metallothionein and Burns

The requirement of zinc for humans was recognized in the early 1960s. The causes of zinc deficiency include malnutrition, alcoholism, malabsorption, extensive burns, chronic debilitating disorders, and chronic renal diseases; use of certain drugs such as penicillamine and, in some cases, diuretics; and genetic disorders such as acrodermatitis enteropathica and sickle cell disease. The requirement of zinc is increased in pregnancy and during growth. The clinical manifestations of severe zinc deficiency include bullous-pustular dermatitis, alopecia, diarrhea, emotional disorder, weight loss, intercurrent infections, and hypogonadism in males; zinc deficiency can be fatal if unrecognized and untreated. A moderate deficiency of zinc is characterized by growth retardation and delayed puberty in adolescents, hypogonadism in males, rough skin, poor appetite, mental lethargy, delayed wound healing, taste abnormalities, and abnormal dark adaptation. In mild cases of zinc deficiency in human subjects, we have observed oligospermia, slight weight loss, and hyperammonemia. Zinc is a growth factor. As a result of its deficiency, growth is affected adversely in many animal species and humans, probably because zinc is needed for protein and DNA synthesis and cell division. The effects of zinc and growth hormone on growth appear to be independent of each other in experimental animals. Whether zinc is required for the metabolism of somatomedin needs further investigation. Thyroid and adrenal functions do not appear to change as a result of zinc deficiency. Glucocorticoids may have an effect on zinc metabolism, although the clinical relevance of this effect is not known at present. In contrast, testicular function is affected adversely as a result of zinc deficiency in both humans and experimental animals. The effect appears to be a direct one since the hypothalamic-pituitary axis is intact, and may relate to the reduction in testicular size as a result of the need for zinc in cell division. In addition, zinc is required for the function of several testicular enzymes, although a specific role in steroidogenesis has not been identified. Zinc appears to have a role in the modulation of prolactin secretion, in the secretion and action of insulin, and in the production and biologic effects of thymic hormones. It is clear that the endocrine consequences of zinc deficiency are multiple, and that continued investigation should provide additional pathophysiologic and therapeutic i

Topics: Burns; Cell Membrane; Chronic Disease; Endocrine Glands; Enzymes; Female; Gastrointestinal Diseases; Genetic Diseases, Inborn; Growth; Humans; Immunity; Kidney Diseases; Metallothionein; Nucleic Acids; Pregnancy; Skin Diseases; Zinc

Metallothioneins (MTs) are a family of low molecular-weight and cysteine-rich metalloproteins that regulate metal metabolism and protect cells from oxygen free radicals. Recent studies suggested that MTs have some anti-inflammatory effects. However, the role of MTs in post-burn inflammation remains unclear. This study is designed to investigate the role of MTs in post-burn inflammation in a mouse burn model. MT-I/II null (-/-) and C57BL/6 wild-type (WT) mice were randomly divided into sham burn, burn, Zn treated, and Zn-MT-2 treated groups. The inflammatory cytokines levels were measured by enzyme-linked immunosorbent assay (ELISA). Myeloperoxidase (MPO) activity was determined by spectrophotometry. In in vitro study, exogenous MT-2 was added to macrophages that were stimulated with burn serum in the presence or absence of a p38 MAPK inhibitor SB203580. The IL-6 and TNF-α messenger RNA (mRNA) expression were detected by quantitative real-time polymerase chain reaction. The levels of p38 expression were determined by Western blot. Burn induced increased inflammatory cytokines such as interleukin (IL)-1β, IL-6, tumor necrosis factors-α, and macrophage chemoattractant protein-1 production in burn wound and serum. The MPO activities in the lung and heart were also increased after burn. These effects were significantly more prominent in MT (-/-) mice than in WT mice. Furthermore, these effects were inhibited by administration of exogenous MT-2 to both WT and MT (-/-) mice. Exogenous MT-2 inhibited the p38 expression and abrogated the increase of IL-6 and TNF-α mRNA expression from macrophages that were stimulated with burn serum. The effect of MT-2 was not further strengthened in the presence of SB203580. MTs may have a protective role against post-burn inflammation and inflammatory organ damage, at least partly through inhibiting the p38 MAPK signaling.

Topics: Animals; Burns; Chemokine CCL2; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Imidazoles; Inflammation; Interleukin-1beta; Interleukin-6; Macrophages; Male; MAP Kinase Signaling System; Metallothionein; Mice; Mice, Inbred C57BL; Mice, Knockout; p38 Mitogen-Activated Protein Kinases; Peroxidase; Pyridines; Real-Time Polymerase Chain Reaction; RNA, Messenger; Tumor Necrosis Factor-alpha

Metallothionein (MT) is a small cysteine-rich protein that sequesters and distributes metal ions. Its overexpression stimulates cell proliferation and inhibits apoptosis. We investigated the effects of burn injury on MT expression and metal localization. We also sought to determine roles of MT in the pathophysiologic alterations in the liver after injury.. Mice (C57BLKS/J, MT-I/II knock-out, KO, and wild-type control mice) were subjected to an 18% burn. Liver tissues harvested after injury were analyzed for the MT expression and the levels of zinc, copper, manganese, and iron. Levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase were measured in serum samples from MT-I/MT-II KO mice and controls after injury.. Transient induction of MT-I and MT-II mRNAs was observed 3-6 h after injury, while MT-I/MT-II protein peaked on day 1. The induction was localized to hepatocytic nuclei. The intrahepatic levels of zinc, copper, and iron were transiently elevated on day 1, when a downregulation of manganese was evident. Interestingly, only the serum levels of aspartate aminotransferase were significantly augmented in MT-I/MT-II KO mice compared to controls after injury.. These data suggest that MT and metals may participate in the pathogenesis of the liver after burn injury.

Topics: Alanine Transaminase; Alkaline Phosphatase; Animals; Aspartate Aminotransferases; Blotting, Western; Burns; Disease Models, Animal; Enzymes; Gene Expression; Immunoenzyme Techniques; Liver; Metallothionein; Metals, Heavy; Mice; Mice, Inbred C57BL; Mice, Knockout; RNA, Messenger

Using the model of burned animal with delayed resuscitation to study antagonistic effect of Zn7-metallothionein (Zn7-MT) on oxidative stress in the liver of rats suffered from severe thermal injury on skin.. To compare the changes in antioxidant concentrations and antioxidative enzyme activities in the liver or plasma of burned rats with or without Zn7-MT in resuscitation fluid by biochemical assay.. After injury, glutathione concentration was progressively decreased with time. At 24 h after injury, activities of glutathione reductase and glutathione peroxidase in the liver of burned rats were increased and then decreased at 48 h postburn. Alpha-tocopherol in plasma was reduced at 24 h and malondialdehyde in the liver was increased significantly postburn. MT and MT-1 mRNA expression in burned rats were activated. Taken together, oxidative stress in the liver of burned rats occurred. Exogenous Zn7-MT attenuated the changes in antioxidant concentrations and antioxidative enzyme activities in the liver or plasma of burned rats. The effect of Zn7-MT was in a concentration-dependent manner and the concentration of 10 micromol/L was the most effective. Exogenous Zn7-MT also inhibited MT-1 mRNA overexpression and increased MT protein concentration.. Zn7-MT effectively antagonized oxidative stress in the liver of rats with severe thermal injury.

Topics: alpha-Tocopherol; Animals; Antioxidants; Burns; Glutathione; Glutathione Peroxidase; Glutathione Reductase; Liver; Male; Malondialdehyde; Metallothionein; Oxidative Stress; Random Allocation; Rats; Rats, Wistar; Zinc

To study the antagonism of Zn-metallothionein (Zn-MT) to oxidative stress of rats with severe scalding after delayed resuscitation.. 27 Wistar rats were randomly divided into three groups: normal control; burn with delayed fluid resuscitation group; and Zn-MT protected group. The rats were scalded with 30% total body surface area (TBSA) third degree burn. Four hours after injury, they were resuscitated, but Zn-MT (1 x 10(-5) mol/L) was given in the third group rats. 24 hours after they were scalded, blood was taken, RBCs were separated and labeled with electron spin resonance (ESR) spin label 3-maleimido-proxy l to detect membrane protein conformation. The serum was collected and added into the reaction system of xanthine, xanthine oxidase and ESR spin trap 5, 5-dimethylpyroline-N-oxide to assay the levels of superoxide dismutase (SOD) by ESR.. The ratios of strong solidity and weak solidity of RBC membrane proteins in the three groups were 0.352 +/- 0.043, 0.409 +/- 0.027, and 0.386 +/- 0.062 respectively, and the revolved times of membrane proteins were 1.300 +/- 0.210, 1.576 +/- 0.190 and 1.381 +/- 0.210 seconds respectively. Compared to the first group, the membrane protein conformation in the second group was changed remarkably, and the speed of membrane protein movement decreased significantly. However, those changes were alleviated obviously by Zn-MT. The SOD levels in serum of the three groups rats were 73.2% +/- 1.4%, 48.8% +/- 3.8% and 66.8% +/- 3.2% respectively. Compared to the normal control group, the SOD levels in serum of the second group decreased obviously. However, an excess of oxygen free radicals produced after injury could be scavenged by Zn-MT.. RBC membrane proteins of rats with severe scalding after delayed resuscitation were injured by oxygen free radicals produced after injury, and Zn-MT could alleviate this injury.

Topics: Animals; Burns; Disease Models, Animal; Erythrocyte Membrane; Female; Male; Metallothionein; Protective Agents; Rats; Rats, Wistar; Reactive Oxygen Species; Superoxide Dismutase; Zinc

The aim of this work was to study oxidative stress and the compensating mechanisms implicated in severe thermal injury using the burned rat model. Results showed that after thermal injury glutathione (GSH) level was decreased, oxidized glutathione (GSSG) and the ratio of GSSG/GSH increased both at 24 and 48 h in the liver. The activities of GSH-reductase (GSH-Rx) in the liver and GSH-peroxidase (GSH-Px) both in the liver and erythrocytes increased at 24 h and then decreased at 48 h. The level of alpha-tocopherol in plasma was reduced at 24 h. Lipid peroxide levels increased both at 24 and 48 h in the liver. The serum zinc level decreased, reaching a minimum at 12h, whereas liver zinc level was elevated and reached the maximum at 12 h. After severe thermal injury enhancement of metallothionein (MT) expression has been discovered for the first time. MT content in the liver increased both at 24 and 48 h. Expression of MT-I mRNA was activated at 3 h and reached the top at 24 h postburn. The conclusion is that severe thermal injury gives rise to oxidative stress and dramatic enhancement of MT expression could be one of the important compensative mechanisms of natural defense system postburn.

Topics: alpha-Tocopherol; Animals; Burns; Disease Models, Animal; Glutathione; Glutathione Reductase; Liver; Male; Metallothionein; Oxidative Stress; Rats; Rats, Wistar; Time Factors; Zinc

To investigate the protective effects of metallothionein (MT) on severely scalded rats inflicted by oxygen free radicals after delayed resuscitation.. Wistar rats inflicted by 30% TBSA III degree scalding injury were taken as the model. Fifty-Six rats were randomly divided into four groups, i.e. normal control, delayed resuscitation, MT treated and VitC treated groups. The changes in superoxide dismutase (SOD) and malondialdehyde (MDA) contents in plasma and subeschar edematous fluid were determined at 24 and 48 postburn hours with traditional indirect detecting method and electron spin resonance (ESR). Pathomorphological examination was simultaneously carried out for cardiac, hepatic, renal and intestinal samples. Plasma biochemical indices were determined at the same time.. In delayed resuscitation group, SOD content decreased and the MDA contents increased in plasma and subeschar fluid obviously, with remarkable changes in the pathomorphology of all the internal organs and the blood biochemical indices. But in MT treating group, SOD content increased (P < 0.05) with decreased content of MDA (P < 0.05) and the pathomorphology and blood biochemical indices improved significantly when compared with those in delayed resuscitation group and VitC treatment group.. MT treatment might be beneficial in the management of severely scalding rats infliced by oxygen free radicals.

Topics: Alanine Transaminase; Animals; Ascorbic Acid; Aspartate Aminotransferases; Blood Urea Nitrogen; Body Fluids; Burns; Creatine Kinase; Creatine Kinase, MB Form; Female; Hydroxybutyrate Dehydrogenase; Isoenzymes; L-Lactate Dehydrogenase; Male; Malondialdehyde; Metallothionein; Rats; Rats, Wistar; Reactive Oxygen Species; Superoxide Dismutase; Time Factors

To investigate the changes in liver metallothionein (MT) in scalded rats.. The scalded rats in deficient zinc condition were fed with diets containing zinc 4 micrograms/g, 10 micrograms/g, and 80 micrograms/g respectively. The changes in serum zinc, liver zinc and liver MT were observed.. The serum zinc decreased, liver zinc and MT increased. The higher diet zinc levels were, The higher serum zinc, liver zinc and MT became. The correlation analysis showed that the changes between liver zinc level and liver MT was positive relationship(r = 0.85, P < 0.01).. Serum zinc decrease, liver zinc increase after burn. This is connect with increment of MT synthesis in liver, zinc is inducer to MT. It can improve synthesis of liver MT.

Topics: Animals; Burns; Male; Metallothionein; Random Allocation; Rats; Rats, Sprague-Dawley; Zinc

To elucidate the relationship between skin viability and lipid peroxidation after deep partial thickness burn injury.. Deep partial thickness burn was produced. Metallothionin (MT) in different concentrations (0.5 x 10(-6) mol/L, 1 x 10(-5) mol/L) was topically applied. Oxygen consumption, succinate dehydrogenase(SDH), Schiff's base contents and healing time of wound were determined in 24 Wistar rats. Specimens were harvested at 8, 24, and 48-hour postburn.. Oxygen consumption and SDH value decreased and Schiff's base value increased after burn injury. With the application of MT, oxygen consumption and SDH value of burned skin were significantly higher compared with control group, and Schiff's base value was significantly lower (P < 0.05 or P < 0.01). The mean healing time of burned wound was two days less in two MT protection groups.. MT may be beneficial in improving postburn skin viability by attenuating lipid peroxidation of burned tissue.

Topics: Animals; Burns; Lipid Peroxidation; Male; Metallothionein; Oxygen Consumption; Rats; Rats, Wistar; Succinate Dehydrogenase; Wound Healing

The levels of reduced metallothioneins (MT) in peritoneal macrophages and liver of mice subjected to combined radiation and chemical injury displayed opposite changes: the macrophage level of MT decreased and the liver MT increased. Simultaneously, there was an increase in luminol- and lucigenin-dependent chemiluminescence of phagocytizing macrophages. Stimulation with CdCl2, a MT inducer, for three days before the injury increased the levels of MT in macrophages but decreased its liver levels. This effect was accompanied by a decrease in the intensity of the luminol-dependent but not lucigenin-dependent chemiluminescence. Administration of CdCl2 after the injury facilitated the induction of reduced MT in liver cells; however, its levels in macrophages remained low, and the intensity of their chemiluminescence did not decrease. The data suggest that MT is involved in oxidative metabolism and regulation of macrophage activity after combined radiation and thermal injury.

Topics: Acridines; Animals; Burns; Cadmium Chloride; Gamma Rays; Hot Temperature; Liver; Luminescent Measurements; Luminol; Macrophages, Peritoneal; Male; Metallothionein; Mice; Mice, Inbred Strains; Oxidation-Reduction; Phagocytosis