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The accumulation, distribution and form of vanadate ions were studied in the mussel Mytilus edulis (L) and the goldfish Carassius auratus . After exposure to increasing doses from 0.5 to 500 μg/l for 4 days, the vanadium content in the mussel increased in all tissues, especially in the byssus which reached 17 μg V/g tissue. This suggests that this tissue could be useful as a marker for vanadium present in the aquatic environment. The vanadium present in the cytosol of the gills was associated with low molecular weight components, whereas in the mantle and hepatopancreas also with high molecular weights. After exposure to 50 μg V/l, Carassius auratus accumulated 0.1% of the dose. Among tissues, the intestine showed the highest concentration, being ∼0.05% of the dose after 4 days exposure. In the cytosol of the fish intestine, vanadium was found associated with low molecular weights, representing an easily available pool to be excreted. The capability of vanadium to be present in marine and freshwater organisms in biochemical form(s) other than the inorganic ones is of particular interest in assessing the exposure of man to environmental vanadium as ingested by food.

Summary A study was performed aimed at detecting the Ba ion in waters for human consumption. Samples were taken from 89 sites of the Reggio Emilia Plains. Barium determination was performed using GFAAS with both Zeeman correction or a high intensity tungsten-halogen lamp. The analytical specificity of this procedure was verified by comparison with ICP-AES. Data obtained revealed concentrations of Ba varying from 10 to 925 μg L -1 with appreciable differences among the four hydrogeological units considered. Preliminary tests of Ba speciation have led to the hypothesis that it is present in water in its soluble form, presumably of an inorganic nature or in a compound with organic substances of low molecular weight.

A method based on Zeeman GFAAS is proposed for the determination of Co in urine samples. The biological sample is diluted 1+4 v/v with a 0.2% aqueous solution of a matrix modifier made up of Mg(NO 3 ) 2 . The behavior of the analyte during the atomization process is studied by using working solutions marked with 58 Co. The detection limit of the method was 0.28 μg L -1 with recovery percentages of the element ranging from 97.8 to 99.6%. At a 5 μg L -1 concentration level the CV of the method was 3.7% within the series and 6.4% among series. The specificity of the procedure was assessed by comparison with a NAA method.

1 The fate of a soluble form of titanium (Ti) was studied in rats injected intraperitoneally with 1 ?g of Ti per rat as [44Ti]ammonium oxalotitanate (IV).2 After 16 h the Ti concentration in all tissues tested was of the order of 0.5 ng/g wet weight. After 19 days the Ti concentration increased in most tissues, especially in spleen, femur and kidney. By this time 55 ng had been excreted both via urine and faeces and the Ti concentration in blood plasma (mainly associated with plasma proteins) was three times lower than at 16 h postinjection.3 Chromatographic separation of the day 19 liver cytosol showed the ability of biological macromolecules to incorporate Ti compounds.4 Ti-labelled 'titanic acid' and 'titanium phosphate' showed low solubility which was, however, higher in human serum than in water and sodium chloride solution. The chromatographic profiles of plasma from incubated human blood in vitro with [44Ti]titanium oxalate showed the capacity of plasma proteins to complex Ti compounds. The results indicated that the long retention of Ti in the body may be due to its ability to form biocomplexes with cellular constituents.

(1981). Poisoning by Triphenyltin Acetate. Report of Two Cases and Determination of Tin in Blood and Urine by Neutron Activation Analysis. Clinical Toxicology: Vol. 18, No. 11, pp. 1343-1353.

An assessment study of the environmental pathways of arsenic released from a coal-fired power plant (CFPP) or introduced into soil as a contaminant by phosphatic fertilizers has been carried out using a time-dependent forecasting model.The long-term predictions indicate that arsenic can be taken up by plants and that it can migrate into the groundwater system through soil layers. However, arsenic exhibits such a high degree of mobility that its retention and accumulation in biota should remain low. This fact may explain the relatively low concentrations of arsenic in environmental media as well as in groundwater systems.

Bovine milk was incubated simultaneously with 48VO2+ and 59Fe3+ ions. The lactoferrin was separated by ion exchange gel chromatography on CM Sephadex C-50 resin. Sephacryl 200 gel filtration of the lactoferrin-containing fractions, from ion exchange chromatography was carried out to dertermine the proportions of 48V and 59Fe radioactivities associated with macromolecules of the size of lactoferrin. It was found that 48V was incorporated into lactoferrin, the milk protein which contains iron. This suggests that lactoferrin may play a role in the bioavailability of vanadium during lactation, as vanadium is an essential element for the growth of some animal species. More generally, the vanadium binding properties of lactoferrin further support previous findings on the possible biochemical role of Fe-containing non hemoproteins in the metabolism of vanadium.

In vivo experiments over a period up to 21 days were performed on rats to gain information on the metabolic patterns of vanadium. Animals were intravenously injected with 10 μg of 48 V-labeled V 5+ ions/rat as ammonium metavanadate and sacrificed at different postinjection periods. Timed distributions of 48 V refer to the clearance from blood and urine, determination in whole tissues, and intracellular distribution in kidneys, liver, testicles, and spleen. Gel-filtration and dialysis experiments were performed on 48 V plasma and urine to identify the vanadium-binding components. Vanadium in the blood was mainly present in the plasma and disappeared from the bloodstream with different rates corresponding to the clearance of three plasma components. Initially only a small amount of vanadium in the plasma was associated with proteins, while after a 4-day period it was present only as a vanadium-transferrin biocomplex. The principal organs of 48 V retention were kidneys, liver, testicles, and spleen. The intracellular distribution of 48 V in these tissues indicated that the nuclei were the organelles retaining the major fraction of the cellular vanadium. The main route of 48 V excretion was through the urine, in which 48 V was mainly associated with high-molecular-weight components 3 days after the 48 V injection. v

Tissue vanadium levels were determined in rats of different age by neutron activation analysis. The vanadium concentrations in the tissues of rats 21 days old are of the order of few tens of ng/g. Significant depletions of these concentrations were observed in kidney, liver lung and spleen at 115 days postnatal period. At this time the vanadium content in all tissues analysed did not exceed 10 ng/g.

The chronic exposure of man to increasing amounts of heavy metals as a consequence of environmental pollution, requires accurate knowledge of how much the homeostatic control of trace elements can stand increased exposure to abnormal amounts of metal pollutants without alteration of the biochemical functions. This topic includes the study of the accumulation of metal pollutants in the body with the identification of metal biocomplexes under long term-low level exposure (LLE) conditions. Extremely sensitive analytical techniques are required for experimentation at the heavy metal levels which are typical of a polluted environment in order to assess the limits of physiological homeostatic controls. The possiblity of applying nuclear and radiochemical techniques, such as neutron activation analysis, multiple tracing, high resolution gamma-ray spectrometry and Cerenkov counting, coupled with biochemical techniques, such as gel filtration, ion-exchange chromatography, polyacrylamide gel electrophoresis and differential centrifugation, has been demonstrated in various typical applications in metallobiochemistry. The subject of the first part of this paper is the development and improvement of the techniques, dealing with potential metal binding components, such as metalloenzymes and nucleic acids chosen as models. The developments refer to: preparation of labelled metal pollutants with very high specific activity to label in vivo nanogram or subnanogram amounts of pollutant metals; neutron activation analysis of enzymes and nucleic acids with the aim of analyzing concentrations of many metal pollutants in the identified metal binding components of the microsamples; radiochemical methods including radiobiochemical techniques for multielement tracer experiments and for studying the interaction of heavy metas and metal binding components; development of complementary counting techniques. The in vivo applications are centered on biochemical studies on cadmium, in particular on the long term-low exposure experiment, which is under investigation at present, with the identification of both critical organs of accumulation and of the cadmium binding components. Results are given for biochemical mechanisms involving cadmium such as the stimulation of the "de novo" biosynthesis of rat liver and intestine cadmium binding proteins (CdBP) and on the systematic study of the interaction of metal pollutants and rat liver cadmium binding proteins itself. Preliminary data are also given for short term experiments dealing with the identification of cellular metal binding components for V, Se, Cd and Pb.

51Cr-labelled Cr3+ and CrO2-4 solutions were administered intratracheally to male rats in doses of 0.1 and 10 μg of Cr per rat to evidentiate metabolic differences especially in the lung and in the mechanisms of excretion. Twenty four hours after administration the highest 51 Cr amount was present in the lungs for both valency states, being in the Cr (III)-treated group, however, about two times higher. In all other tissues tested the values in the Cr (VI)-treated animals were much higher. Intracellularly, in the Cr (III)-treated group more than 40% of the total lung homogenate was found in the nuclear fraction and only 10% in the cytosol. In the Cr (VI)-treated group 25% was present in the nuclei and more than 50% in the cytosol. Gel filtration 24 h after intratracheal injection showed that in both cytosols chromium was eluted in three peaks including a low-molecular-weight component. Quantitatively, however, the ratios between the 51Cr associated with the three peaks were significantly different between the Cr (III)- and the Cr (VI)-treated animals. This suggests that binding of chromium to low-molecular-weight components should be involved in the passage of this element from the lung to the other tissues. Excretion studies for 7 days showed that after this time the Cr (III)-treated animals excreted about 4% of the dose via urine and more than 36% via faeces, whereas in the Cr (VI)-treated rats the 51Cr was eliminated nearly equally between urine and faeces.

Lead ions can interact with calf intestine alkaline phosphatase. Experiments using 203Pb-labeled Pb2+ ions showed that Pb2+ ions bind the native protein in a molar ratio of Pb/protein of 1:5 with moderate inhibition of its biochemical activity. The 4 g-atoms of Zn per mol present in the native enzyme may be removed by dialysis against EDTA. The inactive apoenzyme is capable of incorporating Pb2+ ions in a Pb/protein molar ratio of 2:1, giving a lead-protein complex still enzymatically active also when genetic material, such as nucleotides or DNA, has been used a a substrate. The reconstituted lead-protein is capable of binding Zn2+ ions without any release of the Pb2+ ions and with an increase in the catalytic activity of only 10-15%. The absence of Zn in the inactive apoenzyme as well as in the reconstituted lead-protein, the incorporation of Pb2+ ions in stoichiometric amounts in the apoenzyme, and the weak influence of the Zn2+ ions on the enzymatic assay of the lead-enzyme suggest that lead ions partially reactivate the calf intestine alkaline phosphatase apoenzyme.

The study of possible relationships between iron and vanadium metabolism (E. Sabbioni and E. Marafante, Proc. XIth Int. Conf. Biochem., 13-5-R122, Toronto, Canada) was extended to the vanadium in the biochemical mechanisms which involve the exchange of iron between transferrin and ferritin. The transfer of vanadium between transferrin and ferritin was investigated using 48V radiotracer and gel filtration technique. 48V labeled human transferrin and horse spleen ferritin, 48V plasma from rats injected with 48VO2+, unlabelled rat liver cytosol, and plasma were used as sources of the two proteins for their incubation under different conditions. The results show that the equilibrium: V - transferrin in equilibrium V - ferritin occurs in vitro at physiological pH under the conditions of this experiment. No transfer of vanadium between the two proteins, however, occurs when they are incubated simply in a buffer at pH = 7.4. The maximum transfer was observed when transferrin and ferritin were mixed in their natural environments such as plasma and liver cytosol. This suggests that the exchange of the vanadium between the two proteins is affected by biochemical factors which are present in the body. A brief evaluation of the significance on the very low amounts of the element exchanged between the two proteins is also presented.

The transport of vanadium across placenta and milk rats was studied by iv injection of low doses of 48V-labeled pentavanadate (0.1 micrograms V/rat) to pregnant and nursing rats. Significant concentrations of vanadium were found in the liver, intestine, and kidneys of the fetuses, showing that vanadium is capable to pass the placental barrier and, thus, being metabolized in the fetuses. Two days after injection of 0.1 micrograms V/rat as 48V-labeled vanadate to nursing rats, 34 ng V/g milk were found, decreasing to 4 ng V/g at the d 12 after dosing. The corresponding suckling rats showed a significant absorption of vanadium taken up by the milk, as suggested by the presence in their intestine, where 48V is easily absorbed in form of low molecular weight components. Vanadium in milk may be transported in the form of a biocomplex with lactoferrin, since at 12 d after injection, the 48V in the rat milk was mainly found in fractions corresponding to proteins. In weanling rats, 7 d postlactation and 18 d after administration of vanadium to the mother, only very small amounts of 48V were still present in the organs. Excretion studies on weanling rats for 7 d showed that vanadium is rapidly released mainly via feces when earlier taken up by the milk of iv injected mothers and having the same elimination pattern as the milk, which lost about 80% of its vanadium concentration after 12 d.

The enzymatic hydrolỳsis of end-phosphate DNA by calf intestine alkaline phosphatase is inhibited by iridium chlorocomplexes. The inhibitory effect is strongly influenced by the chemical form of iridium. While hexachloroiridate (IV) and hexachloroiridite (III) strongly inhibit the enzymatic activity of calf intestine alkaline phosphatase no inhibitory effect was observed when these chlorocomplexes were previously irradiated by light and transformed to their photochemical reaction products. Evidence is presented which suggests that the noncompetitive and irreversible inhibitory effect was due to an effective interaction of iridium with the protein without release of its metal constituent at a very low concentration of enzyme. The protective effects of various chemicals on the inhibitory action was also briefly investigated.

A case of rare-earth (RE) pneumoconiosis is described and discussed. A man working in a lithographic laboratory as a photoengraver, and exposed to the smoke of cored carbon arc lamps over a period of 46 years developed an interstitial pneumoconiosis. Neutron activation analysis (NAA) of eight rare-earths (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in lung and lymph node biopsies showed an abnormally high amount of these elements in comparison to the corresponding values of 11 autopsied for unexposed subjects. The estimated radiological dose due to the inhalation of natural thorium, as calculated from NAA of thorium in the biopsies, tends to exclude the effect of ionizing radiation in the pathogenesis of lung fibrosis. Effects of other potential pathogenetic agents such as coal or heavy metal dusts, other than RE, irritative agents such as nitrous and hydrofluoric vapours originated during the photoengraving process, are also discussed. The findings strongly suggest that a relationship exists between the pneumoconiosis diagnosed and the occupational exposure to rare-earth dusts calling attention to proposals for maximum permissible concentration limits of occupational exposure to RE in air.

This study describes investigations on the possible mechanisms involved in the transfer of Cr from the dialysate to the blood during peritoneal dialysis. The ability of Cr(III) compounds to penetrate across a membrane at physiological pH seems rather questionable, as it is well known that Cr(III) tends to form polymeric chains. Therefore, a systematic study was undertaken to describe the pathways involved in this transport. The characteristics during ‘in vitro’ dialysis were compared to the behaviour of Cr during acute ‘in vivo’ experiments on anesthetized rabbits. It appeared that lactate, a common substance of the dialysate, plays an extremely important role in the mobility and subsequent transfer of Cr(III) across the peritoneum.

Mutagenic and cytogenetic effects of chromium compunnds have been analyzed in different biological systems in order to explain the molecular basis of chromium carcinogenesis. It is well known that Cr (VI) compounds are able to induce genetic activity in eukaryotic and prokaryotic systems, while Cr (III) compounds gave contrasting results. In the present work the ability of K 2 Cr 2 O 7 and CrCl 3 to induce mitotic gene conversion and point reverse mutation was investigated in vitro using stationary phase cells of the D7 strain of S. cerevisiae with and without metabolic activation. To understand the role of microsomal reduction of chromium (VI) and the permeability of membranes in the determination of genetic effects, we also used log phase cells, which contain a high level of drug metabolizing enzymes and have also a greater permeability. Genetic activity of K 2 Cr 2 O 7 was observed on D7 strain of S. cerevisiae confirming the literature data, while CrCl 3 showed a weak induction of genetic effects only when the incubation was performed using TRiS-Cl instead of a phosphate buffer. A greater induction of genetic activity was obtained on yeast cells harvested the log phase. In addition we investigated the ability of chromium chloride to enter the yeast cells and to bind to DNA using the 51 Cr radiotracer.