Oxidation of 5-hydroxy-2'-deoxyuridine into isodialuric acid, dialuric acid, and hydantoin products

Oxidation products of cytosine, including 5-hydroxycytosine and 5-hydroxyuracil, are highly susceptible to subsequent oxidation. Here, the oxidation products of 5-hydroxy-2'-deoxyuridine have been studied by NMR and MS analyses. The initial products were diastereomers of isodialuric acid nucleoside. These products subsequently decomposed into corresponding dialuric acid derivatives at neutral pH. The position of the carbonyl and hydroxyl groups, at C5 and C6 for isodialuric acid and at C6 and C5 for dialuric acid derivatives, respectively, was determined by 1H- and 13C NMR analyses. In addition, these analyses revealed that the carbonyl groups of both isodaluric and dialuric acid derivatives exist in their fully hydrated form in aqueous solution. Finally, the dialuric acid derivatives were observed to undergo subsequent decomposition into the corresponding 5-hydroxyhydantoin derivatives. Studies of a trinucleotide containing 5-hydroxyuracil suggest that the reactions described herein for the monomer can be extrapolated to DNA.     

Tandem functionalization of nonactivated alkenes and alkynes in intramolecular N-acyloxyiminium ion carbocyclization. Synthesis of 6-substituted hydroindole 2-carboxylic acids

[reaction: see text] Five-membered N-Boc acyliminium ions derived from L-pyroglutamic acid harboring 4-butenyl and 4-butynyl tethers undergo Lewis acid-mediated halo and tandem Friedel-Crafts carbocyclization within minutes at -78 degrees C to give stereodefined 6-substituted octahydroindole and hexahydroindole 2-carboxylic acid methyl esters, respectively. The cyclic vinyl bromides are excellent substrates for Pd-catalyzed Suzuki-Miyaura, Heck, and Stille couplings. The method also provides access to enantiopure sp2- and sp3-arylated azabicyclics that are novel and versatile scaffolds for chemical diversification.     

Bicomplex Quantum Mechanics: I. The Generalized Schrödinger Equation

We introduce the set of bicomplex numbers which is a commutative ring with zero divisors defined by where We present the conjugates and the moduli associated with the bicomplex numbers. Then we study the bicomplex Schr?dinger equation and found the continuity equations. The discrete symmetries of the system of equations describing the bicomplex Schr?dinger equation are obtained. Finally, we study the bicomplex Born formulas under the discrete symmetries. We obtain the standard Born’s formula for the class of bicomplex wave functions having a null hyperbolic angle.     

On block Gaussian sketching for the Kaczmarz method

Numerical Algorithms - The Kaczmarz algorithm is one of the most popular methods for solving large-scale over-determined linear systems due to its simplicity and computational efficiency. This...     

Aerosol lenses propagation model

We propose a model based on the properties of cascading lenses modulation transfer function (MTF) to reproduce the irradiance of a screen illuminated through a dense aerosol cloud. In this model, the aerosol cloud is broken into multiple thin layers considered as individual lenses. The screen irradiance generated by these individual layers is equivalent to the point-spread function (PSF) of each aerosol lens. Taking the Fourier transform of the PSF as a MTF, we cascade the lenses MTF to find the cloud MTF. The screen irradiance is found with the Fourier transform of this MTF. We show the derivation of the model and we compare the results with the Undique Monte Carlo simulator for four aerosols at three optical depths. The model is in agreement with the Monte Carlo for all the cases tested.     

Laser direct writing of combinatorial libraries of idealized cellular constructs: Biomedical applications

The ability to control cell placement and to produce idealized cellular constructs is essential for understanding and controlling intercellular processes and ultimately for producing engineered tissue replacements. We have utilized a novel intra-cavity variable aperture excimer laser operated at 193 nm to reproducibly direct write mammalian cells with micrometer resolution to form a combinatorial array of idealized cellular constructs. We deposited patterns of human dermal fibroblasts, mouse myoblasts, rat neural stem cells, human breast cancer cells, and bovine pulmonary artery endothelial cells to study aspects of collagen network formation, breast cancer progression, and neural stem cell proliferation, respectively. Mammalian cells were deposited by matrix assisted pulsed laser evaporation direct write from ribbons comprised of a UV transparent quartz coated with either a thin layer of extracellular matrix or triazene as a dynamic release layer using CAD/CAM control. We demonstrate that through optical imaging and incorporation of a machine vision algorithm, specific cells on the ribbon can be laser deposited in spatial coherence with respect to geometrical arrays and existing cells on the receiving substrate. Having the ability to direct write cells into idealized cellular constructs can help to answer many biomedical questions and advance tissue engineering and cancer research.     

The rodrigues type representations for a certain class of special functions

Summary An attempt is made here to present a systematic introduction to and several applications of a certain method of obtaining Rodrigues type representations for a fairly wide variety of sequences of special functions. The main results, contained in Theorems2 and3 below, are shown to apply not only to the Bessel polynomials, the classical orthogonal polynomials including, for instance, Hermite, Jacobi (and, of course, Gegenbauer, Legendre, and Tchebycheff), and Laguerre polynomials, and to their various generalizations studied in recent years, but also to such other special functions as the Bessel function and a certain class of generalized hypergeometric functions. Entrata in Redazione il 25 giugno 1977. This work was partially supported by the National Research Council of Canada under grants A-7353 and A-4027. For a preliminary report of this paper see Notices Amer. Math. Soc.,24 (1977), p. A-238, Abstract no. 77T-B43.     

A road traffic noise pattern simulation model that includes distributions of vehicle sound power levels

Annoyance, sleep disturbance and other health effects of road traffic noise exposure may be related to both level and number of noise events caused by traffic, not just to energy equivalent measures of exposure. Dynamic traffic noise prediction models that include instantaneous vehicle noise emissions can be used to estimate either of these measures. However, current state-of-the-art vehicle noise emission models typically consider a single emission law for each vehicle category, whereas measurements show that the variation in noise emission between vehicles within the same category can be considerable. It is essential that the influence of vehicles that are producing significantly more (or less) noise than the average vehicle are taken into account in modeling in order to correctly predict the levels and frequency of occurrence of road traffic noise events, and in particular to calculate indicators that characterize these noise events. Here, an approach for predicting instantaneous sound levels caused by road traffic is presented, which takes into account measured distributions of sound power levels produced by individual vehicles. For the setting of a receiver adjacent to a dual-lane road carrying free flow traffic, the effect of this approach on estimated percentile levels and sound event indicators is investigated.     

A luminescent sensor for tyrosine phosphorylation

We have developed a luminogenic probe for tyrosine phosphorylation based on a short peptide sequence containing an iminodiacetate moiety near the site of phosphorylation. In response to kinase activity, the probe provides a strong luminescence enhancement, resulting from the increased ability of the probe to bind and sensitize Tb3+ and Eu3+ ions upon phosphorylation.     

Total synthesis of iejimalide A-D and assessment of the remarkable actin-depolymerizing capacity of these polyene macrolides

A concise and convergent total synthesis of the highly cytotoxic marine natural products iejimalide A-D (1-4) is reported, which relies on an effective ring-closing metathesis (RCM) reaction of a cyclization precursor containing no less than 10 double bonds. Because of the exceptional sensitivity of this polyunsaturated intermediate and its immediate precursors toward acid, base, and even gentle warming, the assembly process hinged upon the judicious choice of protecting groups and the careful optimization of all individual transformations. As a consequence, particularly mild protocols for Stille as well as Suzuki reactions of elaborate coupling partners have been developed that hold considerable promise for applications in other complex settings. Moreover, a series of non-natural "iejimalide-like" compounds has been prepared, differing from the natural lead in the polar head groups linked to the macrolide's N-terminus. With the aid of these compounds it was possible to uncover the hitherto unknown effect of iejimalide and analogues on the actin cytoskeleton. Their capacity to depolymerize this microfilament network rivals that of the latrunculins which constitute the standard in the field. Structural modifications of the peptidic terminus in 2 are thereby well accommodated, without compromising the biological effects. The iejimalides hence constitute an important new class of probe molecules for chemical biology in addition to their role as promising lead structures for the development of novel anticancer agents.