In vivo characteristics of low molecular weight copolymers composed of L-lactic acid and various DL-hydroxy acids as biodegradable carriers for drug delivery systems.

Low molecular weight and amorphous copolyesters composed of 70 mol% L-lactic acid and 30 mol% DL-hydroxy acids such as DL-lactic acid, DL-alpha-hydroxy-n-butyric acid, DL-alpha-hydroxyisovaleric acid and DL-alpha-hydroxyisocaproic acid were synthesized by direct copolycondensation in the absence of catalysts, to evaluate their in vivo capabilities as biodegradable carriers for drug delivery systems. For this purpose, the copolyester was moulded into a small cylindrical specimen under melt-pressing technique and implanted subcutaneously in the back of male adult rats. The in vivo degradation pattern can be subdivided into three types: the formations of parabolic type (L-LA/DL-HBA copolymer), linear type (L-LA/DL-LA copolymer) and S type (L-LA/DL-HIVA and L-LA/DL-HICA copolymers).

Measurement of (90)Sr in environmental samples by cation-exchange and liquid scintillation counting.

A new method for the measurement of (90)Sr in environmental samples by cation-exchange and liquid scintillation counting is described. Strontium carbonate is purified by precipitation and ion-exchange, weighed for the determination of chemical yield, dissolved in hydrochloric acid and mixed with the liquid scintillator, Aquasol-2. Two channels of a low-background liquid scintillation counter are used to determine (90)Sr, (90)Y and (89)Sr, free from the effects of environmental tritium.

In vivo characteristics of low molecular weight copoly (D,L-lactic acid) formulations with controlled release of LH-RH agonist.

Amorphous and crystalline copolymers with a relatively low molecular weight of 1800 were synthesized by direct copolycondensation of D-lactic acid and L-lactic acid in the absence of a catalyst, to evaluate their in vivo capabilities as biodegradable carriers for drug delivery systems. A luteinizing hormone-releasing hormone agonist, des-Gly10-(D-Leu6)-LH-RH ethylamide, was incorporated in a fine cylindrical copolymer formulation, under melt-pressing technique, a mild heat-pressure condition. This formulation was implanted subcutaneously in the back of male rats.

Migration of radionuclides controlled by several different migration mechanisms through a sandy soil layer.

Column experiments have been carried out on the migration of 60Co and 137Cs through a sandy soil layer in order to examine the migration of radionuclides controlled by several different migration mechanisms. Radionuclide concentration distribution between the effluent and the sandy soil layer was measured after 10 L of the solution containing the radionuclides were introduced into the column from the top of the layer at a constant flow rate. Most of the 60Co and 137Cs remained attached to the layer, and a small amount of each radionuclide; at concentrations of 0.

In vivo release of cisplatin from a needle-type copolymer formulation implanted in rat kidney.

Cisplatin, cis-dichlorodiamine platinum (II), was incorporated in a needle-type copolymer formulation (0.8 mm diameter, 6 mm long) by radiation-induced polymerization. The copolymer used was copoly(diethylene glycol dimethacrylate/polyethylene glycol #600 dimethacrylate, 80/20 vol%).

[A twin type heat flow microcalorimeter for radioactivity measurement].

A microcalorimeter is described which was developed and tested for measuring the activity of pure beta particle emitters. Two identically made calorimeter cells are used, each 46.5 mm i.

[Dosimetry by a cellulose triacetate film dosimeter in proton-beam irradiation].

The basic characteristics of cellulose triacetate (CTA) film dosimeter have been investigated with 5, 8, and 15 MeV proton beams. The optical density change per unit absorbed dose for 8 and 15 MeV protons is the same as that given for electron beams, but a little smaller for 5 MeV protons. The CTA dosimeter was found to be useful to obtain dose distributions with high spatial resolution in samples exposed to proton beams.

Continuous cellulase production by immobilized Sporotrichum cellulophilum and continuous saccharification of bagasse.

Immobilized Sporotrichum cellulophilum with nonwoven materials was cultured continuously by a rotating-disk fermentor to supply cellulase into the saccharification system. The filter paper activity (5.0) was retained after 696 h under conditions of 250 rpm stirring and 0.

Liquid-liquid extraction separation and sequential determination of plutonium and americium in environmental samples by alpha-spectrometry.

A procedure is described by which plutonium and americium can be determined in environmental samples. The sample is leached with nitric acid and hydrogen peroxide, and the two elements are co-precipitated with ferric hydroxide and calcium oxalate. The calcium oxalate is incinerated at 450 degrees and the ash is dissolved in nitric acid.

Nature of yeast cells immobilized by radiation polymerization. Activity dependence on the water content of polymer carriers.

Higher activity of ethanol production due to higher density of yeast cells was observed in yeast cells immobilized with artificial polymer carriers of higher water content based on methoxypolyethyleneglycol methacrylate and 2-hydroxyethylacrylate. These polymer carriers were prepared by radiation-induced polymerization below 0 degrees C. Yeast cells were immobilized with these carriers by adsorption method during multiplication.

Periodical batch culture of the immobilized growing fungi Sporotrichum cellulophilum producing cellulase in the nonwoven materials.

The thermophilic fungus Sporotrichum cellulophilum was immobilized with nonwoven materials for cellulase production. The cellulose powder concentration in the medium was an important factor controlling cellulase production. When the cellulose powder concentration in the nonwoven materials was more than 4%, cellulase production was suppressed.

Verification of certified sulphur values in steel reference materials by isotope-dilution mass spectrometry, and characterization of sulphur present on the solid samples.

Sulphur in a number of steel reference materials has been determined by isotope-dilution mass spectrometry, utilizing both open-beaker and sealed-tube dissolution techniques. It is confirmed that the sulphur present in most samples can be completely converted into sulphate by the conventional open-beaker dissolution technique. The results on reference materials are in good agreement with the certified values for BCS samples and the recent or revised certified values for JSS and NBS samples.

Cellulase production from immobilized growing cell composites prepared by radiation polymerization.

The cellulase production from immobilized Trichoderma reesei composites prepared by radiation polymerization at low temperature was studied. The production of cellulase from the cells irradiated by radiation was slightly retarded at the initial stage of the culture, but was immediately recovered. The production of cellulase resulting from the growth of the immobilized cells proceeds efficiently in the composite having a porous polymer matrix, in which the productivity of cellulase varied with the hydrophilicity, the shape of the composite, monomer, and cell concentration.

Stabilization of Photosystem II (O(2) Evolution) of Spinach Chloroplasts by Radiation-induced Immobilization.

Spinach chloroplasts were immobilized with vinyl monomers by radiation-induced polymerization at low temperature and stored in buffer containing bovine serum albumin. The lifetime of O(2) evolution activity in photosystem II was prolonged remarkably in immobilized chloroplasts. Thermostability of immobilized chloroplasts stored in buffer containing bovine serum albumin was far better than that of immobilized chloroplasts in pure buffer and that of intact chloroplasts.

Cooling of extraction electrode of an ion source in long-pulse operation.

Experimental studies were made on the cooling of extraction electrodes of an ion source in the case of long-pulse operation. Copper electrodes with forced water cooling pipes were tested under the condition that an ion beam of 1 to 5 A at 30 keV was extracted for up to 10 s. The average heat loading to the grid are of the electrode was as high as 130 W/cm2.

Accurate determination of sulphur in steels and certain heat-resisting alloys by isotope dilution mass spectrometry.

A mass spectrometric isotope dilution method for the determination of sulphur in steels and certain alloys has been investigated. Addition of bromine in the dissolution of carbon steels was necessary for the complete conversion of sulphur into sulphate. The relative standard deviation was better than 1.

Immobilization of Glucose Isomerase-Containing Streptomyces phaeochromogenes Cells in Fine-Particle Form.

A new preparation method for immobilizing Streptomyces phaeochromogenes cells in fine-particle form was investigated using radiation-induced polymerization at low temperatures with previously salted out hydrophilic monomers. Using this method, it was found that the glucose isomerase activity of the immobilized cell particles was markedly higher than that of immobilized cells in block form obtained without salting out of the monomer. The diameter of the particles was varied by changing the irradiation temperature or the concentrations of monomer and salt.

Drive characteristics of a fast movable limiter in the JT-60 tokamak.

A pair of fast-acting movable limiters are to be installed in the vacuum chamber of the JT-60 tokamak being designed at JAERI. Their purpose is to suppress skin current in the plasma column. They should travel across the vacuum chamber over a stroke of about 1 m in 0.