Age-dependent changes in metallothionein levels in liver and kidney of the Japanese

Samples of liver, renal cortex, and medulla were obtained from 55 forensic autopsies (0- to 95-yr-old Japanese). Metallothionein (MT) was determined by the Ag-hem or Cd-hem method. Zinc (Zn), copper (Cu), and cadmium (Cd) were determined by atomic absorption spectrophotometry. The mean levels of MT were 250 μg/g in the liver, and 394 μg/g (cortex) and 191 μg/g (medulla) in the kidney. Age-dependent changes were observed in both the liver and kidney. In the liver, MT level decreased during infancy and increased thereafter with age. Similar age-dependent changes in the levels of Zn and Cu were observed. In the kidney cortex, MT level increased with age, although no correlation was found after middle age. The levels of Cd and Zn also increased with age until middle age; however, they decreased thereafter. These results suggest that age-dependent changes in renal MT levels are associated with accumulation of Cd.     

Changes in trace element concentrations in hair of growing children

Head hair concentrations of zinc, copper, manganese, and iron from a total of 418 subjects (154 male and 264 female) aged between 6 mo and 20 yr were measured mainly with flameless atomic absorption spectrophotometry. Only zinc analysis of a part of the female samples (n=140) were analyzed with inductively coupled plasma-atomic emission spectrometry. The two analytical methods showed close agreement. The mean concentration of copper and manganese were significantly higher in male subjects than in female subjects. The trace element concentrations in hair varied with the subject’s age. Zinc concentration in hair decreased from 6 mo to 14 yr in the male subjects and decreased from 6 mo to 12 yr in the female subjects. Then, the concentrations increased gradually to 20 yr in the both sexes. Age-dependent variations of copper and manganese concentrations in hair showed similar trends to those of zinc. The results of this study suggest that a higher concentration in the diet of these trace elements may be required for growing children, especially in the period of adolescence.     

Plasma zinc and copper in Paris area preschool children with growth impairment

Plasma zinc, copper, and parameters of growth were measured in a group of 116 French preschool children, 2–5 yr-old from low-income households. Participants were selected on the basis of Z-scores of weight for height (WHZ) and height for age (HAZ). Zinc and copper concentrations of children with growth impairment (GI), defined by a WHZ and/or HAZ< −1 Z-score, were compared to those of age, sex, and ethnic origin matched controls (WHZ and HAZ >−1 Z-score). Mean (±SD) plasma zinc concentration was 12.58±1.84 μmol/L in the GI group, and 13.27±1.98 μmol/L in the controls. The difference of the means of paired samples was 0.69±2.34, and by pairedt-test the significance reachedp=0.028. This effect was primarily a result of the weight retarded group (WHZ <−1 Z-score,p<0.009) and to the girls (p<0.05). There were no significant differences in plasma copper concentrations between groups. These results suggest the presence of marginal zinc deficiency in French preschool children with low weight for height Z-scores.     

Urinary cadmium levels during pregnancy and postpartum

It is well established that pregnancy induces physiological, metabolical and hormonal changes. As a consequence, trace metal metabolism can be affected. The aim of the present study was to assess the urinary cadmium levels in women during gestation and postpartum. The survey was conducted in a group of nonoccupationally cadmium-exposed women from Southern Catalonia (NE, Spain). Urine samples were obtained before pregnancy, during the 6th, 10th, 26th, and 30th wk of gestation, as well as during the 5th and 24th wk after delivery. Urinary cadmium levels were determined by graphite furnace atomic absorption spectrophotometry. The concentrations of zinc and copper in plasma were also measured. Moreover, to assess the effect of the diet during pregnancy, dietary ingestions of zinc, iron, and calcium were also determined. A significant decrease of plasma zinc levels could be observed during the last two trimesters of pregnancy, while plasma copper concentrations significantly increased during the same period. Urinary cadmium concentrations ranged from 0.05 to 3.79 μg/g creatinine (geometric mean 0.49±2.26 μg/g creatinine). No significant changes in urinary cadmium concentrations during pregnancy and postpartum could be observed.     

A hydrogen-peroxide digestion system for tissue trace-metal analysis

Tissue digestion prior to analysis for trace metals is usually carried out with strong acids. Nitric acid, alone or in combination with perchloric acid, is most commonly used. In addition to the laborious acid washing of all glassware prior to use, the digestion necessitates exposure to potential environmental contamination. Use of perchloric acid mandates a specially constructed hood with facilities for washing to remove acid deposits. A simple digestion procedure using 30% hydrogen peroxide in polyethylene vials in an oven at approximately 75°C has been previously described for the measurement of zinc in tissues using flame or flameless atomic absorption spectrophotometry and of selenium in liver by flameless atomic absorption. Readings for reagent blanks were insignificant. The technique has been further developed with a reduction in digestion time using 50% H₂O₂. Analysis of liver has been extended to include copper, manganese, and arsenic. Although the level of arsenic present was too low to be detected, 50 and 100 ng of this element added to the liver powder was completely recovered. The digest obtained when dissolved in appropriate solvent is suitable for analysis for multiple trace metals. Author to whom all correspondence and reprint requests should be addressed.     

Determination of urinary zinc,chromium, and copper in steel production workers

The aim of our investigation was to determine the concentrations of Cu, Zn, and Cr in urine samples under routine clinical laboratory conditions. To asses the reliability of these methods, critical factors such as detection limit(s), calibration range(s), cost, accuracy, and precision were studied. Our method was employed for the quantitative determination of zinc, chromium, and copper in urine samples from steel production and quality control (QC) workers and healthy unexposed controls. After pretreatment with acids, the samples were digested via a microwave oven. Zinc was determined by flame absorption spectrophotometry (FAAS), whereas chromium and copper were determined by a graphite-furnace atomic absorption spectrophotometry (GFAAS). Our results indicate that urinary zinc, chromium, and copper levels of the exposed workers are significantly higher than those of the controls. The possibility that these metals are involved in the etiology of diseases is discussed and recommendations are made to improve workplace ventilation and industrial hygiene practices.     

Significance of serum trace element status in patients with rheumatic heart disease

It is known that certain trace elements can affect various heart diseases. In this study, we aimed to evaluate the changes in concentrations of certain serum trace elements in patients with chronic rheumatic heart disease (RHD). Serum analysis of selenium (Se), zinc (Zn), and copper (Cu) trace elements was assayed by atomic absorption spectrophotometry. RHD patients had significantly lower serum concentrations of Se and Zn than control subjects (p<0.05 and p<0.001, respectively). However, the serum Cu concentration was significantly higher in RHD patients than in controls (1.93±0.59 μg/L vs 1.06±0.29 μg/L; p<0.001). Similarly, the Cu/Zn ratio in RHD patients was higher than in control subjects (4.70±0.92 vs 1.68±0.45; p<0.001). Additionally, no significant correlation was found among these trace element concentrations and the functional capacity classes (p>0.05). RHD patients had decreased serum Se and Zn element concentrations and increased serum Cu element concentration. We suggest that Se and Zn deficiency might be contributory factors in the development of rheumatic heart disease, and a high Cu concentration and a high Cu/Zn ratio might reflect an ongoing inflammatory process in this disease.     

Regional distribution of metallothionein, zinc, and copper in the brain of different strains of rats

The regional brain distribution of metallothionein (MT), zinc, and copper in the brain was determined in nine anatomical regions (olfactory bulb, cortex, corpus striatum, hippocampus, thalamus plus hypothalamus, pons plus medulla oblongata, cerebellum, midbrain, and white matter) and was compared between two different strains of rat (Sprague-Dawley [SD] and Lewis). No significant difference was observed in the whole-brain MT level between the two strains (17.8 ± 3.4 μg/g in SD rats and 20.3 ± 2.3 μg/g in Lewis rats). In SD rats, however, MT was more highly expressed in the white matter than in the other regions studied. In contrast, MT concentration was highest in the cortex and lowest in the olfactory bulb in Lewis rats. The MT levels in the cortex, corpus striatum, hippocampus, and thalamus plus hypothalamus were significantly lower in SD rats than in Lewis rats. In both strains, the olfactory bulb contained markedly higher levels of both zinc and copper than the other regions (27.9 ±6.8 μg/g zinc in SD rats and 27.6 ± 6.9 μg/g zinc in Lewis rats, and 5.2 ± 1.5 μg/g copper in SD rats and 11.1 ± 4.8 μg/g copper in Lewis rats). The next high-est zinc levels were seen in the hippocampus, whereas the next highest copper levels were in the corpus striatum in both SD and Lewis rats. The high levels of zinc and copper in the olfactory bulb were not accompanied by concomitant high MT concentrations. These results indicate that the strain of rat as well as the anatomical brain region should be taken into account in MT and metal distribution studies. However, the highest concentrations of zinc and copper in olfactory bulb were common to both SD and Lewis rats. The discrepancy between MT and the metal levels in olfactory bulb suggests a role for other proteins in addition to MT in the homeostatic control of zinc and copper.     

The changes of metabolism balance of zinc and copper in gastric juice with widely varying dietary zinc intake

The concentrations of zinc and copper in gastric juice of humans who had widely varying dietary zinc intake were evaluated. In order to compare this with zinc and copper levels of normal dietary individuals, we also determined the zinc and copper levels in healthy individuals' plasma and in cancer patient's natural tissue, all of whom had normal diets. The correlation coefficients between zinc and copper were 0.71, 0.45, and 0.55, respectively, in gastric juice, plasma, and tissue of normal dietary subjects. Such correlation changed and was destroyed when there was a high zinc level in gastric juice. When gastric juice zinc level changed from mean value 16.8 μmol/L to 262.5 μmol/L, the correlation coefficient varied from 0.71 to −0.04, and the copper level also varied from mean value 8.96 μmol/L to 4.89 μmol/L. These findings probably give the evidence to suggest that a high zinc level will restrain the copper level and break the balance of the human body's zinc and copper metabolism.     

Effects of trichophytosis on serum zinc levels in calves

The purpose of this study was to determine the zinc levels in calves with trichophytosis and to research the importance of zinc for fungi. The sera of 20 calves with trichophytosis and 10 healthy calves were used in this study. Zinc levels of the sera were measured by the atomic absorption spectrophotometer method. Serum zinc levels of diseased and healthy animals were found to be 42.0±16.6 μg/dL and 75.8±5.9 μg/dL, respectively. Serum zinc levels of diseased calves were lower than healthy ones and this difference were found to be important statistically (p<0.001), whereas there is no statistical difference on the levels of lymphocyte, monocyte, granulocyte, erythrocyte, hemoglobin, hematocrit, and mean corpuscular volume between groups. These parameters were not influenced by low zinc levels.     

Heavy metal composition of polysomal fractions following cadmium challenge

Endogeneous levels of zinc and copper were found to be 1.2±0.1×10⁻² and 0.3±0.1×10⁻² μg/A260 unit, respectively, in polysomal fractions from control animals; cadmium, however, was undetectable. In experimental animals (injected with cadmium) zinc, copper, and cadmium were found in polysomal fractions isolated by two different methods. One hour after a cadmium injection there was a rise in both the zinc and copper content of the polysomal fractions, which then declined steadily to below control levels by 16 h. Neither zinc nor cadmium were dialyzable from these fractions by a TRIS buffer; however, addition of 0.01M EDTA to the buffer resulted in removal of 75% of the zinc and all of the detectable cadmium. The addition of cadmium (CdCl₂) to control supernatants (adjusted to the cadmium concentration present in supernatants 6 h after in vivo exposure) resulted in metal binding to polysomal fractions in levels comparable to those observed after in vivo exposures to the metal. When cadmium was added in the form of cadmium thionein, a smaller fraction of the metal was isolated with the polysomal fraction. Cadmium bound to polysomal fractions in vivo (24 h after exposure) was sensitive to release by protease digestion, but insensitive to release by ribonuclease digestion.     

Zinc and copper in Indian patients of tuberculosis

The effectiveness and success of antitubercular therapy is mainly measured by identifying the organism in sputum. In certain patients, especially in geriatric patients, available tuberculosis tests are not satisfactory and do not provide enough information on the effectiveness of antitubercular therapy, as the symptoms might be confused with the existing symptoms of ongoing diseases. Therefore, 60 diagnosed and randomly selected patients with tuberculosis were included into this study. The patients with other associated diseases likely to influence serum copper and zinc were not included in the study. The estimations of serum copper and zinc were done in healthy volunteers and in tubercular patients before the start of treatment and after 4 wk of antitubercular treatment. The average plasma concentration of serum copper and zinc in healthy volunteers were 102±20 μg/dL and 96±18 μg/dL respectively. In tuberculosis patients, serum copper and zinc levels were 123.65±9.98 μg/dL and 64.14±3.97 μg/dL, respectively, before the start of treatment, which came down to 116.23±4.27 μg/dL and 74.31±3.60 μg/dL, respectively, after 4 wk of antitubercular treatment.     

Chromium in a series of Portuguese plants used in the herbal treatment of diabetes

Chromium (Cr³⁺) is an essential micronutrient for humans. Its main action is thought to be the regulation of blood sugar, because chromium deficiency is associated with diabetic-like symptoms, and chromium supplementation is correlated with increased glucose tolerance and insulin sensivity. Some Portuguese aromatic plants are utilized as tisanes by diabetic people as medicinal plants. Their active principle is not yet known, and the importance of their chromium content in the claimed therapeutic properties should not be discarded. Therefore, determination of chromium in some Portuguese medicinal plants was performed by flameless atomic absorption. All the analyzed plants contain chromium at the normal level for this element, but the plants used to prepare tisanes to help diabetic conditions contain higher levels (2.2 μg/g dry wt ±0.88;n=11) than the others (0.88 μg/g dry wt±0.18;n=17).     

Expression of the Zinc Transporters Genes and Metallothionein in Obese Women

Research has investigated the participation of zinc transport proteins and metallothionein in the metabolism of this mineral. However, studies about the genetic expression of these proteins in obese patients are scarce. The study determined the expression of zinc transporter protein codifying genes (ZnT-1, Zip-1 and Zip-3) and of metallothionein in 55 obese women, aged between 20 and 56 years. The assessment of body composition was carried out using anthropometric measurements and bioelectrical impedance. Zinc intake was obtained by recording diet over a 3-day period, and the nutritional analysis was carried out using NutWin software version 1.5. The plasmatic and erythrocytary zinc were analyzed by atomic absorption spectrophotometry (λ = 213. 9 nm). The determination of mRNA expression of the zinc transporter proteins and metallothionein was carried out using blood, using the RT-PCR method. The mean values of body mass index were 37.9 ± 5.5 kg/m². The average intake of zinc was 9.4 ± 2.3 mg/day. The analysis of the zinc plasma concentrations showed values of 58.4 ± 10.9 μg/dL. The mean values of zinc in the erythroytes were 38.7 ± 9.1 μg/g Hb. The metallothionein gene had a higher expression in the blood, when compared to zinc transporters ZnT-1, Zip-1, and Zip-3 (p = 0.01). The study shows that there are alterations in the biochemical parameters of zinc in obese patients assessed, as well as higher expression of the codifying gene metallothionein, when compared to the investigated zinc transporters.     

Determination of the major zinc fractions in human serum by ultrafiltration

In this paper we report a method for measuring ultrafiltrable zinc in human serum by electrothermal atomic absorption spectrophtometry. We show also that ultrafiltration permits to determine alpha-2 macroglobulin bound zinc and losely bound zinc if a strong zinc ligand (EDTA) is added to serum before ultrafiltration. This last fraction, after deduction of ultrafiltrable zinc, represents roughly all albumin bound zinc. In 20 controls we found that ultrafiltrable zinc amounted 0.311 μmol/L (S.D.=0.117 μmol/L), alpha-2 macroglobulin bound zinc 3.08 μmol/L (S.D.=0.221 μmol/L), and albumin bound zinc 12.11 μmol/L (S.D.=1.95 μmol/L). Our method needs only a small volume of serum, it is simple and rapid but also very accurate and reliable. The losely bound fraction is very dynamic and, representing the physiologically active part of serum zinc, it could be a good marker of zinc deficiency.     

Zinc,copper, selenium,and glutathione peroxidase in blood of 11-yr-old dunedin,New Zealand children

Blood was obtained from 564 11-yr-old children who had participated since birth in a multidisciplinary health and development study. Serum zinc concentration did not differ between the boys and the girls (mean±SD: 91=17 μg/100 mL,n=453). Five-6% of serum zinc values were low; although there was a weak correlation with height, none of the boys with low values were below the 10th percentile for height for this group. Serum copper concentration (112±24 μg/100 mL,n=454) was unrelated to sex, height, weight, body mass index, socioeconomic status (SES), or iron status. Blood selenium concentration (49±10 ng/mL,n=564) was lower than previously reported for Dunedin children; it was higher in children in the lower SES categories. The data represent normal values for healthy, 11-yr-old NZ children.     

Effects of cadmium and copper on zinc transport kinetics by isolated renal proximal cells

Zinc, cadmium, and copper are known to interact in many transport processes, but the mechanism of inhibition is widely debated, being either competitive or noncompetitive according to the experimental model employed. We investigated the mechanisms of inhibition of zinc transport by cadmium and copper using renal proximal cells isolated from rabbit kidney. Initial rates of⁶⁵Zn uptake were assessed after 0.5 min of incubation. The kinetics parameters of zinc uptake obtained at 20°C were a J_max of 208.0±8.4 pmol· min⁻¹·(mg protein)⁻¹, aK _m of 15.0±1.5 μM and an unsaturable constant of 0.259±0.104 (n=8). Cadmium at 15 μM competitively inhibited zinc uptake. In the presence of 50 μM cadmium, or copper at both 15 and 50 μM, there was evidence of noncompetitive inhibition. These data suggest that zinc and cadmium enter renal proximal cells via a common, saturable, carrier-mediated process. The mechanisms of the noncompetitive inhibition observed at higher concentrations of cadmium or with copper require further investigation, but may involve a toxic effect on the cytoskeleton.     

Concentations of copper, Zinc, and magnesium in sera from patients with idiopathic dilated cardiomyopathy

Trace elements are known to have a key role in myocardial metabolism. The accumulation (cobalt, arsenic, copper) or deficiency (selenium, zinc) of trace elements may be responsible for idiopathic dilated cardiomyopathy. We investigated the trace element concentrations (Cu, Zn, Mg) in sera from patients with dilated cardiomyopathy by atomic absorption spectrophotometry. We observed that patients with dilated cardiomyopathies have higher copper and lower zinc concentrations in serum than healthy controls. The magnesium concentrations of patients did not differ significantly from that of control subjects.     

Zinc and Copper Concentrations in Human Preterm Milk

Zinc and copper are important trace elements in the nutrition of preterm infants. This study determined and compared the concentrations of zinc and copper in preterm milk of mothers receiving and not receiving zinc supplementation diets. The effects of maternal supplementation on the blood levels and anthropometric parameters were evaluated. Thirty-eight mothers and their preterm infants were enrolled in the study. Eighteen mothers were given a daily supplementation of 50 mg zinc, whereas the other 20 were not. Zinc and copper levels in milk were determined at 15-day intervals, as were blood zinc levels along with anthropometric parameters. Zinc and copper contents were determined by atomic absorption spectrophotometry. No significant differences were found between groups either for zinc values in maternal milk and infant blood or for anthropometric measurements. A pronounced decrease in copper levels was observed in mothers receiving supplemental zinc. Zinc supplementation given to mothers who were breastfeeding preterm infants had no significant effect on zinc secretion in milk.     

Cadmium and zinc content of fish from an industrially contaminated lake

Eleven species of fish from an industrially-contaminated lake were analysed for whole body cadmium and zinc content by atomic absorption spectrophotometry. Cadmium and zinc content of fish were species related, and most species accumulated these trace metals to levels significantly higher than background. Maximum concentrations detected were 13.60 μg Cd g⁻¹ (dry wt) in a bluegill and 820 μg Zn g⁻¹ in a redear sunfish. Cadmium content was much more variable than zinc content. Distributions of concentrations of both cadmium and zinc in fish were lognormal, and concentrations of both metals tended to decrease in higher trophic levels. Zinc concentrations significantly decreased as total length increased in three species.