For Chiron

The symbol for Chiron looks like a letter K balanced on a circle or oval. It resembles an old-fashioned key. 

Dale E Johnson BSc PharmD PhD DABT is Vice President, Preclinical Development for Chiron Corporation, Emeryville, California, where he heads the worldwide non-clinical development effort for biotechnology products and small... 

Besides the MDL Molfile formal, other file formats are often used in chemistry SMILES has already been mentioned in Section 2.3.3. Another one, the PDB file format, is primarily used for storing 3D structure information on biological macromolecules such as proteins and polynucleotides (Tutorial, Section 2.9.7) [52, 53). GIF (Crystallographic Information File) [54, 55] is also a 3D structure information file format with more than three incompatible file versions and is used in crystallography. GIF should not be confused with the Chiron Interchange Formal, which is also extended with. cif. In spectroscopy, JCAMP is apphed as a spectroscopic exchange file format [56]. Here, two modifications can be... 

Early implementations of the CIP rules for computer detection and specification of chirality were described for the LHASA [105], CHIRON [106], and CACTVS [107] software packages. Recently, several commercial molecular editors and visualizers (e.g., CambridgeSoft s ChemOffice, ACD s I-Lab, Accelrys WebLab, and MDL s AutoNom) have also implemented the CIP rules. 

Superoxide dismutase has been approved by the FDA for preventing reperfusion injury or damage to donor organ tissue (178). This enzyme is prepared by recombinant DNA technology and marketed by Bristol-Myers and Pharmacia-Chiron. 

For excellent discussions of the use of optically active starting materials in synthesis, see (a) Hanes-sian, S. The Total Synthesis of Natural Products. The Chiron Approach, Pergamon Press New York, 1983 (b) Scott, J.W. In Asymmetric Synthesis, Morrison, J.D. Scott, J. W., Eds., Academic Press San Diego, 1984, Vol. 4, p. 1. 

Addition of such a-lithiosulfinyl carbanions to aldehydes could proceed with asymmetric induction at the newly formed carbinol functionality. One study of this process, including variation of solvent, reaction temperature, base used for deprotonation, structure of aldehyde, and various metal salts additives (e.g., MgBrj, AlMej, ZnClj, Cul), has shown only about 20-25% asymmetric induction (equation 22) . Another study, however, has been much more successful Solladie and Moine obtain the highly diastereocontrolled aldol-type condensation as shown in equation 23, in which dias-tereomer 24 is the only observed product, isolated in 75% yield This intermediate is then transformed stereospecifically via a sulfoxide-assisted intramolecular 8, 2 process into formylchromene 25, which is a valuable chiron precursor to enantiomerically pure a-Tocopherol (Vitamin E, 26). 

Chiron et al. used HPLC/ESI-MS in the negative mode for the determination of acidic herbicides in environmental waters. The acidic herbicides investigated were benazolin, bentazone, 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-... 

For a discussion of this approach to enantioselective synthesis, see S. Hanessian, Total Synthesis of Natural Products The Chiron Approach, Pergamon Press, New York, 1983. 

The accuracy of any quantitative assay depends on the use of standards that have been thoroughly characterized by accepted and independent methods. Without careful preparation of standards, the reported values for samples will be systematically higher or lower than the true value. Chiron has devoted considerable effort to the development of gold standard preparations of RNA from HIV-1 and HCV and DNA from HBV for use in the bDNA assays. These standards have been made available to the U.S. Food and Drug Administration and the World Health Organization. 

Kapke, G. F et al. (1997). Comparison of the Chiron quantiplex branched DNA (bDNA) assay and the Abbott genostics solution hybridization assay for quantification of hepatitis B viral DNA. J. Viral Hepat. 4,67-75. 

Chemical Reaction. Chemical reaction of particulate material generates stresses within the particle that can lead to fracture. In the case of gas-solid reactions, the particle degradation is also desired because it accelerates the reaction by extending the reactive surface. A relevant commercial example is the particle degradation of solid fuels in combustion processes. This latter topic has been studied by Massimilla and coworkers extensively. The reader is referred for further details to a review given by Chirone et al. (1991). 

Chiron S, Papilloud S, Haerdi W, Barcelo D (1995) Automated online liquid-solid extraction followed by liquid chromatography-high-flow pneumatically assisted electrospray mass-spectrometry for the determination of acidic herbicides in environmental waters. Anal Chem 67(9) 1637-1643... 

Chiron S, Alba AF, Barcelo D (1993) Comparison of online solid-phase disk extraction to liquid-liquid-extraction for monitoring selected pesticides in environmental waters. Environ Sci Technol 27(12) 2352-2359... 

Examples are the synthesis of prostaglandin F2 and erythronolide A (8) from D-glucose, by Stork [20] and Hanessian [19] and their coworkers, respectively, whose retrosynthetic pathways are shown in Schemes 9.9 and 9.10. For more details concerning this strategy, known as "the chiron approach", see the book by Hanessian [19]. 

Post-column introduction of a sheath liquid gives more flexibility to the selection of pH values for a mobile phase. Chiron et al. applied post-column addition of tripropylamine to reduce the acidicity of the mobile phase in their study of bentazone and chlorophenoxyacetic acids to enhance ESI negative ion signals. Apffel et al." on the other hand, introduced propionic acid/isopropanol to displace TEA in the mobile phase, and improved the ESI positive ion signals. 

Aiming at the pyranose form of sugars, normal type hetero-Diels-Alder reactions were extensively used for the synthesis of functionally substituted dihydropyran and tetrahydropyran systems (5-10) (see routes A - D in the general Scheme 1) which are also important targets in the "Chiron approach" to natural product syntheses (2.) Hetero-Diels-Alder reactions with inverse electron demand such as a, p-unsaturated carbonyl compounds (l-oxa-1,3-dienes) as heterodienes and enol ethers as hetero-dienophiles, are an attractive route for the synthesis of 3,4-dihydro-2H-pyrans (11). 

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