Biopersistence of inhaled MWCNT in rat lungs in a 4-week well-characterized exposure

It is important to conduct a risk assessment that includes hazard assessment and exposure assessment for the safe production and handling of newly developed nanomaterials. We conducted an inhalation study of a multi-wall carbon nanotube (MWCNT) as a hazard assessment. Male Wistar rats were exposed to well-dispersed MWCNT for 4 weeks by whole body inhalation. The exposure concentration in the chamber was 0.37?±?0.18?mg/m³. About 70% of the MWCNTs in the chamber were single fiber. The geometric mean diameter (geometric standard deviation, GSD) and geometric mean length (GSD) of the aerosolized MWCNTs in the chamber were 63?nm (1.5) and 1.1 μm (2.7), respectively. The amounts of MWCNT deposited in the rat lungs were determined by the X-ray diffraction method and elemental carbon analysis. The average deposited amounts at 3 days after the inhalation were 68 μg/lung by the X-ray diffraction method and 76 μg/lung by elemental carbon analysis. The calculated deposition fractions were 18% and 20% in each analysis. The amount of retained MWCNT in the lungs until 3 months after the inhalation decreased exponentially and the calculated biological half times of MWCNT were 51 days and 54 days, respectively. The clearance was not delayed, but a slight increase in lung weight at 3 days after the inhalation was observed.     

Exposure-response relationship of bronchial mucociliary clearance in rabbits following acute inhalations of sulfuric acid mist

Eight rabbits underwent 1 h oral inhalations of submicrometer sulfuric acid mist at concentrations ranging from approx. 100-1084 micrograms/m3, followed by measurement of the mucociliary clearance of a tracer aerosol from the bronchial tree. These data, plus those from a previous study, were used to construct an exposure concentration-response relationship for alterations in clearance produced by H2SO4. The response pattern is characterized by transient acceleration of clearance at low concentration exposures, and retardation at higher concentrations. In addition, comparison of these results with those from a similar study using human volunteers supports use of the rabbit as an appropriate model for studying mucociliary clearance alterations produced by inhaled irritants.     

Ninety-day toxicity of photomirex in the male rat.

Photomirex (8-monohydromirex) is a demonstrated environmental contaminant and was observed in previous short-term studies to produce lesions in the liver, thyroid and testes of male rats. The present study was undertaken to confirm those observations and to determine the effects after a longer period of exposure. Male rats were fed photomirex for 13 weeks at levels of 0.20, 1.0, 5.0, 25 and 125 ppm in the diet. Deaths were observed in animals receiving the highest dose. Decreased body weight gain and food intake were also observed in that group. Liver weights were increased at 5.0 ppm photomirex and higher. Photomirex caused changes in several biochemical parameters including serum sorbitol dehydrogenase and hepatic aniline hydroxylase activities. Dose-related histological abnormalities were observed in the thyroid and liver starting at the lowest dose level. These results confirm earlier findings and show that photomirex is a potent hepato- and thyrotoxin.     

Effect of parenteral cadmium on zinc in the liver and duodenum

The present work was performed to determine if the increased Zn in the liver of Cd-treated rats was related to the low-molecular-weight Zn-binding factor in the duodenal epithelium. The endogenous Zn increased significantly in the liver 24 h after the subcutaneous injection of Cd (1 $\text{mg}\text{kg}$ body weight). In the Zn group (only Zn given orally) and in the Cd + Zn group (administration of Zn to rats previously injected with Cd), the proportion of Zn associated with the low-molecular weight (MW) Zn-binding factor was 27% and 33%, respectively. This indicates that this binding factor was not influenced markedly by the injection of Cd.     

Toxicological effects of arsenate exposure on hematological,biochemical and liver transaminases activity in an Indian major carp, Catla catla

The impact of acute and sublethal toxicity of arsenate on hematological, biochemical and enzymological parameters of an Indian major carp Catla catla were estimated. The median lethal concentration of sodium arsenate to the fish Catla catla for 96 h was found to be 43.78 mg/L. During acute treatment (43.78 mg/L), hemoglobin (Hb), hematocrit (Ht), red blood cell count (RBC), white blood cell count (WBC), plasma glucose, plasma protein, liver aspartate and alanine aminotransferase (AST and ALT) levels decreased, whereas corpuscular indices like mean cell volume (MCV), mean cell hemoglobin (MCH) and mean cell hemoglobin concentration (MCHC) increased in arsenate treated fish. In sublethal treatment (4.378 mg/L), Hb, Ht, RBC, plasma protein levels decreased while MCHC and plasma glucose levels increased throughout the exposure period. A biphasic trend was noticed in WBC, MCV, MCH, liver AST and ALT levels. The alterations of these parameters can be effectively used as a rapid method to assess health of fish exposed to arsenate in the aquatic environment.     

Influence of essential onion oil on tin and chromium dissolution from tinplate

During food and beverage packaging in tinplate cans the dissolution of tin and chromium into food content may occur. To protect metallic surface different corrosion inhibitors are recommended, nowadays particularly a new group of natural products is of interest. In this work the influence of essential onion oil (EOO) on metals dissolution (tin and chromium) from tinplate sheets before food canning was investigated. The analyses were performed by galvanostatic method and atomic absorption spectroscopy. The values of tin obtained for the internal surface of tinplate covered with EOO (7.31–9.76 g m⁻²) are lower than the values when dioctyl sebacate oil (DOS), as a protective tinplate surface layer for food caning, was used (9.24–11.03 g m⁻²). Obviously, the presence of EOO diminished more efficiently then DOS oil the dissolution of tin in electrolyte during galvanostatic analyses. The efficiency of EOO as corrosion inhibitor was even more pronounced in the case of chromium where the dissolution from 1.8–2.5 mg m⁻² (DOS oil) was lowered to 1.0–1.3 mg m⁻² (EOO). Correlation of results obtained with two different physico-chemical methods was satisfying.     

In vivo and in vitro effect of chelating agents on drug metabolizing enzymes of the rat

Rats given calcium disodium ethylenediaminetetraacetic acid (CaNa₂EDTA), diethylenetriaminepentaacetic acid (DTPA), dimercaprol, p-aminosalicylic acid (PAS), or d-penicillamine (penicillamine) i.p. for 7 successive days showed a significant decrease in the activity of hepatic microsomal benzphetamine N-demethylase. There was no appreciable change in the microsomal cytochrome P-450 concentration. In vitro incubation of the chelating drugs with liver microsomes isolated from rats pre-treated with phenobarbital caused no significant loss of the hemoprotein. The decreased rate of benzphetamine metabolism in microsomal preparations from rats, pretreated with the chelating drugs, may be attributed partly to hepatic depletion of essential trace elements by the chelating drugs.     

Effects of phosphorus supplied in soil on subcellular distribution and chemical forms of cadmium in two Chinese flowering cabbage (Brassica parachinensis L.) cultivars differing in cadmium accumulation

Differences in the subcellular distribution and chemical speciation of Cd between two Chinese flowering cabbage (Brassica parachinensis L.) cultivars, Lubao70 (LB70, low-Cd cultivar) and ChixinNO.4 (CX4, high-Cd cultivar) were investigated under various soil Cd and P treatments. Subcellular fractionation of Cd-containing tissues showed that a higher proportion of Cd was bound to the cell wall fraction of LB70 than that of CX4, indicating that Cd compartment functioned better in LB70. Compared to CX4, LB70 had lower proportions of Cd in inorganic form and water-soluble form, but higher proportions of Cd in proteins/pectates integrated form, implying that the low Cd accumulation in LB70 is associated with the low in vivo mobility of Cd. In both cultivars, shoot and root Cd concentration and translocation of Cd from the roots to the shoots obviously decreased with increasing soil P level. It was found that phosphorus (P) played important roles in Cd uptake and translocation via the processes involved in bonding Cd to the cell wall fraction and forming Cd-phosphate complexes. It is suggested that use of low-Cd cultivars in conjunction with P supply is a much useful way to reduce the pollution risk of Cd in the food chain.     

克拉霉素对哮喘大鼠肺组织血红素氧合酶-1的调控

目的:研究哮喘大鼠肺组织中血红素氧合酶-1(HO-1)的表达情况及克拉霉素对HO-1的调控作用;观察其HO-1表达与BALF中EOS占细胞总数的百分比(EOS%)、嗜酸性粒细胞(EOS)、全血COHb的百分比含量之间的相关性。方法:清洁级雄性SD大鼠30只,随机分为正常对照组(N组)、哮喘组(A组)、克拉霉素治疗组(C组),每组10只。测定全血COHb的百分比含量;计数BALF沉渣中细胞总数和分类;计数肺组织中浸润的炎性细胞数;免疫组织化学染色法观察HO-1在哮喘大鼠肺组织的表达。结果:HO-1主要表达在气道上皮细胞,三组HO-1阳性表达的平均吸光度分别为0.07±0.01、0.22±0.03、0.14±0.02。A组HO-1表达水平显著高于N组(P<0.001),C组HO-1蛋白的表达显著低于A组(P<0.01)。HO-1表达水平与全血COHb的百分比含量、BALF中EOS占细胞总数的百分比及肺组织中EOS总数均呈显著正相关(分别为r=0.887,P<0.01;r=0.889,P<0.01;r=0.883,P<0.01)。结论:哮喘大鼠的肺组织HO-1表达水平显著增加,提示HO-1可能参与哮喘发病过程。克拉霉素明显改善哮喘的气道炎症浸润,其作用机制部分是通过抑制HO-1起作用。     

Dose-based duration adjustments for the effects of inhaled trichloroethylene on rat visual function.

Risk assessments often must consider exposures that vary over time or for which the exposure duration of concern differs from the available data, and a variety of extrapolation procedures have been devised accordingly. The present experiments explore the relationship(s) between exposure concentration (C) and time (t) to investigate procedures for assessing the risks of short-term solvent exposures. The first hypothesis tested was that the product of C x t would produce a constant health effect (Haber's rule). The second hypothesis tested was that exposure conditions produce effects in proportion to the tissue concentrations created. Awake, adult, male Long-Evans (LE) rats were exposed to trichloroethylene (TCE) vapor in a head-only exposure chamber while pattern onset/offset visual evoked potentials (VEPs) were recorded. Exposure conditions were designed to provide C x t products of 0 ppm/h (0 ppm for 4 h) or 4000 ppm/h created through four exposure scenarios: 1000 ppm for 4 h; 2000 ppm for 2 h; 3000 ppm for 1.3 h; or 4000 ppm for 1h (n = 9-10/concentration). The amplitude of the VEP frequency double component (F2) was decreased significantly by exposure; this decrease was related to C but not to t or to the C x t product, indicating that Haber's rule did not hold. The mean amplitude (+/- SEM in muV) of the F2 component in the control and treatment groups measured 4.4 +/- 0.5 (0 ppm/4 h), 3.1 +/- 0.5 (1000 ppm/4 h), 3.1 +/- 0.4 (2000 ppm/2 h), 2.3 +/- 0.3 (3000 ppm/1.3 h), and 1.9 +/- 0.4 (4000 ppm/1 h). A physiologically based pharmacokinetic (PBPK) model was used to estimate the concentrations of TCE in the brain achieved during each exposure condition. The F2 amplitude of the VEP decreased monotonically as a function of the estimated peak brain concentration but was not related to the area under the curve (AUC) of the brain TCE concentration. In comparison to estimates from the PBPK model, extrapolations based on Haber's rule yielded approximately a 6-fold error in estimated exposure duration when extrapolating across only a 4-fold change in exposure concentration. These results indicate that the use of a linear form of Haber's rule will not predict accurately the risks of acute exposure to TCE, nor will an estimate of AUC of brain TCE. However, an estimate of the brain TCE concentration at the time of VEP testing predicted the effects of TCE across exposure concentrations and durations.     

Differential inhibitory effects of the arachidonic acid analog ETYA on rat mast cell exocytosis evoked by secretagogues utilizing cellular or extracellular calcium

ETYA (5,8,11,14-eicosatetraynoic acid; 50-100 microM), which inhibits both cyclo-oxygenase and lipoxidase, inhibited histamine release evoked by secretagogues dependent on extracellular calcium (antigen, dextran, and concanavalin A) but failed to inhibit secretion elicited by secretagogues capable of mobilizing calcium from intracellular sites (48/80, polymyxin B, protamine sulfate and poly-L-lysine). Responses to these latter secretagogues were inhibited only by higher concentrations of ETYA (100-200 microM) that were cytotoxic. Secretion evoked by the calcium ionophore A23187 (0.1 microgram/ml) was inhibited at much lower concentrations of ETYA (1-10 microM) but this inhibition could not be overcome by increasing the concentration of calcium. Responses to higher concentrations of ionophore were not inhibited by ETYA except in amounts affecting cell viability. Like ETYA, each of several fatty acids, including arachidonic acid, were inhibitory towards histamine release evoked by A23187 or 48/80. The results indicate that EYTA acts at some early stage of stimulus-secretion coupling rather than on the final, common, calcium-activated steps of exocytosis. Moreover, this action may be unrelated to inhibition of lipoxidase or cyclooxygenase.     

Effect of metal chelating agents on the storage of norepinephrine in vitro by cerebral synaptic vesicles

The inhibitory effects of fourteen different metal chelating agents on the storage in vitro of [³H]dl-norepinephrine (NE) by the isolated synaptic vesicles from rat brain were investigated with a view to explore the possible importance of metal chelation phenomena. The chelators under examination belong to the classes of polyamines, aminocarboxylic and hydroxy carboxylic acids exhibiting a wide range of metal-binding strengths. Values of ic₅₀, viz., the amount of the chelator which will inhibit 50 per cent of the storage of [³H]dl-NE, were determined for the different compounds. The strengths of chelate formation of the “synaptosomal and vesicular metal ions”, viz. Cu²⁺, Fe²⁺, Fe³⁺, Zn²⁺, Mg²⁺ and Ca²⁺, with the above compounds were compared with their inhibition in vitro of the vesicular storage of [³H]dl-NE in order to determine if a correlation existed between the two. On the basis of regression analyses of the data on the stabilities of the individual metal chelates (log K_ML) and the inhibitory effects of the different chelators (log ic₅₀/NE), significant correlation coefficients were obtained with the Cu²⁺ and Zn²⁺ amine systems, i.e. 0.98 with P < 0.02, and 0.88 with P < 0.02 respectively. In regard to the metal-aminoacids systems, Mg²⁺ gave the most satisfactory correlation coefficient, i.e. 0.91, P < 0.01; with Fe(II) = 0.84, P < 0.02 and the mixed-metal system Cu + Zn + Fe + Mg + Ca = 0.87, P < 0.05. The existence of such correlation is considered significant from the point of view of the metal coordination hypothesis for the vesicular binding and storage of NE.     

Protective effects of Celecoxib on lung injury and red blood cells modification induced by carrageenan in the rat

In the present study, we evaluated the effect of Celecoxib, a selective COX-2 inhibitor, in an acute model of lung injury induced by carrageenan administration in the rats. Injection of carrageenan into the pleural cavity of rats elicited an acute inflammatory response characterized by: fluid accumulation in the pleural cavity which contained a large number of polymorphonuclear neutrophils (PMNs) as well as an infiltration of PMNs in lung tissues and subsequent lipid peroxidation, and increased production of prostaglandin E(2) (PGE(2)), tumor necrosis factor alpha (TNFalpha), and interleukin-1beta. All parameters of inflammation were attenuated by Celecoxib. Furthermore, carrageenan induced an upregulation of the adhesion molecules ICAM-1 and P-selectin, as well as nitrotyrosine and poly(ADP-ribose) synthetase (PARS) as determined by immunohistochemical analysis of lung tissues. The degree of staining for the ICAM-1, P-selectin, nitrotyrosine and PARS was reduced by Celecoxib. These results clearly confirmed that COX-2 plays a critical role in the development of the inflammatory response by altering key components of the inflammatory cascade. Therefore, selective inhibitor of COX-2 such as Celecoxib, offers a therapeutic approach for the management of various inflammatory diseases.     

甘草酸对大鼠胰腺纤维化的干预作用及其机制

目的　观察甘草酸对大鼠实验性胰腺纤维化的干预作用及其可能机制。方法　♂SD大鼠 ,应用胆胰管内注射2 %三硝基苯磺酸 (TNBS)诱导胰腺纤维化 ,甘草酸干预组(n =10 )在制模后 3d尾静脉注射甘草酸 ,剂量为 8mg·kg- 1体重 ,每天 1次 ,持续 4wk ,同时设立对照组 (n =8)。 4wk后处死动物抽取血液 ,分别采用酶动力法和放射免疫法检测血清淀粉酶和透明质酸 ;部分胰腺组织常规石蜡包埋切片 ,HE染色评定炎症反应的程度 ,改良V G染色观察胶原纤维 ,硫堇染色观察肥大细胞 ,TGF β1、α SMA和Ⅰ型胶原采用免疫组织化学染色 ;部分胰腺组织冻存于液氮 ,用于Westernblot检测α SMA的表达。结果　甘草酸干预组血清淀粉酶和透明质酸与对照组相比未见明显的差异 ;肥大细胞的数量和慢性脱颗粒较对照组明显减少 ;α SMA蛋白的表达明显较对照组下调 ;腺泡细胞炎症反应和纤维化程度较对照组明显减轻 ;胶原纤维染色显示 ,干预组小叶内明显减少 ;免疫组化染色显示TGF β1和Ⅰ型胶原表达较对照组下调。结论　甘草酸可能通过抑制肥大细胞的聚集活化和保护腺泡细胞膜的稳定 ,减少腺泡细胞的破坏 ,抑制胰腺星状细胞的活化增殖达到控制纤维化的发生     

Safety assessment of yerba mate (Ilex paraguariensis) dried extract: results of acute and 90 days subchronic toxicity studies in rats and rabbits

Acute toxicity of yerba mate dried extract (YMDE) was investigated in Wistar rats (6/sex/group) from single dose of 2g/kg body weight by intragastric administration and 14days monitoring. Subchronic toxicity was investigated in Wistar rats, by intragastric administration (10/sex/group), and in New Zealand rabbits by oral administration (3/sex/group) of 2g/kg body weight for 12weeks. Toxicological parameters included clinical signs, body weight, water, and food consumption, hematological and serum parameters, and histopathological assessment. Acute YMDE administration showed no effects on survival, clinical observations, macroscopic examination of organs, body weight or food, and water consumption. Sub-chronic administration of YMDE did not change behavior, body weight, and histopatological assessment of stomach, kidney, liver, and small gut. Moreover, most of biochemical and hematological parameters remained unchanged. In summary, the results of our preclinical toxicological investigation are indicative that the YMDE is well tolerated for both single and chronic administration.     

The effects of sigma ligands on the release of glutamate from rat striatal slices

This study investigated the effects of sigma receptor ligands on the release of endogenous amino acid neurotransmitters from rat striatal slices. The effect of haloperidol on release in slices prepared from 6-hydroxydopamine lesioned animals was also tested. Haloperidol, the (±) reduced metabolite of haloperidol, rimcazole and ifenprodil specifically reduced potassium-stimulated release of glutamate with IC₅₀ values between 20–60 M. The release of aspartate, -aminobutyric acid (GABA) and glycine was not affected. Haloperidol also reduced glutamate release from slices prepared from lesioned animals. The neuroleptic drug a-flupenthixol and the putative sigma receptor ligand R(+)3-(3-hydroxyphenyl)-N(n-propyl) piperidine (3-PPP) had no effect on release.These effects of the sigma ligands show that the inhibition of glutamate release is specific to this amino acid and also that it is not due to dopamine receptor blockade as those ligands which have low affinity for dopamine receptors were also effective in reducing release. A presynaptic location for sigma receptor sites, possibly associated with ion channels, could account for the effects of these ligands on transmitter release. Correspondence to: J. A. Davies at the above address     

The effects of isoproterenol on taurine concentration in the rat heart.

Administration of the beta-agonist isoproterenol to rats caused a sharp increase in the influx rate of taurine into the heart, but had no effect on the rate of biosynthesis of taurine in the heart. Influx rates of other amino acids were also stimulated, the distribution ratios, (dpm/g heart)/(dpm/ml plasma), of beta-amino acids being 3--4 times higher than alpha-amino acids. The doses of isoproterenol employed induced cardiac hypertrophy, but the stimulation of taurine influx appeared to be an independent phenomenon, in that near maximum stimulation of influx was achieved prior to stimulation of ornithine decarboxylase activity. Reserpine treatment also produced stimulation of taurine influx with no effect on biosynthesis. These results indicate a close connection between increased sympathomimetic activity and increased influx of amino acids.     

华蟾素对乳腺癌细胞株MCF-7的杀伤作用研究

目的研究华蟾素诱导人类乳腺癌MCF-7细胞的凋亡作用。方法利用CCK-8法检测华蟾素对乳腺癌MCF-7细胞的增殖抑制作用;用流式细胞术检测细胞的凋亡抑制率;利用倒置荧光显微镜观察细胞整体形态的变化;利用原子力显微镜(AFM)高分辨率、高灵敏度的特点,从纳米尺度上进一步观察细胞形貌及超微结构的变化。结果 CCK-8结果显示,华蟾素对MCF-7细胞的生长有明显的抑制作用,且随着剂量的增加(6.25～50 mg.L-1)而增大,当浓度为50 mg.L-1时,抑制率达到(68.40±1.02)%。采用流式细胞术对细胞凋亡的检测结果也表明华蟾素浓度为50 mg.L-1时,细胞晚期凋亡率最大,可达到(55.5±1.2)%。AFM与对照组相比,药物作用后,细胞开始坍塌变矮、细胞变小,周围呈月牙状或环状,浓度最大时,细胞中间出现较大孔洞。结论华蟾素能有效抑制MCF-7细胞的生长增殖并诱导其凋亡。利用AFM在单细胞水平上分析华蟾素对MCF-7细胞的作用,使分析结果更加全面。