Liver Zn Research Articles

Serum alpha-tocopherol and immune function in yearling ewes supplemented with zinc and vitamin E.

Yearling Targhee ewes (n = 24; not pregnant or lactating) were used in a 2 x 2 factorial arrangement of treatments to determine the effects of supplemental vitamin E (0 IU [0vitE] vs 330 IU vitamin E x ewe(-1) x d(-1) [+vitE]) and Zn (0 mg [0Zn] vs 140 mg Zn x ewe(-1) x d(-1) [+Zn]) on serum alpha-tocopherol concentrations, antibodies to parainfluenza type 3 (PI3), ewe BW, Zn liver concentrations, and serum alkaline phosphatase activity. Ewes were managed as one group, grazed native pasture, and had ad libitum access to white salt and water. Ewes that received supplemental vitamin E were orally dosed every other day with 660 IU of DL-alpha-tocopherol acetate in a gelatin capsule beginning on d 1 and continuing to d 63 of the study. Ewes that received Zn supplement were orally dosed every other day with 280 mg of Availa-Zn 100 (Zinpro Corp., Eden Prairie, MN, IFN 6-32-054) in gelatin capsules for 63 d. All ewes were vaccinated with killed PI3 on d 22 and 42. No interactions were detected (P > 0.35); however, serum alpha-tocopherol concentrations and PI3 antibody titer dilutions changed (P = 0.001) over the length of the study. Ewe BW change, serum alkaline phosphatase activity, and liver Zn concentrations did not differ (P > 0.22) between 0Zn and +Zn or 0vitE and +vitE ewes. Serum a-tocopherol tended to be higher (P = 0.08) in +vitE than 0vitE ewes and was numerically higher (P = 0.16) in +Zn than 0Zn ewes. Antibody titer dilutions were higher (P = 0.06) in 0Zn than +Zn ewes and did not differ (P = 0.83) between 0vitE and +vitE ewes. These results indicate that high levels of supplemental Zn may have a tendency to improve serum alpha-tocopherol concentrations but may have negative impacts on humoral immune function.

Untersuchungen zur Eignung wildlebender Wanderratten (Rattus norvegicus) als Indikatoren der Schwermetallbelastung

Depot compartments which are the primary sites of pollutant enrichment in the organism can be used as bioindicators (targets) in order to identify a burden for certain elements. Background concentrations of eleven elements in tissues and organs of wild-living rats (Rattus norvegicus) obtained from a region (Euroregion Neisse, around the trilateral border region of Germany, Poland and the Czech Republic) distinguished by low to intermediate levels of environmental contaminations are given in part I of this work. In order to identify the most important depot compartments for certain elements, a body burden method was applied. Differences of affinity due to sex and age of analyzed rats are discussed, as are the suitability of specific organs and tissues with regard to bioaccumulation measurements concerning metals.The principal depot compartments for the heavy metals Cu, Mn, Cd (in adult rats) and Tl are the liver and kidneys, whereas the elements Ni, Sr, Pb (for adult animals) and Ti are more affinitivly to bones. Co and Zn displayed a more pronounced affinity towards tissues of the bones and liver. The analysis revealed large differences in Cd and Pb distributions both among young and adult rats, and with respect to sexes.It can be concluded that the distribution of the elements investigated in this study in free-living rats agrees with that in man, except for that of Ni. The above agreement gives proof of the possibility to use depot organs of rats for bioindication which was already mentioned in part I of this work (‘Sex and age-related quantification of Al, As, Cd, Co, Cu, Mn, Ni, Pb, Sr, Ti, Tl and Zn in liver, heart, lung, kidney, muscle, brain and bones and establishment of distribution patterns’).

EFFECTS OF PARAQUAT ON ESSENTIAL ANTIOXIDANT ELEMENTS IN OSTEOGENIC DISORDER SHIONOGI RAT

This study reports the effect of paraquat (PQ) on concentrations of four elements (Cu, Fe, Mg, Zn) in lung, kidney, spleen, liver, and heart of male osteogenic disorder Shionogi (ODS) rats, a strain not able to synthesize vitamin C. PQ significantly increased the Cu concentrations in lung, liver, and plasma, accompanied by a fall in renal levels. Fe levels were elevated in liver and spleen but lowered in plasma. PQ produced an increase in kidney Mg and a rise in liver Mg and Zn levels. Cardiac elemental levels were not affected by PQ treatment. PQ, a known oxidant, produced changes in tissue elements involved in antioxidant mechanisms.

Concentrations of Cadmium, Zinc, Copper, Iron, and Metallothionein in Liver and Kidney of Nonhuman Primates

To evaluate the species specificity of Cd accumulation and the relationship of Cd with other essential metals and metallothionein (MT), the concentrations of Cd, Zn, Cu, and Fe in the liver and kidney and the MT concentrations in the soluble fractions of the liver and kidney were determined in Cd-uncontaminated nonhuman primates (11 species, 26 individuals) kept in a zoo and two wild-caught Japanese macaques. The compositions of metal-binding proteins in the soluble fractions were also investigated by high-performance liquid chromatography (HPLC). The hepatic Cd concentration was 0.03-14.0 microg/g and the renal Cd concentration was 0.35-99.0 microg/g, both varying greatly and being higher in nonhuman primates, which were more closely related to man. The hepatic Zn concentration was 24.0-176 microg/g and the renal Zn concentration was 13.5-138 microg/g, showing 7- to 10-fold differences, and a correlation (r=0.558, p<0.01) was found between renal Zn and renal Cd concentrations. It was proved that in the liver, MT is more closely correlated with Zn (r=0.795, p<0.001) than with Cd (r=0.492, p<0.01) and that in the kidney MT is correlated with both Cd (r=0.784, p<0.001) and Zn (r=0.742, p<0.001). HPLC analysis of metals bound to MT-like protein in chimpanzees, de Brazza's monkeys, and Bolivian squirrel monkeys showed that more than 90% of Cd in both the liver and kidney, approx 40% of Zn in liver and 28-69% of Zn in kidney were bound to MT-like protein. The higher percentage Zn was bound to high-molecular protein.

Effect of melatonin treatment on serum and tissue zinc levels in rats

AbstractMelatonin (MEL) is the main neuro‐hormone of the pineal gland. The main physiological function of MEL is to modulate variations of the light‐dark cycle and seasonal periodicity on various physiological functions. Zinc (Zn) is required as a catalytic component for more than 200 enzymes and is a structural constituent of many proteins, hormones, neuropeptides, and receptors. In addition, tissue Zn levels have been found to be altered after pinealectomy in rats. Recent findings have shown that MEL can modulate Zn turnover. In the present study, we investigated the effect of MEL treatment on the tissue and serum Zn levels. Male Spraque–Dawley rats (n = 24) were used. Rats received seven daily subcutaneous injections of MEL (10 mg/kg). After 7 days, rats were decapitated at 10:00 a.m. and 02:00 a.m., which were the periods of lowest and highest serum MEL levels, respectively. Blood and tissue samples were collected, and Zn levels were measured by atomic absorption spectrophotometry. In conclusion, MEL increased Zn levels in the salivary glands and small intestine. Daytime liver Zn levels and nighttime serum Zn levels increased in MEL‐treated group. There was no significant difference in brain after MEL treatment. Nighttime serum MEL levels were higher than daytime in both control and MEL‐treated group. In addition, MEL levels in MEL‐treated groups were significantly higher than those of control groups. It is clear that there is a tight relationship between Zn and MEL. J. Trace Elem. Exp. Med. 15:1–8, 2002. © 2002 Wiley‐Liss, Inc.

Interaction of dietary zinc and growth implants on weight gain, carcass traits and zinc in tissues of growing beef steers and heifers

In two separate studies, 60 beef heifers (379 kg BW) and 60 beef steers (348 kg BW) were randomly assigned to six treatments in 2×3 factorial arrangements. The treatments were with or without Synovex ® implants combined with either a control diet or diets supplemented with 200 ppm Zn from ZnSO 4 or zinc methionine (Zn-Met). Near the mid-point of the feeding periods, cattle were vaccinated with a modified live virus and subsequent titers and concentrations of immunoglobulin G (IgG) were measured. Liver and blood samples were obtained 1 week prior to the start of the experiments and at intervals during the experiments. In experiment 1, average daily gains of beef heifers were ( P<0.05) affected by the interaction of implant and source of dietary Zn. Compared to control and ZnSO 4 treatments, supplementation with Zn-Met increased ( P<0.05) the concentration of Zn in serum. Antibody titers and concentrations of IgG in serum were highest ( P<0.05) in heifers fed ZnSO 4 compared to heifers fed the control or Zn-Met supplemented diets. The Synovex-H ® implant reduced the concentrations of Zn and Cu in liver. In experiment 2, Synovex-S ® implants improved ( P<0.05) weight gains of steers supplemented with 200 ppm dietary Zn from ZnSO 4 compared to non-implanted steers. However, the implant had no effect when Zn-Met was the dietary Zn source. The implant increased ( P<0.05) concentrations of Zn in liver of steers supplemented with 200 ppm dietary Zn and reduced Zn in liver of steers fed the control diet. Implanted steers had higher ( P<0.05) Cu status and IgG concentrations in serum than non-implanted steers. Steers supplemented with either ZnSO 4 or Zn-Met had greater ( P<0.05) concentrations of Zn in liver and plasma than steers fed the control diet. These results indicate both the level and source of Zn supplementation in diets of feedlot cattle affect their response to growth implants.

Concentrations and interactions of selected essential and non-essential elements in ringed seals and polar bears of arctic Alaska.

In this study, we evaluated concentrations of twelve essential and non-essential elements (As, Cd, Co, Cu, Pb, Mg, Mn, Hg, Mo, Se, Ag, and Zn) in tissues of ringed seals (Phoca hispida) and polar bears (Ursus maritimus) of arctic Alaska (USA). All samples were collected between 1995-97 in conjunction with subsistence harvests. The essential elements are reported to help develop reference ranges for health status determination and to help assess known or suspected interactions affecting toxicoses of cadmium (Cd) and mercury (Hg). In some tissues, Cd, Hg, and selenium (Se) were present at concentrations that have been associated with toxicoses in some domestic animals. Nevertheless, tissue levels of all elements were within ranges that have been reported previously in other pinnipeds and polar bears. Significant associations included: Cd with Zn or Cu; Cu with Zn or Ag; and Hg with Se, Zn, or Cu. This study found hepatic Hg:Se molar ratios to be lower than unity and different between the two species. Based upon significant differences in mean tissue elemental concentrations for polar bear versus ringed seal, we concluded that biomagnification factors (bear/seal) were significant for: Cu in liver and muscle; Pb in kidney; Se in kidney and muscle; Zn in liver and muscle; and Hg in liver. Possible explanations for observed elemental correlations (i.e., interactions) and ancillary mechanisms of Cd and Hg detoxification are discussed.

Dietary Zinc Deficiency and Repletion Modulate Metallothionein Immunolocalization and Concentration in Small Intestine and Liver of Rats

Metallothionein (MT) functions in zinc (Zn) homeostasis and dietary Zn affects tissue MT concentration. The objective of this study was to investigate the effects of dietary Zn deficiency and 24-h Zn repletion on MT immunolocalization and concentration in the small intestine and liver of growing rats. Three-week-old rats fed Zn-deficient diet (< 1 mg Zn/kg) for 16 d had no MT staining in either small intestine or liver. After 24-h Zn repletion with control diet (30 mg Zn/kg), strong MT staining was observed in intestinal Paneth cells and surface epithelial cells in the proliferative regions of villi. Pair-fed control rats had strong MT staining in liver that was localized around central veins. After 24-h energy repletion, the hepatic MT staining diminished. Furthermore, Zn-deficient rats had significantly reduced intestinal (57%) and hepatic (61%) MT concentrations but unaffected Zn concentrations compared with controls that consumed food ad libitum. Zn repletion for 24 h restored intestinal and hepatic MT concentrations and reduced hepatic Zn concentration. Pair-fed control rats had elevated MT concentration in liver that was normalized by energy repletion. There was a significant positive correlation between tissue Zn and MT concentrations in liver (r = 0.60, P = 0.0001), but not in small intestine. In summary, MT immunolocalization and concentration in rat small intestine and liver were responsive to changes in Zn status, supporting the role of MT in Zn metabolism. Cell-type-specific localization of MT in small intestine after dietary Zn manipulations indicates a function of Zn and MT in gut immunity and intestinal mucosal turnover, and the pattern of hepatic MT distribution with energy restriction may be linked to detoxification processes.

Trace Mineral Supplementation in the Presence of Antagonists on Growth Performance, Health, and Carcass Characteristics of Transport-Stressed Calves

Crossbred steer calves (n = 64) were used in a 2 × 2 factorial arrangement to evaluate two levels of organic trace minerals and two levels of inorganic trace minerals. Calves were fed 28 d on the ranch in two pens of eight head per treatment before a simulated transport stress. After being loaded, hauled 129 km, unloaded with an overnight stand without feed and water, and reloaded, they were shipped to the Colorado State University (CSU) research feedyard in Fort Collins and placed in 64 individual pens. Calves fed the organic low level and inorganic high level trace minerals gained better (P<0.05) the first 28 d than did calves fed the organic high level or inorganic low level trace minerals. Overall growth performance was not influenced by trace mineral types or levels. Longissimus area was greater (P<0.05) for calves fed the low level organic trace minerals compared with that for calves fed the low level inorganic trace minerals. Eosinophils (d 28) were higher (P<0.05) for calves fed the organic high level trace minerals compared with calves fed inorganic low level trace minerals. Infectious bovine rhinotracheitis (IBR) and parainfluenza (PI3) titers were not influenced by trace minerals. Red blood cells and packed cell volume were higher (P<0.05) for calves fed low level trace minerals regardless of trace mineral type. Liver Co was increased (P<0.05) at the 28-d sampling when inorganic trace minerals were fed. Liver Co was highest (P<0.05) at the 168- d sampling for calves fed low level inorganic trace minerals followed by calves fed organic high level trace minerals. Liver Fe was lower (P<0.05) in calves at the d-168 sampling when organic trace minerals were fed. Liver Zn was elevated (P<0.05) by d 28 by feeding the inorganic low level trace minerals, and by d-168, liver Zn was higher (P<0.05) for calves fed the low levels of trace minerals. Initial growth performance was maintained by either supplementing organic trace minerals or elevating dietary inorganic trace minerals when confronted with high dietary Fe, S, or Mo.

Hepatic and renal metallothionein induction by an oral equimolar dose of zinc, cadmium or mercury in mice

The hepatic and the renal subcellular distribution of zinc, cadmium or mercury and induction of tissue metallothionein (MT) at 24, 48 and 72 h following an oral equimolar dose (15 μmol metal/kg) of zinc (II) chloride, cadmium (II) chloride or mercury (II) chloride in male albino mice were investigated. There was a moderate increase in hepatic and renal zinc levels mainly in their nuclear mitochondrial fraction (NMF) 24 h post zinc chloride administration. Subsequently, the hepatic zinc increased and the renal zinc declined with time. The zinc-induced hepatic MT level was maximum at 48 h, which decreased slightly thereafter, while there was no marked increase in renal MT level at any time interval. The cadmium was equally distributed in liver and kidney more in their supernatant cytosol fraction (SCF) than in their NMF at 24 h after a dose of cadmium chloride. The cadmium levels showed a decreasing trend in hepatic fractions and an increasing trend in renal fractions with time. The cadmium-induced hepatic and renal MT were substantial at 24 h post cadmium administration, the former decreased thereafter while the latter enhanced at 48 h before declining. The accumulation of mercury in kidney was 1.5 times that in liver, which was localised more in their SCF than in their NMF at 24 h in response to a dose of mercuric chloride. The mercury levels of hepatic and renal subcellular fractions started declining after 24 h and at 72 h they were significantly lower. The induction of hepatic and renal MT was maximum at 24 h after mercuric chloride administration, which declined thereafter concomitant with the decrease in their mercury levels. However, the MT levels in both the organs remained considerably higher than in normal animals at 72 h post exposure. The results show that the accumulation of metal in liver and kidney follows the order: Hg>Cd>Zn and the induction of MT follows Hg>Cd>Zn in liver and Cd>Hg>Zn in kidney. The alterations in zinc and copper homeostasis were more marked in liver than in kidney and follows the order: Hg>Cd>Zn.

Heavy metal contents in Egyptian meat and the role of detergent washing on their levels

Pollution of the environment with heavy metals is a serious problem, which is recognized in most countries of the world. Metals accumulate in the liver, and particularly in the kidneys. The present study provides information about the concentrations of metals in animal organs from both rural and industrial areas. It was surprising that the Pb, Cd, Zn, Cu, Mn and Fe contents in muscle, liver, kidney, heart and spleen in industrial areas were higher than in the same organs of rural areas. Lead concentrations in bovine liver and kidney, in buffalo, elk, sheep and goat kidneys as well as Cd in elk liver and kidneys were higher in the present study than the recommended values. The effect of washing for bovine muscle, liver and kidney using tap water and other detergent solutions on the metals was studied. Washing by only tap water was less effective than the other detergent. The results indicate the efficient role of washing by acidic detergent in the reduction of Pb, Cd and Zn from naturally contaminated meat compared with neutral and alkaline detergent.

Bioavailability of metals in stream food webs and hazards to brook trout (Salvelinus fontinalis) in the upper Animas River watershed, Colorado.

The water quality, habitats, and biota of streams in the upper Animas River watershed of Colorado, USA, are affected by metal contamination associated with acid drainage. We determined metal concentrations in components of the food web of the Animas River and its tributaries-periphyton (aufwuchs), benthic invertebrates, and livers of brook trout (Salvelinus fontinalis)-and evaluated pathways of metal exposure and hazards of metal toxicity to stream biota. Concentrations of the toxic metals cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in periphyton, benthic invertebrates, and trout livers from one or more sites in the upper Animas River were significantly greater than those from reference sites. Periphyton from sites downstream from mixing zones of acid and neutral waters had elevated concentrations of aluminum (Al) and iron (Fe) reflecting deposition of colloidal Fe and Al oxides, and reduced algal biomass. Metal concentrations in benthic invertebrates reflected differences in feeding habits and body size among taxa, with greatest concentrations of Zn, Cu, and Cd in the small mayfly Rhithrogena, which feeds on periphyton, and greatest concentrations of Pb in the small stonefly Zapada, a detritivore. Concentrations of Zn and Pb decreased across each trophic linkage, whereas concentrations of Cu and Cd were similar across several trophic levels, suggesting that Cu and Cd were more efficiently transferred via dietary exposure. Concentrations of Cu in invertebrates and trout livers were more closely associated with impacts on trout populations and invertebrate communities than were concentrations of Zn, Cd, or Pb. Copper concentrations in livers of brook trout from the upper Animas River were substantially greater than background concentrations and approached levels associated with reduced brook trout populations in field studies and with toxic effects on other salmonids in laboratory studies. These results indicate that bioaccumulation and transfer of metals in stream food webs are significant components of metal exposure for stream biota of the upper Animas River watershed and suggest that chronic toxicity of Cu is an important factor limiting the distribution and abundance of brook trout populations in the watershed.

Accumulation of copper and generation of hydroxyl radicals of hepatocellular carcinoma

Aims: This study evaluated the connection between the progression of hepatic fibrosis and trace metals, the distribution profiles of copper(Cu) and Zinc (Zn) and the generation of hydroxyl radicals from Cu- metallothionein (MT) purified from human hepatocellular carcinoma (HCC). Methods: We measured the metal contents in HCC tissue and liver parenchyma in patients with HCC. The content of metals in the liver was measured by particle induced X-ray emission (PIXE). Distribution profiles of Cu and Zn in human liver was evaluated by high-performance liquid chromatography (HPLC). The generation of hydroxyl radicals was measured by electron spin resonance (ESR) spin-trapping technique. Results: Hepatic copper content increased with the progression of hepatic fibrosis. Copper level in liver parenchyma was higher in patients with HCC than in those without HCC (p &lt; 0.01). MT was mainly present as Zn-MT in normal liver, Cu,Zn-MT in surrounding liver parenchyma and Cu-MT in HCC (p &lt; 0.01). The signal intensity of the ESR spectrum in HCC was stronger than those in normal liver and surrounding liver parenchyma. Conclusions: Copper accumulation in the liver parenchyma seems to relate to hepatocarcinogenesis.

Zinc and copper status in ewes supplemented with sulfate- and amino acid-complexed forms of zinc and copper.

Thirty 6-yr-old Targhee ewes were randomly allotted to one of five supplemental treatments to evaluate supplementation effects on liver and fecal Zn and Cu concentrations and serum alkaline phosphatase activity: 1) control, 2) Zn complex, 3) Zn and Cu (ZnCu) complex, 4) Zn sulfate, and 5) ZnCu sulfates. Supplements were administered daily in gelatin capsules for 56 d. Liver biopsies and serum samples were collected every 14 d starting on d 0. Supplemental Zn and Cu levels were formulated to provide 90 mg/kg Zn and 10 mg/kg Cu, respectively, on a daily dry matter intake basis. Form (complex vs sulfate) x type (Zn vs ZnCu) interactions were not detected (P > 0.35). Therefore, contrast statements were used to make the following treatment comparisons: 1) control vs supplement, 2) Zn vs ZnCu, and 3) complex vs sulfate. Ewe BW at the end of the study (P = 0.09) and ewe BW change from beginning to end of the study (P = 0.07) were greater for supplemented than control ewes. Body weight and BW change did not differ between sulfate and complex (P > 0.39) or Zn- and ZnCu- (P > 0.40) supplemented ewes. Liver Cu concentrations did not differ (P = 0.41) between control and supplemented ewes. Liver Cu concentrations were higher (P < 0.10) for ewes supplemented with ZnCu than Zn and complex than sulfate forms of supplement. Liver Zn concentration tended (P = 0.13) to be higher in ZnCu than Zn-supplemented ewes. Liver and fecal Zn concentration were higher (P < 0.06) in ewes fed complex than sulfate supplements. However, serum alkaline phosphatase activity tended (P = 0.12) to be greater in ewes fed sulfate than complex supplements. Supplementing mature ewes with complexed minerals resulted in higher concentrations of Zn and Cu in the liver. In addition, supplemental Cu tended to increase concentrations of Zn in the livers of ewes; however, high levels of supplemental Zn did not negatively impact liver Cu concentrations.

Bioavailability of zinc and its binding to casein in milks and formulas

Differences in zinc bioavailability among milk and formulas may be attributed to binding of zinc to various ligands. We determined the distribution of zinc and protein at different pHs and zinc and calcium concentrations. We used radiolabelled cow's milk, human milk, whey-predominant (WPF) and casein-predominant (CPF) infant formula. Lowering the pH changed zinc and protein distribution: zinc shifted from pellet (casein) to whey in cow's milk, from fat to whey in human milk and from fat and pellet to whey in formulas. Protein shifted from whey to pellet in human milk and from whey and pellet to fat in formulas. Increasing zinc and calcium concentrations shifted protein and zinc from pellet to whey for cow's milk and from whey and pellet to fat for the formulas. Protein distribution was not affected by calcium or zinc addition in human milk or CPF, while zinc shifted from whey to fat in human milk and from fat and pellet to whey in CPF. Zinc and calcium binding to isolated bovine or human casein increased with pH. At 500 mg/L of zinc, bovine casein bound 32.0 +/- 1.8 and human casein 10.0 +/- 0.9 mg zinc/g protein. At 500 mg/L of calcium, calcium was preferentially bound over zinc. Adding calcium and zinc resulted in 32.0 +/- 1.8 mg zinc/g bound to bovine casein and 17.0 +/- 0.8 mg zinc/g to human casein, while calcium binding was low. Suckling rat pups dosed with 65Zn labelled infant diets were killed and individual tissues were gamma counted. Lower zinc bioavailability was found for bovine milk at pH = 4.0 (%65Zn in liver = 18.7+1.4) when compared to WPF (22.8 +/- 1.6) or human milk (26.9 +/- 0.8). Lowering the pH further decreased zinc bioavailability from human milk, but not from cow's milk or WPF. Knowledge of the compounds binding minerals and trace elements in infant formulas is essential for optimizing zinc bioavailability.

Metallothionein in Mice Reduces Intestinal Zinc Loss during Acute Endotoxin Inflammation, but Not during Starvation or Dietary Zinc Restriction

Normal metallothionein [(MT)+/+] and MT-null (MT-/-) mice were used to examine the influence of MT on Zn retention and the metabolic consequences of 2 d food deprivation, with and without inflammation induced by intraperitoneal injection of bacterial endotoxin lipopolysaccharide (LPS). LPS reduced fecal Zn concentration in MT+/+ mice from 5.9 +/- 0.2 micromol/g on d 1 to 2.2 +/- 0.2 micromol/g on d 2, but not in MT-/- mice, 5.9 +/- 0.2 and 5.7 +/- 0. 5 micromol/g, respectively. MT+/+ mice fed an 8 mg Zn/kg diet and injected with LPS excreted 40% less Zn over 2 d than their MT-/- counterparts. Starvation for 2 d did not lower fecal Zn concentration in either genotype, although in MT+/+ mice, urinary Zn excretion was reduced from 12.7 +/- 1.3 nmol on d 1 to 5.9 +/- 1.8 nmol on d 2 and plasma Zn concentration was lowered to 9.8 +/- 0.4 micromol/L. Zn was not reduced in urine or plasma of MT-/- mice, with respective values of 10.8 +/- 2.0 nmol on d 1, 9.3 +/- 2.9 nmol on d 2 and 13.0 +/- 1.0 micromol/L. LPS injection resulted in much higher total liver Zn (677 +/- 27 nmol) and MT (106 +/- 2 nmol Cd bound/g) than starvation (Zn = 405 +/- 21, MT = 9 +/- 3) in MT+/+ mice after 2 d, but did not further reduce urinary Zn. LPS-injected MT-/- mice had no rise in liver Zn or fall in plasma and urine Zn. MT-/- mice fed a Zn-deficient (0.8 mg Zn/kg) diet lost 10% of body weight over 25 d compared with no loss in MT+/+ mice. Despite this, MT-/- mice excreted no more Zn via the gut than did MT+/+ mice. In summary, MT inhibits intestinal Zn loss when highly expressed. When uninduced, typically during Zn deficiency, MT appears to conserve Zn and body mass by reducing only urinary and other nonintestinal Zn losses.

Ethanol Decreases Zinc Transfer to the Fetus in Normal but Not Metallothionein‐Null Mice

Ethanol causes significant teratogenicity in normal (MT+/+) but not metallothionein-null (MT-/-) fetuses. Impaired maternal fetal zinc (Zn) transfer is indicated, because ethanol significantly reduces plasma Zn concentrations in MT+/+ dams while increasing concentrations in MT-/- dams. In this study we examined maternal-fetal Zn homeostasis in response to ethanol in MT+/+ and MT-/- mice and the origins of the increase in plasma Zn in MT-/- mice. Mice were treated with saline or ethanol (0.015 ml/g intraperitoneally at 0 and 4 hr) on day 12 of gestation. An additional subcutaneous injection of 65Zn tracer was administered after the second ethanol injection before mice were killed 3 hr later. Maternal liver MT levels were not different between ethanol and saline MT+/+ mice. Both liver Zn and 65Zn levels were higher in MT+/+ mice. Plasma Zn concentrations were higher in MT-/- mice, with MT-/- ethanol-treated mice having levels greater than those of MT-/- saline-treated controls. MT+/+ ethanol-treated fetuses exhibited lower 65Zn transfer and whole Zn concentrations compared with MT+/+ and MT-/- saline and MT-/- ethanol fetuses. So we could examine changes in plasma Zn after ethanol treatment, MT+/+ and MT-/- mice were injected with 65Zn 3 days before they received ethanol treatment. Muscle and skin showed a decrease in 65Zn retention in both genotypes over 3 hr. There was a trend toward greater 65Zn release from skin and muscle at an earlier time in MT-/- mice: 24% vs. 2% decrease (MT-/- vs. MT+/+) for muscle and 28% vs. 15% decrease (MT-/- vs. MT+/+) for skin at 2 hr. The results show (a) that ethanol interferes with the transfer of Zn to the fetus, and that this is MT dependent, and (b) that the increase in plasma Zn seen in MT-/- mice after ethanol administration is a result of Zn release from the skin and muscle, in the absence of hepatic Zn sequestration.

Ethanol Decreases Zinc Transfer to the Fetus in Normal but Not Metallothionein-Null Mice

Background: Ethanol causes significant teratogenicity in normal (MT+/+) but not metallothionein-null (MT−/−) fetuses. Impaired maternal fetal zinc (Zn) transfer is indicated, because ethanol significantly reduces plasma Zn concentrations in MT+/+ dams while increasing concentrations in MT−/− dams. In this study we examined maternal-fetal Zn homeostasis in response to ethanol in MT+/+ and MT−/− mice and the origins of the increase in plasma Zn in MT−/− mice. Methods and Results: Mice were treated with saline or ethanol (0.015 ml/g intraperitoneally at 0 and 4 hr) on day 12 of gestation. An additional subcutaneous injection of 65Zn tracer was administered after the second ethanol injection before mice were killed 3 hr later. Maternal liver MT levels were not different between ethanol and saline MT+/+ mice. Both liver Zn and 65Zn levels were higher in MT+/+ mice. Plasma Zn concentrations were higher in MT−/− mice, with MT−/− ethanol-treated mice having levels greater than those of MT−/− saline-treated controls. MT+/+ ethanol-treated fetuses exhibited lower 65Zn transfer and whole Zn concentrations compared with MT+/+ and MT−/− saline and MT−/− ethanol fetuses. So we could examine changes in plasma Zn after ethanol treatment, MT+/+ and MT−/− mice were injected with 65Zn 3 days before they received ethanol treatment. Muscle and skin showed a decrease in 65Zn retention in both genotypes over 3 hr. There was a trend toward greater 65Zn release from skin and muscle at an earlier time in MT−/− mice: 24% vs. 2% decrease (MT−/− vs. MT+/+) for muscle and 28% vs. 15% decrease (MT−/− vs. MT+/+) for skin at 2 hr. Conclusions: The results show (a) that ethanol interferes with the transfer of Zn to the fetus, and that this is MT dependent, and (b) that the increase in plasma Zn seen in MT−/− mice after ethanol administration is a result of Zn release from the skin and muscle, in the absence of hepatic Zn sequestration.

Variations in Metallothionein, Zn, Cu, and Fe Concentrations and Ceruloplasmin Activity in Pregnant Rat Dams and Their Fetuses

Growing rat fetuses have great need for Zn, Cu, and Fe. In fetal livers (FL) large accumulations of Zn and Cu connected with increased metallothionein (MT) synthesis take place. In dams, serum changes in metals concentrations with increased ceruloplasmin (Cp) activity are observed. The aim of this study was to determine (1) mutual relationships in the accumulation of MT, Zn, Cu, and Fe in fetal livers; (2) changes in Zn, Cu, and Fe concentrations in dam serum; and (3) the day with the maximum Cp activity. Sections of rat dams were taken on 16th–21st day of gestation, twice a day, and MT, Zn, Cu, and Fe concentrations in liver, spleen, kidneys, and placenta of dams and in liver and brain in fetuses were determined. In fetal livers high correlations between MT and Zn and between Zn and Cu were obtained. The investigated Cp activity was always high, reaching its maximum on the 20th day and minimum on the 21st day. Significant correlation between Cp activity and Cu concentration in dam serum was also revealed. In conclusion it is suggested that Zn accumulation in FL is strictly connected with MT synthesis but Cu content in FL is rather dependent on Cp activity in dam serum. Iron accumulation in fetal livers is connected with the diminution of iron concentrations in dam serum.

Infra-red heating as an alternative technique for fast sample preparation

A procedure for sample preparation was investigated in this work using infra-red radiation generated by tungsten lamps for fast heating of an acidic sample suspension contained in a glass flask. The main advantages of the developed procedure are its simplicity and low-cost. Additionally the dilute acid solution is heated in less than 60 s and the total sample preparation is performed in less than 5 min. The proposed procedure is suitable for trace analysis and it can be easily implemented. The preliminary investigations focus on the determination of Cu, Fe, Mn, and Zn in bovine liver and apple leaves as standard reference materials. All results are in agreement at a 95% confidence level. Copper and Mn were also determined in a sample of bovine liver without any sample pretreatment or after a freeze-drying step for comparison. For this sample, the results were validated using a conventional microwave-assisted closed vessel procedure.