Showing papers in "Biological Trace Element Research in 1985"

Regional variation of cancer mortality incidence and its relation to selenium levels in China.

Abstract: The epidemiological relationship between selenium level and age-adjusted human cancer mortality (incidence) was studied in 24 regions located in eight provinces of China. Statistically significant inverse correlation was found between age-adjusted total cancer death rates and selenium levels in whole blood from local residents. In the areas with high selenium levels, there was significantly lower mortality in both males and females from cancer of the stomach and esophagus. In addition, an inverse correlation between regional distribution of liver cancer incidence and selenium contents in blood and grains in Qidong county, an area with high risk of hepatoma, was observed. With the intention of providing selenium supplements to residents living in low selenium regions, the selenium content in grains was raised by means of foliar spraying of crops with Na2SeO3 solution.

Vitamin E and selenium supplementation in geriatric patients : A double-blind preliminary clinical trial.

Abstract: Sodium selenate (8 mg/d), organic selenium (50 μg/d) andd-alpha-tocopherol acetate (400 mg/d) were administered for 1 yr to 15 geriatric patients Fifteen comparable controls received placebo The mean age of both groups was 76 yr The patients were assessed every 2 mo independently by two nurses using the Sandoz Clinical Assessment Geriatric-scale (SCAG) The propositae, showed significant improvement in the following SCAG parameters: depression, anxiety, self-care, mental alertness, emotional lability, motivation and initiative, hostility, interest in the environment, fatigue, anorexia, and general impression A distinct improvement of the general condition was noticed after only 2 mo and the improvement continued up to the end of the 1-yr study period The high selenium and vitamin E doses were well tolerated; there were no side effects whatsoever

Zinc deficiency and the developing embryo.

Abstract: The effect ofin utero zinc deficiency on fetal development in rats is reviewed. Attention is paid to the primary biochemical lesion associated with zinc-related teratogenesis and special consideration is given to the central nervous system. Evidence is presented that the thymidine kinase salvage pathway, used for the synthesis of thymidine monophosphate in DNA synthesis, is depressed more in fetal brain tissue than in the liver. In addition, greater reliance appears to be placed on this pathway than onde novo synthesis in the fetal brain than in other tissues. Some consideration is given to the use of in vitro embryo culture in studies relating to neurogenesis, but evidence is presented of a greater capacity of explanted rat embryos to obtain zinc from maternal serum than occurs in vivo.

Tissue selenium accretion in premature and full-term human infants and children

Abstract: Development of supplementation guidelines for formulated diets and total parenteral nutrition requires knowledge of Se tissue accretion. To this end, the total organ Se content was calculated from the Se concentrations that were measured by neutron activation analysis in postmortem samples of liver (n=56), kidney (n=11), adrenal cortex (n=9), and pancreas (n=6) from infants and children from birth to 10 yr including 17 born prematurely. Hepatic Se concentrations were similar in full-term and premature newborns, decreased from birth to 1 yr, and then increased thereafter. The total hepatic Se content was significantly greater in full-term than in preterm newborns and increased with age and liver size after 1 yr. No significant differences were found between the concentrations of Se in kidney, pancreas, and adrenal tissues. Falling hepatic Se concentrations in the full-term infant concurrent with stable total organ Se content may indicate inadequate dietary intake or may reflect a normal redistribution of the nutrient. Premature infants are born with smaller stores than full-term infants and are at greater risk of developing a deficiency.

A simple method for simultaneous estimation of zinc and copper in erythrocytes : Comparison of a new methodology with a standard technique.

Abstract: A method is described for simultaneous estimation of zinc and copper in erythrocytes by hemolysis and flame aspiration atomic absorption spectrophotometry. Red blood cells (RBC) were also analyzed by the commonly used nitric acid digestion method for comparison. The difference in the results of zinc analyses of fifteen RBC samples by the two techniques was 0.5 ± 0.8 (mean ± SD) μg Zn/g hemoglobin indicating that these methods yield essentially similar results. Because of the low concentration of copper in RBC, results obtained by the acid digestion method were unreliable since nitric acid and undissolved particles of digested RBC in the acid extract increased instrumental noise to an unacceptable level. Average concentrations of zinc and copper estimated in RBC of 25 normal subjects by the present described technique (hemolysate method) were 43.9 and 2.0 μg/g Hb, respectively. No sex-related differences in RBC zinc or copper concentrations were found. The hemolysate method is simpler and faster to perform than the more commonly used nitric acid digestion method.

Effect of Dietary Copper and Zinc Levels on Tissue Copper, Zinc, and Iron in Male Rats

Abstract: The interaction between dietary copper and zinc as determined by tissue concentrations of trace elements was investigated in male Sprague-Dawley rats. Animals were fed diets in a factorial design with two levels of copper (0.5, 5 μg/g) and five levels of zinc (1, 4.5, 10, 100, 1000 μg/g) for 42 d. In rats fed the low copper diet, as dietary zinc concentration increased, the level of copper decreased in brain, testis, spleen, heart, liver, and intestine. There was no significant effect of dietary copper on tissue zinc levels. In the zinc-deficient groups, the level of iron was higher in most tissues than in tissues from controls (5 μg Cu, 100 μg Zn/g diet). In the copper-deficient groups, iron concentration was higher than control values only in the liver. These data show that dietary zinc affected tissue copper levels primarily when dietary copper was deficient, that dietary copper had no effect on tissue zinc, and that both zinc deficiency and copper deficiency affected tissue iron levels.

Zinc-binding proteins (ligands) in brains of severely zinc-deficient rats.

Abstract: Previous studies from this laboratory reported the presence of a metallothionein-like protein in brain with an apparent estimated molecular weight of 13,000-15,000 daltons. The synthesis of this protein, which incorporates large quantity of cysteine, is stimulated following administration of zinc and copper and is blocked by actinomycin D. In this study, we report that the synthesis of this metallothionein-like protein is considerably lower in brains of severely zinc-deficient rats in comparison with pair-fed orad libitum fed groups. Furthermore, incubation of partially purified metallothionein-like protein with(65)Zn and chromatography on DEAE A-25 Sephadex produced similar elution patterns in the three experimental groups. However, the extent of binding of(65)Zn to the metallothionein-like protein from the zinc-deficient rats was significantly (p<0.05) lower than the control groups. On the other hand, the total concentration of zinc in brains of zinc deficient rats did not vary from control groups. Since the synthesis of this metallothionein-like protein is reduced by zinc deficiency and is stimulated following administration of zinc, we postulate that the free pool of zinc may regulate the synthesis of its binding protein in the brain.

Serum selenium in danish Blood Bank donors.

Abstract: Serum selenium concentration was determined over a full year in healthy donors from the Blood Bank at the municipal Hospital in Aarhus, Denmark. The age range of the donors, half of whom were women, was 20–60 yr. In months with even numbers, samples were obtained from women; in months with odd numbers, from men. For estimates of individual seasonal variation, a number of the laboratory’s employees were observed with monthly samples throughout a full year.

Retention of cadmium in organs of the rat after a single dose of labeled cadmium-3-phytate

Abstract: Because of the low safety factor estimated for the normal content of Cd in human foods, it is important to establish the influence of food constituents such as phytate on the bioavailability of this toxic metal. We studied the retention of radioactive109Cd administered to rats as a chloride or a phytate in a single dose by stomach tube. The animals were fed either a normal rat chow containing 0.29% of phytate or a low phytate diet containing less than 0.1% phytate. Highly elevated levels of109Cd were found only in the animals that were supplied with109Cd as a chloride and had been fed the low phytate diet. In the animals supplied with109Cd as a phytate, which had also received the low phytate diet, the levels of109Cd in the intestine were as high as those in the group mentioned before, but the retentions in all other tissues resembled those of the respective groups fed the normal chow. The findings indicate that phytate is responsible for a considerable decrease in the intestinal absorption of Cd. Furthermore, it appears to exert an influence on the kinetics of Cd retention in the intestine.

Electron microscopical findings with special reference to cancer in rats caused by inhalation of nickel oxide.

Abstract: A special exposure system was used for the inhalation of nickel oxide (NiO) aerosol by Wistar male rats. The median aerodynamic diameter and the geometric standard deviation were 1.2 μm and 2.2, respectively. A histopathological study of the rats was performed immediately, and at intervals of 12 and 20 mo after a 1-mo expsoure to NiO. Electron microscopy showed that localization of NiO particles was restricted to the lungs and that each particle had been engulfed by the alveolar macrophages. Type II pneumocytes and nonciliated bronchiolar epithelial cells (Clara cells), as well as numerous tubular myelin (surfactant) in the alveoli were prominent. In rats dissected after 12 mo, clusters of NiO particles were still present within the terminal bronchioli, alveolar walls, and lysosomes of the alveolar macrophages. Pools of tubular myelin were observed in the peribron-chial lymphatics. The Clara cells, which project into the lumen of bronchioli, showed active secretion and were filled with smooth en-doplasmic reticulum (SER) in the apical cytoplasm. In the experimental group sacrificed after 20 mo, one rat had papillary adenocarcinoma and two rats showed adenomatosis in the peripheral portion of the lung, but none in the upper respiratory tract.

Biological half time of deposited nickel oxide aerosol in rat lung by inhalation.

Abstract: Wistar male rats were exposed to nickel oxide (NiO) aerosols (mass median aerodynamic diameter, 1.2 and 4.0 μm). The average exposure concentration was controlled from a low level of 0.6 mg/m3 to a high level of 70 mg/m3 and total exposure time was 140 h. Some rats were sacrificed just after the exposure, whereas others were exposed for 1 mo and kept for 12 and 20 mo clearance periods before sacrifice.

Selenium retention and inhibition of cell growth in mouse mammary epithelial cell lines in vitro.

Abstract: The steady state levels of growth inhibitory doses of inorganic selenium were examined in five different mammary epithelial cell lines: MOD, COMMA-D, COMMA-F, COMMA-T, and YN-4. The retention of selenium was monitored using a radioactive isotope,75Se. Growth inhibition correlated with high levels of selenium in the cell. Generally, the retention of intracellular selenium was not dependent upon cell density, cell number, net growth rate, or tumorigenicity of the mammary cell lines. One cell line, COMMA-D, exhibited an unique response wherein the amount of selenium retained was low and the growth inhibitory effects of selenium were negligible when the cells were exposed to selenium at low density. However, at high cell densities, the COMMA-D cells responded like the other four cell lines. The growth inhibitory effect of selenium was reversible; upon removal of selenium from the medium, cells start synthesizing DNA within 24h. The retention of selenium was influenced by constituents in the growth medium. In particular, cysteine, but not methionine, purines, or pyrimidines altered selenium retention and counteracted the growth inhibitory effects of selenium. These results indicated that the mammary cell lines, particulary COMMA-D and MOD are good model systems to examine the uptake, retention, localization, and function of inorganic selenium under conditions where it acts as a growth inhibitory agent.

Effects of dietary lead, cadmium, mercury, and selenium on fatty acid composition of blood serum and erythrocyte membranes from chicks

Abstract: A series of experiments was conducted to study the effects of dietary and injected lead (as Pb acetate-3H2O) and of dietary Cd, Hg, and Se on fatty acid composition of serum lipids of chicks as measured by gas-liquid chromatography. The effect of dietary Pb on fatty acid composition of erythrocyte membranes was measured also. Dietary Pb (1000 ppm) increased the serum concentration of arachidonic acid (20:4, first no. = no. of carbon atoms:second no. = no. of double bonds) and decreased the concentration of linoleic acid (18:2) and the ratio 18:2/20:4. Intraperitoneal injection of Pb (52 mg/100 g body weight) did not alter serum fatty acid composition by 4 h post-injection. The separate effects of 2000 ppm Pb, 60 ppm Cd, 500 ppm Hg, and 10 ppm Se added to the diet on serum fatty acids were measured in a single experiment. In comparison to controls, Pb and Cd lowered serum concentration of 18:2. Only Pb raised serum 20:4. Pb lowered the ratio 18:2/20:4, whereas Cd and Hg raised the ratio and Se was without effect. Dietary Pb (2000 ppm) raised the concentration of 20:4 and lowered the ratio 18:2/20:4 in erythrocyte membranes. The different effects of injected and dietary Pb on the serum 18:2/20:4 ratio suggest that Pb alters 20:4 synthesis from 18:2 rather than mobilization of 20:4 from tissues. The Pb-induced increase of lipid peroxida-tion in erythrocytes observed by other workers may be a reflection of increased 20:4 level in erythrocyte membranes.

Interactions between selenium and tin, selenium and lead, and their effects on alad activity in blood.

Abstract: Interactions of tin and selenium, as well as of lead and selenium, were investigated in male ICR mice. The toxic effects of selenium on mortality and body weight loss were reduced by simultaneous injection with tin or lead; among mice that were injected ip with selenium at 100 μmol/kg, the 24 h survival rate was 20%, whereas among mice that were administered selenium and tin or selenium and lead at the dose of 100 μmol/kg each, the rates were 100% and 90%, respectively. As for δ-aminolevulinic acid dehydratase (ALAD, EC 4.2.1.24), lead and tin were strong inhibitors, which is well known; selenium showed no effect. When more than an equimolar dose of sodium selenite was injected ip simultaneously with stannous chloride, the ALAD activity was completely retained. On the other hand, in the simultaneous injection with sodium selenite and lead acetate of differing ratios (Se/Pb), 1, 2.5, 5, and 7.5, selenium did not exhibit an obvious protective effect against the inhibition of ALAD activity caused by lead. It is suggested that selenium protects essential thiol groups in ALAD that are otherwise blocked by invading tin; in contrast, selenium, under similar conditions, does not prevent interactions of lead with enzyme thiol groups.

A study of inter- and intrasubject variability in seven-day weighed dietary intakes with particular emphasis on trace elements.

Abstract: In this study of inter- and intrasubject variance of trace element (TE) dietary intake data, 14 female university students recorded weighed, self-selected food intakes for seven consecutive days, starting on a randomly selected day of the week. Daily intakes of energy, dietary fiber, macronutrients, 7 vitamins, and Fe, Zn, Cu, Mn, and Se were calculated using food composition tables and literature values. Analysis of variance showed a significant weekend effect for energy and TE intakes that was reduced when data were expressed on the basis of nutrient densities. No day of the working week or training effect was noted for energy or any nutrient. The ratios of the inter- to intrasubject coefficient of variation for all the nutrients were surprisingly constant. However, the overall coefficients of variation—Fe, 36.5%; Zn, 45.7%; Cu, 43.7%; Mn, 58.2%, and Se, 52.7%—were markedly lower than for vitamin A (109.0%), Vitamin D (117.1%), and linoleic acid (82.2%), but slightly higher than those for energy (27.2%) and carbohydrate (30.1%). The widespread distribution of TE in the diets results in comparable reliability for dietary studies of TE and macronutrients. The 95% confidence intervals for mean individual TE intakes ranged from 25% (Zn) to 40% (Se). These relatively large uncertainties make it essential that any assessment of the significance of correlations between dietary TE intakes and biochemical indices takes into account the intra-individual variation associated with both variables.

Pulmonary deposition and clearance of a nickel oxide aerosol by inhalation.

Abstract: Wistar male rats were exposed to nickel oxide (NiO) aerosols (mass median aerodynamic diameter, 1.2 μm). The average exposure concentration was controlled from low level (0.6 mg/m3) to high level (8.0 mg/m3) and total exposure time ranged from 140 to 216 h. Some rats were sacrificed just after the exposure, whereas others were exposed for 1 mo and kept for a 1-yr clearance period before sacrifice.

Iron, zinc, and copper content in the tissues of the rat during pregnancy

Abstract: The levels of iron, zinc, and copper in the tissues of the pregnant rat, on d 12, 19, and 21 after impregnation have been determined and compared with controls. Iron levels decreased considerably in late pregnancy as a result of increased fetal requirements, thus diminishing iron stores in rat tissues, but maintaining the circulating plasma levels. Copper levels increased slightly at midpregnancy, but returned to control levels at the end of gestation. Zinc stores also increased slightly during early pregnancy, yet were decreased at the end of pregnancy, but to a lesser extent than those of iron. The data are explained on the basis of equilibrium between assimilation and fetal needs for copper, a slightly higher demand for zinc with altered equilibrium, and a much altered equilibrium for iron that provokes a dwindling of iron maternal reserves that is not compensated by dietary iron.

Influence of zinc depletion and zinc status on serum growth hormone levels in rats

Abstract: In a preceding trial, the growth hormone concentrations in the serum of zinc-deficient rats were greatly reduced compared to thead libitum- fed control animals. The same reduction, however, was also noted in the case of the pair-fed control animals with strongly diminished feed intake. Therefore, it was not possible to distinguish between the effects of zinc deficiencyper se and the effects resulting from restricted feed intake.

Serum selenium, glutathione peroxidase, lipids, and human liver microsomal enzyme activity : A double-blind controlled trial of selenium supplementation.

Abstract: This study evaluated selenium status in relation to lipid peroxidation, liver microsomal function, and serum lipids in humans. Serum selenium concentration, glutathione peroxidase (GSH-Px) activity, liver microsomal enzyme activity, assessed by plasma antipyrine clearance (AP-CL) rate, and serum lipids were determined in 23 healthy subjects in a double-blind placebo-controlled trial of selenium supplementation. The low selenium concentration (74.0±14.2 μg/L, mean±SD) is attributable to the low selenium content of the diet. Subjects with the lowest selenium levels (n=11) had reduced serum GSH-Px activity, AP-CL rate, high-density lipoprotein cholesterol (HDL-C), and total cholesterol (T-C) as compared with subjects with higher selenium concentrations (n=12). Low AP-CL rates were associated with low HDL-C: T-C ratios. Selenium supplementation, 96 μg/d for 2 wk, increased serum selenium, GSH-Px activity, and the HDL-C: T-C ratio. The results suggest that a low serum selenium level is associated with a decrease in liver microsomal enzyme activity and serum HDL-C and T-C concentrations. Selenium supplementation in subjects with low serum selenium may favorably influence relations between serum lipoproteins connected with the development of atherosclerotic vascular disease.

Zinc supplements and reproduction in grazing ewes.

Abstract: Six experiments were carried out in Western Australia to further investigate the effect of zinc supplementation on the reproductive performance of grazing Merino ewes. There was a small increase (7%,P=0.1) in the number of lambs produced by zinc-supplemented ewes in only one of the six experiments. Plasma zinc levels just prior to lambing were increased by zinc supplementation in two experiments. These results are discussed and compared to the previously published reproductive responses to zinc supplementation by grazing Merino ewes.

Serum zinc and copper in hyperlipoproteinemia.

Abstract: Starting from experimental observations demonstrating that a high ratio of zinc to copper led to hypercholesterolemia in rats, serum Zn and Cu levels were measured by atomic absorption spectrophotometry in 65 normolipemic controls and in 100 subjects with various types of hyperlipoproteinemia (HLP). Serum Zn levels did not significantly differ from control values in any type of HLP. However, hyperlipoproteinemic patients with obvious clinical atherosclerosis displayed significantly lower serum-Zn concentration than hyperlipo-proteinemic subjects without clinical symptoms. On the other hand, when compared to control subjects, serum Cu levels were not found to be decreased, but rather increased, in hyperlipoproteinemic patients with or without atherosclerosis. As a result, the Zn∶Cu ratio appeared to be lower than normal in hyperlipoproteinemic patients with cardiovascular disease. It is conceivable that changes of these trace elements should be rather connected to vessel injury and associated disease than to HLP which, at least in humans, is not accompanied by a high Zn∶Cu ratio.

Biliary copper excretion in the chicken.

Abstract: A series of experiments were performed to examine the nature of biliary copper excretion in the chicken. Gallbladder and hepatic bile were collected from chickens fed diets that altered copper excretion. Bile was fractionated using gel filtration chromatography and SDS-PAGE. Chicks fed the control diet excreted copper that was bound primarily to a protein aggregate of greater than 600,000 daltons and secondarily, to a 7400 dalton compound. When biliary copper levels were elevated, the distribution of copper associated with the binding compounds was changed. Both the proportion and the absolute amounts of copper in the secondary pool increased dramatically when biliary copper increased. The excretion patterns observed in the control animals are believed to represent the steady-state distribution of copper in bile. A similar distribution was observed with rat bile that was obtained under steady-state conditions. These distribution patterns differ from those reported by other investigators who examined biliary copper excretion in the rat using different experimental conditions.

Arsenic concentration in the urine of patients with Blackfoot disease and Bowen’s disease

Abstract: Extensive epidemiological study implicates that high arsenic content in artesian well water is the causal factor responsible for Blackfoot disease. We determine the arsenic concentration in urine samples of patients with Blackfoot and Bowen’s diseases and examine whether there exists any discrepancy of urinary arsenic concentrations among patients and the normal population. The analyses were made by hydride atomic absorption spectrophotometry (AAS) and the analytical reliability of the method was checked with a standard urine sample (ORTHO Bi-Level Urine Metal Control). The results show that the mean urinary arsenic concentration in 100 healthy adults is 63.4±29.7 μg/L, and those means for 23 and 11 patients with Blackfoot disease and Bowen’s disease are 75.7±39.1 μg/L (P vs controls >0.05) and 201±58 μg/L (P vs controls <0.001), respectively. From the analytical results obtained, we cannot conclude that urinary arsenic is associated with Blackfoot disease, as was disclosed from the epidemiological studies. However, urinary arsenic concentrations are possibly very closely associated with Bowen’s disease.

Multiple sclerosis : A multielement survey.

Abstract: Levels of 35 elements have been measured in whole blood and ultrasonically washed scalp hair from multiple sclerosis patients and matched control subjects from Oxford, England. Among the significant differences found, the low levels of vanadium and the high levels of barium in the patients were most marked and consistent. Although the etiological significance of the observations is unknown, the low hair-vanadium levels are in qualitative agreement with a previous Canadian report. Hair- and blood-lead levels in the patients and the controls were virtually identical.

Synthesis, cytostatic, and antitumor properties of new rh(i) thiazole complexes.

Abstract: Six new organometallic derivatives of Rh(I), belonging to the general structure [Rh(CO)2(L)(Cl)], were synthesized and characterized by chemical analysis and IR determinations. The following ligands (L) were employed: 2-aminothiazole, thiazole, 2-amino-6-bromobenzothiazole, 5-chloro-2-methylthiobenzothiazole, 2-bromo-thiazole, and 2-isopropylthiazole. These new complexes were assayed in vitro with KB cells and in vivo with mice bearing established P388 and L1210 leukemias. Assays against S180 and Ehrlich ascitic tumors were also performed. Two complexes displayed antitumor activity against ascitic tumors.

The effect of pH and lysosomal extract on rat liver metallothionein (Cd-thionein).

Abstract: Was studied in vitro. The109Cd-labeled protein was isolated by gel filtration and incubated with a lysosomal extract from the same source. No degradation was seen when the pH of the incubation medium was 5 or higher, whereas the degradation of Cd-thionein was completed in 2 h at a pH of 4.5. Dissociation of Cd2+ from thionein, which takes place to a fair extent at a pH below 5, appears necessary before the enzymatic breakdown of the thionein moiety can take place.

Substitution of selenocysteine for cysteine in a reticulocyte lysate protein synthesis system

Abstract: Selenocysteine occurs in the peptide backbone of several selenoenzymes. The mechanism, of selenocysteine incorporation has not been well characterized. The incorporation of selenocysteine into protein in a rabbit reticulocyte lysate (RRL) was studied at high levels of selenocysteine. [(75)Se]Selenocysteine incorporation was inhibited by cycloheximide and by nuclease treatment. Random RNA copolymers were tested for protein synthesis activity in the messenger RNA-dependent RRL system. Of the active polymers, poly CIU and GU most strongly stimulated the incorporation of selenocysteine. In a series of four polymers with different ratios of U to G, incorporation of selenocysteine and cysteine increased with increasing percentages of U, suggesting that selenocysteine and cysteine responded to the same codon, presumably UGU. Of the 20 protein amino acids, only cysteine and cystine competed with selenocysteine incorporation. Selenocysteine was charged to cysteine-accepting tRNA in RRL. These results show that at supraphysiological concentrations selenocysteine can substitute for cysteine in RRL protein synthesis. Misincorporation of selenocysteine could be important when animal tissues contain high levels of selenium.

Stimulation of proliferation ofTetrahymena pyriformis by trace rare earths.

Abstract: Using two Chinese strains ofTetrahymena pyriformis, S1 and BJ4, as the biological models, the effects of lighter rare earths (lanthanum, cerium, praseodymium, neodymium, samarium, and europium), representatives of heavier rare earths (yttrium and thulium), and mixed rare earths were studied. The stimulation of population growth ofTetrahymena in peptone-glucose media containing trace amounts of these elements have been observed. The mechanisms for the beneficial effects of rare earth elements in low concentrations remains to be discovered.

The effects of manganese deficiency during prenatal and postnatal development on mitochondrial structure and function in the rat.

Abstract: The influence of manganese deficiency on liver trace element concentration, MnSOD activity, and mitochondrial structure and function during postnatal development was determined in rats. In both normal and manganese-deficient animals, liver manganese concentration increased with time, but in deficient rats liver manganese was lower than in controls at all ages measured. At 9 mo of age, liver manganese concentration in the deficient rats was only 20% that of controls. The developmental pattern observed for MnSOD paralleled that of liver manganese concentration in normal and deficient rats; it was lower than in controls on days 20 and 60. However, at 9 mo of age, MnSOD levels were similar in the two groups. Although there were no differences at 9 mo of age in MnSOD activity between the groups, manganese-deficient rats showed mitochondrial abnormalities in liver. Despite mitochondrial abnormalities, however, oxygen uptake and P/O ratios were normal. We suggest that the mitochondrial damage apparent at 9 mo of age is, at least in part, the result of lower than normal MnSOD activity occurring earlier. The functional significance of the abnormalities remains to be established.

Hepatic zinc, copper, and iron in the developing turkey embryo and newly hatched poult.

Abstract: The ontogeny of hepatic tissue growth and trace metal deposition was examined in the developing turkey embryo and newly hatched poult. Hepatic concentrations of zinc and iron in the embryo declined by about twofold between day 16 of incubation and hatching. Hepatic copper concentration increased approximately fourfold by day 23 of incubation and then declined rapidly through hatching. During the post-hatching period, hepatic zinc concentration increased twofold by day 10, whereas a small increase in hepatic iron concentration occurred just prior to hatching and continued through the third day post-hatching. A significant positive correlation existed between hepatic zinc and iron concentrations in the developing embryo. The concentrations of both these metals were inversely correlated with hepatic copper concentration during the same time. Total hepatic zinc and iron content increased throughout the entire time studied, whereas total copper content increased up to hatching and then declined during the first week post-hatching. The most rapid phase of hepatic metal accretion differed for each metal, with zinc being rapidly accumulated during the post-hatching period, copper during the last half of incubation and iron at about the time of hatching and the first few days post-hatching. Each of these metals demonstrated a specific relationship to hepatic tissue growth that changed between the embryonic and neonatal periods of development.