Keiichi Arashidani

Measurement of the Physical Properties of Aerosols in a Fullerene Factory for Inhalation Exposure Assessment

Assessment of human exposure is important for the elucidation of potential health risks. However, there is little information available on particle number concentrations and number size distributions, including those of nanoparticles, in the working environments of factories producing engineered nanomaterials. The authors used a scanning mobility particle sizer and an optical particle counter to measure the particle number size distributions of particles ranging in diameter (D p ) from 10 nm to >5000 nm in a fullerene factory and used scanning electron microscopy to examine the morphology of the particles. Comparisons of particle size distributions and morphology during non-work periods, during work periods, during an agitation process, and in the nearby outdoor air were conducted to identify the sources of the particles and to determine their physical properties. A modal diameter of 25 nm was found in the working area during the non-work period; this result was probably influenced by ingress of outdoor air. During the removal of fullerenes from a storage tank for bagging and/or weighing, the particle number concentration at D p <50 nm was no greater than that in the non-work period, but the concentration at D p >1000 nm was greater during the non-work period. When a vacuum cleaner was in use, the particle number concentration at D p <50 nm was greater than that during the non-work period, but the concentration at D p >1000 nm was no greater. Scanning electron microscopy revealed that the coarse particles emitted during bagging and/or weighing were aggregates/agglomerates of fullerenes; although origin of particles with D p <50 nm is unclear.

Effect of prolonged exposure to low concentrations of formaldehyde on the corticotropin releasing hormone neurons in the hypothalamus and adrenocorticotropic hormone cells in the pituitary gland in female mice.

We examine the effect on the hypothalamus-pituitary-adrenal gland (HPA) axis of prolonged exposure to low levels of formaldehyde in female C3H/He mice, using immunocytochemical and RT-PCR methods. Two groups of female mice were exposed to differing concentrations (0, 80, 400, 2000 ppb) of formaldehyde inhalation for 16 h/day, 5 days/week, for 12 weeks. The corticotropin releasing hormone (CRH)-immunoreactive (ir) neurons in the hypothalamus were then examined, together with the adrenocorticotropin hormone (ACTH)-ir cells and ACTH mRNA in the pituitary. One group comprised sham control mice. The other group was made allergic by injection of ovalbumin (OVA) and alum prior to exposure to formaldehyde, since most sick building syndrome (SBS) sufferers are women with allergic disease. These animals were further exposed to aerosolized OVA as a booster four times during the exposure period. Our results showed a dose-dependent increase in the number of CRH-ir neurons in the non-allergy (NAG) group. A similar pattern was found in ACTH-ir cells and ACTH mRNA. The allergy (AG) model group showed an increase in basal levels of all markers of HPA activity. Moreover, the AG mice appeared to respond to the lowest concentration of formaldehyde, and all indices of HPA activity were reduced at the highest concentrations of formaldehyde. These results relate to an important clinical issue and also have implications in the broader area of HPA regulation. We conclude that our experimental system may be a suitable animal model for SBS and/or multiple chemical sensitivity (MCS).

Inhalation of Low-Level Formaldehyde Increases the Bcl-2/Bax Expression Ratio in the Hippocampus of Immunologically Sensitized Mice

Objective: A recent study from our research group showed that repeated exposure to low-level formaldehyde (FA) increases the production of nerve growth factor, involving the survival and maintenance of neurons, in the hippocampus of immunized mice. In the present study, we examined the effects of FA on apoptotic mechanisms regulating survival and death of cells and on N-methyl-D-aspartate (NMDA) receptors related to hippocampal functions in the mouse hippocampus. Methods: Western blot analyses were performed for Bcl-2, Bax and NMDA receptor subtypes 2A and 2B of the hippocampus taken from C3H mice exposed to 0 or 400 ppb of FA with or without ovalbumin (OVA) immunization. Immunohistochemical analysis for active caspase-3 was also carried out for these mice. Results: The ratio of Bcl-2 to Bax expression levels significantly increased with 400-ppb FA exposure in OVA-immunized mice but not in mice without OVA immunization, although differences in each protein level were not significant among groups. Active caspase- 3-immunoreactive cells were found in the hippocampus. However, the number was only a few and not significantly affected by FA exposure and OVA immunization. NMDA receptor type 2A and 2B expression levels of FA-exposed mice were sustained at comparative levels with those for the control mice with or without OVA immunization. Conclusions: These results indicate that changes in the Bcl-2/Bax expression ratio, which occurs with low-level FA exposure and immunization and may follow enhancement of nerve growth factor production, exerts a protective effect against cell death by apoptosis.

Differences in allergic inflammatory responses between urban PM2.5 and fine particle derived from desert-dust in murine lungs.

The biological and chemical natures of materials adsorbed onto fine particulate matter (PM2.5) vary by origin and passage routes. The exacerbating effects of the two samples-urban PM2.5 (U-PM2.5) collected during the hazy weather in a Chinese city and fine particles (ASD-PM2.5) collected during Asian sand dust (ASD) storm event days in Japan-on murine lung eosinophilia were compared to clarify the role of toxic materials in PM2.5. The amounts of β-glucan and mineral components were higher in ASD-PM2.5 than in U-PM2.5. On the other hand, organic chemicals, including polycyclic aromatic hydrocarbons (PAHs), were higher in U-PM2.5 than in ASD-PM2.5. When BALB/c mice were intratracheally instilled with U-PM2.5 and ASD-PM2.5 (total 0.4 mg/mouse) with or without ovalbumin (OVA), various biological effects were observed, including enhancement of eosinophil recruitment induced by OVA in the submucosa of the airway, goblet cell proliferation in the bronchial epithelium, synergic increase of OVA-induced eosinophil-relevant cytokines and a chemokine in bronchoalveolar lavage fluid, and increase of serum OVA-specific IgG1 and IgE. Data demonstrate that U-PM2.5 and ASD-PM2.5 induced allergic inflammatory changes and caused lung pathology. U-PM2.5 and ASD-PM2.5 increased F4/80(+) CD11b(+) cells, indicating that an influx of inflammatory and exudative macrophages in lung tissue had occurred. The ratio of CD206 positive F4/80(+) CD11b(+) cells (M2 macrophages) in lung tissue was higher in the OVA+ASD-PM2.5 treated mice than in the OVA+U-PM2.5 treated mice. These results suggest that the lung eosinophilia exacerbated by both PM2.5 is due to activation of a Th2-associated immune response along with induced M2 macrophages and the exacerbating effect is greater in microbial element (β-glucan)-rich ASD-PM2.5 than in organic chemical-rich U-PM2.5.

Effects of inhaled 1-bromopropane vapor on rat metabolism.

Wistar male rats were exposed to 1-bromopromane (1-BP) vapor for 6 h a day, 5 days a week, for 3 and 4 weeks (1500 ppm) and 1 day, and 4 and 12 weeks (700 ppm). After the exposures, 1-BP and its metabolites were measured temporally. In the samples obtained from the 700 ppm exposures, hematological and biochemical examinations in blood and measurements of hepatic cytochromes P450 were carried out. 1-BP in blood decreased rapidly to the detection limit within 0.7 h. On the other hand, bromine ion persisted longer in both blood and urine; the biological half-life of bromine ion was 4.7-15.0 days in blood and 5.0-7.5 days in urine. Glycidol was detected in the urine samples. Based on the experimental results, the metabolic pathway of 1-BP was discussed. Hepatic cytochromes P450, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in blood decreased significantly with 1-BP exposure, but other enzyme activities did not differ significantly.

Effects of two Asian sand dusts transported from the dust source regions of Inner Mongolia and northeast China on murine lung eosinophilia

The quality and quantity of toxic materials adsorbed onto Asian sand dust (ASD) are different based on dust source regions and passage routes. The aggravating effects of two ASDs (ASD1 and ASD2) transported from the source regions of Inner Mongolia and northeast China on lung eosinophilia were compared to clarify the role of toxic materials in ASD. The ASDs contained different amounts of lipopolysaccharides (LPS) and β-glucan (ASD1ASD2). CD-1 mice were instilled intratracheally with ASD1, ASD2 and/or ovalbumin (OVA) four times at 2-week intervals. ASD1 and ASD2 enhanced eosinophil recruitment induced by OVA in the submucosa of the airway, with goblet cell proliferation in the bronchial epithelium. ASD1 and ASD2 synergistically increased OVA-induced eosinophil-relevant cytokines interleukin-5 (IL-5), IL-13 (ASD1ASD2) in bronchoalveolar lavage fluid. ASD2 aggravating effects on lung eosinophilia were greater than ASD1. The role of LPS and β-glucan in ASD2 on the production of pro-inflammatory mediators was assessed using in vitro bone marrow-derived macrophages (BMDMs) from wild type, Toll-like receptor 2-deficient (TLR2-/-), TLR4-/-, and MyD88-/- mice (on Balb/c background). ASD2-stimulated TLR2-/- BMDMs enhanced IL-6, IL-12, TNF-α, MCP-1 and MIP-1α secretion compared with ASD2-stimulated TLR4-/- BMDMs. Protein expression from ASD2-stimulated MyD88-/- BMDM were very low or undetectable. The in vitro results indicate that lung eosinophilia caused by ASD is TLR4 dependent. Therefore, the aggravation of OVA-related lung eosinophilia by ASD may be dependent on toxic substances derived from microbes, such as LPS, rather than SiO2.

Effect of ethylene glycol monomethyl ether and diethylene glycol monomethyl ether on hepatic metabolizing enzymes

Glycol ethers have been extensively used in industry over the past 40-50 years. Numerous studies on the toxicity of glycol ethers have been performed, however, the effects of glycol ethers on the hepatic drug metabolizing enzymes are still unknown. We studied the changes of the putative metabolic enzymes, that is, the hepatic microsomal mixed function oxidase system and cytosolic alcohol dehydrogenase, by the oral administration of diEGME and EGME. Adult male Wistar rats were used. DiEGME was administered orally; 500, 1000, 2000 mg/kg for 1, 2, 5 or 20 days and EGME was 100, 300 mg/kg for 1, 2, 5 or 20 days. Decreases in liver weights were produced by highest doses of diEGME (2000 mg/kg body wt/day for 20 days) and EGME (300 mg/kg body wt/day for 20 days). DiEGME increased hepatic microsomal protein contents and induced cytochrome P-450, but not cytochrome b5 or NADPH-cytochrome c reductase. The activity of cytosolic ADH was not affected by diEGME administration. On the other hand, EGME did not change cytochrome P-450, cytochrome b5 or NADPH-cytochrome c reductase. The activity of cytosolic ADH was increased by repeated EGME treatment. Therefore it is suspected that the enzyme which takes part in the metabolism of diEGME is different from that of EGME, although diEGME is a structural homologue of EGME.

Simplified analysis of benzo[a]pyrene in airborne particulates by high-performance liquid chromatography

Abstract A simple high-performance liquid chromatographic (HPLC) method for the determination of benzo[a]pyrene (BaP) in airborne particulates is described. The method involves (i) ultrasonic extraction of hydrocarbons, (ii) clean-up of extracted polynuclear aromatic hydrocarbons (PAHs) by basic alumina and (iii) separation and determination of each PAH by HPLC with a fluorescence detector. The recovery of BaP was 99% and the detection limit (signal-to-noise ratio  2) was 16 pg. The results were compared with those obtained by another method used for a nationwide survey in Japan, which consists in ultrasonic extraction of PAHs, separation of the PAHs by one-dimensional dual-band thin-layer chromatography and spectrofluorimetric determination. The results obtained by the two methods were in good agreement (r  0.998) for 20 airborne particulate samples.

Endothelial specific granules in the umbilical veins of the postnatal rabbit

SummaryA remarkable increase in number of endothelial specific granules was observed in the rabbit umbilical veins between 2 and 5 days after birth. Electron microscopy indicated that the granules were segregated in the Golgi complex of the endothelial cells and released into the vascular lumen during the postnatal obliteration stage of this vessel.Incubation of the postnatal vessels in Ringer solution containing a histamine releasing compound induced remarkable morphological alterations of these cytoplasmic components; a reduction of their osmiophilia, swelling with a widened space separating the granular matrix from the limiting membrane, fusion to each other and expulsion of their contents into the vascular lumen, as in mast cell degranulation by this drug, were noted.High-performance liquid chromatography of the homogenized vessels demonstrated appreciable concentrations of histamine in the postnatal samples. There was a correlation between the histamine concentration and the quantity of granules in the respective postnatal samples.The present study strongly suggests that the granules are reservoirs of histamine and have an important role in the obliteration of this vessel.

PM2.5 collected in China causes inflammatory and oxidative stress responses in macrophages through the multiple pathways.

Air pollution continues to increase in East Asia, particularly in China, and is considered to cause serious health problems. In this study, we investigated the toxicological properties of particulate matter ≤2.5mm (PM2.5) collected in an urban area in China (Shenyang), focusing on inflammation and oxidative stress tightly linked to respiratory diseases. Exposure to PM2.5 significantly increased the expression levels of inflammatory (interleukin-1β and cyclooxygenase-2) and oxidative stress (heme oxygenase1) genes in the mouse macrophages. PM2.5-caused inflammatory response was strongly suppressed by endotoxin neutralizer (polymyxin B) and knock-out of toll-like receptor 4, while oxidative stress was not. On the other hand, an antioxidant (N-acetylcystein) suppressed oxidative stress, but not inflammatory response. These results suggest that PM2.5 in the atmospheric environment of China causes inflammation and oxidative stress in macrophages via separate pathways.