Formulation Comprising Arsenic Trioxide and Dimercaprol Enhances Radiosensitivity of Pancreatic Cancer Xenografts.

OBJECTIVE: To investigate the efficacy of a formula comprising arsenic trioxide and dimercaprol (BAL-ATO) as a radiosensitizing agent in model mice with pancreatic cancer xenografts. METHODS: Female BALB/c nude mice bearing SW1990 human pancreatic cancer xenografts were divided into four treatment arms, including control, radiotherapy (RT), BAL-ATO, and RT + BAL-ATO groups. Survival and tumor volume were analyzed. We also assessed apoptosis in tumor samples by live imaging and detected hypoxia by confocal laser microscope observation. We further investigated the mechanisms of BAL-ATO action in RT by detecting affected proteins by western blot and immunohistochemistry assays. RESULTS: Median survival was significantly longer in the RT + BAL-ATO group (64.5 days) compared with the control (49.5 days), RT (39 days), and BAL-ATO (48 days) groups (P < 0.001). RT + BAL-ATO inhibited the growth of tumors in mice by 73% compared with the control group, which was significantly higher than the rate of inhibition following RT alone (59%) (P < 0.01). Further analysis showed an improved microenvironment in terms of hypoxia in tumors treated with BAL-ATO alone or RT + BAL-ATO. Expression of signaling molecules associated with pancreatic cancer stem cells, including CD24, CD44, ALDH1A1, Gli-1, and Nestin, was detected in tumors treated with BAL-ATO alone or in combination with RT. CONCLUSION: These data suggest that BAL-ATO function as a radiosensitizer in mice with pancreatic cancer xenografts, via mechanisms involving hypoxia reduction and inhibition of signaling pathways associated with pancreatic cancer stem cells. BAL-ATO may thus be a promising radiosensitizing agent in patients with pancreatic cancer.

Dimercaprol is an acrolein scavenger that mitigates acrolein-mediated PC-12 cells toxicity and reduces acrolein in rat following spinal cord injury.

Acrolein is one of the most toxic byproducts of lipid peroxidation, and it has been shown to be associated with multiple pathological processes in trauma and diseases, including spinal cord injury, multiple sclerosis, and Alzheimer's disease. Therefore, suppressing acrolein using acrolein scavengers has been suggested as a novel strategy of neuroprotection. In an effort to identify effective acrolein scavengers, we have confirmed that dimercaprol, which possesses thiol functional groups, could bind and trap acrolein. We demonstrated the reaction between acrolein and dimercaprol in an abiotic condition by nuclear magnetic resonance spectroscopy. Specifically, dimercaprol is able to bind to both the carbon double bond and aldehyde group of acrolein. Its acrolein scavenging capability was further demonstrated by in vitro results that showed that dimercaprol could significantly protect PC-12 cells from acrolein-mediated cell death in a dose-dependent manner. Furthermore, dimercaprol, when applied systemically through intraperitoneal injection, could significantly reduce acrolein contents in spinal cord tissue following a spinal cord contusion injury in rats, a condition known to have elevated acrolein concentration. Taken together, dimercaprol may be an effective acrolein scavenger and a viable candidate for acrolein detoxification.

One step derivatization with British Anti-Lewsite in combination with gas chromatography coupled to triple-quadrupole tandem mass spectrometry for the fast and selective analysis of inorganic arsenic in rice.

We developed a new fast and selective analytical method for the determination of inorganic arsenic (iAs) in rice by a gas chromatography - tandem mass spectrometry (GC-MS/MS) in combination with one step derivatization of inorganic arsenic (iAs) with British Anti-Lewsite (BAL). Two step derivatization of iAs with BAL has been previously performed for the GC-MS analysis. In this paper, the quantitative one step derivatization condition was successfully established. The GC-MS/MS was carried out with a short nonpolar capillary column (0.25 mm × 10 m) under the conditions of fast oven temperature ramp rate (4 °C/s) and high linear velocity (108.8 cm/s) of the carrier gas. The established GC-MS/MS method showed an excellent linearity (r(2) > 0.999) in a tested range (0.2-100.0 µg L(-1)), ultra-low limit of detection (LOD, 0.08 pg), and high precision and accuracy. The GC-MS/MS technique showed far greater selectivity (22.5 fold higher signal to noise ratio in rice sample) on iAs than GC-MS method. The gas chromatographic running time was only 2.5 min with the iAs retention time of 1.98 min. The established method was successfully applied to quantify the iAs contents in polished rice. The mean iAs content in the Korean polished rice (n = 27) was 66.1 µg kg(-1) with the range of 37.5-125.0 µg kg(-1). This represents the first report on the GC-tandem mass spectrometry in combination with the one step derivatization with BAL for the iAs speciation in rice. This GC-MS/MS method would be a simple, useful and reliable measure for the iAs analysis in rice in the laboratories in which the expensive and element specific HPLC-ICP-MS is not available.

Cytotoxic Effect of Lipophilic Bismuth Dimercaptopropanol Nanoparticles on Epithelial Cells.

Bismuth nanoparticles have many interesting properties to be applied in biomedical and medicinal sectors, however their safety in humans have not been comprehensively investigated. The objective of this research was to determine the cytotoxic effect of bismuth dimercaptopropanol nanoparticles (BisBAL NPs) on epithelial cells. The nanoparticles are composed of 18.7 nm crystallites on average and have a rhombohedral structure, agglomerating into chains-like or clusters of small nanoparticles. Based on MTT viability assay and fluorescence microscopy, cytotoxicity was not observed on monkey kidney cells after growing with 5 µM of BisBAL NPs for 24 h. Employing same techniques, identical results were obtained with human epithelial cells (HeLa), showing a not strain-dependent phenomenon. The absence of toxic effects on epithelial cells growing with BisBAL NPs was corroborated with long-time experiments (24-72 hrs.), showing no difference in comparison with growing control (cells without nanoparticles). Further, genotoxicity assays, comet assay and fluorescent microscopy and electrophoresis in bromide-stained agarose gel revealed no damage to genomic DNA of MA104 cells after 24 h. of exposition to BisBAL NPs. Finally, the effect of bismuth nanoparticles on protein synthesis was studied in cells growing with BisBAL NPs for 24 h. SDS-PAGE assays showed no difference between treated and untreated cells, suggesting that BisBAL NPs did not interfere with protein synthesis. Hence BisBAL NPs do not appear to exert cytotoxic effects suggesting their biological compatibility with epithelial cells.

Modeling the chelation of As(III) in lewisite by dithiols using density functional theory and solvent-assisted proton exchange.

Dithiols such as British anti-lewisite (BAL, rac-2,3-dimercaptopropanol) are an important class of antidotes for the blister agent lewisite (trans-2-chlorovinyldichloroarsine) and, more generally, are chelating agents for arsenic and other toxic metals. The reaction of the vicinal thiols of BAL with lewisite through the chelation of the As(III) center has been modeled using density functional theory (DFT) and solvent-assisted proton exchange (SAPE), a microsolvation method that uses a network of water molecules to mimic the role of bulk solvent in models of aqueous phase chemical reactions. The small activation barriers for the stepwise SN2-type nucleophilic attack of BAL on lewisite (0.7-4.9kcal/mol) are consistent with the favorable leaving group properties of the chloride and the affinity of As(III) for soft sulfur nucleophiles. Small, but insignificant, differences in activation barriers were found for the initial attack of the primary versus secondary thiol of BAL and the R vs S enantiomer. An examination of the relative stability of various dithiol-lewisite complexes shows that ethanedithiols like BAL form the most favorable chelation complexes because the angles formed in five-membered ring are most consistent with the hybridization of As(III). More obtuse S-As-S angles are required for larger chelate rings, but internal As⋯N or As⋯O interactions can enhance the stability of moderate-sized rings. The low barriers for lewisite detoxification by BAL and the greater stability of the chelation complexes of small dithiols are consistent with the rapid reversal of toxicity demonstrated in previously reported animal models.

A computational study of detoxification of lewisite warfare agents by British anti-lewisite: catalytic effects of water and ammonia on reaction mechanism and kinetics.

trans-2-Chlorovinyldichloroarsine (lewisite, L agent, Lew-I) acts as a blistering agents. British anti-lewisite (BAL, 2,3-dimercaptopropanol) has long been used as an L-agent antidote. The main reaction channels for the detoxification proceed via breaking of As-Cl bonds and formation of As-S bonds, producing stable, nontoxic ring product [(2-methyl-1,3,2-dithiarsolan-4-yl)methanol]. M06-2X/GENECP calculations have been carried out to establish the enhanced rate of detoxification mechanism in the presence of NH3 and H2O catalysts in both gas and solvent phases, which has been modeled by use of the polarized continuum model (PCM). In addition, natural bond orbital (NBO) and atoms in molecules (AIM) analysis have been performed to characterize the intermolecular hydrogen bonding in the transition states. Transition-state theory (TST) calculation establishes that the rates of NH3-catalyzed (2.88 × 10(-11) s(-1)) and H2O-catalyzed (2.42 × 10(-11) s(-1)) reactions are reasonably faster than the uncatalyzed detoxification (5.44 × 10(-13) s(-1)). The results obtained by these techniques give new insight into the mechanism of the detoxification process, identification and thermodynamic characterization of the relevant stationary species, the proposal of alternative paths on modeled potential energy surfaces for uncatalyzed reaction, and the rationalization of the mechanistic role played by catalysts and solvents.

Superhydrophobic fiber mats by electrodeposition of fluorinated poly(3,4-ethyleneoxythiathiophene).

The control of surface morphology and wettability is crucial in the development of superhydrophobic surfaces, which implies new strategy and molecular design. In this Article, we report the synthesis, characterization, and electrochemical properties of original 3,4-ethyleneoxythiathiophenes (EOTT) as platform molecules and its derivatives bearing a semifluorinated chain of various length (F-octyl, F-hexyl, F-butyl, and F-ethyl). We report the influence of the fluorinated chain length as well as the presence of sulfur atoms in the monomer on the surface construction and nonwetting properties of the corresponding electrodeposited polymer films. Surprisingly, these films exhibit the possibility to obtain extremely long polymer fibers with a possible control of their length by a careful choice in the monomer structure. We show that the presence of sulfur atoms in the monomer structure seems to be necessary to modulate the formation of extremely long polymer fibers by aggregation of smaller polymer fibrils. In this Article, the formation of superhydrophobic material (contact angle above 150°) for four, six, and eight fluoromethylene units but also highly hydrophobic surfaces (contact angle above 125°) from extremely short chains (two fluoromethylene units) is also demonstrated.

Quantification of arsenic compounds using derivatization, solvent extraction and liquid chromatography electrospray ionization tandem mass spectrometry.

The difficulty in detecting inorganic arsenic compounds using conventional settings of mass chromatography has led to the use of derivatizing agents to aid in their detection. A recent study indicated that 2,3-dimercaptopropanol (BAL) could be used to derivatize arsenic compounds to make them detectable by LC coupled to UV detector. A speciation analysis method was then developed for arsenic compounds after derivatization using the LC-MS/MS with the aim to improve the sensitivity and specificity. The arsenic compounds were derivatized with BAL before solvent extraction was carried out. The resultant extract was analyzed using the LC-MS/MS. However, our finding showed that BAL, being a thiol, reduced the pentavalent arsenic compounds, As(V) to a trivalent state, As(III). The arsenic metabolites, monomethyl arsonate (MMA) and dimethyl arsenic acid (DMA) could also be reduced by BAL to As(V)- and As(III)-BAL adducts. Despite this, the assay could be used to quantify the total arsenic concentration as a summation of all these adducts, when speciation of individual arsenic species is not required. The developed LC-MS/MS assay was subsequently applied to detect arsenic compounds in rat urine samples after oral administration of arsenic trioxide.

Study on the interaction between 2-mercaptoethanol, dimercaprol and CdSe quantum dots.

The interactions between 2-mercaptoethanol, dimercaprol and CdSe quantum dots (QDs) in organic media have been investigated by spectral methods. The results showed that the fluorescence (FL) emission of CdSe QDs gradually decreased, with a slight red-shift, after adding thiols to CdSe QDs solutions. With the increase of the concentrations of thiols, the resonance light scattering (RLS) signal of CdSe QDs had been strongly enhanced in the wavelength range 300-500 nm, which was confirmed by the formation of larger CdSe QDs particles. The effect of thiols on the FL emission of CdSe QDs could be described by a Stern-Volmer-type equation with the concentration ranges 1.0 x 10(-6)-7.5 x 10(-4) mol/L for 2-mercaptoethanol and 1.0 x 10(-7)-2.5 x 10(-5) mol/L for dimercaprol. The possible mechanism of the interaction was proposed according to the results of UV-vis absorption and micro-Raman spectroscopy. The results indicated that FL quenching was mainly attributable to the exchange of the QDs surface molecules.

Syntheses of RNAs with up to 100 nucleotides containing site-specific 2'-methylseleno labels for use in X-ray crystallography.

The derivatization of nucleic acids with selenium is a new and highly promising approach to facilitate their three-dimensional structure determination by X-ray crystallography. Here, we report a comprehensive study on the chemical and enzymatic syntheses of RNAs containing 2'-methylseleno (2'-Se-methyl) nucleoside labels. Our approach includes the first synthesis of an appropriate purine nucleoside phosphoramidite building block. Most importantly, a substantially changed RNA solid-phase synthesis cycle, comprising treatment with threo-1,4-dimercapto-2,3-butanediol (DTT) after the oxidation step, is required for a reliable strand elongation. This novel operation allows for the chemical syntheses of multiple Se-labeled RNAs in sizes that can typically be achieved only for nonmodified RNAs. In combination with enzymatic ligation, biologically important RNA targets become accessible for crystallography. Exemplarily, this has been demonstrated for the Diels-Alder ribozyme and the add adenine riboswitch sequences. We point out that the approach documented here has been the chemical basis for the very recent structure determination of the Diels-Alder ribozyme which represents the first novel RNA fold that has been solved via its Se-derivatives.

Switching of the electronic communication between two {Ru(trpy)(bpy)} (trpy = 2,2':6',2' '-terpyridine and bpy = 2,2'-bipyridine) centers by protonation on the bridging dimercaptothiadiazolato ligand.

A stable Ru(II)/Ru(III) mixed-valence state was observed in acetonitrile for the ruthenium binuclear complex bridged by dimercaptothiadiazolate (DeltaE(1/2) = 220 mV for Ru(2)(II,II)/Ru(2)(II,III) and Ru(2)(II,III)/Ru(2)(III,III) processes; K(com) = 5.3 x 10(3)). Upon protonation of the bridging ligand by the addition of equimolar p-toluenesulfonic acid, however, the mixed-valence state diminished (DeltaE(1/2) = 0 mV). The bridging ligand operates as a proton-induced switch of the electronic communication in the dimeric complex.

Speciation of dimethylarsinous acid and trimethylarsine oxide in urine from rats fed with dimethylarsinic acid and dimercaptopropane sulfonate.

Speciation of arsenic in urine from rats treated with dimethylarsinic acid (DMA(V)) alone or in combination with dimercaptopropane sulfonate (DMPS) were studied. Methods were developed for the determination of the methylarsenic metabolites, especially trace levels of dimethylarsinous acid (DMA(III)) and trimethylarsine oxide (TMAO), in the presence of a large excess of DMA(V). Success was achieved by using improved ion-exchange chromatographic separation combined with hydride generation atomic fluorescence detection. Micromolar concentrations of DMA(III) were detected in urine of rats fed with a diet supplemented with either 100 microg/g of DMA(V) or a mixture of 100 microg/g of DMA(V) and 5600 microg/g of DMPS. No significant difference in the DMA(III) concentration was observed between the two groups; however, there was a significant difference in TMAO concentrations. Urine from rats fed with the diet supplemented with DMA(V) alone contained 73 +/- 30 microM TMAO, whereas urine from rats fed with the diet supplemented with both DMA(V) and DMPS contained only 2.8 +/- 1.4 microM TMAO. Solutions containing mixtures of 100 microg/L DMA(V) or TMAO and 5600 microg/L DMPS did not show reduction of DMA(V) and TMAO. The significant decrease (p < 0.001) of the TMAO concentration in rats administered with both DMA(V) and DMPS suggests that DMPS inhibits the biomethylation of arsenic.

British anti-Lewisite (dimercaprol): an amazing history.

Emergency physicians are familiar with British anti-Lewisite (BAL) because it is a heavy metal-chelating agent that is recommended in some cases of metal poisoning, especially arsenic. Although there are more modern chelating agents, the fact that BAL is still recommended and stocked by hospital pharmacies more than 60 years after its initial synthesis is itself remarkable. During World War II, BAL minimized the risk to the Allied infantry of injury or death from Lewisite, a very potent arsenic-based chemical warfare agent. Once developed, BAL revolutionized the treatment of heavy metal poisonings, both accidental and iatrogenic (eg, toxicity from treatment of arthritis with gold salts). In 1951, BAL was used to treat Wilson's disease with striking success. Today, BAL might again become prominent should terrorists or governments use Lewisite against civilians or military forces.

S-methyl derivatives from thiol compounds by the pyrolytic reaction with trimethylsulfonium hydroxide.

Base-catalyzed transesterification of acyl lipids with methanol in the presence of trimethylsulfonium hydroxide (TMSH) is an easy and convenient method for the preparation of fatty acid methyl esters for gas chromatography (GC) analyses. Free fatty acids are converted to fatty acid methyl esters by the pyrolytic reaction with TMSH as well. We have found that lipids and other compounds containing thiol groups are also converted easily to the corresponding methyl sulfides (methyl thioethers) by the pyrolytic reaction with TMSH occurring in the injector of the gas chromatograph. For example, alkane thiols such as dodecane thiol and octadecane thiol are converted to the corresponding alkyl methyl sulfides, whereas bis(methylthio) derivatives are formed from alpha,omega-alkane dithiols, e.g., 1,8-octanedithiol, and from 2,3-dimercaptopropan-1-ol (dimercaprol). Furthermore, 3beta-mercaptocholest-5-ene (thiocholesterol) is converted to 3-methylthiocholest-5-ene by the same reaction. The S-methylation reactions which finally lead to the corresponding methylthio derivatives of lipids and other compounds with thiol groups may be of diagnostic value for the structural analysis of such compounds by GC and GC/mass spectrometry.

Spectrophotometric determination of the positional specificity of nonspecific and 1,3-specific lipases.

Using commercially available thiosubstrates, such as 2,3-dimercapto-1-propanol tributyrate, the regio-specificities of 1,3-specific and nonspecific lipases was confirmed. The spectrophotometric test is a simple, rapid, and convenient alternative method to those previously reported for the characterization of the positional specificities of new lipases.

Prebiotic polymerization: oxidative polymerization of 2,3-dimercapto-1-propanol on the surface of iron(III) hydroxide oxide.

The oxidation of 2,3-dimercapto-1-propanol by ferric ions on the surface of iron(III) hydroxide oxide (Fe(OH)O) yielded polydisulfide oligomers. This polymerization occurred readily at low dithiol concentration under mild aqueous conditions. Polydisulfide polymers up to the 15-mer were synthesized from 1 mM dithiol in 5 ml water reacted with iron(III) hydroxide oxide (20 mg, 160 micromoles Fe) for 3 days under anaerobic conditions at 40 degrees C and pH 4. About 91% of the dithiol was converted to short soluble oligomers and 9% to insoluble larger oligomers that were isolated with the Fe(OH)O phase. Reactions carried out at the same ratio of dithiol to Fe(OH)O but at higher dithiol concentrations gave higher yields of the larger insoluble oligomers. The relationship of these results to prebiotic polymer synthesis is discussed.

[Spontaneous course of allergic bronchopulmonary aspergillosis]. / Spontanverlauf einer allergischen bronchopulmonalen Aspergillose.

This case report illustrates the spontaneous course of allergic bronchopulmonary aspergillosis (ABPA). The x-ray images cover a time-frame of nearly 20 years. All of the main criteria of ABPA are fulfilled. Despite intermittent oral corticosteroid treatment, recurrent eosinophilic infiltrates of the lungs occurred. New strategies in diagnosis and treatment of ABPA are discussed.

Modulation of airway inflammation in cystic fibrosis. In vivo suppression of interleukin-8 levels on the respiratory epithelial surface by aerosolization of recombinant secretory leukoprotease inhibitor.

Based on the knowledge that neutrophil elastase (NE) in cystic fibrosis (CF) epithelial lining fluid (ELF) can induce human bronchial epithelial cells to express the gene for interleukin 8 (IL-8), an 8.5-kD neutrophil chemoattractant, we have evaluated CF ELF for the presence of IL-8, and investigated the ability of aerosolized recombinant secretory leukoprotease inhibitor (rSLPI) to suppress NE, and hence IL-8, levels on the respiratory epithelial surface in CF. Enzyme-linked immunoassay revealed 21.9 +/- 4.8 nM IL-8 in CF ELF compared with none in normals. Active NE was detectable in ELF of all individuals with CF and was significantly decreased (P < 0.03) after aerosolization of rSLPI. Human bronchial epithelial cells exposed to CF ELF recovered before rSLPI therapy expressed IL-8 mRNA transcripts, but ELF recovered after rSLPI therapy induced far less bronchial epithelial cell IL-8 gene expression. Consistent with this, rSLPI aerosol therapy caused a marked reduction in CF ELF IL-8 levels (P < 0.05) and neutrophil number (P < 0.02). There was also a clear association between CF ELF active NE and IL-8 levels (r = 0.94). These data suggest that rSLPI therapy not only suppresses respiratory epithelial NE levels, but also breaks a cycle of inflammation on the CF epithelial surface.

Human studies with the chelating agents, DMPS and DMSA.

Meso-2,3-dimercaptosuccinic acid (DMSA) is bound to plasma albumin in humans and appears to be excreted in the urine as the DMSA-cysteine mixed disulfide. The pharmacokinetics of DMSA have been determined after its administration to humans po. For the blood, the tmax and t1/2 were 3.0 h + 0.45 SE and 3.2 h + 0.56 SE, respectively. The Cmax was 26.2 microM + 4.7 SE. To determine whether dental amalgams influence the human body burden of mercury, we gave volunteers the sodium salt of 2,3-dimercaptopropane-1-sulfonic acid (DMPS). The diameters of dental amalgams of the subjects were determined to obtain the amalgam score. Administration of 300 mg DMPS by mouth increased the mean urinary mercury excretion of subjects over a 9 h period. There was a positive correlation between the amount of mercury excreted and the amalgam score. DMPS might be useful for increasing the urinary excretion of mercury and thus increasing the significance and reliability of this measure of mercury exposure. DMSA analogs have been designed and synthesized in attempts to increase the uptake by cell membranes of the DMSA prototype chelating agents. The i.v. administration of the monomethyl ester of DMSA, the dimethyl ester of DMSA or the zinc chelate of dimethyl DMSA increases the biliary excretion of platinum and cadmium in rats.