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Osmotic pressures of concentrated solutions of polystyrenes with different molecular weights in good solvents were determined by a vapor pressure method. The data obtained as well as the osmotic pressure data in the literature were analyzed based on the scaling theory and the theory of Flory and Huggins. It was shown that the crossover between semidilute and concentrated solutions takes place at a critical concentration C** (0.15-0.2 g/cm3), irrespective of molecular weight.

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DR-3355, the S-(-)-isomer of ofloxacin, was generally twice as potent as ofloxacin against a variety of gram-positive and gram-negative pathogens, and its action was bactericidal. The compound was characterized by having the highest level of activity against staphylococci, Bacteroides fragilis, and Peptococcus spp. of the fluorinated quinolones tested, including ofloxacin, ciprofloxacin, fleroxacin, and NY-198. The activity of DR-3355 was not affected by different media, inoculum size, or human serum, but decreased under acidic conditions at pH 5.0 or in human urine.During the past decade, the development of fluorinated quinolones such as norfloxacin (6), ofloxacin (10), ciprofloxacin (12), fleroxacin (3), and NY-198 (4) has been aimed mainly at enhancing activity against gram-negative and gram-positive pathogens. Among these compounds, ofloxacin (10) is characterized chemically by a tricyclic structure with a methyl group at the C-3 position in the oxazine ring, thus providing an asymmetric center at this position (Fig. 1). In the course of studies on the structure-activity relationships between stereochemistry and activity, two optically active isomers of ofloxacin, i.e., DR-3355 [S-(-)-ofloxacin] and DR-3354 [R-(+)-ofloxacin], were prepared successfully by use of their optically resolved synthetic intermediates ( Fig. 1) (2). A preliminary study of the spectrum of activity of these isomers against selected laboratory strains revealed that DR-3355 was 8 to 128 times more potent than DR-3354 and approximately twice as active as ofloxacin (2). In this paper we describe the in vitro activity of DR-3355, relative to other fluorinated quinolones, against a large number of clinical isolates. MATERIALS AND METHODSCompounds. DR-3355 and ofloxacin were synthesized at the Research Institute, Daiichi Seiyaku Co., Ltd., Tokyo, Japan, as were ciprofloxacin, fleroxacin, and NY-198. Methicillin sodium (Banyu Pharmaceutical Co., Ltd., Tokyo, Japan) and clindamycin phosphate (Japan Upjohn Ltd., Tokyo, Japan) were commercial products.Organisms Ofloxacin: R = -CH3

Comb-Shaped Polystyrenes 57 perturbation produced by the individual bead is the same in both chains. Some support for this argument is provided by the fact that the intrinsic viscosities of the dimer and the 16-mer both tend to be low or high in the same solvents (e.g., low in DMSO, THP, and methanol and high in water and 6 M urea), indicating that the solvent-solute interactions are similar for the short and the long chain. Thus although the absolute level of intrinsic viscosity may be difficult to interpret in terms of the hydrodynamic specific volume of the oligomer, the ratio DjWfaL may be taken as a measure of the relative chain expansion in a given solvent.

We measured the serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble E-selectin (sE-selectin) and soluble intercellular adhesion molecule-1 (sICAM-1) in 72 patients with systemic lupus erythematosus (SLE) (including patients with active nephritis) and 33 normal control subjects, to investigate the correlation between levels of adhesion molecules and disease and histological activity. Serum samples were obtained at the time of renal biopsy in 27 patients with lupus nephritis. The 27 patients were divided into groups according to the World Health Organization (WHO) class as follows: class I + II, n = 11; class III + IV, n = 13 and class V, n = 3. We also determined the activity index (AI) in these 27 renal biopsy specimens. We obtained serial measurements of the serum levels of soluble adhesion molecules in 11 patients to examine the difference between active and remission stages. The serum level of sVCAM-1, but not sE-selectin or sICAM-1, was correlated with parameters of SLE disease activity, including the SLE disease activity index score, the anti-double stranded DNA antibody titer, the C3 level, the C4 level and the CH50 level. The serum levels of sVCAM-1, sE-selectin and sICAM-1 were significantly higher in patients with SLE than in controls (P = 0.006, P = 0.0005 and P = 0.04, respectively). The serum level of sVCAM-1 was significantly higher in patients with active lupus nephritis (WHO classes III and IV) than in patients in inactive lupus nephritis (WHO classes I and II) (P = 0.0016). The sVCAM-1 level was significantly elevated in patients with an AI > or = 4 compared with patients with an AI < 4 (P = 0.0025). The sVCAM-1 level decreased significantly during remission (P = 0.0033). The serum level of sVCAM-1 was elevated in patients with active lupus nephritis (WHO classes III and IV) and in patients with high AI scores. The serum level of sVCAM-1 was correlated with the SLE disease activity and decreased during remission. Therefore, the sVCAM-1 level may be a useful marker of lupus nephritis activity.

Minn., for providing the Dow Coming Co. 11100 and 21600 a,u;-divinyl PDMS samples.Professor Macosko also performed the mercuric acetate titrations on the a,o>divinyl PDMS.

Second virial coefficients and expansion factors of monodisperse poly(a-methylstyrenes) covering a wide range of molecular weight are determined by light scattering measurement in andsolvents and are compared with current theories of these solution properties. It is concluded that the Flory theory of cV-type is valid when the molecular weight is high enough to permit reliable determination of the radius of gyration.