Protocol for high-resolution electrophoresis separation of myosin heavy chain isoforms in bovine skeletal muscle

In this short communication we describe a specific protocol for SDS-PAGE separation of adult bovine myosin heavy-chain (MyHC) isoforms. The conditions defined in this protocol allow a good separation with a good reproducibility of the four MyHC isoforms (MyHC I, IIa, IIx, IIb) identified in adult skeletal muscle of this species. This procedure uses mini-gel electrophoresis system and does not involve preparation of gradient separating gels. In addition, this protocol can also be applied to the electrophoretic separation of ovine and camel MyHC isoforms.     

Synthesis and characterization of new semifluorinated linear and hyperbranched poly(arylene ether phosphine oxide)s through B2 + A2 and AB2 approaches

A new phosphorus containing trifluoromethyl-activated bisfluoro B₂ monomer has been synthesized successfully by coupling reaction of 4-methoxyphenylphosphonic dichloride and the Grignard salt of 5-bromo-2-fluorobenzotrifluoride. This monomer was converted to linear poly(arylene ether phosphine oxide)s by nucleophilic displacement of the fluorine atom on the benzene ring with several diphenols. The B₂ monomer was further demethylated to form an AB₂ monomer which on self condensation yielded hyperbranched poly(arylene ether phosphine oxide) with identical phosphorous containing moiety. The products obtained exhibit weight-average molecular weights as high as 600,000 g mol⁻¹ in SEC. These linear and hyperbranched poly(arylene ether phosphine oxide)s showed thermal stability as high as 516 °C for 10% weight loss in TGA in nitrogen and showed glass transition temperatures up to 253 °C in DSC. All the polymers were soluble in a wide range of organic solvents, e.g., CHCl₃, THF, NMP and DMF, however, the hb sample showed a significant lower solution viscosity compared to linear samples of similar molar mass. Transparent thin films of linear poly(arylene ether phosphine oxide)s casted from dichloromethane exhibited tensile strengths up to 50 MPa, a modulus of elasticity up to 0.95 GPa and elongation at break up to 36% depending on their exact repeating unit structures. No free standing films could be prepared from the hb analogue due to the missing entanglements, but stable thin polymer films on silicon wafers with high hydrophobicity were formed which showed water contact angles as high as 91°.     

Toward new camptothecins. Part 7: Synthesis of thioluotonin and its 5-methoxycarbonyl derivative

The synthesis of thiodeoxyvasicinone and thioluotonin derivatives is described. The results obtained indicate that in these series, oxygen to sulfur replacement leads to absence of strong interaction with topoisomerase I-DNA.     

Phthalocyanine-peptide conjugates via palladium-catalyzed cross-coupling reactions

Phthalocyanines (Pc) were conjugated with peptide moieties to improve their target selectivity for potential use as fluorescence and/or positron emission tomography (PET) probes in medical imaging. Three synthetic methods based on palladium-catalyzed cross-coupling reactions (Sonogashira, Buchwald-Hartwig, and Suzuki-Miyaura) were investigated. Using these methods, a series of peptides monofunctionalized with Pc at the N/C-terminal position or on a phenylalanine side chain was obtained in good yields and characterized.     

Co‐poly(aryl ether sulfone)s containing phthalimidine moiety in the main chain

Several new co‐poly(arylene ether sulfone)s have been prepared by the reaction of 4,4′‐fluorodiphenyl sulfone (FDS) with different bisphenols namely 4,4′‐isopropylidenediphenol (BPA), 4,4′‐hexafluoroisopropylidenediphenol (6F‐BPA), and N‐phenyl‐3,3‐bis(4‐hydroxyphenyl)phthalimidine(PA). The homo‐poly(arylene ether sulfone)s are named as 1a, 2a, and 3a. The copolymers namely 2b, 2c, 2d and 3b, 3c, 3d have been prepared, respectively, on reaction of FDS with BPA or 6F‐BPA using different molar ratios of PA such as 25, 50, and 75. The poly(aryl ether sulfone)s 1a containing PA unit in the main chain showed a very high glass transition temperature of 280°C and an outstanding thermal stability up to 510°C for 5% weight loss under synthetic air. Depending on the mole% of PA, the glass transition temperatures of the copolymers can be varied. The polymers were soluble in a wide range of organic solvents. Transparent thin films of these polymers exhibited tensile strengths upto 84 MPa and Young's modulus up to 3.16 GPa. The films of these polymers showed low water absorption of 0.24%. Copyright © 2009 John Wiley & Sons, Ltd.     

Targeting norovirus infection-multivalent entry inhibitor design based on NMR experiments

Noroviruses attach to their host cells through histo blood group antigens (HBGAs), and compounds that interfere with this interaction are likely to be of therapeutic or diagnostic interest. It is shown that NMR binding studies can simultaneously identify and differentiate the site for binding HBGA ligands and complementary ligands from a large compound library, thereby facilitating the design of potent heterobifunctional ligands. Saturation transfer difference (STD) NMR experiments, spin-lock filtered NMR experiments, and interligand NOE (ILOE) experiments in the presence of virus-like particles (VLPs), identified compounds that bind to the HBGA binding site of human norovirus. Based on these data two multivalent prototype entry-inhibitors against norovirus infection were synthesized. A surface plasmon resonance based inhibition assay showed avidity gains of 1000 and one million fold over a millimolar univalent ligand. This suggests that further rational design of multivalent inhibitors based on our strategy will identify potent entry-inhibitors against norovirus infections.     

Interfacial water with special electron donor properties: effect of water-surfactant interaction in confined reversed micellar environments and its influence on the coordination chemistry of a copper complex

The long-time behavior of the hydrolysis and condensation reaction of the tetraethoxysilane (TEOS) pre-solution at different pH values with and without addition of polyethyleneglycol (PEG) for various aging times was characterized by liquid (1)H, (13)C, and (29)Si NMR spectroscopy. After aging, the alcohol is released in the TEOS pre-solution without addition of PEG at pH 3 and 9. On the other hand, the hydrolysis and condensation rates of the TEOS pre-solutions with addition of PEG at pH 3 and 9 increase except for the TEOS pre-solution with addition of PEG 2000 at pH 9. However, the hydrolysis and condensation rates of the TEOS pre-solutions with and without addition of PEG at pH 5 and 7 are almost the same before and after aging. The effects of the pH values, polymer size and aging times on the hydrolysis and condensation reaction of the TEOS pre-solutions are discussed.     

Small quotients in Euclidean algorithms

Numbers whose continued fraction expansion contains only small digits have been extensively studied. In the real case, the Hausdorff dimension ?? _M of the reals with digits in their continued fraction expansion bounded by M was considered, and estimates of ?? _M for M???? were provided by Hensley (J. Number Theory 40:336?C358, 1992). In the rational case, first studies by Cusick (Mathematika 24:166?C172, 1997), Hensley (In: Proc. Int. Conference on Number Theory, Quebec, pp. 371?C385, 1987) and Vallée (J. Number Theory 72:183?C235, 1998) considered the case of a fixed bound M when the denominator N tends to ??. Later, Hensley (Pac. J. Math. 151(2):237?C255, 1991) dealt with the case of a bound M which may depend on the denominator N, and obtained a precise estimate on the cardinality of rational numbers of denominator less than N whose digits (in the continued fraction expansion) are less than M(N), provided the bound M(N) is large enough with respect to N. This paper improves this last result of Hensley towards four directions. First, it considers various continued fraction expansions; second, it deals with various probability settings (and not only the uniform probability); third, it studies the case of all possible sequences M(N), with the only restriction that M(N) is at least equal to a given constant M ₀; fourth, it refines the estimates due to Hensley, in the cases that are studied by Hensley. This paper also generalises previous estimates due to Hensley (J. Number Theory 40:336?C358, 1992) about the Hausdorff dimension ?? _M to the case of other continued fraction expansions. The method used in the paper combines techniques from analytic combinatorics and dynamical systems and it is an instance of the Dynamical Analysis paradigm introduced by Vallée (J. Théor. Nr. Bordx. 12:531?C570, 2000), and refined by Baladi and Vallée (J. Number Theory 110:331?C386, 2005).     

Sensitive routine liquid chromatography–tandem mass spectrometry method for serum estradiol and estrone without derivatization

The need for a routinely applicable assay to measure low estradiol levels in adult men, postmenopausal women, and young adolescents was recently discussed in an Endocrine Society position statement. Our aim was to develop a sensitive liquid chromatography–tandem mass spectrometry method for estradiol and estrone in human serum without the need for derivatization or extended extraction protocols. After protein precipitation of serum with a mixture of methanol/acetonitrile (85/15) (v/v) containing isotopic internal standards (17β-estradiol-16,16,17-d ₃ and estrone-2,3,4-¹³C), we quantified estradiol and estrone by two-dimensional liquid chromatography–tandem mass spectrometry with electrospray ionization in the negative mode monitoring 5?×?271.20→145.00 (17β-estradiol) and 269.20→145.00 (estrone). Sensitivity was increased by using fluoride and summation of 5 identical transitions for estradiol. Our method was analytically validated, compared against direct immunoassays using serum of 25 adult men, and clinically tested by measuring samples of 3 men at baseline and after chemical castration, 30 postmenopausal women and 15 patients receiving aromatase inhibitors. Total imprecision was below 20 % for the low quality controls. Limit of quantification was 1.3 ng/L (4.8 pmol/L) for estradiol and 1.2 ng/L (4.4 pmol/L) for estrone. Estradiol in Certified Reference Material BCR-576 was within specified uncertainty limits. No significant ion suppression or interference was observed. Our method showed modest correlation with direct immunoassay for estradiol (r ²?=?0.64) but no correlation for estrone (r ²?=?0.12). Patient sample results were within expected ranges. In conclusion, we developed a routinely applicable liquid chromatography–tandem mass spectrometry method for estradiol and estrone measurement which is sensitive enough for use in men, postmenopausal women, and young adolescents.