Vincenzo Albergoni

Zinc Therapy Increases Duodenal Concentrations of Metallothionein and Iron in Wilson's Disease Patients

Objective:Wilsons disease is effectively treated by zinc administration which, in vitro, increases metallothionein concentrations. To ascertain whether the latter also occurs in humans we measured metallothionein and trace element concentrations in the duodenal mucosa of 15 Wilsons disease patients: 12 treated with zinc sulphate, two treated with penicillamine, and one not yet on treatment. The control group consisted of 17 patients with dyspepsia, who underwent the same study protocol.Methods:Metallothionein and trace element concentrations were measured in duodenal mucosa biopsies according to the silver-saturation hemolysate method and atomic absorption spectrophotometry.Results:Metallothionein concentrations increased by 1500% after zinc and 150% after penicillamine in Wilsons disease patients, with respect to controls who had negative endoscopy and Wilsons disease patients who were not treated. A significant correlation was found between metallothionein and duodenal zinc concentrations. Mucosal iron concentration increased in Wilsons disease patients whether they were treated with zinc or penicillamine. Duodenum with duodenitis also had significantly increased iron levels compared with normal duodenum.Conclusions:Zinc administration increases intestinal metallothionein in Wilsons disease patients. The blockade of copper absorption and its elimination in the stools on desquamation of the intestinal cells probably explains one of the mechanisms underlying the effect of zinc treatment. Despite normal endoscopy, Wilsons disease patients present increased mucosal iron concentrations similar to those in controls with duodenitis. Metallothionein may therefore prevent oxidative damage caused by metal toxicity.

Response to heavy metals in organisms—I. Excretion and accumulation of physiological and non physiological metals in Euglena gracilis☆

Abstract Euglena gracilis was cultured with different concentrations of an essential metal and a non essential one: Cu and Cd. Cu even at high concentrations did not affect the growth rate, while Cd reduced it according to the concentration used. Cu concentration stayed always lower in the cells than in the medium, instead Cd was accumulated in the cells. From cells and medium of cultures treated with copper a glycopeptide which chelated copper and zinc was isolated. It was present in the control culture too, but it linked only Zn; its molecular weight is lower than 10,000 D. From cells cultured with Cd a compound of a very high molecular weight (higher than 100,000 D) was isolated: it linked Cd and Zn. The concentration of Zn in the medium and in the cells linked to the compounds is also discussed, and a model is proposed for regulation of physiological metals in organisms; it may explain how detoxification relates to regulation of heavy metals.

Effect and possible role of Zn treatment in LEC rats, an animal model of Wilson's disease

The effect of oral zinc (Zn) treatment was studied in the liver, kidneys and intestine of Long-Evans Cinnamon (LEC) rats in relation to metals interaction and concentration of metallothionein (MT) and glutathione (GSH). We also investigated the change in the activity of antioxidant enzymes and determined the biochemical profile in the blood and metal levels in urine. We showed that the Zn-treated group had higher levels of MT in the hepatic and intestinal cells compared to both untreated and basal groups. Tissue Zn concentrations were significantly higher in the Zn-treated group compared to those untreated and basal, whereas Cu and Fe concentrations decreased. The antioxidant enzyme activities in the Zn-treated group did not change significantly with respect to those in the basal group, except for hepatic glutathione peroxidase activity. Moreover, the biochemical data in the blood of Zn-treated group clearly ascertain no liver damage. These observations suggest an important role for Zn in relation not only to its ability to compete with other metals at the level of absorption in the gastrointestinal tract producing a decrease in the hepatic and renal Cu and Fe deposits, but also to MT induction as free radical scavenger.

Cadmium bioaccumulation studies in the freshwater molluscs Anodonta cygnea and Unio elongatulus

Abstract 1. The effects of cadmium exposure have been studied in two freshwater bivalves, A. cygnea and U. elongatulus . 2. Cadium exposure induces an unremarkable cadmium uptake in the tissues of both the organisms. Thus the low metal concentration in the tissues together with the absence of suffering seem to indicate the presence of some kind of regulation. 3. Cadmium exposure has little effect on copper and zinc levels and distribution indicating in these organisms the presence of little interaction between cadmium and divalent essential metals. 4. The percentage distribution of cadmium, copper and zinc between the two main fractions obtained from Sephadex G-75 varies with metal, organism and tissue suggesting that high molecular weight metal chelating compounds are actually present in the organisms. 5. The detoxication capabilities of different organisms are discussed in relation to the differences found in two closely related freshwater animals.

Relationship between metallothionein and metal contents in red-blooded and white-blooded Antarctic teleosts

Abstract Metal bioaccumulation and metallothionein were investigated in different organs of the red-blooded teleost, Trematomus bernacchii and the haemoglobinless Chionodraco hamatus. Specimens of the two Antarctic fish were sampled from Terra Nova Bay (Ross Sea), and their levels of Cd, Cu and Zn in homogenates and in soluble fractions of liver, muscle, gills, heart and plasma were determined. Dosages of metallothioneins (MTs) or MT-like proteins were assayed by the silver saturation method in soluble fractions of the same organs. In both T. bernacchii and C. hamatus the highest MT contents were found in liver. Hepatic MT and Cd, Cu and Zn concentrations correlated positively in T. bernacchii, whereas in C. hamatus hepatic MT showed a positive correlation only with Cd. Positive correlations were also found between Cd and MT in gills of the two species. A metal-binding protein containing a high percentage of cysteine from C. hamatus was purified and compared with the MT from T. bernacchii and mammals.

Effect of zinc supplementation on metallothionein, copper, and zinc concentration in various tissues of copper-loaded rats.

The present study was designed to investigate the effects of Zn administration on metallothionein concentrations in the liver, kidney, and intestine of copper-loaded rats. Male CD rats were fed a diet containing 12 mg Cu and 67 mg Zn/kg body wt. They were divided into either acute or chronic experimental protocols. Rats undergoing acute experiments received daily ip injections of either Cu (3 mg/kg body wt) or Zn (10 mg/kg body wt) for 3 d. Chronic experiments were carried out on rats receiving Cu ip injections on d 1, 2, 3, 10, 17, and 24, Cu injections plus a Zn-supplemented diet containing 5 g Zn/kg solid diet, or a Zn-supplemented diet alone. Rats injected Zn or Cu had increased MT concentrations in liver and kidney. Zn produced the most important effects and the liver was the most responsive organ. Rats fed a Zn-supplemented diet had significantly higher MT concentrations in liver and intestine with respect to controls. Increased MT synthesis in the liver may contribute to copper detoxification; the hypothesis of copper entrapment in enterocytes cannot be confirmed.

Efficacy of zinc supplementation in preventing acute hepatitis in Long–Evans Cinnamon rats

Objectives: Objectives: Long–Evans Cinnamon (LEC) rats are characterized by an abnormal hepatic deposition of copper (Cu) due to a lack of the Cu‐transporter P‐type adenosine triphosphatase: accordingly, the strain is a good animal model of Wilsons disease. The effect of oral zinc (Zn) acetate treatment on the development of acute hepatitis and the biochemical parameters of Cu‐induced liver damage was studied in 5‐week‐old LEC rats (n=52).

Regulation and subcellular distribution of copper in the freshwater molluscs Anodonta cygnea (L.) and Unio elongatulus (Pf.)

1. The effects of copper exposure have been studied in two freshwater bivalves, Anodonta cygnea and Unio elongatulus. 2. Copper exposure induces a small degree of copper accumulation in both organisms leading to the hypothesis of a regulatory mechanism for copper intake. 3. Copper distribution in the particulate fractions is affected by copper treatments, with an increase in the lysosome-enriched fraction. 4. Copper exposure does not affect zinc levels and distribution. 5. The percentage distribution of copper and zinc among the eytosol fractions obtained from Sephadex G-75 varies with organism, tissue and copper exposure suggesting that high molecular weight chelating compounds are actually present in the two organisms.

Interactions between metals in rat liver and kidney: localization of metallothionein.

The interactions between two essential metals, Cu and Zn, and the localization and concentration of metallothionein have been studied in rat liver and kidney. Rats receiving daily intraperitoneal injections of Cu for 3 days, or Zn for 2 days, or Cu for 3 days followed by Zn for 2 days, were sacrificed 24, 72, 120 h after the final injection. Our data indicate that Cu and Zn are both good inductors of metallothionein synthesis in rat tissues. Synergism between Cu and Zn in metallothionein synthesis was also observed as indicated by immunocytochemical experiments and chemical analysis. Moreover, in rats injected with Cu followed by Zn, the localization of metallothionein and the concentrations of both metallothionein and metal differed over time according to the organs considered. In rat kidney, a delay in the excretory process was also observed and metallothionein was present 120 h after the last injection.

Effects of cadmium on catfish, Ictalurus melas, humoralimmune response

Abstract Catfish ( I. melas ) were exposed to 10, 20 or 30 μ g 1 −1 of cadmium (CdCl 2 ) toassess its in vivo effects on the humoral immune response. After one week of cadmium exposure, the titer of total non-specific immunoglobulins was remarkably reduced but, after 2 weeks of exposure the IgM titer increased, and no differences between treated and control fish could be observed. Immunization of catfish with sheep red blood cells (SRBC) was also performed to assess the effect of cadmium on the immune response to a specific antigen. Fish exposed to cadmium (20 μ g 1 −1 ) required a shorter period to reach the peak of IgM anti-SRBC titer; moreover, fish exposed to Cd for 2 weeks before immunization reached peak antibody response more quickly and also revealed a remarkable increase in antibody titer.