Zinc, copper, and iron metabolism during porcine fetal development

Zinc, copper, and iron levels in maternal and fetal pig tissues and fluids were measured starting on d 30 of gestation and continuing to term (d 114) at 10-d intervals. Fetal hematocrit increased from a low of 19% on d 30 to 32% by d 50, after which it remained above 30% to term. Amniotic fluid zinc, copper, and iron all reached maximal levels by d 60 of gestation. Maternal serum zinc levels fluctuated little during gestation, but fetal serum zinc concentration was significantly elevated above maternal levels during the second trimester. Fetal serum copper levels were significantly lower than maternal values throughout gestation and this was also the case for ceruloplasmin oxidase activity. Maternal serum iron reached its lowest level by d 80 of gestation when rate of transfer of iron to the developing fetuses was high. Fetal serum iron declined throughout gestation, reaching its lowest level on d 100. In general, fetal liver concentrations of zinc, copper, and iron were higher than the corresponding maternal values throughout gestation. Distinct increases were noted for fetal hepatic zinc and copper concentrations during the second trimester of pregnancy and these were accompanied by increases in cytosolic and metallothionein-bound zinc and copper levels. Maternal hepatic iron declined during the second trimester, reaching its lowest point on d 80, indicative of the shunting of maternal iron reserves to fetal tissues. Fetal kidney metal levels did not demonstrate any distinctive developmental patterns with respect to zinc, copper, or iron concentrations, but a general accumulation of each metal was observed as gestation progressed. The results of this study highlight some of the distinct changes occurring in the metabolism of zinc, copper, and iron in both maternal and fetal tissues and fluids during gestation in the pig. Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other suitable products.     

Zinc and copper in human cerebrospinal fluid

Zinc and copper have been estimated in CSF of 14 normal volunteers, nine men and five women. Zinc was analyzed by limited-aspiration flame atomic absorption spectrophotometry using a deuterium continuum light source. Copper was analyzed in 0.1% HNO₃ by flameless atomic absorption spectrophotometry with a graphite cuvette on a flameless atomizer. Recovery of added zinc varied less than 5% and that of the added copper varied less than 8%. CSF zinc was 31.5±19.8 μg/L (mean ± 1 SD); CSF copper, 7.5±3.1 μ/L. Values obtained for CSF zinc are about 1/2 those we and others obtained previously, the decrease related almost exclusively to removal of interference by the CSF matrix, which produced spuriously elevated values without use of the deuterium light source. Values obtained for CSF copper were approximately one-tenth those we and others had obtained previously. The decrease related, in part, to the removal of matrix effects, but also to improvement of the signal-to-noise ratio present in other techniques.     

Reference ranges of copper and zinc and the prevalence of their deficiencies in an Arab population aged 15-80 years

Serum concentrations of copper and zinc were measured by flame atomic absorption spectrophotometry in 560 Kuwaitis aged from 15 to 80 yr who were in apparent good health to establish reference ranges and determine the prevalence of the deficiency of the trace metals. Zinc/copper ratios were derived by calculation. Because the mean +/- SD (microM) for copper in females (24.9 +/- 7) was significantly higher (p<0.0001) than in males (21.0 +/- 5.8) and vice versa for zinc (17.0 +/- 3.5 [males] vs 15.5 +/- 3.4 [females]) and zinc/copper ratios (0.87 +/- 0.28 [males] vs 0.67 +/- 0.27 [females]), gender-specific reference ranges were established in addition to reference ranges for the total population. The reference range for zinc was closer to those reported for other populations than was copper. Body mass index (BMI) and copper values were lower and the zinc/copper ratio was higher in the young (15-24 yr) compared to the older subjects. Copper concentrations were positively associated with BMI values (r=0.302, p<0.0001). Smokers had significantly lower (p=0.011) BMI than nonsmokers. The prevalence of copper and zinc deficiency, 0.36% and 0.53%, respectively, was low. Generally, the values for serum copper and zinc obtained for the Kuwaiti population studied suggest adequate dietary intake of the trace metals.     

Iron and zinc status in rats with diet-induced marginal deficiency of vitamin A and/or copper

The hypothesis was tested that there are interactions of marginal copper and vitamin A deficiency regarding iron and zinc status. Copper restriction (1 vs 5 mg Cu/kg diet) significantly lowered copper concentrations in plasma and tissues of rats and reduced blood hemoglobin, hematocrit, and iron concentrations in tibia and femur, but raised iron concentrations in liver. Vitamin A restriction (0 vs 4000 IU vitamin A/kg diet) reduced plasma retinol concentrations and induced a fall of blood hemoglobin and hematocrit. Neither copper nor vitamin A restriction for up to 42 d affected feed intake and body wt gain. There were no interrelated effects of vitamin A and copper deficiency on iron status. Copper deficiency slightly depressed liver, spleen, and kidney zinc concentrations. Vitamin A deficiency lowered zinc concentrations in heart, but only when the diets were deficient in copper.     

Effects of copper aspirinate and aspirin on tissue copper,zinc, and iron concentrations following chronic oral treatment in the adjuvant arthritic rat

Concentrations of copper, zinc, and iron were analyzed and compared in a number of tissues of adjuvant arthritic rats following 22 d of chronic treatment (per os) with either vehicle, aspirin or copper aspirinate, at doses of 100 mg/kg, 200 mg/kg, or 400 mg/kg. Such chronic treatment resulted in a negative balance in copper, zinc, and iron in many tissues. Among the tissues examined, liver and kidney exhibited the greatest changes in metal concentrations; brain and skeletal muscle exhibited the least. Arthritis-induced changes in the concentrations of all three metals in the liver were reversed upon treatment with aspirin. Treatment with copper aspirinate, on the other hand, resulted in an extremely high accumulation of copper in the liver. Arthritis-induced changes in copper, zinc, and iron concentrations in the pancreas and copper concentration in the plasma were generally not reversed upon treatment with either aspirin or copper aspirinate. Among the three metals examined, the degree of change observed as a result of drug treatments was greatest for iron and least for zinc. Finally, it appeared that the effects of aspirin and copper aspirinate on tissue metal concentrations were independent of the antiarthritic effects of these compounds.     

Stimulated release of exogenous GABA and glutamate from cerebral cortical synaptosomes and brain slices by bis (acetato) tetrakis (imidazole) copper(II) complex

Severe matermal zinc deficiency has a devastating effect on pregnancy outcome. Studies of humans and experimental animals show that matermal zinc deficiency can cause infertility, prolonged labor, intrauterine growth retardation, teratogenesis, severe immunological deficiencies, or fetal death. The additional need for zinc during pregnancy can be met by an increase in zinc intake. An increase in zinc supplements, when excessive, can cause a decrease in copper. Therefore, it is important to determine the zinc and copper concentrations in embryonic tissue in experimental models and their relationship with embryo number and viability. BALB/c mice were divided into groups according to zinc oral supplementation and gestational age. Phagocytosis was assesed in peritoneal macrophages from dams. The zinc and copper concentrations were obtained by inductively coupled plasma-optical emission spectrometry. Zn and Cu data concentrations in all the analyzed samples were above the detection limits. No spectral interferences were found in both elements (standard reference material was used). Zinc concentrations show a tendency to increase in embryos (14 gestational days and 21 gestational days) supplemented with zinc. Copper concentrations showed a noticeable tendency to diminish (36% and 27%, respectively) in the same period. In contrast, in placenta Zn values were increased by 30% and Cu values were decreased by 26%. We suggest a pivotal role of the placenta metabolism with its homeostatic mechanisms, in these findings. An important increment appeared in the +Zn embryo number (40%) relative to control (−Zn) embryos at 21 d gestational age. Embryo mortality was at 6% in +Zn embryos and at 20% in −Zn embryos. We consider these findings, both in the number and in the viability of +Zn embryos, outstanding.     

Zinc and copper in fish from natural waters and rearing ponds in Northern Italy

Zinc and copper were detected in several tissues of fresh and saltwater fish. Liver concentrations varied widely, with respect to the storage and detoxication functions of the organ. In muscular tissues the two metals are linked to aerobic metabolism being higher in the heart and lower in the white muscle. High levels of zinc were found in the female gonad, while in the brain zinc has been shown to be more constant and possibly regulated better than copper. In sea bass supplemented with artificial diets no correlation was found between the metal content in the diet and that of the tissue. In goldfish attempts using gel filtration to isolate specific metal binding proteins of low molecular weight gave negative results, the metals were mostly bound to ligands excluded from the gel.     

Estimation of serum zinc and copper in children with acute diarrhea

Diarrhea is, in reality, as much a nutritional disease as one of fluid and electrolyte loss. Children who die from diarrhea, despite good management of dehydration, are usually malnourished and often severely so. In this study, we determined the serum levels of zinc and copper before and after standard oral rehydration solution (ORS) therapy in children with acute diarrhea and correlated it with diarrheal duration and severity. One hundred ten children suffering from acute diarrhea were included. Serum zinc and copper levels of these children were estimated at the time of enrollment and after treatment with standard ORS therapy. This study shows that children suffering from acute diarrhea show a statistically significant decrease of 13.1% and 12.8% in serum zinc and copper concentrations, respectively, compared to normal. These levels further decrease by 22.6% and 22.4%, respectively, after treatment with standard ORS therapy. Our study shows that children with the lower plasma zinc and copper levels suffered with more severe and longer duration of diarrhea. Zinc and copper supplementation could be added to standard ORS therapy for the reduction in morbidity and mortality associated with acute diarrhea in children.     

Effects of different levels of dietary zinc on the gilthead,Sparus aurata during the growing season

Gilthead were fed three diets. Diet A was the control diet, whereas diets B and C were supplemented with 300 and 900 mg Zn/kg, respectively. Fish fed with diet C, at the end of the experiment, showed the lowest weight. Zinc concentrations presented the higher values in gills, liver, and kidney. Muscle and brain had the lower mean values and showed a tight control of zinc levels. These results reinforce the hypothesis that zinc in the CNS should be strictly controlled in order to maintain the functional role of the metal. Significant differences in tissue zinc concentrations were obtained between fish fed different amounts of zinc, the metal concentrations being higher in tissues of fish fed diet C. The tissue decrease of zinc, found at the end of the experiment, may depend on a lower feed consumption or on different zinc requirements during the cold season. These changes, even if not univocal among the three diets, may be associated with the life cycle of fish. Furthermore, copper concentrations were little affected by the different concentrations of zinc in the three diets; liver and kidney presented the highest concentrations; liver showed a significant decrease in copper content at the end of the experiment. We conclude that: zinc concentrations of the diet may affect the gilthead weights and the tissual metal content; and zinc concentrations in the diets, depending on the growth rate, may be varied depending on the season.     

Quantification of toxic and inhibitory impact of copper and zinc on mixed cultures of sulfate-reducing bacteria

The adverse effects of copper and zinc on an acetate-utilizing mixed cultures of sulfate-reducing bacteria (SRB) at concentrations below the toxic concentration (minimum metal concentration at which no sulfate reduction is observed) are reported in this paper. Mathematical models were developed to incorporate the toxic and inhibitory effects (defined as the reduction in bacterial population upon exposure to the metal and the decrease in the metabolic rate of sulfate reduction by the SRB, respectively) into the sulfate-reduction biokinetics. The characteristic toxicity and inhibition constants were obtained from the measurements of bacterial populations and dissolved metal concentrations in serum bottle studies conducted at 35 degrees C and pH 6.6. Both copper and zinc had toxic and inhibitory effects on SRB. The toxicity constants for copper and zinc were 10.6 and 2.9 mM(-1), respectively, indicating that exposure to copper resulted in a higher mortality of SRB than did exposure to zinc. The values of the inhibition constants were found to be 17.9 +/- 2.5 and 25.2 +/- 1.0 mM(-1) for copper and zinc, respectively. This implies that dissolved zinc was slightly more inhibitory to SRB than copper. The models presented in the paper can be used to predict the response of a sulfate-reduction bioreactor to heavy metals during acid mine drainage treatment.     

Zinc, copper and iron concentrations in cerebral cortex of male rats exposed to formaldehyde inhalation

Retrospective cohort studies and clinical findings have suggested effects of formaldehyde exposure on the central nervous system in anatomists, embalmers and pathologists. On the other hand, harmful effects of formaldehyde inhalation on the nervous system are not well documented. The concentrations of elements such as zinc, copper and iron within the cerebral cortex indicate whether physiological conditions are maintained. In this study, adult male albino Wistar rats were exposed to formaldehyde at different concentrations (0; 6.1; 12.2 mg x m(-3)) and during different periods of time (subacute-subchronic), and body weights were recorded weekly. Zinc, copper and iron concentrations were measured in the parietal cortex using atomic absorption spectrometry after wet ashing. We conclude that subacute or subchronic exposure to formaldehyde may cause growth retardation and alter zinc, copper and iron levels in the cerebral cortex.     

Hair zinc and copper: Relationship to hair type and serum concentrations in children and adolescents

The zinc and copper serum and hair concentrations of 691 3-18-y-old girls and boys previously determined as a part of the Multicentre Study of Atherosclerosis Precursors in Finnish Children and Adolescents were further analyzed in order to find a possible association between these two zinc and copper indices. The influence of hair color and the diameter of individual hair strands on hair concentrations were studied by the analysis of covariance. Hair color and serum zinc concentrations were found to be associated with hair zinc concentrations in boys. Such an association was not found for zinc and copper concentrations in girls. Hair vs serum concentrations in different age and hair color groups did not show however, a significant relationship either in copper or in zinc concentrations. The subjects with very low or high serum zinc or copper concentrations did not usually have extreme hair concentrations and vice versa. However, there were some subjects with low or high serum concentrations associated with low or high hair concentrations.     

Chronological changes in tissue copper, zinc and iron in the toxic milk mouse and effects of copper loading

The toxic milk (tx) mouse is a rodent model for Wilson disease, an inherited disorder of copper overload. Here we assessed the effect of copper accumulation in the tx mouse on zinc and iron metabolism. Copper, zinc and iron concentrations were determined in the liver, kidney, spleen and brain of control and copper-loaded animals by atomic absorption spectroscopy. Copper concentration increased dramatically in the liver, and was also significantly higher in the spleen, kidney and brain of control tx mice in the first few months of life compared with normal DL mice. Hepatic zinc was increased with age in the tx mouse, but zinc concentrations in the other organs were normal. Liver and kidney iron concentrations were significantly lower at birth in tx mice, but increased quickly to be comparable with control mice by 2 months of age. Iron concentration in the spleen was significantly higher in tx mice, but was lower in 5 day old tx pups. Copper-loading studies showed that normal DL mice ingesting 300 mg/l copper in their diet for 3 months maintained normal liver, kidney and brain copper, zinc and iron levels. Copper-loading of tx mice did not increase the already high liver copper concentrations, but spleen and brain copper concentrations were increased. Despite a significant elevation of copper in the brain of the copper-loaded tx mice no behavioural changes were observed. The livers of copper-loaded tx mice had a lower zinc concentration than control tx mice, whilst the kidney had double the concentration of iron suggesting that there was increased erythrocyte hemolysis in the copper-loaded mutants.     

Copper and zinc metabolism with solid tumor growth

The variation in copper and zinc metabolism with tumor growth appears to relate directly to progression or regression of the disease. Historically, elevations in serum copper have been used as clinical indicators in hematological neoplasms since the early 1960s. More recently, we have monitored breast, colo-rectal, and lung cancer patients for a six-month period through courses of cytotoxic chemotherapy to determine copper and zinc changes with tumor growth. Groups were divided into responders and nonresponders blind to their serum copper and zinc levels. Trends in elevated serum copper with active disease have shown similar trends in decreasing values with effective therapy, but normalization was at a slower rate. Serum zinc levels in the same patients were markedly below normal and did not increase in the study period. The clinical significance or elevated serum copper and depressed serum zinc is discussed and the potential relationship between the two elements is explored. A solid tumor-bearing rat model, mammary adenocarcinoma R 3230 AC, has detailed more of the changes in copper and zinc metabolism with solid tumor growth. Serum copper and zinc varied with tumor mass, as in clinical studies. Liver values of the two essential metals did not change significantly, but liver-related copper-containing enzymes showed marked variations. Ceruloplasmin in serum increased with increasing tumor mass, as would be expected with the increased serum copper levels. Cytochrome c oxidase activity in liver homogenates from tumor-bearing animals was significantly depressed.     

The effect of aging on the mineral status of female mice

To clarify the effect of aging on the mineral status of female mice, mineral concentrations in their tissues were determined. Five 2-mo-old, five 6-mo-old, and five 10-mo-old female B10BR mice were fed a commercial diet. Iron, zinc, copper, calcium, magnesium, sodium, and potassium concentrations in the blood, liver, kidney, heart, brain, lung, and spleen of the mice were determined using a flame atomic absorption spectrophotometer. Iron concentrations in the liver, kidney, heart, brain, and spleen increased with age. Significant differences were detected between mice 2 and 6 mo of age and between mice 2 and 10 mo of age. Zinc concentrations in the heart and lung decreased significantly with age. Zinc concentrations in the heart and lung of 10-mo-old mice were significantly lower than those of 2-mo-old mice. It is noteworthy that the copper concentration in the brain of 10-mo-old mice was markedly higher compared with that of younger mice. Calcium accumulation was apparent in the kidney of mice at 10 mo.     

Relative and combined effects of ethanol and protein deficiency on some hair trace elements

This study was performed in order to analyze the relative and combined effects of ethanol and protein deficiency on hair copper, zinc, manganese, and iron content in four groups of seven animals each which were pair-fed during 8 wk with (1) a nutritionally adequate diet, (2) a 36% (as energy) ethanol-containing isocaloric diet, (3) a 2% protein, isocaloric diet, and (4) a 36% ethanol, 2% protein isocaloric diet, respectively, following the Lieber-DeCarli model, and to analyze the relationship between hair copper, zinc, manganese, and iron content, and the liver and muscle content of these elements. Although there was a trend to higher levels of all the elements analyzed in the the hair of the low-protein fed animals, differences were statistically significant regarding copper and manganese, effects being solely attributable to the low protein diet, not to ethanol. Moreover, hair copper was significantly, inversely related with final weight and weight loss. There were significant relationship between liver zinc and muscle zinc (r=0.57, p=0.002), but not between liver or muscle zinc and hair zinc; no correlations were observed between muscle copper and hair copper, nor between liver manganese and hair manganese. An inverse, statistically significant correlation was observed between liver copper and hair copper (r=−0.39, p<0.05).     

Metabolism of copper and zinc in the liver and bone of the perinatal guinea-pig

Hepatic copper concentration in the guinea-pig increased markedly during the second-half of gestation, attaining a maximum shortly after birth; thereafter, concentration declined rapidly during the neonatal period. Changes in perinatal hepatic copper concentrations paralleled the binding of copper to a cytosolic metallothionein-like component, and the loss of hepatic copper in the neonates coincided with increases in serum copper concentrations. Zinc concentrations of the perinatal liver were low and showed no dramatic developmental changes. The humerus showed striking increases in zinc concentration with gestational age, attaining peak concentration before term and a marked depletion of tissue zinc during the neonatal period.     

Metabolism of zinc and copper in the neonate: Zinc thionein in developing rat brain,heart, lung,spleen, and thymus

In a continuing study of the importance of metallothionein (MT) in the growth and development of neonates, zinc and copper metabolism in rat brain, heart, lung, spleen, and thymus has been analyzed in 5, 10, 15, 20 and 25 day old rats. Total, cytosol, and MT zinc and copper concentrations and organ contents were determined. Zinc, but very little, if any copper was associated with MT in these organs. Concentrations ranged from 0.03 to 3.3 μg Zn in MT/g; organ contents ranged from 0.003 to 2.2 μg Zn in MT/organ. Brain exhibited the highest concentrations and contents of zinc in MT, approaching the levels found in kidneys. Rank order of organ contents of zinc in MT was brain > lung > heart, spleen, thymus, during this neonatal growth period. When organ growth was rapid, a large percentage (20–95%) of the cytosolic zinc present in these organs was associated with MT, as has been previously observed with liver, kidneys, and testes. None of these organs undergoes the dramatic changes in zinc and copper metabolism previously observed in neonatal rat liver and gastrointestinal tract, and in maturing testes. They are more comparable to kidneys in their concentrations of zinc in MT. Like testes, little copper is found in these organs.     

Meat diets and fragile bones: Inferences about osteoporosis

Because women supplemented with copper have improved bone density and femurs of rats deficient in copper have decreased mechanical strength, the hypothesis that mice fed meat would have fragile bones was tested. Mice fed sirloin are hypercholesterolemic in comparison to mice fed meat and beef liver because of a relative deficiency of copper compared to zinc. Male, albino, Swiss mice were fed trimmed sirloin or sirloin supplemented with beef liver (3/1 by weight). After 62 days, when hypercholesterolemia was detected, mice were killed and femurs were removed, cleaned and dried. Breaking strength was measured carefully at room temperature. The meat diet produced femurs 23% weaker (8.8 +/- 0.70 N/mg.100 vs 11.4 +/- 0.92, mean +/- SE, p < 0.04) in comparison to meat plus liver. Calcium, copper and phosphorus concentrations were unaffected but zinc was mildly elevated in the weak bones (426 +/- 17.5 pg/g vs 355 +/- 9.23, p < 0.002). These elements generally are unaltered in osteoporotic bones. Because copper deficiency produces osteoporosis in animals and people and because the Western diet often is low in copper, further tests of the hypothesis that diets low in copper contribute to osteoporosis are warranted.     

Kinetics properties of Cu,Zn-superoxide dismutase as a function of metal content

The kinetics of bovine Cu,Zn superoxide dismutase were studied by pulse radiolysis. To ensure the absence of catalytically active free copper, commercially obtained holo-superoxide dismutase was demetallated, and the apo-superoxide dismutase concentrations were determined by isothermal titration calorimetry prior to reconstitution with defined amounts of copper and zinc. The catalytic rate constant was determined as a function of ionic strength over the range of 4-154 mM, and of the copper and zinc content. The catalytic rate constant increases with ionic strength up to (1.5 +/- 0.2) x 10(9) M(-1) s(-1) at an ionic strength of 15 mM, and then decreases. At pH 7 and 50 mM ionic strength, k = (1.2 +/- 0.2) x 10(9) M(-1) s(-1), and at a physiologically relevant ionic strength of 150 mM, it is (0.7 +/- 0.1) x 10 (9) M(-1) s(-1). The effect of ionic strength is ascribed to the inhomogeneous electric field generated by the surface charges of superoxide dismutase. The value of the catalytic rate constant at 50 mM is ca. 2-fold smaller than earlier values reported in the literature. The relationship between copper content and the catalytic rate constant shows that addition of more than a stoichiometric amount of copper cannot be masked efficiently by EDTA. The possibility exists that earlier reported values were based on experiments contaminated with trace amounts of copper.