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Biomedical subjects

H Ishiwata

Publications and source records attributed to H Ishiwata.

At least 37 records · Page 2Linked to original sources
PubMed1996

Binding and uptake of liposomes containing a poly(ethylene glycol) derivative of cholesterol (stealth liposomes) by the macrophage cell line J774: influence of PEG content and its molecular weight.

The binding and intake of liposomes containing a different molar content and chain length of a PEG-Chol derivative had been studied in cultured macrophage cell line J774. The decrease in binding and endocytosis of the liposomes containing PEG-Chol is dependent on (i) the PEG chain length, (ii) the molar content of the surfactant, (iii) the liposome concentration in the external medium. The best results in reducing the uptake of liposomes were obtained by a PEG-Chol liposome suspension with a high molar content (25%) which presents a non negligible amount of free PEG-Chol. Moreover, we could show an increase by 2 for binding and by about 5 for endocytosis of filtrated-liposomes containing 25 mol% of 8800PEG-Chol, in the absence of free PEG-Chol in the suspension. Binding and intake of control liposomes was also inhibited in the presence of free PEG-Chol. Fluid phase endocytosis of SRh was inhibited up to 45% of control in the presence of liposomes containing PEG-Chol or free PEG-Chol. Based on the comparison of 4400PEG-Chol with the most commonly used PEG derivative 5000PEG-PE, PEG-Chol is more powerful in terms of reducing their binding and endocytosis by J774 cells. Inhibition of the fluid phase endocytic process is attributed to the binding of PEG-Chol to the cells' plasma membrane inducing a decrease in surface hydrophobicity of the cells, resulting in a marked decrease in the extent of phagocytic ingestion.

Animals↗
PubMed1996

Comparison of official methods for 'readily oxidizable substances' in propionic acid as a food additive.

The official methods for 'readily oxidizable substances (ROS)' in propionic acid as a food additive were compared. The methods examined were those adopted in the Compendium of Food Additive Specifications (CFAS) by the Joint FAO-WHO Expert Committee on Food Additives, FAO, The Japanese Standards for Food Additives (JSFA) by the Ministry of Health and Welfare, Japan, and the Food Chemicals Codex (FCC) by the National Research Council, USA. The methods given in CFAS and JSFA are the same (potassium permanganate consumption). However, by this method, manganese (VII) in potassium permanganate was readily reduced to colourless manganese(II) with some substances contained in the propionic acid before reacting with aldehydes, which are generally considered as 'readily oxidizable substances', to form brown manganese (IV) oxide. The FCC method (bromine consumption) for 'ROS' could be recommended because it was able to obtain quantitative results of 'ROS', including aldehydes.

Aldehydes↗
PubMed1996

[Efficacy of the chemosensitivity test using collagen gel matrix-supported culture system for urogenital tumors].

BACKGROUND: We evaluated the usefulness of in vitro tumor culture system using a specialized collagen gel matrix (CGM assay) as a chemosensitivity test. PATIENTS AND METHODS: Chemosensitivity results of CGM assay were compared with other in vivo and in vitro assays on an implantable murine bladder tumor cell line (MBT-2). In addition we investigated the possibility of the clinical use of CGM assay using clinical specimens obtained from urogenital malignant tumor patients by comparing the result with that of the other chemosensitivity test, SDI testing using single cells (conventional SDI test). Methods of CGM assay were as follows. Tumor tissues on the collagen gel matrices were incubated under the existence of anticancer drugs following 4 days preculture. Drug sensitivities were evaluated by counting the number of viable cells adjusted to the tumor weight. RESULTS: Inhibition rates in MBT-2 were high in the order of mitomycin C, cisdiamminedichloroplatinum (II), (2"R)-4'-0-tetrahydropyranyl adriamycin. Four of 6 anticancer drugs were decided as chemosensitive drugs. These results corresponded to the results of the antitumor effects on subcutaneously transplanted MBT-2 in vivo, moreover was correlated well with those of the conventional SDI test. Twenty of 22 cases, including 11 of 13 bladder cancer cases, 1 of 3 renal cancer cases, 2 of 3 testicular cancer cases and 1 of 1 adrenal cortical cancer cases, were evaluable in the clinical study of the CGM assay. Corresponding rates between the results of the CGM assay and those of the conventional SDI test performed simultaneously in 12 cases were excellent for each anticancer drug. CONCLUSION: This CGM assay can serve as an effective tool for chemosensitivity testing because of its convenience and high evaluable rate.

Animals↗
PubMed1995

Urinary bladder carcinogenesis induced by melamine in F344 male rats: correlation between carcinogenicity and urolith formation.

Urinary bladder carcinogenesis associated with melamine treatment was examined with concomitant use of NaCl to allow assessment of the relationship between uroliths and lesion development. Analysis of the chemical composition of calculi was also performed. F344/DuCrj male rats received diets containing 3 or 1% melamine alone or in combination with either 10 or 5 % NaCl, or 10% NaCl alone for 36 weeks, and then diet without NaCl supplement for a further 4 weeks. The water intake, used as an index of urinary output, was increased by NaCl treatment. The incidences of bladder transitional cell carcinomas and papillomas were 90 and 55% in the group treated with 3% melamine alone; 0 and 15% in the group treated with 3% melamine and 10% NaCl; and 21 and 42% in group treated with 1% melamine alone; and zero in the other groups. Calculus formation resulting from melamine administration was suppressed dose-dependently by the simultaneous NaCl treatment, along with the occurrence of hyperplasia of the papilla in the kidneys. The main constituent of calculi were melamine itself and uric acid (total contents 61.1-81.2%), contained in equal molar ratio. The results indicate that melamine-induced proliferative lesions of the urinary tract of rats were directly due to the irritative stimulation of calculi, and not molecular interactions between melamine itself or its metabolites with the bladder epithelium.

Animals↗
PubMed1995

Physical-chemistry characteristics and biodistribution of poly(ethylene glycol)-coated liposomes using poly(oxyethylene) cholesteryl ether.

Poly(ethylene glycol)-coated liposomes were prepared with poly(oxyethylene) cholesteryl ethers (mPEG-Chol). PEG unit numbers tested were 50, 100 and 200, of which the average molecular weights (m) of PEG were 2200, 4400 and 8800, respectively. Properties of both PEG-coated liposomes and PEG-Chol molecules were investigated. These liposomes exhibited a long circulation time in the blood after i.v. injection in rats, estimated by both the lipid membrane marker, L-alpha-dipalmitoylphosphatidylcholine [2-palmitoyl-9,10-3H](3H-DPPC), and an internal aqueous marker, 3H-inulin. Accumulation in the liver and spleen at 8h-post-injection was significantly reduced compared with conventional liposomes. The percentage of PEG-Chol incorporation in liposomal membranes was also investigated. Liposomes composed of egg yolk phosphatidylcholine (EPC)/PEG-Chol at various molar ratios were separated from free PEG-Chol molecules, which are not incorporated in liposomal membranes by chromatography over Sepharose CL-4B columns, PEG-Chol incorporation reached approx. 14 and 18 mol% of the total lipids with 25% PEG-Chol unit numbers of 200 and 50, respectively. The occupied area per molecule of PEG-Chol was larger than that of Chol, and the fluorescence anisotropy (r) of the initial 25 mol% (8800)PEG-Chol liposomes was smaller than that observed for 12.5 mol% Chol liposomes. PEG-coated liposomes containing calcein were incubated at 37 degrees C in heat-inactivated fetal bovine serum (FBS). In the presence of FBS, calcein leakage was increased with PEG-Chol percentage incorporation and an increase in FBS concentration. The amount released from PEG-coated liposomes represented 60% at maximum and was larger than that of the control liposomes. PEG-Chol molecules are interesting compounds since they can be easily synthesized in a large amount on an industrial scale. The basic physical-chemistry characteristics investigated in this article are critical to assess the pharmacological application of PEG-Chol liposomes as drug delivery systems.

Animals↗
PubMed1995

[Inspection of carbon monoxide in imported tilapia].

Carbon monoxide in imported tilapia was determined with a gas chromatograph equipped with a molecular sieve 13x column (2.3 m), a methanizer and a FID for the inspection of imported food. The concentration of carbon monoxide in the sample, which was vacuum packed and suspected to be treated with carbon monoxide, was 16 x 10 micrograms/kg in fish meat, and 37 x 10(3) microliters/l in the bubble in the package. On the other hand, carbon monoxide in the reference, which was vacuum packed but was not treated with carbon monoxide, was 10 micrograms/kg in fish meat and 76 microliters/l in the bubble in the package. Carbon monoxide was less than 4 micrograms/kg in two vacuum packed fish meat of tilapia sold in a market in Tokyo. From these results, the suspected sample was concluded to be treated with carbon monoxide for color fixating of protoheme in fish meat.

Carbon Monoxide↗
PubMed1994

[Studies on the stability of ferrous ion in the feeds added iron lactate during storage].

Studies on the stability of ferrous ion in the feeds added iron lactate were conducted for a chronic toxicity test. No significant changes in contents of ferrous ion were observed in all samples when feeds containing 0.2 and 5% of iron lactate were stored in the dark at room temperature (25 +/- 2 degrees C) for 72 hours, or feeds containing 1 and 2% iron lactate stored at 4 degrees C for 90 days.

Animal Feed↗
PubMed1993

[Elution of lead and cadmium from imported gold-decorated glassware].

Lead and cadmium were known to be eluted from some imported gold-decorated glassware, which was bonded at a quarantine station. Elution of lead and cadmium was confirmed to be occurred from the gold-decorated portion, but not from glass itself. No elution of these heavy metals was observed from gold-decorated glassware in the market.

Cadmium↗
PubMed1992

[Study on mandibular position in occlusion during opening and closing movement in hemimandibulectomy patients--effect of difference of opening distance on mandibular position].

In the hemimandibulectomy patients the mandible is severely deviated and the occlusion is unstable, therefore the prosthodontic treatment for these patients is generally not successful. To investigate the stability of the mandibular position in occlusion of these patients, the differences of the range and the position of the mandible in occlusion between during the 5-mm opening and closing movement and during the 10-mm movement were analyzed three-dimensionally with the Jaw Movement Analyzer MM-JI-E. In this study, four hemimandibulectomy patients were selected as the subjects. The findings were as follows: 1. In three subjects, the range of the mandible in occlusion during the 10-mm opening and closing movement was larger than that during the 5-mm movement in almost all directions. On the contrary in one subject, the range of the mandible in occlusion during the 10-mm opening and closing movement was smaller than that during the 5-mm movement in almost all directions. 2. The relative relationship of the mandibular position in occlusion during the 10-mm opening and closing movement to that during the 5-mm movement varied in four subjects. In one subject, the mandible rotated horizontally towards the outside and moved upward. In another subject, the mandible rotated horizontally towards the inside and moved downward. In the other subject, the mandible moved inward and upward. In the other subject, the mandible moved outward and downward.

Aged↗
PubMed1992

[Food hygienic indexes on biodegradable polymers].

Current specifications for food packaging made of polyolefine plastics were applied to biodegradable plastics. No lead and cadmium were detected in any biodegradable plastic samples with the exception of bacterial cellulose, which contained trace amounts of lead and cadmium. Potassium permanganate consumption amount was less than the current specification level for polyofines. Sugars leached from bacterial cellulose was 22 +/- 1 microgram per 100 cm2 as glucose, and amino acids leached from poly-gamma-methylglutamate films was 8 +/- 3 micrograms per 100 cm2 as glutamic acid.

Amino Acids↗
PubMed1992

[Migration test of lead and cadmium from plastic wares in contact with food].

Release of lead and cadmium from plastic tableware was examined. Samples were treated with 2 ml of 4% acetic acid or 0.1N HCl per cm2 of the surface area at 60 degrees C or 95 degrees C for 30 min. No migration of lead and cadmium from samples containing up to 391 ppm lead or 6863 ppm cadmium was observed.

Cadmium↗
PubMed1992

[Determination of volatile substances and leachable components in polystyrene food contact wares].

Material and migration tests of food-contact plastic wares made of polystyrene were carried out. The average concentration of volatile substances (sum of toluene, ethylbenzene, isopropylbenzene, n -propylbenzene, and styrene) in materials was 861 +/- 692 ppm. Styrene was observed in 95% of 19 samples. alpha-Methylstyrene, which is one of the material compounds of polystyrene, was detected in one sample. Release of volatile substances into n-heptane was not observed at the detection limits of 0.1 ppm.

Cooking and Eating Utensils↗
PubMed1991

Migration and material tests of some food-contact plastic wares made in Thailand.

Migration and material tests of food-contact plastic wares were carried out in compliance with the Thai Food Act. Sample materials studied were melamine resin, polyethylene, polypropylene, polystyrene, and polyvinyl chloride. Migration levels of phenol, formaldehyde, colors and heavy metals were determined. A test for vinyl chloride monomer in polyvinyl chloride was carried out. Migrant and residual levels in all samples were in compliance with the Act.

Cooking and Eating Utensils↗
PubMed1989

[Antimony and other heavy metals in metallic kitchen ware].

The antimony in metallic kitchen ware was determined. The content of this element in metals used for the production or repairing of utensils, containers and packaging which come in contact with foods is regulated and should be less than 5% in under the Japanese Food Sanitation Law. In eight metallic samples, antimony was detected in solder used for the production of a can for green tea and an eggbeater. The contents were 1.30% in the former and 1.90% in the latter. No antimony was detected in solder used for a cookie cutter. A sample of solder used for electric work, not for food utensils, contained 0.81% of antimony. In other metallic utensils which come in contact with food such as aluminum foil, a brass spoon, a stainless steel fork, a wire netting, and an iron rock for vegetable color stabilizing, antimony was not detected at a 0.05% detection limit. A qualitative test using rhodamine B also showed positive results in only three solder samples. Lead concentrations in solder used for the kitchen ware were from 39.3 to 51.3%. These concentrations were higher than the limit (20%) of lead content by the Law. No cadmium was detected in any samples.

Antimony↗