N-(2,3-dimercaptopropyl)phthalamidic acid: protection, in vivo and in vitro, against arsenic intoxication

Cutaneous Arsenical Exposure Induces Distinct Metabolic Transcriptional Alterations of Kidney Cells

Arsenicals are deadly chemical warfare agents that primarily cause death through systemic capillary fluid leakage and hypovolemic shock. Arsenical exposure is also known to cause acute kidney injury, a condition that contributes to arsenical-associated death due to the necessity of the kidney in maintaining whole-body fluid homeostasis. Because of the global health risk that arsenicals pose, a nuanced understanding of how arsenical exposure can lead to kidney injury is needed. We used a nontargeted transcriptional approach to evaluate the effects of cutaneous exposure to phenylarsine oxide, a common arsenical, in a murine model. Here we identified an upregulation of metabolic pathways such as fatty acid oxidation, fatty acid biosynthesis, and peroxisome proliferator-activated receptor (PPAR)-α signaling in proximal tubule epithelial cell and endothelial cell clusters. We also revealed highly upregulated genes such as Zbtb16, Cyp4a14, and Pdk4, which are involved in metabolism and metabolic switching and may serve as future therapeutic targets. The ability of arsenicals to inhibit enzymes such as pyruvate dehydrogenase has been previously described in vitro. This, along with our own data, led us to conclude that arsenical-induced acute kidney injury may be due to a metabolic impairment in proximal tubule and endothelial cells and that ameliorating these metabolic effects may lead to the development of life-saving therapies. SIGNIFICANCE STATEMENT: In this study, we demonstrate that cutaneous arsenical exposure leads to a transcriptional shift enhancing fatty acid metabolism in kidney cells, indicating that metabolic alterations might mechanistically link topical arsenical exposure to acute kidney injury. Targeting metabolic pathways may generate promising novel therapeutic approaches in combating arsenical-induced acute kidney injury.

Arsenic hazards to humans, plants, and animals from gold mining

Arsenic sources to the biosphere associated with gold mining include waste soil and rocks, residual water from ore concentrations, roasting of some types of gold-containing ores to remove sulfur and sulfur oxides, and bacterially enhanced leaching. Arsenic concentrations near gold mining operations are elevated in abiotic materials and biota: maximum total arsenic concentrations measured were 560 microg/L in surface waters, 5.16 mg/L in sediment pore waters, 5.6 mg/kg DW in bird liver, 27 mg/kg DW in terrestrial grasses, 50 mg/kg DW in soils, 79 mg/kg DW in aquatic plants, 103 mg/kg DW in bird diets, 225 mg/kg DW in soft parts of bivalve molluscs, 324 mg/L in mine drainage waters, 625 mg/kg DW in aquatic insects, 7,700 mg/kg DW in sediments, and 21,000 mg/ kg DW in tailings. Single oral doses of arsenicals that were fatal to 50% of tested species ranged from 17 to 48 mg/kg BW in birds and from 2.5 to 33 mg/kg BW in mammals. Susceptible species of mammals were adversely affected at chronic doses of 1-10 mg As/kg BW or 50 mg As/kg diet. Sensitive aquatic species were damaged at water concentrations of 19-48 microg As/L, 120 mg As/kg diet, or tissue residues (in the case of freshwater fish) > 1.3 mg/kg fresh weight. Adverse effects to crops and vegetation were recorded at 3-28 mg of water-soluble As/L (equivalent to about 25-85 mg total As/kg soil) and at atmospheric concentrations > 3.9 microg As/m3. Gold miners had a number of arsenic-associated health problems, including excess mortality from cancer of the lung, stomach, and respiratory tract. Miners and schoolchildren in the vicinity of gold mining activities had elevated urine arsenic of 25.7 microg/L (range, 2.2-106.0 microg/L). Of the total population at this location, 20% showed elevated urine arsenic concentrations associated with future adverse health effects; arsenic-contaminated drinking water is the probable causative factor of elevated arsenic in their urine. Proposed arsenic criteria to protect human health and natural resources are listed and discussed. Many of these proposed criteria do not adequately protect sensitive species.

Massive arsenic poisoning--effect of hemodialysis and dimercaprol on arsenic kinetics

In massive arsenic poisoning, the use of hemodialysis and dimercaprol (BAL) therapy is still controversial. Hemodialysis is thought of value only for supportive care. BAL therapy has been criticized because of its delayed action, its own toxicity and its possible influence on arsenic clearance during hemodialysis. We studied arsenic kinetics during an acute suicidal intoxication (10 g of sodium arsenate). Treatment included gastric lavage, oral charcoal and supportive measures. Hemodialysis was performed immediately and repeated the next day. BAL therapy was prescribed only on the second day. Cardiovascular collapse, anuria and hepatic disturbance recovered in a few days and the patient could be discharged on the 15th day. Instantaneous serum arsenic hemodialysis clearance was 85 +/- 75 ml/min without previous BAL injection and 87.5 +/- 75 ml/min with a previous 250 mg BAL injection (difference not significant) indicating that BAL did not impede arsenic dialysis. The calculated total hemodialysis clearance of arsenic was higher than mean serum hemodialysis clearance indicating that erythrocyte bound arsenic is also eliminated during dialysis. We propose to consider early hemodialysis as an elimination measure in massive arsenic poisoning and to choose BAL as a chelator when dialysis is required.

New developments in therapeutic chelating agents as antidotes for metal poisoning

An examination of the studies on therapeutic chelating agents that have been carried out during the last decade reveals that extensive efforts have been made to develop compounds superior to those previously available for the treatment of acute and chronic intoxication by many metals. These metals include primarily iron, plutonium, cadmium, lead, and arsenic, but also many other elements for which acute and chronic intoxication is less common. These studies have revealed the importance of several additional factors of importance in the design of such compounds and have led to many new compounds of considerable clinical promise. An additional development has been the introduction of previously developed chelating agents for use with certain metals on a broader scale.

The mobilization of intracellular cadmium by alkoxyethyl esters of meso-2,3-dimercaptosuccinic acid

The cadmium mobilizing properties of two newly synthesized esters of meso-2,3-dimercaptosuccinic acid in mice have been examined. They are: di(2'-methoxyethyl) meso-2,3-dimercaptosuccinate ([-CH(SH)COOCH2CH2OR]2, R = CH3; MEDMS), and di(2'-ethoxyethyl) meso-2,3-dimercaptosuccinate ([-CH(SH)COOCH2CH2OR]2, R = CH2CH3; EEDMS), conveniently prepared from dimercaptosuccinate acid with 2-methoxyethanol and 2-ethoxyethanol, respectively. Mobilization studies in mice of aged in vivo cadmium deposits using five ip injections of 0.40 mmol/kg of each chelator in peanut oil clearly indicate that both compounds, MEDMS and EEDMS, are significantly superior to 2,3-dimercaptopropan-1-ol (BAL) in depleting the whole body burden of cadmium. The reductions caused by MEDMS and EEDMS were approximately 20 and 26%, respectively, whereas under similar dosage regimens BAL effected about only a 12% reduction. The esters were neither equal nor superior to BAL for the reduction of renal cadmium levels, MEDMS being the least effective. For the mobilization of hepatic cadmium deposits, both were quite promising (MEDMS, 20%; EEDMS, 34% reduction) compared to BAL (only 2% reduction). There was no accumulation of cadmium with either MEDMS or EEDMS in any of the other organs examined--spleen, testes, pancreas, and particularly the brain. These compounds enhance the fecal excretion of cadmium by a factor of 25- to 40-fold but have very little effect on the urinary excretion of this element. The present study reveals that the order of overall efficacy is EEDMS greater than MEDMS greater than BAL, considering the liver and whole body burdens of cadmium, but BAL greater than EEDMS greater than MEDMS in terms of the efficacy in reducing cadmium levels in the kidneys.

Structural influences on intracellular cadmium mobilization by dithiols

An examination of 5 dithiols, N-(2,3-dimercaptopropyl)phthalamidic acid (DMPA), benzene-1,2-dithiol (BDT), toluene-3,4-dithiol (TDT), alpha, alpha'-dimercapto-o-xylene (DOX), and 4,5-dimethyl-alpha,alpha'-dimercapto-o-xylene (DDOX), reveals that these compounds are all inferior to previously reported compounds as agents for the in vivo mobilization of cadmium from its intracellular sites, although all possess sulfhydryl groups capable of reacting with cadmium. The results demonstrate the considerable importance of those parts of the molecule which do not participate directly in the formation of chelate rings in the determination of the ultimate behavior of such compounds in vivo.

Mobilization of lead by esters of meso-2,3-dimercaptosuccinic acid

An examination was made of the relative efficacies of 2,3-dimercapto-1-propanol (BAL) and three diesters ( [CH(SH)COOR]2; DMDMS, R = CH3; DEDMS, R = C2H5; and Di-PDMS, R = CH(CH3)2] of meso-2,3-dimercaptosuccinic acid (DMSA) in mobilizing freshly injected lead from mice. These diesters, like BAL, reduced the lead levels resulting from freshly injected lead in both the soft tissues (liver, kidneys, spleen, and brain) and the bone (tibia). After treatment with the dimethyl (DMDMS), the diethyl (DEDMS), and the diisopropyl (Di-PDMS) esters the lead content of each of the organs was significantly less than that present in the untreated controls. Each of the diesters reduced lead levels in the kidneys, liver, and spleen significantly below those levels found after BAL treatment. The action of the diesters in reducing brain lead levels was comparable to that of BAL. Di-PDMS was the most effective of these compounds and was significantly superior to BAL. Each of the esters was also significantly more effective than BAL in reducing the whole body level of lead.

Efficiency of arsenic clearance from human blood in vitro and from dogs in vivo by extracorporeal complexing haemodialysis

In vitro dialysis using human blood and in vivo extracorporeal haemodialysis trials with dogs, in the presence and absence of various chelating agents, showed that haemodialysis alone facilitated efficient removal of the metal, even in the absence of any of the chelating agents. In vitro haemodialysis for 5 hr without chelating agents caused the removal of 85% of the arsenic (As) added to the blood 1 hr before the beginning of the treatment. Ten-33% of the single dose given to the dogs, were removed into the dialysate during the first treatment and 8-15% during the second. The amounts of As excreted in the urine of dogs given 0.25 mg As/kg b.wt./day for 6 days were 6.8-7.4 mg As/24 hr, while the same amounts of the metal were removed into the dialysate during haemodialysis for 5 hr. This demonstrates the advantage of employing haemodialysis over the conventional treatment for the enhanced removal of As from the body.