Degradation of hepatic zinc-thionein after parenteral zinc administration.
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ABSTRACT:
SUBMITTER: Feldman SL
PROVIDER: S-EPMC1164273 | biostudies-other | 1976 Dec
REPOSITORIES: biostudies-other
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Project description:The rate of [35S]cystine incorporation into hepatic zinc-thionein (a metallothionein) was stimulated, with a maximum of 5-6h, after parenteral administration of 2mg of Zn2+ containing 65Zn. The binding of 65Zn to zinc-thionein was measurable by 2-1/2h and reached a plateau by 18h after the injection. A net increase in the hepatic 65Zn content was observed subsequent to the decrease in the rate of zinc-thionein synthesis. The incorporation of both 65Zn and [35S]cystine into zinc-thionein was inhibited by prior administration of either actinomycin D or cordycepin. A second injection of Zn2+, 20h after the initial injection, yielded a 4.9-fold greater increase in zinc-thionein synthesis compared with that after only one injection; however, this synthesis was also inhibitable by actinomycin D. These data support the concept that hepatic zinc-thionein synthesis responds quickly to changes in Zn2+ status and that Zn2+ is bound subsequent to synthesis of nascent thionein chains. The mechanism of control of zinc-thionein synthesis by Zn2+ appears to involve changes in the amounts of a short-lived, poly(A)-containing RNA whose translation can be derepressed by additional exposure to Zn2+.
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Project description:AimThe aim of the present study is to investigate the effect of long-term zinc supplementation, which is important for the activation of various enzymes that contribute to antioxidant and antifibrotic activities, on the improvement of serum fibrotic markers in patients with autoimmune hepatitis (AIH).MethodsA total of 38 patients with AIH under regular treatment at our hospital who provided their consent for being treated with polaprezinc (75 mg twice daily) were included and classified into 2 groups: the patients with zinc elevation (n = 27) and the patients without zinc elevation (n = 11). Serum biomarker of fibrosis, protein expression levels of matrix metalloproteinases (MMPs), and their inhibitors (TIMPs) were evaluated.ResultsA significant difference was found between the variability of serum procollagen type Ⅲ and collagen type Ⅳ-7S between the 2 groups before and after zinc administration for more than 24 months (p = 0.043 and p = 0.049). In the patients with zinc elevation, no significant changes were found in collagenase (MMP-1 and MMP-13) before and after zinc administration, whereas a significant increase in the expression of gelatinase (MMP-2 and MMP-9) was found after administration (p = 0.021 and p = 0.005). As for the relative ratio of MMPs to TIMPs, only MMP-9 to TIMP-1 showed a significant increase (p = 0.004).ConclusionsLong-term treatment with polaprezinc has been demonstrated to safely improve serum fibrosis indices through increases in MMP-2/-9 and MMP-9/TIMP-1 and is expected to be well combined with direct antifibrotic therapies such as molecularly targeted agents.
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Project description:The ability of rat liver zinc-thionein to donate its metal to the apo-enzymes of the zinc enzymes horse liver alcohol dehydrogenase, yeast aldolase, thermolysin, Escherichia coli alkaline phosphatase and bovine erythrocyte carbonic anhydrase was investigated. Zinc-thionein was as good as, or better than, ZnSO(4), Zn(CH(3)CO(2))(2) or Zn(NO(3))(2) in donating its zinc to these apo-enzymes. Apo-(alcohol dehydrogenase) could not be reactivated by zinc salts or by zinc-thionein. Incubation of the other apo-enzymes with near-saturating amounts of zinc as ZnSO(4), Zn(CH(3)CO(2))(2), Zn(NO(3))(2), or zinc-thionein resulted in reactivation of the apo-enzymes. With apo-aldolase zinc-thionein gave 100% reactivation within 30min. Reactivation by ZnSO(4) and Zn(CH(3)CO(2))(2) was complete and instantaneous. Zinc-thionein was somewhat better than Zn(NO(3))(2) in completely reactivating apo-thermolysin. With apo-(alkaline phosphatase) 43% reactivation was obtained with Zn(CH(3)CO(2))(2) and 18% with zinc-thionein. With apo-(carbonic anhydrase) zinc-thionein was better than ZnSO(4), Zn(CH(3)CO(2))(2) or Zn(NO(3))(2), with a maximal reactivation of 54%. That zinc was really being transferred from zinc-thionein to apo-(carbonic anhydrase) was shown by the fact that 2,6-pyridine dicarboxylic acid and 1,10-phenanthroline had minimal effects on the reactivation of apo-(carbonic anhydrase) when added after the incubation {[apo-(carbonic anhydrase)+zinc thionein]+chelator}, but inhibited reactivation when added before the incubation {apo-(carbonic anhydrase)+[zinc-thionein+chelator]}. These observations support the idea that zinc-thionein can function in zinc homeostasis as a reservoir of zinc, releasing the metal to zinc-requiring metalloenzymes according to need.
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Project description:Metal-dependent changes in the properties of metallothionein were investigated in vitro by replacing Zn2+ in zinc-thionein with Cu+ and Cu2+. Metallothionein was separated into isoproteins on a gel-permeation column by elution with alkaline buffer solution, the separation being due to the dissociation of hydroxy groups in the gel material. The two metals in metallothioneins were detected simultaneously by introducing the eluate of the column, which was attached to a high-pressure liquid chromatograph, to two flame atomic-absorption spectrophotometers. Zn2+ in zinc-thionein was replaced with 1.5 and 1 mol. equiv. of Cu+ and Cu2+ respectively. The replacement with Cu2+ accompanied intramolecular oxidation of thiol groups in metallothioneins and the oxidized metallothioneins showed different chromatographic properties from the original ones, probably due to changes in the isoelectric points. The oxidized forms of metallothionein were reducible by mercaptoethanol. Reduction of Cu2+ to Cu+ followed by the replacement of Zn2+ in zinc-thionein with Cu+ occurred in the presence of glutathione.
| S-EPMC1163371 | biostudies-other
Project description:To improve the safety and efficacy of oral rotavirus vaccines, we developed an inactivated rotavirus vaccine (IRV) for parenteral administration. Since it remains unknown whether parenteral vaccination can induce mucosal immunity, we performed a comprehensive assessment of immune responses to IRV in mice with an adjuvant-free dissolving polymer MN patch or by alum-adjuvanted IM injection. We demonstrated that IRV induced the expression of the gut homing receptor LPAM-1 on T and B cells in spleen and mLN of vaccinated mice. MN patch IRV vaccination induced a slight Th1 phenotype while IM vaccination induced a balanced Th1/Th2 phenotype. In addition, a dose-sparing effect was seen for rotavirus-specific serum IgG and neutralizing activity for both vaccination routes. Our study is the first to show that parenterally administered IRV can induce mucosal immunity in the gut, in addition to strong serum antibody response, and is a promising candidate vaccine in achieving global immunization against rotavirus.
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Project description:Alcoholic liver disease is associated with sustained liver damage and impaired regeneration, as well as significant zinc deficiency. This study was undertaken to examine whether dietary zinc supplementation could improve liver regeneration by increasing the expression of genes involved in hepatic cellular proliferation in a mouse model of alcoholic liver disease. Adult 129S6 mice fed an ethanol-containing liquid diet for 6 months developed alcoholic liver disease as measured by serum alanine transferase activity and histopathological changes. Zinc supplementation to ethanol-exposed mice enhanced liver regeneration as indicated by increased numbers of proliferation cell nuclear antigen (PCNA)-positive and bromodeoxyuridine (BrdU)-labeled hepatocytes. Zinc-enhanced liver regeneration was associated with an increase in hepatocyte nuclear factor-4alpha (HNF-4alpha), a liver-enriched, zinc-finger transcription factor. Studies using cultured HepG2 cells showed that zinc deficiency suppressed cell proliferation and cell proliferation-related proteins, including hepatocyte growth factor (HGF), insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 1 (IGFBP1), metallothionein (MT), and cyclin D1, as well as HNF-4alpha. HNF-4alpha gene silencing inhibited cell proliferation in association with decreased protein levels of IGF-I, IGFBP1, MT, and cyclin D1. The present study provides evidence that zinc supplementation enhances liver regeneration at least in part by HNF-4alpha through the up-regulation of cell proliferation-related proteins, suggesting that dietary zinc supplementation may have beneficial effects in alcoholic liver disease.
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Project description:Intestinal failure-associated liver disease (IFALD) is a risk of parenteral nutrition (PN)-dependence. Intravenous soybean oil-based parenteral fat can exacerbate the risk of IFALD while intravenous fish oil can minimize its progression, yet the mechanisms by which soybean oil harms and fish oil protects the liver are uncertain. Properties that differentiate soybean and fish oils include α-tocopherol and phytosterol content. Soybean oil is rich in phytosterols and contains little α-tocopherol. Fish oil contains abundant α-tocopherol and little phytosterols. This study tested whether α-tocopherol confers hepatoprotective properties while phytosterols confer hepatotoxicity to intravenous fat emulsions. Utilizing emulsions formulated in the laboratory, a soybean oil emulsion (SO) failed to protect from hepatosteatosis in mice administered a PN solution enterally. An emulsion of soybean oil containing α-tocopherol (SO+AT) preserved normal hepatic architecture. A fish oil emulsion (FO) and an emulsion of fish oil containing phytosterols (FO+P) protected from steatosis in this model. Expression of hepatic acetyl CoA carboxylase (ACC) and peroxisome proliferator-activated receptor gamma (PPARγ), was increased in animals administered SO. ACC and PPARγ levels were comparable to chow-fed controls in animals receiving SO+AT, FO, and FO+P. This study suggests a hepatoprotective role for α-tocopherol in liver injury induced by the enteral administration of a parenteral nutrition solution. Phytosterols do not appear to compromise the hepatoprotective effects of fish oil.
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Project description:BackgroundIntravenous (IV) hydration is considered a protective factor in reducing the incidence of acyclovir-induced nephrotoxicity. A systems-based review of cases of acyclovir-associated acute kidney injury can be used to examine institution-, care provider-, and task-related factors involved in administering the drug and can serve as a basis for developing a quality improvement intervention to achieve safer administration of acyclovir.ObjectivesTo explore the effectiveness of the study institution's inter-disciplinary quality improvement intervention in increasing the dilution of acyclovir before IV administration.MethodsAfter conducting a systems-based review for intervention development, a retrospective analysis was undertaken to compare IV administration of acyclovir in the 6-month periods before and after implementation of the intervention. The study population was a sequential sample of all patients over 18 years of age who were seen in the emergency department or admitted to a ward and who received at least one IV dose of acyclovir at the study institution. The primary outcome was the volume in which each acyclovir dose was delivered. The secondary outcomes were the hourly rate of fluid administration, the frequency of an increase in hourly hydration rate, and the incidence of acute kidney injury.ResultsEighty-four patients (44 in the pre-intervention period and 40 in the post-intervention period) received IV acyclovir and had evaluable data for the primary outcome. The median volume in which the acyclovir dose was administered was significantly higher in the post-intervention group (250 mL versus 100 mL, p < 0.001).ConclusionsIn this study, an easily implemented intervention significantly increased the volume of IV fluid administered to patients receiving acyclovir. Adequately powered prospective studies are suggested to investigate the effectiveness of this intervention on the clinically relevant incidence of acyclovir-induced nephrotoxicity.
| S-EPMC4777587 | biostudies-literature
Project description:Prematurity and overfeeding in infants are associated with insulin resistance in childhood and may increase the risk of adult disease. Total parenteral nutrition (TPN) is a major source of infant nutritional support and may influence neonatal metabolic function. Our aim was to test the hypothesis that TPN induces increased adiposity and insulin resistance compared with enteral nutrition (EN) in neonatal pigs. Neonatal pigs were either fed enteral formula orally or i.v. administered a TPN mixture for 17 d; macronutrient intake was similar in both groups. During the 17-d period, we measured body composition by dual-energy X-ray absorptiometry scanning; fasting i.v. glucose tolerance tests (IVGTT) and hyperinsulinemic-euglycemic clamps (CLAMP) were performed to quantify insulin resistance. On d 17, tissue was collected after 1-h, low-dose CLAMP for tissue insulin signaling assays. TPN pigs gained less lean and more body fat and developed hepatic steatosis compared with EN pigs. After 7 and 13 d, IVGTT showed evidence of insulin resistance in the TPN compared with the EN group. Fasting plasma glucose and insulin also were higher in TPN pigs. CLAMP showed that insulin sensitivity was markedly lower in TPN pigs than in EN pigs. TPN also reduced the abundance of the insulin receptor, insulin receptor substrate 1, and phosphatidylinositol 3 kinase in skeletal muscle and liver and the proliferation of total pancreatic cells and ?-cells. Hepatic proinflammatory genes as well as c-Jun-N-terminal kinase 1 phosphorylation, plasma interleukin 6, and tumor necrosis factor-? were all higher in TPN pigs than in EN pigs. The results demonstrate that chronic TPN induces a hepatic inflammatory response that is associated with significant insulin resistance, hepatic steatosis, and fat deposition compared with EN in neonatal pigs. Further studies are warranted to establish the mechanism of TPN-induced insulin resistance and hepatic metabolic dysfunction and whether there are persistent metabolic consequences of this lifesaving form of infant nutritional support.
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