Polymorphism directed

Tan RM, Zehnbauer B, Picus J et al. TYMS genotype polymorphism directed neoadjuvant chemora-diation for patients (pts) with T3/T4 adenocarcinoma of the rectum (Abstract). 2006Gastrointestinal Cancers Symposium 2006. 

Because the short oligonucleotides are able to prime reproducible amplification from a variety of genomes under the specified conditions, it is possible to develop a panel of universal primers that can be used to detect polymorphism directly in practically any organism using only nano-gram quantities of genomic DNA. 

Yuki N. Campylobacter sialyltransferase gene polymorphism directs clinical features of Guillain-Barre syndrome. / Neurochem. 2007 103(Suppl 1) 150-158. 

The easiest and usually most precise quantification of polymorphic composition is achieved when a sensitive heteronucleus (such as fluorine or phosphorus) is present in the molecule, and its spectrum shows chemical shift differences between the polymorphs. Direct polarization experiments of these nuclei are sensitive, and therefore the polymorphs can be quantified quickly directly from the peak ratios. The limit of quantification can be well below 1% of one form in the presence of other forms. As an added advantage, the spectra of these nuclei are usually very simple to analyze, since only a very limited number of resonances are typically present in the spectrum. 

L-Amino acid acylase from Aspergillus melleus (Amano acylase 30000) was used to hydrolyze racemic 6-acetoxybuspirone to (5)-6-hydroxybuspirone 2 in 96% enantiomeric excess (EE) after 46% conversion. The remaining (l )-6-acetoxy-buspirone with 84% EE was converted to (l )-6-hydroxybuspirone 2 by acid hydrolysis [28]. The EE of both enantiomers could be improved to more than 99% by crystallization as a metastable polymorph. Direct hydroxylation of buspirone to (5 )-6-hydroxbuspirone by Streptomyces antibioticus ATCC 14980 has also been described [28]. 

Fig. 3. The main crystallographic forms of siUca stable at atmospheric pressure. The vertical directions represent the facile, displacive polymorphic transitions, whereas the horizontal directions represent the sluggish reconstmctive transitions (44).

Various polymorphs have been reported for SnS with band gap widths in the range 1.0-1.5 eV, depending on the preparation method. The a-SnS (herzenbergite) is the most frequently occurring phase and is a p-type semiconductor with a direct optical transition at 1.3 eV and a high absorption coefficient (> 10" cm ). The orthorhombic S-SnS phase possesses a direct gap between 1.05 and 1.09 eV. 

Second, x-ray diffraction will, directly, give spacings in the crystal and reveal differences between samples. Finally, solubility curves can be carried out, and if a nick in the solubility curve is found (Fig. 9), this is a transition temperature. If no nick is found, there is no transition temperature, but if the dissolution curves are as shown in Fig. 5, there is polymorphism, and it may... 

The classic disilene 1 is unusual in that it exists in at least three crystalline modifications orange and yellow unsolvated forms and a yellow toluene solvate (Fig. 2). The orange polymorph has a helical conformation in which all of the mesityl substituents are twisted in the same direction thus molecules of 1 in this form are chiral.51 The toluene solvate has an unusual conformation in which two mesityl rings cis to each other are nearly coplanar with the Si=Si bond, while the other two cis mesityl groups are nearly orthogonal.41 The structure of the yellow unsolvated form is not yet known. Because of the flat potential surface for the Si=Si... 

Hoekstra, R., Criado-Fomelio, A., Fakkeldij, J., Bergman, J. and Roos, M.H. (1997) Microsatellites of the parasitic nematode Haemonchus contortus polymorphism and linkage with a direct repeat. Molecular and Biochemical Parasitology 89, 97-107. 

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