Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Archives of Toxicology (v.81, #7)
Actin plays a crucial role in the phagocytosis and biological response to respirable quartz particles in macrophages by Petra Haberzettl; Rodger Duffin; Ursula Krämer; Doris Höhr; Roel P. F. Schins; Paul J. A. Borm; Catrin Albrecht (pp. 459-470).
The uptake of respirable quartz particles by alveolar macrophages (AM) is believed to cause an inflammatory response, which is discussed as a crucial step in quartz pathogenicity. However, little is known about the mechanism and the relevance of particle uptake. Therefore, the aim of this study was to analyze the role of the actin cytoskeleton in quartz particle uptake, reactive oxygen species generation (ROS) and tumour necrosis factor alpha (TNF-α) release. Primary rat alveolar and interstitial macrophages (IM) as well as a rat alveolar macrophage cell line (NR8383) were treated with quartz particles at various concentrations and time intervals. Particle uptake was studied using flow cytometry and light/fluorescence microscopy to analyze particle uptake and cytoskeleton recruitment. Intra- as well as extracellular ROS generation was analyzed by flow cytometry and electron spin resonance (ESR). Flow cytometric investigations demonstrated a dose- and time-dependent particle uptake. Primary AM showed a similar uptake indicating that the cell line provides a good model to investigate the mechanisms of particle uptake while primary IM had a lower uptake rate. Inhibition of actin polymerization using cytochalasin-D caused a significant reduction of particle uptake in NR8383 cells. The quartz induced dose-dependent increase of ROS generation and TNF-α release was also blocked by inhibition of actin polymerization. Our results demonstrate an active involvement of the cytoskeleton in uptake of quartz particles and suggest a role of the actin framework and/or the particle uptake in DQ12-induced ROS generation and cytokine release.
Keywords: Crystalline silica; Reactive oxygen species; TNF-α-release; Alveolar macrophages; Actin cytoskeleton
Immunohistochemical demonstration of the distribution of chloroquine (CQ) and its metabolites in CQ-poisoned mice by Ako Koreeda; Kosei Yonemitsu; Hiroe Kohmatsu; Sohtaro Mimasaka; Yuki Ohtsu; Toru Oshima; Kunio Fujiwara; Shigeyuki Tsunenari (pp. 471-478).
Chloroquine (CQ) distribution in tissues of acutely poisoned mice was demonstrated by immunohistochemistry using anti-CQ polyclonal antibodies (PAC). PAC recognized 4-amino-7-chloro-quinoline structure and sufficiently reacted with CQ and CQ’s metabolite bisdesethyl-chloroquine. In the brain, CQ and its metabolites (CQs) localized in the region of the choroids plexus, indicating an important role in the blood–cerebrospinal barrier system. In the heart, most regions showed diffused positive staining, and relatively strong reaction was observed in Purkinje cells, indicating an important role in acute CQ toxicity. In the lungs, CQs were observed in the bronchial epithelium, type II pneumocytes, and on the surface of alveolar walls. It was suggested that CQs were excreted to the alveolar wall with surfactant phospholipids, which are produced by type II pneumocytes. In the liver, CQs were concentrated in the centrolobular area rather than in the periportal area, in agreement with CQ’s metabolic pathway. In the kidneys, tubular cells were strongly stained compared to glomerular capsules, and the distal part of renal tubules was better stained than the proximal tubules. These findings suggested that CQs were predominantly excreted or reabsorbed through the distal tubules and the collecting duct. Distribution of CQs in tissues presented here were mostly consistent with the physico-chemical properties of CQ and its metabolites. However, the elucidation of CQs’ localization in Purkinje cells remains open. Further experimental studies at the level of microorganella will be needed to clarify the present result.
Keywords: Chloroquine; Immunohistochemistry; Tissue distribution; Acute toxicity; Mice
Effects of the anticancer dehydrotarplatin on cytochrome P450 and antioxidant enzymes in male rat tissues by Annalisa Nannelli; Andrea Messina; Sandra Marini; Silvia Trasciatti; Vincenzo Longo; Pier Giovanni Gervasi (pp. 479-487).
The effect of dehydrotarplatin (DTP), a new antineoplastic drug analogous to cisplatin, and its metabolite (Triacid) on the hepatic, renal and testicular CYP and antioxidant enzymes of male rats was investigated. The rats were treated i.p. with a single dose of DTP (25 mg kg−1 day−1) or Triacid (17.5 mg kg−1 day−1) and analysed 3 or 7 days post treatment. Three days after treatment, both drugs reduced body and liver weights, which partially recovered the control level after 7 days. DTP and, to a less extent, Triacid caused a depletion of plasmatic testosterone content and a down regulation in the liver of androgen dependent male specific CYP 2C11, but not of CYP 1A and 2E1, as determined by a significant decrease of 2α- and 16α-testosterone hydroxylase activities (markers for CYP 2C11) and of apoprotein immunoreactive with anti-rat CYP 2C11 antibodies. However, the activity of testicular 17α-progesterone hydroxylase, a key reaction in steroidogenesis, was not altered by these drugs. The DTP and Triacid administration did not cause any alteration of the plasmatic urea nitrogen and creatinine, known as markers of kidney toxicity. However, treatment with DTP, not Triacid, either 3 and 7 days post treatment, caused in the kidney microsomes a significant increase of the total CYP content, the CYP 4A-dependent (ω)- and (ω − 1)-lauric acid hydroxylase activities and apoprotein immunoreactive with anti-rat CYP 4A1. The present study also examined the enzymatic antioxidant status of kidney and liver. Neither DTP nor Triacid administration induced, with respect to control values, any alteration of hepatic and renal glutathione reductase, glutathione S-transferase, catalase, superoxide dismutase activities, hepatic GSH level and renal microsomal lipid peroxidation level. Among the antioxidant enzymes assayed, only the renal activity of glutathione peroxidase was significantly increased after DTP but not Triacid treatment. These results indicate that DTP at a dose of 25 mg/kg and Triacid cause a feminization of the CYP enzymes in male rat liver similar to that reported for cisplatin when administered at a low dose (5 mg/kg). However, unlike cisplatin, DTP and its metabolite were unable to enhance BUN and creatinine and cause any depression of CYP activities and antioxidant enzymes in the kidney, suggesting that DTP may have low or even no potential in inducing nephrotoxicity.
Keywords: Dehydrotarplatin; Hepatic, renal and testicular P450; Oxidative stress enzymes
Activation of mitogen activated protein kinase (MAPK) during carbon tetrachloride intoxication in the rat liver by Chinatsu Iida; Kozue Fujii; Terumi Kishioka; Ritsuko Nagae; Yuki Onishi; Ikuyo Ichi; Shosuke Kojo (pp. 489-493).
Carbon tetrachloride (CCl4: 4 ml/kg body weight as a 1:1 mixture of CCl4 and mineral oil) was orally administered to rats. After 12 h the activity of plasma AST (aspartate aminotransferase) and ALT (alanine aminotransferase) was significantly higher than that of the control group and plasma AST and ALT activities increased thereafter. These results indicated that the necrotic process was active at about 12 h and developed thereafter. After 2–24 h of CCl4 administration, the hepatic level of vitamin C, the most sensitive indicator of oxidative stress, decreased significantly, indicating that oxidative stress was significantly enhanced as early as 2 h after CCl4 intoxication and thereafter. Phosphorylated JNK (c-Jun NH2-terminal kinase) and phospho-ERK1/2 (extracellular signal-regulated kinase1/2) were significantly increased transiently 1–3 h after treatment with CCl4, while phosphorylated p38 decreased significantly 1–24 h after CCl4 treatment. These results indicated that the change in MAPKs (mitogen activated protein kinases) slightly preceded that in vitamin C, the most sensitive chemical indicator of oxidative stress.
Keywords: Carbon tetrachloride; CCl4 ; ERK; JNK; MAPK; Necrosis; Oxidative stress; P38; Vitamin C
Cisplatin-induced nephrotoxicity is associated with oxidative stress, redox state unbalance, impairment of energetic metabolism and apoptosis in rat kidney mitochondria by N. A. G. Santos; C. S. Catão; N. M. Martins; C. Curti; M. L. P. Bianchi; A. C. Santos (pp. 495-504).
The clinical use of cisplatin (cis-diamminedichloroplatinum II) is highly limited by its nephrotoxicity. The precise mechanisms involved in cisplatin-induced mitochondrial dysfunction in kidney have not been completely clarified. Therefore, we investigated in vivo the effects of cisplatin on mitochondrial bioenergetics, redox state, and oxidative stress as well as the occurrence of cell death by apoptosis in cisplatin-treated rat kidney. Adult male Wistar rats weighing 200–220 g were divided into two groups. The control group (n = 8) was treated only with an intraperitoneal (i.p.) injection of saline solution (1 ml per 100 g body weight), and the cisplatin group (n = 8) was given a single injection of cisplatin (10 mg/kg body weight, i.p.). Animals were sacrificed 72 h after the treatment. The cisplatin group presented acute renal failure characterized by increased plasmatic creatinine and urea levels. Mitochondrial dysfunction was evidenced by the decline in membrane electrochemical potential and the substantial decrease in mitochondrial calcium uptake. The mitochondrial antioxidant defense system was depleted, as shown by decreased GSH and NADPH levels, GSH/GSSG ratio, and increased GSSG level. Moreover, cisplatin induced oxidative damage to mitochondrial lipids, including cardiolipin, and oxidation of mitocondrial proteins, as demonstrated by the significant decrease of sulfhydryl protein concentrations and increased levels of carbonylated proteins. Additionally, aconitase activity, which is essential for mitochondrial function, was also found to be lower in the cisplatin group. Renal cell death via apoptosis was evidenced by the increased caspase-3 activity. Results show the central role of mitochondria and the intensification of apoptosis in cisplatin-induced acute renal failure, highlighting a number of steps that might be targeted to minimize cisplatin-induced nephrotoxicity.
Keywords: Cisplatin; Mitochondria; Nephrotoxicity; Reactive oxygen species (ROS)
Antiestrogenic effect of paradichlorobenzene in immature mice and rats by Osamu Takahashi; Shinshi Oishi; Masako Yoneyama; Akio Ogata; Hisashi Kamimura (pp. 505-517).
A significant increase/decrease in uterine and ovarian weights was occasionally seen in immature mice and rats subcutaneously administered paradichlorobenzene (PDCB) at doses of 22–67 mg/kg/day, but the results were not necessarily reproducible. PDCB at a dose of 800 mg/kg/day always reduced uterine and ovarian weights. Intraperitoneal PDCB at doses more than 400 mg/kg/day significantly inhibited the uterotrophic effect of β-estradiol (E2) in CD-1 (ICR) mice. E2-induced uterotrophy was dose-dependently prevented by 204–400 mg PDCB/kg/day in C57BL/6N (Ah responsive) mice but not DBA/2N (Ah non-responsive) mice. While PDCB did not bind to estrogen receptor (ERα) up to 10−3 M. Hepatic ethoxyresorufin-O-deethylase in adult female C57BL/6N mice was induced by ip administration of PDCB. Induction activity of PDCB may be 105–106 times lower than that of 2,3,7,8-tetrachlorodibenzo-p-dioxin. These results suggest that PDCB is a weak antiestrogenic/antiuterotrophic compound possibly due to ER modulation through arylhydrocarbon receptor.
Keywords: Paradichlorobenzene; Uterine weight; Antiuterotrophic; Arylhydrocarbon receptor
The DNA-damaging potential of tamoxifen in breast cancer and normal cells by Katarzyna Wozniak; Agnieszka Kolacinska; Maria Blasinska-Morawiec; Alina Morawiec-Bajda; Zbigniew Morawiec; Marek Zadrozny; Janusz Blasiak (pp. 519-527).
Tamoxifen (TAM) is a non-steroidal anti-estrogen used widely in the treatment and chemoprevention of breast cancer. TAM treatment can lead to DNA damage, but the mechanism of this process is not fully understood and the experimental data are often inconclusive. We compared the DNA-damaging potential of TAM in normal human peripheral blood lymphocytes and MCF-7 breast cancer cells by using the comet assay. In order to assess whether oxidative DNA damage may contribute to TAM-induced lesions, we employed two DNA repair enzymes: endonuclease III (Endo III) and formamidopyrimidine-DNA glycosylase (Fpg). The kinetics of repair of DNA damage was also measured. In order to evaluate the involvement of free radicals in the genotoxicity of TAM we pre-treated the cells with nitrone spin traps: DMPO and POBN. The use of common antioxidants: vitamin C, amifostine and genistein, helped to assess the contribution of free radicals. TAM damaged DNA in both normal and cancer cells, inducing mainly DNA strand breaks but not alkali-labile sites. The drug at 5 and 10 μM induced DNA double strand breaks (DSBs) in lymphocytes and at 10 μM in MCF-7 cells. We observed complete repair of DSBs in cancer cells by contrast with incomplete repair of these lesions in lymphocytes. In both types of cells TAM induced oxidized purines and pyrimidines. Incubation of the cells with nitrone spin traps and antioxidants decreased, with exception of amifostine in MCF-7 cells, the extents of DNA damage in both kinds of cells, but the results were more distinct in cancer cells. Our results indicate that TAM can be genotoxic for normal and cancer cells by free radicals generation. It seems to have a higher genotoxic potential for normal cells, which can be the result of incomplete repair of DNA DSBs. Free radicals scavengers can modulate TAM-induced DNA damage interfering with its antitumour activity in cancer cells.
Keywords: Amifostine; Breast cancer; Comet assay; DNA damage; DNA repair; Genistein; Tamoxifen; Human lymphocytes; MCF-7 cells; Vitamin C
Acute, nonfatal intoxication with trichloroethylene by Mariella Carrieri; Doriano Magosso; Pierpaolo Piccoli; Edoardo Zanetti; Andrea Trevisan; Giovanni Battista Bartolucci (pp. 529-532).
Nonfatal acute inhalation of trichloroethylene (TRI) at work was described. The subject, male, 54 years old, was drawn unconscious by a metal-degreasing machine and immediately sheltered in intensive care unit. Other than basic life support and common laboratory indices, blood and urine were collected to measure dose and kidney effect parameters such as TRI in blood and urine, trichloroethanol (TCE) and trichloroacetic acid (TCA) in urine, and total urinary proteins (TUP), urinary glutamine synthetase (GS) and urinary N-acetyl-ß-d-glucosaminidase (NAG). Two hours after accident, TRI in blood was 9 mg/l, but after 38 h it was below 1 mg/l. TCE and TCA have a peak 11 and 62 h after poisoning, respectively. Acute renal involvement was revealed by a peak of urinary proteins and enzymes 7 h after exposure with a second peak 74 h after. Seven day after hospitalisation the patient was dismissed with complete recovery. This nonfatal intoxication with TRI shows that the exposure was approximately 150 ppm, three times the ACGIH TLV (50 ppm) and that kidney was the only organ affected. Urinary enzymes, in particular GS, are good indices to monitor transient effects of TRI on the kidney.
Keywords: Trichloroethylene; Trichloroethanol; Trichloroacetic acid; Acute intoxication; Urinary proteins; Urinary enzymes