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Biomedical subjects

H Ishiwata

Publications and source records attributed to H Ishiwata.

At least 55 records · Page 3Linked to original sources
PubMed1987

Tetramethylsuccinonitrile in polyvinyl chloride products for food and its release into food-simulating solvents.

The content of tetramethylsuccinonitrile (TMSN), the main decomposition product of 2,2'-azobis-isobutyronitrile, in polyvinyl chloride (PVC) products used for food packaging, were examined as well as food-simulating solvents. The TMSN concentration in 17 PVC products ranged from below the detection limit, 0.05 mg/kg, up to 523 mg/kg. The release of TMSN from two PVC products into five kinds of food-simulating solvents at 60 degrees C for 30 min was observed, except for 1 +/- 1 micrograms/kg of TMSN in n-heptane from a PVC bottle containing 523 +/- 30.4 mg/kg of TMSN. The detection limit of TMSN in the food-simulating solvents was 1 micrograms/kg. When pieces of the bottle were stored in olive oil at 40 degrees C for 120 days, 5 +/- 1 micrograms/kg of TMSN was detected in the oil. The release of TMSN from the pieces of the bottle into olive oil between 80 and 140 degrees C depended on the formula ln y = 0.08786x-5.696, r = 0.9927, where y is the concentration (microgram/kg) of TMSN in olive oil, x is the temperature (degrees C), and r is the correlation coefficient.

Food Contamination↗
PubMed1987

Studies in the guinea-pig stomach on the formation of N-nitrosomethylurea, from methylurea and sodium nitrite, and its disappearance.

The formation of N-nitrosomethylurea (NMU) from methylurea (MU) and sodium nitrite in the guinea-pig stomach and the disappearance of NMU from the stomach were studied using a previously described method for NMU determination (Yamamoto et al. Fd Chem. Toxic. 1986, 24, 247). Guinea-pigs were used since they have only glandular stomachs and the pH of the gastric juice (1-2) is similar to that of humans. NMU was relatively stable in the isolated gastric contents of this species. When 2 mumol NMU was injected into the pylorus-ligated stomach of fasting guinea-pigs, about 50 and 37% of the NMU remained at 20 and 30 min, respectively. Some 19 and 42% remained 30 min after NMU was given orally by stomach tube to fasting and feeding guinea-pigs, respectively. NMU was detected in most blood samples irrespective of the administration procedure, but it disappeared rapidly from the blood after iv injection. Nitrite disappeared rapidly from the pylorus-ligated stomach, residual nitrite being less than 20% of the dose in 2.5 min. when 7.5 mumol MU and 15 mumol NaNO2 were co-injected into the ligated stomach, 3.1 mumol NMU was detected 10 min after the injection, followed by a gradual decrease. When MU and NaNO2 were given orally to the animals, 0.7-1.0 mumol NMU was detected in the stomach 10 min after the treatment. Thus NMU was shown to be formed readily in the stomach of the guinea-pig and to be absorbed from the stomach into the blood.

Animals↗
PubMed1986

Gas chromatographic determination of tetramethylsuccinonitrile in poly(vinyl chloride) products in contact with food.

A method is described for the determination of tetramethylsuccinonitrile (TMSN) in poly(vinyl chloride) (PVC) products in contact with food. TMSN was extracted from PVC with dichloromethane, steam distilled, extracted from the distillate with dichloromethane, then determined with a gas chromatograph equipped with a nitrogen-phosphorus detector and a 6-ft. glass column packed with Chromosorb W coated with 5% Thermon 1000 plus 0.5% phosphoric acid. Recoveries between 98.3 and 100.6% were obtained in the range of 0.5-12.5 ppm of TMSN by the use of nitrobenzene as an internal standard. The detection limit was 0.05 ppm of TMSN in 1 g of PVC products. The highest residue to TMSN found in PVC products in contact with food was 13.9 ppm.

Chromatography, Gas↗
PubMed1986

HPLC determination of N-nitrosomethylurea in biological fluids by reaction with 4-nitrothiophenol.

A simple and sensitive method for the determination of N-nitrosomethylurea (NMU) in biological fluids was developed. The principle is based on the formation of 4-nitrothiophenol methyl thioether (NTP-Me) from 4-nitrothiophenol (NTP) and diazomethane formed from MNU by adding alkali. After sodium hydroxide solution was added to the mixture of NMU in aqueous solution and diethyl ether, the aqueous layer was removed and NTP was added to the ether layer in which diazomethane had been trapped. NTP-Me thus formed was determined by HPLC. This method was successfully applied to the analysis of NMU in biological samples with some clean-up. Stomach and intestine contents and blood samples from guinea-pigs were cleaned up by use of a kieselguhr column followed by heptane-water partition. The recoveries of NMU from the stomach and intestine contents were about 95% and that of NMU from blood samples was about 80%. The detection limit of NMU was 0.5 nmol/g for the stomach contents and 1 nmol/g for the intestine contents and blood samples.

Animals↗
PubMed1986

[Clinical evaluation of cefmenoxime and cefsulodin in chronic complicated urinary tract infections].

To patients with chronic complicated urinary tract infections (UTI) which were in compliance to the UTI standard, cefmenoxime (CMX) was given singly or in combination with cefsulodin (CFS) and efficacies of the respective preparations were examined. Of 53 patients examined, 40 were given CMX alone while 13 were given a combined preparation of CMX and CFS. Results are summarized as follows. With respect to the general clinical effects, 7 patients given CMX alone were markedly improved, 21 improved and 12 unchanged indicating an efficacy rate of 70%. In case of the CMX-CFS combined administration, 2 patients were markedly improved, 7 improved and 4 unchanged giving an efficacy rate of 69%. As for the bacteriological effects, 38 of 54 strains isolated from the patients given CMX alone were eliminated, 4 decreased, 12 unchanged and 15 substituted. Of 16 strains isolated from the patients given the CMX-CFS combined preparation, 4 were eliminated, 2 unchanged and 3 substituted. Thus, incidence of bacterial substitution was low in the combination treatment. The combination of CMX and CFS was more inhibitory to P. aeruginosa than CMX alone. Regarding side-effects, drug eruption was observed in one of the 53 patients and slight elevation of GOT and GPT was recognized in another.

Adult↗