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Biotech / Medical : XOMA. Bull or Bear? -- Ignore unavailable to you. Want to Upgrade?

To: Robert K. who wrote (8717)	2/14/1999 8:50:00 PM
From: aknahow	Read Replies (1) \| Respond to of 17367

Bob, this link has no value in terms of stock performance. You and a few others might find it of interest. crystal.chem.ruu.nl also ceid.ox.ac.uk

To: Robert K. who wrote (8717)	2/15/1999 11:52:00 AM
From: aknahow	Respond to of 17367

ANCA/BPI wieslab.se

To: Robert K. who wrote (8717)	2/15/1999 12:06:00 PM
From: aknahow	Respond to of 17367

Bob, SLGONZALEZ, etc. (lectures, posters) For full site use links at very top. This URL takes one to somehting that seems like BPI spelled backwards.<g> faf.cuni.cz 2nd European Symposium On Antimicrobial Agents: Mechanism Of Action And Structure-Activity Relationship July 1 - 4, 1998, Hradec Kralove, Czech Republic END OF ONE MYTH IN MICROBIOLOGY K. Waisser1, P. Jilek2 1Department of Inorganic and Organic Chemistry, Faculty of Pharmacy, Charles University, CZ 500 05 Hradec Kralove, Czech Republic 2Department of Biological and Medicinal Sciences, Faculty of Pharmacy, Charles University, CZ 500 05 Hradec Kralove, Czech Republic Introduction Lien et al.1 claimed that on in vitro evaluation of antibacterial activity, the optimum hydrophobicity expressed as the logarithm of the partition coefficient in the system of octanol-water is approximately 4 in agents active against gram-negative bacteria, whereas against gram-positive bacteria it is approximately 6. He related this effect to the composition of the cell wall, which is more lipophilic in gram-negative bacteria and there is therefore a larger barrier for the penetration of hydrophobic drugs into cells. He did not, however, examine any mycobacterial strains. This fact about the optimum hydrophobicity of gram-positive and gram-negative mycobacteria was found its way into a number of textbooks. Results and discussion Recently we reviewed QSAR studies of antimycobacterial activity of certain substances2. Mycobacteria posses a highly lipophilic cell walls. The surface of cell in some strains is nearly of wax character. One would therefore assume that the values of optimum hydrophobicity for antimycobacterial agents acting within mycobacterial cells must be, quite logically according to Lieno deduction1, even lower than 4. But we found that there was no „ideal hydrophobicity“ of antimycobacterial substances. According to this fact we decided to revise the Lien¥s conclusion. We have found that there are no general „ideal hydrophobicity“ of antibacterial substances against gram-negative and against gram-positive bacteria as well. Bacteria Compounds log Popt Bacteria Compounds logPopt S. aureus phenols 8.15 S. typhy phenols 4.5 (gram-pos.) pyridinium salts 3.0 (gram-neg.) amonium salts 2.5 3-alkyl- pyrazoles 4.6 2-hydroxy- alkanoic acides 1.04 amines 2.62 Conclusion There is no general „ideal hydrophobicity“ for gram-negative, and for gram-positive bacteria, as well. References 1.Lien E. J., Hansch C., Anderson S. M.: Structure-Activity correlation for antibacterial agents on gram-positive and gram-negative cells. J. Med. Chem. 11, 430-441 (1968) 2.Waisser K.: QSAR in drug design - Antituberculotics. Folia Pharm. Univ. Carol. 19, 83-89 (1995) The work was supported by grant grant 203/96/0262 of the Grand Agency of Czech Republic