Souichi Ohta

Comparison of polybrominated diphenyl ethers in fish, vegetables, and meats and levels in human milk of nursing women in Japan

At present, little is known about the occurrence of polybrominated diphenyl ethers (PBDEs) in fish and food products sold in Japan. To investigate whether human exposure to PBDEs through the diet is significant, the concentrations of PBDEs were determined in fish and in meat and vegetables sold in two food markets in the city of Hirakata, Osaka prefecture. The concentrations of PBDEs in the breast milk of 12 primiparae nursing women at one month after delivery also were determined to ascertain the relationship between the levels found in the diet and levels in humans. sigma PBDE concentrations ranged between 21 and 1650 pg/g fresh weight in the edible tissues of five species of fish and one shellfish species. The highest concentrations were measured in yellow-fin tuna, followed by short-necked clam, salmon, yellowtail, mackerel and young yellowtail. Interestingly, sigma PBDE concentrations were not statistically significantly different in two cultured mackerel samples from Japan and mackerel collected from northern European waters. sigma PBDE concentrations in beef, pork and chicken meat (ranging between 6.25 and 63.6 pg/g fresh weight) and in three different vegetables (ranging between 38.4 and 134 pg/g fresh weight) were significantly lower than the concentrations in fish. In human milk, sigma PBDE concentrations ranged between 668 and 2840 pg/g lipid basis, which is comparable to the levels in populations of nursing women reported in Sweden and elsewhere. There was a strong positive relationship between PBDE concentrations in human milk and dietary intake of fish and shellfish, which was established in the women from responses to a questionaire on food consumption habits. The results of this study of food products commonly consumed in Japan and the levels found in nursing women raise a concern about low level PBDE contamination of fish and other foods intended for human consumption.

Long-Term Effects of a Recession at Labor Market Entry in Japan and the United States

We examine effects of entering the labor market during a recession on subsequent employment and earnings for Japanese and American men, using comparable household labor force surveys. We find persistent negative effects of the unemployment rate at graduation for less-educated Japanese men, in contrast to temporary effects for less-educated American men. The school-based hiring system and the dismissal regulation prolong the initial loss of employment opportunities for less-educated Japanese men. The effect on earnings for more-educated groups is also stronger in Japan, although the difference between the two countries is smaller than for less-educated groups.

Assessment of human exposure to PCDDs, PCDFs and Co-PCBs using hair as a human pollution indicator sample I: Development of analytical method for human hair and evaluation for exposure assessment.

Dioxins including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and co-planar polychlorinated biphenyls (Co-PCBs) are highly toxic. Even at environmental pollution levels, they cause hormonal damage in women, and they have been shown to induce immunosuppression and genital function damage in humans. In this study, a new method using isotope dilution was established to detect PCDDs, PCDFs and Co-PCBs in human hair. This method, comprised of washing and cutting of hair, alkaline decomposition, hexane extraction, multilayer silica gel column chromatography, high performance liquid chromatography with a porous graphite carbon column and analysis by high resolution gas chromatography/high resolution mass spectrometry, enabled us to analyze PCDDs, PCDFs and Co-PCBs at trace levels of less than pg/g with good reproducibility. In addition, there was a correlation between some isomers in human hair and blood collected from identical donors. Human hair analysis is useful to evaluate human risk assessment including that due to environmental pollution.

Antibiotic effect of linolenic acid fromChlorococcum strain HS-101 andDunaliella primolecta on methicillin-resistantStaphylococcus aureus

Methanol extracts fromChlorococcum strain HS-101 andDunaliella primolecta strongly inhibited the growth of a strain of methicillin-resistantStaphylococcus aureus (MRSA), which is causing serious problems in Japanese hospitals. So that the anti-MRSA substance(s) could be purified and identified, the growth medium was improved for antibiotic production. When the two strains were cultured in their improved media, antibiotic production byChlorococcum strain HS-101 was 1.8-fold that in the standard BG-11 medium, and production byD. primolecta was 2.3-fold. The activity pattern of fractions eluted by silica-gel or gel-permeation chromatography suggested that both strains produced two antibiotic substances. Identification of the purified substances by NMR and GC-MS showed that one of the active substances in both strains wasα-linolenic acid. Ten fatty acids from other sources were tested, and it was found that unsaturated fatty acids had antibiotic activity against MRSA, with the highest activity that of γ-linolenic acid.

Levels of PCBS, PCDDS and PCDFS in soil samples from incineration sites for metal reclamation in Taiwan

Abstract Surface soil samples from six sites at which waste electric wires and/or magnetic cards are incinerated for metal reclamation in Taiwan, Republic of China, were analyzed for polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). All samples analyzed were contaminated with PCBs at a level of 0.45 to 77 ug/g dry weight, PCDDs at n.d. to 540 ng/g and PCDFs at 1.8 to 310 ng/g. The samples from the incineration sites only with waste electric wire were heavily polluted by these chlorinated chemicals.

Neuroprotection and enhanced recovery with edaravone after acute spinal cord injury in rats.

Study Design. The effect of edaravone, a novel free radical scavenger, was assessed functionally and histologically using a rat spinal cord contusion model. Objective. To investigate the effect of edaravone on neuroprotection after spinal cord injury in rats. Summary of Background Data. The spinal cord injury results in immediate physical damage (primary injury), followed by a prolonged neural tissue disorder (secondary injury). This secondary injury process has been suggested to be induced by lipid peroxidation. Edaravone has been reported to inhibit lipid peroxidation in cerebral ischemia models. Methods. Spinal cord injury at the T10 level was induced with a weight drop device (10 g weight, 25 mm height). Edaravone was administered intravenously as a bolus dose of 5 mg/kg at 5 minutes, 24 hours, and 48 hours after injury (edaravone-treated rats). In control rats, nothing was administered. Functional assessment was conducted weekly using the Basso-Beattie-Bresnahan locomotor rating scores. Histologically, a percentage of spared white matter area was calculated. The effects of intravenous administration of edaravone on lipid peroxide formation in rat spinal cord homogenate were examined using the thiobarbituric acid test for malonyldialdehyde production. Results. Six weeks after injury, edaravone-treated rats showed significantly higher motor score and larger spared white matter area than control rats. The administration of edaravone attenuated malonyldialdehyde production in spinal cord homogenate by >45%. Conclusion. Edaravone enhanced functional recovery and preserved more spinal cord tissue after spinal cord injury in rats. The attenuation of posttraumatic lipid peroxide formation by edaravone partially contributed to this enhancement.

Occurrence of co-planar polybrominated/chlorinated biphenyls (PXBs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in breast milk of women from Spain.

In this study, for the first time, levels and accumulation profiles of eight currently available polybrominated/chlorinated biphenyl congeners (PXBs; XB-77, -105, -118, -126A, -126B, -126C, -156 and -169, named according to IUPAC nomenclature) in human breast milk collected form Spanish women in 2005 were reported. Concentrations and congener specific profiles of polychlorinated biphenyls (PCBs), including co-planar PCBs, (co-PCBs) and polybrominated diphenyl ethers (PBDEs) were also reported. A concentration of 0.45 pg g(-1) lipid weight was found for total PXBs, and arithmetic mean concentrations of 125, 25 and 5.5 ng g(-1) lipid weight were determined for total PCBs, co-PCBs and total PBDEs respectively. Detectable levels of all congeners investigated, except CB-123 and XB-169 were found. Levels of PCBs were similar to those found in Spanish samples collected after 2000, and lower than those obtained before 2000. CB-138, -153 and -180 were the predominant PCB congeners. PBDE levels, dominated by BDE-47, -99, -100 and -209, were lower than PCB levels. PXB concentrations were the lowest, with XB-156 being the most abundant. The concentration levels of PCBs and PBDEs found in this study were in the same range as those from other European countries. Levels of PXBs were much lower than published values determined in Japan which were the only data found in the literature.

Enhancement in fecal excretion of dioxin isomer in mice by several dietary fibers.

The effect of increased nutrients (protein, lipid, vitamins and minerals) on dioxin-induced toxic manifestations such as immune suppression, hepatic hypertrophy, splenic atrophy and enzyme induction was investigated in mice after oral administration of 1,2,3,4,7,8-HxCDD (HxCDD) as one of a representative compound of dioxin isomers. Consequently, it appeared that increased minerals and vitamins in the diet prevented immune suppression by HxCDD. In addition, to clarify the additive effect of nutrients and the ability to hasten the excretion of dioxins by dietary fiber, the adsorbing of dioxins by 16 dietary fibers was investigated by in vitro experiment. Among 16 dietary fibers, locust bean gum, pectin, alginic acid, guar gum, chitin and cellulose were effective in binding dioxin isomers. These dietary fibers also enhanced the fecal excretion of HxCDD in mice.

Anti-Herpes Simplex Virus substances produced by the marine green alga, Dunaliella primolecta

Among 106 microalgae tested, the cytopathic effect (CPE) upon Vero cells of herpes simplex virus, Type 1 (HSV-1) was inhibited by four methanol extracts of Dunaliella bioculata C-523, D. primolecta C-525, Lyngbya sp. M-9 and Lyngbya aerugineo-coerulea M-12. The green alga, D. primolecta, had the highest anti HSV-1 activity, since 10 μg mL-1 of extract from this alga completely inhibited the CPE. This activity was similar to that of acyclovir at the same concentration. We compared anti-viral activities against adeno virus, herpes simplex virus-2 (HSV-2), Japanese Encephalitis and Polio viruses. Only the CPE of HSV-2 was inhibited. Thus, the factor was specific against HSV. The antiviral activity was apparently excited during HSV adsorption and invasion of the cells. We optimized the conditions for anti HSV-1 activity by prolonging the exposure of HSV-1 to the extract. After 2 h, the CPE of even a high titer of HSV-1 (106 TCID50/0.1 mL) was completely inactivated. By use of various chromatographic techniques, three green substances having anti-HSV activity were purified from the algal mass of D. primolecta, and 5 μg mL-1 of this purified substances completely inhibited the CPE. From the analysis of NMR and MS, the chemical structures of the active substances were identified as pheophorbide-like compounds.

Levels of tetrabromobisphenol A, tribromobisphenol A, dibromobisphenol A, monobromobisphenol A, and bisphenol a in Japanese breast milk.

The levels of bisphenol A (BPA) and tetrabromobisphenol A (TeBBPA) were determined in breast milk samples from 19 Japanese mothers. BPA and TeBBPA levels were 36 ng/g lipid (range: 1.4-380 ng/g lipid) and 1.9 ng/g lipid (range: N.D. - 8.7 ng/g lipid), respectively. Tribromobisphenol A (TriBBPA) was similarly detected in all samples (mean: 5.5 ng/g lipid). We investigated the alteration of BPA-related compounds in breast milk over a period of three months. No trend could be observed for time-dependent changes in TeBBPA levels. High levels of TriBBPA were detected in breast milk samples with a high concentration of TeBBPA. We further examined concentration changes in BPA-related compounds in the breast milk of two donors over a period of 24 h. The results suggested that TriBBPA was a debrominated metabolite of TeBBPA, which had been ingested via food consumption and immediately transferred to the breast milk. On the basis of the present results, we estimated and compared the daily intake of BPA, TriBBPA, and TeBBPA from breast milk for infants. The estimated average intake of TriBBPA was 4 times higher than TeBBPA, at 48 and 12 ng/kg/day, respectively. The level of TeBBPA in breast milk was low, suggesting a low risk of causing adverse health effects. In conclusion, the concentration of both TriBBPA and TeBBPA must be determined in breast milk to accurately clarify the exposure of these compounds to infants.