Microencapsulation by way of simple coacervation by gelatin was examined. Five kinds of core material and six kinds of coacervation-inducing agent (CIA) were chosen and the encapsulability of each combination was studied. Some core materials are easily encapsulated, others are difficult to encapsulate, and some show a dependency of encapsulability on the CIA. Electrophoresis and gelatin adsorption studies revealed that encapsulation by way of simple coacervation by gelatin is caused by the affinity between core and coacervate resulting from gelatin adsorption on the core surface. These studies further revealed that cores onto which a large amount of gelatin has been adsorbed before coacervation can be encapsulated.

Adsorption↗

PubMedDate not supplied

Core treatment for improving microencapsulability in simple gelatin coacervation method.

In microencapsulation by way of simple coacervation by gelatin, some core materials are encapsulated easily, whilst others are difficult to encapsulate or show an encapsulability dependent on the coacervation-inducing agent. The treatment of core materials to improve encapsulability was studied. It was found that core particle encapsulability can be improved by recrystallization from aqueous solution of an ionic polymer. Electrophoresis, microscopical observation and pH dependency of encapsulability of recrystallized cores revealed that the electrostatic attractive force between gelatin molecules in solution and a polymer attached to the core particle cause gelatin adsorption on the core surface to result in a great improvement in encapsulability.

Carbazilquinone↗

PubMedDate not supplied

A new concept for interpretation of first-order release from albumin microspheres.

A release mechanism from a microsphere that consisted of a water-swellable polymer and a uniformly dispersed, relatively small number of very slightly soluble large-core particles was considered. When the microsphere is dipped in release media the polymer swells instantly, and every core particle dissolves in the release media in the space between the core particles and the swollen polymer to make a saturated solution. It is assumed that Fickian diffusion of dissolved core substance between all spaces filled with saturated solution and outer sink occurs independent of each other, and release from one entire microsphere is the sum of diffusion from all spaces in the microsphere. Then, derived theoretical release kinetics is found to be first-order, and the derived first-order release rate constant is expressed as a function of the following parameters: radius of core particle, radius of the microsphere, solubility of core substance to media solution, density of the core particle, and permeability constant of core substance in swollen polymer. When rate constants were measured from release tests, varying each parameter, the relation between constants and each parameter follows the function. The permeability constant, which was calculated applying the function on measured rate constants and other known parameters, was in good agreement with the permeability constant measured from permeation study of planar membrane prepared in similar conditions to when preparing microspheres. These results are thought to show the validity of the mechanism and function proposed.

Carbazilquinone↗

PubMedDate not supplied

An analysis of first-order release kinetics from albumin microspheres.

Release rates from BSA microspheres prepared from various conditions are analysed using a previously reported equation expressing the first-order release rate constant. The permeability constants calculated applying the equation on experimental release rates are in good agreement with the constants measured from permeation studies using planar membrane, for various preparation conditions. It is shown that the equation expressing the first-order release rate constant is valid more extensively. The permeability constant varies depending on the preparation conditions, and the reason for variation is shown clearly to be the difference in degree of swelling of the polymer. It was found from regression analysis that there is relatively simple correlation between unknown parameters of the equation and the preparation conditions. Release rate constants can be calculated applying the equation on the known parameters and the estimated values of the unknown parameters from the correlation. Good agreement was found between the calculated values and experimental ones; therefore, at least as far as we examined here, the release rate constant of the microsphere can be estimated from the preparation conditions.

Carbazilquinone↗

PubMedDate not supplied

Takayasu's arteritis with transient clubbed finger.

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Adult↗

PubMedDate not supplied

Change of cerebral glucose metabolism by antineoplastic drug.

To estimate change of cerebral glucose metabolism by anticancer drugs, positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) was performed in 11 patients with malignancies who did not show neurological symptoms. In a patient treated with intravenous high-dose methotrexate (HD-MTX) and intrathecal MTX, apparent decrease of glucose metabolism was observed. HD-MTX and intrathecal MTX may cause cerebral glucose metabolism disorder primarily. Cerebral glucose metabolism was also mildly reduced by chemotherapy with drugs other than MTX and by radiotherapy outside the brain, with a corresponding change of blood data. It may reflect a psychosomatic change in whole body.

Aged↗

PubMedDate not supplied

Determination of residual cephalexin in chick tissues by Bacillus stearothermophilus paper disc assay.

A paper disc method is described for determination of residual cephalexin (CEX) in chick tissues. A trichloroacetic acid extract of plasma and tissues is chromatographed on a macroreticular resin (Diaion HP-20) column to remove endogenous antibacterial substances interfering with the assay. The eluate is evaporated to dryness and the residue, dissolved in methanol-water (1 + 2), is subjected to a paper disc assay using Bacillus stearothermophilus var. calido-lactis C953 NIZO as a test organism. The detection limit was 0.0375 ppm in tissue; the average recovery of CEX ranged from 72.4% in skin to 90.4% in plasma. Water containing 200 or 500 mg/L of CEX was given ad libitum to 2-week-old chicks for 10 days; the highest levels of CEX were found in the kidney, and the lowest were found in muscle at 0 h of withdrawal. CEX disappeared from most tissues at 24 h after withdrawal except from skin of chicks given 500 mg/L. However, the drug was not detected in the skin at 48 h after withdrawal.

Adipose Tissue↗

PubMedDate not supplied

Liquid chromatographic method for determining the macrolide antibiotic sedecamycin and its major metabolites in swine plasma and tissues.

A liquid chromatographic (LC) method was developed to determine sedecamycin, a 17-membered macrolide antibiotic used for treating swine dysentery, and its major metabolites (lankacidin C, lankacidinol A, and lankacidinol) in swine plasma and tissues. Plasma is directly extracted with ethyl acetate and analyzed by liquid chromatography without purification. Tissues are homogenized in a phosphate buffer containing sodium chloride, and then extracted with ethyl acetate. The extracts are subjected to silica gel-Florisil, double-layered column chromatography to remove endogenous interfering substances. The LC determination uses silica gel and ODS-silica as a stationary phase. The detection limits for sedecamycin and its metabolites were less than or equal to 0.05 ppm, and average recoveries and coefficients of variation (0.2-1 ppm range) were greater than 75% and less than 10%, respectively.

Animals↗