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Iagunov AS, Kartashev AV, Tokalov SV, Kiseleva LN. [Main milestones of development and application of ductal cytometry at the Russian Federal Research Center for Radiology and Surgical Technology, St. Petersburg]. Vopr Onkol 2008; 54:494-497. [PMID: 18942407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ductal cytometry provides data on cellular DNA and RNA levels and overall profile of specific proteins identifiable by monoclonal antibodies. Results of its long-term use in clinical and oncological research are presented. Application of dosage ranging 0.28-1.1 mGy/sec was followed by stable 1.8-2-fold increase in the myelokariocyte profile cbering DNA synthesis. Bone marrow proliferation did not increase until relatively low dosage was used. A study of combined effects of prolonged gamma irradiation and lead and cadmium ions on rat's hemopoiesis pointed to radiation as the sole causative factor when cadmium chloride was used. Hemopoietic characteristics came back to normal when a combination of lead acetate and ionizing radiation was used, as a result of the oppositely directed action of the two factors. Standard monoclonal antibodies should not be employed for evaluating immunological vigor of patients with malignant gliomas due to the presence of a specific pathological link in their immune system.
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102
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Jacquillet G, Barbier O, Rubera I, Tauc M, Borderie A, Namorado MC, Martin D, Sierra G, Reyes JL, Poujeol P, Cougnon M. Cadmium causes delayed effects on renal function in the offspring of cadmium-contaminated pregnant female rats. Am J Physiol Renal Physiol 2007; 293:F1450-60. [PMID: 17686954 DOI: 10.1152/ajprenal.00223.2007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the adult rat, chronic cadmium intoxication induces nephropathy with Fanconi-like features. This result raises the question of whether intoxication of pregnant rats has any deleterious effects on renal function in their offspring. To test this hypothesis, we measured the renal function of 2- to 60-day-old postnatal offspring from female rats administered cadmium chloride by the oral route (0.5 mg·kg−1·day−1) throughout their entire gestation. Investigations of rat offspring from contaminated pregnant rats showed the presence of cadmium in the kidney at gestational day 20. After birth, the cadmium kidney concentration increased from postnatal day 2 to day 60 (PND2 to PND60), presumably because of 1) milk contamination and 2) neonatal liver cadmium content release. Although the renal parameters (glomerular filtration, U/P inulin, and urinary excretion rate) were not significantly affected until PND45, renal failure appeared at PND60, as demonstrated by a dramatic decrease of the glomerular filtration rate associated with increased excretion of the main ions. In parallel, an immunofluorescence study of tight-junction protein expression of PND60 offspring from contaminated rats showed a disorganization of the tight-junction proteins claudin-2 and claudin-5, specifically expressed in the proximal tubule and glomerulus, respectively. In contrast, expression of a distal claudin protein, claudin-3, was not affected. In conclusion, in utero exposure of cadmium leads to toxic renal effects in adult offspring. These results suggest that contamination of pregnant rats is a serious and critical hazard for renal function of their offspring.
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Affiliation(s)
- G Jacquillet
- Unité Mixte de Recherche-Centre National de la Recherche Scientifique 6548, Université de Nice-Sophia Antipolis, Nice, France
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103
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Abstract
The present study was designed to explore the nephrotoxic effect of intraperitoneal acute administration of CdCl2 (2.5 and 5 mg kg(-1) b.w.) in rats. A number of toxicological parameters in kidney were examined including malondialdehyde (MDA) and endogenous antioxidants, e.g., catalase (CAT), superoxide dismutase (SOD) and Glutathione Peroxidase (GPx). The parameters that indicate tissue damage such as serum urea and creatinine were also determined, along with the ultrastructural changes of kidneys. A correlation was found between the dose and the intensity of changes. The results demonstrated that cadmium administration increased renal MDA but decreased CAT, SOD and GPx activities. In parallel, serum creatinine and urea elevated. The glomerular ultrastructural changes observed in cadmium-treated rats included narrowing of the capillary lumen and swelling of the capillary endothelium with occasional loss of fenestrae. The mesangium was wide with increased mesangial matrix. Loss of homogenous appearance of basement membrane displaying ondulation and thickening in many areas and deterioration of the slit membrane structures formed by the podocytes were also noted. The effects of cadmium on proximal cell ultrastructure were focal loss of brush border, nuclear membrane damage, chromatin condensation, swelling of the mitochondria with regression of mitochondrial cristae, degranulation and disintegration of protein-synthesizing structures such as rough endoplasmic reticulum, increased number of lysosomes and ultimately cell death.
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104
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Ullrich ND, Koschak A, MacLeod KT. Oestrogen directly inhibits the cardiovascular L-type Ca2+ channel Cav1.2. Biochem Biophys Res Commun 2007; 361:522-7. [PMID: 17662243 DOI: 10.1016/j.bbrc.2007.07.054] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 07/16/2007] [Indexed: 12/21/2022]
Abstract
Oestrogen can modify the contractile function of vascular smooth muscle and cardiomyocytes. The negative inotropic actions of oestrogen on the heart and coronary vasculature appear to be mediated by L-type Ca(2+) channel (Ca(v)1.2) inhibition, but the underlying mechanisms remain elusive. We tested the hypothesis that oestrogen directly inhibits the cardiovascular L-type Ca(2+) current, I(CaL). The effect of oestrogen on I(CaL) was measured in Ca(v)1.2-transfected HEK-293 cells using the whole-cell patch-clamp technique. The current revealed typical activation and inactivation profiles of nifedipine- and cadmium-sensitive I(CaL). Oestrogen (50 microM) rapidly reduced I(CaL) by 50% and shifted voltage-dependent activation and availability to more negative potentials. Furthermore, oestrogen blocked the Ca(2+) channel in a rate-dependent way, exhibiting higher efficiency of block at higher stimulation frequencies. Our data suggest that oestrogen inhibits I(CaL) through direct interaction of the steroid with the channel protein.
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Affiliation(s)
- Nina D Ullrich
- Imperial College London, Cardiac Medicine, NHLI London, UK.
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105
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Abstract
We have previously found that the DNA fragment from nucleotides (nts) -287 to +110 in the HSP70B' gene is a functional promoter responding to Cadmium Chloride-induced cytotoxicity (Wada et al., Biotechnol Bioeng, 92, 410-415, 2005). In order to increase the cytotoxic response of this promoter, we first determined the location of the cytotoxic responding element (CRE) and then constructed tandem repeats of the CRE in front of the HSP70B' promoter. 5'- and 3'-deletion analysis revealed that the DNA fragment from nts -192 to -56 in the HSP70B' gene induces a significant response to cytotoxicity. When the AP-1 binding site in this region was mutated, the basal activity of HSP70B' gene promoter decreased but the cytotoxic response was unchanged. Thus, the CRE is located in nts -192 to -56 in the HSP70B' promoter, and the AP-1 binding site is not essential for the cytotoxic response. In addition, cells transfected with a luciferase construct carrying three tandem repeats of the CRE upstream of the HSP70B' promoter and containing AP-1 binding site mutation, showed a 2.28-fold higher response than that of no repeats. Moreover, the detection limit of Cadmium Chloride in the cells was 382 pmol/mL. Thus, highly sensitive sensor cells for Cadmium Chloride can be constructed using a HSP70B' promoter construct containing upstream tandem repeats of the CRE and mutation of the AP-1 binding site.
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Affiliation(s)
- Ken-Ichi Wada
- Cell Engineering Technology Group, Biomaterials Center, National Institute for Materials Science, 1-1, Namiki, Tsukuba, Ibaraki 305-0044, Japan
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106
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Yang JL, Liu LW, Gong YQ, Huang DQ, Wang F, He LL. [Analysis of genomic DNA methylation level in radish under cadmium stress by methylation-sensitive amplified polymorphism technique]. Zhi Wu Sheng Li Yu Fen Zi Sheng Wu Xue Xue Bao 2007; 33:219-26. [PMID: 17556809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The level of cytosine methylation induced by cadmium in radish (Raphanus sativus L.) genome was analysed using the technique of methylation-sensitive amplified polymorphism (MSAP). The MSAP ratios in radish seedling exposed to cadmium chloride at the concentration of 50, 250 and 500 mg/L were 37%, 43% and 51%, respectively, and the control was 34%; the full methylation levels (C(m)CGG in double strands) were at 23%, 25% and 27%, respectively, while the control was 22%. The level of increase in MSAP and full methylation indicated that de novo methylation occurred in some 5'-CCGG sites under Cd stress. There was significant positive correlation between increase of total DNA methylation level and CdCl(2) concentration. Four types of MSAP patterns: de novo methylation, de-methylation, atypical pattern and no changes of methylation pattern were identified among CdCl(2) treatments and the control. DNA methylation alteration in plants treated with CdCl(2) was mainly through de novo methylation.
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Affiliation(s)
- Jin-Lan Yang
- National Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
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107
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Alvarado NE, Cancio I, Hylland K, Marigómez I, Soto M. Immunolocalization of metallothioneins in different tissues of turbot (Scophthalmus maximus) exposed to Cd. Histol Histopathol 2007; 22:719-28. [PMID: 17455146 DOI: 10.14670/hh-22.719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Metallothioneins (MT) were localized by immunochemistry in different organs and cell compartments of turbot exposed to sublethal concentrations (100 ppb) of Cd for 7 days. The polyclonal rabbit anti-cod MT antibody (NIVA, Norway) applied herein exhibited positive cross-reactivity with turbot MTs. Immunoreactive MTs were localized in the branchial epithelium, in the liver and in the kidney of turbot. In Cd exposed fishes MTs were demonstrated mainly in branchial chloride cells (CC) and to a lesser extend in the area where progenitor cells are located and in the cells of the respiratory epithelium (secondary lamellae). A higher staining intensity for MTs was observed in CC of the interlamellar space of the main branchial epithelium in comparison with control CC. MT-staining was also observed in the chondroblasts of the cartilage and in the erythrocytes within blood vessels both in control and Cd-exposed specimens. MT immunoreaction was high in the liver hepatocytes and weak in the epithelium of the proximal portion of the kidney in exposed turbot. The tegument, spleen and muscle were devoid of any immunolabelling in both treatments. Ultrastructural studies at the transmission electron microscope revealed that Cd-induced MTs were mainly located in the cytoplasm of gill CC, the lysosomes and the cytoplasm of hepatocytes and in the basal labyrinth of kidney proximal nephrocytes. The differential localization/induction of MTs in different cell types described hereby suggests that the quantification of the specific expression of MT may be used in biomonitoring programs as a biomarker of Cd exposure in aquatic environments.
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Affiliation(s)
- N E Alvarado
- Department of Zoology and Animal Cell Biology, School of Science and Technology, University of the Basque Country, Bilbao, Spain
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108
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Jain M, Pal M, Gupta P, Gadre R. Effect of cadmium on chlorophyll biosynthesis and enzymes of nitrogen assimilation in greening maize leaf segments: role of 2-oxoglutarate. Indian J Exp Biol 2007; 45:385-9. [PMID: 17477312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Supply of cadmium chloride (0.5 mM) inhibited chlorophyll formation in greening maize leaf segments, while lower concentration of Cd (0.01 mM) slightly enhanced it. Inclusion of 2-oxoglutarate (2-OG, 0.1-10 mM) in the incubation mixture increased chlorophyll content in the absence as well as presence of Cd. Substantial inhibition of chlorophyll formation by Cd was observed at longer treatment both in the absence and presence of 2-OG. When the tissue was pre-incubated with 2-OG or Cd, the inhibition (%) of chlorophyll formation by Cd was lowered in the presence of 2-OG. Treatment with Cd inhibited ALAD activity and ALA formation and the inhibition (%) of ALA formation by Cd was strongly reduced in the presence of 2-OG. Glutamate dehydrogenase (GDH) activity was increased by the supply of Cd both in the absence as well as presence of 2-OG. In the presence of 2-OG, Cd supply significantly increased glutamate synthase (GOGAT) activity and reduced inhibition (%) of glutamine synthetase (GS) activity. The results suggested the involvement of the glutamine synthetase/glutamate synthase (GS/GOGAT) pathway of ammonia assimilation to provide the precursor, glutamate, for ALA synthesis under Cd toxicity and 2-OG supplementation.
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Affiliation(s)
- Meeta Jain
- School of Biochemistry, Devi Ahilya Vishwavidyalaya, Takshashila Parisar, Khandwa Road, Indore 452 017, India
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109
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Pena LB, Pasquini LA, Tomaro ML, Gallego SM. 20S proteasome and accumulation of oxidized and ubiquitinated proteins in maize leaves subjected to cadmium stress. Phytochemistry 2007; 68:1139-46. [PMID: 17399749 DOI: 10.1016/j.phytochem.2007.02.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 02/08/2007] [Accepted: 02/19/2007] [Indexed: 05/14/2023]
Abstract
In order to examine the possible involvement of the 20S proteasome in degradation of oxidized proteins, the effects of different cadmium concentrations on its activities, protein abundance and oxidation level were studied using maize (Zea mays L.) leaf segments. The accumulation of carbonylated and ubiquitinated proteins was also investigated. Treatment with 50 microM CdCl(2) increased both trypsin- and PGPH-like activities of the 20S proteasome. The incremental changes in 20S proteasome activities were probably caused by an increased level of 20S proteasome oxidation, with this being responsible for degradation of the oxidized proteins. When leaf segments were treated with 100 microM CdCl(2), the chymotrysin- and trypsin-like activities of the 20S proteasome also decreased, with a concomitant increase in accumulation of carbonylated and ubiquitinated proteins. With both Cd(2+) concentrations, the abundance of the 20S proteasome protein remained similar to the control experiments. These results provide evidence for the involvement of this proteolytic system in cadmium-stressed plants.
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Affiliation(s)
- Liliana B Pena
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires (C1113AAC), Argentina
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110
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Abu-Bakar A, Lämsä V, Arpiainen S, Moore MR, Lang MA, Hakkola J. Regulation ofCYP2A5Gene by the Transcription Factor Nuclear Factor (Erythroid-Derived 2)-Like 2. Drug Metab Dispos 2007; 35:787-94. [PMID: 17303623 DOI: 10.1124/dmd.106.014423] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We have previously shown that cadmium, a metal that alters cellular redox status, induces CYP2A5 expression in nuclear factor (erythroid-derived 2)-like 2 wild-type (Nrf2+/+) mice but not in the knockout (Nrf2-/-) mice. In the present studies, the potential role of Nrf2 in cadmium-mediated regulation of Cyp2a5 gene was investigated in mouse primary hepatocytes. Cadmium chloride (CdCl2) caused a time-dependent induction of the CYP2A5 at mRNA, protein, and activity levels, with a substantial increase observed within 3 h of exposure. Immunoblotting showed cadmium-dependent nuclear accumulation of Nrf2 within 1 h of exposure. Cotransfection of mouse primary hepatocytes with Cyp2a5 promoter-luciferase reporter plasmids and Nrf2 expression plasmid resulted in a 3-fold activation of Cyp2a5 promoter-mediated transcription relative to the control. Deletion analysis of the promoter localized the Nrf2 responsive region to an area from -2656 to -2339 base pair. Computer-based sequence analysis identified two putative stress response elements (StRE) within the region at positions -2514 to -2505 and -2386 to -2377. Chromatin immunoprecipitation and electrophoretic mobility shift assays showed that interaction of the more proximal StRE with Nrf2 was stimulated by CdCl2. Finally, site-directed mutagenesis of the proximal StRE in Cyp2a5 promoter-luciferase reporter plasmids abolished Nrf2-mediated induction. Collectively, the results indicate that Nrf2 activates Cyp2a5 transcription by directly binding to the StRE in the 5'-flanking region of the gene. This acknowledges Cyp2a5 as the first phase I xenobiotic-metabolizing gene identified under the control of the StRE-Nrf2 pathway with a potential role in adaptive response to cellular stress.
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Affiliation(s)
- A'edah Abu-Bakar
- National Research Centre for Environmental Toxicology, University of Queensland, Brisbane, QLD, Australia.
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111
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Varga C, Laszlo F, Fritz P, Cavicchi M, Lamarque D, Horvath K, Posa A, Berko A, Whittle BJR. Modulation by heme and zinc protoporphyrin of colonic heme oxygenase-1 and experimental inflammatory bowel disease in the rat. Eur J Pharmacol 2007; 561:164-71. [PMID: 17292349 DOI: 10.1016/j.ejphar.2006.12.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2006] [Revised: 12/20/2006] [Accepted: 12/21/2006] [Indexed: 01/12/2023]
Abstract
Reactive oxygen species, suggested to be involved in inflammatory bowel disease, may be modulated by endogenous anti-oxidant products of heme oxygenase-1 (HO-1). In the present work, HO-1 expression in trinitrobenzene sulphonic acid (TNBS)-induced colitis in the rat and the effects of HO-1 modulation, particularly by the HO-1 inducer, heme, were further evaluated. Colitis was induced by intracolonic challenge with TNBS and assessed macroscopically and by myeloperoxidase (MPO) assay. Heme oxygenase activity was determined by measurement of bilirubin formation and HO-1 protein expression was determined by Western blotting. TNBS challenge led to an early and substantial induction of HO-1 protein expression and heme oxygenase activity in the colon that peaked after 48-72 h and declined over 10 days. Heme (30 micromol/kg/day, s.c) increased colonic HO-1 protein expression and enzyme activity and decreased colonic damage and myeloperoxidase activity. Short-term administration of cadmium chloride (2 mg/kg, s.c.), another known HO-1 inducer, also reduced the colonic injury and myeloperoxidase levels. In contrast, the HO-1 inhibitor, zinc protoporphyrin (50 micromol/kg/day, s.c) significantly increased the colonic damage and myeloperoxidase activity over 10 days, as did tin protoporphyrin (30 micromol/kg/day, s.c). These results support the proposal that induction of HO-1 provides a protective mechanism in this model under both acute and more-chronic conditions, and that its selective up-regulation could thus be of therapeutic potential in colitis.
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Affiliation(s)
- Csaba Varga
- Department Comparative Physiology, Faculty of Sciences, University Szeged, Szeged, Hungary.
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112
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Lemaire F, Mandon CA, Reboud J, Papine A, Angulo J, Pointu H, Diaz-Latoud C, Lajaunie C, Chatelain F, Arrigo AP, Schaack B. Toxicity assays in nanodrops combining bioassay and morphometric endpoints. PLoS One 2007; 2:e163. [PMID: 17235363 PMCID: PMC1769465 DOI: 10.1371/journal.pone.0000163] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 09/18/2006] [Indexed: 11/19/2022] Open
Abstract
Background Improved chemical hazard management such as REACH policy objective as well as drug ADMETOX prediction, while limiting the extent of animal testing, requires the development of increasingly high throughput as well as highly pertinent in vitro toxicity assays. Methodology This report describes a new in vitro method for toxicity testing, combining cell-based assays in nanodrop Cell-on-Chip format with the use of a genetically engineered stress sensitive hepatic cell line. We tested the behavior of a stress inducible fluorescent HepG2 model in which Heat Shock Protein promoters controlled Enhanced-Green Fluorescent Protein expression upon exposure to Cadmium Chloride (CdCl2), Sodium Arsenate (NaAsO2) and Paraquat. In agreement with previous studies based on a micro-well format, we could observe a chemical-specific response, identified through differences in dynamics and amplitude. We especially determined IC50 values for CdCl2 and NaAsO2, in agreement with published data. Individual cell identification via image-based screening allowed us to perform multiparametric analyses. Conclusions Using pre/sub lethal cell stress instead of cell mortality, we highlighted the high significance and the superior sensitivity of both stress promoter activation reporting and cell morphology parameters in measuring the cell response to a toxicant. These results demonstrate the first generation of high-throughput and high-content assays, capable of assessing chemical hazards in vitro within the REACH policy framework.
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Affiliation(s)
- Frédéric Lemaire
- Commissariat à l'Energie Atomique, DSV, Cellular Responses and Dynamics Department, Laboratoire Biopuces, Commissariat à l'Energie Atomique Centre de Grenoble, Grenoble, France
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113
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Dardenne F, Nobels I, De Coen W, Blust R. Dose-response relationships and statistical performance of a battery of bacterial gene profiling assays. Appl Microbiol Biotechnol 2007; 75:223-34. [PMID: 17225096 DOI: 10.1007/s00253-006-0808-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 12/08/2006] [Accepted: 12/11/2006] [Indexed: 11/29/2022]
Abstract
Because of increasing awareness and legislative demands, there is a demand for the development and use of biological assays for the assessment of the toxicity of chemicals, environmental samples. Recently, a growing number of bacterial reporter assays have been developed and implemented. Nevertheless, little data is published on the performance of these assays in terms of analytical parameters. We present results on a battery of 14 transgenic Escherichia coli strains carrying different promoter::reporter fusions. Growth characteristics and basal expression levels were modeled and fitted, data show that growth curves should be taken into account during test development. Our study shows that the induction profiles reflect the mode of action, e.g., paraquat clearly induces the soxRS operon. The sensitivity of the assay compares well to that of whole organism tests, e.g., fish and Daphnia for polar organics. Metal toxicity is detected less efficiently, e.g., cadmium is detected near the LC50 of carp, considered a relatively insensitive species towards cadmium. The assay variability ranges from 10 to 40% depending on the strain, comparable to that of other bioassays. The variability was shown to be determined by the intrinsic traits of the promoter-strain combination, not by operating conditions.
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Affiliation(s)
- F Dardenne
- Department of Biology, Ecophysiology, Biochemistry and Toxicology Group, University of Antwerp, Groenenborgerlaan 171/U7, Antwerp, Belgium.
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114
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Hyun JS, Satsu H, Shimizu M. Cadmium induces Interleukin-8 production via NF-κB activation in the human intestinal epithelial cell, Caco-2. Cytokine 2007; 37:26-34. [PMID: 17391980 DOI: 10.1016/j.cyto.2007.02.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Revised: 12/12/2006] [Accepted: 02/07/2007] [Indexed: 11/21/2022]
Abstract
In the present study, we investigated the effect of CdCl2 on the inflammatory cytokines in human intestinal Caco-2 cells. The secretion of IL-8 from Caco-2 cells was significantly increased in a dose- and time-dependent manner, whereas the secretion of such other inflammatory cytokines as TNF-alpha and IFN-gamma was not changed. And IL-8 mRNA level was significantly increased by exposing the cells to CdCl2. A reporter vector containing the IL-8 promoter region was then constructed to determine the IL-8 transcriptional activity. The results of this assay demonstrated that the transcriptional activity of IL-8 was increased by CdCl2. Treatment with PDTC, an NF-kappaB inhibitor, suppressed the IL-8 secretion in Caco-2 cells. Site-directed mutation of the NF-kappaB consensus element in the human IL-8 promoter abolished the increased transcriptional activity by CdCl2. The increased transcriptional activity caused by CdCl2 was also suppressed in an NF-kappaB knock-down Caco-2 cell line that had been stably established by the RNAi method. The increase in translocation of the NF-kappaB protein into the nucleus and I-kappaB alpha degradation resulting from CdCl2 stimulation was also confirmed by a Western analysis. Our results suggest that CdCl2 induced IL-8 secretion, its transcription, and its transcriptional activation regulated by NF-kappaB via I-kappaB alpha degradation.
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Affiliation(s)
- Ja Shil Hyun
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan.
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115
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Malekzadeh P, Khara J, Farshian S, Jamal-Abad AK, Rahmatzadeh S. Cadmium toxicity in maize seedlings: changes in antioxidant enzyme activities and root growth. Pak J Biol Sci 2007; 10:127-131. [PMID: 19069998 DOI: 10.3923/pjbs.2007.127.131] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
In acid soils worldwide cadmium toxicity is a major factor limiting plant growth. The harmful effect of cadmium is initially expressed as a reduction in growth followed by several other secondary responses. In this study, some of the toxic effects of Cd(+2) like induction of oxidative stress were investigated. The effect of metal ion on the root growth was considered in maize plants. Maize (Zea mays L.) seeds were sterilized with 2.5% sodium hypochlorite solution for 15 min and washed thoroughly with distilled water. These seeds then germinated in petri dish (20 cm) containing distilled water at 37 degrees C in the dark. After a 1 day incubation, uniformly germinated seeds were selected and transferred to Petri dishes (9.0 cm) containing filter paper moistened with 10 mL of distilled water. Each Petri dish contained 12 germinated seeds. Each treatment was replicated 4 times. The germinated seeds were allowed to grow at 27 degrees C in darkness and 5 mL of test solution was added to each Petri dish in the second day. The test solution contained 0, 0.25, 0.5, 0.75, 1, 3 and 5 mM CdCl2. Cadmium treatments, increased GPX and APX activities in root in the presence of 0.25, 0.5, 0.75 mM concentrations, but their activities were constant in 1, 3 and 5 mM. Increased concentrations of CdCl2 from 0.25 to 5 mM decreased root length progressively. However, no reduction of shoot length by CdCl2 was observed.
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116
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Horemans N, Raeymaekers T, Van Beek K, Nowocin A, Blust R, Broos K, Cuypers A, Vangronsveld J, Guisez Y. Dehydroascorbate uptake is impaired in the early response of Arabidopsis plant cell cultures to cadmium. J Exp Bot 2007; 58:4307-17. [PMID: 18182433 DOI: 10.1093/jxb/erm291] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The balance between antioxidants, such as ascorbate (ASC) and glutathione, and oxidative reactive oxygen species (ROS) is known to play a pivotal role in the response of plant cells to abiotic stress. Here cell cultures of Arabidopsis thaliana were investigated with regard to their response to elevated levels of cadmium. At concentrations <100 microM, Cd induces a rapid and concentration-dependent H(2)O(2) accumulation. This response could be inhibited by diphenylene iodonium (DPI, 20 microM). Reverse transcription-PCR analysis of three RBOH (respiratory burst oxidase homologues) genes showed an increased transcription of RBOHF after 15 min. No change in ASC concentration was observed during the first 3 h after Cd addition. In contrast, glutathione levels completely diminished within 1 h. This drop could be attributed to an increase in phytochelatin 4. At the plasma membrane, Cd further induced a significant decrease in dehydroascorbate (DHA) uptake activity (up to 90% inhibition after 4 h). This decrease is not present when cells are treated with LaCl(3) before exposure to CdCl(2). LaCl(3) is a typical inhibitor of Ca channels and prevents Cd uptake in these cells as well as the Cd-induced ROS production. Therefore, these results appear to indicate that Cd uptake is a prerequisite for the change in DHA transport activity. However, DPI did not prevent the drop in DHA uptake activity present in Cd-treated Arabidopsis cells, indicating that this response seems to be independent of the Cd-induced H(2)O(2) production.
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Affiliation(s)
- Nele Horemans
- Department of Biology, Plant Physiology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
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117
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Gorinova N, Nedkovska M, Todorovska E, Simova-Stoilova L, Stoyanova Z, Georgieva K, Demirevska-Kepova K, Atanassov A, Herzig R. Improved phytoaccumulation of cadmium by genetically modified tobacco plants (Nicotiana tabacum L.). Physiological and biochemical response of the transformants to cadmium toxicity. Environ Pollut 2007; 145:161-70. [PMID: 16762468 DOI: 10.1016/j.envpol.2006.03.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 02/14/2006] [Accepted: 03/22/2006] [Indexed: 05/08/2023]
Abstract
The response of tobacco plants (Nicotiana tabacum L.)--non-transformed and transformed with a metallothionein gene MThis from Silene vulgaris L.--to increase cadmium supply in the nutrient solution was compared. The transgenic plants accumulated significantly more Cd both in the roots and the leaves. Visual toxicity symptoms and disturbance in water balance were correlated with Cd tissue content. Treatment with 300 microM CdCl(2) resulted in inhibition of photosynthesis and mobilization of the ascorbate-glutathione cycle. Treatment with 500 microM CdCl(2) led to irreversible damage of photosynthesis and oxidative stress. An appearance of a new peroxidase isoform and changes in the leaf polypeptide pattern were observed at the highest Cd concentration. The level of non-protein thiols gradually increased following the Cd treatment both in transgenic and non-transformed plants.
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Affiliation(s)
- N Gorinova
- AgroBioInstitute, 8 Dragan Tzankov Blvd., 1164 Sofia, Bulgaria.
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118
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Luchese C, Zeni G, Rocha JBT, Nogueira CW, Santos FW. Cadmium inhibits δ-aminolevulinate dehydratase from rat lung in vitro: Interaction with chelating and antioxidant agents. Chem Biol Interact 2007; 165:127-37. [PMID: 17187767 DOI: 10.1016/j.cbi.2006.11.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 11/20/2006] [Accepted: 11/21/2006] [Indexed: 11/19/2022]
Abstract
The effect of cadmium (Cd(2+)) on delta-aminolevulinate dehydratase (delta-ALA-D) activity from rat lung in vitro was investigated. delta-ALA-D activity, a parameter for metal intoxication, has been reported as a target of Cd(2+) in different tissues. The protective effect of monotherapies with dithiol chelating (meso-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercaptopropane-1-sulfonic acid (DMPS)) or antioxidant agents (ascorbic acid, diphenyl diselenide (PhSe)(2), and N-acetylcysteine (NAC)) was evaluated. The effect of a combined therapy (dithiol chelatingxantioxidant agent) was also studied. Zinc chloride (ZnCl(2)) and dithiothreitol (DTT) were used to investigate the mechanisms involved in cadmium, chelating and antioxidant effects on delta-ALA-D activity. Cadmium inhibited rat lung delta-ALA-D activity at low concentrations. DTT (3mM), but not ZnCl(2) (100microM), protected the inhibition of enzyme activity caused by Cd(2+). Chelating agents were not effective in restoring the enzyme activity. DMPS and DMSA presented inhibitory effect on enzyme activity. DTT restored the inhibition caused by both chelating agents, but ZnCl(2) restored only the inhibitory effect induced by DMSA. These compounds caused a marked potentiation of delta-ALA-D inhibition induced by Cd(2+). ZnCl(2) did not restore inhibition of enzyme activity caused by Cd(2+) plus chelating agents. Conversely, DTT restored the inhibition induced by Cd(2+)/DMSA, but not by Cd(2+)/DMPS. Antioxidants were not effective in ameliorating delta-ALA-D inhibition induced by Cd(2+), whereas ascorbic acid potentiated the enzyme inhibition induced by this metal. A combined effect of Cd(2+)xDMPSx(PhSe)(2) and Cd(2+)xDMPSxNAC was observed. There was no combined effect of Cd(2+)xchelatorxantioxidants when DMSA was used. This study demonstrated that Cd(2+)inhibited delta-ALA-D activity and chelating and antioxidant agents, alone or combined, did not restore the enzyme activity. In contrast, these compounds potentiated the inhibition induced by Cd(2+) in rat lung.
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Affiliation(s)
- Cristiane Luchese
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, CEP 97105-900, RS, Brazil
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119
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Juhel G, O'Halloran J, Culloty SC, O'riordan RM, Davenport J, O'Brien NM, James KF, Furey A, Allis O. In vivo exposure to microcystins induces DNA damage in the haemocytes of the zebra mussel, Dreissena polymorpha, as measured with the comet assay. Environ Mol Mutagen 2007; 48:22-9. [PMID: 17163507 DOI: 10.1002/em.20271] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The Comet assay was used to investigate the potential of the biotoxin microcystin (MC) to induce DNA damage in the freshwater zebra mussel, Dreissena polymorpha. Mussels maintained in the laboratory were fed daily, over a 21-day period, with one of four strains of the cyanobacterium, Microcystis aeruginosa. Three of the strains produced different profiles of MC toxin, while the fourth strain did not produce MCs. The mussels were sampled at 0, 7, 14, and 21 days by withdrawing haemocytes from their adductor muscle. In addition, a positive control was performed by exposing a subsample of the mussels to water containing cadmium chloride (CdCl(2)). Cell viability, measured with the Fluorescein Diacetate/Ethidium Bromide test, indicated that the MC concentrations, to which the mussels were exposed, were not cytotoxic to the haemocytes. The Comet assay performed on the haemocytes indicated that exposure to CdCl(2) produced a dose-responsive increase in DNA damage, demonstrating that mussel haemocytes were sensitive to DNA-damaging agents. DNA damage, measured as percentage tail DNA (%tDNA), was observed in mussels exposed to the three toxic Microcystis strains, but not in mussels exposed to the nontoxic strain. Toxin analysis of the cyanobacterial cultures confirmed that the three MC-producing strains exhibit different toxin profiles, with the two MC variants detected being MC-LF and MC-LR. Furthermore, the DNA damage that was observed appeared to be strain-specific, with high doses of MC-LF being associated with a higher level of genotoxicity than low concentrations of MC-LR. High levels of MC-LF also seemed to induce relatively more persistent DNA damage than small quantities of MC-LR. This study is the first to demonstrate that in vivo exposure to MC-producing strains of cyanobacteria induces DNA damage in the haemocytes of zebra mussels and confirms the sublethal toxicity of these toxins.
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Affiliation(s)
- Guillaume Juhel
- Department of Zoology, Ecology and Plant Science, Environmental Research Institute, University College Cork, Cork, Ireland.
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120
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Fenik SI, Solodushko VG, Kaliniak TB, Blium IB. [The role of Cd-binding proteins and phytochelatins in the formation of cadmium resistance in Nicotiana plumbaginifolia cell lines]. Tsitol Genet 2007; 41:9-15. [PMID: 17427412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Nicotiana plumbaginifolia callus lines with the equal resistance to cadmium have been produced under different selective conditions--either without inhibition of the phytochelatin synthesis (line Cd-R) or in the presence of the inhibitor butionine sulfoximine (line Cd-Ri). The level of phytochelatin synthesis in the line Cd-R five-fold exceeded the control value and in the line Cd-Ri it was twice as much as in the control. It was shown that in the control line mainly three cadmium-binding proteins are expressed of the molecular weihgts 41, 34 and 19 kD. The common feature of the both resistant lines is the expression of the cadmium-binding proteins of 40, 37 and 19 kD. The resistant lines differ with respect to the synthesis of relatively low-molecular cadmium-binding proteins. The proteins of the molecular weights 12.5, 11.5 and 9 kD are expressed in the line Cd-R, while the proteins of 13 and 10 kD are expressed in the line Cd-Ri. It was supposed that both the phytochelatins and the Cd-binding proteins contribute to the resisitance of N. plumbaginifolia callus lines to cadmium and the lack of the phytochelatins can be equilibrated by the changes in the low-molecular Cd-binding protein synthesis.
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121
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Swiergosz-Kowalewska R, Holewa I. Cadmium, zinc and iron interactions in the tissues of bank vole Clethrionomys glareolus after exposure to low and high doses of cadmium chloride. Biometals 2006; 20:743-9. [PMID: 17120143 DOI: 10.1007/s10534-006-9037-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 09/26/2006] [Indexed: 11/29/2022]
Abstract
In present study, bank voles Clethrionomys glareolus were peritioneally injected with different doses of cadmium, 0, 1.5, 3.0 mg Cd/kg body mass. Animals were sacrificed on the 21st day after cadmium exposure and the liver and kidney were obtained for cadmium, zinc and iron analysis using atomic absorption spectrometry. Results showed that cadmium had accumulated in the tissues according to dosage and sex. Cadmium affected the survival and body masses of dosed females. Cadmium decreased the iron concentrations in the liver of voles, whereas zinc concentrations increased in both the kidney and liver.
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Affiliation(s)
- Renata Swiergosz-Kowalewska
- Department of Ecotoxicology, Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
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122
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Znidaric MT, Pucer A, Fatur T, Filipic M, Scancar J, Falnoga I. Metal binding of metallothioneins in human astrocytomas (U87 MG, IPDDC-2A). Biometals 2006; 20:781-92. [PMID: 17115260 DOI: 10.1007/s10534-006-9041-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 10/06/2006] [Indexed: 11/30/2022]
Abstract
Astroglia cells structurally and nutritionally support neurons in the central nervous system. They play an important role in guiding the construction of the nervous system and controlling the chemical and ionic environment of neurons. They also represent the major sites for accumulation and immobilisation of toxic metal ions most probably connected with metallothioneins. For this reason astroglia cells possess high cytosolic levels of metallothioneins I, II and III (MT-I,II,III). Our aim was to establish the inducibility and metal binding of MTs in two human astrocytoma cell lines, U87 MG (astrocytoma-glioblastoma, grade IV) and IPDDC-2A (astrocytoma, grade II), on exposure to cadmium chloride (1 microM). MTs were identified by molecular weight (size exclusion chromatography) and their metal content (Cd, Zn and Cu) to follow the interactions between metals. We showed that MTs are constitutively expressed in both human astrocytoma cell lines. In accordance with the higher malignancy grade of U87 MG, the amount of MTs was higher in U87 MG than in IPDDC-2A cells. After 24 hours of exposure to Cd their expression greatly increased in both cell lines and they were capable of immobilising almost all water soluble Cd. Induction of MTs in U87 MG cells was additionally followed up to 48 hours with exposure to different concentrations of CdCl(2) (1, 10 microM). Induction was a time dependent process throughout the period. Isoform III (identified by chromatographic separation of isoform III from I/II) was present at all exposure times, but only in traces with respect to the prevailing amounts of MT-I/II isoforms. So induction can be attributed to isoform I/II only.
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123
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Abstract
In this study we compared indicators of Cd bioavailability (water extracts, Lakanen extracts, free ions) and ecotoxicity in forest soils with contrasting physico-chemical characteristics. Soil samples were treated with CdCl(2) solutions (0, 0.1, 1, 10 and 100 mM) and incubated for 30 days. Microbial activity indexes (acid phosphatase, beta-glucosidase, basal respiration) and changes in bacterial community structure using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting were investigated. The Cd concentrations measured ranged from 1% to 37% of the total additions in water extracts, to higher levels in Lakanen extracts. Effects of Cd were observed at bioavailable concentrations exceeding United Nations/European Economic Commission UN/ECE guidelines for total Cd in the soil solution. Basal respiration was the most affected index, while enzymatic activities showed variable responses to the Cd treatments. We also noticed that soils with pH higher than 6.7 and clay content higher than 50% showed inhibition of basal respiration but no marked shift in bacterial community structure. Soils with lower pH (pH <5.8) with less clay content (<50%) showed in addition strong changes in the bacterial community structure. Our results provide evidence for the importance of relating the effects of Cd on the soil communities to soil properties and to bioavailability.
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Affiliation(s)
- Anna Lazzaro
- Soil Ecology, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
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124
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Williams TD, Diab AM, George SG, Godfrey RE, Sabine V, Conesa A, Minchin SD, Watts PC, Chipman JK. Development of the GENIPOL European flounder (Platichthys flesus) microarray and determination of temporal transcriptional responses to cadmium at low dose. Environ Sci Technol 2006; 40:6479-88. [PMID: 17120584 DOI: 10.1021/es061142h] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We have constructed a high density, 13 270-clone cDNA array for the sentinel fish species European flounder (Platichthys flesus), combining clones from suppressive subtractive hybridization and a liver cDNA library; DNA sequences of 5211 clones were determined. Fish were treated by single intraperitoneal injection with 50 micrograms cadmium chloride per kilogram body weight, a dose relevant to environmental exposures, and hepatic gene expression changes were determined at 1, 2, 4, 8, and 16 days postinjection in comparison to saline-treated controls. Gene expression responses were confirmed by real-time reverse transcription polymerase chain reaction (RT-PCR). Blast2GO gene ontology analysis highlighted a general induction of the unfolded protein response, response to oxidative stress, protein synthesis, transport, and degradation pathways, while apoptosis, cell cycle, cytoskeleton, and cytokine genes were also affected. Transcript levels of cytochrome P450 1A (CYP1A) were repressed and vitellogenin altered, real-time PCR showed induction of metallothionein. We thus describe the establishment of a useful resource for ecotoxicogenomics and the determination of the temporal molecular responses to cadmium, a prototypical heavy metal pollutant.
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Affiliation(s)
- Tim D Williams
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, B15 2TT UK.
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125
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Kanevsky N, Dascal N. Regulation of maximal open probability is a separable function of Ca(v)beta subunit in L-type Ca2+ channel, dependent on NH2 terminus of alpha1C (Ca(v)1.2alpha). ACTA ACUST UNITED AC 2006; 128:15-36. [PMID: 16801381 PMCID: PMC2151559 DOI: 10.1085/jgp.200609485] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
β subunits (Cavβ) increase macroscopic currents of voltage-dependent Ca2+ channels (VDCC) by increasing surface expression and modulating their gating, causing a leftward shift in conductance–voltage (G-V) curve and increasing the maximal open probability, Po,max. In L-type Cav1.2 channels, the Cavβ-induced increase in macroscopic current crucially depends on the initial segment of the cytosolic NH2 terminus (NT) of the Cav1.2α (α1C) subunit. This segment, which we term the “NT inhibitory (NTI) module,” potently inhibits long-NT (cardiac) isoform of α1C that features an initial segment of 46 amino acid residues (aa); removal of NTI module greatly increases macroscopic currents. It is not known whether an NTI module exists in the short-NT (smooth muscle/brain type) α1C isoform with a 16-aa initial segment. We addressed this question, and the molecular mechanism of NTI module action, by expressing subunits of Cav1.2 in Xenopus oocytes. NT deletions and chimeras identified aa 1–20 of the long-NT as necessary and sufficient to perform NTI module functions. Coexpression of β2b subunit reproducibly modulated function and surface expression of α1C, despite the presence of measurable amounts of an endogenous Cavβ in Xenopus oocytes. Coexpressed β2b increased surface expression of α1C approximately twofold (as demonstrated by two independent immunohistochemical methods), shifted the G-V curve by ∼14 mV, and increased Po,max 2.8–3.8-fold. Neither the surface expression of the channel without Cavβ nor β2b-induced increase in surface expression or the shift in G-V curve depended on the presence of the NTI module. In contrast, the increase in Po,max was completely absent in the short-NT isoform and in mutants of long-NT α1C lacking the NTI module. We conclude that regulation of Po,max is a discrete, separable function of Cavβ. In Cav1.2, this action of Cavβ depends on NT of α1C and is α1C isoform specific.
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Affiliation(s)
- Nataly Kanevsky
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel
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126
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Gauley J, Heikkila JJ. Examination of the expression of the heat shock protein gene, hsp110, in Xenopus laevis cultured cells and embryos. Comp Biochem Physiol A Mol Integr Physiol 2006; 145:225-34. [PMID: 16861019 DOI: 10.1016/j.cbpa.2006.06.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 06/16/2006] [Accepted: 06/19/2006] [Indexed: 10/24/2022]
Abstract
Eukaryotic organisms respond to various stresses with the synthesis of heat shock proteins (HSPs). HSP110 is a large molecular mass HSP that is part of the HSP70/DnaK superfamily. In this study, we have examined, for the first time, the expression of the hsp110 gene in Xenopus laevis cultured cells and embryos. Sequence analysis revealed that the protein encoded by the hsp110 cDNA exhibited 74% identity with its counterparts in mammals and only 27-29% with members of the Xenopus HSP70 family. Hsp110 mRNA and/or protein was detected constitutively in A6 kidney epithelial cells and was inducible by heat shock, sodium arsenite, and cadmium chloride. However, treatment with ethanol or copper sulfate had no detectable effect on hsp110 mRNA levels. Similar results were obtained for hsp70 mRNA except that it was inducible with ethanol. In Xenopus embryos, hsp110 mRNA was present constitutively during development. Heat shock-inducible accumulation of hsp110 mRNA occurred only after the midblastula stage. Whole mount in situ hybridization analysis revealed that hsp110 mRNA accumulation in control and heat shocked embryos was enriched in selected tissues. These studies demonstrate that Xenopus hsp110 gene expression is constitutive and stress inducible in cultured cells and developmentally- and tissue specifically-regulated during early embryogenesis.
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Affiliation(s)
- Julie Gauley
- Department of Biology, University of Waterloo, Waterloo, Canada ON N2L 3G1
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127
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Silva E, Lopez-Espinosa MJ, Molina-Molina JM, Fernández M, Olea N, Kortenkamp A. Lack of activity of cadmium in in vitro estrogenicity assays. Toxicol Appl Pharmacol 2006; 216:20-8. [PMID: 16716372 DOI: 10.1016/j.taap.2006.04.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 03/30/2006] [Accepted: 04/03/2006] [Indexed: 11/22/2022]
Abstract
Prompted by reports about strong estrogenic effects of cadmium, attempts were made to reproduce these observations using the yeast estrogen screen (YES) and the E-Screen assays. For the first time, possible activation of the Src/MAPK pathway was also investigated. In the YES, only a slight activation (10% of a maximal effect) of the estrogen receptor alpha (ERalpha) was observed at cadmium concentrations between 5 x 10(-7) M and 5 x 10(-6) M. In the E-Screen assay, carried out by two laboratories, the heavy metal was without observable cell proliferative effects when tested in the range between 6 x 10(-11) M and 1 x 10(-5) M. However, in both assays, cadmium led to a reduction of the effects of 17beta-estradiol (E2). Treatment of MCF-7 human breast cancer cells with 1 x 10(-7) M cadmium failed to induce phosphorylation of Src and the MAP kinases Erk1 and Erk2-effects shown to occur with E2 and epidermal growth factor (EGF). In summary, we were unable to confirm the strong estrogenicity of cadmium reported recently by a number of laboratories. This apparent absence of effects in our hands is not due to a lack of uptake of the metal or to effective protection against cadmium by high levels of glutathione or metallothionein, since toxicity and an antagonism of E2 responses were observed both in the YES and the E-Screen.
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Affiliation(s)
- Elisabete Silva
- Centre for Toxicology, School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
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128
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Polo-Parada L, Chan SA, Smith C. An activity-dependent increased role for L-type calcium channels in exocytosis is regulated by adrenergic signaling in chromaffin cells. Neuroscience 2006; 143:445-59. [PMID: 16962713 DOI: 10.1016/j.neuroscience.2006.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 07/31/2006] [Accepted: 08/01/2006] [Indexed: 11/16/2022]
Abstract
Chromaffin cells of the adrenal medulla represent a primary output of the sympathetic nervous system. Their electrical stimulation evokes the fusion of large dense core granules with the cell membrane and the exocytic release of multiple transmitter molecules into the circulation. There the transmitters contribute to the regulation of basic metabolism of the organism. Under physiological activity, granule fusion and transmitter release are limited by activity-dependent Ca(2+) influx, entering through multiple isoforms of voltage-gated calcium channels. In this study we utilize perforated-patch voltage-clamp recordings and depolarize mouse chromaffin cells in situ with action potential-like waveforms to mimic physiological firing. We measure calcium influx through specific isoforms and measure cell capacitance as an index of granule fusion. Combining these approaches we calculate specific stimulus-secretion efficiencies for L-type, N-type, P/Q-type and R-type calcium channels under varied physiological activity levels. Current influx through all channel subtypes exhibited an activity-dependent depression. As expected P/Q-type channels, while responsible for modest Ca(2+) influx, are tightly coupled to catecholamine secretion under all conditions. We further find that stimulation designed to match sympathetic input under the acute stress response recruits L-type channels to a state of enhanced stimulus-secretion efficiency. N- and R-type channels do not undergo activity-dependent recruitment and remain loosely coupled to the secretion. Thus, only L-type channels exhibit activity-dependent changes in their stimulus-secretion function under physiological stimulation. Lastly, we show that treatment with the beta-adrenergic agonist, isoproterenol, specifically blocks the increase in the stimulus-secretion function of L-type channels. Thus, increased cell firing specifically enhances stimulus-secretion coupling of L-type Ca(2+) channels in chromaffin cells in situ. This mechanism is regulated by an adrenergic signaling pathway.
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Affiliation(s)
- L Polo-Parada
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH 44106, USA
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129
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Podazza G, Rosa M, González JA, Hilal M, Prado FE. Cadmium induces changes in sucrose partitioning, invertase activities, and membrane functionality in roots of Rangpur lime (Citrus limonia L. Osbeck). Plant Biol (Stuttg) 2006; 8:706-14. [PMID: 16883481 DOI: 10.1055/s-2006-924171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Cadmium (Cd) uptake effects on sucrose content, invertase activities, and plasma membrane functionality were investigated in Rangpur lime roots ( CITRUS LIMONIA L. Osbeck). Cadmium accumulation was significant in roots but not in shoots and leaves. Cadmium produced significant reduction in roots DW and increment in WC. Leaves and shoots did not show significant differences on both parameters. Sucrose content was higher in control roots than in Cd-exposed ones. Apoplastic sucrose content was much higher in Cd-exposed roots than in control ones. Cd-exposed roots showed a significant decrease in both cell wall-bound and cytoplasmic (neutral) invertase activities; while the vacuolar isoform did not show any change. Alterations in lipid composition and membrane fluidity of Cd-exposed roots were also observed. In Cd-exposed roots phospholipid and glycolipid contents decreased about 50 %, while sterols content was reduced about 22 %. Proton extrusion was inhibited by Cd. Lipid peroxidation and proton extrusion inhibition were also detected by histochemical analysis. This work's findings demonstrate that Cd affects sucrose partitioning and invertase activities in apoplastic and symplastic regions in Rangpur lime roots as well as the plasma membrane functionality and H (+)-ATPase activity.
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Affiliation(s)
- G Podazza
- Fundación Miguel Lillo, Area Botánica. Miguel Lillo 251 CP 4000 Tucumán, Argentina
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130
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Janer A, Martin E, Muriel MP, Latouche M, Fujigasaki H, Ruberg M, Brice A, Trottier Y, Sittler A. PML clastosomes prevent nuclear accumulation of mutant ataxin-7 and other polyglutamine proteins. ACTA ACUST UNITED AC 2006; 174:65-76. [PMID: 16818720 PMCID: PMC2064165 DOI: 10.1083/jcb.200511045] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The pathogenesis of spinocerebellar ataxia type 7 and other neurodegenerative polyglutamine (polyQ) disorders correlates with the aberrant accumulation of toxic polyQ-expanded proteins in the nucleus. Promyelocytic leukemia protein (PML) nuclear bodies are often present in polyQ aggregates, but their relation to pathogenesis is unclear. We show that expression of PML isoform IV leads to the formation of distinct nuclear bodies enriched in components of the ubiquitin-proteasome system. These bodies recruit soluble mutant ataxin-7 and promote its degradation by proteasome-dependent proteolysis, thus preventing the aggregate formation. Inversely, disruption of the endogenous nuclear bodies with cadmium increases the nuclear accumulation and aggregation of mutant ataxin-7, demonstrating their role in ataxin-7 turnover. Interestingly, β-interferon treatment, which induces the expression of endogenous PML IV, prevents the accumulation of transiently expressed mutant ataxin-7 without affecting the level of the endogenous wild-type protein. Therefore, clastosomes represent a potential therapeutic target for preventing polyQ disorders.
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Affiliation(s)
- Alexandre Janer
- Institut National de la Santé et de la Recherche Médicale U679, Neurologie et Thérapeutique Expérimentale, 75651 Paris Cedex 13, France.
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131
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Kita K, Miura N, Yoshida M, Yamazaki K, Ohkubo T, Imai Y, Naganuma A. Potential effect on cellular response to cadmium of a single-nucleotide A --> G polymorphism in the promoter of the human gene for metallothionein IIA. Hum Genet 2006; 120:553-60. [PMID: 16927099 DOI: 10.1007/s00439-006-0238-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Accepted: 07/25/2006] [Indexed: 10/24/2022]
Abstract
Most people generally ingest cadmium in their food. Cadmium that has accumulated in tissues induces the synthesis of metallothioneins (MTs) which are metal-binding proteins that bind tightly to cadmium to inhibit its renal toxicity. Individuals whose ability to induce the synthesis of MTs is low seem likely to be particularly susceptible to the toxic effects of cadmium. In this study, we analyzed the polymorphism of the promoter region of the gene for MT-IIA, the major species of MT in humans, in 119 adult Japanese subjects. We found that about 18% of the subjects had an A --> G single-nucleotide polymorphism in the core region of the promoter near the TATA box. A reporter-gene assay using HEK293 cells showed that replacement of A by G at position -5 reduced the efficiency of the cadmium-induced transcription of the gene for MT-IIA. This single-nucleotide polymorphism inhibited the binding of nuclear proteins to the core promoter region of the gene for MT-IIA. When the promoter region upstream of the TATA box was replaced by a sequence that contained three dioxin-responsive elements, the reporter-gene assay demonstrated that the A --> G single-nucleotide polymorphism resulted in a marked reduction in the rate of dioxin-induced transcription. These results suggest that the A --> G single-nucleotide polymorphism reduces the efficiency of those aspects of the transcription of the gene for MT-IIA that are controlled by general transcription factors.
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Affiliation(s)
- Kayoko Kita
- Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
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132
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Chen Q, Pan HL. Regulation of synaptic input to hypothalamic presympathetic neurons by GABA(B) receptors. Neuroscience 2006; 142:595-606. [PMID: 16887273 DOI: 10.1016/j.neuroscience.2006.06.039] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 06/21/2006] [Accepted: 06/22/2006] [Indexed: 02/02/2023]
Abstract
The hypothalamic paraventricular (PVN) neurons projecting to the spinal cord and brainstem play an important role in the control of homeostasis and the sympathetic nervous system. Although GABA(B) receptors are present in the PVN, their function in the control of synaptic inputs to PVN presympathetic neurons is not clear. Using retrograde tracing and whole-cell patch-clamp recordings in rat brain slices, we determined the role of presynaptic GABA(B) receptors in regulation of glutamatergic and GABAergic inputs to spinally projecting PVN neurons. The GABA(B) receptor agonist baclofen (1-50 microM) dose-dependently decreased the frequency but not the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) and inhibitory postsynaptic currents (sIPSCs). The effect of baclofen on sEPSCs and sIPSCs was completely blocked by 10 microM CGP52432, a selective GABA(B) receptor antagonist. Baclofen also significantly reduced the frequency of both miniature excitatory and miniature inhibitory postsynaptic currents (mEPSCs and mIPSCs). Furthermore, uncoupling pertussis toxin-sensitive G(i/o) proteins with N-ethylmaleimide abolished baclofen-induced inhibition of mEPSCs and mIPSCs. However, the inhibitory effect of baclofen on the frequency of mIPSCs and mEPSCs persisted in the presence of either Cd2+, a voltage-gated Ca2+ channel blocker, or 4-aminopyridine, a blocker of voltage-gated K+ channels. Our results suggest that activation of presynaptic GABA(B) receptors inhibits synaptic GABA and glutamate release to PVN presympathetic neurons. This presynaptic action of GABA(B) receptors is mediated by the N-ethylmaleimide-sensitive G(i/o) proteins, but independent of voltage-gated Ca2+ and K+ channels.
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Affiliation(s)
- Q Chen
- Department of Anesthesiology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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133
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Wu CC, Gardarin A, Catty P, Guillain F, Mintz E. CadA, the Cd2+-ATPase from Listeria monocytogenes, can use Cd2+ as co-substrate. Biochimie 2006; 88:1687-92. [PMID: 16889884 DOI: 10.1016/j.biochi.2006.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Accepted: 06/18/2006] [Indexed: 10/24/2022]
Abstract
CadA is a membrane protein of the P-type ATPase family which is the major determinant of the resistance to Cd2+ in Listeria monocytogenes. During its catalytic cycle, CadA undergoes auto-phosphorylation from ATP at Asp398, which allows Cd2+ translocation across the membrane. In the reverse mode, Asp398 is phosphorylated from Pi. From the data obtained so far, the CadA catalytic mechanism is similar to that proposed for the sarcoplasmic reticulum Ca2+-ATPase, the model of the P-type ATPase family. We show here that CadA is sensitive to two different ranges of Cd2+ concentration. The 0.1-10 microM range of added CdCl2 corresponds to Cd2+ binding at the transport site of unphosphorylated CadA which induces the reaction of the enzyme with ATP and impairs its reaction with Pi. The 0.1-1 mM range of added CdCl2 could correspond to Cd2+ binding to the transport site accessible from the extracellular medium. In addition, although it is widely accepted that the actual substrate of P-type ATPases is the MgATP complex, we show here that CadA can also perform its cycle in the absence of Mg2+, using CdATP in the place of MgATP at the catalytic site.
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Affiliation(s)
- C C Wu
- CEA, DSV, DRDC, Laboratoire de Biophysique Moléculaire et Cellulaire, UMR 5090 CEA-CNRS-Université Joseph-Fourier, 17, rue des Martyrs, 38054 Grenoble cedex 9, France
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134
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Bellamy J, Bowen EJ, Russo AF, Durham PL. Nitric oxide regulation of calcitonin gene-related peptide gene expression in rat trigeminal ganglia neurons. Eur J Neurosci 2006; 23:2057-66. [PMID: 16630053 PMCID: PMC1486900 DOI: 10.1111/j.1460-9568.2006.04742.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Calcitonin gene-related peptide (CGRP) and nitric oxide are involved in the underlying pathophysiology of migraine and other diseases involving neurogenic inflammation. We have tested the hypothesis that nitric oxide might trigger signaling mechanisms within the trigeminal ganglia neurons that would coordinately stimulate CGRP synthesis and release. Treatment of primary trigeminal ganglia cultures with nitric oxide donors caused a greater than four-fold increase in CGRP release compared with unstimulated cultures. Similarly, CGRP promoter activity was also stimulated by nitric oxide donors and overexpression of inducible nitric oxide synthase (iNOS). Cotreatment with the antimigraine drug sumatriptan greatly repressed nitric oxide stimulation of CGRP promoter activity and secretion. Somewhat surprisingly, the mechanisms of nitric oxide stimulation of CGRP secretion did not require cGMP or PI3-kinase signaling pathways, but rather, nitric oxide action required extracellular calcium and likely involves T-type calcium channels. Furthermore, nitric oxide was shown to increase expression of the active forms of the mitogen-activated protein kinases Jun amino-terminal kinase and p38 but not extracellular signal-related kinase in trigeminal neurons. In summary, our results provide new insight into the cellular mechanisms by which nitric oxide induces CGRP synthesis and secretion from trigeminal neurons.
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Affiliation(s)
- Jamie Bellamy
- Department of Biology, 225 Temple Hall, Missouri State University, Springfield, MO 65897, USA
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135
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Estévez-Hernández O, Otazo-Sánchez E, de Cisneros JLHH, Naranjo-Rodríguez I, Reguera E. Novel CdCl2 and HgCl2 complexes with 3-monosubstituted and 3,3-disubstituted 1-furoylthioureas: IR and Raman spectra. Spectrochim Acta A Mol Biomol Spectrosc 2006; 64:961-71. [PMID: 16330247 DOI: 10.1016/j.saa.2005.09.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Accepted: 09/06/2005] [Indexed: 05/05/2023]
Abstract
Two series of coordination complexes of CdCl(2) and HgCl(2) with 3-monosubstituted and 3,3-disubstituted 1-furoylthioureas were prepared and characterized. These complexes were obtained with a medium to high yield from ethanolic solutions of both ligand and salt. The formed complex results from the salt-ligand interaction with participation of both the salt anion and cation. Information on the coordination chemistry of these complexes was derived from thermal stability data, and IR, Raman and (13)C CPMAS NMR spectra. On coordination the electronic structure of these ligands changes as a whole, affecting practically all their vibrational pattern, however, within that complex pattern some vibrations provide valuable information on the nature of the studied complexes. These thiourea derivatives behave as neutral ligands, which coordinate the metal ion through the sulfur atom of the thiocarbonyl group. This fact is supported by the observed frequency shift, to lower values, in the nu(CS) vibration on the coordination and the appearance of a low frequency Raman line which was assigned to the metal-sulfur stretching, nu(M-S), in the formed complex. The frequency of the nu(CO) vibration always increases on complex formation, which discards the participation of the carbonyl group in the coordination process. The complexation takes place preserving the free ligand conformation, established from intra-molecular interactions, particularly in 3-monosubstituted ligands. Such features of the studied ligands and their complexes are also supported by (13)C CPMAS NMR spectra. This spectroscopic information correlates with the reported behavior of the ligands in ion selective electrodes.
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Affiliation(s)
- O Estévez-Hernández
- Instituto de Materiales y Reactivos (IMRE), Universidad de la Habana, San Lázaro s/n, Vedado, 10400 La Habana, Cuba
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136
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Zhukalin M, Blanksma MK, Silva TD, Suyehira SW, Harvey WA, Heggland SJ, Craig PR. Characterization and in vitro Cytotoxicity Testing of Ethanolamine-derived Cadmium Chelating Agents. Biometals 2006; 20:61-72. [PMID: 16758114 DOI: 10.1007/s10534-006-9015-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Accepted: 04/11/2006] [Indexed: 11/24/2022]
Abstract
We have synthesized and characterized the new cadmium chelating agent potassium bis(2-hydroxyethyl)aminoethyldithiocarbonate hemihydrate, K[bhexan] x 0.5H2O (2), that is structurally related to the known effective in vivo cadmium chelating agent potassium bis(2-hydroxyethyl)dithiocarbamate, K[bhedtc] (1). The corresponding cadmium complex of 2 differs from di(bis(2-hydroxyethyl)dithiocarbamato)cadmium(II), Cd(bhedtc)2 (3), in that the insoluble compound exhibits an elemental composition consistent with a cadmium:ligand ratio of 2:1. The cytotoxicity of the 1-3 was investigated using the human osteoblast-like cell line, Saos-2. Compounds 1 or 2 did not affect cell adherence or cell viability in the 100-500 microM concentration range studied, whereas 3 resulted in a concentration-dependent increase in loss of cell adherence and decrease in cell viability. Overall, the results of the loss of cell adherence, trypan blue exclusion and MTT assays showed that administration of 3 (cadmium complex of 1) resulted in cytotoxicity lower than that of cadmium chloride, but higher than that of the chelator 1 alone. The effect of simultaneous addition of cadmium chloride and 1 or 2 on cell viability was also assessed using the MTT assay. For the 100 microM cadmium chloride experiments, cell viability comparable to control cells was achieved for both 1 and 2 in the 100-500 microM concentration range studied. Cell viability comparable to control cells was achieved for 1 but not 2 in the 100-500 microM concentration range studied for the 200 microM cadmium chloride experiments. Thus 1 appears more effective than 2 in the ability to mediate the cytotoxic effects of cadmium in vitro upon concomitant administration.
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Affiliation(s)
- Mikhail Zhukalin
- Departments of Chemistry, Albertson College of Idaho, Caldwell, Idaho 83605-4432, USA
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137
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Wälchli C, Baumgartner S, Bastide M. Effect of Low Doses and High Homeopathic Potencies in Normal and Cancerous Human Lymphocytes: An In Vitro Isopathic Study. J Altern Complement Med 2006; 12:421-7. [PMID: 16813505 DOI: 10.1089/acm.2006.12.421] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVES Biologic effects of high homeopathic potencies can be studied in cell cultures using cell lines or primary cells. We hypothesized that primary cells would be more apt to respond to high potencies than cell lines, especially cancer cell lines. We set out to investigate the effects of low doses and high homeopathic potencies of cadmium chloride, respectively, in an intoxication model with human primary lymphocytes compared to a human leukemia cell line (Jurkat). DESIGN Cells were pretreated with either low concentrations (nM-microM) or high potencies (pool 15-20c) of cadmium for 120 hours, following which they were exposed to a toxic treatment with a range of cadmium concentrations (8-80 microM) during 24 hours. Cell viability was eventually assessed by use of the MTS/PES assay. Controls included a vehicle (NaCl 0.9%) for the low concentrations of cadmium or water 15-20c for cadmium 15-20c. A total of 34 experiments were conducted, 23 with low concentrations and 11 with high potencies of cadmium. Data were analyzed by analysis of variance. RESULTS Pretreatment with low concentrations or high potencies of cadmium significantly increased cell viability in primary lymphocytes after toxic challenge, compared to control cells (mean effect +/- standard error = 19% +/- 0.9% for low concentrations respectively 8% +/- 0.6% for high potencies of cadmium; p < 0.001 in both cases). The pretreatment effect of low doses was significant also in cancerous lymphocytes (4% +/- 0.5%; p < 0.001), albeit weaker than in normal lymphocytes. However, high homeopathic potencies had no effect on cancerous lymphocytes (1% +/- 1.9%; p = 0.45). CONCLUSIONS High homeopathic potencies exhibit a biologic effect on cell cultures of normal primary lymphocytes. Cancerous lymphocytes (Jurkat), having lost the ability to respond to regulatory signals, seem to be fairly unresponsive to high homeopathic potencies.
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Affiliation(s)
- Chantal Wälchli
- Institute for Complementary Medicine (KIKOM), University of Bern, Bern, Switzerland.
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138
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Abstract
Heme oxygenase (HO)-1 is the inducible isoform of the first and rate-controlling enzyme of heme degradation. HO-1 is up-regulated by a host of oxidative stress stimuli and has potent cytoprotective and anti-inflammatory functions via decreasing tissue levels of the prooxidant heme along with production of bilirubin and the signaling gas carbon monoxide. This review deals with recent findings that highlight the emerging significance of HO-1 in cardiovascular disease. Evidence is presented on how heme and various oxidative stress stimuli may cause endothelial cell dysfunction and how HO-1 may counteract the detrimental effects of oxidative stress in the endothelium. Recent advances in the understanding of the role of endothelial HO-1 for the regulation of the inflammatory response are summarized, including the modulation of leukocyte recruitment and transmigration through the endothelial barrier. Furthermore, experimental evidence from various cell culture and animal models is discussed which suggests an association of HO-1 with the complex sequence of events that cause atherosclerosis. In the second part of the review we present potential strategies that apply HO-1 as a therapeutic target in the treatment of cardiovascular disease. Specific inducers of HO-activity which may ultimately lead to the development of clinically relevant pharmacological applications are introduced.
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Affiliation(s)
- S Immenschuh
- Institute for Clinical Immunology and Transfusion Medicine, Justus-Liebig-University Giessen, Giessen, Germany.
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139
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Desouky MMA. Tissue distribution and subcellular localization of trace metals in the pond snail Lymnaea stagnalis with special reference to the role of lysosomal granules in metal sequestration. Aquat Toxicol 2006; 77:143-52. [PMID: 16413619 DOI: 10.1016/j.aquatox.2005.11.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2005] [Revised: 11/25/2005] [Accepted: 11/26/2005] [Indexed: 05/06/2023]
Abstract
The present study was undertaken to elucidate the cellular mechanisms, which govern metal sequestration and detoxification in gastropods. For this purpose the pond snail, Lymnaea stagnalis was exposed to environmentally relevant concentrations of three species of metals (Al, Zn and Cd) for 30 days and the localization and fate of these metals were followed in different tissues of the snails. The measurement of relative distribution of metals between tissues revealed that the digestive gland and kidney account for most of the accumulated metals. Al and Cd (non-essential metals) were redistributed to the digestive gland, possibly because of the presence of specific binding entities in the digestive glands of the herein species. This study focuses on the role of intracellular metal-containing granules on metal sequestration. Three main types of granules were identified in the digestive gland cells namely small, green and yellow granules. The morphological examination and the progressive accumulation of elements within these granules revealed that they are developmental stages with the yellow granule being the mature one. The total number of these granules was found to be significantly increased upon exposure of the snails to Al only. This increase may be a response to the large amount of Al that is accumulated through feeding route of this grazing snail. X-ray microanalysis (XRMA) revealed that metals were localized in all three types of digestive gland granules. The increased amount of ligands (P and S) in the granules may give evidence for their role in metal sequestration. Levels of Al and P were positively correlated in the digestive gland granules. It is possible that aluminium is bound to phosphorus to render it insoluble and so to both immobilize it within the lysosome and to be excreted in a highly insoluble form. On the other hand, both Zn and Cd induced marked upregulation of S in mature (yellow) granules by 26- and 11-folds, respectively. The lysosomal codeposition of S and either Cd or Zn in the lysosomal granules in addition to the increase in RER cisternae may indicate that the exposure to these metals could induce metallothionein synthesis in the cells. The microscopical examinations in the present study revealed that metal detoxification from the digestive gland cells may occur via faeces or via basal exocytosis towards hemocytes dispersed by the connective tissue in the visceral mass. In the kidney, one type of granules, the excretory concretions, was identified in the nephrocytes. The significant increase in the number of these concretions in the snail L. stagnalis upon exposure to metals may give further evidence for their role in metal excretion.
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140
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Lee MJ, Ayaki H, Goji J, Kitamura K, Nishio H. Cadmium restores in vitro splicing activity inhibited by zinc-depletion. Arch Toxicol 2006; 80:638-43. [PMID: 16645842 DOI: 10.1007/s00204-006-0104-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2006] [Accepted: 03/30/2006] [Indexed: 11/28/2022]
Abstract
Zinc (Zn)-depletion inhibits the second step of RNA splicing, namely exon-ligation. To investigate the effects of cadmium (Cd) and other metal ions on RNA splicing inhibited by Zn-depletion, we measured in vitro splicing activities in the presence of these metals. Zn-depletion in the splicing reaction mixture was achieved by addition of a Zn-chelator, 1,10-phenanthroline. Cd(II) at 1, 5 and 10 microM restored the splicing activity to 2, 24 and 72% of that in the control reaction mixture, while higher concentrations of Cd(II) decreased the splicing activity, and more than 50 microM Cd(II) showed a complete absence of spliced products. Hg(II) also restored the splicing activity, albeit to a lesser extent, since 5 and 10 microM Hg(II) restored the splicing activity to 3 and 4% of the control value. The other metal ions examined in this study, Co(II), Cu(II), Mg(II) and Mn(II), did not show any restoration of the splicing activity. We concluded that Cd(II) could restore the in vitro splicing activity inhibited by Zn-depletion, although higher concentrations of Cd(II) prevented progress of the RNA splicing reaction. These results suggest that Cd(II) has a bifunctional property regarding RNA splicing, and is stimulatory at low concentrations and inhibitory at high concentrations.
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Affiliation(s)
- Myeong Jin Lee
- Department of Public Health, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
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141
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Ben Ammar W, Nouairi I, Tray B, Zarrouk M, Jemall F, Ghorbel MH. [Cadmium effects on mineral nutrition and lipid contents in tomato leaves]. ACTA ACUST UNITED AC 2006; 199:157-63. [PMID: 16485602 DOI: 10.1051/jbio:2005016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The treatment of growing tomato (Lycopersicum esculentum) plants with CdCl2 (0, 1, 5, 10, 25 et 50 microM) on various plant physiological parameters and membrane lipids of primary and young leaves was studied. In leaves of tomato plants Cd produced a significant inhibition of growth, chlorophyll content and alteration of the nutrient status in both primary and young leaves. A decrease in lipid contents, specially galactolipids and phospholipids, was observed after Cd treatment.
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Affiliation(s)
- W Ben Ammar
- Unité de Recherche de Nutrition et Métabolisme Azotés et Protéines de Stress, 99 UR/0920, Faculté des Sciences de Tunis, 1060 Tunis, Tunisie
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142
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Nasif FJ, Hu XT, White FJ. Repeated cocaine administration increases voltage-sensitive calcium currents in response to membrane depolarization in medial prefrontal cortex pyramidal neurons. J Neurosci 2006; 25:3674-9. [PMID: 15814798 PMCID: PMC6725383 DOI: 10.1523/jneurosci.0010-05.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The medial prefrontal cortex (mPFC) plays a critical role in cocaine addiction. However, evidence to elucidate how the mPFC is functionally involved in cocaine addiction remains incomplete. Recent studies have revealed that repeated cocaine administration induces various neuroadaptations in pyramidal mPFC neurons, including a reduction in voltage-gated K+ currents (VGKCs) and a possible increase in voltage-sensitive Ca2+ currents (I(Ca)). Here, we performed both current-clamp recordings in brain slices and voltage-clamp recordings in freshly dissociated cells to determine whether I(Ca) is altered in mPFC pyramidal neurons after chronic cocaine treatment with a short-term or long-term withdrawal. In addition, a critical role of VGKCs in regulating the generation of Ca2+ plateau potential was also studied in mPFC neurons. Repeated cocaine administration significantly prolonged the duration of evoked Ca2+ plateau potentials and increased the whole-cell I(Ca) in mPFC neurons after a 3 d withdrawal. Selective blockade of L-type Ca2+ channels by nifedipine not only significantly increased the threshold but also reduced the duration and amplitude of Ca2+ plateau potentials in both saline- and cocaine-withdrawn mPFC neurons. However, there was no significant difference in the increased threshold, reduced duration, and decreased amplitude of Ca2+ potentials between saline- and cocaine-withdrawn neurons after blockade of L-type Ca2+ channels. Moreover, an increase in amplitude was also observed, whereas the prolonged duration persisted, in Ca2+ potentials after 2-3 weeks of withdrawal. These findings indicate that chronic exposure to cocaine facilitates the responsiveness of I(Ca), particularly via the activated L-type Ca2+ channels, to excitatory stimuli in rat mPFC pyramidal neurons.
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Affiliation(s)
- Fernando J Nasif
- Department of Cellular and Molecular Pharmacology, Rosalind Franklin University of Medicine and Science, The Chicago Medical School, North Chicago, Illinois 60064, USA
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143
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Leão RM, Kushmerick C, Pinaud R, Renden R, Li GL, Taschenberger H, Spirou G, Levinson SR, von Gersdorff H. Presynaptic Na+ channels: locus, development, and recovery from inactivation at a high-fidelity synapse. J Neurosci 2006; 25:3724-38. [PMID: 15814803 PMCID: PMC4511161 DOI: 10.1523/jneurosci.3983-04.2005] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Na+ channel recovery from inactivation limits the maximal rate of neuronal firing. However, the properties of presynaptic Na+ channels are not well established because of the small size of most CNS boutons. Here we study the Na+ currents of the rat calyx of Held terminal and compare them with those of postsynaptic cells. We find that presynaptic Na+ currents recover from inactivation with a fast, single-exponential time constant (24 degrees C, tau of 1.4-1.8 ms; 35 degrees C, tau of 0.5 ms), and their inactivation rate accelerates twofold during development, which may contribute to the shortening of the action potential as the terminal matures. In contrast, recordings from postsynaptic cells in brainstem slices, and acutely dissociated, reveal that their Na+ currents recover from inactivation with a double-exponential time course (tau(fast) of 1.2-1.6 ms; tau(slow) of 80-125 ms; 24 degrees C). Surprisingly, confocal immunofluorescence revealed that Na+ channels are mostly absent from the calyx terminal but are instead highly concentrated in an unusually long (approximately 20-40 microm) unmyelinated axonal heminode. Outside-out patch recordings confirmed this segregation. Expression of Na(v)1.6 alpha-subunit increased during development, whereas the Na(v)1.2alpha-subunit was not present. Serial EM reconstructions also revealed a long pre-calyx heminode, and biophysical modeling showed that exclusion of Na+ channels from the calyx terminal produces an action potential waveform with a shorter half-width. We propose that the high density and polarized locus of Na+ channels on a long heminode are critical design features that allow the mature calyx of Held terminal to fire reliably at frequencies near 1 kHz.
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Affiliation(s)
- Ricardo M Leão
- The Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239-3098, USA
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144
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Zasukhina GD, Vasil'eva IM, Vedernikov AI, Gromov SP, Alfimov MV. Antimutagenic characteristics of new diazacrown compounds with N-carboxyalkyl substitutes. Bull Exp Biol Med 2006; 141:331-3. [PMID: 17073152 DOI: 10.1007/s10517-006-0163-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Two new benzodiaza-15-crown-5 compounds containing two N-hydroxycarbonylmethyl or N-hydroxycarbonylpropyl substitutes were synthesized. The first of these compounds exhibited more pronounced protective effects towards human cells according to criteria of primary DNA injury and cell survival after exposure to gamma-radiation and CdCl2; by antimutagenic activity this compound was comparable to garlic extract. The antimutagenic effect of these compounds was realized not through the antioxidant mechanism.
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Affiliation(s)
- G D Zasukhina
- Institute of General Genetics, Russian Academy of Sciences, Moscow.
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145
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Pamidimukkala J, Habibi S, Hay M. Frequency-dependent depression of exocytosis and the role of voltage-gated calcium channels. Brain Res 2006; 1078:1-8. [PMID: 16492381 DOI: 10.1016/j.brainres.2006.01.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 01/09/2006] [Accepted: 01/16/2006] [Indexed: 10/25/2022]
Abstract
Synaptic vesicle exocytosis in primary cultures of baroreceptor neurons is reduced during high-frequency stimulation. Calcium influx through voltage-gated calcium channels (VGCC) is a key step in neurotransmitter release. With the help of FM2-10, a marker of synaptic vesicle recycling, the present study investigates the differential contribution of several VGCC subtypes to exocytosis in neuronal processes and how this contribution is altered at high frequencies. In control experiments, field stimulation at 0.5 Hz evoked about 66 +/- 5% destaining. Combined blockade of N- and P/Q-subtypes with Ctx-MVIIC was far more effective in reducing exocytosis (11 +/- 8%) than blocking N-type (49 +/- 5%, Ctx-GVIA) or P-type (46 +/- 1%, Agatoxin) alone. The effectiveness of the blockers also varied with the duration of stimulation: Ctx-GVIA attenuating exocytosis significantly in the first 60 s and Agatoxin affecting exocytosis only towards the end of 180 s stimulation period. Field stimulation at 10 Hz evoked exocytosis (36 +/- 18%) comparable to that evoked by 0.5 Hz in the presence of Ctx-GVIA. While blockade with Agatoxin had no effects, Ctx-GVIA, Ctx-MVIIC and L-type blocker Nifedepine had small but similar inhibitory effects on exocytosis at 10 Hz. The data suggest that N-type is the major contributor to exocytosis at 0.5 Hz, and this contribution is reduced during prolonged stimulation periods and at high frequencies.
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Affiliation(s)
- Jaya Pamidimukkala
- Dalton Cardiovascular Research Center, 134 Research Park, University of Missouri, Columbia, MO 65211, USA.
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146
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Engelman HS, Anderson RL, Daniele C, Macdermott AB. Presynaptic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors modulate release of inhibitory amino acids in rat spinal cord dorsal horn. Neuroscience 2006; 139:539-53. [PMID: 16472927 DOI: 10.1016/j.neuroscience.2005.12.038] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Revised: 12/20/2005] [Accepted: 12/22/2005] [Indexed: 11/23/2022]
Abstract
Local inhibition within the spinal cord dorsal horn is mediated by the neurotransmitters GABA and glycine and strongly influences nociceptive and temperature signaling. Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are expressed by inhibitory interneurons and have been shown to modulate GABA release in other regions of the CNS. In the spinal cord, there is morphological evidence for presynaptic AMPA receptor subunits in GABAergic dorsal horn neurons, but functional data are lacking. To determine if AMPA receptors are indeed functional at presynaptic terminals of inhibitory neurons, we recorded evoked and miniature inhibitory postsynaptic currents (mIPSPs) in the superficial dorsal horn of the rat spinal cord. We show that AMPA receptor activation enhances spontaneous release of inhibitory amino acids in the presence of tetrodotoxin onto both lamina II neurons and NK1 receptor-expressing (NK1R+) lamina I neurons. This effect is sensitive to the concentration of extracellular Ca2+, yet is not fully blocked in most neurons in the presence of Cd2+, suggesting possible Ca2+ entry through AMPA receptors. Postsynaptic Ca2+ elevation is not required for these changes. AMPA-induced increases in mIPSP frequency are also seen in more mature dorsal horn neurons, indicating that these receptors may play a role in nociceptive processing in the adult. In addition, we have observed AMPA-induced depression of evoked release of GABA and glycine onto lamina I NK1R+ neurons. Taken together these data support a role for presynaptic AMPA receptors in modulating release of GABA and glycine in the superficial dorsal horn. Because inhibition in the dorsal horn is important for controlling pain signaling, presynaptic AMPA receptors acting to modulate the inhibitory inputs onto dorsal horn neurons would be expected to impact upon pain signaling in the spinal cord dorsal horn.
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Affiliation(s)
- H S Engelman
- Department of Physiology and Cellular Biophysics and the Center for Neurobiology and Behavior, Columbia University, 630 West 168th Street, New York, NY 10032, USA
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147
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Abstract
The purpose of this study was to demonstrate the cellular localization of cyclooxygenase-2 (COX-2) and caveolin-3 (Cav-3) in primarily cultured rat chondrocytes. In normal rat chondrocytes, we observed relatively high levels of Cav-3 and a very low level of COX-2 mRNA and protein. Upon treating the chondrocytes with 5 microM of CdCl(2) (Cd) for 6 hr, the expressions of COX-2 mRNA and protein were increased with the decreased Cav-3 mRNA and protein expressions. The detergent insoluble caveolae-rich membranous fractions that were isolated from the rat chondrocytes and treated with Cd contained the both proteins of both COX-2 and Cav-3 in a same fraction. The immuno-precipitation experiments showed complex formation between the COX-2 and Cav-3 in the rat chondrocytes. Purified COX-2 with glutathione S-transferase-fused COX-2 also showed complex formation with Cav-3. Confocal and electron microscopy also demonstrated the co-localization of COX-2 and Cav-3 in the plasma membrane. The results from our current study show that COX-2 and Cav-3 are co-localized in the caveolae of the plasma membrane, and they form a protein-protein complex. The co-localization of COX-2 with Cav-3 in the caveolae suggests that the caveolins might play an important role for regulating the function of COX-2.
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Affiliation(s)
- Jin-Oh Kwak
- Department of Pharmacology and Toxicology, College of Medicine, Inha University, Incheon, Korea
| | - Woon Kyu Lee
- Department of Laboratory Animal, Medical Research Center, College of Medicine, Yonsei University, Seoul, Korea
| | - Hyun-Woo Kim
- Department of Pharmacology and Toxicology, College of Medicine, Inha University, Incheon, Korea
| | - Sun-Mi Jung
- Department of Biological Engineering, College of Medicine, Inha University, Incheon, Korea
| | - Kwang-Jin Oh
- Department of Pharmacology and Toxicology, College of Medicine, Inha University, Incheon, Korea
| | - Sang-Yong Jung
- Laboratory of Molecular Neuroscience, Department of Life Science, POSTECH, Pohang, Korea
| | - Yang Hoon Huh
- National Creative Research Initiative, Center for Secretory Granule Research, College of Medicine, Inha University, Incheon, Korea
| | - Seok Ho Cha
- Department of Pharmacology and Toxicology, College of Medicine, Inha University, Incheon, Korea
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148
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Abstract
Currents contributing repolarization in rabbit ventricular myocytes are very complex because the I(to.s) covers almost the whole repolarization phase of the action potential. The other components of repolarizing currents, such as I(Kr) and I(Ks), are small. In the present work, with whole-cell patch-clamp technique, a clear evidence was provided for the existence of a hitherto unreported, voltage-dependent, nonselective cation current (NSCC) in rabbit ventricular myocytes. Na(+), K(+), and Cs(+) can permeate through the nonselective cation channel and the NSCC can be blocked by Gd(3+). The channels are sensitive to Ca(2+), Mg(2+)-free, and insulin in bathing solution. Activation of NSCC may provide complex effects on action potential configuration depending on the basal conditions and the experimental situations. Considering the voltage dependence and rapid activation kinetics of this current, we speculate that this current can provide an important influence on all repolarization phases of the action potential as well as contribute to the resting membrane potential in rabbit ventricular myocytes. In addition, it is conceivable that, under certain pathophysiological conditions (e.g., ischemia or excessive mechanical stress), the sensitivity of the channels could be altered in such a way that the conductance opens even in the presence of physiological Ca(2+), Mg(2+), and insulin. It might be an important factor on the repolarization of the action potential. Changes in NSCC may lead to an induction or inhibition of arrhythmia.
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Affiliation(s)
- Y-D Song
- Peking Union Medical College, National Research Institute for Family Planning, Beijing, China.
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149
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Abstract
The neurons in the external segment of the pallidum in the primate develop a characteristic firing pattern consisting of alternately occurring long, 2-20 s, strongly active phases and long completely silent phases when the subthalamo-pallidal excitatory inputs are blocked. The induction of the activity might be a factor in the development of dyskinesias after the loss of subthalamic output. In this study, we used globus pallidus (GPe) slice preparations obtained from juvenile rats to examined the conditions that support the alternatively occurring long depolarized and hyperpolarized phases which we refer to as the slow oscillation (SO). SO was not induced by the blockade of glutamatergic inputs but was induced by treatments that depolarized dendrites and, at the same time, hyperpolarized the somata with current injections. The treatments included elevation of extracellular K(+), application of K-current blockers and the lowering of extracellular Ca(2+). Application of TTX or intracellular BAPTA injection blocked the SO, while the SO could be maintained in hyperpolarization-activated inward current blockers, organic Ca-current blockers and up to 200 microm CdCl(2). These results suggest that Na currents play a major role in the generation of SO in vitro. It can be speculated that Na currents are involved in the development of active phases observed in the GPe after blockade of the glutamatergic inputs in vivo and that the unique property of GPe neurons in maintaining strong activity after the elimination of the glutamatergic driving force contributes to the development of motor disorders such as dyskinesia.
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Affiliation(s)
- Kenji Hashimoto
- Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, 855 Monroe Avenue, Memphis, TN 38163, USA
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Vallazza-Deschamps G, Cia D, Gong J, Jellali A, Duboc A, Forster V, Sahel JA, Tessier LH, Picaud S. Excessive activation of cyclic nucleotide-gated channels contributes to neuronal degeneration of photoreceptors. Eur J Neurosci 2006; 22:1013-22. [PMID: 16176343 DOI: 10.1111/j.1460-9568.2005.04306.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In different animal models, photoreceptor degeneration was correlated to an abnormal increase in cGMP concentration. The cGMP-induced photoreceptor toxicity was demonstrated by applying the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine on retinal explants. To assess the role of cGMP-gated channels in this cGMP toxicity, the Ca(2+) channel blockers verapamil and L- and D-diltiazem, which block cGMP-gated channels with different efficacies, were applied to in vitro animal models of photoreceptor degeneration. These models included: (i) adult rat retinal explants incubated with zaprinast, a more specific inhibitor of the rod phosphodiesterase than 3-isobutyl-1-methylxanthine and (ii) rd mouse retinal explants. Photoreceptor apoptosis was assessed by terminal dUTP nick end labelling and caspase 3 activation. Effects of the blockers on the synaptic rod Ca(2+) channels were measured by patch-clamp recording. In the zaprinast-induced photoreceptor degeneration model, both diltiazem isomers rescued photoreceptors whereas verapamil had no influence. Their neuroprotective efficacy was correlated to their inhibition of cGMP-gated channels (l-diltiazem>d-diltiazem>verapamil=0). In contrast, all three Ca(2+) channel blockers suppressed rod Ca(2+) channel currents similarly. This suppression of the currents by the diltiazem isomers was very weak (16.5%) at the neuroprotective concentration (10 microm). In rd retinal explants, both diltiazem isomers also slowed down rod degeneration in contrast to verapamil. L-diltiazem exhibited this effect at concentrations ranging from 1 to 20 microm. This study further supports the photoreceptor neuroprotection by diltiazem particularly in the rd mouse retina, whereas the absence of neuroprotection by verapamil further suggests the role of cGMP-gated channel activation in the induction of photoreceptor degeneration.
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Affiliation(s)
- Géraldine Vallazza-Deschamps
- Laboratoire de Physiopathologie Cellulaire et Moléculaire de la Rétine, INSERM U-592, Université Pierre et Marie Curie, Bâtiment Kourilsky 6ème étage, 75571 Paris Cedex 12, France
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