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  • 1
    Electronic Resource
    Electronic Resource
    Reactivity of human leukocyte elastase and porcine pancreatic elastase toward peptide-4-nitroanilides containing model desmosine residues. Evidence that human leukocyte elastase is selective for crosslinked regions of elastin (1981)
    s.l. : American Chemical Society
    Biochemistry 20 (1981), S. 3675-3679 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00516a002
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  • 2
    Electronic Resource
    Electronic Resource
    Interaction of methylmercury compounds with albumin (1990)
    Springer
    Archives of toxicology 64 (1990), S. 639-643 
    Details
    ISSN: 1432-0738
    Keywords: Methylmercury ; Bovine serum albumin ; Mercaptide ; Glutathione ; Mixed disulfide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The nature of interaction between bovine serum albumin (BSA) and methylmercurial compounds has been investigated by ultrafiltration analysis. Four types of BSA samples, mercaptalbumin, its mixed disulfides with glutathione (GSH) andl-cysteine (CySH), and the S-carbami-domethylated derivative, were used for binding assays with methylmercury (MM) chloride (MMC) and three kinds of MM mercaptides of low molecular weight thiols, GSH (GS-MM), CySH (CyS-MM) and cysteinylglycine (CG-MM). Among various ligands tested, MMC showed the highest affinity for all BSA species, and the BSA-bound fraction of the ligand did not change with ligand/protein ratio. MMC strongly and stoichiometrically bound to mercaptalbumin even at a molar ratio of 1∶1. In contrast, the albumin bound fractions of three other MM ligands increased with concomitant decrease in ligand/protein ratio and with time except for the alkylated albumin, the highest binding being shown by mercaptalbumin. Binding of S-2-nitrophenyl-glutathione, a GSH analog with a hydrophobic S-substituent, to albumin species occurred similarly to that of GS-MM. However, GSH and oxidized glutathione (GSSG) interacted differently with albumin; mercaptalbumin showed the lowest affinity for GSH, and GSSG scarcely interacted with all BSA species. These results suggest that the sulfhydryl group at Cys-34 is not the only site of BSA that interacts with MM compounds and that albumin interacts preferentially with the hydrophobic domains of a mercurial ligand rather than its hydrophilic peptide moiety.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974691
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  • 3
    Electronic Resource
    Electronic Resource
    Acute effects of methylmercury on hepatic and renal glutathione metabolisms in mice (1994)
    Springer
    Archives of toxicology 68 (1994), S. 512-516 
    Details
    ISSN: 1432-0738
    Keywords: Key words: Mouse – Methylmercury – Glutathione –γ-Glutamylcysteine synthetase – Renal failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Because of its high affinity to the sulfhydryl group, the in vivo fate of methylmercury (MeHg) is closely related to the glutathione (GSH) metabolism. Here, to examine the possible effects of MeHg on the GSH metabolism, C57BL female mice were challenged by this heavy metal at a marginal dose level to induce slight renal dysfunction. Liver and blood GSH levels decreased by 16% and 20%, respectively, 24 h after MeHg (160 μmol/kg) administration, whereas kidney and plasma levels drastically increased. The GSH half-lives obtained using L-buthionine-(S,R)-sulfoximine were shortened by 17% in the liver, but lengthened by 28% in the kidney. The accelerated secretion of GSH from the liver and/or blood cells might have caused increased plasma levels of the tripeptide, which in turn could increase the supply of the constituent amino acids for GSH synthesis to the kidney. Furthermore, renal γ-glutamylcysteine synthetase activity, a rate-determining enzyme in GSH biosynthesis, was found to be enhanced in the MeHg-treated group. The marked increase in the renal GSH levels induced by MeHg could be due to the increased synthesis and the decreased efflux of the tripeptide in this tissue. The MeHg-induced alterations of GSH metabolism described here might reflect one of the defense mechanisms of bioorganisms against the challenge by MeHg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050104
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  • 4
    Electronic Resource
    Electronic Resource
    Induction by mercury compounds of brain metallothionein in rats: Hg0 exposure induces long-lived brain metallothionein (1998)
    Springer
    Archives of toxicology 72 (1998), S. 187-191 
    Details
    ISSN: 1432-0738
    Keywords: Key words Methylmercury ; Mercury vapor ; Metallothionein ; Brain ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Metallothionein (MT) is one of the stress proteins which can easily be induced by various kind of heavy metals. However, MT in the brain is difficult to induce because of blood-brain barrier impermeability to␣most heavy metals. In this paper, we have attempted to induce brain MT in rats by exposure to methylmercury (MeHg) or metallic mercury vapor, both of which are known to penetrate the blood-brain barrier and cause neurological damage. Rats treated with MeHg (40 μmol/kg per day × 5 days, p.o.) showed brain Hg levels as high as 18 μg/g with slight neurological signs 10␣days after final administration, but brain MT levels remained unchanged. However, rats exposed to Hg vapor for 7 days showed 7–8 μg Hg/g brain tissue 24 h after cessation of exposure. At that time brain MT levels were about twice the control levels. Although brain Hg levels fell gradually with a half-life of 26 days, MT levels induced by Hg exposure remained unchanged for 〉2␣weeks. Gel fractionation revealed that most Hg was in the brain cytosol fraction and thus bound to MT. Hybridization analysis showed that, despite a significant increase in MT-I and -II mRNA in brain, MT-III mRNA was less affected. Although significant Hg accumulation and MT induction were observed also in kidney and liver of Hg vapor-exposed rats, these decreased more quickly than in brain. The long-lived MT in brain might at least partly be accounted for by longer half-life of Hg accumulated there. The present results showed that exposure to Hg vapor might be a suitable procedure to provide an in vivo model with enhanced brain MT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050486
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  • 5
    Electronic Resource
    Electronic Resource
    Strain difference in mercury excretion in methylmercury-treated mice (1986)
    Springer
    Archives of toxicology 59 (1986), S. 99-102 
    Details
    ISSN: 1432-0738
    Keywords: Methylmercury ; Excretion ; Distribution ; Strain difference ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The strain differences in mercury excretion and organ distribution after administration of methylmercuric chloride (5 mg/kg) were studied in male mice of four strains, C57BL/6N, BALB/cA, C3H/HeN and AKR. The urinary excretion rate of mercury for 5 days following administration was 3.9–4.7 times higher in the C57BL strain than in the other three strains, whereas the mercury level in feces was highest in the AKR strain. Although the blood mercury concentration in the C57BL strain was almost half that in the others up to the 5th day, the plasma levels did not vary so widely. C57BL showed the highest ratio of plasma to whole blood mercury level, which was thought to originate from the lower affinity of methylmercury for hemoglobin. The variation of the plasma/whole blood ratios was rather small throughout the experimental period in each strain examined. In the C57BL strain, the mercury levels in brain, liver, kidney and blood were significantly lower on and after the 5th day than in the other three strains, probably because of the rapid elimination of body mercury into urine, but the mercury uptake by the brain and kidney 5 min after administration was at a rather higher rate than in the other strains. On the other hand, the highest tissue levels were shown by the C3H strain in the brain and liver, and by the BALB/c strain in the kidney. It was suggested that in the C57BL strain, the higher mercury distribution in plasma and rapid uptake by the kidney might result in higher urinary excretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00286731
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanism of urinary excretion of methylmercury in mice (1989)
    Springer
    Archives of toxicology 63 (1989), S. 479-483 
    Details
    ISSN: 1432-0738
    Keywords: Mercury metabolism ; Glutathione ; Detoxication ; Renal transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To elucidate the mechanism by which methylmercury (MeHg) is eliminated from organisms, male C57BL/6N mice were orally administered with MeHg chloride (5 mg/kg) and the chemical forms of its metabolites in plasma, urine and the kidney were determined by column chromatographic analysis. Orally administered MeHg rapidly entered the circulation, accumulated in the kidney and other tissues, and was slowly excreted in the urine. Ultrafiltration and gel filtration analysis revealed that most of plasma MeHg was accounted for by its albumin conjugate. Cell fractionation analysis revealed that about 80% of renal MeHg was recovered from the 15 000 g supernatant fraction of the kidney homogenate. If the kidney was homogenized in the presence of serine-borate complex, a potent inhibitor of γ-glutamyltranspeptidase (γ-GTP), about 50% of the MeHg in the supernatant fraction was recovered as its glutathione S-conjugate while the rest was bound to cytosolic protein(s). The major part of urinary MeHg was accounted for by its cysteine conjugate. However, urinary excretion of its glutathione conjugate increased significantly if animals were pretreated with acivicin, an affinity labeling reagent for γ-GTP. These and other results suggested that MeHg bound to albumin accumulated in the kidney predominantly via some non-filtrating peritubular mechanism, and localized in renal cytosolic compartment as its glutathione- and protein-bound forms. The glutathione S-conjugate of MeHg in the tubule cells might be transferred to the lumenal space, hydrolyzed to the cysteine S-conjugate, and then excreted in urine. These sequential events might constitute an important eliminatory pathway for a hazardous mercurial metabolite in mice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316452
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  • 7
    Electronic Resource
    Electronic Resource
    Selective quantification of inorganic mercury in tissues of methylmercury-treated rats (1990)
    Springer
    Bulletin of environmental contamination and toxicology 45 (1990), S. 662-666 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01700983
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