Effects of iron,copper, zinc,calcium, and magnesium on human lymphocytes in culture

The effects of simultaneous changes of calcium, magnesium, iron, copper, and zinc concentrations were evaluated in normal human T and B lymphocytes, cultured in cation-depleted media. Optimal concentrations for thymidine incorporation (TI) in both cell populations were Fe and Zn 15 μM and Cu 5 μM; for t cells Ca 2 mM and Mg 4 mM; for B cells Ca 4 mM and Mg 6 mM. TI decreased with increasing molarity of cations and the decrease was particularly apparent with Cu. Minimal amounts of Ca and Mg (0.5 mM) were necessary for growth, even in presence of optimal concentrations of Fe, Cu, and Zn. Fe and Cu showed synergistic stimulatory effects at low concentrations and synergistic inhibitory effects at high concentrations. Antagonism between Fe and Zn, Cu and Zn, and Ca and Zn was also demonstrated. CD4/CD8 increased with PHA stimulation in presence of Zn, and decreased with ConA stimulation in presence of Zn or Fe. The results demonstrate: (1) the relationship and interdependence of Fe, Cu, and Zn concentrations in modulating the growth of normal lymphocytes; (2) the stimulatory effects of Fe on B cells and Zn on CD8 positive cells; (3) the inhibitory effect of Cu at concentrations lower than those of Fe and Zn; (4) the requirement of Ca and Mg in certain concentration and ratio for the action of the other cations; and (5) the Ca and Mg requirement for the growth of B cells higher than T cells.     

Determining zinc with commonly used calcium and zinc fluorescent indicators, a question on calcium signals

Investigations into the roles of Ca(2+) and Zn(2+) in cell biology have been facilitated by the development of sensitive fluorometric probes that have enabled the measurement of Ca(2+) or Zn(2+) in both extracellular and intracellular environments. It is critical to be aware of the specificity and relative selectivity of a probe for the targeted ion. Here, we investigated metal-ion responses by screening nominally Zn(2+)- or Ca(2+)-selective fluorophores in solutions containing various concentrations of Ca(2+), as a potential interferent for Zn(2+), or Zn(2+), as a potential interferent for Ca(2+). The results suggested that Zn(2+)-sensitive dyes were more specific for their targeted ion than dyes that targeted Ca(2+). Ca(2+)-sensitive dyes such as Calcium Green-1, Fura-2, and Fluo-3 showed a wide range of interaction with Zn(2+), even responding to Zn(2+) in the presence of high concentrations of Ca(2+). We demonstrate that these Ca(2+) indicators can effectively measure dynamic changes of cytosolic Zn(2+). Our results appeal for a new generation of Ca(2+) fluorophores that are more specific for Ca(2+) over Zn(2+). One implication of these results is that data obtained using Ca(2+)-sensitive dyes may need to be re-examined to determine if results previously attributed to Ca(2+) could, in part, be due to Zn(2+).     

Effects of iron,zinc, calcium,and vitamins on the activity and contents of human placental copper/zinc and manganese superoxide dismutases

One hundred seventy-nine pregnant women, ages 15–45 yr, were divided into three groups. Group A was orally given one spansule per day containing 150 mg dried ferrous sulfate, 61.8 mg zinc sulfate, and 500 μg folic acid, starting from the first 4 wk of pregnancy and ending at the day of delivery. Similarly, group B was given one tablet containing 625 mg calcium carbonate, 1000 mg vitamin C, 300 IU Vitamin D, 1350 mg citric acid, and 15 mg Vitamin B6. Group C was without any supplements and served as a control. Mothers who received iron/zinc supplements (group A) during pregnancy had significantly higher copper/zinc superoxide dismutase activity in their placentae than calcium/vitamin-supplemented mothers (group B) or unsupplemented mothers (group C). The enzyme activity increased with age of the mothers from 15 to 40 yr, then decreased after in both supplemented groups, whereas this increase and decrease occurred at early age in the unsupplemented group. Immunochemical quantitation of the enzyme contents showed no significant difference between the supplemented and unsupplemented groups, suggesting that the observed increase in the enzyme activity might arise from posttranslational processing of the enzyme. The placental manganese superoxide dismutase activity and contents, however, were similar in the supplemented groups, whereas they were slightly higher in the unsupplemented group; the overall superoxide dismutase-like activities in the placentae were the highest in iron-zinc supplemented group and the lowest in the unsupplemented group.     

Effects of salicylate and zinc deficiency on the serum concentrations of magnesium,calcium, and parathyroid hormone

Oral application of 700 mg/kg salicylic acid to pregnant and nonpregnant female rats caused an increase of serum Mg²⁺ and a decrease of serum Ca²⁺ concentration. The salicylate effect was drastically enhanced by Zn deficiency. The increase in serum Mg²⁺ is probably caused by the nephrotoxicity of salicylate. The decrease of serum Ca²⁺ concentration is combined with an increase of parathyroid hormone concentration in serum. Probably, salicylate and Zn deficiency inhibit Ca²⁺ mobilization by parathyroid hormone in bone.     

Effects of elevated cytosolic calcium on ACh-induced swine tracheal smooth muscle contraction

Increased intracellular calcium concentration ([Ca²⁺]_i) is required for smooth muscle contraction. In tracheal and other tonic smooth muscles, contraction and elevated [Ca²⁺]_i are maintained as long as an agonist is present. To evaluate the physiological role of steady-state increases in Ca²⁺ on tension maintenance, [Ca²⁺]_i was elevated using ionomycin, a Ca²⁺ ionophore or charybdotoxin, a large-conductance calcium-activated potassium channel (K_Ca) blocker prior to or during exposure of tracheal smooth muscle strips to Ach (10^–9 to 10^–4 M). Ionomycin (5 µM) in resting muscles induced increases in [Ca²⁺]_i to 500±230 nM and small increases in force of 2.6±2.3 N/cm². This tension is only 10% of the maximal tension induced by ACh. Charybdotoxin had no effect on [Ca²⁺]_i or tension in resting muscle. After pretreatment of muscle with ionomycin, the concentration-response relationship for ACh-induced changes in tension shifted to the left (EC₅₀=0.07±0.05 µM ionomycin; 0.17±0.07 µM, control, p<0.05). When applied to the muscles during steady-state responses to submaximal concentrations of ACh, both ionomycin and charybdotoxin induced further increases in tension. The same magnitude increase in tension occurs after ionomycin and charybdotoxin treatment, even though the increase in [Ca²⁺]_i induced by charybdotoxin is much smaller than that induced by ionomycin. We conclude that the resting muscle is much less sensitive to elevation of [Ca²⁺]_i when compared to muscles stimulated with ACh. Steady-state [Ca²⁺]_i limits tension development induced by submaximal concentrations of ACh. The activity of K_Ca moderates the response of the muscle to ACh at concentrations less than 1 µM.     

Dietary zinc effects on zinc, calcium, and magnesium content in bones of growing rats

The aim of the present study was to assess dietary zinc effects on femur weight and mineral content in growing rats. For this purpose, 70 weanling Sprague-Dawley rats were divided into four groups. Each group was subject to a diet containing 2 (BZ), 5 (DZ), 10 (MZ), and 30 (CZ) ppm zinc. The calcium and magnesium content in all diets was 5 g/kg and 507 mg/kg, respectively. The animals were kept on this regime for 28 d and then sacrificed and their femurs were removed for analysis using atomic absorption spectrophotometry. The weights of the BZ and DZ groups were significantly different from the MZ and CZ groups (38.5±10.5, 89.9±13.7, 118.6±13.6 and 134±19.9 g, p<0.01) respectively. There were no differences between the MZ and CZ groups. Femur weight also varied with dietary zinc, as it was significantly different among all groups (BZ, 265±49 mg; DZ, 380±40 mg; MZ, 452±54 mg; CZ, 735±66 mg; p<0.01). The femur zinc content varied with diets, following a different pattern than the above parameters. Femur zinc from the BZ group (51.5±5.4 ppm) was significantly different from the MZ and CZ groups (115.9±14.2 and 175.0±13.5 ppm, respectively), whereas the DZ group (62.5±11.3 ppm) did not differ from the other three groups. The femur content of calcium (BZ, 83.2±9.8 mg/g; DZ, 88.0±9.2 mg/g; MZ, 90.2±13.6 mg/g; CZ, 83.1±14.7 mg/g) and magnesium (BZ, 1.82±0.13 mg/g; DZ, 1.98±0.09 mg/g; MZ, 1.93±14 mg/g; CZ, 1.83±0.19 mg/g) were not significantly different among the groups, nor was the calcium-magnesium ratio. These results suggest that although dietary zinc deficiency retards growth and causes bone fragility, bone deposition of calcium and magnesium and its ratio are not affected.     

Magnesium,calcium, copper,and zinc in meals

Meals of 12 diets were prepared from conventional foods with precautions against contamination by metallic elements because of epidemiologic associations between ischemic heart disease and the metabolism of magnesium, calcium, copper, and zinc. Magnesium, calcium, copper, and zinc were measured by atomic absorption spectrometry with satisfactory accuracy and precision. The mean daily amount of copper in the diets was less than the apparent adult requirement. Mean amounts of magnesium and zinc were close to apparent requirements; however, adults consuming amounts less than one standard deviation below these means may be depleting body stores and be at risk of pathology. Magnesium and copper were highly correlated (r=0.849,P=0.0001) in meals. This and other significant correlations probably will prevent the relationships of these elements to ischemic heart disease from being elucidated by epidemiology. Metabolic experiments will be necessary to differentiate among several hypotheses.     

Effects of combined administration of calcium,iron, zinc,chrysanthemum flavonoids,and DMSA on the treatment of lead intoxication in mice

The effect of combined administration of calcium (Ca), iron (Fe), zinc (Zn), chrysanthemum flavonoids, and meso‐2,3‐dimercaptosuccinic acid (DMSA) on the treatment of lead (Pb) intoxication in mice was studied. One hundred ninety female mice (SPF level, aged 18‐22 days) were randomly divided into two groups as experimental animals. Mice in group I (10 mice) served as normal control animals, and were administered deionized water containing 12.5 μL/L acetate acid for 6 weeks, whereas mice in group II (180 mice) were exposed to 0.1% (wt/vol) of lead acetate in deionized water for 6 weeks and served as experimental animals. After 6 weeks of successful modeling, 180 mice from group II (lead‐exposed) were divided into 18 groups of 10 mice each, 16 of which were treated by the combined administration of Ca, Fe, Zn, chrysanthemum flavonoids, and DMSA by L₁₆ (2¹⁵) orthogonal design. The remaining two groups were given treatment with low and high doses of DMSA, respectively. After three weeks of intervention (ig), the optimal treatment group was identified according to its blood lead level, as well as some antioxidant indices in the blood, liver, and hippocampus. The results indicated that the combined administration of Fe, Zn, chrysanthemum flavonoids, and DMSA with low dosage had the most significant effect on increasing the activities of blood delta‐aminolevulinic acid dehydratase and superoxide dismutase (SOD), hepatic SOD and hippocampus nitric oxide synthase while decreasing the blood lead level, the content of hepatic malondialdehyde and hippocampus nitric oxide; this was considered the optimal treatment group. There was no difference in the level of blood hemoglobin between the optimal treatment group and the model control group (the first group of the orthogonal experiment). The activities of blood glutathione (GSH), hepatic GSH and glutathione peroxidase of the optimal treatment group were the same as other groups’, and the recovery of the related indexes in the optimal effect group closely resembled the high dosage DMSA group. It can be concluded that the coadministration of Fe, Zn, and chrysanthemum flavonoids along with a low‐dose DMSA effectively reduces Pb poisoning and lead‐induced oxidative damage in lead‐exposed mice; the result may provide a theoretical reference for the treatment of Pb poisoning.     

Effects of zinc,selenium, and calcium on the nephrotoxicity of cadmium in primary cultures of rat renal proximal epithelial cells

The influence of essential metals, like zinc, selenium, and calcium, on the nephrotoxicity of cadmium was studied in primary cultures of rat proximal tubular cells. Damage to kidney cells was assessed by measuring the release of lactate dehydrogenase (LDH), γ-glutamyltranspeptidase (GTP), and β-N-acetylglucosaminidase (NAG) from cells into the medium and the cellular concentration of protein. Incubation with 200 μM cadmium in the presence of equivalent molar or lower concentrations of zinc and selenium showed greater release of LDH and NAG than cadmium alone, indicating an enhanced effect. However, metallothionein (MT) induced by pretreatment with a nontoxic concentration of zinc decreased significantly the release of enzyme from cells and elevated cellular protein levels in response to MT levels. MT provided partial protection against the nephrotoxicity of cadmium. Decreased calcium levels in the incubation medium also resulted in markedly increased release of LDH and NAG from cells exposed to cadmium and reduced cellular protein levels. These findings suggest that variations in zinc and calcium intake may affect the development of cadmium-induced renal dysfunction.     

Levels and distribution of zinc,copper, magnesium,and calcium in rats fed different levels of dietary zinc

Effects of altered dietary zinc on levels of zinc, copper, magnesium, and calcium in organ and peripheral tissues were studied. When rats fed a zinc-deficient diet (1.3 μg Zn/g) for 28 d were compared with rats fed a control diet (37.5 μg Zn/g), levels of zinc were slightly lower in plasma, hair, and skin and 50% lower in femur and pancreas, whereas the levels of copper were higher in all tissue except plasma. Magnesium levels were higher than controls in the heart and lower in the spleen, whereas the calcium levels were lower in plasma, lung, spleen, kidney, and skin and strikingly higher in brain, hair, and femur. When rats fed a zinc-supplemented diet (1.0 mg Zn/g) were compared to the same conrols, levels of zinc in these were higher in all organs and peripheral tissues studied, except heart, lung, and liver; copper levels were higher in liver, kidney, and spleen; magnesium levels were significantly higher in the spleen, but were little affected in other tissues, although calcium levels were higher in pancreas, spleen, kidney, and skin and lower in plasma and hair. These data indicate that overall copper organ and peripheral tissue levels are affected inversely, and zinc and calcium levels directly, by zinc nutriture.     

Influence of maternal dietary calcium levels on milk zinc, calcium and phosphorus contents and milk production in rats

The aim of this study was to analyze zinc (Zn), calcium (Ca) and phosphorus (P) contents in milk and the lactational performance in rats fed different Ca levels. Female Wistar rats were fed during pregnancy and lactation with experimental diets containing 20% protein and high (0.90%, HCa), normal (0.60%, NCa) or low (0.20%, LCa) Ca levels. Milk samples were collected after 15 days to determine the milk mineral composition. Pup weight was recorded from birth to weaning (litter size: 6-8 pups) to determine weight gain and calculate milk production. At delivery there were no significant differences in the body weight of the pups between the groups, but at day 15, the LCa group showed lower values than both NCa and HCa groups (p<0.05). The weight gain of the LCa group was significantly lower than of the HCa and NCa groups, between delivery and day 5 (p<0.05). This reduced rate of weight gain led to the LCa group reaching weaning weight later than the other groups. Milk production (g/pup/day) was significantly lower when dams were fed the LCa than the NCa and HCa diets (p<0.05). There were no significant differences among the groups in milk Ca, P and Zn levels and Ca/P ratio. The body mineral composition of the pups at birth did not differ between the groups; at weaning, however, both LCa and HCa groups had lower element contents than the NCa group (p<0.05). In conclusion, dams fed with a diet containing low Ca levels produced smaller volumes of milk and their pups reached weaning weights later than the other groups. As the milk mineral composition was not affected, it can be hypothesized that in dams fed low dietary Ca, the smaller milk yield might have been a way of maintaining milk quality. High Ca levels affected neither pregnancy outcome nor lactational performance.     

Effects of copper, lead and zinc on phytoplankton growth

Impact of Cu, Pb and Zn on the growth of Closterium acerosum, Pediastrum simplex, Chlorella vulgaris and Scenedesmus quadricauda was studied in vitro. At concentration 0.1 g m-3 these metals were not toxic, however, at concentration 10.0 g m-3 the growth of phytoplankton was inhibited. Cu was the most toxic followed by Pb and Zn. S. quadricauda expressed highest tolerance to these metals, and least tolerance was exhibited by C. acerosum. This revised version was published online in July 2006 with corrections to the Cover Date.     

Aspergillus niger absorbs copper and zinc from swine wastewater

Wastewater from swine confined-housing operations contains elevated levels of copper and zinc due to their abundance in feed. These metals may accumulate to phytotoxic levels in some agricultural soils of North Carolina due to land application of treated swine effluent. We evaluated fungi for their ability to remove these metals from wastewater and found Aspergillus niger best suited for this purpose. A. niger was able to grow on plates amended with copper at a level five times that inhibitory to the growth of Saccharomyes cerevisiae. We also found evidence for internal absorption as the mechanism used by A. niger to detoxify its environment of copper, a property of the fungus that has not been previously exploited for metal bioremediation. In this report, we show that A. niger is capable of removing 91% of the copper and 70% of the zinc from treated swine effluent.