor V Leiden (FVL), was chosen as a model system for SNP analysis. This method combines strand displacement amplification (SDA) with electrophoretic movement and concentration of DNA on electronic microarrays to provide a single platform for DNA amplification and analysis. The method includes: electronic anchoring of allele-specific SDA amplifiable primers (APs) and a nonamplifiable primer (NAP) to different electrodes, electronic hybridization of genomic DNA from different samples to those primers, in situ amplification of target DNA, and genotyping of FVL. Compared to previous anchored SDA methods, the addition of a NAP improves detection signals by at least 20-fold. The sensitivity of this method is dependent on the amplification time. Using this method, nine different genomic DNA samples with known FVL genotypes were amplified and correctly genotyped on a single electronic microarray without any contamination between samples. The present method could streamline development of nucleic acid-based assays in applications of molecular diagnostic, point-of-care testing, and forensic detection, which often require the capability to analyze multiple samples efficiently.     

New tools for molecular imaging of redox metabolism: development of a fluorogenic probe for 3 alpha-hydroxysteroid dehydrogenases

A new fluorogenic substrate was developed for 3alpha-hydroxysteroid dehydrogenases (3alpha-HSD), including the human enzymes implicated in important physiological functions (androgen deactivation, neurosteroid activation). While ketone 5 is nonfluorescent, the corresponding alcohol exhibits high fluorescence with emission maximum at 510 nm, thus constituting a redox optical switch. This study began with a chemical concept of a ketone-alcohol optical switch which guided the synthesis of a focused array of compounds. Subsequently, seven compounds were selected (1-7) on the basis of their optical and chemical (stability) properties and were submitted to a screen against a panel of dehydrogenase enzymes. Probe 5 was found to be highly selective for bacterial, rat, and human 3alpha-HSD enzymes. The kinetic parameters were obtained for human 3alpha-HSD enzyme (type 2 isozyme, AKR 1C3; Km = 2.5 muM, kcat = 8.2 min-1). Remarkably, comparison to 5alpha-dihydrotestosterone (5alpha-DHT, Km = 26 muM, kcat = 0.25 min-1, Figure 4), a likely physiological substrate in prostate, revealed that synthetic probe 5 is in fact a far better substrate for this enzyme. Structure 5 represents an exciting lead for the development of a redox imaging probe.     

Total synthesis of (-)-rhazinilam: asymmetric C[bond]H bond activation via the use of a chiral auxiliary

The antitumor agent (-)-rhazinilam was synthesized in three major steps, namely the pyrrole synthesis, selective C[bond]H bond activation, and direct macrolactam formation. The key step involved asymmetric C[bond]H bond functionalization (dehydrogenation) of the diethyl group segment in intermediate 6. This was achieved by the attachment of chiral platinum complexes to the proximal nitrogen atom. A high degree of selectivity (60-75% ee) was achieved via the use of oxazolinyl ketone chiral auxiliaries.     

Symmetry-breaking defect in coupled dipole-proton system of hydrogen-bonded ferroelectric

We consider the coupled dipole-proton system of hydrogen-bonded ferroelectric crystal with one defect dipole that is coupled more strongly with the protons than the original dipole. This defect dipole simulates the symmetry-breaking defects that are often introduced in the crystals as probes in the electron paramagnetic resonance (EPR) experiments. A particular attention is paid to the explanation of strong isotope effects that have been detected in the measurements of static and dynamic properties of the pure crystals and the symmetry-breaking defects. We suppose that the isotope effects are caused by the isotope-dependent tunneling energy and we analyze behavior of the system with and without the defect in two adiabatic approximations that correspond to the case when the protons tunnel faster than the dipoles oscillate and to the opposite case. These two approximations lead to the two models which predict different properties the pure crystals and the symmetry-breaking defects.     

Affecting of aquatic vascular plant Lemna minor by cisplatin revealed by voltammetry

Within the context of application of platinum derivates based effective cytostatics, we can suppose that these risk metals can get into aquatic ecosystems where they can show biologic availability for food chain. In the present work we report on investigation of affecting of duckweed (Lemna minor) by various doses of cisplatin (0, 5, 10, 20, 40, 80 and 160 microM) for 4 days. The toxic influence of cisplatin was evaluated on the basis of growth inhibition expressed as number of leaves, growth rate, and total amount of biomass. The result value of 96hEC50, calculated from growth inhibition with comparison of growth rates, was 6.93 microM. Moreover we aimed on determination of cisplatin content using differential pulse voltammetry. The highest content of cisplatin (320 ng g(-1) of fresh weight) was determined in plants treated by 80 microM at the second day of treatment. Plants protect themselves against heavy metals by means of synthesis of cysteine-rich peptides such as glutathione and phytochelatins. Thus thiol determination in the treated plants by means of Brdicka reaction followed. The marked increase in thiol concentration detected is associated with defence reaction of the plant against stress caused by cisplatin.     

Longevity and other practical benefits of monolithic silica columns in the analysis of samples with complex matrices

At the turn of the millennium, the monolithic columns invoked new chances in HPLC. Even more than their organic polymer-based siblings, the inorganic silica-based monoliths targeted the territory of classical fully porous particle-packed columns, promising many benefits. Based on the number of published articles, the monoliths attracted academics just in the first few years after their introduction to the market. Lately, as superficially porous particles and sub-2-micron fully porous particles dominated the market, they stayed in the focus of routine laboratories and those who really appreciated the high porosity of the monolithic bed. The monoliths' practical benefits cannot be easily traced in the literature when they gradually lose academics' interest. Nevertheless, after more than 20 years of our experience, we still favor silica monoliths for their low back pressure and longevity when analyzing samples of clinical, pharmaceutical, and environmental origin. At the same time, the high permeability of monoliths enabled the birth of sequential injection chromatography, the medium-pressure separation technique based on the flexible flow manifold. This minireview aims to check, discuss, and summarize the practical aspects of monolithic silica columns in HPLC and medium-pressure sequential injection chromatography (SIC) that may not be visible at first sight but are evident retrospectively.