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A plasmid, R773, which confers resistance to arsenic compounds, is transmissible between strains of Escherichia coli. It is a member of compatibility group F(1).
In this study, we observed the in vivo acute immunotoxicity of a trimethyl arsenic compound, arsenobetaine (AsBe), which is present in large quantities in various marine animals that are daily ingested as seafood in many countries. The synthetic pure AsBe was orally administered to CDF(1) mice at a dose of 1.625 g/kg mouse weight once a day on days -6, -4, -2 and 0 (four times, total 6.5 g/kg mouse weight), and its effect on the immune organs and immune effector cells were assessed until day 8. Orally administered AsBe was temporally distributed to the immune organs, such as the spleen and thymus, but was not very toxic both quantitatively and qualitatively on these immune organs and immune effector cells, splenocytes, thymocytes, Peyer's patch lymphocytes and peritoneal macrophages. This finding suggests that the ingestion of AsBe contained in marine animals is relatively safe to the health of people who often consume marine animals in their daily diet.
A new liquid chromatographic separation method was developed for the speciation of the four main arsenic compounds present in water. Arsenite (As(III)), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and arsenate (As(V)) were separated on a recently introduced stationary phase: porous graphitic carbon (PGC). The separation was first obtained under formic acid gradient conditions, but an adsorption phenomenon of As(V) on PGC was observed. To overcome this problem, As(V) was backflushed, and an efficient separation of the four solutes was achieved within 10 min. Extremely low detection limits (ranging from 10 to 70 ng x L(-1)) were obtained by coupling LC with an ICPMS. The method was successfully applied to different spiked mineral waters and a naturally arsenic-containing freshwater.
Due to a number of cases of acute arsine poisonings in one of zinc metallurgic plants, the environmental concentrations of arsenic compounds were determined. In the technological process of zinc metallurgy, the highest arsine concentrations can occur: a) during zinc refining in the furnace, where, because of the full automatization process, the presence of workers is not necessary, b) during the refining furnace repair--because of the melting loss wetting. Levels of arsenic concentrations, just as cadmium and zinc concentrations, according to the valid hygienic standards, are very low at the shaft furnace and the agglomerating plant. The urinary arsenic concentrations in workers has not exceeded 100 micrograms/l and these results also testify to a small exposure. However, it is necessary to take into account the high lead concentrations at some work-posts, both due to the multiple exceeding of the hygienic standard, and the simultaneous occurrence of lead and arsenic, which create a potential possibility of forming more toxic compounds, e.g. lead arsenide. In view of the carcinogenic exposure, it is important to take into account the possibility of interaction between arsenic and polycyclic aromatic hydrocarbones which occur during coke dry degassing.
The major water-soluble arsenic compound was isolated from the muscle of shortnose dogfish Squalus brevirostris and of starspotted shark Mustelus manazo, both of which are demersal sharks. The isolated compound was identified to be arsenobetaine by its chromatographic and spectrometric analyses.
The trypanocidal activity of an arsenical compound (RM 110; mel Cy; Cymelarsan) was tested in susceptible and drug-resistant stocks of T.b. brucei and T.b. evansi in vitro and in vivo. The trypanosome stocks showed different levels of susceptibility in an in vitro test, their IC50 values ranging from 3-26.9 nM. Mel Cy was 2.2-2.7 times more active against T.b. brucei stocks when compared to another arsenical (mel W; Trimelarsan). The logarithmically transformed IC50 values for both drugs obtained with T.b. brucei stocks correlated significantly. Significant correlations were also found between the log IC50 values of each of the two drugs and diminazene aceturate. In mice, the least susceptible stock was cured with a single i.p. dose of mel Cy which was about 16 times higher than that needed to cure a susceptible stock.
Bioaccumulation and biotransformation of arsenic (As) compounds in freshwater Tilapia mossambica was investigated. The direct accumulation of As by T mossambica was proportional to the concentration of arsenicals in water. Small amounts of accumulated As were transformed to methylated As, including trimethylarsenic (TMA) species. Accumulation and transformation of As(III) by T. mossambica via freshwater food chain results in the transformation of As(III) to As(V) with little biomethylation of accumulated As. Approximately 90% of accumulated As was depurated to water.
Experiments to grow Tetraselmis chuii (a marine alga) and Daphnia magna in the presence of inorganic arsenate are described. The algae incorporate arsenic rather efficiently and form a lipid-soluble organic arsenic compound. T. chuii has been successfully mass cultured in a medium containing 10 ppm arsenic as arsenate. Daphnia magna was cultured in a medium containing 74As-labeled H3AsO4 and 1 ppm Na2HAsO4 expressed as arsenic. The arsenic metabolites were extracted with a chloroform-methanol solution and isolated by using column and thin-layer chromatography. TLC analysis of the metabolites revealed the presence of a 74As-containing product which migrated with phosphatidylethanolamine. This product was hydrolyzed with the phospholipases A, C, and D. The experimental results are not inconsistent with the presence of an arsenocholine moiety in the lipids. Arsenocholine, arsenobetaine, and acetylarsenocholine have been synthesized and will serve as reference substances in the chromatography experiments. The preparation of arsenocholine-containing lipids is in progress.
A method using high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS) has been developed to determine inorganic arsenic (arsenite, arsenate) along with organic arsenic compounds (monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, trimethylarsine oxide, tetramethylarsonium ion and several arsenosugars) in fish, mussel, oyster and marine algae samples. The species were extracted by means of a methanol/water mixture and a dispersion unit in 2 min, with extraction efficiencies ranging from 83 to 107% in the different organisms. Up to 17 different species were determined within 15 min on an anion-exchange column, using a nitric acid gradient and an ion-pairing reagent. As all species are shown in one chromatogram, a clear overview of arsenic distribution patterns in different marine organisms is given. Arsenobetaine is the major compound in marine animals whereas arsenosugars and arsenate are dominant in marine algae. The method was validated with CRM DORM-2 (dogfish muscle). Concentrations were within the certified limits and low detection limits of 8 ng g(-1) (arsenite) to 50 ng g(-1) (arsenate) were obtained.
The toxicity of arsenic III, arsenic V, sodium dimethyl arsenate, and disodium methyl arsenate to stoneflies, snails, amphipods, and trout, and the bioaccumulation of these compounds were studied during a 28-day flow-through test. Daphnia magna were exposed for 21 days in static tests to determine life-cycle effects. All animals were exposed to concentrations of approximately 100 and 1000 microgram/L (as arsenic) of each of the compounds. Arsenic III, the most toxic compound, caused a significant reduction in the survival of amphipods at 1000 microgram As/L after seven days. None of the compounds significantly affected the survival of other test species after 28 days or reduced young production in Daphnia after 14 days of exposure. The concentration of accumulated arsenic in stoneflies, snails, and Daphnia was as much as 131, 99, and 219 times greater than the water concentration, whereas amphipods and rainbow trout contained arsenic residues similar to the controls. Residues in stoneflies, snails, and Daphnia exposed to 1000 microgram As/L were higher than those in animals exposed to 100 microgram As/L, but appeared to reach a steady state after 14 days. Total arsenic accumulation was greatest in organisms exposed to inorganic arsenic, particularly at 100 microgram/L.
This paper describes a routine, robust, and reproducible liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) speciation method for five arsenic compounds [arsenobetaine (AB), arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)] in urine. Concentrations of these arsenic species in urine samples are reported in two sets of non-occupationally exposed controls with one set having consumed fish within 24 h (n = 31) and the other not having consumed fish for 48 h (n = 34). Arsenic species in urine samples from workers in both the timber treatment industry (n = 49) and semiconductor industry (n = 46) are also reported. The arsenic content in all of the samples was also determined using hydride-generation coupled with ICP-MS. The results show that urine samples from people not occupationally exposed to arsenic contain low levels of DMA, MMA, and AB and that only urine from smokers contained any inorganic arsenic. Consumption of seafood was seen to significantly increase the levels of AB and DMA in the unexposed persons. Urine samples from the semiconductor workers exhibited significantly higher levels of arsenite, arsenate, and DMA than the unexposed samples. The urine samples from timber treatment workers exhibited significantly higher levels of four arsenic species (not AB) than those observed in both the control groups and the semi-conductor workers.
A capillary zone electrophoresis (CZE) method with indirect UV detection was developed to simultaneously separate inorganic and organic arsenic compounds including arsenite (iAsIII), arsenate (iAsV), monomethylarsonate and dimethylarsenic acid (DMAV). 2,6-Pyridinedicarboxylic acid (PDC) and n-hexadecyltrimethylammonium hydroxide (CTAOH) were selected to compose a background electrolyte (BGE), where PDC was used as chromophore and CTAOH functioned as electroosmotic flow (EOF) modifier to reduce/eliminate EOF. The choice of detection wavelength, the optimization of BGE pH, and effects of applied electric field strength and temperature on separation were further investigated. The limits of detection for the targeted analytes were between 0.19 and 0.23 ppm as molecule. Good linearity of more than three orders of magnitude was obtained. Repeatability of migration times and peaks areas were 0.8-1.7 and 3.4-6.9% R.S.D.; whereas reproducibility were 1.2-2.2 and 3.6-7.1% R.S.D., respectively. The established CZE method was then applied to analyze the alkali extracts of realgar (As2S2) and orpiment (As2S3). The main components in both alkali extracts were identified to be iAsIII and iAsV.
A capillary electrophoresis-inductively coupled plasma-mass spectrometric (CE-ICP-MS) method for the speciation of six arsenic compounds, namely arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid, dimethylarsinic acid, arsenobetaine and arsenocholine is described. The separation has been achieved on a 70 cm length x 75 microm ID fused-silica capillary. The electrophoretic buffer used was 15 mM Tris (pH 9.0) containing 15 mM sodium dodecyl sulfate (SDS), while the applied voltage was set at +22 kV. The arsenic species in biological tissues were extracted into 80% v/v methanol-water mixture, put in a closed centrifuge tube and kept in a water bath, using microwaves at 80 degrees C for 3 min. The extraction efficiencies of individual arsenic species added to the sample at 0.5 microg As/g level were between 96% and 107%, except for As(III), for which it was 89% and 77% for oyster and fish samples, respectively. The detection limits of the species studied were in the range 0.3-0.5 ng As/mL. The procedure has been applied for the speciation analysis of two reference materials, namely dogfish muscle tissue (NRCC DORM-2) and oyster tissue (NIST SRM 1566a), and two real-world samples.
Several chronic bioassays have been conducted in multiple strains of mice in which various concentrations of arsenate or arsenite were administered in the drinking water without a tumorigenic effect. However, one study (Ng et al., 1999) reported a significant increase in tumor incidence in C57Bl/6J mice exposed to arsenic in their drinking water throughout their lifetime, with no tumors reported in controls. A physiologically based pharmacokinetic model for arsenic in the mouse has previously been developed (Gentry et al., 2004) to investigate potential differences in tissue dosimetry of arsenic species across various strains of mice. Initial results indicated no significant differences in blood, liver, or urine dosimetry in B6C3F1 and C57Bl/6 mice for acute or subchronic exposure. The current work was conducted to compare model-predicted estimates of tissue dosimetry to additional kinetic information from the (C57Bl/6 xCBA)F1 and TgAc mouse. The results from the current modeling indicate that the pharmacokinetic parameters derived based on information in the B6C3F1 mouse adequately describe the measured concentrations in the blood/plasma, liver, and urine of both the (C57Bl/6 x CBA)F1 and TgAc mouse, providing further support that the differences in response observed in the chronic bioassays are not related to strain-specific differences in pharmacokinetics. One significant finding was that no increases in skin or lung concentrations of arsenic species in the (C57Bl/6 x CBA)F1 strain were observed following administration of low concentrations (0.2 or 2 mg/U of arsenate in the drinking water, even though differences in response in the skin were reported. These data suggest that pharmacodynamic changes may be observed following exposure to arsenic compounds without an observable change in tissue dosimetry. These results provided further indirect support for the existence of inducible arsenic efflux in these tissues.
The methylation of inorganic arsenic to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) have been generally considered to be the major pathway for inorganic arsenic biotransformation and detoxification. Yet, when arsenate/arsenite is injected into the Callithrix jacchus (marmoset) monkey or chimpanzee, monomethylarsonic acid and dimethylarsinic acid are not found in the urine. With the development of a rapid assay for the methyltransferases of arsenic metabolism, we have investigated the methyltransferases of the marmoset monkey liver. We have found that the marmoset, a New World animal, is deficient in liver arsenite and monomethylarsonic acid methyltransferase activities. However, the rhesus monkey, an Old World animal, has ample amounts of such methyltransferase activities. The tamarin, another New World species, is also deficient in these methyltransferases. Polymorphism and deficiency of these methyltransferases may have allowed high levels of arsenite to be maintained in the blood and liver of the marmoset and tamarin. Such high levels of arsenite may have been selective for survival of the species. The rhesus liver methyltransferases for arsenite and MMA have been purified and found to have some properties different from those of the previously reported purified rabbit liver activities. The rhesus and rabbit liver arsenite and MMA methyltransferases are devoid of catechol O-methyltransferase activity.
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The response of human and bovine peripheral blood lymphocytes to PHA stimulation was measured in the presence of low concentrations of sodium arsenite and sodium arsenate. In bovine lymphocytes, 41% augmentation of the response occurred at 10(-6) M arsenite with a return to the normal response at 2.5 X 10(-6) M. Complete inhibition of mitogenesis occurred at 6 X 10(-6) M. In the presence of sodium arsenate, similar results were obtained but at the higher concentrations of 2 X 10(-5) (for 57% augmentation), 5.2 X 10(-5), and 1.9 X 10(-4) M, respectively. The possible significance of these findings in view of the known relationship between chronic arsenicalism and human skin cancer is discussed. It is suggested that arsenic compounds may, by potentiating mitogenesis, increase the possibility of errors in DNA replication, some of which could be potentially carcinogenic. Additionally, interference with the immune response could enable potentially cancerous cells to escape immune surveillance.