Prolonged exposure to low doses of ozone: short- and long-term changes in behavioral performance in mice

Two separate experiments were designed to assess the effects of ozone exposure on outbred CD-1 mice. In the first experiment, adult males were exposed continuously to O3 at 0, 0.3, or 0.6 ppm for 30 days and their behavior was assessed in a 5-min open-field test on exposure days 4 and 19 and on day 3 after the end of the exposure phase. In addition, mice performed a Morris water maze task from exposure day 24 to 28. In the second experiment, adult females were exposed from 30 days prior to the formation of breeding pairs until gestational day 17 to the same doses used in the first experiment. Litters were fostered at birth to untreated dams and neurobehavioral development of the offspring was investigated until adulthood. Specifically, somatic and sensorimotor development [postnatal day (PND) 2-20], homing performance (PND 12), motor activity (PND 21), passive avoidance (PND 22-23), water maze performances (PND 70-74), and response to a nociceptive stimulus (PND 100) were assessed. Results from both experiments confirm that exposure to O3 slightly but selectively affected neurobehavioral performance in rodents. Exposure to O3 did not grossly affect neurobehavioral development, whereas it consistently impaired reversal learning in the Morris water maze test in both prenatally and adult exposed mice. Moreover, longer latency to step-through in the first trial of the passive avoidance test and a decrease in wall rearing in the hot-plate test were recorded in O3 prenatally exposed mice. Except for the first open-field test, altered responses were observed only in animals exposed at the intermediate concentration of the gas. Adaptation and/or onset of compensatory mechanisms might be responsible for the lack of linear dose-response relationships.     

Clearance and dimensional changes of crocidolite asbestos fibers isolated from lungs of rats following short-term exposure

Previous studies in this laboratory have demonstrated fiber clearance and dimensional changes in chrysotile asbestos using a rat inhalational model of short-term exposure. The purpose of the present study was to determine whether or not similar changes occurred in crocidolite asbestos fibers isolated from the lungs of rats at various intervals after termination of exposure. Fibers were recovered on a membrane filter using a sodium hypochlorite digestion-concentration technique, and the numbers and dimensions of the fibers assessed using scanning electron microscopy. The mass of crocidolite asbestos retained in the lung was then calculated. Of the respirable fraction, 19% was deposited in the lungs, and 25% of this amount was still present 1 month after exposure. These values are similar to the 23% deposition and 19% retention rates for chrysotile determined in our previous study. There was a progressive increase in mean fiber length with time postexposure (P less than 0.05), but no significant changes in the diameter of the population of crocidolite fibers retained in the lung. Thus it appears that the tendency for longer fibers to be retained within lung tissue is a characteristic shared by serpentine and amphibole asbestos fibers, whereas longitudinal splitting with progressive decrease in mean fiber diameter in vivo occurs primarily with the serpentine fibers.     

Influenza virus-induced alterations of cytochrome P-450 enzyme activities following exposure of mice to coal and diesel particulates

We have investigated a relationship between two detoxication systems, metabolic detoxication through the cytochrome P-450 (P-450) pathway and resistance to infection through interferon (IFN), in mice infected with influenza virus following exposure to coal dust (CD) and diesel exhaust (DE) particulates. Mice were exposed by inhalation to filtered air (FA; control), CD, or DE for 1 month and then inoculated intranasally (IN) with influenza virus. During infection, 7-ethoxycoumarin deethylase (7ECdeEt'ase) and ethylmorphine demethylase (EMdeMe'ase) (monooxygenases), and NADPH cytochrome c reductase (NADPH c red'ase) were measured in liver microsomes. Temporal patterns of enzyme activities were observed with control animals. EMdeMe'ase and NADPH c red'ase exhibited peak values at Day 4 postinfection (27.6 and 482 nmole/min/mg protein, respectively), compared to initial activities (9.1 and 307 nmole/min/mg protein, respectively). 7ECdeEt'ase activity decreased between Days 1-3 postvirus infection and thereafter returned to the original value (1.7 nmole/min/mg protein). When the mice were first exposed to CD or DE particulates for 1 month prior to influenza infection, changes in enzyme temporal patterns were observed. The increased EMdeMe'ase activity at Day 4 was not observed in mice exposed to CD and was reduced in mice exposed to DE. Preexposure to either particulate resulted in the abolition of the increased Day 4 activity of NADPH c red'ase. The 7ECdeEt'ase postinfection temporal pattern was not affected by a preexposure to either particulate. Estimates of the enzyme activities after the 1-month exposure to FA, CD, or DE but before virus infection indicated no changes due to particulate exposure alone. Under these conditions of particulate exposure and virus infection, serum IFN levels in the mice used in this study peaked at Days 4-5 and were unaffected by the 1-month preexposure to CD or DE (Hahon et al., (1985). The data suggest the relationship that exists between metabolic detoxication and resistance to infection in normal mice was altered during a short-term preexposure to CD or DE.     

Hyperplastic changes in the rat distal tubular epithelial cells following in utero exposure to methylmercury

Female Sprague—Dawley rats were injected with 1.0 mg methylmercury chloride on the eighth day of pregnancy. Tissues from the renal cortex of the offsprings were sampled for electron microscopy. Besides degenerative changes in the proximal convoluted tubules, hyperplastic changes were observed in the distal convoluted tubules. Increased mitotic index was found in many distal tubular epithelial cells. Hyperplastic thickening of these tubular linings was also observed. Such hyperplastic changes may be suggestive of premalignant changes.     

Tropospheric ozone: the dynamics of human exposure

The conditions in the ambient atmosphere conducive to ozone exposure are examined, and placed into a context of the time and locations where individuals would be expected to be affected by high ozone. This is done for both 1 h and 8 h averaging times. Concentrations of ozone in the ambient atmosphere can violate the National Ambient Air Quality Standard (NAAQS) and also the Time Weighted Average-Threshold Limit Value (TWA-TLV) for workers. Exposures that occurred in a 1982 episode associated with a health effects study are described in detail. The effective dose received by a camper at a children's summer camp appeared to be similar to that delivered to volunteers during a controlled human exposure study in which effects on pulmonary function were observed.     

乙双吗啉处理小鼠白细胞DNA-加合物水平变化的研究

目的研究乙双吗啉处理小鼠白细胞DNA-加合物水平的变化规律。方法整体动物实验:①整体动物实验方法:纯系615小鼠80只随机分为乙双吗啉1、2和4mg剂量处理组及对照组,处理组给予相应剂量乙双吗啉灌胃,每日1次,连续2个月,对照组同时给予等量蒸馏水,观察处理不同时间小鼠外周血象及骨髓象的变化;②外周血白细胞DNA的提取及定量;③DNA-加合物的测定;④外周血白细胞微核率的测定和骨髓染色体畸变率测定。离体实验方法:①离体实验体系的建立;②外周血白细胞DNA的提取及定量;③DNA-加合物测定。结果①整体动物实验:乙双吗啉处理小鼠白血病发病率明显增高,其发病率分别为:1mg组15%,2mg组25%,4mg组25%,与对照组相比差异有非常显著性(P<0.01),处理组白血病小鼠总体发病率为21.7%;乙双吗啉处理小鼠外周血白细胞DNA-加合物较对照组升高(P<0.01);乙双吗啉处理小鼠外周血白细胞微核率和骨髓染色体畸变率较对照组升高(P<0.01);②离体实验:乙双吗啉可使小鼠白细胞DNA-加合物升高,与对照组比差异有非常显著性(P<0.01)。结论乙双吗啉可诱发小鼠白细胞DNA-加合物水平升高。     

Anxiety in mice following acute aspartame and ethanol exposure.

The purpose of the present study was to look at the effect of aspartame on the anxiolytic actions of ethanol. Previous research has shown that ethanol reliably produces an anxiolytic effect on rodent's plus-maze performance. There have been anecdotal reports that aspartame increases anxiety. CD-1 male mice were given i.p. aspartame doses of vehicle, 1000, or 2000 mg/kg, followed 30 min later by i.p. ethanol doses of 1.6 g/kg or vehicle. Animals were then placed in an open field, then tested in the plus-maze. Results determined that the aspartame condition had no significant effect on anxiety-related behavior, nor did it alter the anxiolytic actions of ethanol. Thus, acute high dose exposure to aspartame does not appear to affect anxiety-related behaviors.     

Vitamin B-12-deficiency affects immunoglobulin production and cytokine levels in mice

To clarify the role of B-12 in the immunological function, serum C3, IgM, IgG, IgE contents, splenocytes expression of CD4, CD8, and CD4 positive intracellular IFN-gamma and IL-4 were examined in B-12-deficient mice, and the effect of the administration of CH3-B-12 was also studied. Serum C3, IgM and IgG contents were lower in B-12-deficient mice than in the control mice. On the other hand, serum IgE content was significantly higher in B-12-deficient mice, and the value in CH3-B-12 administered mice, administered CH3-B-12 to B-12-deficient mice for 48 h before the end of feeding period, showed a tendency to recovery. CD4+CD8- cells and CD4+CD8-/CD4-CD8+ ratio in splenocytes were significantly higher in B-12-deficient mice than in control mice. CD4+IFN-gamma+ cells was significantly lower in B-12-deficient mice than in control mice, and CD4+IL-4+ was significantly higher in B-12-deficient mice than in control mice. These results suggest that B-12-deficiency causes CD4+CD8-T cells shift from the T helper type 1 to the T helper type 2, which participate in the IgE production and elevates CD4+CD8-/CD4-CD8+ ratio. Thus, B-12 plays a role in maintaining the immune function in mice.     

二氧化硫对小鼠肺及血清中细胞因子的影响

目的　探讨吸入不同浓度SO2 引起小鼠肺组织及血清中抗炎及致炎因子的变化规律 ,进一步阐明SO2致炎作用机制。方法　采用酶联免疫吸附法 (ELISA)分别检测小鼠肺组织及血清中肿瘤坏死因子 (TNF -α)、白介素- 6 (IL - 6 )、转化生长因子 - β1(TGF - β1)的含量。 结果　 ( 1)肺组织 :当SO2 吸入浓度为 14mg/m3 时 ,肺组织中IL- 6、TNF -α的含量均显著升高 (P <0 0 5 ) ,而TGF - β1没有明显变化 ;吸入 2 8mg/m3 SO2 后 ,肺组织中IL - 6、TNF-α均显著升高 (分别为P <0 0 1,P <0 0 5 ) ,TGF - β1的升高不明显 ;吸入5 6mg/m3 SO2 之后 ,肺组织中 3种细胞因子均未见显著改变。 ( 2 )血清 :只有TNF -α在SO2 吸入浓度为 14mg/m3 时显著升高 ,其余实验小鼠的血清中 3种细胞因子均无显著改变。 ( 3)吸入SO2 后导致肺部致炎因子浓度升高且有明显的剂量 -效应关系 ,而抗炎因子浓度无显著改变。 ( 4 )血清中只有TNF -α在SO2 吸入浓度为 14mg/m3 时显著升高。结果表明 ,SO2 的致炎作用主要发生在肺组织 ,且与这些细胞因子有关。结论　测定肺组织细胞因子对于了解SO2 的肺损伤作用可能比血清更有价值     

Degenerative changes in the neonatal kidney following in-utero exposure to methylmercury

Pregnant Sprague—Dawley rats were injected with 4.0 mg Hg/kg body weight of methylmercuric chloride on the 8th day of pregnancy. Tissue samples from the kidneys of the offspring were obtained for electron microscopic examination. Degenerative changes in the epithelial cells of the proximal convoluted tubules (PCT) including accumulation of lysosomes, enlargement of the apical vacuoles, cytoplasmic vacuolation, and extrusion of large cellular casts into the tubular lumen were observed. Flattening of the basal infolding was found in some PCT epithelial cells. Deposition of basal filaments in these cells were also observed. Extrusion and embedding the spherical microparticles into the basement membranes of the PCT was also a prominent finding. No degenerative changes were seen in the distal tubules. However, degeneration of the Bowman's capsule of the glomeruli, fusion of the epithelial foot-processes, and detachment of the glomerular epithelial cells from their basement membranes could be observed occasionally.     

Wheat flour exposure results in recruitment of inflammatory cells in the lungs of healthy individuals

BACKGROUND: Flour dust in bakeries is known to cause allergic as well as nonallergic respiratory symptoms. Fungal alpha-amylase is a commonly used baking additive that has been shown to have allergenic properties. The aim of this study was to investigate any effects on bronchoalveolar lavage (BAL) cells and peripheral blood lymphocytes (PBL) of healthy individuals exposed to airborne wheat flour dust with or without fungal alpha-amylase added. METHODS: Fifteen subjects were exposed during 1 hr in an exposure chamber, ten individuals to wheat flour alone and five with alpha-amylase added. BAL was performed 2-6 weeks before and 1 day after the exposure. BAL cells were differentially counted and flowcytometric analysis of the expression of activation, adhesion, and subset markers on alveolar macrophages (AM) and T cells in BAL fluid and peripheral blood were carried out. RESULTS: Exposure to wheat flour dust increased the total number of cells in BAL fluid from 75.4 (i.q. range 70.4-104.1) to 127.4 (92.1-187.4) cells x 10(6)/L, P < 0.01. There was a significant difference in the change of total BAL cell concentration between the study group exposed to wheat flour only (n = 10; increase with 91.9 x 10(6)/L) and the group exposed to wheat flour with the baking additive fungal alpha-amylase (n = 5; decrease with 5.4 x 10(6)/L). The exposure level of respirable dust was lower in the group that received alpha-amylase and the increase in BAL cell concentration showed a positive correlation with the concentration of respirable dust in the exposure chamber (r = 0.80, P < 0.001). The phenotypic analysis of AM indicated an influx of monocytic cells. CONCLUSIONS: The results indicate that the concentration of respirable dust, but not alpha-amylase, is of importance for the recruitment of inflammatory cells to the peripheral airways in healthy individuals exposed to wheat flour dust.     

Mixed mold mycotoxicosis: immunological changes in humans following exposure in water-damaged buildings

The study described was part of a larger multicenter investigation of patients with multiple health complaints attributable to confirmed exposure to mixed-molds infestation in water-damaged buildings. The authors present data on symptoms; clinical chemistries; abnormalities in pulmonary function; alterations in T, B, and natural killer (NK) cells; the presence of autoantibodies (i.e., antinuclear autoantibodies [ANA], autoantibodies against smooth muscle [ASM], and autoantibodies against central nervous system [CNS] and peripheral nervous system [PNS] myelins). A total of 209 adults, 42.7 +/- 16 yr of age (mean +/- standard deviation), were examined and tested with (a) self-administered weighted health history and symptom questionnaires; (b) standardized physical examinations; (c) complete blood counts and blood and urine chemistries; (d) urine and fecal cultures; (e) thyroid function tests (T4, free T3); (f) pulmonary function tests (forced vital capacity [FVC], forced expiratory volume in 1 sec [FEV1.0], and forced expiratory flow at 25%, 50%, 75%, and 25-75% of FVC [FEF25, FEF50, FEF75, and FEF2(25-75)]); (g) peripheral lymphocyte phenotypes (T, B, and NK cells) and mitogenesis determinations; and (h) a 13-item autoimmune panel. The molds-exposed patients reported a greater frequency and intensity of symptoms, particularly neurological and inflammatory symptoms, when compared with controls. The percentages of exposed individuals with increased lymphocyte phenotypes were: B cells (CD20+), 75.6%; CD5+CD25+, 68.9%; CD3+CD26+, 91.2%; CD8+HLR-DR+, 62%; and CD8+CD38+, 56.6%; whereas other phenotypes were decreased: CD8+CD11b+, 15.6% and CD3-CD16+CD56+, 38.5%. Mitogenesis to phytohemagglutinin was decreased in 26.2% of the exposed patients, but only 5.9% had decreased response to concanavalin A. Abnormally high levels of ANA, ASM, and CNS myelin (immunoglobulins [Ig]G, IgM, IgA) and PNS myelin (IgG, IgM, IgA) were found; odds ratios for each were significant at 95% confidence intervals, showing an increased risk for autoimmunity. The authors conclude that exposure to mixed molds and their associated mycotoxins in water-damaged buildings leads to multiple health problems involving the CNS and the immune system, in addition to pulmonary effects and allergies. Mold exposure also initiates inflammatory processes. The authors propose the term "mixed mold mycotoxicosis" for the multisystem illness observed in these patients.     

Fish oil feeding delays influenza virus clearance and impairs production of interferon-gamma and virus-specific immunoglobulin A in the lungs of mice

Ingestion of fish oil can suppress the inflammatory response to injury and may impair host resistance to infection. To investigate the effect of a diet containing fish oil on immunity to viral infection, 148 BALB/c mice were fed diets containing 3 g/100 g of sunflower oil with either 17 g/100 g of fish oil or beef tallow for 14 d before intranasal challenge with live influenza virus. At d 1 and d 5 after infection, the mice fed fish oil had higher lung viral load and lower body weight (P < 0.05). In addition to the greater viral load and weight loss at d 5 after infection, the fish oil group consumed less food (P < 0.05) while the beef tallow group was clearing the virus, had regained their preinfection weights and was returning to their preinfection food consumption. The fish oil group had impaired production of lung interferon-gamma (IFN-gamma), serum immunoglobulin (Ig) G and lung IgA-specific antibodies (all P < 0. 05) although lung IFN-alpha/beta and the relative proportions of bronchial lymph node CD4+ and CD8+ T lymphocytes did not differ between groups after infection. The present study demonstrates a delay in virus clearance in mice fed fish oil associated with reduced IFN-gamma and antibody production and a greater weight loss and suppression of appetite following influenza virus infection. However, differences observed during the course of infection did not affect the ultimate outcome as both groups cleared the virus and returned to preinfection food consumption and body weight by d 7.     

Ultrastructural changes in the rat kidney following fetal exposure to ethanol.

Previous studies have implicated renal ultrastructural abnormalities in the pathogenesis of tubular dysfunction in fetal alcohol syndrome. Scanning electron microscopic studies were performed to examine the role of glomerular and tubular structural changes in this syndrome. Pregnant Sprague-Dawley rats were fed a liquid diet in which ethanol constituted 35% of the total caloric content or pair-fed an isocaloric control diet from gestational day 8 to the day of birth. After delivery, offspring were housed with the dam and left undisturbed until 18 days of age when they were weaned and given free access to standard chow diet and water. At random, kidneys from 11 offspring of ethanol-fed (E) rats and 7 pair-fed control (C) rats were fixed by in vivo retrograde perfusion at 90 days of age for ultrastructural studies. The E rats showed cytoplasmic mitochondrial atrophy and vacuolar structures of the epithelial cells of the distal tubules and collecting ducts not seen in C rats. No obvious difference was found in the glomerular, proximal tubule, or loop of Henle architecture between the two groups. These findings suggest that rats prenatally exposed to ethanol have renal ultrastructural abnormalities that may be important in the genesis of functional disturbances.     

Effects of nitrogen dioxide on red blood cells of rats: alterations of cell membrane components and populational changes of red blood cells during in vivo exposure to NO2

Male Wistar rats were exposed to 4 ppm NO2 for 10 days in order to examine the relationship between the changes in components of red cell membranes and alterations of erythrocyte population. Na+, K+-ATPase activity of red blood cell membranes of exposed animals showed a significantly higher value than that of the control at the first and fourth days of exposure and then decreased to under the control value at the seventh day. In order to examine changes in erythrocyte population, red blood cells were fractionated into four fractions according to their density using Dextran density centrifugation. The alteration of the percentage of lowest-density cells (fraction IV) of exposed animals was completely consistent with that of Na+,K+-ATPase activity in addition to that of the sialic acid content as described in a previous report (K. Kaya, T. Miura, and K. Kubota (1980). Environ. Res. 23, 397-409.). The percentage of fraction IV was 1.43- (P less than 0.05) and 1.68-fold (P less than 0.01) those of the control at the first and fourth days of exposure, respectively, and then decreased to under the control value at the seventh day. This decrease accompanied increases in the percentages of higher-density cells (fractions I and II). Examination of subfractions of red blood cells showed that Na+,K+-ATPase activity and the sialic acid content of three fractions with lower densities have higher values in exposed animals than in the control 1 day after exposure to NO2. Based on these results, it is concluded that increases in Na+,K+-ATPase activity and the sialic acid content occurring 1 day after exposure to 4 ppm NO2 were caused by elevated levels of these components in three fractions with lower densities as well as by an increase in the percentage of lowest-density cells in the erythrocyte population. It was also suggested that NO2 inhalation accelerated aging of erythrocytes with respect to density. The change in Ca2+,Mg2+-ATPase activity, in addition to that in the hexose content as described in a previous report (Kaya et al., 1980), was different from those in the sialic acid content and Na+,K+-ATPase activity. Ca2+,Mg2+-ATPase activity and the hexose content of exposed animals showed slightly reduced values 1 day after exposure to NO2. In all subfractions of red blood cells these values were slightly lower in exposed animals than in the controls. Therefore, reduction in Ca2+,Mg2+-ATPase activity and the hexose content is not due to changes in erythrocyte population.