Controlling the lectin recognition of glycopolymers via distance arrangement of sugar blocks.

The arrangement of sugars in glycopolymers contributes to their recognition. The molecular recognition of proteins was controlled by the living radical polymerization of glycopolymers. The glycopolymers were prepared by the copolymerization of propargyl methacrylate (Pr-MA) and triethyleneglycol methacrylate (TEG-MA) via living radical polymerization with a reversible addition-fragmentation glycopolymer chain transfer (RAFT) reagent and by subsequent sugar conjugation by click chemistry. The block copolymers were prepared by the polymerization of Pr-MA and TEG-MA. The molecular recognition of glycopolymers was analyzed using the fluorescence quenching of lectin and found to be dependent on the glycopolymer structures. Two-site binding of glycopolymers to concanavalin A (ConA) was attained by both the glycopolymer with a 105-mer and the tri-block glycopolymer with a 103-mer. Glycopolymers with either a 27- or 54-mer showed much weaker interaction because of one-site binding. The molecular recognition of the glycopolymer was controlled by the arrangement and size of the sugar cluster and not by the sugar density.

Preparation of lecithin microcapsules by a dilution method using the Wurster process for intraarterial administration in gadolinium neutron capture therapy.

Lecithin microcapsules containing gadolinium (Gd) were designed and prepared as a dosage form for intraarterial administration to accumulate Gd in tumors in neutron capture therapy. The microcapsules were composed of 1) a lactose core, 2) a layer of distearylamide of gadopentetic acid (Gd-DTPA-SAm) and polyvinylpyrrolidone (PVP) with or without soybean lecithin (SL) and 3) a membrane containing SL, cholesterol, stearic acid and PVP at three different compositions. A dilution method using the Wurster process was developed for small-scale preparation. In spite of using only 2 g of Gd-DTPA-SAm each, three types of microcapsules were obtained with a content of 24.9% as Gd-DTPA-SAm (3.66% as Gd) even at 150% coating level. The swelling type of microcapsules (MC-D1) did not release Gd at all for the entire 120 min of the experiment in a 0.9% saline solution. On the other hand, the rapid-erosion type (MC-D2) and the vesicle-dispersing type (MC-D3) released Gd with a lag time. The percent released depended on the coating level and the SL content in the Gd-fixing layer. A large number of droplet-like particles spouted out, and/or tubular vesicles formed with MC-D2 and MC-D3 in the saline solution. These phenomena implied that the water-insoluble Gd-DTPA-SAm would be entrapped in these particles/vesicles. When MC-D2 and MC-D3 were administered to normal rats via the hepatic artery, a Gd-accumulation as high as 70 and 71% of the injected dose was detected in the whole liver 2 h after administration. In addition, biochemical and histological evaluation of the liver after administration indicated that embolization of the microcapsules actually occurred in the blood vessels, and that necrosis induced by ischemia was not serious. These results suggested that administration of these microcapsules might be multiply repeated in order to accumulate the required amount of Gd in tumors.

Modified agar dilution susceptibility testing method for determining in vitro activities of antifungal agents, including azole compounds.

In vitro activities of antifungal agents, including azole compounds, against yeasts were easily determined by using RPMI-1640 agar medium and by incubating the plates in the presence of 20% CO2. The end point of inhibition was clear by this method, even in the case of azole compounds, because of the almost complete inhibition of yeast growth at high concentrations which permitted weak growth of some Candida strains by traditional methods. MICs obtained by the agar dilution method were similar to those obtained by the broth dilution method proposed by the National Committee for Clinical Laboratory Standards.

Effect of additives on dissolution and swelling of soybean lecithin microcapsules prepared using the Wurster process.

Microcapsules whose membranes contained soybean lecithin (SL), cholesterol (CH), stearic acid (SA) and polyvinylpyrrolidone (PVP) at various compositions were prepared. Then, dissolution and swelling behaviors of the microcapsules in a 0.9% saline solution were studied to be related to the phase diagram of three components containing 42% of PVP in anhydrous state. In the aqueous solution, when an anhydrous microcapsule membrane was composed of SL not saturated with both CH and SA, the microcapsules showed rapid release of carbazochrome sodium sulfonate (CCSS, a model drug), poor particle-swelling and spouting of droplets containing CCSS. Long-delayed release of CCSS and drastic particle-swelling with no spouting of droplets were observed when the anhydrous membrane was composed of SL saturated with both CH and SA and the composition was not close to the two-component line, CH-SA, or to the saturation line. The spouting of droplets would be attributable to the CH and/or SA-poor SL phase and to the SL phase which dissolved CH and SA, but contained either CH or SA only in a small amount, and the delayed release would be due to the CH and SA-rich SL phase dissolving a great amount of CH and SA formed by hydration. The degree of release suppression and particle-swelling depended on the SL content. At 20-45% of SL content, the prolonged-release, great particle-swelling and no spouting of droplets at the early stage were observed only when the CH and SA-rich SL phase formed by hydration contained a high content of CH and SA.

Design and preparation of ethyl cellulose microcapsules of gadopentetate dimeglumine for neutron-capture therapy using the Wurster process.

Microcapsules of hygroscopic, highly water-soluble gadopentetate dimeglumine (Gd-DTPA-DM) for use in preliminary in vivo experiments for neutron-capture therapy were designed. They were prepared with such properties as a particle size small enough to be suspended and injected through a syringe, a negligible release of Gd-DTPA-DM, and a high drug content by means of the Wurster process, a spray coating method using a spouted bed with a draft tube. They were composed of lactose cores of 53-63 microm, an undercoat of ethyl cellulose (EC) and polyvinylpyrrolidone (PVP), a drug-layer of Gd-DTPA-DM, EC and PVP, a waterproof coat and a release-sustaining overcoat of EC and cholesterol (1:1), and a surface treated with hydrogenated egg lecithin. By curing at 110 degrees C for 30 min after mixing with 20% pulverized mannitol powder, the 20% overcoating suppressed the release of Gd-DTPA-DM from 75-106 microm microcapsules to less than 10% for the first 20 min, which was the period required to prepare a suspension, inject it and irradiate the neutron. The microcapsules could be used to confirm that the intracellular presence of Gd is not critical in gadolinium neutron-capture therapy.

Computer simulation of agglomeration in the Wurster process.

A simplified model for computer simulation of agglomeration in the Wurster coating process was constructed using droplet size distribution and the relation between the size of agglomerates and the number of primary particles composing them experimentally determined. Computer simulations were applied to the cases where a 2.5% aqueous solution of hydroxypropyl cellulose (containing sodium carboxymethyl cellulose of 10% on a dry basis) was sprayed on four kinds of sharply fractionized lactose powders between 32 and 75 microns. With cores larger than 53 microns, the agitation exerted on particles strongly suppressed the growth of agglomerates, but the fraction of produced agglomerates reached about 50%. The smallest droplet size that was contributable to agglomeration (critical droplet size) was estimated to be 37.1-49.0 microns, increasing with core size, and the weight fraction of droplets larger than this critical size was only 0.5-2.7%, decreasing with increase in core size. The production of even such a minor amount of coarse droplets could be responsible for significant agglomeration.

The effect of combinations of cefotiam and other antibiotics on methicillin-resistant Staphylococcus aureus in vitro.

The in-vitro activities of cefmetazole, flomoxef, imipenem, vancomycin and enramycin alone and in combination with cefotiam against eighteen clinically isolated methicillin-resistant Staphylococcus aureus was investigated. Cefotiam, cefmetazole, flomoxef and imipenem inhibited the growth of clinical isolates at concentrations ranging from 100 to 1600, 6.25 to 400, 6.25 to 400 and 0.78 to 200 mg/L, respectively. Synergic effects were observed with combinations of cefotiam and cefmetazole, flomoxef or imipenem against more than 70% of the strains. The fractional inhibitory concentration (FIC) index values were less than 0.1. Vancomycin and enramycin alone inhibited the growth of all strains at concentrations ranging from 0.39 to 1.56 mg/L and 0.2 to 0.78 mg/L, respectively. Moreover, vancomycin and enramycin in combination with cefotiam showed synergy against strains in which no synergic effects were observed when cefotiam was combined with other beta-lactam agents. About 50% of the strains tested were inhibited synergically by cefmetazole, flomoxef or imipenem, at clinically relevant concentrations in combination with 0.78 mg/L of cefotiam. The effects of vancomycin or enramycin in combination with cefotiam on the growth of a homogeneous resistant clone, which was derived from one of the clinical isolates, TS-65, was also studied. Regrowth in the presence of vancomycin or enramycin alone was suppressed when cefotiam was added.