Neurologic features of chronic minamata disease (organic mercury poisoning) and incidence of complications with aging

Abstract

To elucidate the neurologic features of chronic Minamata disease, and the incidence of complications with aging, we studied 80 patients with documented Minamata disease (organic mercury poisoning) from 1986 to 1994 (mean age: 63 years). Of the cardinal neurologic findings, sensory impairment was seen with highest frequency in 98.8% of patients limited to the extremities in 86.3%. Impairment of lower extremity coordination was observed in 60%, constriction of the visual field in 51.9%, and retrocochlear hearing loss in 41%. To assess age‐related complications, patients were separated into three groups by age: Group I (10 to 39 years); Group II (40 to 69 years); Group III (≥7 0 years). The incidences of hypertension and cerebrovascular diseases, organic ophthalmologic disorders (including cataracts), presbyacusis, and cervical spondylosis deformans increased significantly with age. Compared with a preceding survey (1981 to 1985, 171 patients, mean age: 63.5 years), the incidences of complicated hypertension and cataracts had decreased, whereas those of cerebrovascular disease and retinitis pigmentosa remained unchanged. The incidences of abnormal brain computed tomography (CT), presbyacusis, cervical spondylosis deformans, and positive tests for urine sugar also increased. The incidences of these complications other than retinitis pigmentosa were similar to those in the general population. These results accurately reflect the recent epidemiological disease tendencies in Japan toward a decreased incidence of hypertension and an increased incidence of diabetes.     

Association of serum levels of polychlorinated biphenyls with IL-8 mRNA expression in blood samples from asthmatic and non-asthmatic Japanese children

Background

One of the suggested health outcomes of PCB exposure is childhood asthma.

Objectives

This study was conducted to find health relevant biomarkers providing the molecular epidemiological evidence for the positive relationship between exposure to PCBs and childhood asthma.

Methods

Blood samples from fifteen asthmatic children as well as an equal number of non-asthmatic children (average 2 year old) were collected, and were analyzed for PCBs and their select marker expression by using qRT-PCR.

Results

Among biomarkers examined IL-8 expression was significantly correlated to serum levels of PCB #163 + 164 (P = 0.022), #170 (P = 0.046), #177 (P = 0.022), #178 (P = 0.022) and #180 + 193 (P = 0.046) in a dose-dependent manner, which was found only among asthmatic children. In contrast, COX-2 correlations to individual congener levels were recognized only among control subjects, not among asthmatic subjects.

Conclusion

Serum concentrations of PCB#163 + 164, #170, #177, #178 and #180 + 193 correlate significantly with IL-8 mRNA expressions among asthmatic children.     

The possibility of sustainable pest management by introducing bio-diversity: simulations of pest mite outbreak and regulation

Since the late 1980s, spider mite pests have caused serious damage to many moso bamboo (Phyllostachys pubescens) forests in China’s Fujian province. The culms of this plant are an essential component of the building and handicraft industries, and the shoots are a prized food item in many Asian countries. Furthermore, bamboo forests play an important soil conservation role in mountainous areas. We examined pest mite outbreaks in several moso bamboo plantations in Fujian, and could show that a change in cultivation style from polyculture (a kind of mixed forest) to monoculture (all plants other than bamboo were removed) was primarily responsible for the local extinction of an important predaceous mite species. This phenomenon is due to the periodic shedding of leaves by the bamboo, which forces the predator mites occurring on bamboo to switch to prey mite species that occur on other plants. We then tried to elucidate the factors that resulted from such a cultivation change. Adopting a computer simulation approach, we could successfully show that at least two plants, moso bamboo and Chinese silvergrass, are necessary to maintain stable predator–prey interactions in moso forests. That is, systems consisting of one common predator and two host-specific pest mites on different host plant species frequently became stable when the pest mites were at low density. This finding indicates clearly that bio-diversity, even when it consists of only two plants and three mite species as in this study, is necessary for the sustainable regulation of large-scale forests, such as moso bamboo plantations.     

Developing joint educational programs in sustainability science across different universities: a case study from Japan

The challenge for sustainability educational programs lies in how to imbue students with the strong motivation necessary to move the world in a more sustainable direction. Five universities in Japan have mutually collaborated in the design and development of a unique curriculum and education system for sustainability science since 2008. Specifically, they have developed a common and remote lecture system called the “Frontier of sustainability science” (FSS). This paper discusses the concepts and challenges of FSS and how it was organized to teach students to actively learn how to work with people of various disciplines to realize interdisciplinarity.     

The use of leeches to monitor aquatic PCB contamination at Mid-Canada radar line site 050: Four years post-remediation

The Mid-Canada Radar Line (MCRL) was built by the Canadian government during the 1950s and closed in the 1960s. MCRL Site 050 located in close proximity to Fort Albany First Nation was a source of polychlorinated biphenyls (PCBs); thus, this site was remediated in 2001. There has been concern in Fort Albany that the Albany River by MCRL Site 050 is still contaminated. We examined whether the aquatic environment surrounding MCRL Site 050 has returned to background levels four years post-remediation using leeches (Haemopis spp.) as bioindicators. Leech data for 2005 indicates that PCB levels remain higher near Site 050 than at the control site upstream; however, there has been a decrease in difference between Site 050 and the control site for leech body burden between years. Thus, the removal of the terrestrial source of PCB contamination at Site 050 appears to have removed the main source of aquatic PCBs.     

Wetland soil and vegetation bismuth content following experimental deposition of bismuth pellets

Bismuth pellets have been approved as a non-toxic alternative to lead pellets in Canada since 1997 but, to our knowledge, there is little literature for soil and vegetation bismuth content in areas of bismuth pellet deposition. The present study addresses this shortcoming by measuring wetland soil and vegetation bismuth content following experimental deposition of bismuth pellets under ambient and experimentally increased acidic deposition conditions. We manipulated 24 plots in a fully factorial design (bismuth shot x soil acidification) in a south-eastern Ontario freshwater wetland during 1999-2003. Soil pH (range 6.5-7.3) increased significantly (p = 0.001) during the experimental period but there were no significant differences amongst treatments (p = 0.79). Significantly (p < 0.05) greater bismuth concentrations were measured in soil receiving bismuth pellets (mean +/- SE, n = 6; with acidification = 2.55 +/- 1.02 microg Bi g(-1) dry mass [DM]; without acidification = 6.40 +/- 2.23 microg Bi g(-1) DM) compared to plots that were not seeded with bismuth pellets (without acidification = 0.42 +/- 0.09 microg Bi g(-1) DM; with acidification = 0.39 +/- 0.10 microg Bi g(-1) DM). Nevertheless, bismuth levels in 20 of 24 aboveground tissue samples from the Carex lacustris-Agrostis scabra community were below detection levels (0.057 microg Bi g(-1) DM); the other samples ranged from 0.065 to 0.095 microg Bi g(-1) DM, similar to global background levels. Primary productivity in plots receiving bismuth pellets and soil acidification was not significantly (p = 0.15) different to vegetation in plots that were not manipulated. The results suggest bismuth mobilization from bismuth pellets into soil but not to aboveground vegetation.     

Lysis of cyanobacteria with volatile organic compounds

One of bacteria collected from Lake Sagami, Japan, Brevibacillus sp., was found to have a lytic activity of cyanobacteria, but did not produce active compounds. Instead, the co-culturing of Microcystis with the Brevibacillus sp. enhanced the production of two volatile compounds, beta-cyclocitral and 3-methyl-1-butanol, and the former had a characteristic lytic activity. It was confirmed that these volatile compounds were derived from the cyanobacteria themselves. beta-Ionone, geosmin and 2-methylisoborneol derived from cyanobacteria and similar volatile compounds, terpenoids, produced by plants also had a lytic activity. The minimum inhibitory concentration values of the cyanobacterial metabolites were estimated to be higher than those of compounds from plants except for a few compounds. Among them, beta-cyclocitral only produced a characteristic color change of culture broth from green to blue. This color change is similar to the phenomenon observed when a sudden decline in growth of cyanobacteria begins in a natural environment.     

Immunologic effects of perinatal exposure to dioxins, PCBs and organochlorine pesticides in Japanese infants

Effects of perinatal exposure to dioxins, PCBs and organochlorine pesticides on lymphocyte subsets were investigated in the peripheral blood from 101 Japanese infants with approximately 10 months of age. Perinatal exposure to these organochlorine compounds were estimated by their contamination levels in the breast milk of the mothers. Lymphocyte subsets such as CD16+, HLA-DR+, CD4+, CD4+8+, CD8+, CD3+ and CD20+ cells in peripheral venous blood were assessed in a subgroup of 92 infants. Greater exposures to HCE, chlordane and dioxins were significantly associated with the increase in the percentages of CD8+ and CD3+ T lymphocytes and CD4+/CD8+ T cell ratios, respectively. In addition, higher HCH exposure was also associated with a decrease in the percentage of HLA-DR+ T lymphocytes. Furthermore effects of dioxins, DDT and PCBs on the percentage of CD16+ T lymphocyte were more pronounced by the combined exposure of dioxins and PCBs or by the combined exposure of DDT and PCBs. Effects of HCE on the percentages of CD8+ T lymphocyte were also more pronounced by the combined exposure of HCE and chlordane. In conclusion, our study suggests that greater exposures to dioxins, PCBs and organochlorine pesticides determined in this study (except dieldrin) influence the immune system of Japanese infant, although the clinical significance of these changes is uncertain.     

Gasification of waste plastics by steam reforming in a fluidized bed

The process of producing synthetic gas from waste plastics by steam reforming was investigated. To evaluate this process, the steam reforming of the oils derived from low-density polyethylene and polystyrene were carried out using a laboratory-scale fluidized bed of Ni-Al₂O₃ catalysts. The performance of gasification in terms of carbon conversion, gas yield, and gas compositions was examined. Although oils derived from plastics contain many kinds of heavy hydrocarbons and aromatics, they were well gasified at temperatures above 1023 K with a steam/carbon ratio of 3.5 and a weight hourly space velocity of 1 h⁻¹. The hydrogen content of the product gas was very high at approximately 72 vol% for polyethylene-derived oil and 68 vol% for polystyrene-derived oil. These compositions agreed well with the values calculated from chemical equilibrium.