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Correia AT, Rebelo D, Marques J, Nunes B. Effects of the chronic exposure to cerium dioxide nanoparticles in Oncorhynchus mykiss: Assessment of oxidative stress, neurotoxicity and histological alterations. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2019; 68:27-36. [PMID: 30870693 DOI: 10.1016/j.etap.2019.02.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 01/24/2019] [Accepted: 02/21/2019] [Indexed: 06/09/2023]
Abstract
Cerium dioxide nanoparticles (CeO2-NPs) have a variety of uses, especially in the production of solar panels, oxygen pumps, gas sensors, computer chips and catalytic converters. Despite their worldwide use, the few published studies demonstrate that metallic nanoparticles, in general, are still not properly characterized in terms of their potencial ecotoxicological effects. CeO2-NPs, in particular, have demonstrated extreme antioxidant activity, but their in vivo toxicity is still unknown. This work intended to characterize the chronic toxicity (28 days) of three different ecologically relevant concentrations (0.1, 0.01, and 0.001 μg/L) of CeO2-NPs in the rainbow trout (Oncorhynchus mykiss), in terms of biomarkers of oxidative stress [activity of the enzymes glutathione S-transferases (GSTs) and catalase (CAT)] and neurotoxicity [activity of the enzyme acetylcholinesterase (AChE)], as well as histological alterations in liver and gills. In the hereby study, GSTs activity was increased in gills of fish exposed to the highest CeO2-NPs level. Moreover, a potential anti-oxidant response was also reported, with a significant increase of CAT activity observed in livers of the same fish. AChE, however, was not significantly altered in fish eyes. Individuals exposed to CeO2-NPs also presented marked changes in the gills (e.g. epithelial lifting, intercellular edema, lamellar hypertrophy and hyperplasia, secondary lamella fusion and aneurysms) and liver (e.g. hepatocyte vacuolization, pyknotic nucleus, enlargement of sinusoids and hyperemia). The semi-quantitative analysis (organs pathological index) also showed the establishment of a dose-effect relationship. Further studies about the ecotoxicological effects of the CeO2-NPs have yet to be conducted, considering their properties, as the aggregation chemistry and the ratio of its redox state, which may affect their availability to the organism and their toxicity in the environment and biota.
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Affiliation(s)
- A T Correia
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Rua dos Bragas 289, 4050-123 Porto, Portugal; Faculdade de Ciências da Saúde, Universidade Fernando Pessoa (UFP), Rua Carlos da Maia 296, 4200-150, Porto, Portugal
| | - D Rebelo
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Rua dos Bragas 289, 4050-123 Porto, Portugal; Departamento de Biologia, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - J Marques
- Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Rua dos Bragas 289, 4050-123 Porto, Portugal; Faculdade de Ciências da Saúde, Universidade Fernando Pessoa (UFP), Rua Carlos da Maia 296, 4200-150, Porto, Portugal
| | - B Nunes
- Departamento de Biologia, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; Centro de Estudos do Ambiente e do Mar (CESAM), Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
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Cree MG, Aarsland A, Herndon DN, Wolfe RR. Role of fat metabolism in burn trauma-induced skeletal muscle insulin resistance. Crit Care Med 2007; 35:S476-83. [PMID: 17713396 DOI: 10.1097/01.ccm.0000278066.05354.53] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Review current evidence on the role of fat in post-trauma insulin resistance, in reference to new studies with peroxisome proliferating activating receptor-alpha agonists. DESIGN Review. SETTING University laboratory. PATIENTS Thirty pediatric burn trauma patients. INTERVENTIONS Fourteen days of peroxisome proliferating activating receptor-alpha agonist immediately following burn trauma. MEASUREMENTS AND MAIN RESULTS We measured glucose metabolism and fat metabolism via tracer methodology and intracellular measurements. Insulin-stimulated glucose uptake is impaired following burn trauma, as is intracellular insulin signaling, palmitate oxidation, and mitochondrial oxidative capacity. Furthermore, levels of intracellular lipids are increased. Two weeks of peroxisome proliferating activating receptor-alpha treatment significantly reverses these pathologic changes incurred from burn injury. CONCLUSIONS Severe burn injury seriously affects multiple aspects of glucose and fat metabolism within the muscle, which can adversely affect clinical outcomes. Treatment with a peroxisome proliferating activating receptor-alpha drug may be a potential new therapeutic option.
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Affiliation(s)
- Melanie G Cree
- University of Arkansas Medical Sciences, Donald W. Reynolds Center on Aging, Nutrition, Metabolism and Exercise Lab, Little Rock, AR, USA
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Washington L, Cook GA, Mansbach CM. Inhibition of carnitine palmitoyltransferase in the rat small intestine reduces export of triacylglycerol into the lymph. J Lipid Res 2003; 44:1395-403. [PMID: 12700347 DOI: 10.1194/jlr.m300123-jlr200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Following digestion of dietary triacylglycerol (TAG), intestinal epithelial cells absorb fatty acids and monoacylglycerols that are resynthesized into TAG by enzymes located on the endoplasmic reticulum (ER). A study in rat liver (Abo-Hashema, K. A., M. H. Cake, G. W. Power, and D. J. Clarke. 1999. Evidence for TAG synthesis in the lumen of microsomes via a lipolysis-esterification pathway involving carnitine acyltransferases. J. Biol. Chem. 274: 35577-35582) showed that there is a carnitine-dependent ER lumenal synthesis of TAG. We wanted to test the hypothesis that a similar pathway was present in rat intestine by utilizing etomoxir, a specific inhibitor of carnitine palmitoyltransferase (CPT). Intraduodenal infusion of etomoxir inhibited CPT activity in the ER by 69%. Etomoxir did not affect either the uptake of intraduodenally infused [3H]glyceryltrioleate by the intestinal mucosa or the production of mucosal [3H]TAG, excluding the possibility that etomoxir interfered with TAG absorption or synthesis. Etomoxir did not inhibit protein synthesis, glucose, cholesterol or palmitate absorption or metabolism, or ATP concentrations. Etomoxir substantially (74%) diminished lymph TAG output from intralumenally infused glyceryltrioleate. In conclusion, these data strongly support the hypothesis that an ER CPT system exists and is necessary for processing dietary TAG into chylomicrons. The significant reduction in lymphatic output of chylomicron TAG on etomoxir treatment suggests that the major source of chylomicron TAG is a diacylglyceroltransferase on the lumenal surface of the ER.
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Affiliation(s)
- LaTonya Washington
- Department of Pharmacology, Department of Medicine, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38104, USA
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Ramsay RR, Gandour RD, van der Leij FR. Molecular enzymology of carnitine transfer and transport. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1546:21-43. [PMID: 11257506 DOI: 10.1016/s0167-4838(01)00147-9] [Citation(s) in RCA: 255] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Carnitine (L-3-hydroxy-4-N-trimethylaminobutyric acid) forms esters with a wide range of acyl groups and functions to transport and excrete these groups. It is found in most cells at millimolar levels after uptake via the sodium-dependent carrier, OCTN2. The acylation state of the mobile carnitine pool is linked to that of the limited and compartmentalised coenzyme A pools by the action of the family of carnitine acyltransferases and the mitochondrial membrane transporter, CACT. The genes and sequences of the carriers and the acyltransferases are reviewed along with mutations that affect activity. After summarising the accepted enzymatic background, recent molecular studies on the carnitine acyltransferases are described to provide a picture of the role and function of these freely reversible enzymes. The kinetic and chemical mechanisms are also discussed in relation to the different inhibitors under study for their potential to control diseases of lipid metabolism.
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Affiliation(s)
- R R Ramsay
- Centre for Biomolecular Sciences, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
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Broadway NM, Gooding JM, Saggerson ED. Carnitine acyltransferases and associated transport processes in the endoplasmic reticulum. Missing links in the VLDL story? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 466:59-67. [PMID: 10709628 DOI: 10.1007/0-306-46818-2_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- N M Broadway
- Department of Biochemistry and Molecular Biology, University College London, Great Britain
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Morillas M, Clotet J, Rubí B, Serra D, Asins G, Ariño J, Hegardt FG. Identification of the two histidine residues responsible for the inhibition by malonyl-CoA in peroxisomal carnitine octanoyltransferase from rat liver. FEBS Lett 2000; 466:183-6. [PMID: 10648838 DOI: 10.1016/s0014-5793(99)01788-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Carnitine octanoyltransferase (COT), an enzyme that facilitates the transport of medium chain fatty acids through peroxisomal membranes, is inhibited by malonyl-CoA. cDNAs encoding full-length wild-type COT and one double mutant variant from rat peroxisomal COT were expressed in Saccharomyces cerevisiae. Both expressed forms were expressed similarly in quantitative terms and exhibited full enzyme activity. The wild-type-expressed COT was inhibited by malonyl-CoA like the liver enzyme. The activity of the enzyme encoded by the double mutant H131A/H340A was completely insensitive to malonyl-CoA in the range assayed (2-200 microM). These results indicate that the two histidine residues, H131 and H340, are the sites responsible for inhibition by malonyl-CoA. Another mutant variant, H327A, abolishes the enzyme activity, from which it is concluded that it plays an important role in catalysis.
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Affiliation(s)
- M Morillas
- Department of Biochemistry and Molecular Biology, University of Barcelona, School of Pharmacy, Diagonal 643, 08028, Barcelona, Spain
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Zammit VA. Carnitine acyltransferases: functional significance of subcellular distribution and membrane topology. Prog Lipid Res 1999; 38:199-224. [PMID: 10664793 DOI: 10.1016/s0163-7827(99)00002-8] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- V A Zammit
- Hannah Research Institute, Ayr, Scotland, UK
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Asaka N, Muranaka Y, Kirimoto T, Miyake H. Cardioprotective profile of MET-88, an inhibitor of carnitine synthesis, and insulin during hypoxia in isolated perfused rat hearts. Fundam Clin Pharmacol 1998; 12:158-63. [PMID: 9565769 DOI: 10.1111/j.1472-8206.1998.tb00936.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
3-(2,2,2-trimethylhydrazinium) propionate (MET-88) is an inhibitor of carnitine synthesis. This study was carried out to investigate whether or not reduction of carnitine content could attenuate hypoxic damage in isolated perfused rat hearts. Rats were divided into four groups: 1) vehicle control; 2) pretreatment with MET-88 (MET-88); 3) application of insulin (500 muU/mL) in the perfusate (insulin); and 4) pretreatment with MET-88 and application of insulin (MET-88 + insulin). MET-88 (100 mg/kg) was orally administered once a day for 10 days until the day before the experiments. Hearts were initially perfused for a 10 min period under normoxia, followed by a 30 min period under hypoxia. Hearts were frozen at the end of hypoxia for the measurement of high-energy phosphates, carnitine derivatives, and glycolysis intermediates. In a separate series of untreated and MET-88 treated hearts, exogenous glucose and palmitate oxidation was measured. MET-88 decreased the extent of the depression of cardiac contractility (+dP/dt), and aortic flow during the hypoxic state. Insulin also improved cardiac function, and co-treatment of MET-88 and insulin additionally improved cardiac function during hypoxia. MET-88 prevented the decrease of high-energy phosphate and the increase of long-chain acylcarnitine after 30 min of hypoxic perfusion. In addition, MET-88 increased the steady state of glucose oxidation in hypoxic perfused rat hearts. These results indicate that MET-88 has cardioprotective effects on contractile function and energy metabolism of isolated perfused rat hearts in a hypoxic condition. Preventing the accumulation of long-chain acylcarnitine may serve to protect hypoxic hearts.
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Affiliation(s)
- N Asaka
- Pharmacology Research Laboratory, Taiho Pharmaceutical Co Ltd, Tokushima, Japan
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Power GW, Calder PC, Newsholme EA. The influence of dietary fatty acids on the activity and metabolic control of peroxisomal carnitine palmitoyltransferase in the liver. Nutr Res 1997. [DOI: 10.1016/s0271-5317(97)00052-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Diep QN, Brørs O, Bøhmer T. Formation of pivaloylcarnitine in isolated rat heart cells. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1259:161-5. [PMID: 7488636 DOI: 10.1016/0005-2760(95)00151-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Pivaloyl-containing antibiotics and pivalic acid in man or rat have been reported to cause increased urinary carnitine loss secondary to pivaloylcarnitine generation. Pivaloylcarnitine concentration was especially high in heart after administration of pivalic acid or pivampicillin in vivo. Formation of pivaloylcarnitine was therefore studied in isolated rat heart cells in the presence of sodium pivalate. Formation of pivaloylcarnitine in rat heart cells increased with incubation time, after a lag time from 0 to 2 h and linearly up to 6 h. The formation increased with increasing concentration of sodium pivalate, followed Michaelis-Menten kinetics with an apparent Km = 348 +/- 10 microM and Vmax = 116 +/- 20 pmol.mg protein-1.h-1. Bromoacetylcarnitine inhibited the pivaloylcarnitine formation to Ki = 116 +/- 43 microM and Vmax = 107 +/- 14 pmol.mg protein-1.h-1. The uptake of carnitine in heart cells was suppressed 62-74% by deoxycarnitine (40 microM) and D-carnitine (200 microM), and 95% by NaF (5 mM), NaN3 (500 microM) or at temperature 4 degrees C. Pivaloylcarnitine inhibited carnitine uptake to 33-35% of the controls, while sodium pivalate did not. More than 90% of intracellular pivaloylcarnitine was released from the heart cells after 18 h of incubation in the absence of sodium pivalate and L-carnitine. These data show that pivalate is readily converted to pivaloylcarnitine in heart cells, in contrast to the limited conversion in hepatocytes.
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Affiliation(s)
- Q N Diep
- Medical Department, Aker University Hospital, Oslo, Norway
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Choi SJ, Oh DH, Song CS, Roy AK, Chatterjee B. Molecular cloning and sequence analysis of the rat liver carnitine octanoyltransferase cDNA, its natural gene and the gene promoter. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1264:215-22. [PMID: 7495866 DOI: 10.1016/0167-4781(95)00146-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The full-length cDNA and the natural gene for rat peroxisomal carnitine octanoyltransferase (COT) have been isolated and sequenced. The 2681 bp long cDNA contains an open reading frame for 613 amino acids, resulting in a protein with a deduced molecular weight of 70,301, and a C-terminal peroxisomal targeting sequence (Ala-His-Leu). The isolated COT cDNA has 51 bp of the 5' untranslated region (UTR), 791 bp of 3' UTR, two putative polyadenylation sites, and a poly(A19-23) tail. Screening of a rat genomic DNA library in the lambda phage with the COT cDNA probe resulted in the isolation of seven overlapping clones, together containing the complete COT gene with seventeen exons. All of the exon-intron boundary sequences conform to the GT-AG rule. The COT gene appears to spread over 40 to 60 kbp region of the rat genome. The transcription initiation site of the COT gene was determined through primer extension, and the promoter sequence up to the position -1140 was established. The promoter lacks the canonical TATA box and a promoter-reporter construct containing the sequence encompassing -1140 to +84 base positions and the firefly luciferase reporter cDNA yielded about 100-fold increase in promoter activity in transfected hepatoma cells. Some of the consensus sequences for putative cis elements present in the promoter sequence are: the two CCAAT motifs for CTF/NF1/CBP binding (at -284 and -93), two GC boxes for Sp1 binding (at -160 and -68), two AP2 sites (at -359 and -25), a half site (TGACCT) for the peroxisome proliferator activated receptor (PPAR) binding at -737 within a partial palindromic sequence region. Potential regulatory elements, such as several palindromes and repeat motifs for five different sequence segments, are also identified.
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Affiliation(s)
- S J Choi
- Bioproducts Research Center, Yonsei University, Seoul, South Korea
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Niot I, Gresti J, Boichot J, Semporé G, Durand G, Bézard J, Clouet P. Effect of dietary n-3 and n-6 polyunsaturated fatty acids on lipid-metabolizing enzymes in obese rat liver. Lipids 1994; 29:481-9. [PMID: 7968269 DOI: 10.1007/bf02578245] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study was designed to examine whether n-3 and n-6 polyunsaturated fatty acids at a very low dietary level (about 0.2%) would alter liver activities in respect to fatty acid oxidation. Obese Zucker rats were used because of their low level of fatty acid oxidation, which would make increases easier to detect. Zucker rats were fed diets containing different oil mixtures (5%, w/w) with the same ratio of n-6/n-3 fatty acids supplied either as fish oil or arachidonic acid concentrate. Decreased hepatic triacylglycerol levels were observed only with the diet containing fish oil. In mitochondrial outer membranes, which support carnitine palmitoyltransferase I activity, cholesterol content was similar for all diets, while the percentage of 22:6n-3 and 20:4n-6 in phospholipids was enhanced about by 6 and 3% with the diets containing fish oil and arachidonic acid, respectively. With the fish oil diet, the only difference found in activities related to fatty acid oxidation was the lower sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition. With the diet containing arachidonic acid, peroxisomal fatty acid oxidation and carnitine palmitoyltransferase I activity were markedly depressed. Compared with the control diet, the diets enriched in fish oil and in arachidonic acid gave rise to a higher specific activity of aryl-ester hydrolase in microsomal fractions. We suggest that slight changes in composition of n-3 or n-6 polyunsaturated fatty acids in mitochondrial outer membranes may alter carnitine palmitoyltransferase I activity.
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Affiliation(s)
- I Niot
- Laboratoire de Nutrition Cellulaire et Métabolique, Université de Bourgogne, Faculté des Sciences Mirande, Dijon, France
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Kerner J, Zaluzec E, Gage D, Bieber L. Characterization of the malonyl-CoA-sensitive carnitine palmitoyltransferase (CPTo) of a rat heart mitochondrial particle. Evidence that the catalytic unit is CPTi. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37181-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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