Neutralizing effect of zinc oxide on dehydroabietic acid-induced toxicity on human polymorphonuclear leukocytes

The cytotoxic effect of dehydroabietic acid (DHAA), a resin acid found in rosin, was studied on human polymorphonuclear leukocytes using leakage of 51Cr from prelabeled cells, supravital staining, and transmission electron microscopy. DHAA caused a strong dose-related release of 51Cr, a high uptake of trypan blue, and total cell necrosis, as seen in transmission electron microscopy. Albumin slightly reduced the toxic effects, whereas the addition of zinc in various forms strongly inhibited these toxic effects of DHAA in the concentration range of 10-500 micrograms/mL. In the presence of albumin, zinc oxide as a suspension inhibited the damage of the cell membranes more than a filtrate of zinc oxide, indicating a subsequent slow release of zinc from the zinc oxide.     

Zinc deficiency and the formation of white structures in immature embryo cultures of wheat (Triticum aestivum L.)

The effect of microelements on the induction of embryogenic callus from epiblast and scutellum of wheat (Triticum aestivum L.) embryos was studied by the sequential omission of each of the microelements from Murashige & Skoog medium. Omission of iron caused a marked decrease in yield and poor shoot formation from embryogenic callus. The yield of embryogenic callus on medium without added manganese was also reduced. Omission of boron, copper-cobalt, iodine, and molybdenum had little effect on the induction of embryogenic epiblast callus. By contrast there was a marked increase in the formation of white structures on the medium without any microelements or, specifically without addition of zinc. Since the formation of typical embryoids of wheat is associated with the formation of white structures, our result highlights the importance of certain microelements on somatic embryogenesis of wheat.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - MS medium Murashige & Skoog medium     

Solution-state structure by NMR of zinc-substituted rubredoxin from the marine hyperthermophilic archaebacterium Pyrococcus furiosus.

The three-dimensional solution-state structure is reported for the zinc-substituted form of rubredoxin (Rd) from the marine hyperthermophilic archaebacterium Pyrococcus furiosus, an organism that grows optimally at 100 degrees C. Structures were generated with DSPACE by a hybrid distance geometry (DG)-based simulated annealing (SA) approach that employed 403 nuclear Overhauser effect (NOE)-derived interproton distance restraints, including 67 interresidue, 124 sequential (i-j = 1), 75 medium-range (i-j = 2-5), and 137 long-range (i-j > 5) restraints. All lower interproton distance bounds were set at the sum of the van Der Waals radii (1.8 A), and upper bounds of 2.7 A, 3.3 A, and 5.0 A were employed to represent qualitatively observed strong, medium, and weak NOE cross peak intensities, respectively. Twenty-three backbone-backbone, six backbone-sulfur (Cys), two backbone-side chain, and two side chain-side chain hydrogen bond restraints were include for structure refinement, yielding a total of 436 nonbonded restraints, which averages to > 16 restraints per residue. A total of 10 structures generated from random atom positions and 30 structures generated by molecular replacement using the backbone coordinates of Clostridium pasteurianum Rd converged to a common conformation, with the average penalty (= sum of the square of the distance bounds violations; +/- standard deviation) of 0.024 +/- 0.003 A2 and a maximum total penalty of 0.035 A2. Superposition of the backbone atoms (C, C alpha, N) of residues A1-L51 for all 40 structures afforded an average pairwise root mean square (rms) deviation value (+/- SD) of 0.42 +/- 0.07 A. Superposition of all heavy atoms for residues A1-L51, including those of structurally undefined external side chains, afforded an average pairwise rms deviation of 0.72 +/- 0.08 A. Qualitative comparison of back-calculated and experimental two-dimensional NOESY spectra indicate that the DG/SA structures are consistent with the experimental spectra. The global folding of P. furiosus Zn(Rd) is remarkably similar to the folding observed by X-ray crystallography for native Rd from the mesophilic organism C. pasteurianum, with the average rms deviation value for backbone atoms of residues A1-L51 of P. furiosus Zn(Rd) superposed with respect to residues K2-V52 of C. pasteurianum Rd of 0.77 +/- 0.06 A. The conformations of aromatic residues that compose the hydrophobic cores of the two proteins are also similar. However, P. furiosus Rd contains several unique structural elements, including at least four additional hydrogen bonds and three potential electrostatic interactions.(ABSTRACT TRUNCATED AT 400 WORDS)     

Temporal fluctuations of silver,copper and zinc in the bivalve Macoma balthica at five stations in South San Francisco Bay

Concentrations of Cu, Ag and Zn were measured in the soft tissues of the estuarine bivalve Macoma balthica in South San Francisco Bay at near-monthly intervals for periods of two to three years at four stations, and eight years at a metal-enriched station. The amplitude and frequency of fluctuations differed among stations and among metals. Fluctuations were greatest at stations with the greatest metal enrichment and with the least dilution and flushing of wastes. A consistent seasonal pattern of fluctuation in Cu and Ag concentrations was evident in M. balthica at the metal-enriched station. These seasonal changes in tissue metal concentrations appeared to be affected by metal inputs, hydrologic processes that may affect both metal concentrations and bioavailability, and seasonal changes in the weight of the bivalve. The contributions of each of these interacting factors could not be determined quantitatively. At the metal-enriched station significant variation in the amplitude of seasonal fluctuations was also evident from year to year. Interpretation of metal concentrations in bivalves from estuaries will require careful consideration of the processes which affect metal dynamics in these complex environments.     

The phytate and mineral content of some cereals,cereal products,legumes, legume products,snack bars,and nuts available in New Zealand

Analyses for phytate by an indirect precipitation method and for the minerals calcium (Ca), zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn) by atomic absorption spectrophotometry were carried out on 100 foods available in New Zealand. Foods with 1% phytate (dry weight basis) included untoasted muesli, rolled oats, wheat germ, wheat bran, soybean, and some soy products. Most breads contained between 0.35 and 0.60% phytate; legumes on average had 0.62% phytate, as did snack bars. There was a wide variation in Ca and Zn contents: There was a tenfold variation in Ca content among the legume products, whereas there was a seventyfold variation in Zn content among the cereals. The phytate: Zn molar ratio, which is presumed to indicate the biovailability of Zn, was above 20∶1 for two-thirds of the cereals and almost all of the snack bars; it was above 15∶1 for one-third of the breads, almost all of the legumes, and half of the legume products. These high phytate: Zn molar ratios, as well as some Ca: phytate molar ratios above 6∶1, indicate that there might be a reduced biovailability of Zn in many of the foods analyzed in this study.     

Cardiac copper,magnesium, and zinc in recent and old myocardial infarction

X-ray fluorescence spectrometry and atomic absorption spectrometry were used in a quantitative study of zinc, copper, and magnesium in 71 postmortal human hearts. Samples were obtained from individuals who had demonstrated no previous clinical or subsequent pathological findings of myocardial infarction and from victims of a recent or an old infarction. A significant difference (p<0.001) in the elemental levels was observed between the noninfarct and the recent infarct groups. The noninfarct group had higher cardiac levels of all three elements. However, the difference in elemental concentrations between the noninfarct and the old-infarct groups was not significant. Cardiac levels of zinc (p<0.001) and copper (p<0.01) were significantly greater in the old-infarct group than in the recent-infarct group. Magnesium levels were higher in the recent-and-old-infarct group than in the recent infarct group (p<0.01). It is possible that the elements are redistributed during myocardial infarction, and that uptake of these elements (from the serum pool) by the heart may be important in maintaining myocardial integrity and function.     

Effects of CuDIPS and tween 80 on SJL/J tumorigenesis

Plasma copper and zinc levels were measured in SJL/J mice, an inbred strain characterized by a high, spontaneous incidence of reticulum cell sarcoma (RCS). The changes with age in mean concentrations of these metals were consistent with a physiological response that is required for remission of neoplasia. Treatment of SJL/J mice with a copper complex, Cu(II)(3,4-diisopropylsalicylate)₂ (Cu 3,5-DIPS), dissolved in a 10% Tween 80-saline solution revealed a decrease in survival and decline in the incidence of RCS at 52 wk of age. The toxic effects of Cu 3,5-DIPS therapy appeared to be related to the intraperitoneal route of administration and to extracellular deposition of collagen. The inhibitory effect on tumor development was not related to Cu 3,5-DIPS. Rather, Tween 80 was found to be the factor of importance.     

Metabolism of parenterally administered zinc and cadmium in livers of newborn rats

The interaction of injected zinc and cadmium with metallothionein was investigated in newborn rats. Tissues of 5-day-old rats were removed 24 h after a single injection (Sc) of saline or zinc (20 mg/kg, body wt.) or cadmium (1 mg/kg, body wt.) with 2.5 μCi of ⁶⁵Zn or ¹⁰⁹Cd or 5 μCi of [³⁵S]cysteine. Injection of zinc resulted in a 75% increase in the hepatic zinc concentration with a concomitant elevation of metallothionein (P < 0.001), zinc in metallothionein increased by 45% (P < 0.05); [³⁵S]cysteine incorporation indicated the induced synthesis of metallothionein. Injection of cadmium did not alter either metallothionein or zinc levels in liver, but cadmium in cytosol was preferentially bound to metallothionein. Neither treatment altered hepatic copper metabolism and copper in metallothionein, nor renal zinc and metallothionein levels. These data indicate that zinc injection can elevate hepatic zinc levels and induce metallothionein synthesis in newborn rats despite high basal levels; cadmium injection does not induce metallothionein synthesis, though cadmium is avidly sequestered by pre-existing metallothionein. The differences in the induction of metallothionein by these divalent cations can be explained by the differences in their binding affinities for thiol groups in intracellular metallothionein.     

Effect of lead on blood protoporphyrin levels of a group of ring teal ducks (Callonetta leucophrys)

This research determined the relationships between blood lead level and zinc protoporphyrin (ZnPROTO), protoporphyrin IX (PROTO), and free erythrocyte protoporphyrin (FEP) levels in a group of 18 ring teal ducks. Blood samples were drawn from two groups of ring teal ducks as part of the routine health maintenance program of the New York Zoological Park. One group of six teals had been exposed to what is believed to be lead-contaminated dust, while the second group of twelve teals was unexposed. Blood samples were analyzed for lead by flameless atomic absorption and for protoporphyrins by fluorescence. Blood lead level and log blood lead level had positive correlations with each of the protoporphyrins: the logarithmic correlations were better than the nonlogarithmic correlations, and PROTO correlated better than ZnPROTO. With one exception, PROTO levels were higher than ZnPROTO levels. The results suggest that PROTO, FEP, or ZnPROTO could serve as a biological indicator of lead poisoning in ring teal ducks.