High levels of transition metals in dinoflagellate chromosomes

X-ray microanalysis of fixed, sectioned chromosomes of the dinoflagellates Glenodinium foliaceum, Prorocentrum micans and Amphidinium carterae has revealed high levels of iron, nickel, copper and zinc. We report high levels of these transition metals in association with chromosomes in intact eukaryote cells.     

Effects of dosage and cadmium pretreatment on the binding of cadmium in rat bile

Summary The effects of dosage and of cadmium pretreatment on the binding of cadmium in rat bile were studied. With increasing dose a higher cumulative biliary excretion of Cd was observed and a higher percentage of the Cd was excreted in a low-molecular-weight form. On the other hand, after cadmium pretreatment, a decrease in the cumulative biliary excretion of cadmium was observed but a greater percentage of that excreted into the bile was bound to high molecular weight compounds.     

Effects of dosage and cadmium pretreatment on the binding of cadmium in rat bile.

The effects of dosage and of cadmium pretreatment on the binding of cadmium in rat bile were studied. With increasing dose a higher cumulative biliary excretion of Cd was observed and a higher percentage of the Cd was excreted in a low-molecular-weight form. On the other hand, after cadmium pretreatment, a decrease in the cumulative biliary excretion of cadmium was observed but a greater percentage of that excreted into the bile was bound to high molecular weight compounds.     

The effect of ascorbic acid on cadmium accumulation in guinea pig tissues

Accumulation of cadmium in organs of guinea pigs after subchronic oral cadmium treatment (1 mg Cd/animal/24 h) was in the following order: kidneys > liver > heart > testes > brain. The preventive effects of high doses of ascorbic acid (AA) against cadmium deposition were more pronounced in the testes, heart and brain, and in the kidney only after short-term cadmium treatment. Ascorbic acid had no protective effect on cadmium accumulation in the liver.     

The effect of ascorbic acid on cadmium accumulation in guinea pig tissues.

Accumulation of cadmium in organs of guinea pigs after subchronic oral cadmium treatment (1 mg Cd/animal/24 h) was in the following order: kidneys > liver > heart > testes > brain. The preventive effects of high doses of ascorbic acid (AA) against cadmium deposition were more pronounced in the testes, heart and brain, and in the kidney only after short-term cadmium treatment. Ascorbic acid had no protective effect on cadmium accumulation in the liver.     

Human health effects of exposure to cadmium

Summary The health effects of human exposure to cadmium are discussed with emphases on intake, absorption, body burden, and excretion; osteomalacia in Japan; hypertension; and proteinuria, emphysema, osteomalacia, and cancer in workers. Elevated blood pressure has not been observed as a result of excessive exposures to cadmium in Japan or the workplace. Renal tubular dysfunction and consequent proteinuria is generally accepted as the main effect following long-term, low-level exposure to cadmium. Studies of workers show that proteinuria may develop after the first year of exposure or many years after the last exposure. Proteinuria and deterioration of renal function may continue even after cessation of exposure. The immediate health significance of low-level proteinuria is still under debate. However, there is evidence that long-term renal tubular dysfunction may lead to abnormalities of calcium metabolism and osteomalacia. The few autopsy and crosssectional studies of workers do not permit conclusions to be drawn regarding the relationship between cadmium exposure and emphysema. Retrospective and historical-prospective studies are needed to settle this important question. No conclusive evidence has been published regarding cadmium-induced cancer in humans. However, there is sufficient evidence to regard cadmium as a suspect renal and prostate carcinogen. Because of equivocal results and the absence of dose-response relationships, the studies reviewed should be used with caution in making regulatory decisions and low-dose risk assessments.     

Biological indicators of cadmium exposure and toxicity

The increasing environmental and occupational exposure of populations to cadmium creates the need for biological indicators of cadmium exposure and toxicity. The advantages and disadvantages of monitoring blood cadmium, urinary, fecal, hair, and tissue cadmium, serum creatinine, beta 2-microglobulin, alpha 1-antitrypsin and other proteins, and urinary amino acids, enzymes, total proteins, glucose, beta 2-microglobulin, retinol-binding protein, lysozyme, and metallothionein are discussed. It is concluded that urinary cadmium, metallothionein and beta 2-microglobulin may be used together to assess cadmium exposure and toxicity.     

Release of pre-absorbed cadmium from cultured cells by the addition of copper ion

Summary The biological interaction between cadmium and copper has been studied. Cadmium uptake of KB cells was specifically inhibited by the addition of copper ions to the culture medium. Cadmium which had already been taken up by the cells was released following the addition of copper ions.The authors are grateful to Dr. M. Ishizawa for his helpful discussion.     

Evidence for reopening of the cranial neural tube in mouse embryos treated with cadmium chloride

Summary Use of the whole-embryo culture technique resulted in experiemtal evidence that the pathogenesis of exencephaly in mouse embryos after cadmium chloride treatment results from reopening of the cranial neural tube.     

Evidence for reopening of the cranial neural tube in mouse embryos treated with cadmium chloride

Use of the whole-embryo culture technique resulted in experimental evidence that the pathogenesis of exencephaly in mouse embryos after cadmium chloride treatment results from reopening of the cranial neural tube.     

Inhibition of cadmium teratogenesis by a mercaptoacrylic acid (MFA)

The teratogenic effect of cadmium can be diminished by a number of mechanisms including zinc and pretreatment with cadmium and mercury. In this study, the oral administration of alpha-mercapto-beta-(2-furyl)-acrylic acid (MFA) protects against cadmium-induced malformations and embryonic death. This protection is probably mediated by the chelation of the cadmium ion rather than metallothionein (MT) synthesis.     

Biological indicators of cadmium exposure and toxicity

Summary The increasing environmental and occupational exposure of populations to cadmium creates the need for biological indicators of cadmium exposure and toxicity. The advantages and disadvantages of monitoring blood cadmium, urinary, fecal, hair, and tissue cadmium, serum creatinine, ₂-microglobulin, ₁-antitrypsin and other proteins, and urinary amino acids, enzymes, total proteins, glucose ₂-microglobulin, retinol-binding protein, lysozyme, and metallothionein are discussed. It is concluded that urinary cadmium, metallothionein and ₂-microglobulin may be used together to assess cadmium, exposure and toxicity.     

Chronic cadmium intake results in dose-related excretion of metallothionein in urine

Urinary excretion of metallothionein was measured by radioimmunoassay in rats given drinking water containing 5 or 50 mg cadmium/l for up to 2 years. The metallothionein levels corresponded to the concentration of cadmium in the drinking water and increased linearly over the course of the study. These results demonstrate that urinary metallothionein is a sensitive biological indicator of oral cadmium exposure.     

Teratogenic effects of cadmium on Bufo arenarum during gastrulation

Developing Bufo arenarum embryos were treated during gastrulation with cadmium chloride in concentrations ranging from 6x10(-7) to 1.5x10(-5)M Cd++ at 20 and 30 degrees C. Initial failures at gastrulation result mainly in axial incurvations, microcephaly, hydropsy and abnormal tail formation. The higher temperature has a dual effect: at high concentrations of Cd early malformations are significantly increased; whereas, at low concentrations the higher temperature prevents alterations.     

Inhibition of cadmium teratogenesis by a mercaptoacrylic acid (MFA)

Summary The teratogenic effect of cadmium can be diminished by a number of mechanisms including zinc and pretreatment with cadmium and mercury. In this study, the oral administration of -mercapto--(2-furyl)-acrylic acid (MFA) protects against cadmium-induced malformations and embryonic death. This protection is probably mediated by the chelation of the cadmium ion rather than metallothioneim (MT) synthesis.This project has been financed in part with Federal funds from the U.S. Environmental Protection Agency under grant number R811078. The contents do not necessarily reflect the views and policies of the Environmental Protection Agency nor does mention of trade names or commercial products constitute endorsement of recommendation for use.We thank Dr W. Layton for the statistical analyses of the data and G. McClain for the synthesis of MFA.     

Chelate treatment in acute cadmium poisoning

Summary Treatment of cadmium-poisoned rats with mixed ligand chelates does not decrease the lethality of cadmium more than treatment with one chelate alone.     

Teratogenic interactions between cadmium and radiation in mice

Summary Mouse embryos were exposed to various doses of cadmium and/or X-rays on day 8 of gestation. The combined treatment exerted an antagonistic effect regarding the teratogenic action of the two agents.     

Extraordinary levels of cadmium and zinc in a marine sponge,Tedania charcoti Topsent: inorganic chemical defense agents

The Antarctic marine spongeTedania charcoti has been shown to contain extraordinarily high natural concentrations of cadmium and zinc, which have in turn been correlated to the ability of the crude ethanol extract to modulate protein phosphorylation in chicken forebrain and to inhibit the growth of several test bacteria.     

Concentration and method of cadmium fixation by a marine Vibrio]

In many organisms, intracellular fixation of cadmium involves specific proteins, the metallothioneins. A similar phenomenon was demonstrated in a marine bacterium belonging to the genus Vibrio. The accumulation of the metal is a function of its concentration in the medium. The uptake is also increased by cysteine, which decreases the toxicity of the metal.     

Toxic effect of cadmium nitrate on the liver ofChanna punctatus

Summary Exposure of a fresh water fish,Channa punctatus, in a medium containing as low as 0.01 ppm of cadmium nitrate, resulted in the necrosis of hepatic cells. A temporary recovery of these cells was however observed when the animals were exposed to lower concentrations.The investigations were carried out in the Department of Zoology, Gujarat University, Ahmedabad. One of us (Punita Shah) wishes to thank UGC for the award of JRF during present investigations.